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2297
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1
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2 /* png.c - location for general purpose libpng functions
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3 *
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4 * Last changed in libpng 1.6.9 [February 6, 2014]
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5 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
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6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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8 *
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9 * This code is released under the libpng license.
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10 * For conditions of distribution and use, see the disclaimer
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11 * and license in png.h
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12 */
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13
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14 #include "pngpriv.h"
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15
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16 /* Generate a compiler error if there is an old png.h in the search path. */
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17 typedef png_libpng_version_1_6_10 Your_png_h_is_not_version_1_6_10;
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18
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19 /* Tells libpng that we have already handled the first "num_bytes" bytes
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20 * of the PNG file signature. If the PNG data is embedded into another
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21 * stream we can set num_bytes = 8 so that libpng will not attempt to read
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22 * or write any of the magic bytes before it starts on the IHDR.
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23 */
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24
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25 #ifdef PNG_READ_SUPPORTED
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26 void PNGAPI
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27 png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
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28 {
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29 png_debug(1, "in png_set_sig_bytes");
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30
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31 if (png_ptr == NULL)
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32 return;
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33
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34 if (num_bytes > 8)
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35 png_error(png_ptr, "Too many bytes for PNG signature");
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36
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37 png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
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38 }
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39
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40 /* Checks whether the supplied bytes match the PNG signature. We allow
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41 * checking less than the full 8-byte signature so that those apps that
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42 * already read the first few bytes of a file to determine the file type
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43 * can simply check the remaining bytes for extra assurance. Returns
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44 * an integer less than, equal to, or greater than zero if sig is found,
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45 * respectively, to be less than, to match, or be greater than the correct
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46 * PNG signature (this is the same behavior as strcmp, memcmp, etc).
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47 */
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48 int PNGAPI
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49 png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
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50 {
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51 png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
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52
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53 if (num_to_check > 8)
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54 num_to_check = 8;
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55
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56 else if (num_to_check < 1)
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57 return (-1);
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58
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59 if (start > 7)
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60 return (-1);
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61
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62 if (start + num_to_check > 8)
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63 num_to_check = 8 - start;
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64
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65 return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
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66 }
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67
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68 #endif /* PNG_READ_SUPPORTED */
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69
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70 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
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71 /* Function to allocate memory for zlib */
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72 PNG_FUNCTION(voidpf /* PRIVATE */,
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73 png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
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74 {
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75 png_alloc_size_t num_bytes = size;
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76
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77 if (png_ptr == NULL)
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78 return NULL;
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79
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80 if (items >= (~(png_alloc_size_t)0)/size)
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81 {
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82 png_warning (png_voidcast(png_structrp, png_ptr),
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83 "Potential overflow in png_zalloc()");
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84 return NULL;
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85 }
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86
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87 num_bytes *= items;
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88 return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
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89 }
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90
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91 /* Function to free memory for zlib */
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92 void /* PRIVATE */
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93 png_zfree(voidpf png_ptr, voidpf ptr)
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94 {
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95 png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
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96 }
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97
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98 /* Reset the CRC variable to 32 bits of 1's. Care must be taken
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99 * in case CRC is > 32 bits to leave the top bits 0.
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100 */
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101 void /* PRIVATE */
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102 png_reset_crc(png_structrp png_ptr)
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103 {
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104 /* The cast is safe because the crc is a 32 bit value. */
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105 png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
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106 }
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107
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108 /* Calculate the CRC over a section of data. We can only pass as
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109 * much data to this routine as the largest single buffer size. We
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110 * also check that this data will actually be used before going to the
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111 * trouble of calculating it.
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112 */
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113 void /* PRIVATE */
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114 png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
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115 {
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116 int need_crc = 1;
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117
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118 if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name))
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119 {
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120 if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
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121 (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
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122 need_crc = 0;
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123 }
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124
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125 else /* critical */
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126 {
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127 if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE)
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128 need_crc = 0;
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129 }
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130
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131 /* 'uLong' is defined in zlib.h as unsigned long; this means that on some
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132 * systems it is a 64 bit value. crc32, however, returns 32 bits so the
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133 * following cast is safe. 'uInt' may be no more than 16 bits, so it is
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134 * necessary to perform a loop here.
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135 */
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136 if (need_crc && length > 0)
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137 {
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138 uLong crc = png_ptr->crc; /* Should never issue a warning */
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139
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140 do
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141 {
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142 uInt safe_length = (uInt)length;
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143 if (safe_length == 0)
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144 safe_length = (uInt)-1; /* evil, but safe */
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145
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146 crc = crc32(crc, ptr, safe_length);
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147
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148 /* The following should never issue compiler warnings; if they do the
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149 * target system has characteristics that will probably violate other
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150 * assumptions within the libpng code.
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151 */
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152 ptr += safe_length;
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153 length -= safe_length;
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154 }
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155 while (length > 0);
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156
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157 /* And the following is always safe because the crc is only 32 bits. */
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158 png_ptr->crc = (png_uint_32)crc;
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159 }
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160 }
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161
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162 /* Check a user supplied version number, called from both read and write
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163 * functions that create a png_struct.
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164 */
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165 int
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166 png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
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167 {
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168 if (user_png_ver)
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169 {
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170 int i = 0;
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171
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172 do
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173 {
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174 if (user_png_ver[i] != png_libpng_ver[i])
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175 png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
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176 } while (png_libpng_ver[i++]);
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177 }
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178
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179 else
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180 png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
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181
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182 if (png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH)
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183 {
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184 /* Libpng 0.90 and later are binary incompatible with libpng 0.89, so
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185 * we must recompile any applications that use any older library version.
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186 * For versions after libpng 1.0, we will be compatible, so we need
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187 * only check the first and third digits (note that when we reach version
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188 * 1.10 we will need to check the fourth symbol, namely user_png_ver[3]).
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189 */
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190 if (user_png_ver == NULL || user_png_ver[0] != png_libpng_ver[0] ||
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191 (user_png_ver[0] == '1' && (user_png_ver[2] != png_libpng_ver[2] ||
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192 user_png_ver[3] != png_libpng_ver[3])) ||
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193 (user_png_ver[0] == '0' && user_png_ver[2] < '9'))
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194 {
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195 #ifdef PNG_WARNINGS_SUPPORTED
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196 size_t pos = 0;
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197 char m[128];
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198
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199 pos = png_safecat(m, (sizeof m), pos,
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200 "Application built with libpng-");
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201 pos = png_safecat(m, (sizeof m), pos, user_png_ver);
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202 pos = png_safecat(m, (sizeof m), pos, " but running with ");
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203 pos = png_safecat(m, (sizeof m), pos, png_libpng_ver);
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204 PNG_UNUSED(pos)
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205
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206 png_warning(png_ptr, m);
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207 #endif
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208
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209 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
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210 png_ptr->flags = 0;
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211 #endif
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212
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213 return 0;
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214 }
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215 }
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216
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217 /* Success return. */
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218 return 1;
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219 }
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220
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221 /* Generic function to create a png_struct for either read or write - this
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222 * contains the common initialization.
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223 */
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224 PNG_FUNCTION(png_structp /* PRIVATE */,
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225 png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
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226 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
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227 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
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228 {
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229 png_struct create_struct;
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230 # ifdef PNG_SETJMP_SUPPORTED
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231 jmp_buf create_jmp_buf;
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232 # endif
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233
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234 /* This temporary stack-allocated structure is used to provide a place to
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235 * build enough context to allow the user provided memory allocator (if any)
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236 * to be called.
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237 */
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238 memset(&create_struct, 0, (sizeof create_struct));
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239
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240 /* Added at libpng-1.2.6 */
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241 # ifdef PNG_USER_LIMITS_SUPPORTED
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242 create_struct.user_width_max = PNG_USER_WIDTH_MAX;
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243 create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
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244
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245 # ifdef PNG_USER_CHUNK_CACHE_MAX
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246 /* Added at libpng-1.2.43 and 1.4.0 */
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247 create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
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248 # endif
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249
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250 # ifdef PNG_USER_CHUNK_MALLOC_MAX
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251 /* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
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252 * in png_struct regardless.
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253 */
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254 create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
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255 # endif
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256 # endif
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257
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258 /* The following two API calls simply set fields in png_struct, so it is safe
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259 * to do them now even though error handling is not yet set up.
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260 */
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261 # ifdef PNG_USER_MEM_SUPPORTED
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262 png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
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263 # else
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264 PNG_UNUSED(mem_ptr)
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265 PNG_UNUSED(malloc_fn)
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266 PNG_UNUSED(free_fn)
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267 # endif
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268
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269 /* (*error_fn) can return control to the caller after the error_ptr is set,
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270 * this will result in a memory leak unless the error_fn does something
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271 * extremely sophisticated. The design lacks merit but is implicit in the
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272 * API.
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273 */
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274 png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
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275
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276 # ifdef PNG_SETJMP_SUPPORTED
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277 if (!setjmp(create_jmp_buf))
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278 {
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279 /* Temporarily fake out the longjmp information until we have
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280 * successfully completed this function. This only works if we have
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281 * setjmp() support compiled in, but it is safe - this stuff should
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282 * never happen.
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283 */
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284 create_struct.jmp_buf_ptr = &create_jmp_buf;
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285 create_struct.jmp_buf_size = 0; /*stack allocation*/
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286 create_struct.longjmp_fn = longjmp;
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287 # else
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288 {
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289 # endif
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290 /* Call the general version checker (shared with read and write code):
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291 */
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292 if (png_user_version_check(&create_struct, user_png_ver))
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293 {
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294 png_structrp png_ptr = png_voidcast(png_structrp,
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295 png_malloc_warn(&create_struct, (sizeof *png_ptr)));
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296
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297 if (png_ptr != NULL)
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298 {
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299 /* png_ptr->zstream holds a back-pointer to the png_struct, so
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300 * this can only be done now:
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301 */
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302 create_struct.zstream.zalloc = png_zalloc;
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303 create_struct.zstream.zfree = png_zfree;
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304 create_struct.zstream.opaque = png_ptr;
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305
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306 # ifdef PNG_SETJMP_SUPPORTED
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307 /* Eliminate the local error handling: */
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308 create_struct.jmp_buf_ptr = NULL;
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309 create_struct.jmp_buf_size = 0;
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310 create_struct.longjmp_fn = 0;
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311 # endif
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312
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313 *png_ptr = create_struct;
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314
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315 /* This is the successful return point */
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316 return png_ptr;
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317 }
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318 }
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319 }
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320
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321 /* A longjmp because of a bug in the application storage allocator or a
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322 * simple failure to allocate the png_struct.
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323 */
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324 return NULL;
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325 }
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326
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327 /* Allocate the memory for an info_struct for the application. */
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328 PNG_FUNCTION(png_infop,PNGAPI
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329 png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
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330 {
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331 png_inforp info_ptr;
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332
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333 png_debug(1, "in png_create_info_struct");
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334
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335 if (png_ptr == NULL)
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336 return NULL;
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337
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338 /* Use the internal API that does not (or at least should not) error out, so
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339 * that this call always returns ok. The application typically sets up the
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340 * error handling *after* creating the info_struct because this is the way it
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341 * has always been done in 'example.c'.
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342 */
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343 info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
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344 (sizeof *info_ptr)));
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345
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346 if (info_ptr != NULL)
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347 memset(info_ptr, 0, (sizeof *info_ptr));
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348
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349 return info_ptr;
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350 }
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351
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352 /* This function frees the memory associated with a single info struct.
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353 * Normally, one would use either png_destroy_read_struct() or
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354 * png_destroy_write_struct() to free an info struct, but this may be
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355 * useful for some applications. From libpng 1.6.0 this function is also used
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356 * internally to implement the png_info release part of the 'struct' destroy
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357 * APIs. This ensures that all possible approaches free the same data (all of
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358 * it).
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359 */
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360 void PNGAPI
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361 png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
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362 {
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363 png_inforp info_ptr = NULL;
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364
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365 png_debug(1, "in png_destroy_info_struct");
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366
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367 if (png_ptr == NULL)
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368 return;
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369
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370 if (info_ptr_ptr != NULL)
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371 info_ptr = *info_ptr_ptr;
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372
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373 if (info_ptr != NULL)
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374 {
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375 /* Do this first in case of an error below; if the app implements its own
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376 * memory management this can lead to png_free calling png_error, which
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377 * will abort this routine and return control to the app error handler.
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378 * An infinite loop may result if it then tries to free the same info
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379 * ptr.
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380 */
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381 *info_ptr_ptr = NULL;
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382
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383 png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
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384 memset(info_ptr, 0, (sizeof *info_ptr));
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385 png_free(png_ptr, info_ptr);
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386 }
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387 }
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388
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389 /* Initialize the info structure. This is now an internal function (0.89)
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390 * and applications using it are urged to use png_create_info_struct()
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391 * instead. Use deprecated in 1.6.0, internal use removed (used internally it
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392 * is just a memset).
|
|
|
393 *
|
|
|
394 * NOTE: it is almost inconceivable that this API is used because it bypasses
|
|
|
395 * the user-memory mechanism and the user error handling/warning mechanisms in
|
|
|
396 * those cases where it does anything other than a memset.
|
|
|
397 */
|
|
|
398 PNG_FUNCTION(void,PNGAPI
|
|
|
399 png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
|
|
|
400 PNG_DEPRECATED)
|
|
|
401 {
|
|
|
402 png_inforp info_ptr = *ptr_ptr;
|
|
|
403
|
|
|
404 png_debug(1, "in png_info_init_3");
|
|
|
405
|
|
|
406 if (info_ptr == NULL)
|
|
|
407 return;
|
|
|
408
|
|
|
409 if ((sizeof (png_info)) > png_info_struct_size)
|
|
|
410 {
|
|
|
411 *ptr_ptr = NULL;
|
|
|
412 /* The following line is why this API should not be used: */
|
|
|
413 free(info_ptr);
|
|
|
414 info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
|
|
|
415 (sizeof *info_ptr)));
|
|
|
416 *ptr_ptr = info_ptr;
|
|
|
417 }
|
|
|
418
|
|
|
419 /* Set everything to 0 */
|
|
|
420 memset(info_ptr, 0, (sizeof *info_ptr));
|
|
|
421 }
|
|
|
422
|
|
|
423 /* The following API is not called internally */
|
|
|
424 void PNGAPI
|
|
|
425 png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
|
|
|
426 int freer, png_uint_32 mask)
|
|
|
427 {
|
|
|
428 png_debug(1, "in png_data_freer");
|
|
|
429
|
|
|
430 if (png_ptr == NULL || info_ptr == NULL)
|
|
|
431 return;
|
|
|
432
|
|
|
433 if (freer == PNG_DESTROY_WILL_FREE_DATA)
|
|
|
434 info_ptr->free_me |= mask;
|
|
|
435
|
|
|
436 else if (freer == PNG_USER_WILL_FREE_DATA)
|
|
|
437 info_ptr->free_me &= ~mask;
|
|
|
438
|
|
|
439 else
|
|
|
440 png_error(png_ptr, "Unknown freer parameter in png_data_freer");
|
|
|
441 }
|
|
|
442
|
|
|
443 void PNGAPI
|
|
|
444 png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
|
|
|
445 int num)
|
|
|
446 {
|
|
|
447 png_debug(1, "in png_free_data");
|
|
|
448
|
|
|
449 if (png_ptr == NULL || info_ptr == NULL)
|
|
|
450 return;
|
|
|
451
|
|
|
452 #ifdef PNG_TEXT_SUPPORTED
|
|
|
453 /* Free text item num or (if num == -1) all text items */
|
|
|
454 if ((mask & PNG_FREE_TEXT) & info_ptr->free_me)
|
|
|
455 {
|
|
|
456 if (num != -1)
|
|
|
457 {
|
|
|
458 if (info_ptr->text && info_ptr->text[num].key)
|
|
|
459 {
|
|
|
460 png_free(png_ptr, info_ptr->text[num].key);
|
|
|
461 info_ptr->text[num].key = NULL;
|
|
|
462 }
|
|
|
463 }
|
|
|
464
|
|
|
465 else
|
|
|
466 {
|
|
|
467 int i;
|
|
|
468 for (i = 0; i < info_ptr->num_text; i++)
|
|
|
469 png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i);
|
|
|
470 png_free(png_ptr, info_ptr->text);
|
|
|
471 info_ptr->text = NULL;
|
|
|
472 info_ptr->num_text=0;
|
|
|
473 }
|
|
|
474 }
|
|
|
475 #endif
|
|
|
476
|
|
|
477 #ifdef PNG_tRNS_SUPPORTED
|
|
|
478 /* Free any tRNS entry */
|
|
|
479 if ((mask & PNG_FREE_TRNS) & info_ptr->free_me)
|
|
|
480 {
|
|
|
481 png_free(png_ptr, info_ptr->trans_alpha);
|
|
|
482 info_ptr->trans_alpha = NULL;
|
|
|
483 info_ptr->valid &= ~PNG_INFO_tRNS;
|
|
|
484 }
|
|
|
485 #endif
|
|
|
486
|
|
|
487 #ifdef PNG_sCAL_SUPPORTED
|
|
|
488 /* Free any sCAL entry */
|
|
|
489 if ((mask & PNG_FREE_SCAL) & info_ptr->free_me)
|
|
|
490 {
|
|
|
491 png_free(png_ptr, info_ptr->scal_s_width);
|
|
|
492 png_free(png_ptr, info_ptr->scal_s_height);
|
|
|
493 info_ptr->scal_s_width = NULL;
|
|
|
494 info_ptr->scal_s_height = NULL;
|
|
|
495 info_ptr->valid &= ~PNG_INFO_sCAL;
|
|
|
496 }
|
|
|
497 #endif
|
|
|
498
|
|
|
499 #ifdef PNG_pCAL_SUPPORTED
|
|
|
500 /* Free any pCAL entry */
|
|
|
501 if ((mask & PNG_FREE_PCAL) & info_ptr->free_me)
|
|
|
502 {
|
|
|
503 png_free(png_ptr, info_ptr->pcal_purpose);
|
|
|
504 png_free(png_ptr, info_ptr->pcal_units);
|
|
|
505 info_ptr->pcal_purpose = NULL;
|
|
|
506 info_ptr->pcal_units = NULL;
|
|
|
507 if (info_ptr->pcal_params != NULL)
|
|
|
508 {
|
|
|
509 unsigned int i;
|
|
|
510 for (i = 0; i < info_ptr->pcal_nparams; i++)
|
|
|
511 {
|
|
|
512 png_free(png_ptr, info_ptr->pcal_params[i]);
|
|
|
513 info_ptr->pcal_params[i] = NULL;
|
|
|
514 }
|
|
|
515 png_free(png_ptr, info_ptr->pcal_params);
|
|
|
516 info_ptr->pcal_params = NULL;
|
|
|
517 }
|
|
|
518 info_ptr->valid &= ~PNG_INFO_pCAL;
|
|
|
519 }
|
|
|
520 #endif
|
|
|
521
|
|
|
522 #ifdef PNG_iCCP_SUPPORTED
|
|
|
523 /* Free any profile entry */
|
|
|
524 if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
|
|
|
525 {
|
|
|
526 png_free(png_ptr, info_ptr->iccp_name);
|
|
|
527 png_free(png_ptr, info_ptr->iccp_profile);
|
|
|
528 info_ptr->iccp_name = NULL;
|
|
|
529 info_ptr->iccp_profile = NULL;
|
|
|
530 info_ptr->valid &= ~PNG_INFO_iCCP;
|
|
|
531 }
|
|
|
532 #endif
|
|
|
533
|
|
|
534 #ifdef PNG_sPLT_SUPPORTED
|
|
|
535 /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
|
|
|
536 if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
|
|
|
537 {
|
|
|
538 if (num != -1)
|
|
|
539 {
|
|
|
540 if (info_ptr->splt_palettes)
|
|
|
541 {
|
|
|
542 png_free(png_ptr, info_ptr->splt_palettes[num].name);
|
|
|
543 png_free(png_ptr, info_ptr->splt_palettes[num].entries);
|
|
|
544 info_ptr->splt_palettes[num].name = NULL;
|
|
|
545 info_ptr->splt_palettes[num].entries = NULL;
|
|
|
546 }
|
|
|
547 }
|
|
|
548
|
|
|
549 else
|
|
|
550 {
|
|
|
551 if (info_ptr->splt_palettes_num)
|
|
|
552 {
|
|
|
553 int i;
|
|
|
554 for (i = 0; i < info_ptr->splt_palettes_num; i++)
|
|
|
555 png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, (int)i);
|
|
|
556
|
|
|
557 png_free(png_ptr, info_ptr->splt_palettes);
|
|
|
558 info_ptr->splt_palettes = NULL;
|
|
|
559 info_ptr->splt_palettes_num = 0;
|
|
|
560 }
|
|
|
561 info_ptr->valid &= ~PNG_INFO_sPLT;
|
|
|
562 }
|
|
|
563 }
|
|
|
564 #endif
|
|
|
565
|
|
|
566 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
|
|
|
567 if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
|
|
|
568 {
|
|
|
569 if (num != -1)
|
|
|
570 {
|
|
|
571 if (info_ptr->unknown_chunks)
|
|
|
572 {
|
|
|
573 png_free(png_ptr, info_ptr->unknown_chunks[num].data);
|
|
|
574 info_ptr->unknown_chunks[num].data = NULL;
|
|
|
575 }
|
|
|
576 }
|
|
|
577
|
|
|
578 else
|
|
|
579 {
|
|
|
580 int i;
|
|
|
581
|
|
|
582 if (info_ptr->unknown_chunks_num)
|
|
|
583 {
|
|
|
584 for (i = 0; i < info_ptr->unknown_chunks_num; i++)
|
|
|
585 png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, (int)i);
|
|
|
586
|
|
|
587 png_free(png_ptr, info_ptr->unknown_chunks);
|
|
|
588 info_ptr->unknown_chunks = NULL;
|
|
|
589 info_ptr->unknown_chunks_num = 0;
|
|
|
590 }
|
|
|
591 }
|
|
|
592 }
|
|
|
593 #endif
|
|
|
594
|
|
|
595 #ifdef PNG_hIST_SUPPORTED
|
|
|
596 /* Free any hIST entry */
|
|
|
597 if ((mask & PNG_FREE_HIST) & info_ptr->free_me)
|
|
|
598 {
|
|
|
599 png_free(png_ptr, info_ptr->hist);
|
|
|
600 info_ptr->hist = NULL;
|
|
|
601 info_ptr->valid &= ~PNG_INFO_hIST;
|
|
|
602 }
|
|
|
603 #endif
|
|
|
604
|
|
|
605 /* Free any PLTE entry that was internally allocated */
|
|
|
606 if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
|
|
|
607 {
|
|
|
608 png_free(png_ptr, info_ptr->palette);
|
|
|
609 info_ptr->palette = NULL;
|
|
|
610 info_ptr->valid &= ~PNG_INFO_PLTE;
|
|
|
611 info_ptr->num_palette = 0;
|
|
|
612 }
|
|
|
613
|
|
|
614 #ifdef PNG_INFO_IMAGE_SUPPORTED
|
|
|
615 /* Free any image bits attached to the info structure */
|
|
|
616 if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
|
|
|
617 {
|
|
|
618 if (info_ptr->row_pointers)
|
|
|
619 {
|
|
|
620 png_uint_32 row;
|
|
|
621 for (row = 0; row < info_ptr->height; row++)
|
|
|
622 {
|
|
|
623 png_free(png_ptr, info_ptr->row_pointers[row]);
|
|
|
624 info_ptr->row_pointers[row] = NULL;
|
|
|
625 }
|
|
|
626 png_free(png_ptr, info_ptr->row_pointers);
|
|
|
627 info_ptr->row_pointers = NULL;
|
|
|
628 }
|
|
|
629 info_ptr->valid &= ~PNG_INFO_IDAT;
|
|
|
630 }
|
|
|
631 #endif
|
|
|
632
|
|
|
633 if (num != -1)
|
|
|
634 mask &= ~PNG_FREE_MUL;
|
|
|
635
|
|
|
636 info_ptr->free_me &= ~mask;
|
|
|
637 }
|
|
|
638 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
|
|
639
|
|
|
640 /* This function returns a pointer to the io_ptr associated with the user
|
|
|
641 * functions. The application should free any memory associated with this
|
|
|
642 * pointer before png_write_destroy() or png_read_destroy() are called.
|
|
|
643 */
|
|
|
644 png_voidp PNGAPI
|
|
|
645 png_get_io_ptr(png_const_structrp png_ptr)
|
|
|
646 {
|
|
|
647 if (png_ptr == NULL)
|
|
|
648 return (NULL);
|
|
|
649
|
|
|
650 return (png_ptr->io_ptr);
|
|
|
651 }
|
|
|
652
|
|
|
653 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
|
|
|
654 # ifdef PNG_STDIO_SUPPORTED
|
|
|
655 /* Initialize the default input/output functions for the PNG file. If you
|
|
|
656 * use your own read or write routines, you can call either png_set_read_fn()
|
|
|
657 * or png_set_write_fn() instead of png_init_io(). If you have defined
|
|
|
658 * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
|
|
|
659 * function of your own because "FILE *" isn't necessarily available.
|
|
|
660 */
|
|
|
661 void PNGAPI
|
|
|
662 png_init_io(png_structrp png_ptr, png_FILE_p fp)
|
|
|
663 {
|
|
|
664 png_debug(1, "in png_init_io");
|
|
|
665
|
|
|
666 if (png_ptr == NULL)
|
|
|
667 return;
|
|
|
668
|
|
|
669 png_ptr->io_ptr = (png_voidp)fp;
|
|
|
670 }
|
|
|
671 # endif
|
|
|
672
|
|
|
673 #ifdef PNG_SAVE_INT_32_SUPPORTED
|
|
|
674 /* The png_save_int_32 function assumes integers are stored in two's
|
|
|
675 * complement format. If this isn't the case, then this routine needs to
|
|
|
676 * be modified to write data in two's complement format. Note that,
|
|
|
677 * the following works correctly even if png_int_32 has more than 32 bits
|
|
|
678 * (compare the more complex code required on read for sign extension.)
|
|
|
679 */
|
|
|
680 void PNGAPI
|
|
|
681 png_save_int_32(png_bytep buf, png_int_32 i)
|
|
|
682 {
|
|
|
683 buf[0] = (png_byte)((i >> 24) & 0xff);
|
|
|
684 buf[1] = (png_byte)((i >> 16) & 0xff);
|
|
|
685 buf[2] = (png_byte)((i >> 8) & 0xff);
|
|
|
686 buf[3] = (png_byte)(i & 0xff);
|
|
|
687 }
|
|
|
688 #endif
|
|
|
689
|
|
|
690 # ifdef PNG_TIME_RFC1123_SUPPORTED
|
|
|
691 /* Convert the supplied time into an RFC 1123 string suitable for use in
|
|
|
692 * a "Creation Time" or other text-based time string.
|
|
|
693 */
|
|
|
694 int PNGAPI
|
|
|
695 png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
|
|
|
696 {
|
|
|
697 static PNG_CONST char short_months[12][4] =
|
|
|
698 {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
|
|
|
699 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
|
|
|
700
|
|
|
701 if (out == NULL)
|
|
|
702 return 0;
|
|
|
703
|
|
|
704 if (ptime->year > 9999 /* RFC1123 limitation */ ||
|
|
|
705 ptime->month == 0 || ptime->month > 12 ||
|
|
|
706 ptime->day == 0 || ptime->day > 31 ||
|
|
|
707 ptime->hour > 23 || ptime->minute > 59 ||
|
|
|
708 ptime->second > 60)
|
|
|
709 return 0;
|
|
|
710
|
|
|
711 {
|
|
|
712 size_t pos = 0;
|
|
|
713 char number_buf[5]; /* enough for a four-digit year */
|
|
|
714
|
|
|
715 # define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
|
|
|
716 # define APPEND_NUMBER(format, value)\
|
|
|
717 APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
|
|
|
718 # define APPEND(ch) if (pos < 28) out[pos++] = (ch)
|
|
|
719
|
|
|
720 APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
|
|
|
721 APPEND(' ');
|
|
|
722 APPEND_STRING(short_months[(ptime->month - 1)]);
|
|
|
723 APPEND(' ');
|
|
|
724 APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
|
|
|
725 APPEND(' ');
|
|
|
726 APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
|
|
|
727 APPEND(':');
|
|
|
728 APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
|
|
|
729 APPEND(':');
|
|
|
730 APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
|
|
|
731 APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
|
|
|
732
|
|
|
733 # undef APPEND
|
|
|
734 # undef APPEND_NUMBER
|
|
|
735 # undef APPEND_STRING
|
|
|
736 }
|
|
|
737
|
|
|
738 return 1;
|
|
|
739 }
|
|
|
740
|
|
|
741 # if PNG_LIBPNG_VER < 10700
|
|
|
742 /* To do: remove the following from libpng-1.7 */
|
|
|
743 /* Original API that uses a private buffer in png_struct.
|
|
|
744 * Deprecated because it causes png_struct to carry a spurious temporary
|
|
|
745 * buffer (png_struct::time_buffer), better to have the caller pass this in.
|
|
|
746 */
|
|
|
747 png_const_charp PNGAPI
|
|
|
748 png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
|
|
|
749 {
|
|
|
750 if (png_ptr != NULL)
|
|
|
751 {
|
|
|
752 /* The only failure above if png_ptr != NULL is from an invalid ptime */
|
|
|
753 if (!png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime))
|
|
|
754 png_warning(png_ptr, "Ignoring invalid time value");
|
|
|
755
|
|
|
756 else
|
|
|
757 return png_ptr->time_buffer;
|
|
|
758 }
|
|
|
759
|
|
|
760 return NULL;
|
|
|
761 }
|
|
|
762 # endif
|
|
|
763 # endif /* PNG_TIME_RFC1123_SUPPORTED */
|
|
|
764
|
|
|
765 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
|
|
766
|
|
|
767 png_const_charp PNGAPI
|
|
|
768 png_get_copyright(png_const_structrp png_ptr)
|
|
|
769 {
|
|
|
770 PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
|
|
771 #ifdef PNG_STRING_COPYRIGHT
|
|
|
772 return PNG_STRING_COPYRIGHT
|
|
|
773 #else
|
|
|
774 # ifdef __STDC__
|
|
|
775 return PNG_STRING_NEWLINE \
|
|
|
776 "libpng version 1.6.10 - March 6, 2014" PNG_STRING_NEWLINE \
|
|
|
777 "Copyright (c) 1998-2014 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
|
|
|
778 "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
|
|
|
779 "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
|
|
|
780 PNG_STRING_NEWLINE;
|
|
|
781 # else
|
|
|
782 return "libpng version 1.6.10 - March 6, 2014\
|
|
|
783 Copyright (c) 1998-2014 Glenn Randers-Pehrson\
|
|
|
784 Copyright (c) 1996-1997 Andreas Dilger\
|
|
|
785 Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
|
|
|
786 # endif
|
|
|
787 #endif
|
|
|
788 }
|
|
|
789
|
|
|
790 /* The following return the library version as a short string in the
|
|
|
791 * format 1.0.0 through 99.99.99zz. To get the version of *.h files
|
|
|
792 * used with your application, print out PNG_LIBPNG_VER_STRING, which
|
|
|
793 * is defined in png.h.
|
|
|
794 * Note: now there is no difference between png_get_libpng_ver() and
|
|
|
795 * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
|
|
|
796 * it is guaranteed that png.c uses the correct version of png.h.
|
|
|
797 */
|
|
|
798 png_const_charp PNGAPI
|
|
|
799 png_get_libpng_ver(png_const_structrp png_ptr)
|
|
|
800 {
|
|
|
801 /* Version of *.c files used when building libpng */
|
|
|
802 return png_get_header_ver(png_ptr);
|
|
|
803 }
|
|
|
804
|
|
|
805 png_const_charp PNGAPI
|
|
|
806 png_get_header_ver(png_const_structrp png_ptr)
|
|
|
807 {
|
|
|
808 /* Version of *.h files used when building libpng */
|
|
|
809 PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
|
|
810 return PNG_LIBPNG_VER_STRING;
|
|
|
811 }
|
|
|
812
|
|
|
813 png_const_charp PNGAPI
|
|
|
814 png_get_header_version(png_const_structrp png_ptr)
|
|
|
815 {
|
|
|
816 /* Returns longer string containing both version and date */
|
|
|
817 PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
|
|
|
818 #ifdef __STDC__
|
|
|
819 return PNG_HEADER_VERSION_STRING
|
|
|
820 # ifndef PNG_READ_SUPPORTED
|
|
|
821 " (NO READ SUPPORT)"
|
|
|
822 # endif
|
|
|
823 PNG_STRING_NEWLINE;
|
|
|
824 #else
|
|
|
825 return PNG_HEADER_VERSION_STRING;
|
|
|
826 #endif
|
|
|
827 }
|
|
|
828
|
|
|
829 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
|
|
|
830 /* NOTE: this routine is not used internally! */
|
|
|
831 /* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
|
|
|
832 * large of png_color. This lets grayscale images be treated as
|
|
|
833 * paletted. Most useful for gamma correction and simplification
|
|
|
834 * of code. This API is not used internally.
|
|
|
835 */
|
|
|
836 void PNGAPI
|
|
|
837 png_build_grayscale_palette(int bit_depth, png_colorp palette)
|
|
|
838 {
|
|
|
839 int num_palette;
|
|
|
840 int color_inc;
|
|
|
841 int i;
|
|
|
842 int v;
|
|
|
843
|
|
|
844 png_debug(1, "in png_do_build_grayscale_palette");
|
|
|
845
|
|
|
846 if (palette == NULL)
|
|
|
847 return;
|
|
|
848
|
|
|
849 switch (bit_depth)
|
|
|
850 {
|
|
|
851 case 1:
|
|
|
852 num_palette = 2;
|
|
|
853 color_inc = 0xff;
|
|
|
854 break;
|
|
|
855
|
|
|
856 case 2:
|
|
|
857 num_palette = 4;
|
|
|
858 color_inc = 0x55;
|
|
|
859 break;
|
|
|
860
|
|
|
861 case 4:
|
|
|
862 num_palette = 16;
|
|
|
863 color_inc = 0x11;
|
|
|
864 break;
|
|
|
865
|
|
|
866 case 8:
|
|
|
867 num_palette = 256;
|
|
|
868 color_inc = 1;
|
|
|
869 break;
|
|
|
870
|
|
|
871 default:
|
|
|
872 num_palette = 0;
|
|
|
873 color_inc = 0;
|
|
|
874 break;
|
|
|
875 }
|
|
|
876
|
|
|
877 for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
|
|
|
878 {
|
|
|
879 palette[i].red = (png_byte)v;
|
|
|
880 palette[i].green = (png_byte)v;
|
|
|
881 palette[i].blue = (png_byte)v;
|
|
|
882 }
|
|
|
883 }
|
|
|
884 #endif
|
|
|
885
|
|
|
886 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
|
|
|
887 int PNGAPI
|
|
|
888 png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
|
|
|
889 {
|
|
|
890 /* Check chunk_name and return "keep" value if it's on the list, else 0 */
|
|
|
891 png_const_bytep p, p_end;
|
|
|
892
|
|
|
893 if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
|
|
|
894 return PNG_HANDLE_CHUNK_AS_DEFAULT;
|
|
|
895
|
|
|
896 p_end = png_ptr->chunk_list;
|
|
|
897 p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
|
|
|
898
|
|
|
899 /* The code is the fifth byte after each four byte string. Historically this
|
|
|
900 * code was always searched from the end of the list, this is no longer
|
|
|
901 * necessary because the 'set' routine handles duplicate entries correcty.
|
|
|
902 */
|
|
|
903 do /* num_chunk_list > 0, so at least one */
|
|
|
904 {
|
|
|
905 p -= 5;
|
|
|
906
|
|
|
907 if (!memcmp(chunk_name, p, 4))
|
|
|
908 return p[4];
|
|
|
909 }
|
|
|
910 while (p > p_end);
|
|
|
911
|
|
|
912 /* This means that known chunks should be processed and unknown chunks should
|
|
|
913 * be handled according to the value of png_ptr->unknown_default; this can be
|
|
|
914 * confusing because, as a result, there are two levels of defaulting for
|
|
|
915 * unknown chunks.
|
|
|
916 */
|
|
|
917 return PNG_HANDLE_CHUNK_AS_DEFAULT;
|
|
|
918 }
|
|
|
919
|
|
|
920 #if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
|
|
|
921 defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
|
|
|
922 int /* PRIVATE */
|
|
|
923 png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
|
|
|
924 {
|
|
|
925 png_byte chunk_string[5];
|
|
|
926
|
|
|
927 PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
|
|
|
928 return png_handle_as_unknown(png_ptr, chunk_string);
|
|
|
929 }
|
|
|
930 #endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
|
|
|
931 #endif /* SET_UNKNOWN_CHUNKS */
|
|
|
932
|
|
|
933 #ifdef PNG_READ_SUPPORTED
|
|
|
934 /* This function, added to libpng-1.0.6g, is untested. */
|
|
|
935 int PNGAPI
|
|
|
936 png_reset_zstream(png_structrp png_ptr)
|
|
|
937 {
|
|
|
938 if (png_ptr == NULL)
|
|
|
939 return Z_STREAM_ERROR;
|
|
|
940
|
|
|
941 /* WARNING: this resets the window bits to the maximum! */
|
|
|
942 return (inflateReset(&png_ptr->zstream));
|
|
|
943 }
|
|
|
944 #endif /* PNG_READ_SUPPORTED */
|
|
|
945
|
|
|
946 /* This function was added to libpng-1.0.7 */
|
|
|
947 png_uint_32 PNGAPI
|
|
|
948 png_access_version_number(void)
|
|
|
949 {
|
|
|
950 /* Version of *.c files used when building libpng */
|
|
|
951 return((png_uint_32)PNG_LIBPNG_VER);
|
|
|
952 }
|
|
|
953
|
|
|
954
|
|
|
955
|
|
|
956 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
|
|
|
957 /* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
|
|
|
958 * If it doesn't 'ret' is used to set it to something appropriate, even in cases
|
|
|
959 * like Z_OK or Z_STREAM_END where the error code is apparently a success code.
|
|
|
960 */
|
|
|
961 void /* PRIVATE */
|
|
|
962 png_zstream_error(png_structrp png_ptr, int ret)
|
|
|
963 {
|
|
|
964 /* Translate 'ret' into an appropriate error string, priority is given to the
|
|
|
965 * one in zstream if set. This always returns a string, even in cases like
|
|
|
966 * Z_OK or Z_STREAM_END where the error code is a success code.
|
|
|
967 */
|
|
|
968 if (png_ptr->zstream.msg == NULL) switch (ret)
|
|
|
969 {
|
|
|
970 default:
|
|
|
971 case Z_OK:
|
|
|
972 png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
|
|
|
973 break;
|
|
|
974
|
|
|
975 case Z_STREAM_END:
|
|
|
976 /* Normal exit */
|
|
|
977 png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
|
|
|
978 break;
|
|
|
979
|
|
|
980 case Z_NEED_DICT:
|
|
|
981 /* This means the deflate stream did not have a dictionary; this
|
|
|
982 * indicates a bogus PNG.
|
|
|
983 */
|
|
|
984 png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
|
|
|
985 break;
|
|
|
986
|
|
|
987 case Z_ERRNO:
|
|
|
988 /* gz APIs only: should not happen */
|
|
|
989 png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
|
|
|
990 break;
|
|
|
991
|
|
|
992 case Z_STREAM_ERROR:
|
|
|
993 /* internal libpng error */
|
|
|
994 png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
|
|
|
995 break;
|
|
|
996
|
|
|
997 case Z_DATA_ERROR:
|
|
|
998 png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
|
|
|
999 break;
|
|
|
1000
|
|
|
1001 case Z_MEM_ERROR:
|
|
|
1002 png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
|
|
|
1003 break;
|
|
|
1004
|
|
|
1005 case Z_BUF_ERROR:
|
|
|
1006 /* End of input or output; not a problem if the caller is doing
|
|
|
1007 * incremental read or write.
|
|
|
1008 */
|
|
|
1009 png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
|
|
|
1010 break;
|
|
|
1011
|
|
|
1012 case Z_VERSION_ERROR:
|
|
|
1013 png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
|
|
|
1014 break;
|
|
|
1015
|
|
|
1016 case PNG_UNEXPECTED_ZLIB_RETURN:
|
|
|
1017 /* Compile errors here mean that zlib now uses the value co-opted in
|
|
|
1018 * pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
|
|
|
1019 * and change pngpriv.h. Note that this message is "... return",
|
|
|
1020 * whereas the default/Z_OK one is "... return code".
|
|
|
1021 */
|
|
|
1022 png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
|
|
|
1023 break;
|
|
|
1024 }
|
|
|
1025 }
|
|
|
1026
|
|
|
1027 /* png_convert_size: a PNGAPI but no longer in png.h, so deleted
|
|
|
1028 * at libpng 1.5.5!
|
|
|
1029 */
|
|
|
1030
|
|
|
1031 /* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
|
|
|
1032 #ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
|
|
|
1033 static int
|
|
|
1034 png_colorspace_check_gamma(png_const_structrp png_ptr,
|
|
|
1035 png_colorspacerp colorspace, png_fixed_point gAMA, int from)
|
|
|
1036 /* This is called to check a new gamma value against an existing one. The
|
|
|
1037 * routine returns false if the new gamma value should not be written.
|
|
|
1038 *
|
|
|
1039 * 'from' says where the new gamma value comes from:
|
|
|
1040 *
|
|
|
1041 * 0: the new gamma value is the libpng estimate for an ICC profile
|
|
|
1042 * 1: the new gamma value comes from a gAMA chunk
|
|
|
1043 * 2: the new gamma value comes from an sRGB chunk
|
|
|
1044 */
|
|
|
1045 {
|
|
|
1046 png_fixed_point gtest;
|
|
|
1047
|
|
|
1048 if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
|
|
|
1049 (!png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) ||
|
|
|
1050 png_gamma_significant(gtest)))
|
|
|
1051 {
|
|
|
1052 /* Either this is an sRGB image, in which case the calculated gamma
|
|
|
1053 * approximation should match, or this is an image with a profile and the
|
|
|
1054 * value libpng calculates for the gamma of the profile does not match the
|
|
|
1055 * value recorded in the file. The former, sRGB, case is an error, the
|
|
|
1056 * latter is just a warning.
|
|
|
1057 */
|
|
|
1058 if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
|
|
|
1059 {
|
|
|
1060 png_chunk_report(png_ptr, "gamma value does not match sRGB",
|
|
|
1061 PNG_CHUNK_ERROR);
|
|
|
1062 /* Do not overwrite an sRGB value */
|
|
|
1063 return from == 2;
|
|
|
1064 }
|
|
|
1065
|
|
|
1066 else /* sRGB tag not involved */
|
|
|
1067 {
|
|
|
1068 png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
|
|
|
1069 PNG_CHUNK_WARNING);
|
|
|
1070 return from == 1;
|
|
|
1071 }
|
|
|
1072 }
|
|
|
1073
|
|
|
1074 return 1;
|
|
|
1075 }
|
|
|
1076
|
|
|
1077 void /* PRIVATE */
|
|
|
1078 png_colorspace_set_gamma(png_const_structrp png_ptr,
|
|
|
1079 png_colorspacerp colorspace, png_fixed_point gAMA)
|
|
|
1080 {
|
|
|
1081 /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
|
|
|
1082 * occur. Since the fixed point representation is assymetrical it is
|
|
|
1083 * possible for 1/gamma to overflow the limit of 21474 and this means the
|
|
|
1084 * gamma value must be at least 5/100000 and hence at most 20000.0. For
|
|
|
1085 * safety the limits here are a little narrower. The values are 0.00016 to
|
|
|
1086 * 6250.0, which are truly ridiculous gamma values (and will produce
|
|
|
1087 * displays that are all black or all white.)
|
|
|
1088 *
|
|
|
1089 * In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
|
|
|
1090 * handling code, which only required the value to be >0.
|
|
|
1091 */
|
|
|
1092 png_const_charp errmsg;
|
|
|
1093
|
|
|
1094 if (gAMA < 16 || gAMA > 625000000)
|
|
|
1095 errmsg = "gamma value out of range";
|
|
|
1096
|
|
|
1097 # ifdef PNG_READ_gAMA_SUPPORTED
|
|
|
1098 /* Allow the application to set the gamma value more than once */
|
|
|
1099 else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
|
|
|
1100 (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
|
|
|
1101 errmsg = "duplicate";
|
|
|
1102 # endif
|
|
|
1103
|
|
|
1104 /* Do nothing if the colorspace is already invalid */
|
|
|
1105 else if (colorspace->flags & PNG_COLORSPACE_INVALID)
|
|
|
1106 return;
|
|
|
1107
|
|
|
1108 else
|
|
|
1109 {
|
|
|
1110 if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA, 1/*from gAMA*/))
|
|
|
1111 {
|
|
|
1112 /* Store this gamma value. */
|
|
|
1113 colorspace->gamma = gAMA;
|
|
|
1114 colorspace->flags |=
|
|
|
1115 (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
|
|
|
1116 }
|
|
|
1117
|
|
|
1118 /* At present if the check_gamma test fails the gamma of the colorspace is
|
|
|
1119 * not updated however the colorspace is not invalidated. This
|
|
|
1120 * corresponds to the case where the existing gamma comes from an sRGB
|
|
|
1121 * chunk or profile. An error message has already been output.
|
|
|
1122 */
|
|
|
1123 return;
|
|
|
1124 }
|
|
|
1125
|
|
|
1126 /* Error exit - errmsg has been set. */
|
|
|
1127 colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
1128 png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
|
|
|
1129 }
|
|
|
1130
|
|
|
1131 void /* PRIVATE */
|
|
|
1132 png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
|
|
|
1133 {
|
|
|
1134 if (info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID)
|
|
|
1135 {
|
|
|
1136 /* Everything is invalid */
|
|
|
1137 info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
|
|
|
1138 PNG_INFO_iCCP);
|
|
|
1139
|
|
|
1140 # ifdef PNG_COLORSPACE_SUPPORTED
|
|
|
1141 /* Clean up the iCCP profile now if it won't be used. */
|
|
|
1142 png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
|
|
|
1143 # else
|
|
|
1144 PNG_UNUSED(png_ptr)
|
|
|
1145 # endif
|
|
|
1146 }
|
|
|
1147
|
|
|
1148 else
|
|
|
1149 {
|
|
|
1150 # ifdef PNG_COLORSPACE_SUPPORTED
|
|
|
1151 /* Leave the INFO_iCCP flag set if the pngset.c code has already set
|
|
|
1152 * it; this allows a PNG to contain a profile which matches sRGB and
|
|
|
1153 * yet still have that profile retrievable by the application.
|
|
|
1154 */
|
|
|
1155 if (info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB)
|
|
|
1156 info_ptr->valid |= PNG_INFO_sRGB;
|
|
|
1157
|
|
|
1158 else
|
|
|
1159 info_ptr->valid &= ~PNG_INFO_sRGB;
|
|
|
1160
|
|
|
1161 if (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS)
|
|
|
1162 info_ptr->valid |= PNG_INFO_cHRM;
|
|
|
1163
|
|
|
1164 else
|
|
|
1165 info_ptr->valid &= ~PNG_INFO_cHRM;
|
|
|
1166 # endif
|
|
|
1167
|
|
|
1168 if (info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA)
|
|
|
1169 info_ptr->valid |= PNG_INFO_gAMA;
|
|
|
1170
|
|
|
1171 else
|
|
|
1172 info_ptr->valid &= ~PNG_INFO_gAMA;
|
|
|
1173 }
|
|
|
1174 }
|
|
|
1175
|
|
|
1176 #ifdef PNG_READ_SUPPORTED
|
|
|
1177 void /* PRIVATE */
|
|
|
1178 png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
|
|
|
1179 {
|
|
|
1180 if (info_ptr == NULL) /* reduce code size; check here not in the caller */
|
|
|
1181 return;
|
|
|
1182
|
|
|
1183 info_ptr->colorspace = png_ptr->colorspace;
|
|
|
1184 png_colorspace_sync_info(png_ptr, info_ptr);
|
|
|
1185 }
|
|
|
1186 #endif
|
|
|
1187 #endif
|
|
|
1188
|
|
|
1189 #ifdef PNG_COLORSPACE_SUPPORTED
|
|
|
1190 /* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
|
|
|
1191 * cHRM, as opposed to using chromaticities. These internal APIs return
|
|
|
1192 * non-zero on a parameter error. The X, Y and Z values are required to be
|
|
|
1193 * positive and less than 1.0.
|
|
|
1194 */
|
|
|
1195 static int
|
|
|
1196 png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
|
|
|
1197 {
|
|
|
1198 png_int_32 d, dwhite, whiteX, whiteY;
|
|
|
1199
|
|
|
1200 d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
|
|
|
1201 if (!png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d)) return 1;
|
|
|
1202 if (!png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d)) return 1;
|
|
|
1203 dwhite = d;
|
|
|
1204 whiteX = XYZ->red_X;
|
|
|
1205 whiteY = XYZ->red_Y;
|
|
|
1206
|
|
|
1207 d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
|
|
|
1208 if (!png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d)) return 1;
|
|
|
1209 if (!png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d)) return 1;
|
|
|
1210 dwhite += d;
|
|
|
1211 whiteX += XYZ->green_X;
|
|
|
1212 whiteY += XYZ->green_Y;
|
|
|
1213
|
|
|
1214 d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
|
|
|
1215 if (!png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d)) return 1;
|
|
|
1216 if (!png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d)) return 1;
|
|
|
1217 dwhite += d;
|
|
|
1218 whiteX += XYZ->blue_X;
|
|
|
1219 whiteY += XYZ->blue_Y;
|
|
|
1220
|
|
|
1221 /* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
|
|
|
1222 * thus:
|
|
|
1223 */
|
|
|
1224 if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1;
|
|
|
1225 if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1;
|
|
|
1226
|
|
|
1227 return 0;
|
|
|
1228 }
|
|
|
1229
|
|
|
1230 static int
|
|
|
1231 png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
|
|
|
1232 {
|
|
|
1233 png_fixed_point red_inverse, green_inverse, blue_scale;
|
|
|
1234 png_fixed_point left, right, denominator;
|
|
|
1235
|
|
|
1236 /* Check xy and, implicitly, z. Note that wide gamut color spaces typically
|
|
|
1237 * have end points with 0 tristimulus values (these are impossible end
|
|
|
1238 * points, but they are used to cover the possible colors.)
|
|
|
1239 */
|
|
|
1240 if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
|
|
|
1241 if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
|
|
|
1242 if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
|
|
|
1243 if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
|
|
|
1244 if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
|
|
|
1245 if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
|
|
|
1246 if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
|
|
|
1247 if (xy->whitey < 0 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
|
|
|
1248
|
|
|
1249 /* The reverse calculation is more difficult because the original tristimulus
|
|
|
1250 * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
|
|
|
1251 * derived values were recorded in the cHRM chunk;
|
|
|
1252 * (red,green,blue,white)x(x,y). This loses one degree of freedom and
|
|
|
1253 * therefore an arbitrary ninth value has to be introduced to undo the
|
|
|
1254 * original transformations.
|
|
|
1255 *
|
|
|
1256 * Think of the original end-points as points in (X,Y,Z) space. The
|
|
|
1257 * chromaticity values (c) have the property:
|
|
|
1258 *
|
|
|
1259 * C
|
|
|
1260 * c = ---------
|
|
|
1261 * X + Y + Z
|
|
|
1262 *
|
|
|
1263 * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
|
|
|
1264 * three chromaticity values (x,y,z) for each end-point obey the
|
|
|
1265 * relationship:
|
|
|
1266 *
|
|
|
1267 * x + y + z = 1
|
|
|
1268 *
|
|
|
1269 * This describes the plane in (X,Y,Z) space that intersects each axis at the
|
|
|
1270 * value 1.0; call this the chromaticity plane. Thus the chromaticity
|
|
|
1271 * calculation has scaled each end-point so that it is on the x+y+z=1 plane
|
|
|
1272 * and chromaticity is the intersection of the vector from the origin to the
|
|
|
1273 * (X,Y,Z) value with the chromaticity plane.
|
|
|
1274 *
|
|
|
1275 * To fully invert the chromaticity calculation we would need the three
|
|
|
1276 * end-point scale factors, (red-scale, green-scale, blue-scale), but these
|
|
|
1277 * were not recorded. Instead we calculated the reference white (X,Y,Z) and
|
|
|
1278 * recorded the chromaticity of this. The reference white (X,Y,Z) would have
|
|
|
1279 * given all three of the scale factors since:
|
|
|
1280 *
|
|
|
1281 * color-C = color-c * color-scale
|
|
|
1282 * white-C = red-C + green-C + blue-C
|
|
|
1283 * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
|
|
|
1284 *
|
|
|
1285 * But cHRM records only white-x and white-y, so we have lost the white scale
|
|
|
1286 * factor:
|
|
|
1287 *
|
|
|
1288 * white-C = white-c*white-scale
|
|
|
1289 *
|
|
|
1290 * To handle this the inverse transformation makes an arbitrary assumption
|
|
|
1291 * about white-scale:
|
|
|
1292 *
|
|
|
1293 * Assume: white-Y = 1.0
|
|
|
1294 * Hence: white-scale = 1/white-y
|
|
|
1295 * Or: red-Y + green-Y + blue-Y = 1.0
|
|
|
1296 *
|
|
|
1297 * Notice the last statement of the assumption gives an equation in three of
|
|
|
1298 * the nine values we want to calculate. 8 more equations come from the
|
|
|
1299 * above routine as summarised at the top above (the chromaticity
|
|
|
1300 * calculation):
|
|
|
1301 *
|
|
|
1302 * Given: color-x = color-X / (color-X + color-Y + color-Z)
|
|
|
1303 * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
|
|
|
1304 *
|
|
|
1305 * This is 9 simultaneous equations in the 9 variables "color-C" and can be
|
|
|
1306 * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
|
|
|
1307 * determinants, however this is not as bad as it seems because only 28 of
|
|
|
1308 * the total of 90 terms in the various matrices are non-zero. Nevertheless
|
|
|
1309 * Cramer's rule is notoriously numerically unstable because the determinant
|
|
|
1310 * calculation involves the difference of large, but similar, numbers. It is
|
|
|
1311 * difficult to be sure that the calculation is stable for real world values
|
|
|
1312 * and it is certain that it becomes unstable where the end points are close
|
|
|
1313 * together.
|
|
|
1314 *
|
|
|
1315 * So this code uses the perhaps slightly less optimal but more
|
|
|
1316 * understandable and totally obvious approach of calculating color-scale.
|
|
|
1317 *
|
|
|
1318 * This algorithm depends on the precision in white-scale and that is
|
|
|
1319 * (1/white-y), so we can immediately see that as white-y approaches 0 the
|
|
|
1320 * accuracy inherent in the cHRM chunk drops off substantially.
|
|
|
1321 *
|
|
|
1322 * libpng arithmetic: a simple invertion of the above equations
|
|
|
1323 * ------------------------------------------------------------
|
|
|
1324 *
|
|
|
1325 * white_scale = 1/white-y
|
|
|
1326 * white-X = white-x * white-scale
|
|
|
1327 * white-Y = 1.0
|
|
|
1328 * white-Z = (1 - white-x - white-y) * white_scale
|
|
|
1329 *
|
|
|
1330 * white-C = red-C + green-C + blue-C
|
|
|
1331 * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
|
|
|
1332 *
|
|
|
1333 * This gives us three equations in (red-scale,green-scale,blue-scale) where
|
|
|
1334 * all the coefficients are now known:
|
|
|
1335 *
|
|
|
1336 * red-x*red-scale + green-x*green-scale + blue-x*blue-scale
|
|
|
1337 * = white-x/white-y
|
|
|
1338 * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
|
|
|
1339 * red-z*red-scale + green-z*green-scale + blue-z*blue-scale
|
|
|
1340 * = (1 - white-x - white-y)/white-y
|
|
|
1341 *
|
|
|
1342 * In the last equation color-z is (1 - color-x - color-y) so we can add all
|
|
|
1343 * three equations together to get an alternative third:
|
|
|
1344 *
|
|
|
1345 * red-scale + green-scale + blue-scale = 1/white-y = white-scale
|
|
|
1346 *
|
|
|
1347 * So now we have a Cramer's rule solution where the determinants are just
|
|
|
1348 * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
|
|
|
1349 * multiplication of three coefficients so we can't guarantee to avoid
|
|
|
1350 * overflow in the libpng fixed point representation. Using Cramer's rule in
|
|
|
1351 * floating point is probably a good choice here, but it's not an option for
|
|
|
1352 * fixed point. Instead proceed to simplify the first two equations by
|
|
|
1353 * eliminating what is likely to be the largest value, blue-scale:
|
|
|
1354 *
|
|
|
1355 * blue-scale = white-scale - red-scale - green-scale
|
|
|
1356 *
|
|
|
1357 * Hence:
|
|
|
1358 *
|
|
|
1359 * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
|
|
|
1360 * (white-x - blue-x)*white-scale
|
|
|
1361 *
|
|
|
1362 * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
|
|
|
1363 * 1 - blue-y*white-scale
|
|
|
1364 *
|
|
|
1365 * And now we can trivially solve for (red-scale,green-scale):
|
|
|
1366 *
|
|
|
1367 * green-scale =
|
|
|
1368 * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
|
|
|
1369 * -----------------------------------------------------------
|
|
|
1370 * green-x - blue-x
|
|
|
1371 *
|
|
|
1372 * red-scale =
|
|
|
1373 * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
|
|
|
1374 * ---------------------------------------------------------
|
|
|
1375 * red-y - blue-y
|
|
|
1376 *
|
|
|
1377 * Hence:
|
|
|
1378 *
|
|
|
1379 * red-scale =
|
|
|
1380 * ( (green-x - blue-x) * (white-y - blue-y) -
|
|
|
1381 * (green-y - blue-y) * (white-x - blue-x) ) / white-y
|
|
|
1382 * -------------------------------------------------------------------------
|
|
|
1383 * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
|
|
|
1384 *
|
|
|
1385 * green-scale =
|
|
|
1386 * ( (red-y - blue-y) * (white-x - blue-x) -
|
|
|
1387 * (red-x - blue-x) * (white-y - blue-y) ) / white-y
|
|
|
1388 * -------------------------------------------------------------------------
|
|
|
1389 * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
|
|
|
1390 *
|
|
|
1391 * Accuracy:
|
|
|
1392 * The input values have 5 decimal digits of accuracy. The values are all in
|
|
|
1393 * the range 0 < value < 1, so simple products are in the same range but may
|
|
|
1394 * need up to 10 decimal digits to preserve the original precision and avoid
|
|
|
1395 * underflow. Because we are using a 32-bit signed representation we cannot
|
|
|
1396 * match this; the best is a little over 9 decimal digits, less than 10.
|
|
|
1397 *
|
|
|
1398 * The approach used here is to preserve the maximum precision within the
|
|
|
1399 * signed representation. Because the red-scale calculation above uses the
|
|
|
1400 * difference between two products of values that must be in the range -1..+1
|
|
|
1401 * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
|
|
|
1402 * factor is irrelevant in the calculation because it is applied to both
|
|
|
1403 * numerator and denominator.
|
|
|
1404 *
|
|
|
1405 * Note that the values of the differences of the products of the
|
|
|
1406 * chromaticities in the above equations tend to be small, for example for
|
|
|
1407 * the sRGB chromaticities they are:
|
|
|
1408 *
|
|
|
1409 * red numerator: -0.04751
|
|
|
1410 * green numerator: -0.08788
|
|
|
1411 * denominator: -0.2241 (without white-y multiplication)
|
|
|
1412 *
|
|
|
1413 * The resultant Y coefficients from the chromaticities of some widely used
|
|
|
1414 * color space definitions are (to 15 decimal places):
|
|
|
1415 *
|
|
|
1416 * sRGB
|
|
|
1417 * 0.212639005871510 0.715168678767756 0.072192315360734
|
|
|
1418 * Kodak ProPhoto
|
|
|
1419 * 0.288071128229293 0.711843217810102 0.000085653960605
|
|
|
1420 * Adobe RGB
|
|
|
1421 * 0.297344975250536 0.627363566255466 0.075291458493998
|
|
|
1422 * Adobe Wide Gamut RGB
|
|
|
1423 * 0.258728243040113 0.724682314948566 0.016589442011321
|
|
|
1424 */
|
|
|
1425 /* By the argument, above overflow should be impossible here. The return
|
|
|
1426 * value of 2 indicates an internal error to the caller.
|
|
|
1427 */
|
|
|
1428 if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7))
|
|
|
1429 return 2;
|
|
|
1430 if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7))
|
|
|
1431 return 2;
|
|
|
1432 denominator = left - right;
|
|
|
1433
|
|
|
1434 /* Now find the red numerator. */
|
|
|
1435 if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7))
|
|
|
1436 return 2;
|
|
|
1437 if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7))
|
|
|
1438 return 2;
|
|
|
1439
|
|
|
1440 /* Overflow is possible here and it indicates an extreme set of PNG cHRM
|
|
|
1441 * chunk values. This calculation actually returns the reciprocal of the
|
|
|
1442 * scale value because this allows us to delay the multiplication of white-y
|
|
|
1443 * into the denominator, which tends to produce a small number.
|
|
|
1444 */
|
|
|
1445 if (!png_muldiv(&red_inverse, xy->whitey, denominator, left-right) ||
|
|
|
1446 red_inverse <= xy->whitey /* r+g+b scales = white scale */)
|
|
|
1447 return 1;
|
|
|
1448
|
|
|
1449 /* Similarly for green_inverse: */
|
|
|
1450 if (!png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7))
|
|
|
1451 return 2;
|
|
|
1452 if (!png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7))
|
|
|
1453 return 2;
|
|
|
1454 if (!png_muldiv(&green_inverse, xy->whitey, denominator, left-right) ||
|
|
|
1455 green_inverse <= xy->whitey)
|
|
|
1456 return 1;
|
|
|
1457
|
|
|
1458 /* And the blue scale, the checks above guarantee this can't overflow but it
|
|
|
1459 * can still produce 0 for extreme cHRM values.
|
|
|
1460 */
|
|
|
1461 blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
|
|
|
1462 png_reciprocal(green_inverse);
|
|
|
1463 if (blue_scale <= 0) return 1;
|
|
|
1464
|
|
|
1465
|
|
|
1466 /* And fill in the png_XYZ: */
|
|
|
1467 if (!png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse)) return 1;
|
|
|
1468 if (!png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse)) return 1;
|
|
|
1469 if (!png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
|
|
|
1470 red_inverse))
|
|
|
1471 return 1;
|
|
|
1472
|
|
|
1473 if (!png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse))
|
|
|
1474 return 1;
|
|
|
1475 if (!png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse))
|
|
|
1476 return 1;
|
|
|
1477 if (!png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
|
|
|
1478 green_inverse))
|
|
|
1479 return 1;
|
|
|
1480
|
|
|
1481 if (!png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1)) return 1;
|
|
|
1482 if (!png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1)) return 1;
|
|
|
1483 if (!png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
|
|
|
1484 PNG_FP_1))
|
|
|
1485 return 1;
|
|
|
1486
|
|
|
1487 return 0; /*success*/
|
|
|
1488 }
|
|
|
1489
|
|
|
1490 static int
|
|
|
1491 png_XYZ_normalize(png_XYZ *XYZ)
|
|
|
1492 {
|
|
|
1493 png_int_32 Y;
|
|
|
1494
|
|
|
1495 if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
|
|
|
1496 XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
|
|
|
1497 XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
|
|
|
1498 return 1;
|
|
|
1499
|
|
|
1500 /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
|
|
|
1501 * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
|
|
|
1502 * relying on addition of two positive values producing a negative one is not
|
|
|
1503 * safe.
|
|
|
1504 */
|
|
|
1505 Y = XYZ->red_Y;
|
|
|
1506 if (0x7fffffff - Y < XYZ->green_X) return 1;
|
|
|
1507 Y += XYZ->green_Y;
|
|
|
1508 if (0x7fffffff - Y < XYZ->blue_X) return 1;
|
|
|
1509 Y += XYZ->blue_Y;
|
|
|
1510
|
|
|
1511 if (Y != PNG_FP_1)
|
|
|
1512 {
|
|
|
1513 if (!png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y)) return 1;
|
|
|
1514 if (!png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y)) return 1;
|
|
|
1515 if (!png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y)) return 1;
|
|
|
1516
|
|
|
1517 if (!png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y)) return 1;
|
|
|
1518 if (!png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y)) return 1;
|
|
|
1519 if (!png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y)) return 1;
|
|
|
1520
|
|
|
1521 if (!png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y)) return 1;
|
|
|
1522 if (!png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y)) return 1;
|
|
|
1523 if (!png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y)) return 1;
|
|
|
1524 }
|
|
|
1525
|
|
|
1526 return 0;
|
|
|
1527 }
|
|
|
1528
|
|
|
1529 static int
|
|
|
1530 png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
|
|
|
1531 {
|
|
|
1532 /* Allow an error of +/-0.01 (absolute value) on each chromaticity */
|
|
|
1533 return !(PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
|
|
|
1534 PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
|
|
|
1535 PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
|
|
|
1536 PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
|
|
|
1537 PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
|
|
|
1538 PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
|
|
|
1539 PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
|
|
|
1540 PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta));
|
|
|
1541 }
|
|
|
1542
|
|
|
1543 /* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
|
|
|
1544 * chunk chromaticities. Earlier checks used to simply look for the overflow
|
|
|
1545 * condition (where the determinant of the matrix to solve for XYZ ends up zero
|
|
|
1546 * because the chromaticity values are not all distinct.) Despite this it is
|
|
|
1547 * theoretically possible to produce chromaticities that are apparently valid
|
|
|
1548 * but that rapidly degrade to invalid, potentially crashing, sets because of
|
|
|
1549 * arithmetic inaccuracies when calculations are performed on them. The new
|
|
|
1550 * check is to round-trip xy -> XYZ -> xy and then check that the result is
|
|
|
1551 * within a small percentage of the original.
|
|
|
1552 */
|
|
|
1553 static int
|
|
|
1554 png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
|
|
|
1555 {
|
|
|
1556 int result;
|
|
|
1557 png_xy xy_test;
|
|
|
1558
|
|
|
1559 /* As a side-effect this routine also returns the XYZ endpoints. */
|
|
|
1560 result = png_XYZ_from_xy(XYZ, xy);
|
|
|
1561 if (result) return result;
|
|
|
1562
|
|
|
1563 result = png_xy_from_XYZ(&xy_test, XYZ);
|
|
|
1564 if (result) return result;
|
|
|
1565
|
|
|
1566 if (png_colorspace_endpoints_match(xy, &xy_test,
|
|
|
1567 5/*actually, the math is pretty accurate*/))
|
|
|
1568 return 0;
|
|
|
1569
|
|
|
1570 /* Too much slip */
|
|
|
1571 return 1;
|
|
|
1572 }
|
|
|
1573
|
|
|
1574 /* This is the check going the other way. The XYZ is modified to normalize it
|
|
|
1575 * (another side-effect) and the xy chromaticities are returned.
|
|
|
1576 */
|
|
|
1577 static int
|
|
|
1578 png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
|
|
|
1579 {
|
|
|
1580 int result;
|
|
|
1581 png_XYZ XYZtemp;
|
|
|
1582
|
|
|
1583 result = png_XYZ_normalize(XYZ);
|
|
|
1584 if (result) return result;
|
|
|
1585
|
|
|
1586 result = png_xy_from_XYZ(xy, XYZ);
|
|
|
1587 if (result) return result;
|
|
|
1588
|
|
|
1589 XYZtemp = *XYZ;
|
|
|
1590 return png_colorspace_check_xy(&XYZtemp, xy);
|
|
|
1591 }
|
|
|
1592
|
|
|
1593 /* Used to check for an endpoint match against sRGB */
|
|
|
1594 static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
|
|
|
1595 {
|
|
|
1596 /* color x y */
|
|
|
1597 /* red */ 64000, 33000,
|
|
|
1598 /* green */ 30000, 60000,
|
|
|
1599 /* blue */ 15000, 6000,
|
|
|
1600 /* white */ 31270, 32900
|
|
|
1601 };
|
|
|
1602
|
|
|
1603 static int
|
|
|
1604 png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
|
|
|
1605 png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
|
|
|
1606 int preferred)
|
|
|
1607 {
|
|
|
1608 if (colorspace->flags & PNG_COLORSPACE_INVALID)
|
|
|
1609 return 0;
|
|
|
1610
|
|
|
1611 /* The consistency check is performed on the chromaticities; this factors out
|
|
|
1612 * variations because of the normalization (or not) of the end point Y
|
|
|
1613 * values.
|
|
|
1614 */
|
|
|
1615 if (preferred < 2 && (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
|
|
|
1616 {
|
|
|
1617 /* The end points must be reasonably close to any we already have. The
|
|
|
1618 * following allows an error of up to +/-.001
|
|
|
1619 */
|
|
|
1620 if (!png_colorspace_endpoints_match(xy, &colorspace->end_points_xy, 100))
|
|
|
1621 {
|
|
|
1622 colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
1623 png_benign_error(png_ptr, "inconsistent chromaticities");
|
|
|
1624 return 0; /* failed */
|
|
|
1625 }
|
|
|
1626
|
|
|
1627 /* Only overwrite with preferred values */
|
|
|
1628 if (!preferred)
|
|
|
1629 return 1; /* ok, but no change */
|
|
|
1630 }
|
|
|
1631
|
|
|
1632 colorspace->end_points_xy = *xy;
|
|
|
1633 colorspace->end_points_XYZ = *XYZ;
|
|
|
1634 colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
|
|
|
1635
|
|
|
1636 /* The end points are normally quoted to two decimal digits, so allow +/-0.01
|
|
|
1637 * on this test.
|
|
|
1638 */
|
|
|
1639 if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000))
|
|
|
1640 colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
|
|
|
1641
|
|
|
1642 else
|
|
|
1643 colorspace->flags &= PNG_COLORSPACE_CANCEL(
|
|
|
1644 PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
|
|
|
1645
|
|
|
1646 return 2; /* ok and changed */
|
|
|
1647 }
|
|
|
1648
|
|
|
1649 int /* PRIVATE */
|
|
|
1650 png_colorspace_set_chromaticities(png_const_structrp png_ptr,
|
|
|
1651 png_colorspacerp colorspace, const png_xy *xy, int preferred)
|
|
|
1652 {
|
|
|
1653 /* We must check the end points to ensure they are reasonable - in the past
|
|
|
1654 * color management systems have crashed as a result of getting bogus
|
|
|
1655 * colorant values, while this isn't the fault of libpng it is the
|
|
|
1656 * responsibility of libpng because PNG carries the bomb and libpng is in a
|
|
|
1657 * position to protect against it.
|
|
|
1658 */
|
|
|
1659 png_XYZ XYZ;
|
|
|
1660
|
|
|
1661 switch (png_colorspace_check_xy(&XYZ, xy))
|
|
|
1662 {
|
|
|
1663 case 0: /* success */
|
|
|
1664 return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
|
|
|
1665 preferred);
|
|
|
1666
|
|
|
1667 case 1:
|
|
|
1668 /* We can't invert the chromaticities so we can't produce value XYZ
|
|
|
1669 * values. Likely as not a color management system will fail too.
|
|
|
1670 */
|
|
|
1671 colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
1672 png_benign_error(png_ptr, "invalid chromaticities");
|
|
|
1673 break;
|
|
|
1674
|
|
|
1675 default:
|
|
|
1676 /* libpng is broken; this should be a warning but if it happens we
|
|
|
1677 * want error reports so for the moment it is an error.
|
|
|
1678 */
|
|
|
1679 colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
1680 png_error(png_ptr, "internal error checking chromaticities");
|
|
|
1681 break;
|
|
|
1682 }
|
|
|
1683
|
|
|
1684 return 0; /* failed */
|
|
|
1685 }
|
|
|
1686
|
|
|
1687 int /* PRIVATE */
|
|
|
1688 png_colorspace_set_endpoints(png_const_structrp png_ptr,
|
|
|
1689 png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
|
|
|
1690 {
|
|
|
1691 png_XYZ XYZ = *XYZ_in;
|
|
|
1692 png_xy xy;
|
|
|
1693
|
|
|
1694 switch (png_colorspace_check_XYZ(&xy, &XYZ))
|
|
|
1695 {
|
|
|
1696 case 0:
|
|
|
1697 return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
|
|
|
1698 preferred);
|
|
|
1699
|
|
|
1700 case 1:
|
|
|
1701 /* End points are invalid. */
|
|
|
1702 colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
1703 png_benign_error(png_ptr, "invalid end points");
|
|
|
1704 break;
|
|
|
1705
|
|
|
1706 default:
|
|
|
1707 colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
1708 png_error(png_ptr, "internal error checking chromaticities");
|
|
|
1709 break;
|
|
|
1710 }
|
|
|
1711
|
|
|
1712 return 0; /* failed */
|
|
|
1713 }
|
|
|
1714
|
|
|
1715 #if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
|
|
|
1716 /* Error message generation */
|
|
|
1717 static char
|
|
|
1718 png_icc_tag_char(png_uint_32 byte)
|
|
|
1719 {
|
|
|
1720 byte &= 0xff;
|
|
|
1721 if (byte >= 32 && byte <= 126)
|
|
|
1722 return (char)byte;
|
|
|
1723 else
|
|
|
1724 return '?';
|
|
|
1725 }
|
|
|
1726
|
|
|
1727 static void
|
|
|
1728 png_icc_tag_name(char *name, png_uint_32 tag)
|
|
|
1729 {
|
|
|
1730 name[0] = '\'';
|
|
|
1731 name[1] = png_icc_tag_char(tag >> 24);
|
|
|
1732 name[2] = png_icc_tag_char(tag >> 16);
|
|
|
1733 name[3] = png_icc_tag_char(tag >> 8);
|
|
|
1734 name[4] = png_icc_tag_char(tag );
|
|
|
1735 name[5] = '\'';
|
|
|
1736 }
|
|
|
1737
|
|
|
1738 static int
|
|
|
1739 is_ICC_signature_char(png_alloc_size_t it)
|
|
|
1740 {
|
|
|
1741 return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
|
|
|
1742 (it >= 97 && it <= 122);
|
|
|
1743 }
|
|
|
1744
|
|
|
1745 static int
|
|
|
1746 is_ICC_signature(png_alloc_size_t it)
|
|
|
1747 {
|
|
|
1748 return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
|
|
|
1749 is_ICC_signature_char((it >> 16) & 0xff) &&
|
|
|
1750 is_ICC_signature_char((it >> 8) & 0xff) &&
|
|
|
1751 is_ICC_signature_char(it & 0xff);
|
|
|
1752 }
|
|
|
1753
|
|
|
1754 static int
|
|
|
1755 png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
|
1756 png_const_charp name, png_alloc_size_t value, png_const_charp reason)
|
|
|
1757 {
|
|
|
1758 size_t pos;
|
|
|
1759 char message[196]; /* see below for calculation */
|
|
|
1760
|
|
|
1761 if (colorspace != NULL)
|
|
|
1762 colorspace->flags |= PNG_COLORSPACE_INVALID;
|
|
|
1763
|
|
|
1764 pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
|
|
|
1765 pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
|
|
|
1766 pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
|
|
|
1767 if (is_ICC_signature(value))
|
|
|
1768 {
|
|
|
1769 /* So 'value' is at most 4 bytes and the following cast is safe */
|
|
|
1770 png_icc_tag_name(message+pos, (png_uint_32)value);
|
|
|
1771 pos += 6; /* total +8; less than the else clause */
|
|
|
1772 message[pos++] = ':';
|
|
|
1773 message[pos++] = ' ';
|
|
|
1774 }
|
|
|
1775 # ifdef PNG_WARNINGS_SUPPORTED
|
|
|
1776 else
|
|
|
1777 {
|
|
|
1778 char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
|
|
|
1779
|
|
|
1780 pos = png_safecat(message, (sizeof message), pos,
|
|
|
1781 png_format_number(number, number+(sizeof number),
|
|
|
1782 PNG_NUMBER_FORMAT_x, value));
|
|
|
1783 pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
|
|
|
1784 }
|
|
|
1785 # endif
|
|
|
1786 /* The 'reason' is an arbitrary message, allow +79 maximum 195 */
|
|
|
1787 pos = png_safecat(message, (sizeof message), pos, reason);
|
|
|
1788 PNG_UNUSED(pos)
|
|
|
1789
|
|
|
1790 /* This is recoverable, but make it unconditionally an app_error on write to
|
|
|
1791 * avoid writing invalid ICC profiles into PNG files. (I.e. we handle them
|
|
|
1792 * on read, with a warning, but on write unless the app turns off
|
|
|
1793 * application errors the PNG won't be written.)
|
|
|
1794 */
|
|
|
1795 png_chunk_report(png_ptr, message,
|
|
|
1796 (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
|
|
|
1797
|
|
|
1798 return 0;
|
|
|
1799 }
|
|
|
1800 #endif /* sRGB || iCCP */
|
|
|
1801
|
|
|
1802 #ifdef PNG_sRGB_SUPPORTED
|
|
|
1803 int /* PRIVATE */
|
|
|
1804 png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
|
1805 int intent)
|
|
|
1806 {
|
|
|
1807 /* sRGB sets known gamma, end points and (from the chunk) intent. */
|
|
|
1808 /* IMPORTANT: these are not necessarily the values found in an ICC profile
|
|
|
1809 * because ICC profiles store values adapted to a D50 environment; it is
|
|
|
1810 * expected that the ICC profile mediaWhitePointTag will be D50, see the
|
|
|
1811 * checks and code elsewhere to understand this better.
|
|
|
1812 *
|
|
|
1813 * These XYZ values, which are accurate to 5dp, produce rgb to gray
|
|
|
1814 * coefficients of (6968,23435,2366), which are reduced (because they add up
|
|
|
1815 * to 32769 not 32768) to (6968,23434,2366). These are the values that
|
|
|
1816 * libpng has traditionally used (and are the best values given the 15bit
|
|
|
1817 * algorithm used by the rgb to gray code.)
|
|
|
1818 */
|
|
|
1819 static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
|
|
|
1820 {
|
|
|
1821 /* color X Y Z */
|
|
|
1822 /* red */ 41239, 21264, 1933,
|
|
|
1823 /* green */ 35758, 71517, 11919,
|
|
|
1824 /* blue */ 18048, 7219, 95053
|
|
|
1825 };
|
|
|
1826
|
|
|
1827 /* Do nothing if the colorspace is already invalidated. */
|
|
|
1828 if (colorspace->flags & PNG_COLORSPACE_INVALID)
|
|
|
1829 return 0;
|
|
|
1830
|
|
|
1831 /* Check the intent, then check for existing settings. It is valid for the
|
|
|
1832 * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
|
|
|
1833 * be consistent with the correct values. If, however, this function is
|
|
|
1834 * called below because an iCCP chunk matches sRGB then it is quite
|
|
|
1835 * conceivable that an older app recorded incorrect gAMA and cHRM because of
|
|
|
1836 * an incorrect calculation based on the values in the profile - this does
|
|
|
1837 * *not* invalidate the profile (though it still produces an error, which can
|
|
|
1838 * be ignored.)
|
|
|
1839 */
|
|
|
1840 if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
|
|
|
1841 return png_icc_profile_error(png_ptr, colorspace, "sRGB",
|
|
|
1842 (unsigned)intent, "invalid sRGB rendering intent");
|
|
|
1843
|
|
|
1844 if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
|
|
|
1845 colorspace->rendering_intent != intent)
|
|
|
1846 return png_icc_profile_error(png_ptr, colorspace, "sRGB",
|
|
|
1847 (unsigned)intent, "inconsistent rendering intents");
|
|
|
1848
|
|
|
1849 if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
|
|
|
1850 {
|
|
|
1851 png_benign_error(png_ptr, "duplicate sRGB information ignored");
|
|
|
1852 return 0;
|
|
|
1853 }
|
|
|
1854
|
|
|
1855 /* If the standard sRGB cHRM chunk does not match the one from the PNG file
|
|
|
1856 * warn but overwrite the value with the correct one.
|
|
|
1857 */
|
|
|
1858 if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
|
|
|
1859 !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
|
|
|
1860 100))
|
|
|
1861 png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
|
|
|
1862 PNG_CHUNK_ERROR);
|
|
|
1863
|
|
|
1864 /* This check is just done for the error reporting - the routine always
|
|
|
1865 * returns true when the 'from' argument corresponds to sRGB (2).
|
|
|
1866 */
|
|
|
1867 (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
|
|
|
1868 2/*from sRGB*/);
|
|
|
1869
|
|
|
1870 /* intent: bugs in GCC force 'int' to be used as the parameter type. */
|
|
|
1871 colorspace->rendering_intent = (png_uint_16)intent;
|
|
|
1872 colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
|
|
|
1873
|
|
|
1874 /* endpoints */
|
|
|
1875 colorspace->end_points_xy = sRGB_xy;
|
|
|
1876 colorspace->end_points_XYZ = sRGB_XYZ;
|
|
|
1877 colorspace->flags |=
|
|
|
1878 (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
|
|
|
1879
|
|
|
1880 /* gamma */
|
|
|
1881 colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
|
|
|
1882 colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
|
|
|
1883
|
|
|
1884 /* Finally record that we have an sRGB profile */
|
|
|
1885 colorspace->flags |=
|
|
|
1886 (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
|
|
|
1887
|
|
|
1888 return 1; /* set */
|
|
|
1889 }
|
|
|
1890 #endif /* sRGB */
|
|
|
1891
|
|
|
1892 #ifdef PNG_iCCP_SUPPORTED
|
|
|
1893 /* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
|
|
|
1894 * is XYZ(0.9642,1.0,0.8249), which scales to:
|
|
|
1895 *
|
|
|
1896 * (63189.8112, 65536, 54060.6464)
|
|
|
1897 */
|
|
|
1898 static const png_byte D50_nCIEXYZ[12] =
|
|
|
1899 { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
|
|
|
1900
|
|
|
1901 int /* PRIVATE */
|
|
|
1902 png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
|
1903 png_const_charp name, png_uint_32 profile_length)
|
|
|
1904 {
|
|
|
1905 if (profile_length < 132)
|
|
|
1906 return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
|
|
1907 "too short");
|
|
|
1908
|
|
|
1909 if (profile_length & 3)
|
|
|
1910 return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
|
|
|
1911 "invalid length");
|
|
|
1912
|
|
|
1913 return 1;
|
|
|
1914 }
|
|
|
1915
|
|
|
1916 int /* PRIVATE */
|
|
|
1917 png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
|
1918 png_const_charp name, png_uint_32 profile_length,
|
|
|
1919 png_const_bytep profile/* first 132 bytes only */, int color_type)
|
|
|
1920 {
|
|
|
1921 png_uint_32 temp;
|
|
|
1922
|
|
|
1923 /* Length check; this cannot be ignored in this code because profile_length
|
|
|
1924 * is used later to check the tag table, so even if the profile seems over
|
|
|
1925 * long profile_length from the caller must be correct. The caller can fix
|
|
|
1926 * this up on read or write by just passing in the profile header length.
|
|
|
1927 */
|
|
|
1928 temp = png_get_uint_32(profile);
|
|
|
1929 if (temp != profile_length)
|
|
|
1930 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
1931 "length does not match profile");
|
|
|
1932
|
|
|
1933 temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
|
|
|
1934 if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
|
|
|
1935 profile_length < 132+12*temp) /* truncated tag table */
|
|
|
1936 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
1937 "tag count too large");
|
|
|
1938
|
|
|
1939 /* The 'intent' must be valid or we can't store it, ICC limits the intent to
|
|
|
1940 * 16 bits.
|
|
|
1941 */
|
|
|
1942 temp = png_get_uint_32(profile+64);
|
|
|
1943 if (temp >= 0xffff) /* The ICC limit */
|
|
|
1944 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
1945 "invalid rendering intent");
|
|
|
1946
|
|
|
1947 /* This is just a warning because the profile may be valid in future
|
|
|
1948 * versions.
|
|
|
1949 */
|
|
|
1950 if (temp >= PNG_sRGB_INTENT_LAST)
|
|
|
1951 (void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
|
|
1952 "intent outside defined range");
|
|
|
1953
|
|
|
1954 /* At this point the tag table can't be checked because it hasn't necessarily
|
|
|
1955 * been loaded; however, various header fields can be checked. These checks
|
|
|
1956 * are for values permitted by the PNG spec in an ICC profile; the PNG spec
|
|
|
1957 * restricts the profiles that can be passed in an iCCP chunk (they must be
|
|
|
1958 * appropriate to processing PNG data!)
|
|
|
1959 */
|
|
|
1960
|
|
|
1961 /* Data checks (could be skipped). These checks must be independent of the
|
|
|
1962 * version number; however, the version number doesn't accomodate changes in
|
|
|
1963 * the header fields (just the known tags and the interpretation of the
|
|
|
1964 * data.)
|
|
|
1965 */
|
|
|
1966 temp = png_get_uint_32(profile+36); /* signature 'ascp' */
|
|
|
1967 if (temp != 0x61637370)
|
|
|
1968 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
1969 "invalid signature");
|
|
|
1970
|
|
|
1971 /* Currently the PCS illuminant/adopted white point (the computational
|
|
|
1972 * white point) are required to be D50,
|
|
|
1973 * however the profile contains a record of the illuminant so perhaps ICC
|
|
|
1974 * expects to be able to change this in the future (despite the rationale in
|
|
|
1975 * the introduction for using a fixed PCS adopted white.) Consequently the
|
|
|
1976 * following is just a warning.
|
|
|
1977 */
|
|
|
1978 if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
|
|
|
1979 (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
|
|
|
1980 "PCS illuminant is not D50");
|
|
|
1981
|
|
|
1982 /* The PNG spec requires this:
|
|
|
1983 * "If the iCCP chunk is present, the image samples conform to the colour
|
|
|
1984 * space represented by the embedded ICC profile as defined by the
|
|
|
1985 * International Color Consortium [ICC]. The colour space of the ICC profile
|
|
|
1986 * shall be an RGB colour space for colour images (PNG colour types 2, 3, and
|
|
|
1987 * 6), or a greyscale colour space for greyscale images (PNG colour types 0
|
|
|
1988 * and 4)."
|
|
|
1989 *
|
|
|
1990 * This checking code ensures the embedded profile (on either read or write)
|
|
|
1991 * conforms to the specification requirements. Notice that an ICC 'gray'
|
|
|
1992 * color-space profile contains the information to transform the monochrome
|
|
|
1993 * data to XYZ or L*a*b (according to which PCS the profile uses) and this
|
|
|
1994 * should be used in preference to the standard libpng K channel replication
|
|
|
1995 * into R, G and B channels.
|
|
|
1996 *
|
|
|
1997 * Previously it was suggested that an RGB profile on grayscale data could be
|
|
|
1998 * handled. However it it is clear that using an RGB profile in this context
|
|
|
1999 * must be an error - there is no specification of what it means. Thus it is
|
|
|
2000 * almost certainly more correct to ignore the profile.
|
|
|
2001 */
|
|
|
2002 temp = png_get_uint_32(profile+16); /* data colour space field */
|
|
|
2003 switch (temp)
|
|
|
2004 {
|
|
|
2005 case 0x52474220: /* 'RGB ' */
|
|
|
2006 if (!(color_type & PNG_COLOR_MASK_COLOR))
|
|
|
2007 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
2008 "RGB color space not permitted on grayscale PNG");
|
|
|
2009 break;
|
|
|
2010
|
|
|
2011 case 0x47524159: /* 'GRAY' */
|
|
|
2012 if (color_type & PNG_COLOR_MASK_COLOR)
|
|
|
2013 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
2014 "Gray color space not permitted on RGB PNG");
|
|
|
2015 break;
|
|
|
2016
|
|
|
2017 default:
|
|
|
2018 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
2019 "invalid ICC profile color space");
|
|
|
2020 }
|
|
|
2021
|
|
|
2022 /* It is up to the application to check that the profile class matches the
|
|
|
2023 * application requirements; the spec provides no guidance, but it's pretty
|
|
|
2024 * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
|
|
|
2025 * ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
|
|
|
2026 * cases. Issue an error for device link or abstract profiles - these don't
|
|
|
2027 * contain the records necessary to transform the color-space to anything
|
|
|
2028 * other than the target device (and not even that for an abstract profile).
|
|
|
2029 * Profiles of these classes may not be embedded in images.
|
|
|
2030 */
|
|
|
2031 temp = png_get_uint_32(profile+12); /* profile/device class */
|
|
|
2032 switch (temp)
|
|
|
2033 {
|
|
|
2034 case 0x73636E72: /* 'scnr' */
|
|
|
2035 case 0x6D6E7472: /* 'mntr' */
|
|
|
2036 case 0x70727472: /* 'prtr' */
|
|
|
2037 case 0x73706163: /* 'spac' */
|
|
|
2038 /* All supported */
|
|
|
2039 break;
|
|
|
2040
|
|
|
2041 case 0x61627374: /* 'abst' */
|
|
|
2042 /* May not be embedded in an image */
|
|
|
2043 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
2044 "invalid embedded Abstract ICC profile");
|
|
|
2045
|
|
|
2046 case 0x6C696E6B: /* 'link' */
|
|
|
2047 /* DeviceLink profiles cannnot be interpreted in a non-device specific
|
|
|
2048 * fashion, if an app uses the AToB0Tag in the profile the results are
|
|
|
2049 * undefined unless the result is sent to the intended device,
|
|
|
2050 * therefore a DeviceLink profile should not be found embedded in a
|
|
|
2051 * PNG.
|
|
|
2052 */
|
|
|
2053 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
2054 "unexpected DeviceLink ICC profile class");
|
|
|
2055
|
|
|
2056 case 0x6E6D636C: /* 'nmcl' */
|
|
|
2057 /* A NamedColor profile is also device specific, however it doesn't
|
|
|
2058 * contain an AToB0 tag that is open to misintrepretation. Almost
|
|
|
2059 * certainly it will fail the tests below.
|
|
|
2060 */
|
|
|
2061 (void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
|
|
2062 "unexpected NamedColor ICC profile class");
|
|
|
2063 break;
|
|
|
2064
|
|
|
2065 default:
|
|
|
2066 /* To allow for future enhancements to the profile accept unrecognized
|
|
|
2067 * profile classes with a warning, these then hit the test below on the
|
|
|
2068 * tag content to ensure they are backward compatible with one of the
|
|
|
2069 * understood profiles.
|
|
|
2070 */
|
|
|
2071 (void)png_icc_profile_error(png_ptr, NULL, name, temp,
|
|
|
2072 "unrecognized ICC profile class");
|
|
|
2073 break;
|
|
|
2074 }
|
|
|
2075
|
|
|
2076 /* For any profile other than a device link one the PCS must be encoded
|
|
|
2077 * either in XYZ or Lab.
|
|
|
2078 */
|
|
|
2079 temp = png_get_uint_32(profile+20);
|
|
|
2080 switch (temp)
|
|
|
2081 {
|
|
|
2082 case 0x58595A20: /* 'XYZ ' */
|
|
|
2083 case 0x4C616220: /* 'Lab ' */
|
|
|
2084 break;
|
|
|
2085
|
|
|
2086 default:
|
|
|
2087 return png_icc_profile_error(png_ptr, colorspace, name, temp,
|
|
|
2088 "unexpected ICC PCS encoding");
|
|
|
2089 }
|
|
|
2090
|
|
|
2091 return 1;
|
|
|
2092 }
|
|
|
2093
|
|
|
2094 int /* PRIVATE */
|
|
|
2095 png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
|
2096 png_const_charp name, png_uint_32 profile_length,
|
|
|
2097 png_const_bytep profile /* header plus whole tag table */)
|
|
|
2098 {
|
|
|
2099 png_uint_32 tag_count = png_get_uint_32(profile+128);
|
|
|
2100 png_uint_32 itag;
|
|
|
2101 png_const_bytep tag = profile+132; /* The first tag */
|
|
|
2102
|
|
|
2103 /* First scan all the tags in the table and add bits to the icc_info value
|
|
|
2104 * (temporarily in 'tags').
|
|
|
2105 */
|
|
|
2106 for (itag=0; itag < tag_count; ++itag, tag += 12)
|
|
|
2107 {
|
|
|
2108 png_uint_32 tag_id = png_get_uint_32(tag+0);
|
|
|
2109 png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
|
|
|
2110 png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
|
|
|
2111
|
|
|
2112 /* The ICC specification does not exclude zero length tags, therefore the
|
|
|
2113 * start might actually be anywhere if there is no data, but this would be
|
|
|
2114 * a clear abuse of the intent of the standard so the start is checked for
|
|
|
2115 * being in range. All defined tag types have an 8 byte header - a 4 byte
|
|
|
2116 * type signature then 0.
|
|
|
2117 */
|
|
|
2118 if ((tag_start & 3) != 0)
|
|
|
2119 {
|
|
|
2120 /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
|
|
|
2121 * only a warning here because libpng does not care about the
|
|
|
2122 * alignment.
|
|
|
2123 */
|
|
|
2124 (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
|
|
|
2125 "ICC profile tag start not a multiple of 4");
|
|
|
2126 }
|
|
|
2127
|
|
|
2128 /* This is a hard error; potentially it can cause read outside the
|
|
|
2129 * profile.
|
|
|
2130 */
|
|
|
2131 if (tag_start > profile_length || tag_length > profile_length - tag_start)
|
|
|
2132 return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
|
|
|
2133 "ICC profile tag outside profile");
|
|
|
2134 }
|
|
|
2135
|
|
|
2136 return 1; /* success, maybe with warnings */
|
|
|
2137 }
|
|
|
2138
|
|
|
2139 #ifdef PNG_sRGB_SUPPORTED
|
|
|
2140 /* Information about the known ICC sRGB profiles */
|
|
|
2141 static const struct
|
|
|
2142 {
|
|
|
2143 png_uint_32 adler, crc, length;
|
|
|
2144 png_uint_32 md5[4];
|
|
|
2145 png_byte have_md5;
|
|
|
2146 png_byte is_broken;
|
|
|
2147 png_uint_16 intent;
|
|
|
2148
|
|
|
2149 # define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
|
|
|
2150 # define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
|
|
|
2151 { adler, crc, length, md5, broke, intent },
|
|
|
2152
|
|
|
2153 } png_sRGB_checks[] =
|
|
|
2154 {
|
|
|
2155 /* This data comes from contrib/tools/checksum-icc run on downloads of
|
|
|
2156 * all four ICC sRGB profiles from www.color.org.
|
|
|
2157 */
|
|
|
2158 /* adler32, crc32, MD5[4], intent, date, length, file-name */
|
|
|
2159 PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
|
|
|
2160 PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
|
|
|
2161 "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
|
|
|
2162
|
|
|
2163 /* ICC sRGB v2 perceptual no black-compensation: */
|
|
|
2164 PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
|
|
|
2165 PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
|
|
|
2166 "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
|
|
|
2167
|
|
|
2168 PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
|
|
|
2169 PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
|
|
|
2170 "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
|
|
|
2171
|
|
|
2172 /* ICC sRGB v4 perceptual */
|
|
|
2173 PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
|
|
|
2174 PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
|
|
|
2175 "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
|
|
|
2176
|
|
|
2177 /* The following profiles have no known MD5 checksum. If there is a match
|
|
|
2178 * on the (empty) MD5 the other fields are used to attempt a match and
|
|
|
2179 * a warning is produced. The first two of these profiles have a 'cprt' tag
|
|
|
2180 * which suggests that they were also made by Hewlett Packard.
|
|
|
2181 */
|
|
|
2182 PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
|
|
|
2183 PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
|
|
|
2184 "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
|
|
|
2185
|
|
|
2186 /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
|
|
|
2187 * match the D50 PCS illuminant in the header (it is in fact the D65 values,
|
|
|
2188 * so the white point is recorded as the un-adapted value.) The profiles
|
|
|
2189 * below only differ in one byte - the intent - and are basically the same as
|
|
|
2190 * the previous profile except for the mediaWhitePointTag error and a missing
|
|
|
2191 * chromaticAdaptationTag.
|
|
|
2192 */
|
|
|
2193 PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
|
|
|
2194 PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
|
|
|
2195 "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
|
|
|
2196
|
|
|
2197 PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
|
|
|
2198 PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
|
|
|
2199 "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
|
|
|
2200 };
|
|
|
2201
|
|
|
2202 static int
|
|
|
2203 png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
|
|
|
2204 png_const_bytep profile, uLong adler)
|
|
|
2205 {
|
|
|
2206 /* The quick check is to verify just the MD5 signature and trust the
|
|
|
2207 * rest of the data. Because the profile has already been verified for
|
|
|
2208 * correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
|
|
|
2209 * field too, so if the profile has been edited with an intent not defined
|
|
|
2210 * by sRGB (but maybe defined by a later ICC specification) the read of
|
|
|
2211 * the profile will fail at that point.
|
|
|
2212 */
|
|
|
2213 png_uint_32 length = 0;
|
|
|
2214 png_uint_32 intent = 0x10000; /* invalid */
|
|
|
2215 #if PNG_sRGB_PROFILE_CHECKS > 1
|
|
|
2216 uLong crc = 0; /* the value for 0 length data */
|
|
|
2217 #endif
|
|
|
2218 unsigned int i;
|
|
|
2219
|
|
|
2220 for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
|
|
|
2221 {
|
|
|
2222 if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
|
|
|
2223 png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
|
|
|
2224 png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
|
|
|
2225 png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
|
|
|
2226 {
|
|
|
2227 /* This may be one of the old HP profiles without an MD5, in that
|
|
|
2228 * case we can only use the length and Adler32 (note that these
|
|
|
2229 * are not used by default if there is an MD5!)
|
|
|
2230 */
|
|
|
2231 # if PNG_sRGB_PROFILE_CHECKS == 0
|
|
|
2232 if (png_sRGB_checks[i].have_md5)
|
|
|
2233 return 1+png_sRGB_checks[i].is_broken;
|
|
|
2234 # endif
|
|
|
2235
|
|
|
2236 /* Profile is unsigned or more checks have been configured in. */
|
|
|
2237 if (length == 0)
|
|
|
2238 {
|
|
|
2239 length = png_get_uint_32(profile);
|
|
|
2240 intent = png_get_uint_32(profile+64);
|
|
|
2241 }
|
|
|
2242
|
|
|
2243 /* Length *and* intent must match */
|
|
|
2244 if (length == png_sRGB_checks[i].length &&
|
|
|
2245 intent == png_sRGB_checks[i].intent)
|
|
|
2246 {
|
|
|
2247 /* Now calculate the adler32 if not done already. */
|
|
|
2248 if (adler == 0)
|
|
|
2249 {
|
|
|
2250 adler = adler32(0, NULL, 0);
|
|
|
2251 adler = adler32(adler, profile, length);
|
|
|
2252 }
|
|
|
2253
|
|
|
2254 if (adler == png_sRGB_checks[i].adler)
|
|
|
2255 {
|
|
|
2256 /* These basic checks suggest that the data has not been
|
|
|
2257 * modified, but if the check level is more than 1 perform
|
|
|
2258 * our own crc32 checksum on the data.
|
|
|
2259 */
|
|
|
2260 # if PNG_sRGB_PROFILE_CHECKS > 1
|
|
|
2261 if (crc == 0)
|
|
|
2262 {
|
|
|
2263 crc = crc32(0, NULL, 0);
|
|
|
2264 crc = crc32(crc, profile, length);
|
|
|
2265 }
|
|
|
2266
|
|
|
2267 /* So this check must pass for the 'return' below to happen.
|
|
|
2268 */
|
|
|
2269 if (crc == png_sRGB_checks[i].crc)
|
|
|
2270 # endif
|
|
|
2271 {
|
|
|
2272 if (png_sRGB_checks[i].is_broken)
|
|
|
2273 {
|
|
|
2274 /* These profiles are known to have bad data that may cause
|
|
|
2275 * problems if they are used, therefore attempt to
|
|
|
2276 * discourage their use, skip the 'have_md5' warning below,
|
|
|
2277 * which is made irrelevant by this error.
|
|
|
2278 */
|
|
|
2279 png_chunk_report(png_ptr, "known incorrect sRGB profile",
|
|
|
2280 PNG_CHUNK_ERROR);
|
|
|
2281 }
|
|
|
2282
|
|
|
2283 /* Warn that this being done; this isn't even an error since
|
|
|
2284 * the profile is perfectly valid, but it would be nice if
|
|
|
2285 * people used the up-to-date ones.
|
|
|
2286 */
|
|
|
2287 else if (!png_sRGB_checks[i].have_md5)
|
|
|
2288 {
|
|
|
2289 png_chunk_report(png_ptr,
|
|
|
2290 "out-of-date sRGB profile with no signature",
|
|
|
2291 PNG_CHUNK_WARNING);
|
|
|
2292 }
|
|
|
2293
|
|
|
2294 return 1+png_sRGB_checks[i].is_broken;
|
|
|
2295 }
|
|
|
2296 }
|
|
|
2297 }
|
|
|
2298
|
|
|
2299 # if PNG_sRGB_PROFILE_CHECKS > 0
|
|
|
2300 /* The signature matched, but the profile had been changed in some
|
|
|
2301 * way. This probably indicates a data error or uninformed hacking.
|
|
|
2302 * Fall through to "no match".
|
|
|
2303 */
|
|
|
2304 png_chunk_report(png_ptr,
|
|
|
2305 "Not recognizing known sRGB profile that has been edited",
|
|
|
2306 PNG_CHUNK_WARNING);
|
|
|
2307 break;
|
|
|
2308 # endif
|
|
|
2309 }
|
|
|
2310 }
|
|
|
2311
|
|
|
2312 return 0; /* no match */
|
|
|
2313 }
|
|
|
2314 #endif
|
|
|
2315
|
|
|
2316 #ifdef PNG_sRGB_SUPPORTED
|
|
|
2317 void /* PRIVATE */
|
|
|
2318 png_icc_set_sRGB(png_const_structrp png_ptr,
|
|
|
2319 png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
|
|
|
2320 {
|
|
|
2321 /* Is this profile one of the known ICC sRGB profiles? If it is, just set
|
|
|
2322 * the sRGB information.
|
|
|
2323 */
|
|
|
2324 if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler))
|
|
|
2325 (void)png_colorspace_set_sRGB(png_ptr, colorspace,
|
|
|
2326 (int)/*already checked*/png_get_uint_32(profile+64));
|
|
|
2327 }
|
|
|
2328 #endif /* PNG_READ_sRGB_SUPPORTED */
|
|
|
2329
|
|
|
2330 int /* PRIVATE */
|
|
|
2331 png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
|
|
|
2332 png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
|
|
|
2333 int color_type)
|
|
|
2334 {
|
|
|
2335 if (colorspace->flags & PNG_COLORSPACE_INVALID)
|
|
|
2336 return 0;
|
|
|
2337
|
|
|
2338 if (png_icc_check_length(png_ptr, colorspace, name, profile_length) &&
|
|
|
2339 png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
|
|
|
2340 color_type) &&
|
|
|
2341 png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
|
|
|
2342 profile))
|
|
|
2343 {
|
|
|
2344 # ifdef PNG_sRGB_SUPPORTED
|
|
|
2345 /* If no sRGB support, don't try storing sRGB information */
|
|
|
2346 png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
|
|
|
2347 # endif
|
|
|
2348 return 1;
|
|
|
2349 }
|
|
|
2350
|
|
|
2351 /* Failure case */
|
|
|
2352 return 0;
|
|
|
2353 }
|
|
|
2354 #endif /* iCCP */
|
|
|
2355
|
|
|
2356 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
|
|
|
2357 void /* PRIVATE */
|
|
|
2358 png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
|
|
|
2359 {
|
|
|
2360 /* Set the rgb_to_gray coefficients from the colorspace. */
|
|
|
2361 if (!png_ptr->rgb_to_gray_coefficients_set &&
|
|
|
2362 (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
|
|
|
2363 {
|
|
|
2364 /* png_set_background has not been called, get the coefficients from the Y
|
|
|
2365 * values of the colorspace colorants.
|
|
|
2366 */
|
|
|
2367 png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
|
|
|
2368 png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
|
|
|
2369 png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
|
|
|
2370 png_fixed_point total = r+g+b;
|
|
|
2371
|
|
|
2372 if (total > 0 &&
|
|
|
2373 r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
|
|
|
2374 g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
|
|
|
2375 b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
|
|
|
2376 r+g+b <= 32769)
|
|
|
2377 {
|
|
|
2378 /* We allow 0 coefficients here. r+g+b may be 32769 if two or
|
|
|
2379 * all of the coefficients were rounded up. Handle this by
|
|
|
2380 * reducing the *largest* coefficient by 1; this matches the
|
|
|
2381 * approach used for the default coefficients in pngrtran.c
|
|
|
2382 */
|
|
|
2383 int add = 0;
|
|
|
2384
|
|
|
2385 if (r+g+b > 32768)
|
|
|
2386 add = -1;
|
|
|
2387 else if (r+g+b < 32768)
|
|
|
2388 add = 1;
|
|
|
2389
|
|
|
2390 if (add != 0)
|
|
|
2391 {
|
|
|
2392 if (g >= r && g >= b)
|
|
|
2393 g += add;
|
|
|
2394 else if (r >= g && r >= b)
|
|
|
2395 r += add;
|
|
|
2396 else
|
|
|
2397 b += add;
|
|
|
2398 }
|
|
|
2399
|
|
|
2400 /* Check for an internal error. */
|
|
|
2401 if (r+g+b != 32768)
|
|
|
2402 png_error(png_ptr,
|
|
|
2403 "internal error handling cHRM coefficients");
|
|
|
2404
|
|
|
2405 else
|
|
|
2406 {
|
|
|
2407 png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
|
|
|
2408 png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
|
|
|
2409 }
|
|
|
2410 }
|
|
|
2411
|
|
|
2412 /* This is a png_error at present even though it could be ignored -
|
|
|
2413 * it should never happen, but it is important that if it does, the
|
|
|
2414 * bug is fixed.
|
|
|
2415 */
|
|
|
2416 else
|
|
|
2417 png_error(png_ptr, "internal error handling cHRM->XYZ");
|
|
|
2418 }
|
|
|
2419 }
|
|
|
2420 #endif
|
|
|
2421
|
|
|
2422 #endif /* COLORSPACE */
|
|
|
2423
|
|
|
2424 void /* PRIVATE */
|
|
|
2425 png_check_IHDR(png_const_structrp png_ptr,
|
|
|
2426 png_uint_32 width, png_uint_32 height, int bit_depth,
|
|
|
2427 int color_type, int interlace_type, int compression_type,
|
|
|
2428 int filter_type)
|
|
|
2429 {
|
|
|
2430 int error = 0;
|
|
|
2431
|
|
|
2432 /* Check for width and height valid values */
|
|
|
2433 if (width == 0)
|
|
|
2434 {
|
|
|
2435 png_warning(png_ptr, "Image width is zero in IHDR");
|
|
|
2436 error = 1;
|
|
|
2437 }
|
|
|
2438
|
|
|
2439 if (height == 0)
|
|
|
2440 {
|
|
|
2441 png_warning(png_ptr, "Image height is zero in IHDR");
|
|
|
2442 error = 1;
|
|
|
2443 }
|
|
|
2444
|
|
|
2445 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
|
|
|
2446 if (width > png_ptr->user_width_max)
|
|
|
2447
|
|
|
2448 # else
|
|
|
2449 if (width > PNG_USER_WIDTH_MAX)
|
|
|
2450 # endif
|
|
|
2451 {
|
|
|
2452 png_warning(png_ptr, "Image width exceeds user limit in IHDR");
|
|
|
2453 error = 1;
|
|
|
2454 }
|
|
|
2455
|
|
|
2456 # ifdef PNG_SET_USER_LIMITS_SUPPORTED
|
|
|
2457 if (height > png_ptr->user_height_max)
|
|
|
2458 # else
|
|
|
2459 if (height > PNG_USER_HEIGHT_MAX)
|
|
|
2460 # endif
|
|
|
2461 {
|
|
|
2462 png_warning(png_ptr, "Image height exceeds user limit in IHDR");
|
|
|
2463 error = 1;
|
|
|
2464 }
|
|
|
2465
|
|
|
2466 if (width > PNG_UINT_31_MAX)
|
|
|
2467 {
|
|
|
2468 png_warning(png_ptr, "Invalid image width in IHDR");
|
|
|
2469 error = 1;
|
|
|
2470 }
|
|
|
2471
|
|
|
2472 if (height > PNG_UINT_31_MAX)
|
|
|
2473 {
|
|
|
2474 png_warning(png_ptr, "Invalid image height in IHDR");
|
|
|
2475 error = 1;
|
|
|
2476 }
|
|
|
2477
|
|
|
2478 /* Check other values */
|
|
|
2479 if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
|
|
|
2480 bit_depth != 8 && bit_depth != 16)
|
|
|
2481 {
|
|
|
2482 png_warning(png_ptr, "Invalid bit depth in IHDR");
|
|
|
2483 error = 1;
|
|
|
2484 }
|
|
|
2485
|
|
|
2486 if (color_type < 0 || color_type == 1 ||
|
|
|
2487 color_type == 5 || color_type > 6)
|
|
|
2488 {
|
|
|
2489 png_warning(png_ptr, "Invalid color type in IHDR");
|
|
|
2490 error = 1;
|
|
|
2491 }
|
|
|
2492
|
|
|
2493 if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
|
|
|
2494 ((color_type == PNG_COLOR_TYPE_RGB ||
|
|
|
2495 color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
|
|
|
2496 color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
|
|
|
2497 {
|
|
|
2498 png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
|
|
|
2499 error = 1;
|
|
|
2500 }
|
|
|
2501
|
|
|
2502 if (interlace_type >= PNG_INTERLACE_LAST)
|
|
|
2503 {
|
|
|
2504 png_warning(png_ptr, "Unknown interlace method in IHDR");
|
|
|
2505 error = 1;
|
|
|
2506 }
|
|
|
2507
|
|
|
2508 if (compression_type != PNG_COMPRESSION_TYPE_BASE)
|
|
|
2509 {
|
|
|
2510 png_warning(png_ptr, "Unknown compression method in IHDR");
|
|
|
2511 error = 1;
|
|
|
2512 }
|
|
|
2513
|
|
|
2514 # ifdef PNG_MNG_FEATURES_SUPPORTED
|
|
|
2515 /* Accept filter_method 64 (intrapixel differencing) only if
|
|
|
2516 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
|
|
|
2517 * 2. Libpng did not read a PNG signature (this filter_method is only
|
|
|
2518 * used in PNG datastreams that are embedded in MNG datastreams) and
|
|
|
2519 * 3. The application called png_permit_mng_features with a mask that
|
|
|
2520 * included PNG_FLAG_MNG_FILTER_64 and
|
|
|
2521 * 4. The filter_method is 64 and
|
|
|
2522 * 5. The color_type is RGB or RGBA
|
|
|
2523 */
|
|
|
2524 if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) &&
|
|
|
2525 png_ptr->mng_features_permitted)
|
|
|
2526 png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
|
|
|
2527
|
|
|
2528 if (filter_type != PNG_FILTER_TYPE_BASE)
|
|
|
2529 {
|
|
|
2530 if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
|
|
|
2531 (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
|
|
|
2532 ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
|
|
|
2533 (color_type == PNG_COLOR_TYPE_RGB ||
|
|
|
2534 color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
|
|
|
2535 {
|
|
|
2536 png_warning(png_ptr, "Unknown filter method in IHDR");
|
|
|
2537 error = 1;
|
|
|
2538 }
|
|
|
2539
|
|
|
2540 if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE)
|
|
|
2541 {
|
|
|
2542 png_warning(png_ptr, "Invalid filter method in IHDR");
|
|
|
2543 error = 1;
|
|
|
2544 }
|
|
|
2545 }
|
|
|
2546
|
|
|
2547 # else
|
|
|
2548 if (filter_type != PNG_FILTER_TYPE_BASE)
|
|
|
2549 {
|
|
|
2550 png_warning(png_ptr, "Unknown filter method in IHDR");
|
|
|
2551 error = 1;
|
|
|
2552 }
|
|
|
2553 # endif
|
|
|
2554
|
|
|
2555 if (error == 1)
|
|
|
2556 png_error(png_ptr, "Invalid IHDR data");
|
|
|
2557 }
|
|
|
2558
|
|
|
2559 #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
|
|
|
2560 /* ASCII to fp functions */
|
|
|
2561 /* Check an ASCII formated floating point value, see the more detailed
|
|
|
2562 * comments in pngpriv.h
|
|
|
2563 */
|
|
|
2564 /* The following is used internally to preserve the sticky flags */
|
|
|
2565 #define png_fp_add(state, flags) ((state) |= (flags))
|
|
|
2566 #define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
|
|
|
2567
|
|
|
2568 int /* PRIVATE */
|
|
|
2569 png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
|
|
|
2570 png_size_tp whereami)
|
|
|
2571 {
|
|
|
2572 int state = *statep;
|
|
|
2573 png_size_t i = *whereami;
|
|
|
2574
|
|
|
2575 while (i < size)
|
|
|
2576 {
|
|
|
2577 int type;
|
|
|
2578 /* First find the type of the next character */
|
|
|
2579 switch (string[i])
|
|
|
2580 {
|
|
|
2581 case 43: type = PNG_FP_SAW_SIGN; break;
|
|
|
2582 case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
|
|
|
2583 case 46: type = PNG_FP_SAW_DOT; break;
|
|
|
2584 case 48: type = PNG_FP_SAW_DIGIT; break;
|
|
|
2585 case 49: case 50: case 51: case 52:
|
|
|
2586 case 53: case 54: case 55: case 56:
|
|
|
2587 case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
|
|
|
2588 case 69:
|
|
|
2589 case 101: type = PNG_FP_SAW_E; break;
|
|
|
2590 default: goto PNG_FP_End;
|
|
|
2591 }
|
|
|
2592
|
|
|
2593 /* Now deal with this type according to the current
|
|
|
2594 * state, the type is arranged to not overlap the
|
|
|
2595 * bits of the PNG_FP_STATE.
|
|
|
2596 */
|
|
|
2597 switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
|
|
|
2598 {
|
|
|
2599 case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
|
|
|
2600 if (state & PNG_FP_SAW_ANY)
|
|
|
2601 goto PNG_FP_End; /* not a part of the number */
|
|
|
2602
|
|
|
2603 png_fp_add(state, type);
|
|
|
2604 break;
|
|
|
2605
|
|
|
2606 case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
|
|
|
2607 /* Ok as trailer, ok as lead of fraction. */
|
|
|
2608 if (state & PNG_FP_SAW_DOT) /* two dots */
|
|
|
2609 goto PNG_FP_End;
|
|
|
2610
|
|
|
2611 else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */
|
|
|
2612 png_fp_add(state, type);
|
|
|
2613
|
|
|
2614 else
|
|
|
2615 png_fp_set(state, PNG_FP_FRACTION | type);
|
|
|
2616
|
|
|
2617 break;
|
|
|
2618
|
|
|
2619 case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
|
|
|
2620 if (state & PNG_FP_SAW_DOT) /* delayed fraction */
|
|
|
2621 png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
|
|
|
2622
|
|
|
2623 png_fp_add(state, type | PNG_FP_WAS_VALID);
|
|
|
2624
|
|
|
2625 break;
|
|
|
2626
|
|
|
2627 case PNG_FP_INTEGER + PNG_FP_SAW_E:
|
|
|
2628 if ((state & PNG_FP_SAW_DIGIT) == 0)
|
|
|
2629 goto PNG_FP_End;
|
|
|
2630
|
|
|
2631 png_fp_set(state, PNG_FP_EXPONENT);
|
|
|
2632
|
|
|
2633 break;
|
|
|
2634
|
|
|
2635 /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
|
|
|
2636 goto PNG_FP_End; ** no sign in fraction */
|
|
|
2637
|
|
|
2638 /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
|
|
|
2639 goto PNG_FP_End; ** Because SAW_DOT is always set */
|
|
|
2640
|
|
|
2641 case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
|
|
|
2642 png_fp_add(state, type | PNG_FP_WAS_VALID);
|
|
|
2643 break;
|
|
|
2644
|
|
|
2645 case PNG_FP_FRACTION + PNG_FP_SAW_E:
|
|
|
2646 /* This is correct because the trailing '.' on an
|
|
|
2647 * integer is handled above - so we can only get here
|
|
|
2648 * with the sequence ".E" (with no preceding digits).
|
|
|
2649 */
|
|
|
2650 if ((state & PNG_FP_SAW_DIGIT) == 0)
|
|
|
2651 goto PNG_FP_End;
|
|
|
2652
|
|
|
2653 png_fp_set(state, PNG_FP_EXPONENT);
|
|
|
2654
|
|
|
2655 break;
|
|
|
2656
|
|
|
2657 case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
|
|
|
2658 if (state & PNG_FP_SAW_ANY)
|
|
|
2659 goto PNG_FP_End; /* not a part of the number */
|
|
|
2660
|
|
|
2661 png_fp_add(state, PNG_FP_SAW_SIGN);
|
|
|
2662
|
|
|
2663 break;
|
|
|
2664
|
|
|
2665 /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
|
|
|
2666 goto PNG_FP_End; */
|
|
|
2667
|
|
|
2668 case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
|
|
|
2669 png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
|
|
|
2670
|
|
|
2671 break;
|
|
|
2672
|
|
|
2673 /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
|
|
|
2674 goto PNG_FP_End; */
|
|
|
2675
|
|
|
2676 default: goto PNG_FP_End; /* I.e. break 2 */
|
|
|
2677 }
|
|
|
2678
|
|
|
2679 /* The character seems ok, continue. */
|
|
|
2680 ++i;
|
|
|
2681 }
|
|
|
2682
|
|
|
2683 PNG_FP_End:
|
|
|
2684 /* Here at the end, update the state and return the correct
|
|
|
2685 * return code.
|
|
|
2686 */
|
|
|
2687 *statep = state;
|
|
|
2688 *whereami = i;
|
|
|
2689
|
|
|
2690 return (state & PNG_FP_SAW_DIGIT) != 0;
|
|
|
2691 }
|
|
|
2692
|
|
|
2693
|
|
|
2694 /* The same but for a complete string. */
|
|
|
2695 int
|
|
|
2696 png_check_fp_string(png_const_charp string, png_size_t size)
|
|
|
2697 {
|
|
|
2698 int state=0;
|
|
|
2699 png_size_t char_index=0;
|
|
|
2700
|
|
|
2701 if (png_check_fp_number(string, size, &state, &char_index) &&
|
|
|
2702 (char_index == size || string[char_index] == 0))
|
|
|
2703 return state /* must be non-zero - see above */;
|
|
|
2704
|
|
|
2705 return 0; /* i.e. fail */
|
|
|
2706 }
|
|
|
2707 #endif /* pCAL or sCAL */
|
|
|
2708
|
|
|
2709 #ifdef PNG_sCAL_SUPPORTED
|
|
|
2710 # ifdef PNG_FLOATING_POINT_SUPPORTED
|
|
|
2711 /* Utility used below - a simple accurate power of ten from an integral
|
|
|
2712 * exponent.
|
|
|
2713 */
|
|
|
2714 static double
|
|
|
2715 png_pow10(int power)
|
|
|
2716 {
|
|
|
2717 int recip = 0;
|
|
|
2718 double d = 1;
|
|
|
2719
|
|
|
2720 /* Handle negative exponent with a reciprocal at the end because
|
|
|
2721 * 10 is exact whereas .1 is inexact in base 2
|
|
|
2722 */
|
|
|
2723 if (power < 0)
|
|
|
2724 {
|
|
|
2725 if (power < DBL_MIN_10_EXP) return 0;
|
|
|
2726 recip = 1, power = -power;
|
|
|
2727 }
|
|
|
2728
|
|
|
2729 if (power > 0)
|
|
|
2730 {
|
|
|
2731 /* Decompose power bitwise. */
|
|
|
2732 double mult = 10;
|
|
|
2733 do
|
|
|
2734 {
|
|
|
2735 if (power & 1) d *= mult;
|
|
|
2736 mult *= mult;
|
|
|
2737 power >>= 1;
|
|
|
2738 }
|
|
|
2739 while (power > 0);
|
|
|
2740
|
|
|
2741 if (recip) d = 1/d;
|
|
|
2742 }
|
|
|
2743 /* else power is 0 and d is 1 */
|
|
|
2744
|
|
|
2745 return d;
|
|
|
2746 }
|
|
|
2747
|
|
|
2748 /* Function to format a floating point value in ASCII with a given
|
|
|
2749 * precision.
|
|
|
2750 */
|
|
|
2751 void /* PRIVATE */
|
|
|
2752 png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
|
|
|
2753 double fp, unsigned int precision)
|
|
|
2754 {
|
|
|
2755 /* We use standard functions from math.h, but not printf because
|
|
|
2756 * that would require stdio. The caller must supply a buffer of
|
|
|
2757 * sufficient size or we will png_error. The tests on size and
|
|
|
2758 * the space in ascii[] consumed are indicated below.
|
|
|
2759 */
|
|
|
2760 if (precision < 1)
|
|
|
2761 precision = DBL_DIG;
|
|
|
2762
|
|
|
2763 /* Enforce the limit of the implementation precision too. */
|
|
|
2764 if (precision > DBL_DIG+1)
|
|
|
2765 precision = DBL_DIG+1;
|
|
|
2766
|
|
|
2767 /* Basic sanity checks */
|
|
|
2768 if (size >= precision+5) /* See the requirements below. */
|
|
|
2769 {
|
|
|
2770 if (fp < 0)
|
|
|
2771 {
|
|
|
2772 fp = -fp;
|
|
|
2773 *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
|
|
|
2774 --size;
|
|
|
2775 }
|
|
|
2776
|
|
|
2777 if (fp >= DBL_MIN && fp <= DBL_MAX)
|
|
|
2778 {
|
|
|
2779 int exp_b10; /* A base 10 exponent */
|
|
|
2780 double base; /* 10^exp_b10 */
|
|
|
2781
|
|
|
2782 /* First extract a base 10 exponent of the number,
|
|
|
2783 * the calculation below rounds down when converting
|
|
|
2784 * from base 2 to base 10 (multiply by log10(2) -
|
|
|
2785 * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
|
|
|
2786 * be increased. Note that the arithmetic shift
|
|
|
2787 * performs a floor() unlike C arithmetic - using a
|
|
|
2788 * C multiply would break the following for negative
|
|
|
2789 * exponents.
|
|
|
2790 */
|
|
|
2791 (void)frexp(fp, &exp_b10); /* exponent to base 2 */
|
|
|
2792
|
|
|
2793 exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
|
|
|
2794
|
|
|
2795 /* Avoid underflow here. */
|
|
|
2796 base = png_pow10(exp_b10); /* May underflow */
|
|
|
2797
|
|
|
2798 while (base < DBL_MIN || base < fp)
|
|
|
2799 {
|
|
|
2800 /* And this may overflow. */
|
|
|
2801 double test = png_pow10(exp_b10+1);
|
|
|
2802
|
|
|
2803 if (test <= DBL_MAX)
|
|
|
2804 ++exp_b10, base = test;
|
|
|
2805
|
|
|
2806 else
|
|
|
2807 break;
|
|
|
2808 }
|
|
|
2809
|
|
|
2810 /* Normalize fp and correct exp_b10, after this fp is in the
|
|
|
2811 * range [.1,1) and exp_b10 is both the exponent and the digit
|
|
|
2812 * *before* which the decimal point should be inserted
|
|
|
2813 * (starting with 0 for the first digit). Note that this
|
|
|
2814 * works even if 10^exp_b10 is out of range because of the
|
|
|
2815 * test on DBL_MAX above.
|
|
|
2816 */
|
|
|
2817 fp /= base;
|
|
|
2818 while (fp >= 1) fp /= 10, ++exp_b10;
|
|
|
2819
|
|
|
2820 /* Because of the code above fp may, at this point, be
|
|
|
2821 * less than .1, this is ok because the code below can
|
|
|
2822 * handle the leading zeros this generates, so no attempt
|
|
|
2823 * is made to correct that here.
|
|
|
2824 */
|
|
|
2825
|
|
|
2826 {
|
|
|
2827 int czero, clead, cdigits;
|
|
|
2828 char exponent[10];
|
|
|
2829
|
|
|
2830 /* Allow up to two leading zeros - this will not lengthen
|
|
|
2831 * the number compared to using E-n.
|
|
|
2832 */
|
|
|
2833 if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
|
|
|
2834 {
|
|
|
2835 czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
|
|
|
2836 exp_b10 = 0; /* Dot added below before first output. */
|
|
|
2837 }
|
|
|
2838 else
|
|
|
2839 czero = 0; /* No zeros to add */
|
|
|
2840
|
|
|
2841 /* Generate the digit list, stripping trailing zeros and
|
|
|
2842 * inserting a '.' before a digit if the exponent is 0.
|
|
|
2843 */
|
|
|
2844 clead = czero; /* Count of leading zeros */
|
|
|
2845 cdigits = 0; /* Count of digits in list. */
|
|
|
2846
|
|
|
2847 do
|
|
|
2848 {
|
|
|
2849 double d;
|
|
|
2850
|
|
|
2851 fp *= 10;
|
|
|
2852 /* Use modf here, not floor and subtract, so that
|
|
|
2853 * the separation is done in one step. At the end
|
|
|
2854 * of the loop don't break the number into parts so
|
|
|
2855 * that the final digit is rounded.
|
|
|
2856 */
|
|
|
2857 if (cdigits+czero-clead+1 < (int)precision)
|
|
|
2858 fp = modf(fp, &d);
|
|
|
2859
|
|
|
2860 else
|
|
|
2861 {
|
|
|
2862 d = floor(fp + .5);
|
|
|
2863
|
|
|
2864 if (d > 9)
|
|
|
2865 {
|
|
|
2866 /* Rounding up to 10, handle that here. */
|
|
|
2867 if (czero > 0)
|
|
|
2868 {
|
|
|
2869 --czero, d = 1;
|
|
|
2870 if (cdigits == 0) --clead;
|
|
|
2871 }
|
|
|
2872 else
|
|
|
2873 {
|
|
|
2874 while (cdigits > 0 && d > 9)
|
|
|
2875 {
|
|
|
2876 int ch = *--ascii;
|
|
|
2877
|
|
|
2878 if (exp_b10 != (-1))
|
|
|
2879 ++exp_b10;
|
|
|
2880
|
|
|
2881 else if (ch == 46)
|
|
|
2882 {
|
|
|
2883 ch = *--ascii, ++size;
|
|
|
2884 /* Advance exp_b10 to '1', so that the
|
|
|
2885 * decimal point happens after the
|
|
|
2886 * previous digit.
|
|
|
2887 */
|
|
|
2888 exp_b10 = 1;
|
|
|
2889 }
|
|
|
2890
|
|
|
2891 --cdigits;
|
|
|
2892 d = ch - 47; /* I.e. 1+(ch-48) */
|
|
|
2893 }
|
|
|
2894
|
|
|
2895 /* Did we reach the beginning? If so adjust the
|
|
|
2896 * exponent but take into account the leading
|
|
|
2897 * decimal point.
|
|
|
2898 */
|
|
|
2899 if (d > 9) /* cdigits == 0 */
|
|
|
2900 {
|
|
|
2901 if (exp_b10 == (-1))
|
|
|
2902 {
|
|
|
2903 /* Leading decimal point (plus zeros?), if
|
|
|
2904 * we lose the decimal point here it must
|
|
|
2905 * be reentered below.
|
|
|
2906 */
|
|
|
2907 int ch = *--ascii;
|
|
|
2908
|
|
|
2909 if (ch == 46)
|
|
|
2910 ++size, exp_b10 = 1;
|
|
|
2911
|
|
|
2912 /* Else lost a leading zero, so 'exp_b10' is
|
|
|
2913 * still ok at (-1)
|
|
|
2914 */
|
|
|
2915 }
|
|
|
2916 else
|
|
|
2917 ++exp_b10;
|
|
|
2918
|
|
|
2919 /* In all cases we output a '1' */
|
|
|
2920 d = 1;
|
|
|
2921 }
|
|
|
2922 }
|
|
|
2923 }
|
|
|
2924 fp = 0; /* Guarantees termination below. */
|
|
|
2925 }
|
|
|
2926
|
|
|
2927 if (d == 0)
|
|
|
2928 {
|
|
|
2929 ++czero;
|
|
|
2930 if (cdigits == 0) ++clead;
|
|
|
2931 }
|
|
|
2932 else
|
|
|
2933 {
|
|
|
2934 /* Included embedded zeros in the digit count. */
|
|
|
2935 cdigits += czero - clead;
|
|
|
2936 clead = 0;
|
|
|
2937
|
|
|
2938 while (czero > 0)
|
|
|
2939 {
|
|
|
2940 /* exp_b10 == (-1) means we just output the decimal
|
|
|
2941 * place - after the DP don't adjust 'exp_b10' any
|
|
|
2942 * more!
|
|
|
2943 */
|
|
|
2944 if (exp_b10 != (-1))
|
|
|
2945 {
|
|
|
2946 if (exp_b10 == 0) *ascii++ = 46, --size;
|
|
|
2947 /* PLUS 1: TOTAL 4 */
|
|
|
2948 --exp_b10;
|
|
|
2949 }
|
|
|
2950 *ascii++ = 48, --czero;
|
|
|
2951 }
|
|
|
2952
|
|
|
2953 if (exp_b10 != (-1))
|
|
|
2954 {
|
|
|
2955 if (exp_b10 == 0) *ascii++ = 46, --size; /* counted
|
|
|
2956 above */
|
|
|
2957 --exp_b10;
|
|
|
2958 }
|
|
|
2959 *ascii++ = (char)(48 + (int)d), ++cdigits;
|
|
|
2960 }
|
|
|
2961 }
|
|
|
2962 while (cdigits+czero-clead < (int)precision && fp > DBL_MIN);
|
|
|
2963
|
|
|
2964 /* The total output count (max) is now 4+precision */
|
|
|
2965
|
|
|
2966 /* Check for an exponent, if we don't need one we are
|
|
|
2967 * done and just need to terminate the string. At
|
|
|
2968 * this point exp_b10==(-1) is effectively if flag - it got
|
|
|
2969 * to '-1' because of the decrement after outputing
|
|
|
2970 * the decimal point above (the exponent required is
|
|
|
2971 * *not* -1!)
|
|
|
2972 */
|
|
|
2973 if (exp_b10 >= (-1) && exp_b10 <= 2)
|
|
|
2974 {
|
|
|
2975 /* The following only happens if we didn't output the
|
|
|
2976 * leading zeros above for negative exponent, so this
|
|
|
2977 * doest add to the digit requirement. Note that the
|
|
|
2978 * two zeros here can only be output if the two leading
|
|
|
2979 * zeros were *not* output, so this doesn't increase
|
|
|
2980 * the output count.
|
|
|
2981 */
|
|
|
2982 while (--exp_b10 >= 0) *ascii++ = 48;
|
|
|
2983
|
|
|
2984 *ascii = 0;
|
|
|
2985
|
|
|
2986 /* Total buffer requirement (including the '\0') is
|
|
|
2987 * 5+precision - see check at the start.
|
|
|
2988 */
|
|
|
2989 return;
|
|
|
2990 }
|
|
|
2991
|
|
|
2992 /* Here if an exponent is required, adjust size for
|
|
|
2993 * the digits we output but did not count. The total
|
|
|
2994 * digit output here so far is at most 1+precision - no
|
|
|
2995 * decimal point and no leading or trailing zeros have
|
|
|
2996 * been output.
|
|
|
2997 */
|
|
|
2998 size -= cdigits;
|
|
|
2999
|
|
|
3000 *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */
|
|
|
3001
|
|
|
3002 /* The following use of an unsigned temporary avoids ambiguities in
|
|
|
3003 * the signed arithmetic on exp_b10 and permits GCC at least to do
|
|
|
3004 * better optimization.
|
|
|
3005 */
|
|
|
3006 {
|
|
|
3007 unsigned int uexp_b10;
|
|
|
3008
|
|
|
3009 if (exp_b10 < 0)
|
|
|
3010 {
|
|
|
3011 *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
|
|
|
3012 uexp_b10 = -exp_b10;
|
|
|
3013 }
|
|
|
3014
|
|
|
3015 else
|
|
|
3016 uexp_b10 = exp_b10;
|
|
|
3017
|
|
|
3018 cdigits = 0;
|
|
|
3019
|
|
|
3020 while (uexp_b10 > 0)
|
|
|
3021 {
|
|
|
3022 exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
|
|
|
3023 uexp_b10 /= 10;
|
|
|
3024 }
|
|
|
3025 }
|
|
|
3026
|
|
|
3027 /* Need another size check here for the exponent digits, so
|
|
|
3028 * this need not be considered above.
|
|
|
3029 */
|
|
|
3030 if ((int)size > cdigits)
|
|
|
3031 {
|
|
|
3032 while (cdigits > 0) *ascii++ = exponent[--cdigits];
|
|
|
3033
|
|
|
3034 *ascii = 0;
|
|
|
3035
|
|
|
3036 return;
|
|
|
3037 }
|
|
|
3038 }
|
|
|
3039 }
|
|
|
3040 else if (!(fp >= DBL_MIN))
|
|
|
3041 {
|
|
|
3042 *ascii++ = 48; /* '0' */
|
|
|
3043 *ascii = 0;
|
|
|
3044 return;
|
|
|
3045 }
|
|
|
3046 else
|
|
|
3047 {
|
|
|
3048 *ascii++ = 105; /* 'i' */
|
|
|
3049 *ascii++ = 110; /* 'n' */
|
|
|
3050 *ascii++ = 102; /* 'f' */
|
|
|
3051 *ascii = 0;
|
|
|
3052 return;
|
|
|
3053 }
|
|
|
3054 }
|
|
|
3055
|
|
|
3056 /* Here on buffer too small. */
|
|
|
3057 png_error(png_ptr, "ASCII conversion buffer too small");
|
|
|
3058 }
|
|
|
3059
|
|
|
3060 # endif /* FLOATING_POINT */
|
|
|
3061
|
|
|
3062 # ifdef PNG_FIXED_POINT_SUPPORTED
|
|
|
3063 /* Function to format a fixed point value in ASCII.
|
|
|
3064 */
|
|
|
3065 void /* PRIVATE */
|
|
|
3066 png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
|
|
|
3067 png_size_t size, png_fixed_point fp)
|
|
|
3068 {
|
|
|
3069 /* Require space for 10 decimal digits, a decimal point, a minus sign and a
|
|
|
3070 * trailing \0, 13 characters:
|
|
|
3071 */
|
|
|
3072 if (size > 12)
|
|
|
3073 {
|
|
|
3074 png_uint_32 num;
|
|
|
3075
|
|
|
3076 /* Avoid overflow here on the minimum integer. */
|
|
|
3077 if (fp < 0)
|
|
|
3078 *ascii++ = 45, --size, num = -fp;
|
|
|
3079 else
|
|
|
3080 num = fp;
|
|
|
3081
|
|
|
3082 if (num <= 0x80000000) /* else overflowed */
|
|
|
3083 {
|
|
|
3084 unsigned int ndigits = 0, first = 16 /* flag value */;
|
|
|
3085 char digits[10];
|
|
|
3086
|
|
|
3087 while (num)
|
|
|
3088 {
|
|
|
3089 /* Split the low digit off num: */
|
|
|
3090 unsigned int tmp = num/10;
|
|
|
3091 num -= tmp*10;
|
|
|
3092 digits[ndigits++] = (char)(48 + num);
|
|
|
3093 /* Record the first non-zero digit, note that this is a number
|
|
|
3094 * starting at 1, it's not actually the array index.
|
|
|
3095 */
|
|
|
3096 if (first == 16 && num > 0)
|
|
|
3097 first = ndigits;
|
|
|
3098 num = tmp;
|
|
|
3099 }
|
|
|
3100
|
|
|
3101 if (ndigits > 0)
|
|
|
3102 {
|
|
|
3103 while (ndigits > 5) *ascii++ = digits[--ndigits];
|
|
|
3104 /* The remaining digits are fractional digits, ndigits is '5' or
|
|
|
3105 * smaller at this point. It is certainly not zero. Check for a
|
|
|
3106 * non-zero fractional digit:
|
|
|
3107 */
|
|
|
3108 if (first <= 5)
|
|
|
3109 {
|
|
|
3110 unsigned int i;
|
|
|
3111 *ascii++ = 46; /* decimal point */
|
|
|
3112 /* ndigits may be <5 for small numbers, output leading zeros
|
|
|
3113 * then ndigits digits to first:
|
|
|
3114 */
|
|
|
3115 i = 5;
|
|
|
3116 while (ndigits < i) *ascii++ = 48, --i;
|
|
|
3117 while (ndigits >= first) *ascii++ = digits[--ndigits];
|
|
|
3118 /* Don't output the trailing zeros! */
|
|
|
3119 }
|
|
|
3120 }
|
|
|
3121 else
|
|
|
3122 *ascii++ = 48;
|
|
|
3123
|
|
|
3124 /* And null terminate the string: */
|
|
|
3125 *ascii = 0;
|
|
|
3126 return;
|
|
|
3127 }
|
|
|
3128 }
|
|
|
3129
|
|
|
3130 /* Here on buffer too small. */
|
|
|
3131 png_error(png_ptr, "ASCII conversion buffer too small");
|
|
|
3132 }
|
|
|
3133 # endif /* FIXED_POINT */
|
|
|
3134 #endif /* READ_SCAL */
|
|
|
3135
|
|
|
3136 #if defined(PNG_FLOATING_POINT_SUPPORTED) && \
|
|
|
3137 !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
|
|
|
3138 (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
|
|
|
3139 defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
|
3140 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
|
|
|
3141 (defined(PNG_sCAL_SUPPORTED) && \
|
|
|
3142 defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
|
|
|
3143 png_fixed_point
|
|
|
3144 png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
|
|
|
3145 {
|
|
|
3146 double r = floor(100000 * fp + .5);
|
|
|
3147
|
|
|
3148 if (r > 2147483647. || r < -2147483648.)
|
|
|
3149 png_fixed_error(png_ptr, text);
|
|
|
3150
|
|
|
3151 # ifndef PNG_ERROR_TEXT_SUPPORTED
|
|
|
3152 PNG_UNUSED(text)
|
|
|
3153 # endif
|
|
|
3154
|
|
|
3155 return (png_fixed_point)r;
|
|
|
3156 }
|
|
|
3157 #endif
|
|
|
3158
|
|
|
3159 #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\
|
|
|
3160 defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
|
|
|
3161 /* muldiv functions */
|
|
|
3162 /* This API takes signed arguments and rounds the result to the nearest
|
|
|
3163 * integer (or, for a fixed point number - the standard argument - to
|
|
|
3164 * the nearest .00001). Overflow and divide by zero are signalled in
|
|
|
3165 * the result, a boolean - true on success, false on overflow.
|
|
|
3166 */
|
|
|
3167 int
|
|
|
3168 png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
|
|
|
3169 png_int_32 divisor)
|
|
|
3170 {
|
|
|
3171 /* Return a * times / divisor, rounded. */
|
|
|
3172 if (divisor != 0)
|
|
|
3173 {
|
|
|
3174 if (a == 0 || times == 0)
|
|
|
3175 {
|
|
|
3176 *res = 0;
|
|
|
3177 return 1;
|
|
|
3178 }
|
|
|
3179 else
|
|
|
3180 {
|
|
|
3181 #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3182 double r = a;
|
|
|
3183 r *= times;
|
|
|
3184 r /= divisor;
|
|
|
3185 r = floor(r+.5);
|
|
|
3186
|
|
|
3187 /* A png_fixed_point is a 32-bit integer. */
|
|
|
3188 if (r <= 2147483647. && r >= -2147483648.)
|
|
|
3189 {
|
|
|
3190 *res = (png_fixed_point)r;
|
|
|
3191 return 1;
|
|
|
3192 }
|
|
|
3193 #else
|
|
|
3194 int negative = 0;
|
|
|
3195 png_uint_32 A, T, D;
|
|
|
3196 png_uint_32 s16, s32, s00;
|
|
|
3197
|
|
|
3198 if (a < 0)
|
|
|
3199 negative = 1, A = -a;
|
|
|
3200 else
|
|
|
3201 A = a;
|
|
|
3202
|
|
|
3203 if (times < 0)
|
|
|
3204 negative = !negative, T = -times;
|
|
|
3205 else
|
|
|
3206 T = times;
|
|
|
3207
|
|
|
3208 if (divisor < 0)
|
|
|
3209 negative = !negative, D = -divisor;
|
|
|
3210 else
|
|
|
3211 D = divisor;
|
|
|
3212
|
|
|
3213 /* Following can't overflow because the arguments only
|
|
|
3214 * have 31 bits each, however the result may be 32 bits.
|
|
|
3215 */
|
|
|
3216 s16 = (A >> 16) * (T & 0xffff) +
|
|
|
3217 (A & 0xffff) * (T >> 16);
|
|
|
3218 /* Can't overflow because the a*times bit is only 30
|
|
|
3219 * bits at most.
|
|
|
3220 */
|
|
|
3221 s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
|
|
|
3222 s00 = (A & 0xffff) * (T & 0xffff);
|
|
|
3223
|
|
|
3224 s16 = (s16 & 0xffff) << 16;
|
|
|
3225 s00 += s16;
|
|
|
3226
|
|
|
3227 if (s00 < s16)
|
|
|
3228 ++s32; /* carry */
|
|
|
3229
|
|
|
3230 if (s32 < D) /* else overflow */
|
|
|
3231 {
|
|
|
3232 /* s32.s00 is now the 64-bit product, do a standard
|
|
|
3233 * division, we know that s32 < D, so the maximum
|
|
|
3234 * required shift is 31.
|
|
|
3235 */
|
|
|
3236 int bitshift = 32;
|
|
|
3237 png_fixed_point result = 0; /* NOTE: signed */
|
|
|
3238
|
|
|
3239 while (--bitshift >= 0)
|
|
|
3240 {
|
|
|
3241 png_uint_32 d32, d00;
|
|
|
3242
|
|
|
3243 if (bitshift > 0)
|
|
|
3244 d32 = D >> (32-bitshift), d00 = D << bitshift;
|
|
|
3245
|
|
|
3246 else
|
|
|
3247 d32 = 0, d00 = D;
|
|
|
3248
|
|
|
3249 if (s32 > d32)
|
|
|
3250 {
|
|
|
3251 if (s00 < d00) --s32; /* carry */
|
|
|
3252 s32 -= d32, s00 -= d00, result += 1<<bitshift;
|
|
|
3253 }
|
|
|
3254
|
|
|
3255 else
|
|
|
3256 if (s32 == d32 && s00 >= d00)
|
|
|
3257 s32 = 0, s00 -= d00, result += 1<<bitshift;
|
|
|
3258 }
|
|
|
3259
|
|
|
3260 /* Handle the rounding. */
|
|
|
3261 if (s00 >= (D >> 1))
|
|
|
3262 ++result;
|
|
|
3263
|
|
|
3264 if (negative)
|
|
|
3265 result = -result;
|
|
|
3266
|
|
|
3267 /* Check for overflow. */
|
|
|
3268 if ((negative && result <= 0) || (!negative && result >= 0))
|
|
|
3269 {
|
|
|
3270 *res = result;
|
|
|
3271 return 1;
|
|
|
3272 }
|
|
|
3273 }
|
|
|
3274 #endif
|
|
|
3275 }
|
|
|
3276 }
|
|
|
3277
|
|
|
3278 return 0;
|
|
|
3279 }
|
|
|
3280 #endif /* READ_GAMMA || INCH_CONVERSIONS */
|
|
|
3281
|
|
|
3282 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
|
|
|
3283 /* The following is for when the caller doesn't much care about the
|
|
|
3284 * result.
|
|
|
3285 */
|
|
|
3286 png_fixed_point
|
|
|
3287 png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
|
|
|
3288 png_int_32 divisor)
|
|
|
3289 {
|
|
|
3290 png_fixed_point result;
|
|
|
3291
|
|
|
3292 if (png_muldiv(&result, a, times, divisor))
|
|
|
3293 return result;
|
|
|
3294
|
|
|
3295 png_warning(png_ptr, "fixed point overflow ignored");
|
|
|
3296 return 0;
|
|
|
3297 }
|
|
|
3298 #endif
|
|
|
3299
|
|
|
3300 #ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
|
|
|
3301 /* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
|
|
|
3302 png_fixed_point
|
|
|
3303 png_reciprocal(png_fixed_point a)
|
|
|
3304 {
|
|
|
3305 #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3306 double r = floor(1E10/a+.5);
|
|
|
3307
|
|
|
3308 if (r <= 2147483647. && r >= -2147483648.)
|
|
|
3309 return (png_fixed_point)r;
|
|
|
3310 #else
|
|
|
3311 png_fixed_point res;
|
|
|
3312
|
|
|
3313 if (png_muldiv(&res, 100000, 100000, a))
|
|
|
3314 return res;
|
|
|
3315 #endif
|
|
|
3316
|
|
|
3317 return 0; /* error/overflow */
|
|
|
3318 }
|
|
|
3319
|
|
|
3320 /* This is the shared test on whether a gamma value is 'significant' - whether
|
|
|
3321 * it is worth doing gamma correction.
|
|
|
3322 */
|
|
|
3323 int /* PRIVATE */
|
|
|
3324 png_gamma_significant(png_fixed_point gamma_val)
|
|
|
3325 {
|
|
|
3326 return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
|
|
|
3327 gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
|
|
|
3328 }
|
|
|
3329 #endif
|
|
|
3330
|
|
|
3331 #ifdef PNG_READ_GAMMA_SUPPORTED
|
|
|
3332 # ifdef PNG_16BIT_SUPPORTED
|
|
|
3333 /* A local convenience routine. */
|
|
|
3334 static png_fixed_point
|
|
|
3335 png_product2(png_fixed_point a, png_fixed_point b)
|
|
|
3336 {
|
|
|
3337 /* The required result is 1/a * 1/b; the following preserves accuracy. */
|
|
|
3338 # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3339 double r = a * 1E-5;
|
|
|
3340 r *= b;
|
|
|
3341 r = floor(r+.5);
|
|
|
3342
|
|
|
3343 if (r <= 2147483647. && r >= -2147483648.)
|
|
|
3344 return (png_fixed_point)r;
|
|
|
3345 # else
|
|
|
3346 png_fixed_point res;
|
|
|
3347
|
|
|
3348 if (png_muldiv(&res, a, b, 100000))
|
|
|
3349 return res;
|
|
|
3350 # endif
|
|
|
3351
|
|
|
3352 return 0; /* overflow */
|
|
|
3353 }
|
|
|
3354 # endif /* 16BIT */
|
|
|
3355
|
|
|
3356 /* The inverse of the above. */
|
|
|
3357 png_fixed_point
|
|
|
3358 png_reciprocal2(png_fixed_point a, png_fixed_point b)
|
|
|
3359 {
|
|
|
3360 /* The required result is 1/a * 1/b; the following preserves accuracy. */
|
|
|
3361 #ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3362 double r = 1E15/a;
|
|
|
3363 r /= b;
|
|
|
3364 r = floor(r+.5);
|
|
|
3365
|
|
|
3366 if (r <= 2147483647. && r >= -2147483648.)
|
|
|
3367 return (png_fixed_point)r;
|
|
|
3368 #else
|
|
|
3369 /* This may overflow because the range of png_fixed_point isn't symmetric,
|
|
|
3370 * but this API is only used for the product of file and screen gamma so it
|
|
|
3371 * doesn't matter that the smallest number it can produce is 1/21474, not
|
|
|
3372 * 1/100000
|
|
|
3373 */
|
|
|
3374 png_fixed_point res = png_product2(a, b);
|
|
|
3375
|
|
|
3376 if (res != 0)
|
|
|
3377 return png_reciprocal(res);
|
|
|
3378 #endif
|
|
|
3379
|
|
|
3380 return 0; /* overflow */
|
|
|
3381 }
|
|
|
3382 #endif /* READ_GAMMA */
|
|
|
3383
|
|
|
3384 #ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
|
|
|
3385 #ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3386 /* Fixed point gamma.
|
|
|
3387 *
|
|
|
3388 * The code to calculate the tables used below can be found in the shell script
|
|
|
3389 * contrib/tools/intgamma.sh
|
|
|
3390 *
|
|
|
3391 * To calculate gamma this code implements fast log() and exp() calls using only
|
|
|
3392 * fixed point arithmetic. This code has sufficient precision for either 8-bit
|
|
|
3393 * or 16-bit sample values.
|
|
|
3394 *
|
|
|
3395 * The tables used here were calculated using simple 'bc' programs, but C double
|
|
|
3396 * precision floating point arithmetic would work fine.
|
|
|
3397 *
|
|
|
3398 * 8-bit log table
|
|
|
3399 * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
|
|
|
3400 * 255, so it's the base 2 logarithm of a normalized 8-bit floating point
|
|
|
3401 * mantissa. The numbers are 32-bit fractions.
|
|
|
3402 */
|
|
|
3403 static const png_uint_32
|
|
|
3404 png_8bit_l2[128] =
|
|
|
3405 {
|
|
|
3406 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
|
|
|
3407 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
|
|
|
3408 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
|
|
|
3409 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
|
|
|
3410 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
|
|
|
3411 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
|
|
|
3412 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
|
|
|
3413 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
|
|
|
3414 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
|
|
|
3415 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
|
|
|
3416 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
|
|
|
3417 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
|
|
|
3418 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
|
|
|
3419 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
|
|
|
3420 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
|
|
|
3421 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
|
|
|
3422 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
|
|
|
3423 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
|
|
|
3424 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
|
|
|
3425 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
|
|
|
3426 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
|
|
|
3427 24347096U, 0U
|
|
|
3428
|
|
|
3429 #if 0
|
|
|
3430 /* The following are the values for 16-bit tables - these work fine for the
|
|
|
3431 * 8-bit conversions but produce very slightly larger errors in the 16-bit
|
|
|
3432 * log (about 1.2 as opposed to 0.7 absolute error in the final value). To
|
|
|
3433 * use these all the shifts below must be adjusted appropriately.
|
|
|
3434 */
|
|
|
3435 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
|
|
|
3436 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
|
|
|
3437 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
|
|
|
3438 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
|
|
|
3439 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
|
|
|
3440 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
|
|
|
3441 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
|
|
|
3442 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
|
|
|
3443 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
|
|
|
3444 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
|
|
|
3445 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
|
|
|
3446 1119, 744, 372
|
|
|
3447 #endif
|
|
|
3448 };
|
|
|
3449
|
|
|
3450 static png_int_32
|
|
|
3451 png_log8bit(unsigned int x)
|
|
|
3452 {
|
|
|
3453 unsigned int lg2 = 0;
|
|
|
3454 /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
|
|
|
3455 * because the log is actually negate that means adding 1. The final
|
|
|
3456 * returned value thus has the range 0 (for 255 input) to 7.994 (for 1
|
|
|
3457 * input), return -1 for the overflow (log 0) case, - so the result is
|
|
|
3458 * always at most 19 bits.
|
|
|
3459 */
|
|
|
3460 if ((x &= 0xff) == 0)
|
|
|
3461 return -1;
|
|
|
3462
|
|
|
3463 if ((x & 0xf0) == 0)
|
|
|
3464 lg2 = 4, x <<= 4;
|
|
|
3465
|
|
|
3466 if ((x & 0xc0) == 0)
|
|
|
3467 lg2 += 2, x <<= 2;
|
|
|
3468
|
|
|
3469 if ((x & 0x80) == 0)
|
|
|
3470 lg2 += 1, x <<= 1;
|
|
|
3471
|
|
|
3472 /* result is at most 19 bits, so this cast is safe: */
|
|
|
3473 return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
|
|
|
3474 }
|
|
|
3475
|
|
|
3476 /* The above gives exact (to 16 binary places) log2 values for 8-bit images,
|
|
|
3477 * for 16-bit images we use the most significant 8 bits of the 16-bit value to
|
|
|
3478 * get an approximation then multiply the approximation by a correction factor
|
|
|
3479 * determined by the remaining up to 8 bits. This requires an additional step
|
|
|
3480 * in the 16-bit case.
|
|
|
3481 *
|
|
|
3482 * We want log2(value/65535), we have log2(v'/255), where:
|
|
|
3483 *
|
|
|
3484 * value = v' * 256 + v''
|
|
|
3485 * = v' * f
|
|
|
3486 *
|
|
|
3487 * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
|
|
|
3488 * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
|
|
|
3489 * than 258. The final factor also needs to correct for the fact that our 8-bit
|
|
|
3490 * value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
|
|
|
3491 *
|
|
|
3492 * This gives a final formula using a calculated value 'x' which is value/v' and
|
|
|
3493 * scaling by 65536 to match the above table:
|
|
|
3494 *
|
|
|
3495 * log2(x/257) * 65536
|
|
|
3496 *
|
|
|
3497 * Since these numbers are so close to '1' we can use simple linear
|
|
|
3498 * interpolation between the two end values 256/257 (result -368.61) and 258/257
|
|
|
3499 * (result 367.179). The values used below are scaled by a further 64 to give
|
|
|
3500 * 16-bit precision in the interpolation:
|
|
|
3501 *
|
|
|
3502 * Start (256): -23591
|
|
|
3503 * Zero (257): 0
|
|
|
3504 * End (258): 23499
|
|
|
3505 */
|
|
|
3506 static png_int_32
|
|
|
3507 png_log16bit(png_uint_32 x)
|
|
|
3508 {
|
|
|
3509 unsigned int lg2 = 0;
|
|
|
3510
|
|
|
3511 /* As above, but now the input has 16 bits. */
|
|
|
3512 if ((x &= 0xffff) == 0)
|
|
|
3513 return -1;
|
|
|
3514
|
|
|
3515 if ((x & 0xff00) == 0)
|
|
|
3516 lg2 = 8, x <<= 8;
|
|
|
3517
|
|
|
3518 if ((x & 0xf000) == 0)
|
|
|
3519 lg2 += 4, x <<= 4;
|
|
|
3520
|
|
|
3521 if ((x & 0xc000) == 0)
|
|
|
3522 lg2 += 2, x <<= 2;
|
|
|
3523
|
|
|
3524 if ((x & 0x8000) == 0)
|
|
|
3525 lg2 += 1, x <<= 1;
|
|
|
3526
|
|
|
3527 /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
|
|
|
3528 * value.
|
|
|
3529 */
|
|
|
3530 lg2 <<= 28;
|
|
|
3531 lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
|
|
|
3532
|
|
|
3533 /* Now we need to interpolate the factor, this requires a division by the top
|
|
|
3534 * 8 bits. Do this with maximum precision.
|
|
|
3535 */
|
|
|
3536 x = ((x << 16) + (x >> 9)) / (x >> 8);
|
|
|
3537
|
|
|
3538 /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
|
|
|
3539 * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
|
|
|
3540 * 16 bits to interpolate to get the low bits of the result. Round the
|
|
|
3541 * answer. Note that the end point values are scaled by 64 to retain overall
|
|
|
3542 * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
|
|
|
3543 * the overall scaling by 6-12. Round at every step.
|
|
|
3544 */
|
|
|
3545 x -= 1U << 24;
|
|
|
3546
|
|
|
3547 if (x <= 65536U) /* <= '257' */
|
|
|
3548 lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
|
|
|
3549
|
|
|
3550 else
|
|
|
3551 lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
|
|
|
3552
|
|
|
3553 /* Safe, because the result can't have more than 20 bits: */
|
|
|
3554 return (png_int_32)((lg2 + 2048) >> 12);
|
|
|
3555 }
|
|
|
3556
|
|
|
3557 /* The 'exp()' case must invert the above, taking a 20-bit fixed point
|
|
|
3558 * logarithmic value and returning a 16 or 8-bit number as appropriate. In
|
|
|
3559 * each case only the low 16 bits are relevant - the fraction - since the
|
|
|
3560 * integer bits (the top 4) simply determine a shift.
|
|
|
3561 *
|
|
|
3562 * The worst case is the 16-bit distinction between 65535 and 65534, this
|
|
|
3563 * requires perhaps spurious accuracty in the decoding of the logarithm to
|
|
|
3564 * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
|
|
|
3565 * of getting this accuracy in practice.
|
|
|
3566 *
|
|
|
3567 * To deal with this the following exp() function works out the exponent of the
|
|
|
3568 * frational part of the logarithm by using an accurate 32-bit value from the
|
|
|
3569 * top four fractional bits then multiplying in the remaining bits.
|
|
|
3570 */
|
|
|
3571 static const png_uint_32
|
|
|
3572 png_32bit_exp[16] =
|
|
|
3573 {
|
|
|
3574 /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
|
|
|
3575 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
|
|
|
3576 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
|
|
|
3577 2553802834U, 2445529972U, 2341847524U, 2242560872U
|
|
|
3578 };
|
|
|
3579
|
|
|
3580 /* Adjustment table; provided to explain the numbers in the code below. */
|
|
|
3581 #if 0
|
|
|
3582 for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
|
|
|
3583 11 44937.64284865548751208448
|
|
|
3584 10 45180.98734845585101160448
|
|
|
3585 9 45303.31936980687359311872
|
|
|
3586 8 45364.65110595323018870784
|
|
|
3587 7 45395.35850361789624614912
|
|
|
3588 6 45410.72259715102037508096
|
|
|
3589 5 45418.40724413220722311168
|
|
|
3590 4 45422.25021786898173001728
|
|
|
3591 3 45424.17186732298419044352
|
|
|
3592 2 45425.13273269940811464704
|
|
|
3593 1 45425.61317555035558641664
|
|
|
3594 0 45425.85339951654943850496
|
|
|
3595 #endif
|
|
|
3596
|
|
|
3597 static png_uint_32
|
|
|
3598 png_exp(png_fixed_point x)
|
|
|
3599 {
|
|
|
3600 if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
|
|
|
3601 {
|
|
|
3602 /* Obtain a 4-bit approximation */
|
|
|
3603 png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf];
|
|
|
3604
|
|
|
3605 /* Incorporate the low 12 bits - these decrease the returned value by
|
|
|
3606 * multiplying by a number less than 1 if the bit is set. The multiplier
|
|
|
3607 * is determined by the above table and the shift. Notice that the values
|
|
|
3608 * converge on 45426 and this is used to allow linear interpolation of the
|
|
|
3609 * low bits.
|
|
|
3610 */
|
|
|
3611 if (x & 0x800)
|
|
|
3612 e -= (((e >> 16) * 44938U) + 16U) >> 5;
|
|
|
3613
|
|
|
3614 if (x & 0x400)
|
|
|
3615 e -= (((e >> 16) * 45181U) + 32U) >> 6;
|
|
|
3616
|
|
|
3617 if (x & 0x200)
|
|
|
3618 e -= (((e >> 16) * 45303U) + 64U) >> 7;
|
|
|
3619
|
|
|
3620 if (x & 0x100)
|
|
|
3621 e -= (((e >> 16) * 45365U) + 128U) >> 8;
|
|
|
3622
|
|
|
3623 if (x & 0x080)
|
|
|
3624 e -= (((e >> 16) * 45395U) + 256U) >> 9;
|
|
|
3625
|
|
|
3626 if (x & 0x040)
|
|
|
3627 e -= (((e >> 16) * 45410U) + 512U) >> 10;
|
|
|
3628
|
|
|
3629 /* And handle the low 6 bits in a single block. */
|
|
|
3630 e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
|
|
|
3631
|
|
|
3632 /* Handle the upper bits of x. */
|
|
|
3633 e >>= x >> 16;
|
|
|
3634 return e;
|
|
|
3635 }
|
|
|
3636
|
|
|
3637 /* Check for overflow */
|
|
|
3638 if (x <= 0)
|
|
|
3639 return png_32bit_exp[0];
|
|
|
3640
|
|
|
3641 /* Else underflow */
|
|
|
3642 return 0;
|
|
|
3643 }
|
|
|
3644
|
|
|
3645 static png_byte
|
|
|
3646 png_exp8bit(png_fixed_point lg2)
|
|
|
3647 {
|
|
|
3648 /* Get a 32-bit value: */
|
|
|
3649 png_uint_32 x = png_exp(lg2);
|
|
|
3650
|
|
|
3651 /* Convert the 32-bit value to 0..255 by multiplying by 256-1, note that the
|
|
|
3652 * second, rounding, step can't overflow because of the first, subtraction,
|
|
|
3653 * step.
|
|
|
3654 */
|
|
|
3655 x -= x >> 8;
|
|
|
3656 return (png_byte)((x + 0x7fffffU) >> 24);
|
|
|
3657 }
|
|
|
3658
|
|
|
3659 #ifdef PNG_16BIT_SUPPORTED
|
|
|
3660 static png_uint_16
|
|
|
3661 png_exp16bit(png_fixed_point lg2)
|
|
|
3662 {
|
|
|
3663 /* Get a 32-bit value: */
|
|
|
3664 png_uint_32 x = png_exp(lg2);
|
|
|
3665
|
|
|
3666 /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
|
|
|
3667 x -= x >> 16;
|
|
|
3668 return (png_uint_16)((x + 32767U) >> 16);
|
|
|
3669 }
|
|
|
3670 #endif /* 16BIT */
|
|
|
3671 #endif /* FLOATING_ARITHMETIC */
|
|
|
3672
|
|
|
3673 png_byte
|
|
|
3674 png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
|
|
|
3675 {
|
|
|
3676 if (value > 0 && value < 255)
|
|
|
3677 {
|
|
|
3678 # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3679 double r = floor(255*pow(value/255.,gamma_val*.00001)+.5);
|
|
|
3680 return (png_byte)r;
|
|
|
3681 # else
|
|
|
3682 png_int_32 lg2 = png_log8bit(value);
|
|
|
3683 png_fixed_point res;
|
|
|
3684
|
|
|
3685 if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
|
|
|
3686 return png_exp8bit(res);
|
|
|
3687
|
|
|
3688 /* Overflow. */
|
|
|
3689 value = 0;
|
|
|
3690 # endif
|
|
|
3691 }
|
|
|
3692
|
|
|
3693 return (png_byte)value;
|
|
|
3694 }
|
|
|
3695
|
|
|
3696 #ifdef PNG_16BIT_SUPPORTED
|
|
|
3697 png_uint_16
|
|
|
3698 png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
|
|
|
3699 {
|
|
|
3700 if (value > 0 && value < 65535)
|
|
|
3701 {
|
|
|
3702 # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3703 double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5);
|
|
|
3704 return (png_uint_16)r;
|
|
|
3705 # else
|
|
|
3706 png_int_32 lg2 = png_log16bit(value);
|
|
|
3707 png_fixed_point res;
|
|
|
3708
|
|
|
3709 if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1))
|
|
|
3710 return png_exp16bit(res);
|
|
|
3711
|
|
|
3712 /* Overflow. */
|
|
|
3713 value = 0;
|
|
|
3714 # endif
|
|
|
3715 }
|
|
|
3716
|
|
|
3717 return (png_uint_16)value;
|
|
|
3718 }
|
|
|
3719 #endif /* 16BIT */
|
|
|
3720
|
|
|
3721 /* This does the right thing based on the bit_depth field of the
|
|
|
3722 * png_struct, interpreting values as 8-bit or 16-bit. While the result
|
|
|
3723 * is nominally a 16-bit value if bit depth is 8 then the result is
|
|
|
3724 * 8-bit (as are the arguments.)
|
|
|
3725 */
|
|
|
3726 png_uint_16 /* PRIVATE */
|
|
|
3727 png_gamma_correct(png_structrp png_ptr, unsigned int value,
|
|
|
3728 png_fixed_point gamma_val)
|
|
|
3729 {
|
|
|
3730 if (png_ptr->bit_depth == 8)
|
|
|
3731 return png_gamma_8bit_correct(value, gamma_val);
|
|
|
3732
|
|
|
3733 #ifdef PNG_16BIT_SUPPORTED
|
|
|
3734 else
|
|
|
3735 return png_gamma_16bit_correct(value, gamma_val);
|
|
|
3736 #else
|
|
|
3737 /* should not reach this */
|
|
|
3738 return 0;
|
|
|
3739 #endif /* 16BIT */
|
|
|
3740 }
|
|
|
3741
|
|
|
3742 #ifdef PNG_16BIT_SUPPORTED
|
|
|
3743 /* Internal function to build a single 16-bit table - the table consists of
|
|
|
3744 * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
|
|
|
3745 * to shift the input values right (or 16-number_of_signifiant_bits).
|
|
|
3746 *
|
|
|
3747 * The caller is responsible for ensuring that the table gets cleaned up on
|
|
|
3748 * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
|
|
|
3749 * should be somewhere that will be cleaned.
|
|
|
3750 */
|
|
|
3751 static void
|
|
|
3752 png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
|
|
|
3753 PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
|
|
|
3754 {
|
|
|
3755 /* Various values derived from 'shift': */
|
|
|
3756 PNG_CONST unsigned int num = 1U << (8U - shift);
|
|
|
3757 PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
|
|
|
3758 PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
|
|
|
3759 unsigned int i;
|
|
|
3760
|
|
|
3761 png_uint_16pp table = *ptable =
|
|
|
3762 (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
|
|
|
3763
|
|
|
3764 for (i = 0; i < num; i++)
|
|
|
3765 {
|
|
|
3766 png_uint_16p sub_table = table[i] =
|
|
|
3767 (png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
|
|
|
3768
|
|
|
3769 /* The 'threshold' test is repeated here because it can arise for one of
|
|
|
3770 * the 16-bit tables even if the others don't hit it.
|
|
|
3771 */
|
|
|
3772 if (png_gamma_significant(gamma_val))
|
|
|
3773 {
|
|
|
3774 /* The old code would overflow at the end and this would cause the
|
|
|
3775 * 'pow' function to return a result >1, resulting in an
|
|
|
3776 * arithmetic error. This code follows the spec exactly; ig is
|
|
|
3777 * the recovered input sample, it always has 8-16 bits.
|
|
|
3778 *
|
|
|
3779 * We want input * 65535/max, rounded, the arithmetic fits in 32
|
|
|
3780 * bits (unsigned) so long as max <= 32767.
|
|
|
3781 */
|
|
|
3782 unsigned int j;
|
|
|
3783 for (j = 0; j < 256; j++)
|
|
|
3784 {
|
|
|
3785 png_uint_32 ig = (j << (8-shift)) + i;
|
|
|
3786 # ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
|
|
|
3787 /* Inline the 'max' scaling operation: */
|
|
|
3788 double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5);
|
|
|
3789 sub_table[j] = (png_uint_16)d;
|
|
|
3790 # else
|
|
|
3791 if (shift)
|
|
|
3792 ig = (ig * 65535U + max_by_2)/max;
|
|
|
3793
|
|
|
3794 sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
|
|
|
3795 # endif
|
|
|
3796 }
|
|
|
3797 }
|
|
|
3798 else
|
|
|
3799 {
|
|
|
3800 /* We must still build a table, but do it the fast way. */
|
|
|
3801 unsigned int j;
|
|
|
3802
|
|
|
3803 for (j = 0; j < 256; j++)
|
|
|
3804 {
|
|
|
3805 png_uint_32 ig = (j << (8-shift)) + i;
|
|
|
3806
|
|
|
3807 if (shift)
|
|
|
3808 ig = (ig * 65535U + max_by_2)/max;
|
|
|
3809
|
|
|
3810 sub_table[j] = (png_uint_16)ig;
|
|
|
3811 }
|
|
|
3812 }
|
|
|
3813 }
|
|
|
3814 }
|
|
|
3815
|
|
|
3816 /* NOTE: this function expects the *inverse* of the overall gamma transformation
|
|
|
3817 * required.
|
|
|
3818 */
|
|
|
3819 static void
|
|
|
3820 png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
|
|
|
3821 PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
|
|
|
3822 {
|
|
|
3823 PNG_CONST unsigned int num = 1U << (8U - shift);
|
|
|
3824 PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
|
|
|
3825 unsigned int i;
|
|
|
3826 png_uint_32 last;
|
|
|
3827
|
|
|
3828 png_uint_16pp table = *ptable =
|
|
|
3829 (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
|
|
|
3830
|
|
|
3831 /* 'num' is the number of tables and also the number of low bits of low
|
|
|
3832 * bits of the input 16-bit value used to select a table. Each table is
|
|
|
3833 * itself index by the high 8 bits of the value.
|
|
|
3834 */
|
|
|
3835 for (i = 0; i < num; i++)
|
|
|
3836 table[i] = (png_uint_16p)png_malloc(png_ptr,
|
|
|
3837 256 * (sizeof (png_uint_16)));
|
|
|
3838
|
|
|
3839 /* 'gamma_val' is set to the reciprocal of the value calculated above, so
|
|
|
3840 * pow(out,g) is an *input* value. 'last' is the last input value set.
|
|
|
3841 *
|
|
|
3842 * In the loop 'i' is used to find output values. Since the output is
|
|
|
3843 * 8-bit there are only 256 possible values. The tables are set up to
|
|
|
3844 * select the closest possible output value for each input by finding
|
|
|
3845 * the input value at the boundary between each pair of output values
|
|
|
3846 * and filling the table up to that boundary with the lower output
|
|
|
3847 * value.
|
|
|
3848 *
|
|
|
3849 * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
|
|
|
3850 * values the code below uses a 16-bit value in i; the values start at
|
|
|
3851 * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
|
|
|
3852 * entries are filled with 255). Start i at 128 and fill all 'last'
|
|
|
3853 * table entries <= 'max'
|
|
|
3854 */
|
|
|
3855 last = 0;
|
|
|
3856 for (i = 0; i < 255; ++i) /* 8-bit output value */
|
|
|
3857 {
|
|
|
3858 /* Find the corresponding maximum input value */
|
|
|
3859 png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
|
|
|
3860
|
|
|
3861 /* Find the boundary value in 16 bits: */
|
|
|
3862 png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
|
|
|
3863
|
|
|
3864 /* Adjust (round) to (16-shift) bits: */
|
|
|
3865 bound = (bound * max + 32768U)/65535U + 1U;
|
|
|
3866
|
|
|
3867 while (last < bound)
|
|
|
3868 {
|
|
|
3869 table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
|
|
|
3870 last++;
|
|
|
3871 }
|
|
|
3872 }
|
|
|
3873
|
|
|
3874 /* And fill in the final entries. */
|
|
|
3875 while (last < (num << 8))
|
|
|
3876 {
|
|
|
3877 table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
|
|
|
3878 last++;
|
|
|
3879 }
|
|
|
3880 }
|
|
|
3881 #endif /* 16BIT */
|
|
|
3882
|
|
|
3883 /* Build a single 8-bit table: same as the 16-bit case but much simpler (and
|
|
|
3884 * typically much faster). Note that libpng currently does no sBIT processing
|
|
|
3885 * (apparently contrary to the spec) so a 256 entry table is always generated.
|
|
|
3886 */
|
|
|
3887 static void
|
|
|
3888 png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
|
|
|
3889 PNG_CONST png_fixed_point gamma_val)
|
|
|
3890 {
|
|
|
3891 unsigned int i;
|
|
|
3892 png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
|
|
|
3893
|
|
|
3894 if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++)
|
|
|
3895 table[i] = png_gamma_8bit_correct(i, gamma_val);
|
|
|
3896
|
|
|
3897 else for (i=0; i<256; ++i)
|
|
|
3898 table[i] = (png_byte)i;
|
|
|
3899 }
|
|
|
3900
|
|
|
3901 /* Used from png_read_destroy and below to release the memory used by the gamma
|
|
|
3902 * tables.
|
|
|
3903 */
|
|
|
3904 void /* PRIVATE */
|
|
|
3905 png_destroy_gamma_table(png_structrp png_ptr)
|
|
|
3906 {
|
|
|
3907 png_free(png_ptr, png_ptr->gamma_table);
|
|
|
3908 png_ptr->gamma_table = NULL;
|
|
|
3909
|
|
|
3910 #ifdef PNG_16BIT_SUPPORTED
|
|
|
3911 if (png_ptr->gamma_16_table != NULL)
|
|
|
3912 {
|
|
|
3913 int i;
|
|
|
3914 int istop = (1 << (8 - png_ptr->gamma_shift));
|
|
|
3915 for (i = 0; i < istop; i++)
|
|
|
3916 {
|
|
|
3917 png_free(png_ptr, png_ptr->gamma_16_table[i]);
|
|
|
3918 }
|
|
|
3919 png_free(png_ptr, png_ptr->gamma_16_table);
|
|
|
3920 png_ptr->gamma_16_table = NULL;
|
|
|
3921 }
|
|
|
3922 #endif /* 16BIT */
|
|
|
3923
|
|
|
3924 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
|
3925 defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
|
|
3926 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
|
|
3927 png_free(png_ptr, png_ptr->gamma_from_1);
|
|
|
3928 png_ptr->gamma_from_1 = NULL;
|
|
|
3929 png_free(png_ptr, png_ptr->gamma_to_1);
|
|
|
3930 png_ptr->gamma_to_1 = NULL;
|
|
|
3931
|
|
|
3932 #ifdef PNG_16BIT_SUPPORTED
|
|
|
3933 if (png_ptr->gamma_16_from_1 != NULL)
|
|
|
3934 {
|
|
|
3935 int i;
|
|
|
3936 int istop = (1 << (8 - png_ptr->gamma_shift));
|
|
|
3937 for (i = 0; i < istop; i++)
|
|
|
3938 {
|
|
|
3939 png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
|
|
|
3940 }
|
|
|
3941 png_free(png_ptr, png_ptr->gamma_16_from_1);
|
|
|
3942 png_ptr->gamma_16_from_1 = NULL;
|
|
|
3943 }
|
|
|
3944 if (png_ptr->gamma_16_to_1 != NULL)
|
|
|
3945 {
|
|
|
3946 int i;
|
|
|
3947 int istop = (1 << (8 - png_ptr->gamma_shift));
|
|
|
3948 for (i = 0; i < istop; i++)
|
|
|
3949 {
|
|
|
3950 png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
|
|
|
3951 }
|
|
|
3952 png_free(png_ptr, png_ptr->gamma_16_to_1);
|
|
|
3953 png_ptr->gamma_16_to_1 = NULL;
|
|
|
3954 }
|
|
|
3955 #endif /* 16BIT */
|
|
|
3956 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
|
3957 }
|
|
|
3958
|
|
|
3959 /* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
|
|
|
3960 * tables, we don't make a full table if we are reducing to 8-bit in
|
|
|
3961 * the future. Note also how the gamma_16 tables are segmented so that
|
|
|
3962 * we don't need to allocate > 64K chunks for a full 16-bit table.
|
|
|
3963 */
|
|
|
3964 void /* PRIVATE */
|
|
|
3965 png_build_gamma_table(png_structrp png_ptr, int bit_depth)
|
|
|
3966 {
|
|
|
3967 png_debug(1, "in png_build_gamma_table");
|
|
|
3968
|
|
|
3969 /* Remove any existing table; this copes with multiple calls to
|
|
|
3970 * png_read_update_info. The warning is because building the gamma tables
|
|
|
3971 * multiple times is a performance hit - it's harmless but the ability to call
|
|
|
3972 * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
|
|
|
3973 * to warn if the app introduces such a hit.
|
|
|
3974 */
|
|
|
3975 if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
|
|
|
3976 {
|
|
|
3977 png_warning(png_ptr, "gamma table being rebuilt");
|
|
|
3978 png_destroy_gamma_table(png_ptr);
|
|
|
3979 }
|
|
|
3980
|
|
|
3981 if (bit_depth <= 8)
|
|
|
3982 {
|
|
|
3983 png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
|
|
|
3984 png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
|
|
|
3985 png_ptr->screen_gamma) : PNG_FP_1);
|
|
|
3986
|
|
|
3987 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
|
3988 defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
|
|
3989 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
|
|
3990 if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
|
|
|
3991 {
|
|
|
3992 png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
|
|
|
3993 png_reciprocal(png_ptr->colorspace.gamma));
|
|
|
3994
|
|
|
3995 png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
|
|
|
3996 png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
|
|
|
3997 png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
|
|
|
3998 }
|
|
|
3999 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
|
4000 }
|
|
|
4001 #ifdef PNG_16BIT_SUPPORTED
|
|
|
4002 else
|
|
|
4003 {
|
|
|
4004 png_byte shift, sig_bit;
|
|
|
4005
|
|
|
4006 if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
|
|
|
4007 {
|
|
|
4008 sig_bit = png_ptr->sig_bit.red;
|
|
|
4009
|
|
|
4010 if (png_ptr->sig_bit.green > sig_bit)
|
|
|
4011 sig_bit = png_ptr->sig_bit.green;
|
|
|
4012
|
|
|
4013 if (png_ptr->sig_bit.blue > sig_bit)
|
|
|
4014 sig_bit = png_ptr->sig_bit.blue;
|
|
|
4015 }
|
|
|
4016 else
|
|
|
4017 sig_bit = png_ptr->sig_bit.gray;
|
|
|
4018
|
|
|
4019 /* 16-bit gamma code uses this equation:
|
|
|
4020 *
|
|
|
4021 * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
|
|
|
4022 *
|
|
|
4023 * Where 'iv' is the input color value and 'ov' is the output value -
|
|
|
4024 * pow(iv, gamma).
|
|
|
4025 *
|
|
|
4026 * Thus the gamma table consists of up to 256 256 entry tables. The table
|
|
|
4027 * is selected by the (8-gamma_shift) most significant of the low 8 bits of
|
|
|
4028 * the color value then indexed by the upper 8 bits:
|
|
|
4029 *
|
|
|
4030 * table[low bits][high 8 bits]
|
|
|
4031 *
|
|
|
4032 * So the table 'n' corresponds to all those 'iv' of:
|
|
|
4033 *
|
|
|
4034 * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
|
|
|
4035 *
|
|
|
4036 */
|
|
|
4037 if (sig_bit > 0 && sig_bit < 16U)
|
|
|
4038 shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */
|
|
|
4039
|
|
|
4040 else
|
|
|
4041 shift = 0; /* keep all 16 bits */
|
|
|
4042
|
|
|
4043 if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
|
|
|
4044 {
|
|
|
4045 /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
|
|
|
4046 * the significant bits in the *input* when the output will
|
|
|
4047 * eventually be 8 bits. By default it is 11.
|
|
|
4048 */
|
|
|
4049 if (shift < (16U - PNG_MAX_GAMMA_8))
|
|
|
4050 shift = (16U - PNG_MAX_GAMMA_8);
|
|
|
4051 }
|
|
|
4052
|
|
|
4053 if (shift > 8U)
|
|
|
4054 shift = 8U; /* Guarantees at least one table! */
|
|
|
4055
|
|
|
4056 png_ptr->gamma_shift = shift;
|
|
|
4057
|
|
|
4058 /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
|
|
|
4059 * PNG_COMPOSE). This effectively smashed the background calculation for
|
|
|
4060 * 16-bit output because the 8-bit table assumes the result will be reduced
|
|
|
4061 * to 8 bits.
|
|
|
4062 */
|
|
|
4063 if (png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8))
|
|
|
4064 png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
|
|
4065 png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
|
|
|
4066 png_ptr->screen_gamma) : PNG_FP_1);
|
|
|
4067
|
|
|
4068 else
|
|
|
4069 png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
|
|
|
4070 png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
|
|
|
4071 png_ptr->screen_gamma) : PNG_FP_1);
|
|
|
4072
|
|
|
4073 #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
|
|
|
4074 defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
|
|
|
4075 defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
|
|
|
4076 if (png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY))
|
|
|
4077 {
|
|
|
4078 png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
|
|
|
4079 png_reciprocal(png_ptr->colorspace.gamma));
|
|
|
4080
|
|
|
4081 /* Notice that the '16 from 1' table should be full precision, however
|
|
|
4082 * the lookup on this table still uses gamma_shift, so it can't be.
|
|
|
4083 * TODO: fix this.
|
|
|
4084 */
|
|
|
4085 png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
|
|
|
4086 png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
|
|
|
4087 png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
|
|
|
4088 }
|
|
|
4089 #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
|
|
|
4090 }
|
|
|
4091 #endif /* 16BIT */
|
|
|
4092 }
|
|
|
4093 #endif /* READ_GAMMA */
|
|
|
4094
|
|
|
4095 /* HARDWARE OPTION SUPPORT */
|
|
|
4096 #ifdef PNG_SET_OPTION_SUPPORTED
|
|
|
4097 int PNGAPI
|
|
|
4098 png_set_option(png_structrp png_ptr, int option, int onoff)
|
|
|
4099 {
|
|
|
4100 if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
|
|
|
4101 (option & 1) == 0)
|
|
|
4102 {
|
|
|
4103 int mask = 3 << option;
|
|
|
4104 int setting = (2 + (onoff != 0)) << option;
|
|
|
4105 int current = png_ptr->options;
|
|
|
4106
|
|
|
4107 png_ptr->options = (png_byte)((current & ~mask) | setting);
|
|
|
4108
|
|
|
4109 return (current & mask) >> option;
|
|
|
4110 }
|
|
|
4111
|
|
|
4112 return PNG_OPTION_INVALID;
|
|
|
4113 }
|
|
|
4114 #endif
|
|
|
4115
|
|
|
4116 /* sRGB support */
|
|
|
4117 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
|
|
|
4118 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
|
|
|
4119 /* sRGB conversion tables; these are machine generated with the code in
|
|
|
4120 * contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
|
|
|
4121 * specification (see the article at http://en.wikipedia.org/wiki/SRGB)
|
|
|
4122 * is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
|
|
|
4123 * The sRGB to linear table is exact (to the nearest 16 bit linear fraction).
|
|
|
4124 * The inverse (linear to sRGB) table has accuracies as follows:
|
|
|
4125 *
|
|
|
4126 * For all possible (255*65535+1) input values:
|
|
|
4127 *
|
|
|
4128 * error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
|
|
|
4129 *
|
|
|
4130 * For the input values corresponding to the 65536 16-bit values:
|
|
|
4131 *
|
|
|
4132 * error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
|
|
|
4133 *
|
|
|
4134 * In all cases the inexact readings are off by one.
|
|
|
4135 */
|
|
|
4136
|
|
|
4137 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
|
|
4138 /* The convert-to-sRGB table is only currently required for read. */
|
|
|
4139 const png_uint_16 png_sRGB_table[256] =
|
|
|
4140 {
|
|
|
4141 0,20,40,60,80,99,119,139,
|
|
|
4142 159,179,199,219,241,264,288,313,
|
|
|
4143 340,367,396,427,458,491,526,562,
|
|
|
4144 599,637,677,718,761,805,851,898,
|
|
|
4145 947,997,1048,1101,1156,1212,1270,1330,
|
|
|
4146 1391,1453,1517,1583,1651,1720,1790,1863,
|
|
|
4147 1937,2013,2090,2170,2250,2333,2418,2504,
|
|
|
4148 2592,2681,2773,2866,2961,3058,3157,3258,
|
|
|
4149 3360,3464,3570,3678,3788,3900,4014,4129,
|
|
|
4150 4247,4366,4488,4611,4736,4864,4993,5124,
|
|
|
4151 5257,5392,5530,5669,5810,5953,6099,6246,
|
|
|
4152 6395,6547,6700,6856,7014,7174,7335,7500,
|
|
|
4153 7666,7834,8004,8177,8352,8528,8708,8889,
|
|
|
4154 9072,9258,9445,9635,9828,10022,10219,10417,
|
|
|
4155 10619,10822,11028,11235,11446,11658,11873,12090,
|
|
|
4156 12309,12530,12754,12980,13209,13440,13673,13909,
|
|
|
4157 14146,14387,14629,14874,15122,15371,15623,15878,
|
|
|
4158 16135,16394,16656,16920,17187,17456,17727,18001,
|
|
|
4159 18277,18556,18837,19121,19407,19696,19987,20281,
|
|
|
4160 20577,20876,21177,21481,21787,22096,22407,22721,
|
|
|
4161 23038,23357,23678,24002,24329,24658,24990,25325,
|
|
|
4162 25662,26001,26344,26688,27036,27386,27739,28094,
|
|
|
4163 28452,28813,29176,29542,29911,30282,30656,31033,
|
|
|
4164 31412,31794,32179,32567,32957,33350,33745,34143,
|
|
|
4165 34544,34948,35355,35764,36176,36591,37008,37429,
|
|
|
4166 37852,38278,38706,39138,39572,40009,40449,40891,
|
|
|
4167 41337,41785,42236,42690,43147,43606,44069,44534,
|
|
|
4168 45002,45473,45947,46423,46903,47385,47871,48359,
|
|
|
4169 48850,49344,49841,50341,50844,51349,51858,52369,
|
|
|
4170 52884,53401,53921,54445,54971,55500,56032,56567,
|
|
|
4171 57105,57646,58190,58737,59287,59840,60396,60955,
|
|
|
4172 61517,62082,62650,63221,63795,64372,64952,65535
|
|
|
4173 };
|
|
|
4174
|
|
|
4175 #endif /* simplified read only */
|
|
|
4176
|
|
|
4177 /* The base/delta tables are required for both read and write (but currently
|
|
|
4178 * only the simplified versions.)
|
|
|
4179 */
|
|
|
4180 const png_uint_16 png_sRGB_base[512] =
|
|
|
4181 {
|
|
|
4182 128,1782,3383,4644,5675,6564,7357,8074,
|
|
|
4183 8732,9346,9921,10463,10977,11466,11935,12384,
|
|
|
4184 12816,13233,13634,14024,14402,14769,15125,15473,
|
|
|
4185 15812,16142,16466,16781,17090,17393,17690,17981,
|
|
|
4186 18266,18546,18822,19093,19359,19621,19879,20133,
|
|
|
4187 20383,20630,20873,21113,21349,21583,21813,22041,
|
|
|
4188 22265,22487,22707,22923,23138,23350,23559,23767,
|
|
|
4189 23972,24175,24376,24575,24772,24967,25160,25352,
|
|
|
4190 25542,25730,25916,26101,26284,26465,26645,26823,
|
|
|
4191 27000,27176,27350,27523,27695,27865,28034,28201,
|
|
|
4192 28368,28533,28697,28860,29021,29182,29341,29500,
|
|
|
4193 29657,29813,29969,30123,30276,30429,30580,30730,
|
|
|
4194 30880,31028,31176,31323,31469,31614,31758,31902,
|
|
|
4195 32045,32186,32327,32468,32607,32746,32884,33021,
|
|
|
4196 33158,33294,33429,33564,33697,33831,33963,34095,
|
|
|
4197 34226,34357,34486,34616,34744,34873,35000,35127,
|
|
|
4198 35253,35379,35504,35629,35753,35876,35999,36122,
|
|
|
4199 36244,36365,36486,36606,36726,36845,36964,37083,
|
|
|
4200 37201,37318,37435,37551,37668,37783,37898,38013,
|
|
|
4201 38127,38241,38354,38467,38580,38692,38803,38915,
|
|
|
4202 39026,39136,39246,39356,39465,39574,39682,39790,
|
|
|
4203 39898,40005,40112,40219,40325,40431,40537,40642,
|
|
|
4204 40747,40851,40955,41059,41163,41266,41369,41471,
|
|
|
4205 41573,41675,41777,41878,41979,42079,42179,42279,
|
|
|
4206 42379,42478,42577,42676,42775,42873,42971,43068,
|
|
|
4207 43165,43262,43359,43456,43552,43648,43743,43839,
|
|
|
4208 43934,44028,44123,44217,44311,44405,44499,44592,
|
|
|
4209 44685,44778,44870,44962,45054,45146,45238,45329,
|
|
|
4210 45420,45511,45601,45692,45782,45872,45961,46051,
|
|
|
4211 46140,46229,46318,46406,46494,46583,46670,46758,
|
|
|
4212 46846,46933,47020,47107,47193,47280,47366,47452,
|
|
|
4213 47538,47623,47709,47794,47879,47964,48048,48133,
|
|
|
4214 48217,48301,48385,48468,48552,48635,48718,48801,
|
|
|
4215 48884,48966,49048,49131,49213,49294,49376,49458,
|
|
|
4216 49539,49620,49701,49782,49862,49943,50023,50103,
|
|
|
4217 50183,50263,50342,50422,50501,50580,50659,50738,
|
|
|
4218 50816,50895,50973,51051,51129,51207,51285,51362,
|
|
|
4219 51439,51517,51594,51671,51747,51824,51900,51977,
|
|
|
4220 52053,52129,52205,52280,52356,52432,52507,52582,
|
|
|
4221 52657,52732,52807,52881,52956,53030,53104,53178,
|
|
|
4222 53252,53326,53400,53473,53546,53620,53693,53766,
|
|
|
4223 53839,53911,53984,54056,54129,54201,54273,54345,
|
|
|
4224 54417,54489,54560,54632,54703,54774,54845,54916,
|
|
|
4225 54987,55058,55129,55199,55269,55340,55410,55480,
|
|
|
4226 55550,55620,55689,55759,55828,55898,55967,56036,
|
|
|
4227 56105,56174,56243,56311,56380,56448,56517,56585,
|
|
|
4228 56653,56721,56789,56857,56924,56992,57059,57127,
|
|
|
4229 57194,57261,57328,57395,57462,57529,57595,57662,
|
|
|
4230 57728,57795,57861,57927,57993,58059,58125,58191,
|
|
|
4231 58256,58322,58387,58453,58518,58583,58648,58713,
|
|
|
4232 58778,58843,58908,58972,59037,59101,59165,59230,
|
|
|
4233 59294,59358,59422,59486,59549,59613,59677,59740,
|
|
|
4234 59804,59867,59930,59993,60056,60119,60182,60245,
|
|
|
4235 60308,60370,60433,60495,60558,60620,60682,60744,
|
|
|
4236 60806,60868,60930,60992,61054,61115,61177,61238,
|
|
|
4237 61300,61361,61422,61483,61544,61605,61666,61727,
|
|
|
4238 61788,61848,61909,61969,62030,62090,62150,62211,
|
|
|
4239 62271,62331,62391,62450,62510,62570,62630,62689,
|
|
|
4240 62749,62808,62867,62927,62986,63045,63104,63163,
|
|
|
4241 63222,63281,63340,63398,63457,63515,63574,63632,
|
|
|
4242 63691,63749,63807,63865,63923,63981,64039,64097,
|
|
|
4243 64155,64212,64270,64328,64385,64443,64500,64557,
|
|
|
4244 64614,64672,64729,64786,64843,64900,64956,65013,
|
|
|
4245 65070,65126,65183,65239,65296,65352,65409,65465
|
|
|
4246 };
|
|
|
4247
|
|
|
4248 const png_byte png_sRGB_delta[512] =
|
|
|
4249 {
|
|
|
4250 207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
|
|
|
4251 52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
|
|
|
4252 35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
|
|
|
4253 28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
|
|
|
4254 23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
|
|
|
4255 21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
|
|
|
4256 19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
|
|
|
4257 17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
|
|
|
4258 16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
|
|
|
4259 15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
|
|
|
4260 14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
|
|
|
4261 13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
|
|
|
4262 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
|
|
|
4263 12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
|
|
|
4264 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
|
|
|
4265 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
|
|
|
4266 11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
|
|
4267 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
|
|
4268 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
|
|
|
4269 10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
|
4270 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
|
4271 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
|
4272 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
|
|
|
4273 9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
|
4274 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
|
4275 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
|
4276 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
|
4277 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
|
4278 8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
|
|
|
4279 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
|
|
4280 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
|
|
4281 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
|
|
|
4282 };
|
|
|
4283 #endif /* SIMPLIFIED READ/WRITE sRGB support */
|
|
|
4284
|
|
|
4285 /* SIMPLIFIED READ/WRITE SUPPORT */
|
|
|
4286 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
|
|
|
4287 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
|
|
|
4288 static int
|
|
|
4289 png_image_free_function(png_voidp argument)
|
|
|
4290 {
|
|
|
4291 png_imagep image = png_voidcast(png_imagep, argument);
|
|
|
4292 png_controlp cp = image->opaque;
|
|
|
4293 png_control c;
|
|
|
4294
|
|
|
4295 /* Double check that we have a png_ptr - it should be impossible to get here
|
|
|
4296 * without one.
|
|
|
4297 */
|
|
|
4298 if (cp->png_ptr == NULL)
|
|
|
4299 return 0;
|
|
|
4300
|
|
|
4301 /* First free any data held in the control structure. */
|
|
|
4302 # ifdef PNG_STDIO_SUPPORTED
|
|
|
4303 if (cp->owned_file)
|
|
|
4304 {
|
|
|
4305 FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
|
|
|
4306 cp->owned_file = 0;
|
|
|
4307
|
|
|
4308 /* Ignore errors here. */
|
|
|
4309 if (fp != NULL)
|
|
|
4310 {
|
|
|
4311 cp->png_ptr->io_ptr = NULL;
|
|
|
4312 (void)fclose(fp);
|
|
|
4313 }
|
|
|
4314 }
|
|
|
4315 # endif
|
|
|
4316
|
|
|
4317 /* Copy the control structure so that the original, allocated, version can be
|
|
|
4318 * safely freed. Notice that a png_error here stops the remainder of the
|
|
|
4319 * cleanup, but this is probably fine because that would indicate bad memory
|
|
|
4320 * problems anyway.
|
|
|
4321 */
|
|
|
4322 c = *cp;
|
|
|
4323 image->opaque = &c;
|
|
|
4324 png_free(c.png_ptr, cp);
|
|
|
4325
|
|
|
4326 /* Then the structures, calling the correct API. */
|
|
|
4327 if (c.for_write)
|
|
|
4328 {
|
|
|
4329 # ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
|
|
|
4330 png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
|
|
|
4331 # else
|
|
|
4332 png_error(c.png_ptr, "simplified write not supported");
|
|
|
4333 # endif
|
|
|
4334 }
|
|
|
4335 else
|
|
|
4336 {
|
|
|
4337 # ifdef PNG_SIMPLIFIED_READ_SUPPORTED
|
|
|
4338 png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
|
|
|
4339 # else
|
|
|
4340 png_error(c.png_ptr, "simplified read not supported");
|
|
|
4341 # endif
|
|
|
4342 }
|
|
|
4343
|
|
|
4344 /* Success. */
|
|
|
4345 return 1;
|
|
|
4346 }
|
|
|
4347
|
|
|
4348 void PNGAPI
|
|
|
4349 png_image_free(png_imagep image)
|
|
|
4350 {
|
|
|
4351 /* Safely call the real function, but only if doing so is safe at this point
|
|
|
4352 * (if not inside an error handling context). Otherwise assume
|
|
|
4353 * png_safe_execute will call this API after the return.
|
|
|
4354 */
|
|
|
4355 if (image != NULL && image->opaque != NULL &&
|
|
|
4356 image->opaque->error_buf == NULL)
|
|
|
4357 {
|
|
|
4358 /* Ignore errors here: */
|
|
|
4359 (void)png_safe_execute(image, png_image_free_function, image);
|
|
|
4360 image->opaque = NULL;
|
|
|
4361 }
|
|
|
4362 }
|
|
|
4363
|
|
|
4364 int /* PRIVATE */
|
|
|
4365 png_image_error(png_imagep image, png_const_charp error_message)
|
|
|
4366 {
|
|
|
4367 /* Utility to log an error. */
|
|
|
4368 png_safecat(image->message, (sizeof image->message), 0, error_message);
|
|
|
4369 image->warning_or_error |= PNG_IMAGE_ERROR;
|
|
|
4370 png_image_free(image);
|
|
|
4371 return 0;
|
|
|
4372 }
|
|
|
4373
|
|
|
4374 #endif /* SIMPLIFIED READ/WRITE */
|
|
|
4375 #endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */
|
