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2297
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1
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2 #if 0 /* in case someone actually tries to compile this */
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3
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4 /* example.c - an example of using libpng
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5 * Last changed in libpng 1.6.3 [July 18, 2013]
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6 * Maintained 1998-2013 Glenn Randers-Pehrson
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7 * Maintained 1996, 1997 Andreas Dilger)
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8 * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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9 * To the extent possible under law, the authors have waived
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10 * all copyright and related or neighboring rights to this file.
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11 * This work is published from: United States.
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12 */
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13
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14 /* This is an example of how to use libpng to read and write PNG files.
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15 * The file libpng-manual.txt is much more verbose then this. If you have not
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16 * read it, do so first. This was designed to be a starting point of an
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17 * implementation. This is not officially part of libpng, is hereby placed
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18 * in the public domain, and therefore does not require a copyright notice.
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19 *
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20 * This file does not currently compile, because it is missing certain
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21 * parts, like allocating memory to hold an image. You will have to
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22 * supply these parts to get it to compile. For an example of a minimal
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23 * working PNG reader/writer, see pngtest.c, included in this distribution;
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24 * see also the programs in the contrib directory.
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25 */
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26
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27 /* The simple, but restricted, approach to reading a PNG file or data stream
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28 * just requires two function calls, as in the following complete program.
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29 * Writing a file just needs one function call, so long as the data has an
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30 * appropriate layout.
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31 *
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32 * The following code reads PNG image data from a file and writes it, in a
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33 * potentially new format, to a new file. While this code will compile there is
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34 * minimal (insufficient) error checking; for a more realistic version look at
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35 * contrib/examples/pngtopng.c
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36 */
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37 #include <stddef.h>
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38 #include <stdlib.h>
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39 #include <string.h>
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40 #include <stdio.h>
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41 #include <png.h>
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42 #include <zlib.h>
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43
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44 int main(int argc, const char **argv)
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45 {
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46 if (argc == 3)
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47 {
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48 png_image image; /* The control structure used by libpng */
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49
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50 /* Initialize the 'png_image' structure. */
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51 memset(&image, 0, (sizeof image));
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52 image.version = PNG_IMAGE_VERSION;
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53
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54 /* The first argument is the file to read: */
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55 if (png_image_begin_read_from_file(&image, argv[1]))
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56 {
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57 png_bytep buffer;
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58
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59 /* Set the format in which to read the PNG file; this code chooses a
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60 * simple sRGB format with a non-associated alpha channel, adequate to
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61 * store most images.
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62 */
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63 image.format = PNG_FORMAT_RGBA;
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64
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65 /* Now allocate enough memory to hold the image in this format; the
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66 * PNG_IMAGE_SIZE macro uses the information about the image (width,
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67 * height and format) stored in 'image'.
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68 */
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69 buffer = malloc(PNG_IMAGE_SIZE(image));
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70
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71 /* If enough memory was available read the image in the desired format
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72 * then write the result out to the new file. 'background' is not
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73 * necessary when reading the image because the alpha channel is
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74 * preserved; if it were to be removed, for example if we requested
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75 * PNG_FORMAT_RGB, then either a solid background color would have to
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76 * be supplied or the output buffer would have to be initialized to the
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77 * actual background of the image.
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78 *
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79 * The fourth argument to png_image_finish_read is the 'row_stride' -
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80 * this is the number of components allocated for the image in each
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81 * row. It has to be at least as big as the value returned by
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82 * PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the
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83 * default, minimum, size using PNG_IMAGE_SIZE as above you can pass
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84 * zero.
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85 *
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86 * The final argument is a pointer to a buffer for the colormap;
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87 * colormaps have exactly the same format as a row of image pixels (so
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88 * you choose what format to make the colormap by setting
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89 * image.format). A colormap is only returned if
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90 * PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this
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91 * case NULL is passed as the final argument. If you do want to force
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92 * all images into an index/color-mapped format then you can use:
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93 *
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94 * PNG_IMAGE_COLORMAP_SIZE(image)
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95 *
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96 * to find the maximum size of the colormap in bytes.
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97 */
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98 if (buffer != NULL &&
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99 png_image_finish_read(&image, NULL/*background*/, buffer,
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100 0/*row_stride*/, NULL/*colormap*/))
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101 {
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102 /* Now write the image out to the second argument. In the write
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103 * call 'convert_to_8bit' allows 16-bit data to be squashed down to
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104 * 8 bits; this isn't necessary here because the original read was
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105 * to the 8-bit format.
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106 */
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107 if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
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108 buffer, 0/*row_stride*/, NULL/*colormap*/))
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109 {
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110 /* The image has been written successfully. */
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111 exit(0);
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112 }
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113 }
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114
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115 else
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116 {
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117 /* Calling png_free_image is optional unless the simplified API was
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118 * not run to completion. In this case if there wasn't enough
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119 * memory for 'buffer' we didn't complete the read, so we must free
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120 * the image:
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121 */
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122 if (buffer == NULL)
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123 png_free_image(&image);
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124
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125 else
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126 free(buffer);
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127 }
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128
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129 /* Something went wrong reading or writing the image. libpng stores a
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130 * textual message in the 'png_image' structure:
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131 */
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132 fprintf(stderr, "pngtopng: error: %s\n", image.message);
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133 exit (1);
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134 }
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135
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136 fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
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137 exit(1);
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138 }
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139
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140 /* That's it ;-) Of course you probably want to do more with PNG files than
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141 * just converting them all to 32-bit RGBA PNG files; you can do that between
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142 * the call to png_image_finish_read and png_image_write_to_file. You can also
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143 * ask for the image data to be presented in a number of different formats. You
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144 * do this by simply changing the 'format' parameter set before allocating the
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145 * buffer.
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146 *
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147 * The format parameter consists of five flags that define various aspects of
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148 * the image, you can simply add these together to get the format or you can use
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149 * one of the predefined macros from png.h (as above):
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150 *
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151 * PNG_FORMAT_FLAG_COLOR: if set the image will have three color components per
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152 * pixel (red, green and blue), if not set the image will just have one
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153 * luminance (grayscale) component.
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154 *
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155 * PNG_FORMAT_FLAG_ALPHA: if set each pixel in the image will have an additional
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156 * alpha value; a linear value that describes the degree the image pixel
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157 * covers (overwrites) the contents of the existing pixel on the display.
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158 *
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159 * PNG_FORMAT_FLAG_LINEAR: if set the components of each pixel will be returned
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160 * as a series of 16-bit linear values, if not set the components will be
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161 * returned as a series of 8-bit values encoded according to the 'sRGB'
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162 * standard. The 8-bit format is the normal format for images intended for
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163 * direct display, because almost all display devices do the inverse of the
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164 * sRGB transformation to the data they receive. The 16-bit format is more
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165 * common for scientific data and image data that must be further processed;
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166 * because it is linear simple math can be done on the component values.
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167 * Regardless of the setting of this flag the alpha channel is always linear,
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168 * although it will be 8 bits or 16 bits wide as specified by the flag.
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169 *
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170 * PNG_FORMAT_FLAG_BGR: if set the components of a color pixel will be returned
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171 * in the order blue, then green, then red. If not set the pixel components
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172 * are in the order red, then green, then blue.
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173 *
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174 * PNG_FORMAT_FLAG_AFIRST: if set the alpha channel (if present) precedes the
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175 * color or grayscale components. If not set the alpha channel follows the
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176 * components.
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177 *
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178 * You do not have to read directly from a file. You can read from memory or,
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179 * on systems that support it, from a <stdio.h> FILE*. This is controlled by
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180 * the particular png_image_read_from_ function you call at the start. Likewise
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181 * on write you can write to a FILE* if your system supports it. Check the
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182 * macro PNG_STDIO_SUPPORTED to see if stdio support has been included in your
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183 * libpng build.
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184 *
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185 * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data you may need to write it in
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186 * the 8-bit format for display. You do this by setting the convert_to_8bit
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187 * flag to 'true'.
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188 *
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189 * Don't repeatedly convert between the 8-bit and 16-bit forms. There is
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190 * significant data loss when 16-bit data is converted to the 8-bit encoding and
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191 * the current libpng implementation of convertion to 16-bit is also
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192 * significantly lossy. The latter will be fixed in the future, but the former
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193 * is unavoidable - the 8-bit format just doesn't have enough resolution.
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194 */
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195
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196 /* If your program needs more information from the PNG data it reads, or if you
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197 * need to do more complex transformations, or minimise transformations, on the
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198 * data you read, then you must use one of the several lower level libpng
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199 * interfaces.
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200 *
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201 * All these interfaces require that you do your own error handling - your
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202 * program must be able to arrange for control to return to your own code any
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203 * time libpng encounters a problem. There are several ways to do this, but the
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204 * standard way is to use the ANSI-C (C90) <setjmp.h> interface to establish a
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205 * return point within your own code. You must do this if you do not use the
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206 * simplified interface (above).
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207 *
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208 * The first step is to include the header files you need, including the libpng
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209 * header file. Include any standard headers and feature test macros your
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210 * program requires before including png.h:
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211 */
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212 #include <png.h>
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213
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214 /* The png_jmpbuf() macro, used in error handling, became available in
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215 * libpng version 1.0.6. If you want to be able to run your code with older
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216 * versions of libpng, you must define the macro yourself (but only if it
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217 * is not already defined by libpng!).
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218 */
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219
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220 #ifndef png_jmpbuf
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221 # define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf)
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222 #endif
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223
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224 /* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp()
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225 * returns zero if the image is a PNG and nonzero if it isn't a PNG.
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226 *
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227 * The function check_if_png() shown here, but not used, returns nonzero (true)
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228 * if the file can be opened and is a PNG, 0 (false) otherwise.
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229 *
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230 * If this call is successful, and you are going to keep the file open,
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231 * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
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232 * you have created the png_ptr, so that libpng knows your application
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233 * has read that many bytes from the start of the file. Make sure you
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234 * don't call png_set_sig_bytes() with more than 8 bytes read or give it
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235 * an incorrect number of bytes read, or you will either have read too
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236 * many bytes (your fault), or you are telling libpng to read the wrong
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237 * number of magic bytes (also your fault).
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238 *
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239 * Many applications already read the first 2 or 4 bytes from the start
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240 * of the image to determine the file type, so it would be easiest just
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241 * to pass the bytes to png_sig_cmp() or even skip that if you know
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242 * you have a PNG file, and call png_set_sig_bytes().
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243 */
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244 #define PNG_BYTES_TO_CHECK 4
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245 int check_if_png(char *file_name, FILE **fp)
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246 {
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247 char buf[PNG_BYTES_TO_CHECK];
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248
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249 /* Open the prospective PNG file. */
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250 if ((*fp = fopen(file_name, "rb")) == NULL)
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251 return 0;
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252
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253 /* Read in some of the signature bytes */
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254 if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
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255 return 0;
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256
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257 /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
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258 Return nonzero (true) if they match */
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259
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260 return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
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261 }
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262
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263 /* Read a PNG file. You may want to return an error code if the read
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264 * fails (depending upon the failure). There are two "prototypes" given
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265 * here - one where we are given the filename, and we need to open the
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266 * file, and the other where we are given an open file (possibly with
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267 * some or all of the magic bytes read - see comments above).
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268 */
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269 #ifdef open_file /* prototype 1 */
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270 void read_png(char *file_name) /* We need to open the file */
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271 {
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272 png_structp png_ptr;
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273 png_infop info_ptr;
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274 unsigned int sig_read = 0;
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275 png_uint_32 width, height;
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276 int bit_depth, color_type, interlace_type;
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277 FILE *fp;
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278
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279 if ((fp = fopen(file_name, "rb")) == NULL)
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280 return (ERROR);
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281
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282 #else no_open_file /* prototype 2 */
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283 void read_png(FILE *fp, unsigned int sig_read) /* File is already open */
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284 {
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285 png_structp png_ptr;
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286 png_infop info_ptr;
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287 png_uint_32 width, height;
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288 int bit_depth, color_type, interlace_type;
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289 #endif no_open_file /* Only use one prototype! */
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290
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291 /* Create and initialize the png_struct with the desired error handler
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292 * functions. If you want to use the default stderr and longjump method,
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293 * you can supply NULL for the last three parameters. We also supply the
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294 * the compiler header file version, so that we know if the application
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295 * was compiled with a compatible version of the library. REQUIRED
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296 */
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297 png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
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298 png_voidp user_error_ptr, user_error_fn, user_warning_fn);
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299
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300 if (png_ptr == NULL)
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301 {
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302 fclose(fp);
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303 return (ERROR);
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304 }
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305
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306 /* Allocate/initialize the memory for image information. REQUIRED. */
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307 info_ptr = png_create_info_struct(png_ptr);
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308 if (info_ptr == NULL)
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309 {
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310 fclose(fp);
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311 png_destroy_read_struct(&png_ptr, NULL, NULL);
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312 return (ERROR);
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313 }
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314
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315 /* Set error handling if you are using the setjmp/longjmp method (this is
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316 * the normal method of doing things with libpng). REQUIRED unless you
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317 * set up your own error handlers in the png_create_read_struct() earlier.
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318 */
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319
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320 if (setjmp(png_jmpbuf(png_ptr)))
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321 {
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322 /* Free all of the memory associated with the png_ptr and info_ptr */
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323 png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
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324 fclose(fp);
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325 /* If we get here, we had a problem reading the file */
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326 return (ERROR);
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327 }
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328
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329 /* One of the following I/O initialization methods is REQUIRED */
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330 #ifdef streams /* PNG file I/O method 1 */
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331 /* Set up the input control if you are using standard C streams */
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332 png_init_io(png_ptr, fp);
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333
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334 #else no_streams /* PNG file I/O method 2 */
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335 /* If you are using replacement read functions, instead of calling
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336 * png_init_io() here you would call:
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337 */
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338 png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
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339 /* where user_io_ptr is a structure you want available to the callbacks */
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340 #endif no_streams /* Use only one I/O method! */
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341
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342 /* If we have already read some of the signature */
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343 png_set_sig_bytes(png_ptr, sig_read);
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344
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345 #ifdef hilevel
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346 /*
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347 * If you have enough memory to read in the entire image at once,
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348 * and you need to specify only transforms that can be controlled
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349 * with one of the PNG_TRANSFORM_* bits (this presently excludes
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350 * quantizing, filling, setting background, and doing gamma
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351 * adjustment), then you can read the entire image (including
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352 * pixels) into the info structure with this call:
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353 */
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354 png_read_png(png_ptr, info_ptr, png_transforms, NULL);
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355
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356 #else
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357 /* OK, you're doing it the hard way, with the lower-level functions */
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358
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359 /* The call to png_read_info() gives us all of the information from the
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360 * PNG file before the first IDAT (image data chunk). REQUIRED
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361 */
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362 png_read_info(png_ptr, info_ptr);
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363
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364 png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
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365 &interlace_type, NULL, NULL);
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366
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367 /* Set up the data transformations you want. Note that these are all
|
|
|
368 * optional. Only call them if you want/need them. Many of the
|
|
|
369 * transformations only work on specific types of images, and many
|
|
|
370 * are mutually exclusive.
|
|
|
371 */
|
|
|
372
|
|
|
373 /* Tell libpng to strip 16 bit/color files down to 8 bits/color.
|
|
|
374 * Use accurate scaling if it's available, otherwise just chop off the
|
|
|
375 * low byte.
|
|
|
376 */
|
|
|
377 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
|
|
|
378 png_set_scale_16(png_ptr);
|
|
|
379 #else
|
|
|
380 png_set_strip_16(png_ptr);
|
|
|
381 #endif
|
|
|
382
|
|
|
383 /* Strip alpha bytes from the input data without combining with the
|
|
|
384 * background (not recommended).
|
|
|
385 */
|
|
|
386 png_set_strip_alpha(png_ptr);
|
|
|
387
|
|
|
388 /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
|
|
|
389 * byte into separate bytes (useful for paletted and grayscale images).
|
|
|
390 */
|
|
|
391 png_set_packing(png_ptr);
|
|
|
392
|
|
|
393 /* Change the order of packed pixels to least significant bit first
|
|
|
394 * (not useful if you are using png_set_packing). */
|
|
|
395 png_set_packswap(png_ptr);
|
|
|
396
|
|
|
397 /* Expand paletted colors into true RGB triplets */
|
|
|
398 if (color_type == PNG_COLOR_TYPE_PALETTE)
|
|
|
399 png_set_palette_to_rgb(png_ptr);
|
|
|
400
|
|
|
401 /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
|
|
|
402 if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
|
|
|
403 png_set_expand_gray_1_2_4_to_8(png_ptr);
|
|
|
404
|
|
|
405 /* Expand paletted or RGB images with transparency to full alpha channels
|
|
|
406 * so the data will be available as RGBA quartets.
|
|
|
407 */
|
|
|
408 if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
|
|
|
409 png_set_tRNS_to_alpha(png_ptr);
|
|
|
410
|
|
|
411 /* Set the background color to draw transparent and alpha images over.
|
|
|
412 * It is possible to set the red, green, and blue components directly
|
|
|
413 * for paletted images instead of supplying a palette index. Note that
|
|
|
414 * even if the PNG file supplies a background, you are not required to
|
|
|
415 * use it - you should use the (solid) application background if it has one.
|
|
|
416 */
|
|
|
417
|
|
|
418 png_color_16 my_background, *image_background;
|
|
|
419
|
|
|
420 if (png_get_bKGD(png_ptr, info_ptr, &image_background))
|
|
|
421 png_set_background(png_ptr, image_background,
|
|
|
422 PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
|
|
|
423 else
|
|
|
424 png_set_background(png_ptr, &my_background,
|
|
|
425 PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
|
|
|
426
|
|
|
427 /* Some suggestions as to how to get a screen gamma value
|
|
|
428 *
|
|
|
429 * Note that screen gamma is the display_exponent, which includes
|
|
|
430 * the CRT_exponent and any correction for viewing conditions
|
|
|
431 */
|
|
|
432 if (/* We have a user-defined screen gamma value */)
|
|
|
433 {
|
|
|
434 screen_gamma = user-defined screen_gamma;
|
|
|
435 }
|
|
|
436 /* This is one way that applications share the same screen gamma value */
|
|
|
437 else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
|
|
|
438 {
|
|
|
439 screen_gamma = atof(gamma_str);
|
|
|
440 }
|
|
|
441 /* If we don't have another value */
|
|
|
442 else
|
|
|
443 {
|
|
|
444 screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor
|
|
|
445 in a dimly lit room */
|
|
|
446 screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */
|
|
|
447 }
|
|
|
448
|
|
|
449 /* Tell libpng to handle the gamma conversion for you. The final call
|
|
|
450 * is a good guess for PC generated images, but it should be configurable
|
|
|
451 * by the user at run time by the user. It is strongly suggested that
|
|
|
452 * your application support gamma correction.
|
|
|
453 */
|
|
|
454
|
|
|
455 int intent;
|
|
|
456
|
|
|
457 if (png_get_sRGB(png_ptr, info_ptr, &intent))
|
|
|
458 png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB);
|
|
|
459 else
|
|
|
460 {
|
|
|
461 double image_gamma;
|
|
|
462 if (png_get_gAMA(png_ptr, info_ptr, &image_gamma))
|
|
|
463 png_set_gamma(png_ptr, screen_gamma, image_gamma);
|
|
|
464 else
|
|
|
465 png_set_gamma(png_ptr, screen_gamma, 0.45455);
|
|
|
466 }
|
|
|
467
|
|
|
468 #ifdef PNG_READ_QUANTIZE_SUPPORTED
|
|
|
469 /* Quantize RGB files down to 8 bit palette or reduce palettes
|
|
|
470 * to the number of colors available on your screen.
|
|
|
471 */
|
|
|
472 if (color_type & PNG_COLOR_MASK_COLOR)
|
|
|
473 {
|
|
|
474 int num_palette;
|
|
|
475 png_colorp palette;
|
|
|
476
|
|
|
477 /* This reduces the image to the application supplied palette */
|
|
|
478 if (/* We have our own palette */)
|
|
|
479 {
|
|
|
480 /* An array of colors to which the image should be quantized */
|
|
|
481 png_color std_color_cube[MAX_SCREEN_COLORS];
|
|
|
482
|
|
|
483 png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
|
|
|
484 MAX_SCREEN_COLORS, NULL, 0);
|
|
|
485 }
|
|
|
486 /* This reduces the image to the palette supplied in the file */
|
|
|
487 else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette))
|
|
|
488 {
|
|
|
489 png_uint_16p histogram = NULL;
|
|
|
490
|
|
|
491 png_get_hIST(png_ptr, info_ptr, &histogram);
|
|
|
492
|
|
|
493 png_set_quantize(png_ptr, palette, num_palette,
|
|
|
494 max_screen_colors, histogram, 0);
|
|
|
495 }
|
|
|
496 }
|
|
|
497 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
|
|
|
498
|
|
|
499 /* Invert monochrome files to have 0 as white and 1 as black */
|
|
|
500 png_set_invert_mono(png_ptr);
|
|
|
501
|
|
|
502 /* If you want to shift the pixel values from the range [0,255] or
|
|
|
503 * [0,65535] to the original [0,7] or [0,31], or whatever range the
|
|
|
504 * colors were originally in:
|
|
|
505 */
|
|
|
506 if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT))
|
|
|
507 {
|
|
|
508 png_color_8p sig_bit_p;
|
|
|
509
|
|
|
510 png_get_sBIT(png_ptr, info_ptr, &sig_bit_p);
|
|
|
511 png_set_shift(png_ptr, sig_bit_p);
|
|
|
512 }
|
|
|
513
|
|
|
514 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
|
|
|
515 if (color_type & PNG_COLOR_MASK_COLOR)
|
|
|
516 png_set_bgr(png_ptr);
|
|
|
517
|
|
|
518 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
|
|
|
519 png_set_swap_alpha(png_ptr);
|
|
|
520
|
|
|
521 /* Swap bytes of 16 bit files to least significant byte first */
|
|
|
522 png_set_swap(png_ptr);
|
|
|
523
|
|
|
524 /* Add filler (or alpha) byte (before/after each RGB triplet) */
|
|
|
525 png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
|
|
|
526
|
|
|
527 #ifdef PNG_READ_INTERLACING_SUPPORTED
|
|
|
528 /* Turn on interlace handling. REQUIRED if you are not using
|
|
|
529 * png_read_image(). To see how to handle interlacing passes,
|
|
|
530 * see the png_read_row() method below:
|
|
|
531 */
|
|
|
532 number_passes = png_set_interlace_handling(png_ptr);
|
|
|
533 #else
|
|
|
534 number_passes = 1;
|
|
|
535 #endif /* PNG_READ_INTERLACING_SUPPORTED */
|
|
|
536
|
|
|
537
|
|
|
538 /* Optional call to gamma correct and add the background to the palette
|
|
|
539 * and update info structure. REQUIRED if you are expecting libpng to
|
|
|
540 * update the palette for you (ie you selected such a transform above).
|
|
|
541 */
|
|
|
542 png_read_update_info(png_ptr, info_ptr);
|
|
|
543
|
|
|
544 /* Allocate the memory to hold the image using the fields of info_ptr. */
|
|
|
545
|
|
|
546 /* The easiest way to read the image: */
|
|
|
547 png_bytep row_pointers[height];
|
|
|
548
|
|
|
549 /* Clear the pointer array */
|
|
|
550 for (row = 0; row < height; row++)
|
|
|
551 row_pointers[row] = NULL;
|
|
|
552
|
|
|
553 for (row = 0; row < height; row++)
|
|
|
554 row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
|
|
|
555 info_ptr));
|
|
|
556
|
|
|
557 /* Now it's time to read the image. One of these methods is REQUIRED */
|
|
|
558 #ifdef entire /* Read the entire image in one go */
|
|
|
559 png_read_image(png_ptr, row_pointers);
|
|
|
560
|
|
|
561 #else no_entire /* Read the image one or more scanlines at a time */
|
|
|
562 /* The other way to read images - deal with interlacing: */
|
|
|
563
|
|
|
564 for (pass = 0; pass < number_passes; pass++)
|
|
|
565 {
|
|
|
566 #ifdef single /* Read the image a single row at a time */
|
|
|
567 for (y = 0; y < height; y++)
|
|
|
568 {
|
|
|
569 png_read_rows(png_ptr, &row_pointers[y], NULL, 1);
|
|
|
570 }
|
|
|
571
|
|
|
572 #else no_single /* Read the image several rows at a time */
|
|
|
573 for (y = 0; y < height; y += number_of_rows)
|
|
|
574 {
|
|
|
575 #ifdef sparkle /* Read the image using the "sparkle" effect. */
|
|
|
576 png_read_rows(png_ptr, &row_pointers[y], NULL,
|
|
|
577 number_of_rows);
|
|
|
578 #else no_sparkle /* Read the image using the "rectangle" effect */
|
|
|
579 png_read_rows(png_ptr, NULL, &row_pointers[y],
|
|
|
580 number_of_rows);
|
|
|
581 #endif no_sparkle /* Use only one of these two methods */
|
|
|
582 }
|
|
|
583
|
|
|
584 /* If you want to display the image after every pass, do so here */
|
|
|
585 #endif no_single /* Use only one of these two methods */
|
|
|
586 }
|
|
|
587 #endif no_entire /* Use only one of these two methods */
|
|
|
588
|
|
|
589 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
|
|
|
590 png_read_end(png_ptr, info_ptr);
|
|
|
591 #endif hilevel
|
|
|
592
|
|
|
593 /* At this point you have read the entire image */
|
|
|
594
|
|
|
595 /* Clean up after the read, and free any memory allocated - REQUIRED */
|
|
|
596 png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
|
|
|
597
|
|
|
598 /* Close the file */
|
|
|
599 fclose(fp);
|
|
|
600
|
|
|
601 /* That's it */
|
|
|
602 return (OK);
|
|
|
603 }
|
|
|
604
|
|
|
605 /* Progressively read a file */
|
|
|
606
|
|
|
607 int
|
|
|
608 initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
|
|
|
609 {
|
|
|
610 /* Create and initialize the png_struct with the desired error handler
|
|
|
611 * functions. If you want to use the default stderr and longjump method,
|
|
|
612 * you can supply NULL for the last three parameters. We also check that
|
|
|
613 * the library version is compatible in case we are using dynamically
|
|
|
614 * linked libraries.
|
|
|
615 */
|
|
|
616 *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
|
|
|
617 png_voidp user_error_ptr, user_error_fn, user_warning_fn);
|
|
|
618
|
|
|
619 if (*png_ptr == NULL)
|
|
|
620 {
|
|
|
621 *info_ptr = NULL;
|
|
|
622 return (ERROR);
|
|
|
623 }
|
|
|
624
|
|
|
625 *info_ptr = png_create_info_struct(png_ptr);
|
|
|
626
|
|
|
627 if (*info_ptr == NULL)
|
|
|
628 {
|
|
|
629 png_destroy_read_struct(png_ptr, info_ptr, NULL);
|
|
|
630 return (ERROR);
|
|
|
631 }
|
|
|
632
|
|
|
633 if (setjmp(png_jmpbuf((*png_ptr))))
|
|
|
634 {
|
|
|
635 png_destroy_read_struct(png_ptr, info_ptr, NULL);
|
|
|
636 return (ERROR);
|
|
|
637 }
|
|
|
638
|
|
|
639 /* This one's new. You will need to provide all three
|
|
|
640 * function callbacks, even if you aren't using them all.
|
|
|
641 * If you aren't using all functions, you can specify NULL
|
|
|
642 * parameters. Even when all three functions are NULL,
|
|
|
643 * you need to call png_set_progressive_read_fn().
|
|
|
644 * These functions shouldn't be dependent on global or
|
|
|
645 * static variables if you are decoding several images
|
|
|
646 * simultaneously. You should store stream specific data
|
|
|
647 * in a separate struct, given as the second parameter,
|
|
|
648 * and retrieve the pointer from inside the callbacks using
|
|
|
649 * the function png_get_progressive_ptr(png_ptr).
|
|
|
650 */
|
|
|
651 png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
|
|
|
652 info_callback, row_callback, end_callback);
|
|
|
653
|
|
|
654 return (OK);
|
|
|
655 }
|
|
|
656
|
|
|
657 int
|
|
|
658 process_data(png_structp *png_ptr, png_infop *info_ptr,
|
|
|
659 png_bytep buffer, png_uint_32 length)
|
|
|
660 {
|
|
|
661 if (setjmp(png_jmpbuf((*png_ptr))))
|
|
|
662 {
|
|
|
663 /* Free the png_ptr and info_ptr memory on error */
|
|
|
664 png_destroy_read_struct(png_ptr, info_ptr, NULL);
|
|
|
665 return (ERROR);
|
|
|
666 }
|
|
|
667
|
|
|
668 /* This one's new also. Simply give it chunks of data as
|
|
|
669 * they arrive from the data stream (in order, of course).
|
|
|
670 * On segmented machines, don't give it any more than 64K.
|
|
|
671 * The library seems to run fine with sizes of 4K, although
|
|
|
672 * you can give it much less if necessary (I assume you can
|
|
|
673 * give it chunks of 1 byte, but I haven't tried with less
|
|
|
674 * than 256 bytes yet). When this function returns, you may
|
|
|
675 * want to display any rows that were generated in the row
|
|
|
676 * callback, if you aren't already displaying them there.
|
|
|
677 */
|
|
|
678 png_process_data(*png_ptr, *info_ptr, buffer, length);
|
|
|
679 return (OK);
|
|
|
680 }
|
|
|
681
|
|
|
682 info_callback(png_structp png_ptr, png_infop info)
|
|
|
683 {
|
|
|
684 /* Do any setup here, including setting any of the transformations
|
|
|
685 * mentioned in the Reading PNG files section. For now, you _must_
|
|
|
686 * call either png_start_read_image() or png_read_update_info()
|
|
|
687 * after all the transformations are set (even if you don't set
|
|
|
688 * any). You may start getting rows before png_process_data()
|
|
|
689 * returns, so this is your last chance to prepare for that.
|
|
|
690 */
|
|
|
691 }
|
|
|
692
|
|
|
693 row_callback(png_structp png_ptr, png_bytep new_row,
|
|
|
694 png_uint_32 row_num, int pass)
|
|
|
695 {
|
|
|
696 /*
|
|
|
697 * This function is called for every row in the image. If the
|
|
|
698 * image is interlaced, and you turned on the interlace handler,
|
|
|
699 * this function will be called for every row in every pass.
|
|
|
700 *
|
|
|
701 * In this function you will receive a pointer to new row data from
|
|
|
702 * libpng called new_row that is to replace a corresponding row (of
|
|
|
703 * the same data format) in a buffer allocated by your application.
|
|
|
704 *
|
|
|
705 * The new row data pointer "new_row" may be NULL, indicating there is
|
|
|
706 * no new data to be replaced (in cases of interlace loading).
|
|
|
707 *
|
|
|
708 * If new_row is not NULL then you need to call
|
|
|
709 * png_progressive_combine_row() to replace the corresponding row as
|
|
|
710 * shown below:
|
|
|
711 */
|
|
|
712
|
|
|
713 /* Get pointer to corresponding row in our
|
|
|
714 * PNG read buffer.
|
|
|
715 */
|
|
|
716 png_bytep old_row = ((png_bytep *)our_data)[row_num];
|
|
|
717
|
|
|
718 #ifdef PNG_READ_INTERLACING_SUPPORTED
|
|
|
719 /* If both rows are allocated then copy the new row
|
|
|
720 * data to the corresponding row data.
|
|
|
721 */
|
|
|
722 if ((old_row != NULL) && (new_row != NULL))
|
|
|
723 png_progressive_combine_row(png_ptr, old_row, new_row);
|
|
|
724
|
|
|
725 /*
|
|
|
726 * The rows and passes are called in order, so you don't really
|
|
|
727 * need the row_num and pass, but I'm supplying them because it
|
|
|
728 * may make your life easier.
|
|
|
729 *
|
|
|
730 * For the non-NULL rows of interlaced images, you must call
|
|
|
731 * png_progressive_combine_row() passing in the new row and the
|
|
|
732 * old row, as demonstrated above. You can call this function for
|
|
|
733 * NULL rows (it will just return) and for non-interlaced images
|
|
|
734 * (it just does the memcpy for you) if it will make the code
|
|
|
735 * easier. Thus, you can just do this for all cases:
|
|
|
736 */
|
|
|
737
|
|
|
738 png_progressive_combine_row(png_ptr, old_row, new_row);
|
|
|
739
|
|
|
740 /* where old_row is what was displayed for previous rows. Note
|
|
|
741 * that the first pass (pass == 0 really) will completely cover
|
|
|
742 * the old row, so the rows do not have to be initialized. After
|
|
|
743 * the first pass (and only for interlaced images), you will have
|
|
|
744 * to pass the current row as new_row, and the function will combine
|
|
|
745 * the old row and the new row.
|
|
|
746 */
|
|
|
747 #endif /* PNG_READ_INTERLACING_SUPPORTED */
|
|
|
748 }
|
|
|
749
|
|
|
750 end_callback(png_structp png_ptr, png_infop info)
|
|
|
751 {
|
|
|
752 /* This function is called when the whole image has been read,
|
|
|
753 * including any chunks after the image (up to and including
|
|
|
754 * the IEND). You will usually have the same info chunk as you
|
|
|
755 * had in the header, although some data may have been added
|
|
|
756 * to the comments and time fields.
|
|
|
757 *
|
|
|
758 * Most people won't do much here, perhaps setting a flag that
|
|
|
759 * marks the image as finished.
|
|
|
760 */
|
|
|
761 }
|
|
|
762
|
|
|
763 /* Write a png file */
|
|
|
764 void write_png(char *file_name /* , ... other image information ... */)
|
|
|
765 {
|
|
|
766 FILE *fp;
|
|
|
767 png_structp png_ptr;
|
|
|
768 png_infop info_ptr;
|
|
|
769 png_colorp palette;
|
|
|
770
|
|
|
771 /* Open the file */
|
|
|
772 fp = fopen(file_name, "wb");
|
|
|
773 if (fp == NULL)
|
|
|
774 return (ERROR);
|
|
|
775
|
|
|
776 /* Create and initialize the png_struct with the desired error handler
|
|
|
777 * functions. If you want to use the default stderr and longjump method,
|
|
|
778 * you can supply NULL for the last three parameters. We also check that
|
|
|
779 * the library version is compatible with the one used at compile time,
|
|
|
780 * in case we are using dynamically linked libraries. REQUIRED.
|
|
|
781 */
|
|
|
782 png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
|
|
|
783 png_voidp user_error_ptr, user_error_fn, user_warning_fn);
|
|
|
784
|
|
|
785 if (png_ptr == NULL)
|
|
|
786 {
|
|
|
787 fclose(fp);
|
|
|
788 return (ERROR);
|
|
|
789 }
|
|
|
790
|
|
|
791 /* Allocate/initialize the image information data. REQUIRED */
|
|
|
792 info_ptr = png_create_info_struct(png_ptr);
|
|
|
793 if (info_ptr == NULL)
|
|
|
794 {
|
|
|
795 fclose(fp);
|
|
|
796 png_destroy_write_struct(&png_ptr, NULL);
|
|
|
797 return (ERROR);
|
|
|
798 }
|
|
|
799
|
|
|
800 /* Set error handling. REQUIRED if you aren't supplying your own
|
|
|
801 * error handling functions in the png_create_write_struct() call.
|
|
|
802 */
|
|
|
803 if (setjmp(png_jmpbuf(png_ptr)))
|
|
|
804 {
|
|
|
805 /* If we get here, we had a problem writing the file */
|
|
|
806 fclose(fp);
|
|
|
807 png_destroy_write_struct(&png_ptr, &info_ptr);
|
|
|
808 return (ERROR);
|
|
|
809 }
|
|
|
810
|
|
|
811 /* One of the following I/O initialization functions is REQUIRED */
|
|
|
812
|
|
|
813 #ifdef streams /* I/O initialization method 1 */
|
|
|
814 /* Set up the output control if you are using standard C streams */
|
|
|
815 png_init_io(png_ptr, fp);
|
|
|
816
|
|
|
817 #else no_streams /* I/O initialization method 2 */
|
|
|
818 /* If you are using replacement write functions, instead of calling
|
|
|
819 * png_init_io() here you would call
|
|
|
820 */
|
|
|
821 png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
|
|
|
822 user_IO_flush_function);
|
|
|
823 /* where user_io_ptr is a structure you want available to the callbacks */
|
|
|
824 #endif no_streams /* Only use one initialization method */
|
|
|
825
|
|
|
826 #ifdef hilevel
|
|
|
827 /* This is the easy way. Use it if you already have all the
|
|
|
828 * image info living in the structure. You could "|" many
|
|
|
829 * PNG_TRANSFORM flags into the png_transforms integer here.
|
|
|
830 */
|
|
|
831 png_write_png(png_ptr, info_ptr, png_transforms, NULL);
|
|
|
832
|
|
|
833 #else
|
|
|
834 /* This is the hard way */
|
|
|
835
|
|
|
836 /* Set the image information here. Width and height are up to 2^31,
|
|
|
837 * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
|
|
|
838 * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
|
|
|
839 * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
|
|
|
840 * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or
|
|
|
841 * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
|
|
|
842 * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
|
|
|
843 */
|
|
|
844 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
|
|
|
845 PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
|
|
|
846
|
|
|
847 /* Set the palette if there is one. REQUIRED for indexed-color images */
|
|
|
848 palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
|
|
|
849 * (sizeof (png_color)));
|
|
|
850 /* ... Set palette colors ... */
|
|
|
851 png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
|
|
|
852 /* You must not free palette here, because png_set_PLTE only makes a link to
|
|
|
853 * the palette that you malloced. Wait until you are about to destroy
|
|
|
854 * the png structure.
|
|
|
855 */
|
|
|
856
|
|
|
857 /* Optional significant bit (sBIT) chunk */
|
|
|
858 png_color_8 sig_bit;
|
|
|
859
|
|
|
860 /* If we are dealing with a grayscale image then */
|
|
|
861 sig_bit.gray = true_bit_depth;
|
|
|
862
|
|
|
863 /* Otherwise, if we are dealing with a color image then */
|
|
|
864 sig_bit.red = true_red_bit_depth;
|
|
|
865 sig_bit.green = true_green_bit_depth;
|
|
|
866 sig_bit.blue = true_blue_bit_depth;
|
|
|
867
|
|
|
868 /* If the image has an alpha channel then */
|
|
|
869 sig_bit.alpha = true_alpha_bit_depth;
|
|
|
870
|
|
|
871 png_set_sBIT(png_ptr, info_ptr, &sig_bit);
|
|
|
872
|
|
|
873
|
|
|
874 /* Optional gamma chunk is strongly suggested if you have any guess
|
|
|
875 * as to the correct gamma of the image.
|
|
|
876 */
|
|
|
877 png_set_gAMA(png_ptr, info_ptr, gamma);
|
|
|
878
|
|
|
879 /* Optionally write comments into the image */
|
|
|
880 {
|
|
|
881 png_text text_ptr[3];
|
|
|
882
|
|
|
883 char key0[]="Title";
|
|
|
884 char text0[]="Mona Lisa";
|
|
|
885 text_ptr[0].key = key0;
|
|
|
886 text_ptr[0].text = text0;
|
|
|
887 text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
|
|
|
888 text_ptr[0].itxt_length = 0;
|
|
|
889 text_ptr[0].lang = NULL;
|
|
|
890 text_ptr[0].lang_key = NULL;
|
|
|
891
|
|
|
892 char key1[]="Author";
|
|
|
893 char text1[]="Leonardo DaVinci";
|
|
|
894 text_ptr[1].key = key1;
|
|
|
895 text_ptr[1].text = text1;
|
|
|
896 text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
|
|
|
897 text_ptr[1].itxt_length = 0;
|
|
|
898 text_ptr[1].lang = NULL;
|
|
|
899 text_ptr[1].lang_key = NULL;
|
|
|
900
|
|
|
901 char key2[]="Description";
|
|
|
902 char text2[]="<long text>";
|
|
|
903 text_ptr[2].key = key2;
|
|
|
904 text_ptr[2].text = text2;
|
|
|
905 text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
|
|
|
906 text_ptr[2].itxt_length = 0;
|
|
|
907 text_ptr[2].lang = NULL;
|
|
|
908 text_ptr[2].lang_key = NULL;
|
|
|
909
|
|
|
910 png_set_text(write_ptr, write_info_ptr, text_ptr, 3);
|
|
|
911 }
|
|
|
912
|
|
|
913 /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */
|
|
|
914
|
|
|
915 /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored
|
|
|
916 * on read and, if your application chooses to write them, they must
|
|
|
917 * be written in accordance with the sRGB profile
|
|
|
918 */
|
|
|
919
|
|
|
920 /* Write the file header information. REQUIRED */
|
|
|
921 png_write_info(png_ptr, info_ptr);
|
|
|
922
|
|
|
923 /* If you want, you can write the info in two steps, in case you need to
|
|
|
924 * write your private chunk ahead of PLTE:
|
|
|
925 *
|
|
|
926 * png_write_info_before_PLTE(write_ptr, write_info_ptr);
|
|
|
927 * write_my_chunk();
|
|
|
928 * png_write_info(png_ptr, info_ptr);
|
|
|
929 *
|
|
|
930 * However, given the level of known- and unknown-chunk support in 1.2.0
|
|
|
931 * and up, this should no longer be necessary.
|
|
|
932 */
|
|
|
933
|
|
|
934 /* Once we write out the header, the compression type on the text
|
|
|
935 * chunks gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
|
|
|
936 * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
|
|
|
937 * at the end.
|
|
|
938 */
|
|
|
939
|
|
|
940 /* Set up the transformations you want. Note that these are
|
|
|
941 * all optional. Only call them if you want them.
|
|
|
942 */
|
|
|
943
|
|
|
944 /* Invert monochrome pixels */
|
|
|
945 png_set_invert_mono(png_ptr);
|
|
|
946
|
|
|
947 /* Shift the pixels up to a legal bit depth and fill in
|
|
|
948 * as appropriate to correctly scale the image.
|
|
|
949 */
|
|
|
950 png_set_shift(png_ptr, &sig_bit);
|
|
|
951
|
|
|
952 /* Pack pixels into bytes */
|
|
|
953 png_set_packing(png_ptr);
|
|
|
954
|
|
|
955 /* Swap location of alpha bytes from ARGB to RGBA */
|
|
|
956 png_set_swap_alpha(png_ptr);
|
|
|
957
|
|
|
958 /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
|
|
|
959 * RGB (4 channels -> 3 channels). The second parameter is not used.
|
|
|
960 */
|
|
|
961 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
|
|
|
962
|
|
|
963 /* Flip BGR pixels to RGB */
|
|
|
964 png_set_bgr(png_ptr);
|
|
|
965
|
|
|
966 /* Swap bytes of 16-bit files to most significant byte first */
|
|
|
967 png_set_swap(png_ptr);
|
|
|
968
|
|
|
969 /* Swap bits of 1, 2, 4 bit packed pixel formats */
|
|
|
970 png_set_packswap(png_ptr);
|
|
|
971
|
|
|
972 /* Turn on interlace handling if you are not using png_write_image() */
|
|
|
973 if (interlacing)
|
|
|
974 number_passes = png_set_interlace_handling(png_ptr);
|
|
|
975
|
|
|
976 else
|
|
|
977 number_passes = 1;
|
|
|
978
|
|
|
979 /* The easiest way to write the image (you may have a different memory
|
|
|
980 * layout, however, so choose what fits your needs best). You need to
|
|
|
981 * use the first method if you aren't handling interlacing yourself.
|
|
|
982 */
|
|
|
983 png_uint_32 k, height, width;
|
|
|
984
|
|
|
985 /* In this example, "image" is a one-dimensional array of bytes */
|
|
|
986 png_byte image[height*width*bytes_per_pixel];
|
|
|
987
|
|
|
988 png_bytep row_pointers[height];
|
|
|
989
|
|
|
990 if (height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
|
|
|
991 png_error (png_ptr, "Image is too tall to process in memory");
|
|
|
992
|
|
|
993 /* Set up pointers into your "image" byte array */
|
|
|
994 for (k = 0; k < height; k++)
|
|
|
995 row_pointers[k] = image + k*width*bytes_per_pixel;
|
|
|
996
|
|
|
997 /* One of the following output methods is REQUIRED */
|
|
|
998
|
|
|
999 #ifdef entire /* Write out the entire image data in one call */
|
|
|
1000 png_write_image(png_ptr, row_pointers);
|
|
|
1001
|
|
|
1002 /* The other way to write the image - deal with interlacing */
|
|
|
1003
|
|
|
1004 #else no_entire /* Write out the image data by one or more scanlines */
|
|
|
1005
|
|
|
1006 /* The number of passes is either 1 for non-interlaced images,
|
|
|
1007 * or 7 for interlaced images.
|
|
|
1008 */
|
|
|
1009 for (pass = 0; pass < number_passes; pass++)
|
|
|
1010 {
|
|
|
1011 /* Write a few rows at a time. */
|
|
|
1012 png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows);
|
|
|
1013
|
|
|
1014 /* If you are only writing one row at a time, this works */
|
|
|
1015 for (y = 0; y < height; y++)
|
|
|
1016 png_write_rows(png_ptr, &row_pointers[y], 1);
|
|
|
1017 }
|
|
|
1018 #endif no_entire /* Use only one output method */
|
|
|
1019
|
|
|
1020 /* You can write optional chunks like tEXt, zTXt, and tIME at the end
|
|
|
1021 * as well. Shouldn't be necessary in 1.2.0 and up as all the public
|
|
|
1022 * chunks are supported and you can use png_set_unknown_chunks() to
|
|
|
1023 * register unknown chunks into the info structure to be written out.
|
|
|
1024 */
|
|
|
1025
|
|
|
1026 /* It is REQUIRED to call this to finish writing the rest of the file */
|
|
|
1027 png_write_end(png_ptr, info_ptr);
|
|
|
1028 #endif hilevel
|
|
|
1029
|
|
|
1030 /* If you png_malloced a palette, free it here (don't free info_ptr->palette,
|
|
|
1031 * as recommended in versions 1.0.5m and earlier of this example; if
|
|
|
1032 * libpng mallocs info_ptr->palette, libpng will free it). If you
|
|
|
1033 * allocated it with malloc() instead of png_malloc(), use free() instead
|
|
|
1034 * of png_free().
|
|
|
1035 */
|
|
|
1036 png_free(png_ptr, palette);
|
|
|
1037 palette = NULL;
|
|
|
1038
|
|
|
1039 /* Similarly, if you png_malloced any data that you passed in with
|
|
|
1040 * png_set_something(), such as a hist or trans array, free it here,
|
|
|
1041 * when you can be sure that libpng is through with it.
|
|
|
1042 */
|
|
|
1043 png_free(png_ptr, trans);
|
|
|
1044 trans = NULL;
|
|
|
1045 /* Whenever you use png_free() it is a good idea to set the pointer to
|
|
|
1046 * NULL in case your application inadvertently tries to png_free() it
|
|
|
1047 * again. When png_free() sees a NULL it returns without action, thus
|
|
|
1048 * avoiding the double-free security problem.
|
|
|
1049 */
|
|
|
1050
|
|
|
1051 /* Clean up after the write, and free any memory allocated */
|
|
|
1052 png_destroy_write_struct(&png_ptr, &info_ptr);
|
|
|
1053
|
|
|
1054 /* Close the file */
|
|
|
1055 fclose(fp);
|
|
|
1056
|
|
|
1057 /* That's it */
|
|
|
1058 return (OK);
|
|
|
1059 }
|
|
|
1060
|
|
|
1061 #endif /* if 0 */
|
