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annotate ext/libpng-1.2.29/libpng-1.2.29.txt @ 502:96c4922c1c24

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Added some imports to the world initialization code. I had to do this because you were not able to use the editor with the shooter demo map files without manually adding the imports to the map file. You do not have to do this now (note the TODO in the comments). I have also hard coded the camera zoom level to ensure the map editors zoom level at the time of saving the map is not used.
author prock@33b003aa-7bff-0310-803a-e67f0ece8222
date Tue, 18 May 2010 14:48:33 +0000
parents 4a0efb7baf70
children
rev   line source
0
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1 libpng.txt - A description on how to use and modify libpng
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2
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3 libpng version 1.2.29 - May 8, 2008
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4 Updated and distributed by Glenn Randers-Pehrson
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5 <glennrp at users.sourceforge.net>
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6 Copyright (c) 1998-2008 Glenn Randers-Pehrson
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7 For conditions of distribution and use, see copyright
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8 notice in png.h.
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9
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10 Based on:
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11
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12 libpng versions 0.97, January 1998, through 1.2.29 - May 8, 2008
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13 Updated and distributed by Glenn Randers-Pehrson
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14 Copyright (c) 1998-2008 Glenn Randers-Pehrson
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15
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16 libpng 1.0 beta 6 version 0.96 May 28, 1997
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17 Updated and distributed by Andreas Dilger
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18 Copyright (c) 1996, 1997 Andreas Dilger
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19
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20 libpng 1.0 beta 2 - version 0.88 January 26, 1996
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21 For conditions of distribution and use, see copyright
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22 notice in png.h. Copyright (c) 1995, 1996 Guy Eric
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23 Schalnat, Group 42, Inc.
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24
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25 Updated/rewritten per request in the libpng FAQ
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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26 Copyright (c) 1995, 1996 Frank J. T. Wojcik
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27 December 18, 1995 & January 20, 1996
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28
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29 I. Introduction
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30
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31 This file describes how to use and modify the PNG reference library
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32 (known as libpng) for your own use. There are five sections to this
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33 file: introduction, structures, reading, writing, and modification and
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34 configuration notes for various special platforms. In addition to this
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35 file, example.c is a good starting point for using the library, as
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36 it is heavily commented and should include everything most people
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37 will need. We assume that libpng is already installed; see the
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38 INSTALL file for instructions on how to install libpng.
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39
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40 For examples of libpng usage, see the files "example.c", "pngtest.c",
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41 and the files in the "contrib" directory, all of which are included in the
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42 libpng distribution.
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43
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44 Libpng was written as a companion to the PNG specification, as a way
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45 of reducing the amount of time and effort it takes to support the PNG
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46 file format in application programs.
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47
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48 The PNG specification (second edition), November 2003, is available as
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49 a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at
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50 <http://www.w3.org/TR/2003/REC-PNG-20031110/
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51 The W3C and ISO documents have identical technical content.
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52
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53 The PNG-1.2 specification is available at
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54 <http://www.libpng.org/pub/png/documents/>. It is technically equivalent
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55 to the PNG specification (second edition) but has some additional material.
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56
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57 The PNG-1.0 specification is available
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58 as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
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59 W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
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60
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61 Some additional chunks are described in the special-purpose public chunks
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62 documents at <http://www.libpng.org/pub/png/documents/>.
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63
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64 Other information
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65 about PNG, and the latest version of libpng, can be found at the PNG home
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66 page, <http://www.libpng.org/pub/png/>.
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67
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68 Most users will not have to modify the library significantly; advanced
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69 users may want to modify it more. All attempts were made to make it as
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70 complete as possible, while keeping the code easy to understand.
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71 Currently, this library only supports C. Support for other languages
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72 is being considered.
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73
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74 Libpng has been designed to handle multiple sessions at one time,
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75 to be easily modifiable, to be portable to the vast majority of
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76 machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
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77 to use. The ultimate goal of libpng is to promote the acceptance of
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78 the PNG file format in whatever way possible. While there is still
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79 work to be done (see the TODO file), libpng should cover the
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80 majority of the needs of its users.
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81
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82 Libpng uses zlib for its compression and decompression of PNG files.
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83 Further information about zlib, and the latest version of zlib, can
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84 be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
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85 The zlib compression utility is a general purpose utility that is
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86 useful for more than PNG files, and can be used without libpng.
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87 See the documentation delivered with zlib for more details.
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88 You can usually find the source files for the zlib utility wherever you
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89 find the libpng source files.
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90
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91 Libpng is thread safe, provided the threads are using different
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92 instances of the structures. Each thread should have its own
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93 png_struct and png_info instances, and thus its own image.
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94 Libpng does not protect itself against two threads using the
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95 same instance of a structure.
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96
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97 II. Structures
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98
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99 There are two main structures that are important to libpng, png_struct
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100 and png_info. The first, png_struct, is an internal structure that
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101 will not, for the most part, be used by a user except as the first
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102 variable passed to every libpng function call.
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103
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104 The png_info structure is designed to provide information about the
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105 PNG file. At one time, the fields of png_info were intended to be
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106 directly accessible to the user. However, this tended to cause problems
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107 with applications using dynamically loaded libraries, and as a result
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108 a set of interface functions for png_info (the png_get_*() and png_set_*()
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109 functions) was developed. The fields of png_info are still available for
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110 older applications, but it is suggested that applications use the new
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111 interfaces if at all possible.
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112
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113 Applications that do make direct access to the members of png_struct (except
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114 for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
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115 and applications that make direct access to the members of png_info must
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116 be recompiled if they were compiled or loaded with libpng version 1.0.6,
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117 in which the members were in a different order. In version 1.0.7, the
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118 members of the png_info structure reverted to the old order, as they were
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119 in versions 0.97c through 1.0.5. Starting with version 2.0.0, both
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120 structures are going to be hidden, and the contents of the structures will
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121 only be accessible through the png_get/png_set functions.
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122
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123 The png.h header file is an invaluable reference for programming with libpng.
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124 And while I'm on the topic, make sure you include the libpng header file:
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125
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126 #include <png.h>
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127
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128 III. Reading
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129
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130 We'll now walk you through the possible functions to call when reading
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131 in a PNG file sequentially, briefly explaining the syntax and purpose
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132 of each one. See example.c and png.h for more detail. While
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133 progressive reading is covered in the next section, you will still
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134 need some of the functions discussed in this section to read a PNG
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135 file.
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136
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137 Setup
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138
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139 You will want to do the I/O initialization(*) before you get into libpng,
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140 so if it doesn't work, you don't have much to undo. Of course, you
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141 will also want to insure that you are, in fact, dealing with a PNG
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142 file. Libpng provides a simple check to see if a file is a PNG file.
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143 To use it, pass in the first 1 to 8 bytes of the file to the function
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144 png_sig_cmp(), and it will return 0 if the bytes match the corresponding
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145 bytes of the PNG signature, or nonzero otherwise. Of course, the more bytes
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146 you pass in, the greater the accuracy of the prediction.
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147
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148 If you are intending to keep the file pointer open for use in libpng,
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149 you must ensure you don't read more than 8 bytes from the beginning
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150 of the file, and you also have to make a call to png_set_sig_bytes_read()
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151 with the number of bytes you read from the beginning. Libpng will
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152 then only check the bytes (if any) that your program didn't read.
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153
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154 (*): If you are not using the standard I/O functions, you will need
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155 to replace them with custom functions. See the discussion under
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156 Customizing libpng.
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157
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158
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159 FILE *fp = fopen(file_name, "rb");
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160 if (!fp)
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161 {
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162 return (ERROR);
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163 }
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164 fread(header, 1, number, fp);
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165 is_png = !png_sig_cmp(header, 0, number);
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166 if (!is_png)
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167 {
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168 return (NOT_PNG);
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169 }
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170
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171
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172 Next, png_struct and png_info need to be allocated and initialized. In
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173 order to ensure that the size of these structures is correct even with a
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174 dynamically linked libpng, there are functions to initialize and
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175 allocate the structures. We also pass the library version, optional
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176 pointers to error handling functions, and a pointer to a data struct for
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177 use by the error functions, if necessary (the pointer and functions can
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178 be NULL if the default error handlers are to be used). See the section
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179 on Changes to Libpng below regarding the old initialization functions.
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180 The structure allocation functions quietly return NULL if they fail to
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181 create the structure, so your application should check for that.
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182
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183 png_structp png_ptr = png_create_read_struct
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184 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
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185 user_error_fn, user_warning_fn);
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186 if (!png_ptr)
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187 return (ERROR);
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188
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189 png_infop info_ptr = png_create_info_struct(png_ptr);
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190 if (!info_ptr)
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191 {
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192 png_destroy_read_struct(&png_ptr,
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193 (png_infopp)NULL, (png_infopp)NULL);
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194 return (ERROR);
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195 }
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196
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197 png_infop end_info = png_create_info_struct(png_ptr);
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198 if (!end_info)
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199 {
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200 png_destroy_read_struct(&png_ptr, &info_ptr,
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201 (png_infopp)NULL);
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202 return (ERROR);
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203 }
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204
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205 If you want to use your own memory allocation routines,
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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206 define PNG_USER_MEM_SUPPORTED and use
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
207 png_create_read_struct_2() instead of png_create_read_struct():
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208
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209 png_structp png_ptr = png_create_read_struct_2
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210 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
211 user_error_fn, user_warning_fn, (png_voidp)
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212 user_mem_ptr, user_malloc_fn, user_free_fn);
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213
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diff changeset
214 The error handling routines passed to png_create_read_struct()
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diff changeset
215 and the memory alloc/free routines passed to png_create_struct_2()
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diff changeset
216 are only necessary if you are not using the libpng supplied error
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diff changeset
217 handling and memory alloc/free functions.
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218
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219 When libpng encounters an error, it expects to longjmp back
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220 to your routine. Therefore, you will need to call setjmp and pass
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diff changeset
221 your png_jmpbuf(png_ptr). If you read the file from different
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222 routines, you will need to update the jmpbuf field every time you enter
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diff changeset
223 a new routine that will call a png_*() function.
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224
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225 See your documentation of setjmp/longjmp for your compiler for more
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diff changeset
226 information on setjmp/longjmp. See the discussion on libpng error
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
227 handling in the Customizing Libpng section below for more information
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228 on the libpng error handling. If an error occurs, and libpng longjmp's
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diff changeset
229 back to your setjmp, you will want to call png_destroy_read_struct() to
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diff changeset
230 free any memory.
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231
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232 if (setjmp(png_jmpbuf(png_ptr)))
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233 {
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
234 png_destroy_read_struct(&png_ptr, &info_ptr,
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diff changeset
235 &end_info);
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
236 fclose(fp);
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diff changeset
237 return (ERROR);
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238 }
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239
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240 If you would rather avoid the complexity of setjmp/longjmp issues,
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
241 you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
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diff changeset
242 errors will result in a call to PNG_ABORT() which defaults to abort().
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243
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diff changeset
244 Now you need to set up the input code. The default for libpng is to
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diff changeset
245 use the C function fread(). If you use this, you will need to pass a
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diff changeset
246 valid FILE * in the function png_init_io(). Be sure that the file is
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diff changeset
247 opened in binary mode. If you wish to handle reading data in another
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
248 way, you need not call the png_init_io() function, but you must then
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
249 implement the libpng I/O methods discussed in the Customizing Libpng
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
250 section below.
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251
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252 png_init_io(png_ptr, fp);
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253
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254 If you had previously opened the file and read any of the signature from
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diff changeset
255 the beginning in order to see if this was a PNG file, you need to let
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
256 libpng know that there are some bytes missing from the start of the file.
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257
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258 png_set_sig_bytes(png_ptr, number);
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259
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
260 Setting up callback code
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261
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262 You can set up a callback function to handle any unknown chunks in the
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diff changeset
263 input stream. You must supply the function
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264
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265 read_chunk_callback(png_ptr ptr,
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
266 png_unknown_chunkp chunk);
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267 {
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268 /* The unknown chunk structure contains your
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diff changeset
269 chunk data, along with similar data for any other
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diff changeset
270 unknown chunks: */
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271
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272 png_byte name[5];
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diff changeset
273 png_byte *data;
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diff changeset
274 png_size_t size;
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275
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276 /* Note that libpng has already taken care of
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
277 the CRC handling */
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278
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279 /* put your code here. Search for your chunk in the
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
280 unknown chunk structure, process it, and return one
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
281 of the following: */
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282
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
283 return (-n); /* chunk had an error */
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
284 return (0); /* did not recognize */
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
285 return (n); /* success */
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diff changeset
286 }
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diff changeset
287
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
288 (You can give your function another name that you like instead of
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
289 "read_chunk_callback")
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diff changeset
290
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
291 To inform libpng about your function, use
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292
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diff changeset
293 png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
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diff changeset
294 read_chunk_callback);
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295
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diff changeset
296 This names not only the callback function, but also a user pointer that
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diff changeset
297 you can retrieve with
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diff changeset
298
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
299 png_get_user_chunk_ptr(png_ptr);
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diff changeset
300
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
301 If you call the png_set_read_user_chunk_fn() function, then all unknown
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
302 chunks will be saved when read, in case your callback function will need
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
303 one or more of them. This behavior can be changed with the
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
304 png_set_keep_unknown_chunks() function, described below.
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diff changeset
305
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
306 At this point, you can set up a callback function that will be
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
307 called after each row has been read, which you can use to control
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
308 a progress meter or the like. It's demonstrated in pngtest.c.
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
309 You must supply a function
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diff changeset
310
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
311 void read_row_callback(png_ptr ptr, png_uint_32 row,
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
312 int pass);
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
313 {
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
314 /* put your code here */
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
315 }
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
316
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
317 (You can give it another name that you like instead of "read_row_callback")
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
318
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
319 To inform libpng about your function, use
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mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
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diff changeset
320
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
321 png_set_read_status_fn(png_ptr, read_row_callback);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
322
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
323 Width and height limits
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
324
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
325 The PNG specification allows the width and height of an image to be as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
326 large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
327 Since very few applications really need to process such large images,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
328 we have imposed an arbitrary 1-million limit on rows and columns.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
329 Larger images will be rejected immediately with a png_error() call. If
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
330 you wish to override this limit, you can use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
331
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
332 png_set_user_limits(png_ptr, width_max, height_max);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
333
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
334 to set your own limits, or use width_max = height_max = 0x7fffffffL
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
335 to allow all valid dimensions (libpng may reject some very large images
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
336 anyway because of potential buffer overflow conditions).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
337
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
338 You should put this statement after you create the PNG structure and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
339 before calling png_read_info(), png_read_png(), or png_process_data().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
340 If you need to retrieve the limits that are being applied, use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
341
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
342 width_max = png_get_user_width_max(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
343 height_max = png_get_user_height_max(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
344
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
345 Unknown-chunk handling
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
346
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
347 Now you get to set the way the library processes unknown chunks in the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
348 input PNG stream. Both known and unknown chunks will be read. Normal
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
349 behavior is that known chunks will be parsed into information in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
350 various info_ptr members while unknown chunks will be discarded. To change
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
351 this, you can call:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
352
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
353 png_set_keep_unknown_chunks(png_ptr, keep,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
354 chunk_list, num_chunks);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
355 keep - 0: default unknown chunk handling
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
356 1: ignore; do not keep
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
357 2: keep only if safe-to-copy
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
358 3: keep even if unsafe-to-copy
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
359 You can use these definitions:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
360 PNG_HANDLE_CHUNK_AS_DEFAULT 0
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
361 PNG_HANDLE_CHUNK_NEVER 1
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
362 PNG_HANDLE_CHUNK_IF_SAFE 2
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
363 PNG_HANDLE_CHUNK_ALWAYS 3
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
364 chunk_list - list of chunks affected (a byte string,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
365 five bytes per chunk, NULL or '\0' if
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
366 num_chunks is 0)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
367 num_chunks - number of chunks affected; if 0, all
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
368 unknown chunks are affected. If nonzero,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
369 only the chunks in the list are affected
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
370
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
371 Unknown chunks declared in this way will be saved as raw data onto a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
372 list of png_unknown_chunk structures. If a chunk that is normally
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
373 known to libpng is named in the list, it will be handled as unknown,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
374 according to the "keep" directive. If a chunk is named in successive
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
375 instances of png_set_keep_unknown_chunks(), the final instance will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
376 take precedence. The IHDR and IEND chunks should not be named in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
377 chunk_list; if they are, libpng will process them normally anyway.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
378
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
379 Here is an example of the usage of png_set_keep_unknown_chunks(),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
380 where the private "vpAg" chunk will later be processed by a user chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
381 callback function:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
382
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
383 png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
384
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
385 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
386 png_byte unused_chunks[]=
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
387 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
388 104, 73, 83, 84, (png_byte) '\0', /* hIST */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
389 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
390 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
391 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
392 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
393 116, 73, 77, 69, (png_byte) '\0', /* tIME */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
394 };
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
395 #endif
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
396
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
397 ...
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
398
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
399 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
400 /* ignore all unknown chunks: */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
401 png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
402 /* except for vpAg: */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
403 png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
404 /* also ignore unused known chunks: */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
405 png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
406 (int)sizeof(unused_chunks)/5);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
407 #endif
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
408
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
409
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
410 The high-level read interface
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
411
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
412 At this point there are two ways to proceed; through the high-level
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
413 read interface, or through a sequence of low-level read operations.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
414 You can use the high-level interface if (a) you are willing to read
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
415 the entire image into memory, and (b) the input transformations
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
416 you want to do are limited to the following set:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
417
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
418 PNG_TRANSFORM_IDENTITY No transformation
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
419 PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
420 8 bits
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
421 PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
422 PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
423 samples to bytes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
424 PNG_TRANSFORM_PACKSWAP Change order of packed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
425 pixels to LSB first
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
426 PNG_TRANSFORM_EXPAND Perform set_expand()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
427 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
428 PNG_TRANSFORM_SHIFT Normalize pixels to the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
429 sBIT depth
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
430 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
431 to BGRA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
432 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
433 to AG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
434 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
435 to transparency
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
436 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
437
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
438 (This excludes setting a background color, doing gamma transformation,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
439 dithering, and setting filler.) If this is the case, simply do this:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
440
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
441 png_read_png(png_ptr, info_ptr, png_transforms, NULL)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
442
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
443 where png_transforms is an integer containing the bitwise OR of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
444 some set of transformation flags. This call is equivalent to png_read_info(),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
445 followed the set of transformations indicated by the transform mask,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
446 then png_read_image(), and finally png_read_end().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
447
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
448 (The final parameter of this call is not yet used. Someday it might point
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
449 to transformation parameters required by some future input transform.)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
450
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
451 You must use png_transforms and not call any png_set_transform() functions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
452 when you use png_read_png().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
453
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
454 After you have called png_read_png(), you can retrieve the image data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
455 with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
456
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
457 row_pointers = png_get_rows(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
458
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
459 where row_pointers is an array of pointers to the pixel data for each row:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
460
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
461 png_bytep row_pointers[height];
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
462
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
463 If you know your image size and pixel size ahead of time, you can allocate
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
464 row_pointers prior to calling png_read_png() with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
465
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
466 if (height > PNG_UINT_32_MAX/png_sizeof(png_byte))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
467 png_error (png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
468 "Image is too tall to process in memory");
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
469 if (width > PNG_UINT_32_MAX/pixel_size)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
470 png_error (png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
471 "Image is too wide to process in memory");
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
472 row_pointers = png_malloc(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
473 height*png_sizeof(png_bytep));
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
474 for (int i=0; i<height, i++)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
475 row_pointers[i]=png_malloc(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
476 width*pixel_size);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
477 png_set_rows(png_ptr, info_ptr, &row_pointers);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
478
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
479 Alternatively you could allocate your image in one big block and define
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
480 row_pointers[i] to point into the proper places in your block.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
481
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
482 If you use png_set_rows(), the application is responsible for freeing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
483 row_pointers (and row_pointers[i], if they were separately allocated).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
484
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
485 If you don't allocate row_pointers ahead of time, png_read_png() will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
486 do it, and it'll be free'ed when you call png_destroy_*().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
487
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
488 The low-level read interface
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
489
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
490 If you are going the low-level route, you are now ready to read all
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
491 the file information up to the actual image data. You do this with a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
492 call to png_read_info().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
493
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
494 png_read_info(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
495
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
496 This will process all chunks up to but not including the image data.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
497
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
498 Querying the info structure
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
499
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
500 Functions are used to get the information from the info_ptr once it
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
501 has been read. Note that these fields may not be completely filled
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
502 in until png_read_end() has read the chunk data following the image.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
503
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
504 png_get_IHDR(png_ptr, info_ptr, &width, &height,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
505 &bit_depth, &color_type, &interlace_type,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
506 &compression_type, &filter_method);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
507
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
508 width - holds the width of the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
509 in pixels (up to 2^31).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
510 height - holds the height of the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
511 in pixels (up to 2^31).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
512 bit_depth - holds the bit depth of one of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
513 image channels. (valid values are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
514 1, 2, 4, 8, 16 and depend also on
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
515 the color_type. See also
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
516 significant bits (sBIT) below).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
517 color_type - describes which color/alpha channels
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
518 are present.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
519 PNG_COLOR_TYPE_GRAY
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
520 (bit depths 1, 2, 4, 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
521 PNG_COLOR_TYPE_GRAY_ALPHA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
522 (bit depths 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
523 PNG_COLOR_TYPE_PALETTE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
524 (bit depths 1, 2, 4, 8)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
525 PNG_COLOR_TYPE_RGB
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
526 (bit_depths 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
527 PNG_COLOR_TYPE_RGB_ALPHA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
528 (bit_depths 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
529
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
530 PNG_COLOR_MASK_PALETTE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
531 PNG_COLOR_MASK_COLOR
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
532 PNG_COLOR_MASK_ALPHA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
533
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
534 filter_method - (must be PNG_FILTER_TYPE_BASE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
535 for PNG 1.0, and can also be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
536 PNG_INTRAPIXEL_DIFFERENCING if
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
537 the PNG datastream is embedded in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
538 a MNG-1.0 datastream)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
539 compression_type - (must be PNG_COMPRESSION_TYPE_BASE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
540 for PNG 1.0)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
541 interlace_type - (PNG_INTERLACE_NONE or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
542 PNG_INTERLACE_ADAM7)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
543 Any or all of interlace_type, compression_type, of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
544 filter_method can be NULL if you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
545 not interested in their values.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
546
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
547 channels = png_get_channels(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
548 channels - number of channels of info for the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
549 color type (valid values are 1 (GRAY,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
550 PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
551 4 (RGB_ALPHA or RGB + filler byte))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
552 rowbytes = png_get_rowbytes(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
553 rowbytes - number of bytes needed to hold a row
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
554
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
555 signature = png_get_signature(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
556 signature - holds the signature read from the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
557 file (if any). The data is kept in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
558 the same offset it would be if the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
559 whole signature were read (i.e. if an
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
560 application had already read in 4
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
561 bytes of signature before starting
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
562 libpng, the remaining 4 bytes would
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
563 be in signature[4] through signature[7]
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
564 (see png_set_sig_bytes())).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
565
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
566
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
567 width = png_get_image_width(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
568 info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
569 height = png_get_image_height(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
570 info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
571 bit_depth = png_get_bit_depth(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
572 info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
573 color_type = png_get_color_type(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
574 info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
575 filter_method = png_get_filter_type(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
576 info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
577 compression_type = png_get_compression_type(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
578 info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
579 interlace_type = png_get_interlace_type(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
580 info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
581
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
582
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
583 These are also important, but their validity depends on whether the chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
584 has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
585 png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
586 data has been read, or zero if it is missing. The parameters to the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
587 png_get_<chunk> are set directly if they are simple data types, or a pointer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
588 into the info_ptr is returned for any complex types.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
589
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
590 png_get_PLTE(png_ptr, info_ptr, &palette,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
591 &num_palette);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
592 palette - the palette for the file
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
593 (array of png_color)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
594 num_palette - number of entries in the palette
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
595
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
596 png_get_gAMA(png_ptr, info_ptr, &gamma);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
597 gamma - the gamma the file is written
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
598 at (PNG_INFO_gAMA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
599
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
600 png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
601 srgb_intent - the rendering intent (PNG_INFO_sRGB)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
602 The presence of the sRGB chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
603 means that the pixel data is in the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
604 sRGB color space. This chunk also
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
605 implies specific values of gAMA and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
606 cHRM.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
607
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
608 png_get_iCCP(png_ptr, info_ptr, &name,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
609 &compression_type, &profile, &proflen);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
610 name - The profile name.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
611 compression - The compression type; always
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
612 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
613 You may give NULL to this argument to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
614 ignore it.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
615 profile - International Color Consortium color
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
616 profile data. May contain NULs.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
617 proflen - length of profile data in bytes.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
618
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
619 png_get_sBIT(png_ptr, info_ptr, &sig_bit);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
620 sig_bit - the number of significant bits for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
621 (PNG_INFO_sBIT) each of the gray,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
622 red, green, and blue channels,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
623 whichever are appropriate for the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
624 given color type (png_color_16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
625
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
626 png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
627 &trans_values);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
628 trans - array of transparent entries for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
629 palette (PNG_INFO_tRNS)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
630 trans_values - graylevel or color sample values of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
631 the single transparent color for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
632 non-paletted images (PNG_INFO_tRNS)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
633 num_trans - number of transparent entries
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
634 (PNG_INFO_tRNS)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
635
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
636 png_get_hIST(png_ptr, info_ptr, &hist);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
637 (PNG_INFO_hIST)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
638 hist - histogram of palette (array of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
639 png_uint_16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
640
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
641 png_get_tIME(png_ptr, info_ptr, &mod_time);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
642 mod_time - time image was last modified
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
643 (PNG_VALID_tIME)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
644
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
645 png_get_bKGD(png_ptr, info_ptr, &background);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
646 background - background color (PNG_VALID_bKGD)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
647 valid 16-bit red, green and blue
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
648 values, regardless of color_type
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
649
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
650 num_comments = png_get_text(png_ptr, info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
651 &text_ptr, &num_text);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
652 num_comments - number of comments
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
653 text_ptr - array of png_text holding image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
654 comments
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
655 text_ptr[i].compression - type of compression used
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
656 on "text" PNG_TEXT_COMPRESSION_NONE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
657 PNG_TEXT_COMPRESSION_zTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
658 PNG_ITXT_COMPRESSION_NONE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
659 PNG_ITXT_COMPRESSION_zTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
660 text_ptr[i].key - keyword for comment. Must contain
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
661 1-79 characters.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
662 text_ptr[i].text - text comments for current
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
663 keyword. Can be empty.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
664 text_ptr[i].text_length - length of text string,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
665 after decompression, 0 for iTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
666 text_ptr[i].itxt_length - length of itxt string,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
667 after decompression, 0 for tEXt/zTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
668 text_ptr[i].lang - language of comment (empty
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
669 string for unknown).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
670 text_ptr[i].lang_key - keyword in UTF-8
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
671 (empty string for unknown).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
672 num_text - number of comments (same as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
673 num_comments; you can put NULL here
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
674 to avoid the duplication)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
675 Note while png_set_text() will accept text, language,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
676 and translated keywords that can be NULL pointers, the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
677 structure returned by png_get_text will always contain
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
678 regular zero-terminated C strings. They might be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
679 empty strings but they will never be NULL pointers.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
680
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
681 num_spalettes = png_get_sPLT(png_ptr, info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
682 &palette_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
683 palette_ptr - array of palette structures holding
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
684 contents of one or more sPLT chunks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
685 read.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
686 num_spalettes - number of sPLT chunks read.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
687
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
688 png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
689 &unit_type);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
690 offset_x - positive offset from the left edge
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
691 of the screen
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
692 offset_y - positive offset from the top edge
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
693 of the screen
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
694 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
695
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
696 png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
697 &unit_type);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
698 res_x - pixels/unit physical resolution in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
699 x direction
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
700 res_y - pixels/unit physical resolution in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
701 x direction
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
702 unit_type - PNG_RESOLUTION_UNKNOWN,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
703 PNG_RESOLUTION_METER
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
704
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
705 png_get_sCAL(png_ptr, info_ptr, &unit, &width,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
706 &height)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
707 unit - physical scale units (an integer)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
708 width - width of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
709 height - height of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
710 (width and height are doubles)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
711
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
712 png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
713 &height)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
714 unit - physical scale units (an integer)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
715 width - width of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
716 height - height of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
717 (width and height are strings like "2.54")
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
718
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
719 num_unknown_chunks = png_get_unknown_chunks(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
720 info_ptr, &unknowns)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
721 unknowns - array of png_unknown_chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
722 structures holding unknown chunks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
723 unknowns[i].name - name of unknown chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
724 unknowns[i].data - data of unknown chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
725 unknowns[i].size - size of unknown chunk's data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
726 unknowns[i].location - position of chunk in file
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
727
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
728 The value of "i" corresponds to the order in which the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
729 chunks were read from the PNG file or inserted with the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
730 png_set_unknown_chunks() function.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
731
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
732 The data from the pHYs chunk can be retrieved in several convenient
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
733 forms:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
734
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
735 res_x = png_get_x_pixels_per_meter(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
736 info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
737 res_y = png_get_y_pixels_per_meter(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
738 info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
739 res_x_and_y = png_get_pixels_per_meter(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
740 info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
741 res_x = png_get_x_pixels_per_inch(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
742 info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
743 res_y = png_get_y_pixels_per_inch(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
744 info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
745 res_x_and_y = png_get_pixels_per_inch(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
746 info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
747 aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
748 info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
749
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
750 (Each of these returns 0 [signifying "unknown"] if
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
751 the data is not present or if res_x is 0;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
752 res_x_and_y is 0 if res_x != res_y)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
753
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
754 The data from the oFFs chunk can be retrieved in several convenient
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
755 forms:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
756
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
757 x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
758 y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
759 x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
760 y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
761
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
762 (Each of these returns 0 [signifying "unknown" if both
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
763 x and y are 0] if the data is not present or if the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
764 chunk is present but the unit is the pixel)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
765
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
766 For more information, see the png_info definition in png.h and the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
767 PNG specification for chunk contents. Be careful with trusting
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
768 rowbytes, as some of the transformations could increase the space
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
769 needed to hold a row (expand, filler, gray_to_rgb, etc.).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
770 See png_read_update_info(), below.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
771
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
772 A quick word about text_ptr and num_text. PNG stores comments in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
773 keyword/text pairs, one pair per chunk, with no limit on the number
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
774 of text chunks, and a 2^31 byte limit on their size. While there are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
775 suggested keywords, there is no requirement to restrict the use to these
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
776 strings. It is strongly suggested that keywords and text be sensible
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
777 to humans (that's the point), so don't use abbreviations. Non-printing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
778 symbols are not allowed. See the PNG specification for more details.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
779 There is also no requirement to have text after the keyword.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
780
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
781 Keywords should be limited to 79 Latin-1 characters without leading or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
782 trailing spaces, but non-consecutive spaces are allowed within the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
783 keyword. It is possible to have the same keyword any number of times.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
784 The text_ptr is an array of png_text structures, each holding a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
785 pointer to a language string, a pointer to a keyword and a pointer to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
786 a text string. The text string, language code, and translated
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
787 keyword may be empty or NULL pointers. The keyword/text
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
788 pairs are put into the array in the order that they are received.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
789 However, some or all of the text chunks may be after the image, so, to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
790 make sure you have read all the text chunks, don't mess with these
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
791 until after you read the stuff after the image. This will be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
792 mentioned again below in the discussion that goes with png_read_end().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
793
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
794 Input transformations
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
795
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
796 After you've read the header information, you can set up the library
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
797 to handle any special transformations of the image data. The various
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
798 ways to transform the data will be described in the order that they
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
799 should occur. This is important, as some of these change the color
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
800 type and/or bit depth of the data, and some others only work on
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
801 certain color types and bit depths. Even though each transformation
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
802 checks to see if it has data that it can do something with, you should
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
803 make sure to only enable a transformation if it will be valid for the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
804 data. For example, don't swap red and blue on grayscale data.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
805
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
806 The colors used for the background and transparency values should be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
807 supplied in the same format/depth as the current image data. They
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
808 are stored in the same format/depth as the image data in a bKGD or tRNS
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
809 chunk, so this is what libpng expects for this data. The colors are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
810 transformed to keep in sync with the image data when an application
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
811 calls the png_read_update_info() routine (see below).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
812
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
813 Data will be decoded into the supplied row buffers packed into bytes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
814 unless the library has been told to transform it into another format.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
815 For example, 4 bit/pixel paletted or grayscale data will be returned
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
816 2 pixels/byte with the leftmost pixel in the high-order bits of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
817 byte, unless png_set_packing() is called. 8-bit RGB data will be stored
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
818 in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
819 is called to insert filler bytes, either before or after each RGB triplet.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
820 16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
821 byte of the color value first, unless png_set_strip_16() is called to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
822 transform it to regular RGB RGB triplets, or png_set_filler() or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
823 png_set_add alpha() is called to insert filler bytes, either before or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
824 after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
825 be modified with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
826 png_set_filler(), png_set_add_alpha(), or png_set_strip_16().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
827
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
828 The following code transforms grayscale images of less than 8 to 8 bits,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
829 changes paletted images to RGB, and adds a full alpha channel if there is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
830 transparency information in a tRNS chunk. This is most useful on
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
831 grayscale images with bit depths of 2 or 4 or if there is a multiple-image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
832 viewing application that wishes to treat all images in the same way.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
833
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
834 if (color_type == PNG_COLOR_TYPE_PALETTE)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
835 png_set_palette_to_rgb(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
836
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
837 if (color_type == PNG_COLOR_TYPE_GRAY &&
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
838 bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
839
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
840 if (png_get_valid(png_ptr, info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
841 PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
842
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
843 These three functions are actually aliases for png_set_expand(), added
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
844 in libpng version 1.0.4, with the function names expanded to improve code
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
845 readability. In some future version they may actually do different
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
846 things.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
847
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
848 As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
849 added. It expands the sample depth without changing tRNS to alpha.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
850 At the same time, png_set_gray_1_2_4_to_8() was deprecated, and it
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
851 will be removed from a future version.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
852
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
853
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
854 PNG can have files with 16 bits per channel. If you only can handle
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
855 8 bits per channel, this will strip the pixels down to 8 bit.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
856
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
857 if (bit_depth == 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
858 png_set_strip_16(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
859
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
860 If, for some reason, you don't need the alpha channel on an image,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
861 and you want to remove it rather than combining it with the background
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
862 (but the image author certainly had in mind that you *would* combine
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
863 it with the background, so that's what you should probably do):
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
864
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
865 if (color_type & PNG_COLOR_MASK_ALPHA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
866 png_set_strip_alpha(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
867
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
868 In PNG files, the alpha channel in an image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
869 is the level of opacity. If you need the alpha channel in an image to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
870 be the level of transparency instead of opacity, you can invert the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
871 alpha channel (or the tRNS chunk data) after it's read, so that 0 is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
872 fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
873 images) is fully transparent, with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
874
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
875 png_set_invert_alpha(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
876
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
877 PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
878 they can, resulting in, for example, 8 pixels per byte for 1 bit
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
879 files. This code expands to 1 pixel per byte without changing the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
880 values of the pixels:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
881
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
882 if (bit_depth < 8)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
883 png_set_packing(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
884
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
885 PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
886 stored in a PNG image have been "scaled" or "shifted" up to the next
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
887 higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
888 8 bits/sample in the range [0, 255]). However, it is also possible to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
889 convert the PNG pixel data back to the original bit depth of the image.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
890 This call reduces the pixels back down to the original bit depth:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
891
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
892 png_color_8p sig_bit;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
893
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
894 if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
895 png_set_shift(png_ptr, sig_bit);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
896
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
897 PNG files store 3-color pixels in red, green, blue order. This code
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
898 changes the storage of the pixels to blue, green, red:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
899
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
900 if (color_type == PNG_COLOR_TYPE_RGB ||
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
901 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
902 png_set_bgr(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
903
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
904 PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
905 into 4 or 8 bytes for windowing systems that need them in this format:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
906
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
907 if (color_type == PNG_COLOR_TYPE_RGB)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
908 png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
909
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
910 where "filler" is the 8 or 16-bit number to fill with, and the location is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
911 either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
912 you want the filler before the RGB or after. This transformation
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
913 does not affect images that already have full alpha channels. To add an
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
914 opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
915 will generate RGBA pixels.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
916
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
917 Note that png_set_filler() does not change the color type. If you want
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
918 to do that, you can add a true alpha channel with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
919
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
920 if (color_type == PNG_COLOR_TYPE_RGB ||
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
921 color_type == PNG_COLOR_TYPE_GRAY)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
922 png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
923
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
924 where "filler" contains the alpha value to assign to each pixel.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
925 This function was added in libpng-1.2.7.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
926
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
927 If you are reading an image with an alpha channel, and you need the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
928 data as ARGB instead of the normal PNG format RGBA:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
929
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
930 if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
931 png_set_swap_alpha(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
932
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
933 For some uses, you may want a grayscale image to be represented as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
934 RGB. This code will do that conversion:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
935
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
936 if (color_type == PNG_COLOR_TYPE_GRAY ||
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
937 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
938 png_set_gray_to_rgb(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
939
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
940 Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
941 with alpha.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
942
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
943 if (color_type == PNG_COLOR_TYPE_RGB ||
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
944 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
945 png_set_rgb_to_gray_fixed(png_ptr, error_action,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
946 int red_weight, int green_weight);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
947
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
948 error_action = 1: silently do the conversion
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
949 error_action = 2: issue a warning if the original
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
950 image has any pixel where
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
951 red != green or red != blue
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
952 error_action = 3: issue an error and abort the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
953 conversion if the original
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
954 image has any pixel where
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
955 red != green or red != blue
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
956
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
957 red_weight: weight of red component times 100000
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
958 green_weight: weight of green component times 100000
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
959 If either weight is negative, default
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
960 weights (21268, 71514) are used.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
961
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
962 If you have set error_action = 1 or 2, you can
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
963 later check whether the image really was gray, after processing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
964 the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
965 It will return a png_byte that is zero if the image was gray or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
966 1 if there were any non-gray pixels. bKGD and sBIT data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
967 will be silently converted to grayscale, using the green channel
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
968 data, regardless of the error_action setting.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
969
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
970 With red_weight+green_weight<=100000,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
971 the normalized graylevel is computed:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
972
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
973 int rw = red_weight * 65536;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
974 int gw = green_weight * 65536;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
975 int bw = 65536 - (rw + gw);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
976 gray = (rw*red + gw*green + bw*blue)/65536;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
977
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
978 The default values approximate those recommended in the Charles
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
979 Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
980 Copyright (c) 1998-01-04 Charles Poynton <poynton at inforamp.net>
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
981
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
982 Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
983
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
984 Libpng approximates this with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
985
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
986 Y = 0.21268 * R + 0.7151 * G + 0.07217 * B
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
987
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
988 which can be expressed with integers as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
989
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
990 Y = (6969 * R + 23434 * G + 2365 * B)/32768
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
991
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
992 The calculation is done in a linear colorspace, if the image gamma
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
993 is known.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
994
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
995 If you have a grayscale and you are using png_set_expand_depth(),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
996 png_set_expand(), or png_set_gray_to_rgb to change to truecolor or to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
997 a higher bit-depth, you must either supply the background color as a gray
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
998 value at the original file bit-depth (need_expand = 1) or else supply the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
999 background color as an RGB triplet at the final, expanded bit depth
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1000 (need_expand = 0). Similarly, if you are reading a paletted image, you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1001 must either supply the background color as a palette index (need_expand = 1)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1002 or as an RGB triplet that may or may not be in the palette (need_expand = 0).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1003
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1004 png_color_16 my_background;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1005 png_color_16p image_background;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1006
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1007 if (png_get_bKGD(png_ptr, info_ptr, &image_background))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1008 png_set_background(png_ptr, image_background,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1009 PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1010 else
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1011 png_set_background(png_ptr, &my_background,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1012 PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1013
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1014 The png_set_background() function tells libpng to composite images
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1015 with alpha or simple transparency against the supplied background
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1016 color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1017 you may use this color, or supply another color more suitable for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1018 the current display (e.g., the background color from a web page). You
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1019 need to tell libpng whether the color is in the gamma space of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1020 display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1021 (PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1022 that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1023 know why anyone would use this, but it's here).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1024
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1025 To properly display PNG images on any kind of system, the application needs
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1026 to know what the display gamma is. Ideally, the user will know this, and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1027 the application will allow them to set it. One method of allowing the user
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1028 to set the display gamma separately for each system is to check for a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1029 SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1030 correctly set.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1031
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1032 Note that display_gamma is the overall gamma correction required to produce
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1033 pleasing results, which depends on the lighting conditions in the surrounding
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1034 environment. In a dim or brightly lit room, no compensation other than
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1035 the physical gamma exponent of the monitor is needed, while in a dark room
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1036 a slightly smaller exponent is better.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1037
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1038 double gamma, screen_gamma;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1039
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1040 if (/* We have a user-defined screen
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1041 gamma value */)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1042 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1043 screen_gamma = user_defined_screen_gamma;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1044 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1045 /* One way that applications can share the same
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1046 screen gamma value */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1047 else if ((gamma_str = getenv("SCREEN_GAMMA"))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1048 != NULL)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1049 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1050 screen_gamma = (double)atof(gamma_str);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1051 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1052 /* If we don't have another value */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1053 else
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1054 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1055 screen_gamma = 2.2; /* A good guess for a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1056 PC monitor in a bright office or a dim room */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1057 screen_gamma = 2.0; /* A good guess for a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1058 PC monitor in a dark room */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1059 screen_gamma = 1.7 or 1.0; /* A good
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1060 guess for Mac systems */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1061 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1062
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1063 The png_set_gamma() function handles gamma transformations of the data.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1064 Pass both the file gamma and the current screen_gamma. If the file does
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1065 not have a gamma value, you can pass one anyway if you have an idea what
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1066 it is (usually 0.45455 is a good guess for GIF images on PCs). Note
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1067 that file gammas are inverted from screen gammas. See the discussions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1068 on gamma in the PNG specification for an excellent description of what
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1069 gamma is, and why all applications should support it. It is strongly
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1070 recommended that PNG viewers support gamma correction.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1071
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1072 if (png_get_gAMA(png_ptr, info_ptr, &gamma))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1073 png_set_gamma(png_ptr, screen_gamma, gamma);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1074 else
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1075 png_set_gamma(png_ptr, screen_gamma, 0.45455);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1076
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1077 If you need to reduce an RGB file to a paletted file, or if a paletted
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1078 file has more entries then will fit on your screen, png_set_dither()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1079 will do that. Note that this is a simple match dither that merely
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1080 finds the closest color available. This should work fairly well with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1081 optimized palettes, and fairly badly with linear color cubes. If you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1082 pass a palette that is larger then maximum_colors, the file will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1083 reduce the number of colors in the palette so it will fit into
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1084 maximum_colors. If there is a histogram, it will use it to make
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1085 more intelligent choices when reducing the palette. If there is no
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1086 histogram, it may not do as good a job.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1087
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1088 if (color_type & PNG_COLOR_MASK_COLOR)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1089 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1090 if (png_get_valid(png_ptr, info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1091 PNG_INFO_PLTE))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1092 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1093 png_uint_16p histogram = NULL;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1094
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1095 png_get_hIST(png_ptr, info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1096 &histogram);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1097 png_set_dither(png_ptr, palette, num_palette,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1098 max_screen_colors, histogram, 1);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1099 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1100 else
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1101 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1102 png_color std_color_cube[MAX_SCREEN_COLORS] =
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1103 { ... colors ... };
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1104
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1105 png_set_dither(png_ptr, std_color_cube,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1106 MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1107 NULL,0);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1108 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1109 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1110
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1111 PNG files describe monochrome as black being zero and white being one.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1112 The following code will reverse this (make black be one and white be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1113 zero):
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1114
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1115 if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1116 png_set_invert_mono(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1117
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1118 This function can also be used to invert grayscale and gray-alpha images:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1119
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1120 if (color_type == PNG_COLOR_TYPE_GRAY ||
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1121 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1122 png_set_invert_mono(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1123
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1124 PNG files store 16 bit pixels in network byte order (big-endian,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1125 ie. most significant bits first). This code changes the storage to the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1126 other way (little-endian, i.e. least significant bits first, the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1127 way PCs store them):
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1128
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1129 if (bit_depth == 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1130 png_set_swap(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1131
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1132 If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1133 need to change the order the pixels are packed into bytes, you can use:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1134
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1135 if (bit_depth < 8)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1136 png_set_packswap(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1137
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1138 Finally, you can write your own transformation function if none of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1139 the existing ones meets your needs. This is done by setting a callback
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1140 with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1141
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1142 png_set_read_user_transform_fn(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1143 read_transform_fn);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1144
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1145 You must supply the function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1146
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1147 void read_transform_fn(png_ptr ptr, row_info_ptr
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1148 row_info, png_bytep data)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1149
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1150 See pngtest.c for a working example. Your function will be called
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1151 after all of the other transformations have been processed.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1152
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1153 You can also set up a pointer to a user structure for use by your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1154 callback function, and you can inform libpng that your transform
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1155 function will change the number of channels or bit depth with the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1156 function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1157
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1158 png_set_user_transform_info(png_ptr, user_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1159 user_depth, user_channels);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1160
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1161 The user's application, not libpng, is responsible for allocating and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1162 freeing any memory required for the user structure.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1163
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1164 You can retrieve the pointer via the function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1165 png_get_user_transform_ptr(). For example:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1166
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1167 voidp read_user_transform_ptr =
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1168 png_get_user_transform_ptr(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1169
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1170 The last thing to handle is interlacing; this is covered in detail below,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1171 but you must call the function here if you want libpng to handle expansion
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1172 of the interlaced image.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1173
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1174 number_of_passes = png_set_interlace_handling(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1175
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1176 After setting the transformations, libpng can update your png_info
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1177 structure to reflect any transformations you've requested with this
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1178 call. This is most useful to update the info structure's rowbytes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1179 field so you can use it to allocate your image memory. This function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1180 will also update your palette with the correct screen_gamma and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1181 background if these have been given with the calls above.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1182
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1183 png_read_update_info(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1184
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1185 After you call png_read_update_info(), you can allocate any
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1186 memory you need to hold the image. The row data is simply
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1187 raw byte data for all forms of images. As the actual allocation
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1188 varies among applications, no example will be given. If you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1189 are allocating one large chunk, you will need to build an
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1190 array of pointers to each row, as it will be needed for some
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1191 of the functions below.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1192
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1193 Reading image data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1194
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1195 After you've allocated memory, you can read the image data.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1196 The simplest way to do this is in one function call. If you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1197 allocating enough memory to hold the whole image, you can just
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1198 call png_read_image() and libpng will read in all the image data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1199 and put it in the memory area supplied. You will need to pass in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1200 an array of pointers to each row.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1201
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1202 This function automatically handles interlacing, so you don't need
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1203 to call png_set_interlace_handling() or call this function multiple
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1204 times, or any of that other stuff necessary with png_read_rows().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1205
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1206 png_read_image(png_ptr, row_pointers);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1207
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1208 where row_pointers is:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1209
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1210 png_bytep row_pointers[height];
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1211
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1212 You can point to void or char or whatever you use for pixels.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1213
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1214 If you don't want to read in the whole image at once, you can
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1215 use png_read_rows() instead. If there is no interlacing (check
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1216 interlace_type == PNG_INTERLACE_NONE), this is simple:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1217
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1218 png_read_rows(png_ptr, row_pointers, NULL,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1219 number_of_rows);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1220
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1221 where row_pointers is the same as in the png_read_image() call.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1222
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1223 If you are doing this just one row at a time, you can do this with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1224 a single row_pointer instead of an array of row_pointers:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1225
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1226 png_bytep row_pointer = row;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1227 png_read_row(png_ptr, row_pointer, NULL);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1228
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1229 If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1230 get somewhat harder. The only current (PNG Specification version 1.2)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1231 interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1232 is a somewhat complicated 2D interlace scheme, known as Adam7, that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1233 breaks down an image into seven smaller images of varying size, based
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1234 on an 8x8 grid.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1235
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1236 libpng can fill out those images or it can give them to you "as is".
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1237 If you want them filled out, there are two ways to do that. The one
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1238 mentioned in the PNG specification is to expand each pixel to cover
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1239 those pixels that have not been read yet (the "rectangle" method).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1240 This results in a blocky image for the first pass, which gradually
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1241 smooths out as more pixels are read. The other method is the "sparkle"
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1242 method, where pixels are drawn only in their final locations, with the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1243 rest of the image remaining whatever colors they were initialized to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1244 before the start of the read. The first method usually looks better,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1245 but tends to be slower, as there are more pixels to put in the rows.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1246
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1247 If you don't want libpng to handle the interlacing details, just call
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1248 png_read_rows() seven times to read in all seven images. Each of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1249 images is a valid image by itself, or they can all be combined on an
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1250 8x8 grid to form a single image (although if you intend to combine them
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1251 you would be far better off using the libpng interlace handling).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1252
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1253 The first pass will return an image 1/8 as wide as the entire image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1254 (every 8th column starting in column 0) and 1/8 as high as the original
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1255 (every 8th row starting in row 0), the second will be 1/8 as wide
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1256 (starting in column 4) and 1/8 as high (also starting in row 0). The
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1257 third pass will be 1/4 as wide (every 4th pixel starting in column 0) and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1258 1/8 as high (every 8th row starting in row 4), and the fourth pass will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1259 be 1/4 as wide and 1/4 as high (every 4th column starting in column 2,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1260 and every 4th row starting in row 0). The fifth pass will return an
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1261 image 1/2 as wide, and 1/4 as high (starting at column 0 and row 2),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1262 while the sixth pass will be 1/2 as wide and 1/2 as high as the original
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1263 (starting in column 1 and row 0). The seventh and final pass will be as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1264 wide as the original, and 1/2 as high, containing all of the odd
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1265 numbered scanlines. Phew!
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1266
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1267 If you want libpng to expand the images, call this before calling
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1268 png_start_read_image() or png_read_update_info():
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1269
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1270 if (interlace_type == PNG_INTERLACE_ADAM7)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1271 number_of_passes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1272 = png_set_interlace_handling(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1273
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1274 This will return the number of passes needed. Currently, this
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1275 is seven, but may change if another interlace type is added.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1276 This function can be called even if the file is not interlaced,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1277 where it will return one pass.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1278
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1279 If you are not going to display the image after each pass, but are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1280 going to wait until the entire image is read in, use the sparkle
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1281 effect. This effect is faster and the end result of either method
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1282 is exactly the same. If you are planning on displaying the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1283 after each pass, the "rectangle" effect is generally considered the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1284 better looking one.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1285
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1286 If you only want the "sparkle" effect, just call png_read_rows() as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1287 normal, with the third parameter NULL. Make sure you make pass over
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1288 the image number_of_passes times, and you don't change the data in the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1289 rows between calls. You can change the locations of the data, just
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1290 not the data. Each pass only writes the pixels appropriate for that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1291 pass, and assumes the data from previous passes is still valid.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1292
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1293 png_read_rows(png_ptr, row_pointers, NULL,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1294 number_of_rows);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1295
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1296 If you only want the first effect (the rectangles), do the same as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1297 before except pass the row buffer in the third parameter, and leave
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1298 the second parameter NULL.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1299
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1300 png_read_rows(png_ptr, NULL, row_pointers,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1301 number_of_rows);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1302
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1303 Finishing a sequential read
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1304
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1305 After you are finished reading the image through the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1306 low-level interface, you can finish reading the file. If you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1307 interested in comments or time, which may be stored either before or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1308 after the image data, you should pass the separate png_info struct if
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1309 you want to keep the comments from before and after the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1310 separate. If you are not interested, you can pass NULL.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1311
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1312 png_read_end(png_ptr, end_info);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1313
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1314 When you are done, you can free all memory allocated by libpng like this:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1315
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1316 png_destroy_read_struct(&png_ptr, &info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1317 &end_info);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1318
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1319 It is also possible to individually free the info_ptr members that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1320 point to libpng-allocated storage with the following function:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1321
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1322 png_free_data(png_ptr, info_ptr, mask, seq)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1323 mask - identifies data to be freed, a mask
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1324 containing the bitwise OR of one or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1325 more of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1326 PNG_FREE_PLTE, PNG_FREE_TRNS,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1327 PNG_FREE_HIST, PNG_FREE_ICCP,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1328 PNG_FREE_PCAL, PNG_FREE_ROWS,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1329 PNG_FREE_SCAL, PNG_FREE_SPLT,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1330 PNG_FREE_TEXT, PNG_FREE_UNKN,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1331 or simply PNG_FREE_ALL
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1332 seq - sequence number of item to be freed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1333 (-1 for all items)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1334
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1335 This function may be safely called when the relevant storage has
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1336 already been freed, or has not yet been allocated, or was allocated
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1337 by the user and not by libpng, and will in those
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1338 cases do nothing. The "seq" parameter is ignored if only one item
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1339 of the selected data type, such as PLTE, is allowed. If "seq" is not
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1340 -1, and multiple items are allowed for the data type identified in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1341 the mask, such as text or sPLT, only the n'th item in the structure
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1342 is freed, where n is "seq".
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1343
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1344 The default behavior is only to free data that was allocated internally
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1345 by libpng. This can be changed, so that libpng will not free the data,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1346 or so that it will free data that was allocated by the user with png_malloc()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1347 or png_zalloc() and passed in via a png_set_*() function, with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1348
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1349 png_data_freer(png_ptr, info_ptr, freer, mask)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1350 mask - which data elements are affected
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1351 same choices as in png_free_data()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1352 freer - one of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1353 PNG_DESTROY_WILL_FREE_DATA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1354 PNG_SET_WILL_FREE_DATA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1355 PNG_USER_WILL_FREE_DATA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1356
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1357 This function only affects data that has already been allocated.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1358 You can call this function after reading the PNG data but before calling
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1359 any png_set_*() functions, to control whether the user or the png_set_*()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1360 function is responsible for freeing any existing data that might be present,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1361 and again after the png_set_*() functions to control whether the user
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1362 or png_destroy_*() is supposed to free the data. When the user assumes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1363 responsibility for libpng-allocated data, the application must use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1364 png_free() to free it, and when the user transfers responsibility to libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1365 for data that the user has allocated, the user must have used png_malloc()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1366 or png_zalloc() to allocate it.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1367
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1368 If you allocated your row_pointers in a single block, as suggested above in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1369 the description of the high level read interface, you must not transfer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1370 responsibility for freeing it to the png_set_rows or png_read_destroy function,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1371 because they would also try to free the individual row_pointers[i].
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1372
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1373 If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1374 separately, do not transfer responsibility for freeing text_ptr to libpng,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1375 because when libpng fills a png_text structure it combines these members with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1376 the key member, and png_free_data() will free only text_ptr.key. Similarly,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1377 if you transfer responsibility for free'ing text_ptr from libpng to your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1378 application, your application must not separately free those members.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1379
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1380 The png_free_data() function will turn off the "valid" flag for anything
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1381 it frees. If you need to turn the flag off for a chunk that was freed by your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1382 application instead of by libpng, you can use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1383
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1384 png_set_invalid(png_ptr, info_ptr, mask);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1385 mask - identifies the chunks to be made invalid,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1386 containing the bitwise OR of one or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1387 more of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1388 PNG_INFO_gAMA, PNG_INFO_sBIT,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1389 PNG_INFO_cHRM, PNG_INFO_PLTE,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1390 PNG_INFO_tRNS, PNG_INFO_bKGD,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1391 PNG_INFO_hIST, PNG_INFO_pHYs,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1392 PNG_INFO_oFFs, PNG_INFO_tIME,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1393 PNG_INFO_pCAL, PNG_INFO_sRGB,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1394 PNG_INFO_iCCP, PNG_INFO_sPLT,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1395 PNG_INFO_sCAL, PNG_INFO_IDAT
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1396
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1397 For a more compact example of reading a PNG image, see the file example.c.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1398
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1399 Reading PNG files progressively
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1400
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1401 The progressive reader is slightly different then the non-progressive
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1402 reader. Instead of calling png_read_info(), png_read_rows(), and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1403 png_read_end(), you make one call to png_process_data(), which calls
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1404 callbacks when it has the info, a row, or the end of the image. You
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1405 set up these callbacks with png_set_progressive_read_fn(). You don't
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1406 have to worry about the input/output functions of libpng, as you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1407 giving the library the data directly in png_process_data(). I will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1408 assume that you have read the section on reading PNG files above,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1409 so I will only highlight the differences (although I will show
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1410 all of the code).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1411
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1412 png_structp png_ptr;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1413 png_infop info_ptr;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1414
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1415 /* An example code fragment of how you would
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1416 initialize the progressive reader in your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1417 application. */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1418 int
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1419 initialize_png_reader()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1420 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1421 png_ptr = png_create_read_struct
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1422 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1423 user_error_fn, user_warning_fn);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1424 if (!png_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1425 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1426 info_ptr = png_create_info_struct(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1427 if (!info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1428 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1429 png_destroy_read_struct(&png_ptr, (png_infopp)NULL,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1430 (png_infopp)NULL);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1431 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1432 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1433
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1434 if (setjmp(png_jmpbuf(png_ptr)))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1435 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1436 png_destroy_read_struct(&png_ptr, &info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1437 (png_infopp)NULL);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1438 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1439 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1440
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1441 /* This one's new. You can provide functions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1442 to be called when the header info is valid,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1443 when each row is completed, and when the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1444 is finished. If you aren't using all functions,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1445 you can specify NULL parameters. Even when all
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1446 three functions are NULL, you need to call
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1447 png_set_progressive_read_fn(). You can use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1448 any struct as the user_ptr (cast to a void pointer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1449 for the function call), and retrieve the pointer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1450 from inside the callbacks using the function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1451
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1452 png_get_progressive_ptr(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1453
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1454 which will return a void pointer, which you have
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1455 to cast appropriately.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1456 */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1457 png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1458 info_callback, row_callback, end_callback);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1459
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1460 return 0;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1461 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1462
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1463 /* A code fragment that you call as you receive blocks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1464 of data */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1465 int
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1466 process_data(png_bytep buffer, png_uint_32 length)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1467 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1468 if (setjmp(png_jmpbuf(png_ptr)))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1469 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1470 png_destroy_read_struct(&png_ptr, &info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1471 (png_infopp)NULL);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1472 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1473 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1474
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1475 /* This one's new also. Simply give it a chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1476 of data from the file stream (in order, of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1477 course). On machines with segmented memory
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1478 models machines, don't give it any more than
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1479 64K. The library seems to run fine with sizes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1480 of 4K. Although you can give it much less if
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1481 necessary (I assume you can give it chunks of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1482 1 byte, I haven't tried less then 256 bytes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1483 yet). When this function returns, you may
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1484 want to display any rows that were generated
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1485 in the row callback if you don't already do
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1486 so there.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1487 */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1488 png_process_data(png_ptr, info_ptr, buffer, length);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1489 return 0;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1490 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1491
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1492 /* This function is called (as set by
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1493 png_set_progressive_read_fn() above) when enough data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1494 has been supplied so all of the header has been
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1495 read.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1496 */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1497 void
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1498 info_callback(png_structp png_ptr, png_infop info)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1499 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1500 /* Do any setup here, including setting any of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1501 the transformations mentioned in the Reading
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1502 PNG files section. For now, you _must_ call
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1503 either png_start_read_image() or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1504 png_read_update_info() after all the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1505 transformations are set (even if you don't set
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1506 any). You may start getting rows before
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1507 png_process_data() returns, so this is your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1508 last chance to prepare for that.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1509 */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1510 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1511
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1512 /* This function is called when each row of image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1513 data is complete */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1514 void
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1515 row_callback(png_structp png_ptr, png_bytep new_row,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1516 png_uint_32 row_num, int pass)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1517 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1518 /* If the image is interlaced, and you turned
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1519 on the interlace handler, this function will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1520 be called for every row in every pass. Some
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1521 of these rows will not be changed from the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1522 previous pass. When the row is not changed,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1523 the new_row variable will be NULL. The rows
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1524 and passes are called in order, so you don't
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1525 really need the row_num and pass, but I'm
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1526 supplying them because it may make your life
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1527 easier.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1528
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1529 For the non-NULL rows of interlaced images,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1530 you must call png_progressive_combine_row()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1531 passing in the row and the old row. You can
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1532 call this function for NULL rows (it will just
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1533 return) and for non-interlaced images (it just
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1534 does the memcpy for you) if it will make the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1535 code easier. Thus, you can just do this for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1536 all cases:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1537 */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1538
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1539 png_progressive_combine_row(png_ptr, old_row,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1540 new_row);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1541
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1542 /* where old_row is what was displayed for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1543 previously for the row. Note that the first
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1544 pass (pass == 0, really) will completely cover
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1545 the old row, so the rows do not have to be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1546 initialized. After the first pass (and only
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1547 for interlaced images), you will have to pass
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1548 the current row, and the function will combine
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1549 the old row and the new row.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1550 */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1551 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1552
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1553 void
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1554 end_callback(png_structp png_ptr, png_infop info)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1555 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1556 /* This function is called after the whole image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1557 has been read, including any chunks after the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1558 image (up to and including the IEND). You
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1559 will usually have the same info chunk as you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1560 had in the header, although some data may have
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1561 been added to the comments and time fields.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1562
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1563 Most people won't do much here, perhaps setting
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1564 a flag that marks the image as finished.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1565 */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1566 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1567
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1568
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1569
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1570 IV. Writing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1571
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1572 Much of this is very similar to reading. However, everything of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1573 importance is repeated here, so you won't have to constantly look
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1574 back up in the reading section to understand writing.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1575
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1576 Setup
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1577
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1578 You will want to do the I/O initialization before you get into libpng,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1579 so if it doesn't work, you don't have anything to undo. If you are not
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1580 using the standard I/O functions, you will need to replace them with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1581 custom writing functions. See the discussion under Customizing libpng.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1582
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1583 FILE *fp = fopen(file_name, "wb");
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1584 if (!fp)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1585 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1586 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1587 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1588
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1589 Next, png_struct and png_info need to be allocated and initialized.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1590 As these can be both relatively large, you may not want to store these
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1591 on the stack, unless you have stack space to spare. Of course, you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1592 will want to check if they return NULL. If you are also reading,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1593 you won't want to name your read structure and your write structure
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1594 both "png_ptr"; you can call them anything you like, such as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1595 "read_ptr" and "write_ptr". Look at pngtest.c, for example.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1596
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1597 png_structp png_ptr = png_create_write_struct
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1598 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1599 user_error_fn, user_warning_fn);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1600 if (!png_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1601 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1602
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1603 png_infop info_ptr = png_create_info_struct(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1604 if (!info_ptr)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1605 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1606 png_destroy_write_struct(&png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1607 (png_infopp)NULL);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1608 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1609 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1610
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1611 If you want to use your own memory allocation routines,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1612 define PNG_USER_MEM_SUPPORTED and use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1613 png_create_write_struct_2() instead of png_create_write_struct():
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1614
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1615 png_structp png_ptr = png_create_write_struct_2
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1616 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1617 user_error_fn, user_warning_fn, (png_voidp)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1618 user_mem_ptr, user_malloc_fn, user_free_fn);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1619
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1620 After you have these structures, you will need to set up the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1621 error handling. When libpng encounters an error, it expects to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1622 longjmp() back to your routine. Therefore, you will need to call
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1623 setjmp() and pass the png_jmpbuf(png_ptr). If you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1624 write the file from different routines, you will need to update
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1625 the png_jmpbuf(png_ptr) every time you enter a new routine that will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1626 call a png_*() function. See your documentation of setjmp/longjmp
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1627 for your compiler for more information on setjmp/longjmp. See
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1628 the discussion on libpng error handling in the Customizing Libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1629 section below for more information on the libpng error handling.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1630
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1631 if (setjmp(png_jmpbuf(png_ptr)))
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1632 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1633 png_destroy_write_struct(&png_ptr, &info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1634 fclose(fp);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1635 return (ERROR);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1636 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1637 ...
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1638 return;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1639
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1640 If you would rather avoid the complexity of setjmp/longjmp issues,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1641 you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1642 errors will result in a call to PNG_ABORT() which defaults to abort().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1643
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1644 Now you need to set up the output code. The default for libpng is to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1645 use the C function fwrite(). If you use this, you will need to pass a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1646 valid FILE * in the function png_init_io(). Be sure that the file is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1647 opened in binary mode. Again, if you wish to handle writing data in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1648 another way, see the discussion on libpng I/O handling in the Customizing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1649 Libpng section below.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1650
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1651 png_init_io(png_ptr, fp);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1652
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1653 If you are embedding your PNG into a datastream such as MNG, and don't
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1654 want libpng to write the 8-byte signature, or if you have already
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1655 written the signature in your application, use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1656
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1657 png_set_sig_bytes(png_ptr, 8);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1658
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1659 to inform libpng that it should not write a signature.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1660
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1661 Write callbacks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1662
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1663 At this point, you can set up a callback function that will be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1664 called after each row has been written, which you can use to control
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1665 a progress meter or the like. It's demonstrated in pngtest.c.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1666 You must supply a function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1667
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1668 void write_row_callback(png_ptr, png_uint_32 row,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1669 int pass);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1670 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1671 /* put your code here */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1672 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1673
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1674 (You can give it another name that you like instead of "write_row_callback")
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1675
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1676 To inform libpng about your function, use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1677
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1678 png_set_write_status_fn(png_ptr, write_row_callback);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1679
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1680 You now have the option of modifying how the compression library will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1681 run. The following functions are mainly for testing, but may be useful
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1682 in some cases, like if you need to write PNG files extremely fast and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1683 are willing to give up some compression, or if you want to get the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1684 maximum possible compression at the expense of slower writing. If you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1685 have no special needs in this area, let the library do what it wants by
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1686 not calling this function at all, as it has been tuned to deliver a good
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1687 speed/compression ratio. The second parameter to png_set_filter() is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1688 the filter method, for which the only valid values are 0 (as of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1689 July 1999 PNG specification, version 1.2) or 64 (if you are writing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1690 a PNG datastream that is to be embedded in a MNG datastream). The third
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1691 parameter is a flag that indicates which filter type(s) are to be tested
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1692 for each scanline. See the PNG specification for details on the specific filter
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1693 types.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1694
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1695
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1696 /* turn on or off filtering, and/or choose
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1697 specific filters. You can use either a single
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1698 PNG_FILTER_VALUE_NAME or the bitwise OR of one
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1699 or more PNG_FILTER_NAME masks. */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1700 png_set_filter(png_ptr, 0,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1701 PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1702 PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1703 PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1704 PNG_FILTER_AVE | PNG_FILTER_VALUE_AVE |
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1705 PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1706 PNG_ALL_FILTERS);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1707
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1708 If an application
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1709 wants to start and stop using particular filters during compression,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1710 it should start out with all of the filters (to ensure that the previous
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1711 row of pixels will be stored in case it's needed later), and then add
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1712 and remove them after the start of compression.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1713
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1714 If you are writing a PNG datastream that is to be embedded in a MNG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1715 datastream, the second parameter can be either 0 or 64.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1716
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1717 The png_set_compression_*() functions interface to the zlib compression
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1718 library, and should mostly be ignored unless you really know what you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1719 doing. The only generally useful call is png_set_compression_level()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1720 which changes how much time zlib spends on trying to compress the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1721 data. See the Compression Library (zlib.h and algorithm.txt, distributed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1722 with zlib) for details on the compression levels.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1723
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1724 /* set the zlib compression level */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1725 png_set_compression_level(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1726 Z_BEST_COMPRESSION);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1727
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1728 /* set other zlib parameters */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1729 png_set_compression_mem_level(png_ptr, 8);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1730 png_set_compression_strategy(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1731 Z_DEFAULT_STRATEGY);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1732 png_set_compression_window_bits(png_ptr, 15);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1733 png_set_compression_method(png_ptr, 8);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1734 png_set_compression_buffer_size(png_ptr, 8192)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1735
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1736 extern PNG_EXPORT(void,png_set_zbuf_size)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1737
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1738 Setting the contents of info for output
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1739
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1740 You now need to fill in the png_info structure with all the data you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1741 wish to write before the actual image. Note that the only thing you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1742 are allowed to write after the image is the text chunks and the time
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1743 chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1744 the latest PNG specification for more information on that. If you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1745 wish to write them before the image, fill them in now, and flag that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1746 data as being valid. If you want to wait until after the data, don't
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1747 fill them until png_write_end(). For all the fields in png_info and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1748 their data types, see png.h. For explanations of what the fields
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1749 contain, see the PNG specification.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1750
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1751 Some of the more important parts of the png_info are:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1752
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1753 png_set_IHDR(png_ptr, info_ptr, width, height,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1754 bit_depth, color_type, interlace_type,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1755 compression_type, filter_method)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1756 width - holds the width of the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1757 in pixels (up to 2^31).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1758 height - holds the height of the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1759 in pixels (up to 2^31).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1760 bit_depth - holds the bit depth of one of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1761 image channels.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1762 (valid values are 1, 2, 4, 8, 16
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1763 and depend also on the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1764 color_type. See also significant
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1765 bits (sBIT) below).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1766 color_type - describes which color/alpha
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1767 channels are present.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1768 PNG_COLOR_TYPE_GRAY
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1769 (bit depths 1, 2, 4, 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1770 PNG_COLOR_TYPE_GRAY_ALPHA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1771 (bit depths 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1772 PNG_COLOR_TYPE_PALETTE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1773 (bit depths 1, 2, 4, 8)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1774 PNG_COLOR_TYPE_RGB
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1775 (bit_depths 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1776 PNG_COLOR_TYPE_RGB_ALPHA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1777 (bit_depths 8, 16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1778
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1779 PNG_COLOR_MASK_PALETTE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1780 PNG_COLOR_MASK_COLOR
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1781 PNG_COLOR_MASK_ALPHA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1782
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1783 interlace_type - PNG_INTERLACE_NONE or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1784 PNG_INTERLACE_ADAM7
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1785 compression_type - (must be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1786 PNG_COMPRESSION_TYPE_DEFAULT)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1787 filter_method - (must be PNG_FILTER_TYPE_DEFAULT
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1788 or, if you are writing a PNG to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1789 be embedded in a MNG datastream,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1790 can also be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1791 PNG_INTRAPIXEL_DIFFERENCING)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1792
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1793 If you call png_set_IHDR(), the call must appear before any of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1794 other png_set_*() functions, which might require access to some of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1795 the IHDR settings. The remaining png_set_*() functions can be called
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1796 in any order.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1797
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1798 png_set_PLTE(png_ptr, info_ptr, palette,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1799 num_palette);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1800 palette - the palette for the file
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1801 (array of png_color)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1802 num_palette - number of entries in the palette
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1803
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1804 png_set_gAMA(png_ptr, info_ptr, gamma);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1805 gamma - the gamma the image was created
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1806 at (PNG_INFO_gAMA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1807
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1808 png_set_sRGB(png_ptr, info_ptr, srgb_intent);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1809 srgb_intent - the rendering intent
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1810 (PNG_INFO_sRGB) The presence of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1811 the sRGB chunk means that the pixel
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1812 data is in the sRGB color space.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1813 This chunk also implies specific
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1814 values of gAMA and cHRM. Rendering
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1815 intent is the CSS-1 property that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1816 has been defined by the International
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1817 Color Consortium
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1818 (http://www.color.org).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1819 It can be one of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1820 PNG_sRGB_INTENT_SATURATION,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1821 PNG_sRGB_INTENT_PERCEPTUAL,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1822 PNG_sRGB_INTENT_ABSOLUTE, or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1823 PNG_sRGB_INTENT_RELATIVE.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1824
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1825
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1826 png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1827 srgb_intent);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1828 srgb_intent - the rendering intent
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1829 (PNG_INFO_sRGB) The presence of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1830 sRGB chunk means that the pixel
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1831 data is in the sRGB color space.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1832 This function also causes gAMA and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1833 cHRM chunks with the specific values
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1834 that are consistent with sRGB to be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1835 written.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1836
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1837 png_set_iCCP(png_ptr, info_ptr, name, compression_type,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1838 profile, proflen);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1839 name - The profile name.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1840 compression - The compression type; always
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1841 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1842 You may give NULL to this argument to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1843 ignore it.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1844 profile - International Color Consortium color
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1845 profile data. May contain NULs.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1846 proflen - length of profile data in bytes.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1847
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1848 png_set_sBIT(png_ptr, info_ptr, sig_bit);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1849 sig_bit - the number of significant bits for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1850 (PNG_INFO_sBIT) each of the gray, red,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1851 green, and blue channels, whichever are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1852 appropriate for the given color type
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1853 (png_color_16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1854
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1855 png_set_tRNS(png_ptr, info_ptr, trans, num_trans,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1856 trans_values);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1857 trans - array of transparent entries for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1858 palette (PNG_INFO_tRNS)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1859 trans_values - graylevel or color sample values of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1860 the single transparent color for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1861 non-paletted images (PNG_INFO_tRNS)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1862 num_trans - number of transparent entries
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1863 (PNG_INFO_tRNS)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1864
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1865 png_set_hIST(png_ptr, info_ptr, hist);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1866 (PNG_INFO_hIST)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1867 hist - histogram of palette (array of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1868 png_uint_16)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1869
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1870 png_set_tIME(png_ptr, info_ptr, mod_time);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1871 mod_time - time image was last modified
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1872 (PNG_VALID_tIME)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1873
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1874 png_set_bKGD(png_ptr, info_ptr, background);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1875 background - background color (PNG_VALID_bKGD)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1876
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1877 png_set_text(png_ptr, info_ptr, text_ptr, num_text);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1878 text_ptr - array of png_text holding image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1879 comments
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1880 text_ptr[i].compression - type of compression used
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1881 on "text" PNG_TEXT_COMPRESSION_NONE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1882 PNG_TEXT_COMPRESSION_zTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1883 PNG_ITXT_COMPRESSION_NONE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1884 PNG_ITXT_COMPRESSION_zTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1885 text_ptr[i].key - keyword for comment. Must contain
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1886 1-79 characters.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1887 text_ptr[i].text - text comments for current
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1888 keyword. Can be NULL or empty.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1889 text_ptr[i].text_length - length of text string,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1890 after decompression, 0 for iTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1891 text_ptr[i].itxt_length - length of itxt string,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1892 after decompression, 0 for tEXt/zTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1893 text_ptr[i].lang - language of comment (NULL or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1894 empty for unknown).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1895 text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1896 or empty for unknown).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1897 num_text - number of comments
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1898
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1899 png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1900 num_spalettes);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1901 palette_ptr - array of png_sPLT_struct structures
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1902 to be added to the list of palettes
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1903 in the info structure.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1904 num_spalettes - number of palette structures to be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1905 added.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1906
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1907 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1908 unit_type);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1909 offset_x - positive offset from the left
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1910 edge of the screen
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1911 offset_y - positive offset from the top
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1912 edge of the screen
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1913 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1914
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1915 png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1916 unit_type);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1917 res_x - pixels/unit physical resolution
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1918 in x direction
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1919 res_y - pixels/unit physical resolution
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1920 in y direction
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1921 unit_type - PNG_RESOLUTION_UNKNOWN,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1922 PNG_RESOLUTION_METER
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1923
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1924 png_set_sCAL(png_ptr, info_ptr, unit, width, height)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1925 unit - physical scale units (an integer)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1926 width - width of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1927 height - height of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1928 (width and height are doubles)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1929
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1930 png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1931 unit - physical scale units (an integer)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1932 width - width of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1933 height - height of a pixel in physical scale units
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1934 (width and height are strings like "2.54")
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1935
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1936 png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1937 num_unknowns)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1938 unknowns - array of png_unknown_chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1939 structures holding unknown chunks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1940 unknowns[i].name - name of unknown chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1941 unknowns[i].data - data of unknown chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1942 unknowns[i].size - size of unknown chunk's data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1943 unknowns[i].location - position to write chunk in file
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1944 0: do not write chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1945 PNG_HAVE_IHDR: before PLTE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1946 PNG_HAVE_PLTE: before IDAT
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1947 PNG_AFTER_IDAT: after IDAT
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1948
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1949 The "location" member is set automatically according to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1950 what part of the output file has already been written.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1951 You can change its value after calling png_set_unknown_chunks()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1952 as demonstrated in pngtest.c. Within each of the "locations",
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1953 the chunks are sequenced according to their position in the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1954 structure (that is, the value of "i", which is the order in which
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1955 the chunk was either read from the input file or defined with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1956 png_set_unknown_chunks).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1957
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1958 A quick word about text and num_text. text is an array of png_text
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1959 structures. num_text is the number of valid structures in the array.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1960 Each png_text structure holds a language code, a keyword, a text value,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1961 and a compression type.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1962
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1963 The compression types have the same valid numbers as the compression
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1964 types of the image data. Currently, the only valid number is zero.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1965 However, you can store text either compressed or uncompressed, unlike
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1966 images, which always have to be compressed. So if you don't want the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1967 text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1968 Because tEXt and zTXt chunks don't have a language field, if you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1969 specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1970 any language code or translated keyword will not be written out.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1971
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1972 Until text gets around 1000 bytes, it is not worth compressing it.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1973 After the text has been written out to the file, the compression type
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1974 is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1975 so that it isn't written out again at the end (in case you are calling
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1976 png_write_end() with the same struct.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1977
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1978 The keywords that are given in the PNG Specification are:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1979
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1980 Title Short (one line) title or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1981 caption for image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1982 Author Name of image's creator
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1983 Description Description of image (possibly long)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1984 Copyright Copyright notice
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1985 Creation Time Time of original image creation
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1986 (usually RFC 1123 format, see below)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1987 Software Software used to create the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1988 Disclaimer Legal disclaimer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1989 Warning Warning of nature of content
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1990 Source Device used to create the image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1991 Comment Miscellaneous comment; conversion
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1992 from other image format
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1993
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1994 The keyword-text pairs work like this. Keywords should be short
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1995 simple descriptions of what the comment is about. Some typical
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1996 keywords are found in the PNG specification, as is some recommendations
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1997 on keywords. You can repeat keywords in a file. You can even write
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1998 some text before the image and some after. For example, you may want
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
1999 to put a description of the image before the image, but leave the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2000 disclaimer until after, so viewers working over modem connections
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2001 don't have to wait for the disclaimer to go over the modem before
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2002 they start seeing the image. Finally, keywords should be full
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2003 words, not abbreviations. Keywords and text are in the ISO 8859-1
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2004 (Latin-1) character set (a superset of regular ASCII) and can not
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2005 contain NUL characters, and should not contain control or other
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2006 unprintable characters. To make the comments widely readable, stick
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2007 with basic ASCII, and avoid machine specific character set extensions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2008 like the IBM-PC character set. The keyword must be present, but
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2009 you can leave off the text string on non-compressed pairs.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2010 Compressed pairs must have a text string, as only the text string
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2011 is compressed anyway, so the compression would be meaningless.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2012
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2013 PNG supports modification time via the png_time structure. Two
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2014 conversion routines are provided, png_convert_from_time_t() for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2015 time_t and png_convert_from_struct_tm() for struct tm. The
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2016 time_t routine uses gmtime(). You don't have to use either of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2017 these, but if you wish to fill in the png_time structure directly,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2018 you should provide the time in universal time (GMT) if possible
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2019 instead of your local time. Note that the year number is the full
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2020 year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2021 that months start with 1.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2022
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2023 If you want to store the time of the original image creation, you should
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2024 use a plain tEXt chunk with the "Creation Time" keyword. This is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2025 necessary because the "creation time" of a PNG image is somewhat vague,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2026 depending on whether you mean the PNG file, the time the image was
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2027 created in a non-PNG format, a still photo from which the image was
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2028 scanned, or possibly the subject matter itself. In order to facilitate
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2029 machine-readable dates, it is recommended that the "Creation Time"
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2030 tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2031 although this isn't a requirement. Unlike the tIME chunk, the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2032 "Creation Time" tEXt chunk is not expected to be automatically changed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2033 by the software. To facilitate the use of RFC 1123 dates, a function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2034 png_convert_to_rfc1123(png_timep) is provided to convert from PNG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2035 time to an RFC 1123 format string.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2036
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2037 Writing unknown chunks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2038
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2039 You can use the png_set_unknown_chunks function to queue up chunks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2040 for writing. You give it a chunk name, raw data, and a size; that's
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2041 all there is to it. The chunks will be written by the next following
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2042 png_write_info_before_PLTE, png_write_info, or png_write_end function.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2043 Any chunks previously read into the info structure's unknown-chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2044 list will also be written out in a sequence that satisfies the PNG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2045 specification's ordering rules.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2046
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2047 The high-level write interface
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2048
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2049 At this point there are two ways to proceed; through the high-level
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2050 write interface, or through a sequence of low-level write operations.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2051 You can use the high-level interface if your image data is present
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2052 in the info structure. All defined output
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2053 transformations are permitted, enabled by the following masks.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2054
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2055 PNG_TRANSFORM_IDENTITY No transformation
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2056 PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2057 PNG_TRANSFORM_PACKSWAP Change order of packed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2058 pixels to LSB first
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2059 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2060 PNG_TRANSFORM_SHIFT Normalize pixels to the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2061 sBIT depth
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2062 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2063 to BGRA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2064 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2065 to AG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2066 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2067 to transparency
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2068 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2069 PNG_TRANSFORM_STRIP_FILLER Strip out filler bytes.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2070
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2071 If you have valid image data in the info structure (you can use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2072 png_set_rows() to put image data in the info structure), simply do this:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2073
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2074 png_write_png(png_ptr, info_ptr, png_transforms, NULL)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2075
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2076 where png_transforms is an integer containing the bitwise OR of some set of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2077 transformation flags. This call is equivalent to png_write_info(),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2078 followed the set of transformations indicated by the transform mask,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2079 then png_write_image(), and finally png_write_end().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2080
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2081 (The final parameter of this call is not yet used. Someday it might point
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2082 to transformation parameters required by some future output transform.)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2083
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2084 You must use png_transforms and not call any png_set_transform() functions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2085 when you use png_write_png().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2086
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2087 The low-level write interface
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2088
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2089 If you are going the low-level route instead, you are now ready to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2090 write all the file information up to the actual image data. You do
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2091 this with a call to png_write_info().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2092
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2093 png_write_info(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2094
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2095 Note that there is one transformation you may need to do before
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2096 png_write_info(). In PNG files, the alpha channel in an image is the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2097 level of opacity. If your data is supplied as a level of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2098 transparency, you can invert the alpha channel before you write it, so
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2099 that 0 is fully transparent and 255 (in 8-bit or paletted images) or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2100 65535 (in 16-bit images) is fully opaque, with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2101
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2102 png_set_invert_alpha(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2103
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2104 This must appear before png_write_info() instead of later with the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2105 other transformations because in the case of paletted images the tRNS
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2106 chunk data has to be inverted before the tRNS chunk is written. If
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2107 your image is not a paletted image, the tRNS data (which in such cases
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2108 represents a single color to be rendered as transparent) won't need to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2109 be changed, and you can safely do this transformation after your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2110 png_write_info() call.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2111
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2112 If you need to write a private chunk that you want to appear before
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2113 the PLTE chunk when PLTE is present, you can write the PNG info in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2114 two steps, and insert code to write your own chunk between them:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2115
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2116 png_write_info_before_PLTE(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2117 png_set_unknown_chunks(png_ptr, info_ptr, ...);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2118 png_write_info(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2119
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2120 After you've written the file information, you can set up the library
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2121 to handle any special transformations of the image data. The various
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2122 ways to transform the data will be described in the order that they
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2123 should occur. This is important, as some of these change the color
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2124 type and/or bit depth of the data, and some others only work on
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2125 certain color types and bit depths. Even though each transformation
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2126 checks to see if it has data that it can do something with, you should
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2127 make sure to only enable a transformation if it will be valid for the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2128 data. For example, don't swap red and blue on grayscale data.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2129
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2130 PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2131 the library to strip input data that has 4 or 8 bytes per pixel down
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2132 to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2133 bytes per pixel).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2134
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2135 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2136
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2137 where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2138 PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2139 is stored XRGB or RGBX.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2140
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2141 PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2142 they can, resulting in, for example, 8 pixels per byte for 1 bit files.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2143 If the data is supplied at 1 pixel per byte, use this code, which will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2144 correctly pack the pixels into a single byte:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2145
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2146 png_set_packing(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2147
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2148 PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2149 data is of another bit depth, you can write an sBIT chunk into the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2150 file so that decoders can recover the original data if desired.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2151
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2152 /* Set the true bit depth of the image data */
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2153 if (color_type & PNG_COLOR_MASK_COLOR)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2154 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2155 sig_bit.red = true_bit_depth;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2156 sig_bit.green = true_bit_depth;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2157 sig_bit.blue = true_bit_depth;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2158 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2159 else
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2160 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2161 sig_bit.gray = true_bit_depth;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2162 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2163 if (color_type & PNG_COLOR_MASK_ALPHA)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2164 {
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2165 sig_bit.alpha = true_bit_depth;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2166 }
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2167
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2168 png_set_sBIT(png_ptr, info_ptr, &sig_bit);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2169
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2170 If the data is stored in the row buffer in a bit depth other than
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2171 one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2172 this will scale the values to appear to be the correct bit depth as
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2173 is required by PNG.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2174
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2175 png_set_shift(png_ptr, &sig_bit);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2176
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2177 PNG files store 16 bit pixels in network byte order (big-endian,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2178 ie. most significant bits first). This code would be used if they are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2179 supplied the other way (little-endian, i.e. least significant bits
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2180 first, the way PCs store them):
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2181
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2182 if (bit_depth > 8)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2183 png_set_swap(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2184
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2185 If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2186 need to change the order the pixels are packed into bytes, you can use:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2187
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2188 if (bit_depth < 8)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2189 png_set_packswap(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2190
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2191 PNG files store 3 color pixels in red, green, blue order. This code
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2192 would be used if they are supplied as blue, green, red:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2193
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2194 png_set_bgr(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2195
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2196 PNG files describe monochrome as black being zero and white being
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2197 one. This code would be used if the pixels are supplied with this reversed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2198 (black being one and white being zero):
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2199
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2200 png_set_invert_mono(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2201
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2202 Finally, you can write your own transformation function if none of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2203 the existing ones meets your needs. This is done by setting a callback
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2204 with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2205
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2206 png_set_write_user_transform_fn(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2207 write_transform_fn);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2208
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2209 You must supply the function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2210
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2211 void write_transform_fn(png_ptr ptr, row_info_ptr
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2212 row_info, png_bytep data)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2213
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2214 See pngtest.c for a working example. Your function will be called
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2215 before any of the other transformations are processed.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2216
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2217 You can also set up a pointer to a user structure for use by your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2218 callback function.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2219
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2220 png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2221
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2222 The user_channels and user_depth parameters of this function are ignored
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2223 when writing; you can set them to zero as shown.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2224
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2225 You can retrieve the pointer via the function png_get_user_transform_ptr().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2226 For example:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2227
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2228 voidp write_user_transform_ptr =
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2229 png_get_user_transform_ptr(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2230
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2231 It is possible to have libpng flush any pending output, either manually,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2232 or automatically after a certain number of lines have been written. To
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2233 flush the output stream a single time call:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2234
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2235 png_write_flush(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2236
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2237 and to have libpng flush the output stream periodically after a certain
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2238 number of scanlines have been written, call:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2239
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2240 png_set_flush(png_ptr, nrows);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2241
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2242 Note that the distance between rows is from the last time png_write_flush()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2243 was called, or the first row of the image if it has never been called.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2244 So if you write 50 lines, and then png_set_flush 25, it will flush the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2245 output on the next scanline, and every 25 lines thereafter, unless
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2246 png_write_flush() is called before 25 more lines have been written.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2247 If nrows is too small (less than about 10 lines for a 640 pixel wide
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2248 RGB image) the image compression may decrease noticeably (although this
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2249 may be acceptable for real-time applications). Infrequent flushing will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2250 only degrade the compression performance by a few percent over images
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2251 that do not use flushing.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2252
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2253 Writing the image data
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2254
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2255 That's it for the transformations. Now you can write the image data.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2256 The simplest way to do this is in one function call. If you have the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2257 whole image in memory, you can just call png_write_image() and libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2258 will write the image. You will need to pass in an array of pointers to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2259 each row. This function automatically handles interlacing, so you don't
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2260 need to call png_set_interlace_handling() or call this function multiple
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2261 times, or any of that other stuff necessary with png_write_rows().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2262
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2263 png_write_image(png_ptr, row_pointers);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2264
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2265 where row_pointers is:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2266
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2267 png_byte *row_pointers[height];
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2268
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2269 You can point to void or char or whatever you use for pixels.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2270
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2271 If you don't want to write the whole image at once, you can
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2272 use png_write_rows() instead. If the file is not interlaced,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2273 this is simple:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2274
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2275 png_write_rows(png_ptr, row_pointers,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2276 number_of_rows);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2277
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2278 row_pointers is the same as in the png_write_image() call.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2279
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2280 If you are just writing one row at a time, you can do this with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2281 a single row_pointer instead of an array of row_pointers:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2282
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2283 png_bytep row_pointer = row;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2284
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2285 png_write_row(png_ptr, row_pointer);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2286
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2287 When the file is interlaced, things can get a good deal more
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2288 complicated. The only currently (as of the PNG Specification
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2289 version 1.2, dated July 1999) defined interlacing scheme for PNG files
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2290 is the "Adam7" interlace scheme, that breaks down an
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2291 image into seven smaller images of varying size. libpng will build
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2292 these images for you, or you can do them yourself. If you want to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2293 build them yourself, see the PNG specification for details of which
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2294 pixels to write when.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2295
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2296 If you don't want libpng to handle the interlacing details, just
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2297 use png_set_interlace_handling() and call png_write_rows() the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2298 correct number of times to write all seven sub-images.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2299
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2300 If you want libpng to build the sub-images, call this before you start
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2301 writing any rows:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2302
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2303 number_of_passes =
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2304 png_set_interlace_handling(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2305
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2306 This will return the number of passes needed. Currently, this
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2307 is seven, but may change if another interlace type is added.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2308
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2309 Then write the complete image number_of_passes times.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2310
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2311 png_write_rows(png_ptr, row_pointers,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2312 number_of_rows);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2313
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2314 As some of these rows are not used, and thus return immediately,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2315 you may want to read about interlacing in the PNG specification,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2316 and only update the rows that are actually used.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2317
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2318 Finishing a sequential write
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2319
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2320 After you are finished writing the image, you should finish writing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2321 the file. If you are interested in writing comments or time, you should
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2322 pass an appropriately filled png_info pointer. If you are not interested,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2323 you can pass NULL.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2324
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2325 png_write_end(png_ptr, info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2326
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2327 When you are done, you can free all memory used by libpng like this:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2328
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2329 png_destroy_write_struct(&png_ptr, &info_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2330
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2331 It is also possible to individually free the info_ptr members that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2332 point to libpng-allocated storage with the following function:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2333
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2334 png_free_data(png_ptr, info_ptr, mask, seq)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2335 mask - identifies data to be freed, a mask
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2336 containing the bitwise OR of one or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2337 more of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2338 PNG_FREE_PLTE, PNG_FREE_TRNS,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2339 PNG_FREE_HIST, PNG_FREE_ICCP,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2340 PNG_FREE_PCAL, PNG_FREE_ROWS,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2341 PNG_FREE_SCAL, PNG_FREE_SPLT,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2342 PNG_FREE_TEXT, PNG_FREE_UNKN,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2343 or simply PNG_FREE_ALL
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2344 seq - sequence number of item to be freed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2345 (-1 for all items)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2346
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2347 This function may be safely called when the relevant storage has
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2348 already been freed, or has not yet been allocated, or was allocated
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2349 by the user and not by libpng, and will in those
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2350 cases do nothing. The "seq" parameter is ignored if only one item
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2351 of the selected data type, such as PLTE, is allowed. If "seq" is not
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2352 -1, and multiple items are allowed for the data type identified in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2353 the mask, such as text or sPLT, only the n'th item in the structure
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2354 is freed, where n is "seq".
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2355
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2356 If you allocated data such as a palette that you passed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2357 in to libpng with png_set_*, you must not free it until just before the call to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2358 png_destroy_write_struct().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2359
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2360 The default behavior is only to free data that was allocated internally
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2361 by libpng. This can be changed, so that libpng will not free the data,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2362 or so that it will free data that was allocated by the user with png_malloc()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2363 or png_zalloc() and passed in via a png_set_*() function, with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2364
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2365 png_data_freer(png_ptr, info_ptr, freer, mask)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2366 mask - which data elements are affected
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2367 same choices as in png_free_data()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2368 freer - one of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2369 PNG_DESTROY_WILL_FREE_DATA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2370 PNG_SET_WILL_FREE_DATA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2371 PNG_USER_WILL_FREE_DATA
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2372
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2373 For example, to transfer responsibility for some data from a read structure
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2374 to a write structure, you could use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2375
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2376 png_data_freer(read_ptr, read_info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2377 PNG_USER_WILL_FREE_DATA,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2378 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2379 png_data_freer(write_ptr, write_info_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2380 PNG_DESTROY_WILL_FREE_DATA,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2381 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2382
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2383 thereby briefly reassigning responsibility for freeing to the user but
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2384 immediately afterwards reassigning it once more to the write_destroy
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2385 function. Having done this, it would then be safe to destroy the read
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2386 structure and continue to use the PLTE, tRNS, and hIST data in the write
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2387 structure.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2388
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2389 This function only affects data that has already been allocated.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2390 You can call this function before calling after the png_set_*() functions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2391 to control whether the user or png_destroy_*() is supposed to free the data.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2392 When the user assumes responsibility for libpng-allocated data, the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2393 application must use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2394 png_free() to free it, and when the user transfers responsibility to libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2395 for data that the user has allocated, the user must have used png_malloc()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2396 or png_zalloc() to allocate it.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2397
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2398 If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2399 separately, do not transfer responsibility for freeing text_ptr to libpng,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2400 because when libpng fills a png_text structure it combines these members with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2401 the key member, and png_free_data() will free only text_ptr.key. Similarly,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2402 if you transfer responsibility for free'ing text_ptr from libpng to your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2403 application, your application must not separately free those members.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2404 For a more compact example of writing a PNG image, see the file example.c.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2405
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2406 V. Modifying/Customizing libpng:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2407
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2408 There are two issues here. The first is changing how libpng does
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2409 standard things like memory allocation, input/output, and error handling.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2410 The second deals with more complicated things like adding new chunks,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2411 adding new transformations, and generally changing how libpng works.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2412 Both of those are compile-time issues; that is, they are generally
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2413 determined at the time the code is written, and there is rarely a need
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2414 to provide the user with a means of changing them.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2415
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2416 Memory allocation, input/output, and error handling
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2417
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2418 All of the memory allocation, input/output, and error handling in libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2419 goes through callbacks that are user-settable. The default routines are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2420 in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2421 these functions, call the appropriate png_set_*_fn() function.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2422
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2423 Memory allocation is done through the functions png_malloc()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2424 and png_free(). These currently just call the standard C functions. If
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2425 your pointers can't access more then 64K at a time, you will want to set
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2426 MAXSEG_64K in zlib.h. Since it is unlikely that the method of handling
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2427 memory allocation on a platform will change between applications, these
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2428 functions must be modified in the library at compile time. If you prefer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2429 to use a different method of allocating and freeing data, you can use
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2430 png_create_read_struct_2() or png_create_write_struct_2() to register
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2431 your own functions as described above.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2432 These functions also provide a void pointer that can be retrieved via
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2433
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2434 mem_ptr=png_get_mem_ptr(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2435
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2436 Your replacement memory functions must have prototypes as follows:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2437
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2438 png_voidp malloc_fn(png_structp png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2439 png_size_t size);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2440 void free_fn(png_structp png_ptr, png_voidp ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2441
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2442 Your malloc_fn() must return NULL in case of failure. The png_malloc()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2443 function will normally call png_error() if it receives a NULL from the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2444 system memory allocator or from your replacement malloc_fn().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2445
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2446 Your free_fn() will never be called with a NULL ptr, since libpng's
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2447 png_free() checks for NULL before calling free_fn().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2448
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2449 Input/Output in libpng is done through png_read() and png_write(),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2450 which currently just call fread() and fwrite(). The FILE * is stored in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2451 png_struct and is initialized via png_init_io(). If you wish to change
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2452 the method of I/O, the library supplies callbacks that you can set
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2453 through the function png_set_read_fn() and png_set_write_fn() at run
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2454 time, instead of calling the png_init_io() function. These functions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2455 also provide a void pointer that can be retrieved via the function
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2456 png_get_io_ptr(). For example:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2457
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2458 png_set_read_fn(png_structp read_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2459 voidp read_io_ptr, png_rw_ptr read_data_fn)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2460
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2461 png_set_write_fn(png_structp write_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2462 voidp write_io_ptr, png_rw_ptr write_data_fn,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2463 png_flush_ptr output_flush_fn);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2464
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2465 voidp read_io_ptr = png_get_io_ptr(read_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2466 voidp write_io_ptr = png_get_io_ptr(write_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2467
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2468 The replacement I/O functions must have prototypes as follows:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2469
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2470 void user_read_data(png_structp png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2471 png_bytep data, png_size_t length);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2472 void user_write_data(png_structp png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2473 png_bytep data, png_size_t length);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2474 void user_flush_data(png_structp png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2475
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2476 Supplying NULL for the read, write, or flush functions sets them back
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2477 to using the default C stream functions. It is an error to read from
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2478 a write stream, and vice versa.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2479
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2480 Error handling in libpng is done through png_error() and png_warning().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2481 Errors handled through png_error() are fatal, meaning that png_error()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2482 should never return to its caller. Currently, this is handled via
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2483 setjmp() and longjmp() (unless you have compiled libpng with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2484 PNG_SETJMP_NOT_SUPPORTED, in which case it is handled via PNG_ABORT()),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2485 but you could change this to do things like exit() if you should wish.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2486
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2487 On non-fatal errors, png_warning() is called
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2488 to print a warning message, and then control returns to the calling code.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2489 By default png_error() and png_warning() print a message on stderr via
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2490 fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2491 (because you don't want the messages) or PNG_NO_STDIO defined (because
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2492 fprintf() isn't available). If you wish to change the behavior of the error
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2493 functions, you will need to set up your own message callbacks. These
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2494 functions are normally supplied at the time that the png_struct is created.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2495 It is also possible to redirect errors and warnings to your own replacement
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2496 functions after png_create_*_struct() has been called by calling:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2497
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2498 png_set_error_fn(png_structp png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2499 png_voidp error_ptr, png_error_ptr error_fn,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2500 png_error_ptr warning_fn);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2501
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2502 png_voidp error_ptr = png_get_error_ptr(png_ptr);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2503
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2504 If NULL is supplied for either error_fn or warning_fn, then the libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2505 default function will be used, calling fprintf() and/or longjmp() if a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2506 problem is encountered. The replacement error functions should have
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2507 parameters as follows:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2508
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2509 void user_error_fn(png_structp png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2510 png_const_charp error_msg);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2511 void user_warning_fn(png_structp png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2512 png_const_charp warning_msg);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2513
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2514 The motivation behind using setjmp() and longjmp() is the C++ throw and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2515 catch exception handling methods. This makes the code much easier to write,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2516 as there is no need to check every return code of every function call.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2517 However, there are some uncertainties about the status of local variables
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2518 after a longjmp, so the user may want to be careful about doing anything after
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2519 setjmp returns non-zero besides returning itself. Consult your compiler
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2520 documentation for more details. For an alternative approach, you may wish
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2521 to use the "cexcept" facility (see http://cexcept.sourceforge.net).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2522
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2523 Custom chunks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2524
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2525 If you need to read or write custom chunks, you may need to get deeper
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2526 into the libpng code. The library now has mechanisms for storing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2527 and writing chunks of unknown type; you can even declare callbacks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2528 for custom chunks. However, this may not be good enough if the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2529 library code itself needs to know about interactions between your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2530 chunk and existing `intrinsic' chunks.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2531
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2532 If you need to write a new intrinsic chunk, first read the PNG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2533 specification. Acquire a first level of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2534 understanding of how it works. Pay particular attention to the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2535 sections that describe chunk names, and look at how other chunks were
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2536 designed, so you can do things similarly. Second, check out the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2537 sections of libpng that read and write chunks. Try to find a chunk
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2538 that is similar to yours and use it as a template. More details can
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2539 be found in the comments inside the code. It is best to handle unknown
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2540 chunks in a generic method, via callback functions, instead of by
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2541 modifying libpng functions.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2542
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2543 If you wish to write your own transformation for the data, look through
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2544 the part of the code that does the transformations, and check out some of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2545 the simpler ones to get an idea of how they work. Try to find a similar
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2546 transformation to the one you want to add and copy off of it. More details
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2547 can be found in the comments inside the code itself.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2548
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2549 Configuring for 16 bit platforms
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2550
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2551 You will want to look into zconf.h to tell zlib (and thus libpng) that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2552 it cannot allocate more then 64K at a time. Even if you can, the memory
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2553 won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2554
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2555 Configuring for DOS
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2556
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2557 For DOS users who only have access to the lower 640K, you will
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2558 have to limit zlib's memory usage via a png_set_compression_mem_level()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2559 call. See zlib.h or zconf.h in the zlib library for more information.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2560
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2561 Configuring for Medium Model
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2562
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2563 Libpng's support for medium model has been tested on most of the popular
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2564 compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2565 defined, and FAR gets defined to far in pngconf.h, and you should be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2566 all set. Everything in the library (except for zlib's structure) is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2567 expecting far data. You must use the typedefs with the p or pp on
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2568 the end for pointers (or at least look at them and be careful). Make
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2569 note that the rows of data are defined as png_bytepp, which is an
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2570 unsigned char far * far *.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2571
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2572 Configuring for gui/windowing platforms:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2573
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2574 You will need to write new error and warning functions that use the GUI
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2575 interface, as described previously, and set them to be the error and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2576 warning functions at the time that png_create_*_struct() is called,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2577 in order to have them available during the structure initialization.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2578 They can be changed later via png_set_error_fn(). On some compilers,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2579 you may also have to change the memory allocators (png_malloc, etc.).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2580
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2581 Configuring for compiler xxx:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2582
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2583 All includes for libpng are in pngconf.h. If you need to add/change/delete
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2584 an include, this is the place to do it. The includes that are not
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2585 needed outside libpng are protected by the PNG_INTERNAL definition,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2586 which is only defined for those routines inside libpng itself. The
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2587 files in libpng proper only include png.h, which includes pngconf.h.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2588
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2589 Configuring zlib:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2590
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2591 There are special functions to configure the compression. Perhaps the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2592 most useful one changes the compression level, which currently uses
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2593 input compression values in the range 0 - 9. The library normally
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2594 uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2595 have shown that for a large majority of images, compression values in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2596 the range 3-6 compress nearly as well as higher levels, and do so much
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2597 faster. For online applications it may be desirable to have maximum speed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2598 (Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2599 specify no compression (Z_NO_COMPRESSION = 0), but this would create
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2600 files larger than just storing the raw bitmap. You can specify the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2601 compression level by calling:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2602
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2603 png_set_compression_level(png_ptr, level);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2604
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2605 Another useful one is to reduce the memory level used by the library.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2606 The memory level defaults to 8, but it can be lowered if you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2607 short on memory (running DOS, for example, where you only have 640K).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2608 Note that the memory level does have an effect on compression; among
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2609 other things, lower levels will result in sections of incompressible
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2610 data being emitted in smaller stored blocks, with a correspondingly
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2611 larger relative overhead of up to 15% in the worst case.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2612
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2613 png_set_compression_mem_level(png_ptr, level);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2614
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2615 The other functions are for configuring zlib. They are not recommended
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2616 for normal use and may result in writing an invalid PNG file. See
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2617 zlib.h for more information on what these mean.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2618
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2619 png_set_compression_strategy(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2620 strategy);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2621 png_set_compression_window_bits(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2622 window_bits);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2623 png_set_compression_method(png_ptr, method);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2624 png_set_compression_buffer_size(png_ptr, size);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2625
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2626 Controlling row filtering
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2627
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2628 If you want to control whether libpng uses filtering or not, which
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2629 filters are used, and how it goes about picking row filters, you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2630 can call one of these functions. The selection and configuration
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2631 of row filters can have a significant impact on the size and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2632 encoding speed and a somewhat lesser impact on the decoding speed
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2633 of an image. Filtering is enabled by default for RGB and grayscale
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2634 images (with and without alpha), but not for paletted images nor
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2635 for any images with bit depths less than 8 bits/pixel.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2636
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2637 The 'method' parameter sets the main filtering method, which is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2638 currently only '0' in the PNG 1.2 specification. The 'filters'
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2639 parameter sets which filter(s), if any, should be used for each
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2640 scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2641 to turn filtering on and off, respectively.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2642
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2643 Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2644 PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2645 ORed together with '|' to specify one or more filters to use.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2646 These filters are described in more detail in the PNG specification.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2647 If you intend to change the filter type during the course of writing
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2648 the image, you should start with flags set for all of the filters
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2649 you intend to use so that libpng can initialize its internal
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2650 structures appropriately for all of the filter types. (Note that this
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2651 means the first row must always be adaptively filtered, because libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2652 currently does not allocate the filter buffers until png_write_row()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2653 is called for the first time.)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2654
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2655 filters = PNG_FILTER_NONE | PNG_FILTER_SUB
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2656 PNG_FILTER_UP | PNG_FILTER_AVE |
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2657 PNG_FILTER_PAETH | PNG_ALL_FILTERS;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2658
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2659 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2660 filters);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2661 The second parameter can also be
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2662 PNG_INTRAPIXEL_DIFFERENCING if you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2663 writing a PNG to be embedded in a MNG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2664 datastream. This parameter must be the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2665 same as the value of filter_method used
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2666 in png_set_IHDR().
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2667
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2668 It is also possible to influence how libpng chooses from among the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2669 available filters. This is done in one or both of two ways - by
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2670 telling it how important it is to keep the same filter for successive
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2671 rows, and by telling it the relative computational costs of the filters.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2672
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2673 double weights[3] = {1.5, 1.3, 1.1},
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2674 costs[PNG_FILTER_VALUE_LAST] =
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2675 {1.0, 1.3, 1.3, 1.5, 1.7};
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2676
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2677 png_set_filter_heuristics(png_ptr,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2678 PNG_FILTER_HEURISTIC_WEIGHTED, 3,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2679 weights, costs);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2680
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2681 The weights are multiplying factors that indicate to libpng that the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2682 row filter should be the same for successive rows unless another row filter
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2683 is that many times better than the previous filter. In the above example,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2684 if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2685 "sum of absolute differences" 1.5 x 1.3 times higher than other filters
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2686 and still be chosen, while the NONE filter could have a sum 1.1 times
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2687 higher than other filters and still be chosen. Unspecified weights are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2688 taken to be 1.0, and the specified weights should probably be declining
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2689 like those above in order to emphasize recent filters over older filters.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2690
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2691 The filter costs specify for each filter type a relative decoding cost
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2692 to be considered when selecting row filters. This means that filters
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2693 with higher costs are less likely to be chosen over filters with lower
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2694 costs, unless their "sum of absolute differences" is that much smaller.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2695 The costs do not necessarily reflect the exact computational speeds of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2696 the various filters, since this would unduly influence the final image
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2697 size.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2698
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2699 Note that the numbers above were invented purely for this example and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2700 are given only to help explain the function usage. Little testing has
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2701 been done to find optimum values for either the costs or the weights.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2702
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2703 Removing unwanted object code
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2704
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2705 There are a bunch of #define's in pngconf.h that control what parts of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2706 libpng are compiled. All the defines end in _SUPPORTED. If you are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2707 never going to use a capability, you can change the #define to #undef
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2708 before recompiling libpng and save yourself code and data space, or
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2709 you can turn off individual capabilities with defines that begin with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2710 PNG_NO_.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2711
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2712 You can also turn all of the transforms and ancillary chunk capabilities
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2713 off en masse with compiler directives that define
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2714 PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2715 or all four,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2716 along with directives to turn on any of the capabilities that you do
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2717 want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2718 the extra transformations but still leave the library fully capable of reading
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2719 and writing PNG files with all known public chunks
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2720 Use of the PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2721 produces a library that is incapable of reading or writing ancillary chunks.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2722 If you are not using the progressive reading capability, you can
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2723 turn that off with PNG_NO_PROGRESSIVE_READ (don't confuse
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2724 this with the INTERLACING capability, which you'll still have).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2725
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2726 All the reading and writing specific code are in separate files, so the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2727 linker should only grab the files it needs. However, if you want to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2728 make sure, or if you are building a stand alone library, all the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2729 reading files start with pngr and all the writing files start with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2730 pngw. The files that don't match either (like png.c, pngtrans.c, etc.)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2731 are used for both reading and writing, and always need to be included.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2732 The progressive reader is in pngpread.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2733
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2734 If you are creating or distributing a dynamically linked library (a .so
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2735 or DLL file), you should not remove or disable any parts of the library,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2736 as this will cause applications linked with different versions of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2737 library to fail if they call functions not available in your library.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2738 The size of the library itself should not be an issue, because only
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2739 those sections that are actually used will be loaded into memory.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2740
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2741 Requesting debug printout
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2742
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2743 The macro definition PNG_DEBUG can be used to request debugging
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2744 printout. Set it to an integer value in the range 0 to 3. Higher
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2745 numbers result in increasing amounts of debugging information. The
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2746 information is printed to the "stderr" file, unless another file
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2747 name is specified in the PNG_DEBUG_FILE macro definition.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2748
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2749 When PNG_DEBUG > 0, the following functions (macros) become available:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2750
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2751 png_debug(level, message)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2752 png_debug1(level, message, p1)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2753 png_debug2(level, message, p1, p2)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2754
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2755 in which "level" is compared to PNG_DEBUG to decide whether to print
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2756 the message, "message" is the formatted string to be printed,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2757 and p1 and p2 are parameters that are to be embedded in the string
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2758 according to printf-style formatting directives. For example,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2759
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2760 png_debug1(2, "foo=%d\n", foo);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2761
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2762 is expanded to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2763
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2764 if(PNG_DEBUG > 2)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2765 fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2766
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2767 When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2768 can still use PNG_DEBUG to control your own debugging:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2769
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2770 #ifdef PNG_DEBUG
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2771 fprintf(stderr, ...
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2772 #endif
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2773
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2774 When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2775 having level = 0 will be printed. There aren't any such statements in
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2776 this version of libpng, but if you insert some they will be printed.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2777
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2778 VII. MNG support
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2779
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2780 The MNG specification (available at http://www.libpng.org/pub/mng) allows
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2781 certain extensions to PNG for PNG images that are embedded in MNG datastreams.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2782 Libpng can support some of these extensions. To enable them, use the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2783 png_permit_mng_features() function:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2784
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2785 feature_set = png_permit_mng_features(png_ptr, mask)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2786 mask is a png_uint_32 containing the bitwise OR of the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2787 features you want to enable. These include
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2788 PNG_FLAG_MNG_EMPTY_PLTE
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2789 PNG_FLAG_MNG_FILTER_64
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2790 PNG_ALL_MNG_FEATURES
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2791 feature_set is a png_uint_32 that is the bitwise AND of
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2792 your mask with the set of MNG features that is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2793 supported by the version of libpng that you are using.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2794
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2795 It is an error to use this function when reading or writing a standalone
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2796 PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2797 in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2798 and the MHDR and MEND chunks. Libpng does not provide support for these
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2799 or any other MNG chunks; your application must provide its own support for
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2800 them. You may wish to consider using libmng (available at
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2801 http://www.libmng.com) instead.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2802
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2803 VIII. Changes to Libpng from version 0.88
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2804
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2805 It should be noted that versions of libpng later than 0.96 are not
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2806 distributed by the original libpng author, Guy Schalnat, nor by
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2807 Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2808 distributed versions 0.89 through 0.96, but rather by another member
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2809 of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2810 still alive and well, but they have moved on to other things.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2811
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2812 The old libpng functions png_read_init(), png_write_init(),
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2813 png_info_init(), png_read_destroy(), and png_write_destroy() have been
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2814 moved to PNG_INTERNAL in version 0.95 to discourage their use. These
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2815 functions will be removed from libpng version 2.0.0.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2816
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2817 The preferred method of creating and initializing the libpng structures is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2818 via the png_create_read_struct(), png_create_write_struct(), and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2819 png_create_info_struct() because they isolate the size of the structures
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2820 from the application, allow version error checking, and also allow the
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2821 use of custom error handling routines during the initialization, which
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2822 the old functions do not. The functions png_read_destroy() and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2823 png_write_destroy() do not actually free the memory that libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2824 allocated for these structs, but just reset the data structures, so they
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2825 can be used instead of png_destroy_read_struct() and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2826 png_destroy_write_struct() if you feel there is too much system overhead
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2827 allocating and freeing the png_struct for each image read.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2828
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2829 Setting the error callbacks via png_set_message_fn() before
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2830 png_read_init() as was suggested in libpng-0.88 is no longer supported
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2831 because this caused applications that do not use custom error functions
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2832 to fail if the png_ptr was not initialized to zero. It is still possible
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2833 to set the error callbacks AFTER png_read_init(), or to change them with
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2834 png_set_error_fn(), which is essentially the same function, but with a new
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2835 name to force compilation errors with applications that try to use the old
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2836 method.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2837
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2838 Starting with version 1.0.7, you can find out which version of the library
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2839 you are using at run-time:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2840
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2841 png_uint_32 libpng_vn = png_access_version_number();
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2842
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2843 The number libpng_vn is constructed from the major version, minor
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2844 version with leading zero, and release number with leading zero,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2845 (e.g., libpng_vn for version 1.0.7 is 10007).
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2846
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2847 You can also check which version of png.h you used when compiling your
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2848 application:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2849
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2850 png_uint_32 application_vn = PNG_LIBPNG_VER;
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2851
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2852 IX. Y2K Compliance in libpng
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2853
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2854 May 8, 2008
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2855
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2856 Since the PNG Development group is an ad-hoc body, we can't make
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2857 an official declaration.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2858
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2859 This is your unofficial assurance that libpng from version 0.71 and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2860 upward through 1.2.29 are Y2K compliant. It is my belief that earlier
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2861 versions were also Y2K compliant.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2862
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2863 Libpng only has three year fields. One is a 2-byte unsigned integer that
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2864 will hold years up to 65535. The other two hold the date in text
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2865 format, and will hold years up to 9999.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2866
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2867 The integer is
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2868 "png_uint_16 year" in png_time_struct.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2869
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2870 The strings are
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2871 "png_charp time_buffer" in png_struct and
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2872 "near_time_buffer", which is a local character string in png.c.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2873
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2874 There are seven time-related functions:
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2875
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2876 png_convert_to_rfc_1123() in png.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2877 (formerly png_convert_to_rfc_1152() in error)
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2878 png_convert_from_struct_tm() in pngwrite.c, called
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2879 in pngwrite.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2880 png_convert_from_time_t() in pngwrite.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2881 png_get_tIME() in pngget.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2882 png_handle_tIME() in pngrutil.c, called in pngread.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2883 png_set_tIME() in pngset.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2884 png_write_tIME() in pngwutil.c, called in pngwrite.c
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2885
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2886 All appear to handle dates properly in a Y2K environment. The
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2887 png_convert_from_time_t() function calls gmtime() to convert from system
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2888 clock time, which returns (year - 1900), which we properly convert to
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2889 the full 4-digit year. There is a possibility that applications using
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2890 libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2891 function, or that they are incorrectly passing only a 2-digit year
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2892 instead of "year - 1900" into the png_convert_from_struct_tm() function,
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2893 but this is not under our control. The libpng documentation has always
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2894 stated that it works with 4-digit years, and the APIs have been
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2895 documented as such.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2896
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2897 The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2898 integer to hold the year, and can hold years as large as 65535.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2899
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2900 zlib, upon which libpng depends, is also Y2K compliant. It contains
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2901 no date-related code.
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2902
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2903
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2904 Glenn Randers-Pehrson
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2905 libpng maintainer
4a0efb7baf70 * Datasets becomes the new trunk and retires after that :-)
mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
parents:
diff changeset
2906 PNG Development Group