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1242
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1 /*
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2 LodePNG version 20230410
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3
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4 Copyright (c) 2005-2023 Lode Vandevenne
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5
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6 This software is provided 'as-is', without any express or implied
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7 warranty. In no event will the authors be held liable for any damages
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8 arising from the use of this software.
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9
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10 Permission is granted to anyone to use this software for any purpose,
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11 including commercial applications, and to alter it and redistribute it
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12 freely, subject to the following restrictions:
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13
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14 1. The origin of this software must not be misrepresented; you must not
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15 claim that you wrote the original software. If you use this software
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16 in a product, an acknowledgment in the product documentation would be
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17 appreciated but is not required.
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18
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19 2. Altered source versions must be plainly marked as such, and must not be
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20 misrepresented as being the original software.
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21
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22 3. This notice may not be removed or altered from any source
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23 distribution.
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24 */
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25
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26 #ifndef LODEPNG_H
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27 #define LODEPNG_H
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28
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29 #include <string.h> /*for size_t*/
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30
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31 extern const char* LODEPNG_VERSION_STRING;
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32
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33 /*
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34 The following #defines are used to create code sections. They can be disabled
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35 to disable code sections, which can give faster compile time and smaller binary.
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36 The "NO_COMPILE" defines are designed to be used to pass as defines to the
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37 compiler command to disable them without modifying this header, e.g.
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38 -DLODEPNG_NO_COMPILE_ZLIB for gcc or clang.
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39 */
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40 /*deflate & zlib. If disabled, you must specify alternative zlib functions in
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41 the custom_zlib field of the compress and decompress settings*/
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42 #ifndef LODEPNG_NO_COMPILE_ZLIB
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43 /*pass -DLODEPNG_NO_COMPILE_ZLIB to the compiler to disable this, or comment out LODEPNG_COMPILE_ZLIB below*/
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44 #define LODEPNG_COMPILE_ZLIB
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45 #endif
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46
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47 /*png encoder and png decoder*/
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48 #ifndef LODEPNG_NO_COMPILE_PNG
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49 /*pass -DLODEPNG_NO_COMPILE_PNG to the compiler to disable this, or comment out LODEPNG_COMPILE_PNG below*/
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50 #define LODEPNG_COMPILE_PNG
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51 #endif
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52
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53 /*deflate&zlib decoder and png decoder*/
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54 #ifndef LODEPNG_NO_COMPILE_DECODER
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55 /*pass -DLODEPNG_NO_COMPILE_DECODER to the compiler to disable this, or comment out LODEPNG_COMPILE_DECODER below*/
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56 #define LODEPNG_COMPILE_DECODER
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57 #endif
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58
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59 /*deflate&zlib encoder and png encoder*/
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60 #ifndef LODEPNG_NO_COMPILE_ENCODER
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61 /*pass -DLODEPNG_NO_COMPILE_ENCODER to the compiler to disable this, or comment out LODEPNG_COMPILE_ENCODER below*/
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62 #define LODEPNG_COMPILE_ENCODER
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63 #endif
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64
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65 /*the optional built in harddisk file loading and saving functions*/
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66 #ifndef LODEPNG_NO_COMPILE_DISK
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67 /*pass -DLODEPNG_NO_COMPILE_DISK to the compiler to disable this, or comment out LODEPNG_COMPILE_DISK below*/
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68 #define LODEPNG_COMPILE_DISK
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69 #endif
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70
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71 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/
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72 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS
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73 /*pass -DLODEPNG_NO_COMPILE_ANCILLARY_CHUNKS to the compiler to disable this,
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74 or comment out LODEPNG_COMPILE_ANCILLARY_CHUNKS below*/
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75 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS
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76 #endif
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77
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78 /*ability to convert error numerical codes to English text string*/
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79 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT
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80 /*pass -DLODEPNG_NO_COMPILE_ERROR_TEXT to the compiler to disable this,
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81 or comment out LODEPNG_COMPILE_ERROR_TEXT below*/
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82 #define LODEPNG_COMPILE_ERROR_TEXT
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83 #endif
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84
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85 /*Compile the default allocators (C's free, malloc and realloc). If you disable this,
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86 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your
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87 source files with custom allocators.*/
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88 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS
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89 /*pass -DLODEPNG_NO_COMPILE_ALLOCATORS to the compiler to disable the built-in ones,
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90 or comment out LODEPNG_COMPILE_ALLOCATORS below*/
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91 #define LODEPNG_COMPILE_ALLOCATORS
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92 #endif
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93
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94 /*Disable built-in CRC function, in that case a custom implementation of
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95 lodepng_crc32 must be defined externally so that it can be linked in.
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96 The default built-in CRC code comes with 8KB of lookup tables, so for memory constrained environment you may want it
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97 disabled and provide a much smaller implementation externally as said above. You can find such an example implementation
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98 in a comment in the lodepng.c(pp) file in the 'else' case of the searchable LODEPNG_COMPILE_CRC section.*/
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99 #ifndef LODEPNG_NO_COMPILE_CRC
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100 /*pass -DLODEPNG_NO_COMPILE_CRC to the compiler to disable the built-in one,
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101 or comment out LODEPNG_COMPILE_CRC below*/
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102 #define LODEPNG_COMPILE_CRC
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103 #endif
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104
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105 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/
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106 #ifdef __cplusplus
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107 #ifndef LODEPNG_NO_COMPILE_CPP
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108 /*pass -DLODEPNG_NO_COMPILE_CPP to the compiler to disable C++ (not needed if a C-only compiler),
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109 or comment out LODEPNG_COMPILE_CPP below*/
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110 #define LODEPNG_COMPILE_CPP
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111 #endif
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112 #endif
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113
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114 #ifdef LODEPNG_COMPILE_CPP
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115 #include <vector>
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116 #include <string>
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117 #endif /*LODEPNG_COMPILE_CPP*/
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118
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119 #ifdef LODEPNG_COMPILE_PNG
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120 /*The PNG color types (also used for raw image).*/
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121 typedef enum LodePNGColorType {
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122 LCT_GREY = 0, /*grayscale: 1,2,4,8,16 bit*/
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123 LCT_RGB = 2, /*RGB: 8,16 bit*/
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124 LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/
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125 LCT_GREY_ALPHA = 4, /*grayscale with alpha: 8,16 bit*/
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126 LCT_RGBA = 6, /*RGB with alpha: 8,16 bit*/
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127 /*LCT_MAX_OCTET_VALUE lets the compiler allow this enum to represent any invalid
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128 byte value from 0 to 255 that could be present in an invalid PNG file header. Do
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129 not use, compare with or set the name LCT_MAX_OCTET_VALUE, instead either use
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130 the valid color type names above, or numeric values like 1 or 7 when checking for
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131 particular disallowed color type byte values, or cast to integer to print it.*/
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132 LCT_MAX_OCTET_VALUE = 255
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133 } LodePNGColorType;
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134
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135 #ifdef LODEPNG_COMPILE_DECODER
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136 /*
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137 Converts PNG data in memory to raw pixel data.
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138 out: Output parameter. Pointer to buffer that will contain the raw pixel data.
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139 After decoding, its size is w * h * (bytes per pixel) bytes larger than
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140 initially. Bytes per pixel depends on colortype and bitdepth.
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141 Must be freed after usage with free(*out).
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142 Note: for 16-bit per channel colors, uses big endian format like PNG does.
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143 w: Output parameter. Pointer to width of pixel data.
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144 h: Output parameter. Pointer to height of pixel data.
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145 in: Memory buffer with the PNG file.
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146 insize: size of the in buffer.
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147 colortype: the desired color type for the raw output image. See explanation on PNG color types.
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148 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types.
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149 Return value: LodePNG error code (0 means no error).
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150 */
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151 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h,
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152 const unsigned char* in, size_t insize,
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153 LodePNGColorType colortype, unsigned bitdepth);
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154
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155 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/
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156 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h,
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157 const unsigned char* in, size_t insize);
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158
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159 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/
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160 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h,
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161 const unsigned char* in, size_t insize);
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162
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163 #ifdef LODEPNG_COMPILE_DISK
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164 /*
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165 Load PNG from disk, from file with given name.
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166 Same as the other decode functions, but instead takes a filename as input.
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167
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168 NOTE: Wide-character filenames are not supported, you can use an external method
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169 to handle such files and decode in-memory.*/
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170 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h,
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171 const char* filename,
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172 LodePNGColorType colortype, unsigned bitdepth);
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173
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174 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.
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175
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176 NOTE: Wide-character filenames are not supported, you can use an external method
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177 to handle such files and decode in-memory.*/
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178 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h,
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179 const char* filename);
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180
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181 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.
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182
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183 NOTE: Wide-character filenames are not supported, you can use an external method
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184 to handle such files and decode in-memory.*/
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185 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h,
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186 const char* filename);
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187 #endif /*LODEPNG_COMPILE_DISK*/
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188 #endif /*LODEPNG_COMPILE_DECODER*/
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189
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190
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191 #ifdef LODEPNG_COMPILE_ENCODER
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192 /*
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193 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth
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194 of the output PNG image cannot be chosen, they are automatically determined
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195 by the colortype, bitdepth and content of the input pixel data.
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196 Note: for 16-bit per channel colors, needs big endian format like PNG does.
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197 out: Output parameter. Pointer to buffer that will contain the PNG image data.
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198 Must be freed after usage with free(*out).
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199 outsize: Output parameter. Pointer to the size in bytes of the out buffer.
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200 image: The raw pixel data to encode. The size of this buffer should be
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201 w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth.
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202 w: width of the raw pixel data in pixels.
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203 h: height of the raw pixel data in pixels.
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204 colortype: the color type of the raw input image. See explanation on PNG color types.
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205 bitdepth: the bit depth of the raw input image. See explanation on PNG color types.
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206 Return value: LodePNG error code (0 means no error).
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207 */
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208 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize,
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209 const unsigned char* image, unsigned w, unsigned h,
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210 LodePNGColorType colortype, unsigned bitdepth);
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211
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212 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/
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213 unsigned lodepng_encode32(unsigned char** out, size_t* outsize,
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214 const unsigned char* image, unsigned w, unsigned h);
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215
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216 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/
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217 unsigned lodepng_encode24(unsigned char** out, size_t* outsize,
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218 const unsigned char* image, unsigned w, unsigned h);
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219
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220 #ifdef LODEPNG_COMPILE_DISK
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221 /*
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222 Converts raw pixel data into a PNG file on disk.
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223 Same as the other encode functions, but instead takes a filename as output.
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224
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225 NOTE: This overwrites existing files without warning!
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226
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227 NOTE: Wide-character filenames are not supported, you can use an external method
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228 to handle such files and encode in-memory.*/
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229 unsigned lodepng_encode_file(const char* filename,
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230 const unsigned char* image, unsigned w, unsigned h,
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231 LodePNGColorType colortype, unsigned bitdepth);
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232
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233 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.
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234
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235 NOTE: Wide-character filenames are not supported, you can use an external method
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236 to handle such files and encode in-memory.*/
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237 unsigned lodepng_encode32_file(const char* filename,
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238 const unsigned char* image, unsigned w, unsigned h);
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239
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240 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.
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241
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242 NOTE: Wide-character filenames are not supported, you can use an external method
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243 to handle such files and encode in-memory.*/
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244 unsigned lodepng_encode24_file(const char* filename,
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245 const unsigned char* image, unsigned w, unsigned h);
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246 #endif /*LODEPNG_COMPILE_DISK*/
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247 #endif /*LODEPNG_COMPILE_ENCODER*/
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248
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249
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250 #ifdef LODEPNG_COMPILE_CPP
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251 namespace lodepng {
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252 #ifdef LODEPNG_COMPILE_DECODER
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253 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype
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254 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/
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255 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
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256 const unsigned char* in, size_t insize,
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257 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
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258 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
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259 const std::vector<unsigned char>& in,
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260 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
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261 #ifdef LODEPNG_COMPILE_DISK
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262 /*
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263 Converts PNG file from disk to raw pixel data in memory.
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264 Same as the other decode functions, but instead takes a filename as input.
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265
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266 NOTE: Wide-character filenames are not supported, you can use an external method
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267 to handle such files and decode in-memory.
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268 */
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269 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
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270 const std::string& filename,
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271 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
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272 #endif /* LODEPNG_COMPILE_DISK */
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273 #endif /* LODEPNG_COMPILE_DECODER */
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274
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275 #ifdef LODEPNG_COMPILE_ENCODER
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276 /*Same as lodepng_encode_memory, but encodes to an std::vector. colortype
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277 is that of the raw input data. The output PNG color type will be auto chosen.*/
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278 unsigned encode(std::vector<unsigned char>& out,
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279 const unsigned char* in, unsigned w, unsigned h,
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280 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
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281 unsigned encode(std::vector<unsigned char>& out,
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282 const std::vector<unsigned char>& in, unsigned w, unsigned h,
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283 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
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284 #ifdef LODEPNG_COMPILE_DISK
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285 /*
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286 Converts 32-bit RGBA raw pixel data into a PNG file on disk.
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287 Same as the other encode functions, but instead takes a filename as output.
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288
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289 NOTE: This overwrites existing files without warning!
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290
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291 NOTE: Wide-character filenames are not supported, you can use an external method
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292 to handle such files and decode in-memory.
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293 */
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294 unsigned encode(const std::string& filename,
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295 const unsigned char* in, unsigned w, unsigned h,
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296 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
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297 unsigned encode(const std::string& filename,
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298 const std::vector<unsigned char>& in, unsigned w, unsigned h,
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299 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
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300 #endif /* LODEPNG_COMPILE_DISK */
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301 #endif /* LODEPNG_COMPILE_ENCODER */
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302 } /* namespace lodepng */
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303 #endif /*LODEPNG_COMPILE_CPP*/
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304 #endif /*LODEPNG_COMPILE_PNG*/
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305
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306 #ifdef LODEPNG_COMPILE_ERROR_TEXT
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307 /*Returns an English description of the numerical error code.*/
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308 const char* lodepng_error_text(unsigned code);
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309 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/
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310
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311 #ifdef LODEPNG_COMPILE_DECODER
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312 /*Settings for zlib decompression*/
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313 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings;
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314 struct LodePNGDecompressSettings {
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315 /* Check LodePNGDecoderSettings for more ignorable errors such as ignore_crc */
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316 unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/
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317 unsigned ignore_nlen; /*ignore complement of len checksum in uncompressed blocks*/
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318
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319 /*Maximum decompressed size, beyond this the decoder may (and is encouraged to) stop decoding,
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320 return an error, output a data size > max_output_size and all the data up to that point. This is
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321 not hard limit nor a guarantee, but can prevent excessive memory usage. This setting is
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322 ignored by the PNG decoder, but is used by the deflate/zlib decoder and can be used by custom ones.
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323 Set to 0 to impose no limit (the default).*/
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324 size_t max_output_size;
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325
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326 /*use custom zlib decoder instead of built in one (default: null).
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327 Should return 0 if success, any non-0 if error (numeric value not exposed).*/
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328 unsigned (*custom_zlib)(unsigned char**, size_t*,
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329 const unsigned char*, size_t,
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330 const LodePNGDecompressSettings*);
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331 /*use custom deflate decoder instead of built in one (default: null)
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332 if custom_zlib is not null, custom_inflate is ignored (the zlib format uses deflate).
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333 Should return 0 if success, any non-0 if error (numeric value not exposed).*/
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334 unsigned (*custom_inflate)(unsigned char**, size_t*,
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335 const unsigned char*, size_t,
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336 const LodePNGDecompressSettings*);
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337
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338 const void* custom_context; /*optional custom settings for custom functions*/
|
|
|
339 };
|
|
|
340
|
|
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341 extern const LodePNGDecompressSettings lodepng_default_decompress_settings;
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|
|
342 void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings);
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|
|
343 #endif /*LODEPNG_COMPILE_DECODER*/
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344
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|
|
345 #ifdef LODEPNG_COMPILE_ENCODER
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346 /*
|
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|
347 Settings for zlib compression. Tweaking these settings tweaks the balance
|
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|
348 between speed and compression ratio.
|
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|
349 */
|
|
|
350 typedef struct LodePNGCompressSettings LodePNGCompressSettings;
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|
|
351 struct LodePNGCompressSettings /*deflate = compress*/ {
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|
352 /*LZ77 related settings*/
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|
353 unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/
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|
354 unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/
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355 unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/
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356 unsigned minmatch; /*minimum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/
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357 unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/
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|
|
358 unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/
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|
359
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|
360 /*use custom zlib encoder instead of built in one (default: null)*/
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361 unsigned (*custom_zlib)(unsigned char**, size_t*,
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362 const unsigned char*, size_t,
|
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|
363 const LodePNGCompressSettings*);
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|
364 /*use custom deflate encoder instead of built in one (default: null)
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|
|
365 if custom_zlib is used, custom_deflate is ignored since only the built in
|
|
|
366 zlib function will call custom_deflate*/
|
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367 unsigned (*custom_deflate)(unsigned char**, size_t*,
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|
368 const unsigned char*, size_t,
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369 const LodePNGCompressSettings*);
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370
|
|
|
371 const void* custom_context; /*optional custom settings for custom functions*/
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372 };
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373
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374 extern const LodePNGCompressSettings lodepng_default_compress_settings;
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375 void lodepng_compress_settings_init(LodePNGCompressSettings* settings);
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|
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376 #endif /*LODEPNG_COMPILE_ENCODER*/
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377
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|
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378 #ifdef LODEPNG_COMPILE_PNG
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379 /*
|
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380 Color mode of an image. Contains all information required to decode the pixel
|
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381 bits to RGBA colors. This information is the same as used in the PNG file
|
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|
382 format, and is used both for PNG and raw image data in LodePNG.
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383 */
|
|
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384 typedef struct LodePNGColorMode {
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|
385 /*header (IHDR)*/
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386 LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/
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|
|
387 unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/
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|
|
388
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|
|
389 /*
|
|
|
390 palette (PLTE and tRNS)
|
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391
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392 Dynamically allocated with the colors of the palette, including alpha.
|
|
|
393 This field may not be allocated directly, use lodepng_color_mode_init first,
|
|
|
394 then lodepng_palette_add per color to correctly initialize it (to ensure size
|
|
|
395 of exactly 1024 bytes).
|
|
|
396
|
|
|
397 The alpha channels must be set as well, set them to 255 for opaque images.
|
|
|
398
|
|
|
399 When decoding, with the default settings you can ignore this palette, since
|
|
|
400 LodePNG already fills the palette colors in the pixels of the raw RGBA output,
|
|
|
401 but when decoding to the original PNG color mode it is needed to reconstruct
|
|
|
402 the colors.
|
|
|
403
|
|
|
404 The palette is only supported for color type 3.
|
|
|
405 */
|
|
|
406 unsigned char* palette; /*palette in RGBARGBA... order. Must be either 0, or when allocated must have 1024 bytes*/
|
|
|
407 size_t palettesize; /*palette size in number of colors (amount of used bytes is 4 * palettesize)*/
|
|
|
408
|
|
|
409 /*
|
|
|
410 transparent color key (tRNS)
|
|
|
411
|
|
|
412 This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit.
|
|
|
413 For grayscale PNGs, r, g and b will all 3 be set to the same.
|
|
|
414
|
|
|
415 When decoding, by default you can ignore this information, since LodePNG sets
|
|
|
416 pixels with this key to transparent already in the raw RGBA output.
|
|
|
417
|
|
|
418 The color key is only supported for color types 0 and 2.
|
|
|
419 */
|
|
|
420 unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/
|
|
|
421 unsigned key_r; /*red/grayscale component of color key*/
|
|
|
422 unsigned key_g; /*green component of color key*/
|
|
|
423 unsigned key_b; /*blue component of color key*/
|
|
|
424 } LodePNGColorMode;
|
|
|
425
|
|
|
426 /*init, cleanup and copy functions to use with this struct*/
|
|
|
427 void lodepng_color_mode_init(LodePNGColorMode* info);
|
|
|
428 void lodepng_color_mode_cleanup(LodePNGColorMode* info);
|
|
|
429 /*return value is error code (0 means no error)*/
|
|
|
430 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source);
|
|
|
431 /* Makes a temporary LodePNGColorMode that does not need cleanup (no palette) */
|
|
|
432 LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth);
|
|
|
433
|
|
|
434 void lodepng_palette_clear(LodePNGColorMode* info);
|
|
|
435 /*add 1 color to the palette*/
|
|
|
436 unsigned lodepng_palette_add(LodePNGColorMode* info,
|
|
|
437 unsigned char r, unsigned char g, unsigned char b, unsigned char a);
|
|
|
438
|
|
|
439 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/
|
|
|
440 unsigned lodepng_get_bpp(const LodePNGColorMode* info);
|
|
|
441 /*get the amount of color channels used, based on colortype in the struct.
|
|
|
442 If a palette is used, it counts as 1 channel.*/
|
|
|
443 unsigned lodepng_get_channels(const LodePNGColorMode* info);
|
|
|
444 /*is it a grayscale type? (only colortype 0 or 4)*/
|
|
|
445 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info);
|
|
|
446 /*has it got an alpha channel? (only colortype 2 or 6)*/
|
|
|
447 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info);
|
|
|
448 /*has it got a palette? (only colortype 3)*/
|
|
|
449 unsigned lodepng_is_palette_type(const LodePNGColorMode* info);
|
|
|
450 /*only returns true if there is a palette and there is a value in the palette with alpha < 255.
|
|
|
451 Loops through the palette to check this.*/
|
|
|
452 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info);
|
|
|
453 /*
|
|
|
454 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image.
|
|
|
455 Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels).
|
|
|
456 Returns false if the image can only have opaque pixels.
|
|
|
457 In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values,
|
|
|
458 or if "key_defined" is true.
|
|
|
459 */
|
|
|
460 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info);
|
|
|
461 /*Returns the byte size of a raw image buffer with given width, height and color mode*/
|
|
|
462 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color);
|
|
|
463
|
|
|
464 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
|
465 /*The information of a Time chunk in PNG.*/
|
|
|
466 typedef struct LodePNGTime {
|
|
|
467 unsigned year; /*2 bytes used (0-65535)*/
|
|
|
468 unsigned month; /*1-12*/
|
|
|
469 unsigned day; /*1-31*/
|
|
|
470 unsigned hour; /*0-23*/
|
|
|
471 unsigned minute; /*0-59*/
|
|
|
472 unsigned second; /*0-60 (to allow for leap seconds)*/
|
|
|
473 } LodePNGTime;
|
|
|
474 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
|
|
|
475
|
|
|
476 /*Information about the PNG image, except pixels, width and height.*/
|
|
|
477 typedef struct LodePNGInfo {
|
|
|
478 /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/
|
|
|
479 unsigned compression_method;/*compression method of the original file. Always 0.*/
|
|
|
480 unsigned filter_method; /*filter method of the original file*/
|
|
|
481 unsigned interlace_method; /*interlace method of the original file: 0=none, 1=Adam7*/
|
|
|
482 LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/
|
|
|
483
|
|
|
484 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
|
485 /*
|
|
|
486 Suggested background color chunk (bKGD)
|
|
|
487
|
|
|
488 This uses the same color mode and bit depth as the PNG (except no alpha channel),
|
|
|
489 with values truncated to the bit depth in the unsigned integer.
|
|
|
490
|
|
|
491 For grayscale and palette PNGs, the value is stored in background_r. The values
|
|
|
492 in background_g and background_b are then unused. The decoder will set them
|
|
|
493 equal to background_r, the encoder ignores them in this case.
|
|
|
494
|
|
|
495 When decoding, you may get these in a different color mode than the one you requested
|
|
|
496 for the raw pixels: the colortype and bitdepth defined by info_png.color, that is the
|
|
|
497 ones defined in the header of the PNG image, are used.
|
|
|
498
|
|
|
499 When encoding with auto_convert, you must use the color model defined in info_png.color for
|
|
|
500 these values. The encoder normally ignores info_png.color when auto_convert is on, but will
|
|
|
501 use it to interpret these values (and convert copies of them to its chosen color model).
|
|
|
502
|
|
|
503 When encoding, avoid setting this to an expensive color, such as a non-gray value
|
|
|
504 when the image is gray, or the compression will be worse since it will be forced to
|
|
|
505 write the PNG with a more expensive color mode (when auto_convert is on).
|
|
|
506
|
|
|
507 The decoder does not use this background color to edit the color of pixels. This is a
|
|
|
508 completely optional metadata feature.
|
|
|
509 */
|
|
|
510 unsigned background_defined; /*is a suggested background color given?*/
|
|
|
511 unsigned background_r; /*red/gray/palette component of suggested background color*/
|
|
|
512 unsigned background_g; /*green component of suggested background color*/
|
|
|
513 unsigned background_b; /*blue component of suggested background color*/
|
|
|
514
|
|
|
515 /*
|
|
|
516 Non-international text chunks (tEXt and zTXt)
|
|
|
517
|
|
|
518 The char** arrays each contain num strings. The actual messages are in
|
|
|
519 text_strings, while text_keys are keywords that give a short description what
|
|
|
520 the actual text represents, e.g. Title, Author, Description, or anything else.
|
|
|
521
|
|
|
522 All the string fields below including strings, keys, names and language tags are null terminated.
|
|
|
523 The PNG specification uses null characters for the keys, names and tags, and forbids null
|
|
|
524 characters to appear in the main text which is why we can use null termination everywhere here.
|
|
|
525
|
|
|
526 A keyword is minimum 1 character and maximum 79 characters long (plus the
|
|
|
527 additional null terminator). It's discouraged to use a single line length
|
|
|
528 longer than 79 characters for texts.
|
|
|
529
|
|
|
530 Don't allocate these text buffers yourself. Use the init/cleanup functions
|
|
|
531 correctly and use lodepng_add_text and lodepng_clear_text.
|
|
|
532
|
|
|
533 Standard text chunk keywords and strings are encoded using Latin-1.
|
|
|
534 */
|
|
|
535 size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/
|
|
|
536 char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/
|
|
|
537 char** text_strings; /*the actual text*/
|
|
|
538
|
|
|
539 /*
|
|
|
540 International text chunks (iTXt)
|
|
|
541 Similar to the non-international text chunks, but with additional strings
|
|
|
542 "langtags" and "transkeys", and the following text encodings are used:
|
|
|
543 keys: Latin-1, langtags: ASCII, transkeys and strings: UTF-8.
|
|
|
544 keys must be 1-79 characters (plus the additional null terminator), the other
|
|
|
545 strings are any length.
|
|
|
546 */
|
|
|
547 size_t itext_num; /*the amount of international texts in this PNG*/
|
|
|
548 char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/
|
|
|
549 char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/
|
|
|
550 char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/
|
|
|
551 char** itext_strings; /*the actual international text - UTF-8 string*/
|
|
|
552
|
|
|
553 /*time chunk (tIME)*/
|
|
|
554 unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/
|
|
|
555 LodePNGTime time;
|
|
|
556
|
|
|
557 /*phys chunk (pHYs)*/
|
|
|
558 unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/
|
|
|
559 unsigned phys_x; /*pixels per unit in x direction*/
|
|
|
560 unsigned phys_y; /*pixels per unit in y direction*/
|
|
|
561 unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/
|
|
|
562
|
|
|
563 /*
|
|
|
564 Color profile related chunks: gAMA, cHRM, sRGB, iCPP, sBIT
|
|
|
565
|
|
|
566 LodePNG does not apply any color conversions on pixels in the encoder or decoder and does not interpret these color
|
|
|
567 profile values. It merely passes on the information. If you wish to use color profiles and convert colors, please
|
|
|
568 use these values with a color management library.
|
|
|
569
|
|
|
570 See the PNG, ICC and sRGB specifications for more information about the meaning of these values.
|
|
|
571 */
|
|
|
572
|
|
|
573 /* gAMA chunk: optional, overridden by sRGB or iCCP if those are present. */
|
|
|
574 unsigned gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */
|
|
|
575 unsigned gama_gamma; /* Gamma exponent times 100000 */
|
|
|
576
|
|
|
577 /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */
|
|
|
578 unsigned chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */
|
|
|
579 unsigned chrm_white_x; /* White Point x times 100000 */
|
|
|
580 unsigned chrm_white_y; /* White Point y times 100000 */
|
|
|
581 unsigned chrm_red_x; /* Red x times 100000 */
|
|
|
582 unsigned chrm_red_y; /* Red y times 100000 */
|
|
|
583 unsigned chrm_green_x; /* Green x times 100000 */
|
|
|
584 unsigned chrm_green_y; /* Green y times 100000 */
|
|
|
585 unsigned chrm_blue_x; /* Blue x times 100000 */
|
|
|
586 unsigned chrm_blue_y; /* Blue y times 100000 */
|
|
|
587
|
|
|
588 /*
|
|
|
589 sRGB chunk: optional. May not appear at the same time as iCCP.
|
|
|
590 If gAMA is also present gAMA must contain value 45455.
|
|
|
591 If cHRM is also present cHRM must contain respectively 31270,32900,64000,33000,30000,60000,15000,6000.
|
|
|
592 */
|
|
|
593 unsigned srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */
|
|
|
594 unsigned srgb_intent; /* Rendering intent: 0=perceptual, 1=rel. colorimetric, 2=saturation, 3=abs. colorimetric */
|
|
|
595
|
|
|
596 /*
|
|
|
597 iCCP chunk: optional. May not appear at the same time as sRGB.
|
|
|
598
|
|
|
599 LodePNG does not parse or use the ICC profile (except its color space header field for an edge case), a
|
|
|
600 separate library to handle the ICC data (not included in LodePNG) format is needed to use it for color
|
|
|
601 management and conversions.
|
|
|
602
|
|
|
603 For encoding, if iCCP is present, gAMA and cHRM are recommended to be added as well with values that match the ICC
|
|
|
604 profile as closely as possible, if you wish to do this you should provide the correct values for gAMA and cHRM and
|
|
|
605 enable their '_defined' flags since LodePNG will not automatically compute them from the ICC profile.
|
|
|
606
|
|
|
607 For encoding, the ICC profile is required by the PNG specification to be an "RGB" profile for non-gray
|
|
|
608 PNG color types and a "GRAY" profile for gray PNG color types. If you disable auto_convert, you must ensure
|
|
|
609 the ICC profile type matches your requested color type, else the encoder gives an error. If auto_convert is
|
|
|
610 enabled (the default), and the ICC profile is not a good match for the pixel data, this will result in an encoder
|
|
|
611 error if the pixel data has non-gray pixels for a GRAY profile, or a silent less-optimal compression of the pixel
|
|
|
612 data if the pixels could be encoded as grayscale but the ICC profile is RGB.
|
|
|
613
|
|
|
614 To avoid this do not set an ICC profile in the image unless there is a good reason for it, and when doing so
|
|
|
615 make sure you compute it carefully to avoid the above problems.
|
|
|
616 */
|
|
|
617 unsigned iccp_defined; /* Whether an iCCP chunk is present (0 = not present, 1 = present). */
|
|
|
618 char* iccp_name; /* Null terminated string with profile name, 1-79 bytes */
|
|
|
619 /*
|
|
|
620 The ICC profile in iccp_profile_size bytes.
|
|
|
621 Don't allocate this buffer yourself. Use the init/cleanup functions
|
|
|
622 correctly and use lodepng_set_icc and lodepng_clear_icc.
|
|
|
623 */
|
|
|
624 unsigned char* iccp_profile;
|
|
|
625 unsigned iccp_profile_size; /* The size of iccp_profile in bytes */
|
|
|
626
|
|
|
627 /*
|
|
|
628 sBIT chunk: significant bits. Optional metadata, only set this if needed.
|
|
|
629
|
|
|
630 If defined, these values give the bit depth of the original data. Since PNG only stores 1, 2, 4, 8 or 16-bit
|
|
|
631 per channel data, the significant bits value can be used to indicate the original encoded data has another
|
|
|
632 sample depth, such as 10 or 12.
|
|
|
633
|
|
|
634 Encoders using this value, when storing the pixel data, should use the most significant bits
|
|
|
635 of the data to store the original bits, and use a good sample depth scaling method such as
|
|
|
636 "left bit replication" to fill in the least significant bits, rather than fill zeroes.
|
|
|
637
|
|
|
638 Decoders using this value, if able to work with data that's e.g. 10-bit or 12-bit, should right
|
|
|
639 shift the data to go back to the original bit depth, but decoders are also allowed to ignore
|
|
|
640 sbit and work e.g. with the 8-bit or 16-bit data from the PNG directly, since thanks
|
|
|
641 to the encoder contract, the values encoded in PNG are in valid range for the PNG bit depth.
|
|
|
642
|
|
|
643 For grayscale images, sbit_g and sbit_b are not used, and for images that don't use color
|
|
|
644 type RGBA or grayscale+alpha, sbit_a is not used (it's not used even for palette images with
|
|
|
645 translucent palette values, or images with color key). The values that are used must be
|
|
|
646 greater than zero and smaller than or equal to the PNG bit depth.
|
|
|
647
|
|
|
648 The color type from the header in the PNG image defines these used and unused fields: if
|
|
|
649 decoding with a color mode conversion, such as always decoding to RGBA, this metadata still
|
|
|
650 only uses the color type of the original PNG, and may e.g. lack the alpha channel info
|
|
|
651 if the PNG was RGB. When encoding with auto_convert (as well as without), also always the
|
|
|
652 color model defined in info_png.color determines this.
|
|
|
653
|
|
|
654 NOTE: enabling sbit can hurt compression, because the encoder can then not always use
|
|
|
655 auto_convert to choose a more optimal color mode for the data, because the PNG format has
|
|
|
656 strict requirements for the allowed sbit values in combination with color modes.
|
|
|
657 For example, setting these fields to 10-bit will force the encoder to keep using a 16-bit per channel
|
|
|
658 color mode, even if the pixel data would in fact fit in a more efficient 8-bit mode.
|
|
|
659 */
|
|
|
660 unsigned sbit_defined; /*is significant bits given? if not, the values below are unused*/
|
|
|
661 unsigned sbit_r; /*red or gray component of significant bits*/
|
|
|
662 unsigned sbit_g; /*green component of significant bits*/
|
|
|
663 unsigned sbit_b; /*blue component of significant bits*/
|
|
|
664 unsigned sbit_a; /*alpha component of significant bits*/
|
|
|
665
|
|
|
666 /* End of color profile related chunks */
|
|
|
667
|
|
|
668
|
|
|
669 /*
|
|
|
670 unknown chunks: chunks not known by LodePNG, passed on byte for byte.
|
|
|
671
|
|
|
672 There are 3 buffers, one for each position in the PNG where unknown chunks can appear.
|
|
|
673 Each buffer contains all unknown chunks for that position consecutively.
|
|
|
674 The 3 positions are:
|
|
|
675 0: between IHDR and PLTE, 1: between PLTE and IDAT, 2: between IDAT and IEND.
|
|
|
676
|
|
|
677 For encoding, do not store critical chunks or known chunks that are enabled with a "_defined" flag
|
|
|
678 above in here, since the encoder will blindly follow this and could then encode an invalid PNG file
|
|
|
679 (such as one with two IHDR chunks or the disallowed combination of sRGB with iCCP). But do use
|
|
|
680 this if you wish to store an ancillary chunk that is not supported by LodePNG (such as sPLT or hIST),
|
|
|
681 or any non-standard PNG chunk.
|
|
|
682
|
|
|
683 Do not allocate or traverse this data yourself. Use the chunk traversing functions declared
|
|
|
684 later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct.
|
|
|
685 */
|
|
|
686 unsigned char* unknown_chunks_data[3];
|
|
|
687 size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/
|
|
|
688 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
|
|
|
689 } LodePNGInfo;
|
|
|
690
|
|
|
691 /*init, cleanup and copy functions to use with this struct*/
|
|
|
692 void lodepng_info_init(LodePNGInfo* info);
|
|
|
693 void lodepng_info_cleanup(LodePNGInfo* info);
|
|
|
694 /*return value is error code (0 means no error)*/
|
|
|
695 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source);
|
|
|
696
|
|
|
697 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
|
698 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/
|
|
|
699 void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
|
|
|
700
|
|
|
701 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
|
|
|
702 const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/
|
|
|
703 void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/
|
|
|
704
|
|
|
705 /*replaces if exists*/
|
|
|
706 unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size);
|
|
|
707 void lodepng_clear_icc(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
|
|
|
708 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
|
|
|
709
|
|
|
710 /*
|
|
|
711 Converts raw buffer from one color type to another color type, based on
|
|
|
712 LodePNGColorMode structs to describe the input and output color type.
|
|
|
713 See the reference manual at the end of this header file to see which color conversions are supported.
|
|
|
714 return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported)
|
|
|
715 The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel
|
|
|
716 of the output color type (lodepng_get_bpp).
|
|
|
717 For < 8 bpp images, there should not be padding bits at the end of scanlines.
|
|
|
718 For 16-bit per channel colors, uses big endian format like PNG does.
|
|
|
719 Return value is LodePNG error code
|
|
|
720 */
|
|
|
721 unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
|
|
|
722 const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in,
|
|
|
723 unsigned w, unsigned h);
|
|
|
724
|
|
|
725 #ifdef LODEPNG_COMPILE_DECODER
|
|
|
726 /*
|
|
|
727 Settings for the decoder. This contains settings for the PNG and the Zlib
|
|
|
728 decoder, but not the Info settings from the Info structs.
|
|
|
729 */
|
|
|
730 typedef struct LodePNGDecoderSettings {
|
|
|
731 LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/
|
|
|
732
|
|
|
733 /* Check LodePNGDecompressSettings for more ignorable errors such as ignore_adler32 */
|
|
|
734 unsigned ignore_crc; /*ignore CRC checksums*/
|
|
|
735 unsigned ignore_critical; /*ignore unknown critical chunks*/
|
|
|
736 unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/
|
|
|
737 /* TODO: make a system involving warnings with levels and a strict mode instead. Other potentially recoverable
|
|
|
738 errors: srgb rendering intent value, size of content of ancillary chunks, more than 79 characters for some
|
|
|
739 strings, placement/combination rules for ancillary chunks, crc of unknown chunks, allowed characters
|
|
|
740 in string keys, etc... */
|
|
|
741
|
|
|
742 unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/
|
|
|
743
|
|
|
744 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
|
745 unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/
|
|
|
746
|
|
|
747 /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/
|
|
|
748 unsigned remember_unknown_chunks;
|
|
|
749
|
|
|
750 /* maximum size for decompressed text chunks. If a text chunk's text is larger than this, an error is returned,
|
|
|
751 unless reading text chunks is disabled or this limit is set higher or disabled. Set to 0 to allow any size.
|
|
|
752 By default it is a value that prevents unreasonably large strings from hogging memory. */
|
|
|
753 size_t max_text_size;
|
|
|
754
|
|
|
755 /* maximum size for compressed ICC chunks. If the ICC profile is larger than this, an error will be returned. Set to
|
|
|
756 0 to allow any size. By default this is a value that prevents ICC profiles that would be much larger than any
|
|
|
757 legitimate profile could be to hog memory. */
|
|
|
758 size_t max_icc_size;
|
|
|
759 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
|
|
|
760 } LodePNGDecoderSettings;
|
|
|
761
|
|
|
762 void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings);
|
|
|
763 #endif /*LODEPNG_COMPILE_DECODER*/
|
|
|
764
|
|
|
765 #ifdef LODEPNG_COMPILE_ENCODER
|
|
|
766 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/
|
|
|
767 typedef enum LodePNGFilterStrategy {
|
|
|
768 /*every filter at zero*/
|
|
|
769 LFS_ZERO = 0,
|
|
|
770 /*every filter at 1, 2, 3 or 4 (paeth), unlike LFS_ZERO not a good choice, but for testing*/
|
|
|
771 LFS_ONE = 1,
|
|
|
772 LFS_TWO = 2,
|
|
|
773 LFS_THREE = 3,
|
|
|
774 LFS_FOUR = 4,
|
|
|
775 /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/
|
|
|
776 LFS_MINSUM,
|
|
|
777 /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending
|
|
|
778 on the image, this is better or worse than minsum.*/
|
|
|
779 LFS_ENTROPY,
|
|
|
780 /*
|
|
|
781 Brute-force-search PNG filters by compressing each filter for each scanline.
|
|
|
782 Experimental, very slow, and only rarely gives better compression than MINSUM.
|
|
|
783 */
|
|
|
784 LFS_BRUTE_FORCE,
|
|
|
785 /*use predefined_filters buffer: you specify the filter type for each scanline*/
|
|
|
786 LFS_PREDEFINED
|
|
|
787 } LodePNGFilterStrategy;
|
|
|
788
|
|
|
789 /*Gives characteristics about the integer RGBA colors of the image (count, alpha channel usage, bit depth, ...),
|
|
|
790 which helps decide which color model to use for encoding.
|
|
|
791 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/
|
|
|
792 typedef struct LodePNGColorStats {
|
|
|
793 unsigned colored; /*not grayscale*/
|
|
|
794 unsigned key; /*image is not opaque and color key is possible instead of full alpha*/
|
|
|
795 unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/
|
|
|
796 unsigned short key_g;
|
|
|
797 unsigned short key_b;
|
|
|
798 unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/
|
|
|
799 unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16 or allow_palette is disabled.*/
|
|
|
800 unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order, only valid when numcolors is valid*/
|
|
|
801 unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for grayscale only. 16 if 16-bit per channel required.*/
|
|
|
802 size_t numpixels;
|
|
|
803
|
|
|
804 /*user settings for computing/using the stats*/
|
|
|
805 unsigned allow_palette; /*default 1. if 0, disallow choosing palette colortype in auto_choose_color, and don't count numcolors*/
|
|
|
806 unsigned allow_greyscale; /*default 1. if 0, choose RGB or RGBA even if the image only has gray colors*/
|
|
|
807 } LodePNGColorStats;
|
|
|
808
|
|
|
809 void lodepng_color_stats_init(LodePNGColorStats* stats);
|
|
|
810
|
|
|
811 /*Get a LodePNGColorStats of the image. The stats must already have been inited.
|
|
|
812 Returns error code (e.g. alloc fail) or 0 if ok.*/
|
|
|
813 unsigned lodepng_compute_color_stats(LodePNGColorStats* stats,
|
|
|
814 const unsigned char* image, unsigned w, unsigned h,
|
|
|
815 const LodePNGColorMode* mode_in);
|
|
|
816
|
|
|
817 /*Settings for the encoder.*/
|
|
|
818 typedef struct LodePNGEncoderSettings {
|
|
|
819 LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/
|
|
|
820
|
|
|
821 unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/
|
|
|
822
|
|
|
823 /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than
|
|
|
824 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to
|
|
|
825 completely follow the official PNG heuristic, filter_palette_zero must be true and
|
|
|
826 filter_strategy must be LFS_MINSUM*/
|
|
|
827 unsigned filter_palette_zero;
|
|
|
828 /*Which filter strategy to use when not using zeroes due to filter_palette_zero.
|
|
|
829 Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/
|
|
|
830 LodePNGFilterStrategy filter_strategy;
|
|
|
831 /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with
|
|
|
832 the same length as the amount of scanlines in the image, and each value must <= 5. You
|
|
|
833 have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero
|
|
|
834 must be set to 0 to ensure this is also used on palette or low bitdepth images.*/
|
|
|
835 const unsigned char* predefined_filters;
|
|
|
836
|
|
|
837 /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette).
|
|
|
838 If colortype is 3, PLTE is always created. If color type is explicitely set
|
|
|
839 to a grayscale type (1 or 4), this is not done and is ignored. If enabling this,
|
|
|
840 a palette must be present in the info_png.
|
|
|
841 NOTE: enabling this may worsen compression if auto_convert is used to choose
|
|
|
842 optimal color mode, because it cannot use grayscale color modes in this case*/
|
|
|
843 unsigned force_palette;
|
|
|
844 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
|
845 /*add LodePNG identifier and version as a text chunk, for debugging*/
|
|
|
846 unsigned add_id;
|
|
|
847 /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/
|
|
|
848 unsigned text_compression;
|
|
|
849 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
|
|
|
850 } LodePNGEncoderSettings;
|
|
|
851
|
|
|
852 void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings);
|
|
|
853 #endif /*LODEPNG_COMPILE_ENCODER*/
|
|
|
854
|
|
|
855
|
|
|
856 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER)
|
|
|
857 /*The settings, state and information for extended encoding and decoding.*/
|
|
|
858 typedef struct LodePNGState {
|
|
|
859 #ifdef LODEPNG_COMPILE_DECODER
|
|
|
860 LodePNGDecoderSettings decoder; /*the decoding settings*/
|
|
|
861 #endif /*LODEPNG_COMPILE_DECODER*/
|
|
|
862 #ifdef LODEPNG_COMPILE_ENCODER
|
|
|
863 LodePNGEncoderSettings encoder; /*the encoding settings*/
|
|
|
864 #endif /*LODEPNG_COMPILE_ENCODER*/
|
|
|
865 LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/
|
|
|
866 LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/
|
|
|
867 unsigned error;
|
|
|
868 } LodePNGState;
|
|
|
869
|
|
|
870 /*init, cleanup and copy functions to use with this struct*/
|
|
|
871 void lodepng_state_init(LodePNGState* state);
|
|
|
872 void lodepng_state_cleanup(LodePNGState* state);
|
|
|
873 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source);
|
|
|
874 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */
|
|
|
875
|
|
|
876 #ifdef LODEPNG_COMPILE_DECODER
|
|
|
877 /*
|
|
|
878 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and
|
|
|
879 getting much more information about the PNG image and color mode.
|
|
|
880 */
|
|
|
881 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
|
|
|
882 LodePNGState* state,
|
|
|
883 const unsigned char* in, size_t insize);
|
|
|
884
|
|
|
885 /*
|
|
|
886 Read the PNG header, but not the actual data. This returns only the information
|
|
|
887 that is in the IHDR chunk of the PNG, such as width, height and color type. The
|
|
|
888 information is placed in the info_png field of the LodePNGState.
|
|
|
889 */
|
|
|
890 unsigned lodepng_inspect(unsigned* w, unsigned* h,
|
|
|
891 LodePNGState* state,
|
|
|
892 const unsigned char* in, size_t insize);
|
|
|
893 #endif /*LODEPNG_COMPILE_DECODER*/
|
|
|
894
|
|
|
895 /*
|
|
|
896 Reads one metadata chunk (other than IHDR, which is handled by lodepng_inspect)
|
|
|
897 of the PNG file and outputs what it read in the state. Returns error code on failure.
|
|
|
898 Use lodepng_inspect first with a new state, then e.g. lodepng_chunk_find_const
|
|
|
899 to find the desired chunk type, and if non null use lodepng_inspect_chunk (with
|
|
|
900 chunk_pointer - start_of_file as pos).
|
|
|
901 Supports most metadata chunks from the PNG standard (gAMA, bKGD, tEXt, ...).
|
|
|
902 Ignores unsupported, unknown, non-metadata or IHDR chunks (without error).
|
|
|
903 Requirements: &in[pos] must point to start of a chunk, must use regular
|
|
|
904 lodepng_inspect first since format of most other chunks depends on IHDR, and if
|
|
|
905 there is a PLTE chunk, that one must be inspected before tRNS or bKGD.
|
|
|
906 */
|
|
|
907 unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos,
|
|
|
908 const unsigned char* in, size_t insize);
|
|
|
909
|
|
|
910 #ifdef LODEPNG_COMPILE_ENCODER
|
|
|
911 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/
|
|
|
912 unsigned lodepng_encode(unsigned char** out, size_t* outsize,
|
|
|
913 const unsigned char* image, unsigned w, unsigned h,
|
|
|
914 LodePNGState* state);
|
|
|
915 #endif /*LODEPNG_COMPILE_ENCODER*/
|
|
|
916
|
|
|
917 /*
|
|
|
918 The lodepng_chunk functions are normally not needed, except to traverse the
|
|
|
919 unknown chunks stored in the LodePNGInfo struct, or add new ones to it.
|
|
|
920 It also allows traversing the chunks of an encoded PNG file yourself.
|
|
|
921
|
|
|
922 The chunk pointer always points to the beginning of the chunk itself, that is
|
|
|
923 the first byte of the 4 length bytes.
|
|
|
924
|
|
|
925 In the PNG file format, chunks have the following format:
|
|
|
926 -4 bytes length: length of the data of the chunk in bytes (chunk itself is 12 bytes longer)
|
|
|
927 -4 bytes chunk type (ASCII a-z,A-Z only, see below)
|
|
|
928 -length bytes of data (may be 0 bytes if length was 0)
|
|
|
929 -4 bytes of CRC, computed on chunk name + data
|
|
|
930
|
|
|
931 The first chunk starts at the 8th byte of the PNG file, the entire rest of the file
|
|
|
932 exists out of concatenated chunks with the above format.
|
|
|
933
|
|
|
934 PNG standard chunk ASCII naming conventions:
|
|
|
935 -First byte: uppercase = critical, lowercase = ancillary
|
|
|
936 -Second byte: uppercase = public, lowercase = private
|
|
|
937 -Third byte: must be uppercase
|
|
|
938 -Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy
|
|
|
939 */
|
|
|
940
|
|
|
941 /*
|
|
|
942 Gets the length of the data of the chunk. Total chunk length has 12 bytes more.
|
|
|
943 There must be at least 4 bytes to read from. If the result value is too large,
|
|
|
944 it may be corrupt data.
|
|
|
945 */
|
|
|
946 unsigned lodepng_chunk_length(const unsigned char* chunk);
|
|
|
947
|
|
|
948 /*puts the 4-byte type in null terminated string*/
|
|
|
949 void lodepng_chunk_type(char type[5], const unsigned char* chunk);
|
|
|
950
|
|
|
951 /*check if the type is the given type*/
|
|
|
952 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type);
|
|
|
953
|
|
|
954 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/
|
|
|
955 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk);
|
|
|
956
|
|
|
957 /*0: public, 1: private (see PNG standard)*/
|
|
|
958 unsigned char lodepng_chunk_private(const unsigned char* chunk);
|
|
|
959
|
|
|
960 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/
|
|
|
961 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk);
|
|
|
962
|
|
|
963 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/
|
|
|
964 unsigned char* lodepng_chunk_data(unsigned char* chunk);
|
|
|
965 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk);
|
|
|
966
|
|
|
967 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/
|
|
|
968 unsigned lodepng_chunk_check_crc(const unsigned char* chunk);
|
|
|
969
|
|
|
970 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/
|
|
|
971 void lodepng_chunk_generate_crc(unsigned char* chunk);
|
|
|
972
|
|
|
973 /*
|
|
|
974 Iterate to next chunks, allows iterating through all chunks of the PNG file.
|
|
|
975 Input must be at the beginning of a chunk (result of a previous lodepng_chunk_next call,
|
|
|
976 or the 8th byte of a PNG file which always has the first chunk), or alternatively may
|
|
|
977 point to the first byte of the PNG file (which is not a chunk but the magic header, the
|
|
|
978 function will then skip over it and return the first real chunk).
|
|
|
979 Will output pointer to the start of the next chunk, or at or beyond end of the file if there
|
|
|
980 is no more chunk after this or possibly if the chunk is corrupt.
|
|
|
981 Start this process at the 8th byte of the PNG file.
|
|
|
982 In a non-corrupt PNG file, the last chunk should have name "IEND".
|
|
|
983 */
|
|
|
984 unsigned char* lodepng_chunk_next(unsigned char* chunk, unsigned char* end);
|
|
|
985 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk, const unsigned char* end);
|
|
|
986
|
|
|
987 /*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/
|
|
|
988 unsigned char* lodepng_chunk_find(unsigned char* chunk, unsigned char* end, const char type[5]);
|
|
|
989 const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]);
|
|
|
990
|
|
|
991 /*
|
|
|
992 Appends chunk to the data in out. The given chunk should already have its chunk header.
|
|
|
993 The out variable and outsize are updated to reflect the new reallocated buffer.
|
|
|
994 Returns error code (0 if it went ok)
|
|
|
995 */
|
|
|
996 unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk);
|
|
|
997
|
|
|
998 /*
|
|
|
999 Appends new chunk to out. The chunk to append is given by giving its length, type
|
|
|
1000 and data separately. The type is a 4-letter string.
|
|
|
1001 The out variable and outsize are updated to reflect the new reallocated buffer.
|
|
|
1002 Returne error code (0 if it went ok)
|
|
|
1003 */
|
|
|
1004 unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length,
|
|
|
1005 const char* type, const unsigned char* data);
|
|
|
1006
|
|
|
1007
|
|
|
1008 /*Calculate CRC32 of buffer*/
|
|
|
1009 unsigned lodepng_crc32(const unsigned char* buf, size_t len);
|
|
|
1010 #endif /*LODEPNG_COMPILE_PNG*/
|
|
|
1011
|
|
|
1012
|
|
|
1013 #ifdef LODEPNG_COMPILE_ZLIB
|
|
|
1014 /*
|
|
|
1015 This zlib part can be used independently to zlib compress and decompress a
|
|
|
1016 buffer. It cannot be used to create gzip files however, and it only supports the
|
|
|
1017 part of zlib that is required for PNG, it does not support dictionaries.
|
|
|
1018 */
|
|
|
1019
|
|
|
1020 #ifdef LODEPNG_COMPILE_DECODER
|
|
|
1021 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/
|
|
|
1022 unsigned lodepng_inflate(unsigned char** out, size_t* outsize,
|
|
|
1023 const unsigned char* in, size_t insize,
|
|
|
1024 const LodePNGDecompressSettings* settings);
|
|
|
1025
|
|
|
1026 /*
|
|
|
1027 Decompresses Zlib data. Reallocates the out buffer and appends the data. The
|
|
|
1028 data must be according to the zlib specification.
|
|
|
1029 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid
|
|
|
1030 buffer and *outsize its size in bytes. out must be freed by user after usage.
|
|
|
1031 */
|
|
|
1032 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize,
|
|
|
1033 const unsigned char* in, size_t insize,
|
|
|
1034 const LodePNGDecompressSettings* settings);
|
|
|
1035 #endif /*LODEPNG_COMPILE_DECODER*/
|
|
|
1036
|
|
|
1037 #ifdef LODEPNG_COMPILE_ENCODER
|
|
|
1038 /*
|
|
|
1039 Compresses data with Zlib. Reallocates the out buffer and appends the data.
|
|
|
1040 Zlib adds a small header and trailer around the deflate data.
|
|
|
1041 The data is output in the format of the zlib specification.
|
|
|
1042 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid
|
|
|
1043 buffer and *outsize its size in bytes. out must be freed by user after usage.
|
|
|
1044 */
|
|
|
1045 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize,
|
|
|
1046 const unsigned char* in, size_t insize,
|
|
|
1047 const LodePNGCompressSettings* settings);
|
|
|
1048
|
|
|
1049 /*
|
|
|
1050 Find length-limited Huffman code for given frequencies. This function is in the
|
|
|
1051 public interface only for tests, it's used internally by lodepng_deflate.
|
|
|
1052 */
|
|
|
1053 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies,
|
|
|
1054 size_t numcodes, unsigned maxbitlen);
|
|
|
1055
|
|
|
1056 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/
|
|
|
1057 unsigned lodepng_deflate(unsigned char** out, size_t* outsize,
|
|
|
1058 const unsigned char* in, size_t insize,
|
|
|
1059 const LodePNGCompressSettings* settings);
|
|
|
1060
|
|
|
1061 #endif /*LODEPNG_COMPILE_ENCODER*/
|
|
|
1062 #endif /*LODEPNG_COMPILE_ZLIB*/
|
|
|
1063
|
|
|
1064 #ifdef LODEPNG_COMPILE_DISK
|
|
|
1065 /*
|
|
|
1066 Load a file from disk into buffer. The function allocates the out buffer, and
|
|
|
1067 after usage you should free it.
|
|
|
1068 out: output parameter, contains pointer to loaded buffer.
|
|
|
1069 outsize: output parameter, size of the allocated out buffer
|
|
|
1070 filename: the path to the file to load
|
|
|
1071 return value: error code (0 means ok)
|
|
|
1072
|
|
|
1073 NOTE: Wide-character filenames are not supported, you can use an external method
|
|
|
1074 to handle such files and decode in-memory.
|
|
|
1075 */
|
|
|
1076 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename);
|
|
|
1077
|
|
|
1078 /*
|
|
|
1079 Save a file from buffer to disk. Warning, if it exists, this function overwrites
|
|
|
1080 the file without warning!
|
|
|
1081 buffer: the buffer to write
|
|
|
1082 buffersize: size of the buffer to write
|
|
|
1083 filename: the path to the file to save to
|
|
|
1084 return value: error code (0 means ok)
|
|
|
1085
|
|
|
1086 NOTE: Wide-character filenames are not supported, you can use an external method
|
|
|
1087 to handle such files and encode in-memory
|
|
|
1088 */
|
|
|
1089 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename);
|
|
|
1090 #endif /*LODEPNG_COMPILE_DISK*/
|
|
|
1091
|
|
|
1092 #ifdef LODEPNG_COMPILE_CPP
|
|
|
1093 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */
|
|
|
1094 namespace lodepng {
|
|
|
1095 #ifdef LODEPNG_COMPILE_PNG
|
|
|
1096 class State : public LodePNGState {
|
|
|
1097 public:
|
|
|
1098 State();
|
|
|
1099 State(const State& other);
|
|
|
1100 ~State();
|
|
|
1101 State& operator=(const State& other);
|
|
|
1102 };
|
|
|
1103
|
|
|
1104 #ifdef LODEPNG_COMPILE_DECODER
|
|
|
1105 /* Same as other lodepng::decode, but using a State for more settings and information. */
|
|
|
1106 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
|
|
|
1107 State& state,
|
|
|
1108 const unsigned char* in, size_t insize);
|
|
|
1109 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
|
|
|
1110 State& state,
|
|
|
1111 const std::vector<unsigned char>& in);
|
|
|
1112 #endif /*LODEPNG_COMPILE_DECODER*/
|
|
|
1113
|
|
|
1114 #ifdef LODEPNG_COMPILE_ENCODER
|
|
|
1115 /* Same as other lodepng::encode, but using a State for more settings and information. */
|
|
|
1116 unsigned encode(std::vector<unsigned char>& out,
|
|
|
1117 const unsigned char* in, unsigned w, unsigned h,
|
|
|
1118 State& state);
|
|
|
1119 unsigned encode(std::vector<unsigned char>& out,
|
|
|
1120 const std::vector<unsigned char>& in, unsigned w, unsigned h,
|
|
|
1121 State& state);
|
|
|
1122 #endif /*LODEPNG_COMPILE_ENCODER*/
|
|
|
1123
|
|
|
1124 #ifdef LODEPNG_COMPILE_DISK
|
|
|
1125 /*
|
|
|
1126 Load a file from disk into an std::vector.
|
|
|
1127 return value: error code (0 means ok)
|
|
|
1128
|
|
|
1129 NOTE: Wide-character filenames are not supported, you can use an external method
|
|
|
1130 to handle such files and decode in-memory
|
|
|
1131 */
|
|
|
1132 unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename);
|
|
|
1133
|
|
|
1134 /*
|
|
|
1135 Save the binary data in an std::vector to a file on disk. The file is overwritten
|
|
|
1136 without warning.
|
|
|
1137
|
|
|
1138 NOTE: Wide-character filenames are not supported, you can use an external method
|
|
|
1139 to handle such files and encode in-memory
|
|
|
1140 */
|
|
|
1141 unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename);
|
|
|
1142 #endif /* LODEPNG_COMPILE_DISK */
|
|
|
1143 #endif /* LODEPNG_COMPILE_PNG */
|
|
|
1144
|
|
|
1145 #ifdef LODEPNG_COMPILE_ZLIB
|
|
|
1146 #ifdef LODEPNG_COMPILE_DECODER
|
|
|
1147 /* Zlib-decompress an unsigned char buffer */
|
|
|
1148 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
|
|
|
1149 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings);
|
|
|
1150
|
|
|
1151 /* Zlib-decompress an std::vector */
|
|
|
1152 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
|
|
|
1153 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings);
|
|
|
1154 #endif /* LODEPNG_COMPILE_DECODER */
|
|
|
1155
|
|
|
1156 #ifdef LODEPNG_COMPILE_ENCODER
|
|
|
1157 /* Zlib-compress an unsigned char buffer */
|
|
|
1158 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
|
|
|
1159 const LodePNGCompressSettings& settings = lodepng_default_compress_settings);
|
|
|
1160
|
|
|
1161 /* Zlib-compress an std::vector */
|
|
|
1162 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
|
|
|
1163 const LodePNGCompressSettings& settings = lodepng_default_compress_settings);
|
|
|
1164 #endif /* LODEPNG_COMPILE_ENCODER */
|
|
|
1165 #endif /* LODEPNG_COMPILE_ZLIB */
|
|
|
1166 } /* namespace lodepng */
|
|
|
1167 #endif /*LODEPNG_COMPILE_CPP*/
|
|
|
1168
|
|
|
1169 /*
|
|
|
1170 TODO:
|
|
|
1171 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often
|
|
|
1172 [.] check compatibility with various compilers - done but needs to be redone for every newer version
|
|
|
1173 [X] converting color to 16-bit per channel types
|
|
|
1174 [X] support color profile chunk types (but never let them touch RGB values by default)
|
|
|
1175 [ ] support all public PNG chunk types (almost done except sPLT and hIST)
|
|
|
1176 [ ] make sure encoder generates no chunks with size > (2^31)-1
|
|
|
1177 [ ] partial decoding (stream processing)
|
|
|
1178 [X] let the "isFullyOpaque" function check color keys and transparent palettes too
|
|
|
1179 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl"
|
|
|
1180 [ ] allow treating some errors like warnings, when image is recoverable (e.g. 69, 57, 58)
|
|
|
1181 [ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ...
|
|
|
1182 [ ] error messages with line numbers (and version)
|
|
|
1183 [ ] errors in state instead of as return code?
|
|
|
1184 [ ] new errors/warnings like suspiciously big decompressed ztxt or iccp chunk
|
|
|
1185 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes
|
|
|
1186 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ...
|
|
|
1187 [ ] allow user to give data (void*) to custom allocator
|
|
|
1188 [X] provide alternatives for C library functions not present on some platforms (memcpy, ...)
|
|
|
1189 */
|
|
|
1190
|
|
|
1191 #endif /*LODEPNG_H inclusion guard*/
|
|
|
1192
|
|
|
1193 /*
|
|
|
1194 LodePNG Documentation
|
|
|
1195 ---------------------
|
|
|
1196
|
|
|
1197 0. table of contents
|
|
|
1198 --------------------
|
|
|
1199
|
|
|
1200 1. about
|
|
|
1201 1.1. supported features
|
|
|
1202 1.2. features not supported
|
|
|
1203 2. C and C++ version
|
|
|
1204 3. security
|
|
|
1205 4. decoding
|
|
|
1206 5. encoding
|
|
|
1207 6. color conversions
|
|
|
1208 6.1. PNG color types
|
|
|
1209 6.2. color conversions
|
|
|
1210 6.3. padding bits
|
|
|
1211 6.4. A note about 16-bits per channel and endianness
|
|
|
1212 7. error values
|
|
|
1213 8. chunks and PNG editing
|
|
|
1214 9. compiler support
|
|
|
1215 10. examples
|
|
|
1216 10.1. decoder C++ example
|
|
|
1217 10.2. decoder C example
|
|
|
1218 11. state settings reference
|
|
|
1219 12. changes
|
|
|
1220 13. contact information
|
|
|
1221
|
|
|
1222
|
|
|
1223 1. about
|
|
|
1224 --------
|
|
|
1225
|
|
|
1226 PNG is a file format to store raster images losslessly with good compression,
|
|
|
1227 supporting different color types and alpha channel.
|
|
|
1228
|
|
|
1229 LodePNG is a PNG codec according to the Portable Network Graphics (PNG)
|
|
|
1230 Specification (Second Edition) - W3C Recommendation 10 November 2003.
|
|
|
1231
|
|
|
1232 The specifications used are:
|
|
|
1233
|
|
|
1234 *) Portable Network Graphics (PNG) Specification (Second Edition):
|
|
|
1235 http://www.w3.org/TR/2003/REC-PNG-20031110
|
|
|
1236 *) RFC 1950 ZLIB Compressed Data Format version 3.3:
|
|
|
1237 http://www.gzip.org/zlib/rfc-zlib.html
|
|
|
1238 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3:
|
|
|
1239 http://www.gzip.org/zlib/rfc-deflate.html
|
|
|
1240
|
|
|
1241 The most recent version of LodePNG can currently be found at
|
|
|
1242 http://lodev.org/lodepng/
|
|
|
1243
|
|
|
1244 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds
|
|
|
1245 extra functionality.
|
|
|
1246
|
|
|
1247 LodePNG exists out of two files:
|
|
|
1248 -lodepng.h: the header file for both C and C++
|
|
|
1249 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage
|
|
|
1250
|
|
|
1251 If you want to start using LodePNG right away without reading this doc, get the
|
|
|
1252 examples from the LodePNG website to see how to use it in code, or check the
|
|
|
1253 smaller examples in chapter 13 here.
|
|
|
1254
|
|
|
1255 LodePNG is simple but only supports the basic requirements. To achieve
|
|
|
1256 simplicity, the following design choices were made: There are no dependencies
|
|
|
1257 on any external library. There are functions to decode and encode a PNG with
|
|
|
1258 a single function call, and extended versions of these functions taking a
|
|
|
1259 LodePNGState struct allowing to specify or get more information. By default
|
|
|
1260 the colors of the raw image are always RGB or RGBA, no matter what color type
|
|
|
1261 the PNG file uses. To read and write files, there are simple functions to
|
|
|
1262 convert the files to/from buffers in memory.
|
|
|
1263
|
|
|
1264 This all makes LodePNG suitable for loading textures in games, demos and small
|
|
|
1265 programs, ... It's less suitable for full fledged image editors, loading PNGs
|
|
|
1266 over network (it requires all the image data to be available before decoding can
|
|
|
1267 begin), life-critical systems, ...
|
|
|
1268
|
|
|
1269 1.1. supported features
|
|
|
1270 -----------------------
|
|
|
1271
|
|
|
1272 The following features are supported by the decoder:
|
|
|
1273
|
|
|
1274 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image,
|
|
|
1275 or the same color type as the PNG
|
|
|
1276 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image
|
|
|
1277 *) Adam7 interlace and deinterlace for any color type
|
|
|
1278 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk
|
|
|
1279 *) support for alpha channels, including RGBA color model, translucent palettes and color keying
|
|
|
1280 *) zlib decompression (inflate)
|
|
|
1281 *) zlib compression (deflate)
|
|
|
1282 *) CRC32 and ADLER32 checksums
|
|
|
1283 *) colorimetric color profile conversions: currently experimentally available in lodepng_util.cpp only,
|
|
|
1284 plus alternatively ability to pass on chroma/gamma/ICC profile information to other color management system.
|
|
|
1285 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks.
|
|
|
1286 *) the following chunks are supported by both encoder and decoder:
|
|
|
1287 IHDR: header information
|
|
|
1288 PLTE: color palette
|
|
|
1289 IDAT: pixel data
|
|
|
1290 IEND: the final chunk
|
|
|
1291 tRNS: transparency for palettized images
|
|
|
1292 tEXt: textual information
|
|
|
1293 zTXt: compressed textual information
|
|
|
1294 iTXt: international textual information
|
|
|
1295 bKGD: suggested background color
|
|
|
1296 pHYs: physical dimensions
|
|
|
1297 tIME: modification time
|
|
|
1298 cHRM: RGB chromaticities
|
|
|
1299 gAMA: RGB gamma correction
|
|
|
1300 iCCP: ICC color profile
|
|
|
1301 sRGB: rendering intent
|
|
|
1302 sBIT: significant bits
|
|
|
1303
|
|
|
1304 1.2. features not supported
|
|
|
1305 ---------------------------
|
|
|
1306
|
|
|
1307 The following features are not (yet) supported:
|
|
|
1308
|
|
|
1309 *) some features needed to make a conformant PNG-Editor might be still missing.
|
|
|
1310 *) partial loading/stream processing. All data must be available and is processed in one call.
|
|
|
1311 *) The hIST and sPLT public chunks are not (yet) supported but treated as unknown chunks
|
|
|
1312
|
|
|
1313
|
|
|
1314 2. C and C++ version
|
|
|
1315 --------------------
|
|
|
1316
|
|
|
1317 The C version uses buffers allocated with alloc that you need to free()
|
|
|
1318 yourself. You need to use init and cleanup functions for each struct whenever
|
|
|
1319 using a struct from the C version to avoid exploits and memory leaks.
|
|
|
1320
|
|
|
1321 The C++ version has extra functions with std::vectors in the interface and the
|
|
|
1322 lodepng::State class which is a LodePNGState with constructor and destructor.
|
|
|
1323
|
|
|
1324 These files work without modification for both C and C++ compilers because all
|
|
|
1325 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers
|
|
|
1326 ignore it, and the C code is made to compile both with strict ISO C90 and C++.
|
|
|
1327
|
|
|
1328 To use the C++ version, you need to rename the source file to lodepng.cpp
|
|
|
1329 (instead of lodepng.c), and compile it with a C++ compiler.
|
|
|
1330
|
|
|
1331 To use the C version, you need to rename the source file to lodepng.c (instead
|
|
|
1332 of lodepng.cpp), and compile it with a C compiler.
|
|
|
1333
|
|
|
1334
|
|
|
1335 3. Security
|
|
|
1336 -----------
|
|
|
1337
|
|
|
1338 Even if carefully designed, it's always possible that LodePNG contains possible
|
|
|
1339 exploits. If you discover one, please let me know, and it will be fixed.
|
|
|
1340
|
|
|
1341 When using LodePNG, care has to be taken with the C version of LodePNG, as well
|
|
|
1342 as the C-style structs when working with C++. The following conventions are used
|
|
|
1343 for all C-style structs:
|
|
|
1344
|
|
|
1345 -if a struct has a corresponding init function, always call the init function when making a new one
|
|
|
1346 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks
|
|
|
1347 -if a struct has a corresponding copy function, use the copy function instead of "=".
|
|
|
1348 The destination must also be inited already.
|
|
|
1349
|
|
|
1350
|
|
|
1351 4. Decoding
|
|
|
1352 -----------
|
|
|
1353
|
|
|
1354 Decoding converts a PNG compressed image to a raw pixel buffer.
|
|
|
1355
|
|
|
1356 Most documentation on using the decoder is at its declarations in the header
|
|
|
1357 above. For C, simple decoding can be done with functions such as
|
|
|
1358 lodepng_decode32, and more advanced decoding can be done with the struct
|
|
|
1359 LodePNGState and lodepng_decode. For C++, all decoding can be done with the
|
|
|
1360 various lodepng::decode functions, and lodepng::State can be used for advanced
|
|
|
1361 features.
|
|
|
1362
|
|
|
1363 When using the LodePNGState, it uses the following fields for decoding:
|
|
|
1364 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here
|
|
|
1365 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get
|
|
|
1366 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use
|
|
|
1367
|
|
|
1368 LodePNGInfo info_png
|
|
|
1369 --------------------
|
|
|
1370
|
|
|
1371 After decoding, this contains extra information of the PNG image, except the actual
|
|
|
1372 pixels, width and height because these are already gotten directly from the decoder
|
|
|
1373 functions.
|
|
|
1374
|
|
|
1375 It contains for example the original color type of the PNG image, text comments,
|
|
|
1376 suggested background color, etc... More details about the LodePNGInfo struct are
|
|
|
1377 at its declaration documentation.
|
|
|
1378
|
|
|
1379 LodePNGColorMode info_raw
|
|
|
1380 -------------------------
|
|
|
1381
|
|
|
1382 When decoding, here you can specify which color type you want
|
|
|
1383 the resulting raw image to be. If this is different from the colortype of the
|
|
|
1384 PNG, then the decoder will automatically convert the result. This conversion
|
|
|
1385 always works, except if you want it to convert a color PNG to grayscale or to
|
|
|
1386 a palette with missing colors.
|
|
|
1387
|
|
|
1388 By default, 32-bit color is used for the result.
|
|
|
1389
|
|
|
1390 LodePNGDecoderSettings decoder
|
|
|
1391 ------------------------------
|
|
|
1392
|
|
|
1393 The settings can be used to ignore the errors created by invalid CRC and Adler32
|
|
|
1394 chunks, and to disable the decoding of tEXt chunks.
|
|
|
1395
|
|
|
1396 There's also a setting color_convert, true by default. If false, no conversion
|
|
|
1397 is done, the resulting data will be as it was in the PNG (after decompression)
|
|
|
1398 and you'll have to puzzle the colors of the pixels together yourself using the
|
|
|
1399 color type information in the LodePNGInfo.
|
|
|
1400
|
|
|
1401
|
|
|
1402 5. Encoding
|
|
|
1403 -----------
|
|
|
1404
|
|
|
1405 Encoding converts a raw pixel buffer to a PNG compressed image.
|
|
|
1406
|
|
|
1407 Most documentation on using the encoder is at its declarations in the header
|
|
|
1408 above. For C, simple encoding can be done with functions such as
|
|
|
1409 lodepng_encode32, and more advanced decoding can be done with the struct
|
|
|
1410 LodePNGState and lodepng_encode. For C++, all encoding can be done with the
|
|
|
1411 various lodepng::encode functions, and lodepng::State can be used for advanced
|
|
|
1412 features.
|
|
|
1413
|
|
|
1414 Like the decoder, the encoder can also give errors. However it gives less errors
|
|
|
1415 since the encoder input is trusted, the decoder input (a PNG image that could
|
|
|
1416 be forged by anyone) is not trusted.
|
|
|
1417
|
|
|
1418 When using the LodePNGState, it uses the following fields for encoding:
|
|
|
1419 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be.
|
|
|
1420 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has
|
|
|
1421 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use
|
|
|
1422
|
|
|
1423 LodePNGInfo info_png
|
|
|
1424 --------------------
|
|
|
1425
|
|
|
1426 When encoding, you use this the opposite way as when decoding: for encoding,
|
|
|
1427 you fill in the values you want the PNG to have before encoding. By default it's
|
|
|
1428 not needed to specify a color type for the PNG since it's automatically chosen,
|
|
|
1429 but it's possible to choose it yourself given the right settings.
|
|
|
1430
|
|
|
1431 The encoder will not always exactly match the LodePNGInfo struct you give,
|
|
|
1432 it tries as close as possible. Some things are ignored by the encoder. The
|
|
|
1433 encoder uses, for example, the following settings from it when applicable:
|
|
|
1434 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the
|
|
|
1435 background color, the interlace method, unknown chunks, ...
|
|
|
1436
|
|
|
1437 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk.
|
|
|
1438 If the palette contains any colors for which the alpha channel is not 255 (so
|
|
|
1439 there are translucent colors in the palette), it'll add a tRNS chunk.
|
|
|
1440
|
|
|
1441 LodePNGColorMode info_raw
|
|
|
1442 -------------------------
|
|
|
1443
|
|
|
1444 You specify the color type of the raw image that you give to the input here,
|
|
|
1445 including a possible transparent color key and palette you happen to be using in
|
|
|
1446 your raw image data.
|
|
|
1447
|
|
|
1448 By default, 32-bit color is assumed, meaning your input has to be in RGBA
|
|
|
1449 format with 4 bytes (unsigned chars) per pixel.
|
|
|
1450
|
|
|
1451 LodePNGEncoderSettings encoder
|
|
|
1452 ------------------------------
|
|
|
1453
|
|
|
1454 The following settings are supported (some are in sub-structs):
|
|
|
1455 *) auto_convert: when this option is enabled, the encoder will
|
|
|
1456 automatically choose the smallest possible color mode (including color key) that
|
|
|
1457 can encode the colors of all pixels without information loss.
|
|
|
1458 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree,
|
|
|
1459 2 = dynamic huffman tree (best compression). Should be 2 for proper
|
|
|
1460 compression.
|
|
|
1461 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be
|
|
|
1462 true for proper compression.
|
|
|
1463 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value
|
|
|
1464 2048 by default, but can be set to 32768 for better, but slow, compression.
|
|
|
1465 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE
|
|
|
1466 chunk if force_palette is true. This can used as suggested palette to convert
|
|
|
1467 to by viewers that don't support more than 256 colors (if those still exist)
|
|
|
1468 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image.
|
|
|
1469 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks.
|
|
|
1470 zTXt chunks use zlib compression on the text. This gives a smaller result on
|
|
|
1471 large texts but a larger result on small texts (such as a single program name).
|
|
|
1472 It's all tEXt or all zTXt though, there's no separate setting per text yet.
|
|
|
1473
|
|
|
1474
|
|
|
1475 6. color conversions
|
|
|
1476 --------------------
|
|
|
1477
|
|
|
1478 An important thing to note about LodePNG, is that the color type of the PNG, and
|
|
|
1479 the color type of the raw image, are completely independent. By default, when
|
|
|
1480 you decode a PNG, you get the result as a raw image in the color type you want,
|
|
|
1481 no matter whether the PNG was encoded with a palette, grayscale or RGBA color.
|
|
|
1482 And if you encode an image, by default LodePNG will automatically choose the PNG
|
|
|
1483 color type that gives good compression based on the values of colors and amount
|
|
|
1484 of colors in the image. It can be configured to let you control it instead as
|
|
|
1485 well, though.
|
|
|
1486
|
|
|
1487 To be able to do this, LodePNG does conversions from one color mode to another.
|
|
|
1488 It can convert from almost any color type to any other color type, except the
|
|
|
1489 following conversions: RGB to grayscale is not supported, and converting to a
|
|
|
1490 palette when the palette doesn't have a required color is not supported. This is
|
|
|
1491 not supported on purpose: this is information loss which requires a color
|
|
|
1492 reduction algorithm that is beyond the scope of a PNG encoder (yes, RGB to gray
|
|
|
1493 is easy, but there are multiple ways if you want to give some channels more
|
|
|
1494 weight).
|
|
|
1495
|
|
|
1496 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB
|
|
|
1497 color, no matter what color type the PNG has. And by default when encoding,
|
|
|
1498 LodePNG automatically picks the best color model for the output PNG, and expects
|
|
|
1499 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control
|
|
|
1500 the color format of the images yourself, you can skip this chapter.
|
|
|
1501
|
|
|
1502 6.1. PNG color types
|
|
|
1503 --------------------
|
|
|
1504
|
|
|
1505 A PNG image can have many color types, ranging from 1-bit color to 64-bit color,
|
|
|
1506 as well as palettized color modes. After the zlib decompression and unfiltering
|
|
|
1507 in the PNG image is done, the raw pixel data will have that color type and thus
|
|
|
1508 a certain amount of bits per pixel. If you want the output raw image after
|
|
|
1509 decoding to have another color type, a conversion is done by LodePNG.
|
|
|
1510
|
|
|
1511 The PNG specification gives the following color types:
|
|
|
1512
|
|
|
1513 0: grayscale, bit depths 1, 2, 4, 8, 16
|
|
|
1514 2: RGB, bit depths 8 and 16
|
|
|
1515 3: palette, bit depths 1, 2, 4 and 8
|
|
|
1516 4: grayscale with alpha, bit depths 8 and 16
|
|
|
1517 6: RGBA, bit depths 8 and 16
|
|
|
1518
|
|
|
1519 Bit depth is the amount of bits per pixel per color channel. So the total amount
|
|
|
1520 of bits per pixel is: amount of channels * bitdepth.
|
|
|
1521
|
|
|
1522 6.2. color conversions
|
|
|
1523 ----------------------
|
|
|
1524
|
|
|
1525 As explained in the sections about the encoder and decoder, you can specify
|
|
|
1526 color types and bit depths in info_png and info_raw to change the default
|
|
|
1527 behaviour.
|
|
|
1528
|
|
|
1529 If, when decoding, you want the raw image to be something else than the default,
|
|
|
1530 you need to set the color type and bit depth you want in the LodePNGColorMode,
|
|
|
1531 or the parameters colortype and bitdepth of the simple decoding function.
|
|
|
1532
|
|
|
1533 If, when encoding, you use another color type than the default in the raw input
|
|
|
1534 image, you need to specify its color type and bit depth in the LodePNGColorMode
|
|
|
1535 of the raw image, or use the parameters colortype and bitdepth of the simple
|
|
|
1536 encoding function.
|
|
|
1537
|
|
|
1538 If, when encoding, you don't want LodePNG to choose the output PNG color type
|
|
|
1539 but control it yourself, you need to set auto_convert in the encoder settings
|
|
|
1540 to false, and specify the color type you want in the LodePNGInfo of the
|
|
|
1541 encoder (including palette: it can generate a palette if auto_convert is true,
|
|
|
1542 otherwise not).
|
|
|
1543
|
|
|
1544 If the input and output color type differ (whether user chosen or auto chosen),
|
|
|
1545 LodePNG will do a color conversion, which follows the rules below, and may
|
|
|
1546 sometimes result in an error.
|
|
|
1547
|
|
|
1548 To avoid some confusion:
|
|
|
1549 -the decoder converts from PNG to raw image
|
|
|
1550 -the encoder converts from raw image to PNG
|
|
|
1551 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image
|
|
|
1552 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG
|
|
|
1553 -when encoding, the color type in LodePNGInfo is ignored if auto_convert
|
|
|
1554 is enabled, it is automatically generated instead
|
|
|
1555 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original
|
|
|
1556 PNG image, but it can be ignored since the raw image has the color type you requested instead
|
|
|
1557 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion
|
|
|
1558 between the color types is done if the color types are supported. If it is not
|
|
|
1559 supported, an error is returned. If the types are the same, no conversion is done.
|
|
|
1560 -even though some conversions aren't supported, LodePNG supports loading PNGs from any
|
|
|
1561 colortype and saving PNGs to any colortype, sometimes it just requires preparing
|
|
|
1562 the raw image correctly before encoding.
|
|
|
1563 -both encoder and decoder use the same color converter.
|
|
|
1564
|
|
|
1565 The function lodepng_convert does the color conversion. It is available in the
|
|
|
1566 interface but normally isn't needed since the encoder and decoder already call
|
|
|
1567 it.
|
|
|
1568
|
|
|
1569 Non supported color conversions:
|
|
|
1570 -color to grayscale when non-gray pixels are present: no error is thrown, but
|
|
|
1571 the result will look ugly because only the red channel is taken (it assumes all
|
|
|
1572 three channels are the same in this case so ignores green and blue). The reason
|
|
|
1573 no error is given is to allow converting from three-channel grayscale images to
|
|
|
1574 one-channel even if there are numerical imprecisions.
|
|
|
1575 -anything to palette when the palette does not have an exact match for a from-color
|
|
|
1576 in it: in this case an error is thrown
|
|
|
1577
|
|
|
1578 Supported color conversions:
|
|
|
1579 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA
|
|
|
1580 -any gray or gray+alpha, to gray or gray+alpha
|
|
|
1581 -anything to a palette, as long as the palette has the requested colors in it
|
|
|
1582 -removing alpha channel
|
|
|
1583 -higher to smaller bitdepth, and vice versa
|
|
|
1584
|
|
|
1585 If you want no color conversion to be done (e.g. for speed or control):
|
|
|
1586 -In the encoder, you can make it save a PNG with any color type by giving the
|
|
|
1587 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to
|
|
|
1588 false.
|
|
|
1589 -In the decoder, you can make it store the pixel data in the same color type
|
|
|
1590 as the PNG has, by setting the color_convert setting to false. Settings in
|
|
|
1591 info_raw are then ignored.
|
|
|
1592
|
|
|
1593 6.3. padding bits
|
|
|
1594 -----------------
|
|
|
1595
|
|
|
1596 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines
|
|
|
1597 have a bit amount that isn't a multiple of 8, then padding bits are used so that each
|
|
|
1598 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output.
|
|
|
1599 The raw input image you give to the encoder, and the raw output image you get from the decoder
|
|
|
1600 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width
|
|
|
1601 of 7 pixels, the first pixel of the second scanline will the 8th bit of the first byte,
|
|
|
1602 not the first bit of a new byte.
|
|
|
1603
|
|
|
1604 6.4. A note about 16-bits per channel and endianness
|
|
|
1605 ----------------------------------------------------
|
|
|
1606
|
|
|
1607 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like
|
|
|
1608 for any other color format. The 16-bit values are stored in big endian (most
|
|
|
1609 significant byte first) in these arrays. This is the opposite order of the
|
|
|
1610 little endian used by x86 CPU's.
|
|
|
1611
|
|
|
1612 LodePNG always uses big endian because the PNG file format does so internally.
|
|
|
1613 Conversions to other formats than PNG uses internally are not supported by
|
|
|
1614 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit
|
|
|
1615 colors, the order in which you store R, G, B and A, and so on. Supporting and
|
|
|
1616 converting to/from all that is outside the scope of LodePNG.
|
|
|
1617
|
|
|
1618 This may mean that, depending on your use case, you may want to convert the big
|
|
|
1619 endian output of LodePNG to little endian with a for loop. This is certainly not
|
|
|
1620 always needed, many applications and libraries support big endian 16-bit colors
|
|
|
1621 anyway, but it means you cannot simply cast the unsigned char* buffer to an
|
|
|
1622 unsigned short* buffer on x86 CPUs.
|
|
|
1623
|
|
|
1624
|
|
|
1625 7. error values
|
|
|
1626 ---------------
|
|
|
1627
|
|
|
1628 All functions in LodePNG that return an error code, return 0 if everything went
|
|
|
1629 OK, or a non-zero code if there was an error.
|
|
|
1630
|
|
|
1631 The meaning of the LodePNG error values can be retrieved with the function
|
|
|
1632 lodepng_error_text: given the numerical error code, it returns a description
|
|
|
1633 of the error in English as a string.
|
|
|
1634
|
|
|
1635 Check the implementation of lodepng_error_text to see the meaning of each code.
|
|
|
1636
|
|
|
1637 It is not recommended to use the numerical values to programmatically make
|
|
|
1638 different decisions based on error types as the numbers are not guaranteed to
|
|
|
1639 stay backwards compatible. They are for human consumption only. Programmatically
|
|
|
1640 only 0 or non-0 matter.
|
|
|
1641
|
|
|
1642
|
|
|
1643 8. chunks and PNG editing
|
|
|
1644 -------------------------
|
|
|
1645
|
|
|
1646 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG
|
|
|
1647 editor that should follow the rules about handling of unknown chunks, or if your
|
|
|
1648 program is able to read other types of chunks than the ones handled by LodePNG,
|
|
|
1649 then that's possible with the chunk functions of LodePNG.
|
|
|
1650
|
|
|
1651 A PNG chunk has the following layout:
|
|
|
1652
|
|
|
1653 4 bytes length
|
|
|
1654 4 bytes type name
|
|
|
1655 length bytes data
|
|
|
1656 4 bytes CRC
|
|
|
1657
|
|
|
1658 8.1. iterating through chunks
|
|
|
1659 -----------------------------
|
|
|
1660
|
|
|
1661 If you have a buffer containing the PNG image data, then the first chunk (the
|
|
|
1662 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the
|
|
|
1663 signature of the PNG and are not part of a chunk. But if you start at byte 8
|
|
|
1664 then you have a chunk, and can check the following things of it.
|
|
|
1665
|
|
|
1666 NOTE: none of these functions check for memory buffer boundaries. To avoid
|
|
|
1667 exploits, always make sure the buffer contains all the data of the chunks.
|
|
|
1668 When using lodepng_chunk_next, make sure the returned value is within the
|
|
|
1669 allocated memory.
|
|
|
1670
|
|
|
1671 unsigned lodepng_chunk_length(const unsigned char* chunk):
|
|
|
1672
|
|
|
1673 Get the length of the chunk's data. The total chunk length is this length + 12.
|
|
|
1674
|
|
|
1675 void lodepng_chunk_type(char type[5], const unsigned char* chunk):
|
|
|
1676 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type):
|
|
|
1677
|
|
|
1678 Get the type of the chunk or compare if it's a certain type
|
|
|
1679
|
|
|
1680 unsigned char lodepng_chunk_critical(const unsigned char* chunk):
|
|
|
1681 unsigned char lodepng_chunk_private(const unsigned char* chunk):
|
|
|
1682 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk):
|
|
|
1683
|
|
|
1684 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are).
|
|
|
1685 Check if the chunk is private (public chunks are part of the standard, private ones not).
|
|
|
1686 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical
|
|
|
1687 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your
|
|
|
1688 program doesn't handle that type of unknown chunk.
|
|
|
1689
|
|
|
1690 unsigned char* lodepng_chunk_data(unsigned char* chunk):
|
|
|
1691 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk):
|
|
|
1692
|
|
|
1693 Get a pointer to the start of the data of the chunk.
|
|
|
1694
|
|
|
1695 unsigned lodepng_chunk_check_crc(const unsigned char* chunk):
|
|
|
1696 void lodepng_chunk_generate_crc(unsigned char* chunk):
|
|
|
1697
|
|
|
1698 Check if the crc is correct or generate a correct one.
|
|
|
1699
|
|
|
1700 unsigned char* lodepng_chunk_next(unsigned char* chunk):
|
|
|
1701 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk):
|
|
|
1702
|
|
|
1703 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these
|
|
|
1704 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough
|
|
|
1705 data available in the buffer to be able to go to the next chunk.
|
|
|
1706
|
|
|
1707 unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk):
|
|
|
1708 unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length,
|
|
|
1709 const char* type, const unsigned char* data):
|
|
|
1710
|
|
|
1711 These functions are used to create new chunks that are appended to the data in *out that has
|
|
|
1712 length *outsize. The append function appends an existing chunk to the new data. The create
|
|
|
1713 function creates a new chunk with the given parameters and appends it. Type is the 4-letter
|
|
|
1714 name of the chunk.
|
|
|
1715
|
|
|
1716 8.2. chunks in info_png
|
|
|
1717 -----------------------
|
|
|
1718
|
|
|
1719 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3
|
|
|
1720 buffers (each with size) to contain 3 types of unknown chunks:
|
|
|
1721 the ones that come before the PLTE chunk, the ones that come between the PLTE
|
|
|
1722 and the IDAT chunks, and the ones that come after the IDAT chunks.
|
|
|
1723 It's necessary to make the distinction between these 3 cases because the PNG
|
|
|
1724 standard forces to keep the ordering of unknown chunks compared to the critical
|
|
|
1725 chunks, but does not force any other ordering rules.
|
|
|
1726
|
|
|
1727 info_png.unknown_chunks_data[0] is the chunks before PLTE
|
|
|
1728 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT
|
|
|
1729 info_png.unknown_chunks_data[2] is the chunks after IDAT
|
|
|
1730
|
|
|
1731 The chunks in these 3 buffers can be iterated through and read by using the same
|
|
|
1732 way described in the previous subchapter.
|
|
|
1733
|
|
|
1734 When using the decoder to decode a PNG, you can make it store all unknown chunks
|
|
|
1735 if you set the option settings.remember_unknown_chunks to 1. By default, this
|
|
|
1736 option is off (0).
|
|
|
1737
|
|
|
1738 The encoder will always encode unknown chunks that are stored in the info_png.
|
|
|
1739 If you need it to add a particular chunk that isn't known by LodePNG, you can
|
|
|
1740 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in
|
|
|
1741 info_png.unknown_chunks_data[x].
|
|
|
1742
|
|
|
1743 Chunks that are known by LodePNG should not be added in that way. E.g. to make
|
|
|
1744 LodePNG add a bKGD chunk, set background_defined to true and add the correct
|
|
|
1745 parameters there instead.
|
|
|
1746
|
|
|
1747
|
|
|
1748 9. compiler support
|
|
|
1749 -------------------
|
|
|
1750
|
|
|
1751 No libraries other than the current standard C library are needed to compile
|
|
|
1752 LodePNG. For the C++ version, only the standard C++ library is needed on top.
|
|
|
1753 Add the files lodepng.c(pp) and lodepng.h to your project, include
|
|
|
1754 lodepng.h where needed, and your program can read/write PNG files.
|
|
|
1755
|
|
|
1756 It is compatible with C90 and up, and C++03 and up.
|
|
|
1757
|
|
|
1758 If performance is important, use optimization when compiling! For both the
|
|
|
1759 encoder and decoder, this makes a large difference.
|
|
|
1760
|
|
|
1761 Make sure that LodePNG is compiled with the same compiler of the same version
|
|
|
1762 and with the same settings as the rest of the program, or the interfaces with
|
|
|
1763 std::vectors and std::strings in C++ can be incompatible.
|
|
|
1764
|
|
|
1765 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets.
|
|
|
1766
|
|
|
1767 *) gcc and g++
|
|
|
1768
|
|
|
1769 LodePNG is developed in gcc so this compiler is natively supported. It gives no
|
|
|
1770 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++
|
|
|
1771 version 4.7.1 on Linux, 32-bit and 64-bit.
|
|
|
1772
|
|
|
1773 *) Clang
|
|
|
1774
|
|
|
1775 Fully supported and warning-free.
|
|
|
1776
|
|
|
1777 *) Mingw
|
|
|
1778
|
|
|
1779 The Mingw compiler (a port of gcc for Windows) should be fully supported by
|
|
|
1780 LodePNG.
|
|
|
1781
|
|
|
1782 *) Visual Studio and Visual C++ Express Edition
|
|
|
1783
|
|
|
1784 LodePNG should be warning-free with warning level W4. Two warnings were disabled
|
|
|
1785 with pragmas though: warning 4244 about implicit conversions, and warning 4996
|
|
|
1786 where it wants to use a non-standard function fopen_s instead of the standard C
|
|
|
1787 fopen.
|
|
|
1788
|
|
|
1789 Visual Studio may want "stdafx.h" files to be included in each source file and
|
|
|
1790 give an error "unexpected end of file while looking for precompiled header".
|
|
|
1791 This is not standard C++ and will not be added to the stock LodePNG. You can
|
|
|
1792 disable it for lodepng.cpp only by right clicking it, Properties, C/C++,
|
|
|
1793 Precompiled Headers, and set it to Not Using Precompiled Headers there.
|
|
|
1794
|
|
|
1795 NOTE: Modern versions of VS should be fully supported, but old versions, e.g.
|
|
|
1796 VS6, are not guaranteed to work.
|
|
|
1797
|
|
|
1798 *) Compilers on Macintosh
|
|
|
1799
|
|
|
1800 LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for
|
|
|
1801 C and C++.
|
|
|
1802
|
|
|
1803 *) Other Compilers
|
|
|
1804
|
|
|
1805 If you encounter problems on any compilers, feel free to let me know and I may
|
|
|
1806 try to fix it if the compiler is modern and standards compliant.
|
|
|
1807
|
|
|
1808
|
|
|
1809 10. examples
|
|
|
1810 ------------
|
|
|
1811
|
|
|
1812 This decoder example shows the most basic usage of LodePNG. More complex
|
|
|
1813 examples can be found on the LodePNG website.
|
|
|
1814
|
|
|
1815 NOTE: these examples do not support wide-character filenames, you can use an
|
|
|
1816 external method to handle such files and encode or decode in-memory
|
|
|
1817
|
|
|
1818 10.1. decoder C++ example
|
|
|
1819 -------------------------
|
|
|
1820
|
|
|
1821 #include "lodepng.h"
|
|
|
1822 #include <iostream>
|
|
|
1823
|
|
|
1824 int main(int argc, char *argv[]) {
|
|
|
1825 const char* filename = argc > 1 ? argv[1] : "test.png";
|
|
|
1826
|
|
|
1827 //load and decode
|
|
|
1828 std::vector<unsigned char> image;
|
|
|
1829 unsigned width, height;
|
|
|
1830 unsigned error = lodepng::decode(image, width, height, filename);
|
|
|
1831
|
|
|
1832 //if there's an error, display it
|
|
|
1833 if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl;
|
|
|
1834
|
|
|
1835 //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ...
|
|
|
1836 }
|
|
|
1837
|
|
|
1838 10.2. decoder C example
|
|
|
1839 -----------------------
|
|
|
1840
|
|
|
1841 #include "lodepng.h"
|
|
|
1842
|
|
|
1843 int main(int argc, char *argv[]) {
|
|
|
1844 unsigned error;
|
|
|
1845 unsigned char* image;
|
|
|
1846 size_t width, height;
|
|
|
1847 const char* filename = argc > 1 ? argv[1] : "test.png";
|
|
|
1848
|
|
|
1849 error = lodepng_decode32_file(&image, &width, &height, filename);
|
|
|
1850
|
|
|
1851 if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error));
|
|
|
1852
|
|
|
1853 / * use image here * /
|
|
|
1854
|
|
|
1855 free(image);
|
|
|
1856 return 0;
|
|
|
1857 }
|
|
|
1858
|
|
|
1859 11. state settings reference
|
|
|
1860 ----------------------------
|
|
|
1861
|
|
|
1862 A quick reference of some settings to set on the LodePNGState
|
|
|
1863
|
|
|
1864 For decoding:
|
|
|
1865
|
|
|
1866 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums
|
|
|
1867 state.decoder.zlibsettings.custom_...: use custom inflate function
|
|
|
1868 state.decoder.ignore_crc: ignore CRC checksums
|
|
|
1869 state.decoder.ignore_critical: ignore unknown critical chunks
|
|
|
1870 state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors
|
|
|
1871 state.decoder.color_convert: convert internal PNG color to chosen one
|
|
|
1872 state.decoder.read_text_chunks: whether to read in text metadata chunks
|
|
|
1873 state.decoder.remember_unknown_chunks: whether to read in unknown chunks
|
|
|
1874 state.info_raw.colortype: desired color type for decoded image
|
|
|
1875 state.info_raw.bitdepth: desired bit depth for decoded image
|
|
|
1876 state.info_raw....: more color settings, see struct LodePNGColorMode
|
|
|
1877 state.info_png....: no settings for decoder but ouput, see struct LodePNGInfo
|
|
|
1878
|
|
|
1879 For encoding:
|
|
|
1880
|
|
|
1881 state.encoder.zlibsettings.btype: disable compression by setting it to 0
|
|
|
1882 state.encoder.zlibsettings.use_lz77: use LZ77 in compression
|
|
|
1883 state.encoder.zlibsettings.windowsize: tweak LZ77 windowsize
|
|
|
1884 state.encoder.zlibsettings.minmatch: tweak min LZ77 length to match
|
|
|
1885 state.encoder.zlibsettings.nicematch: tweak LZ77 match where to stop searching
|
|
|
1886 state.encoder.zlibsettings.lazymatching: try one more LZ77 matching
|
|
|
1887 state.encoder.zlibsettings.custom_...: use custom deflate function
|
|
|
1888 state.encoder.auto_convert: choose optimal PNG color type, if 0 uses info_png
|
|
|
1889 state.encoder.filter_palette_zero: PNG filter strategy for palette
|
|
|
1890 state.encoder.filter_strategy: PNG filter strategy to encode with
|
|
|
1891 state.encoder.force_palette: add palette even if not encoding to one
|
|
|
1892 state.encoder.add_id: add LodePNG identifier and version as a text chunk
|
|
|
1893 state.encoder.text_compression: use compressed text chunks for metadata
|
|
|
1894 state.info_raw.colortype: color type of raw input image you provide
|
|
|
1895 state.info_raw.bitdepth: bit depth of raw input image you provide
|
|
|
1896 state.info_raw: more color settings, see struct LodePNGColorMode
|
|
|
1897 state.info_png.color.colortype: desired color type if auto_convert is false
|
|
|
1898 state.info_png.color.bitdepth: desired bit depth if auto_convert is false
|
|
|
1899 state.info_png.color....: more color settings, see struct LodePNGColorMode
|
|
|
1900 state.info_png....: more PNG related settings, see struct LodePNGInfo
|
|
|
1901
|
|
|
1902
|
|
|
1903 12. changes
|
|
|
1904 -----------
|
|
|
1905
|
|
|
1906 The version number of LodePNG is the date of the change given in the format
|
|
|
1907 yyyymmdd.
|
|
|
1908
|
|
|
1909 Some changes aren't backwards compatible. Those are indicated with a (!)
|
|
|
1910 symbol.
|
|
|
1911
|
|
|
1912 Not all changes are listed here, the commit history in github lists more:
|
|
|
1913 https://github.com/lvandeve/lodepng
|
|
|
1914
|
|
|
1915 *) 10 apr 2023: faster CRC32 implementation, but with larger lookup table.
|
|
|
1916 *) 13 jun 2022: added support for the sBIT chunk.
|
|
|
1917 *) 09 jan 2022: minor decoder speed improvements.
|
|
|
1918 *) 27 jun 2021: added warnings that file reading/writing functions don't support
|
|
|
1919 wide-character filenames (support for this is not planned, opening files is
|
|
|
1920 not the core part of PNG decoding/decoding and is platform dependent).
|
|
|
1921 *) 17 okt 2020: prevent decoding too large text/icc chunks by default.
|
|
|
1922 *) 06 mar 2020: simplified some of the dynamic memory allocations.
|
|
|
1923 *) 12 jan 2020: (!) added 'end' argument to lodepng_chunk_next to allow correct
|
|
|
1924 overflow checks.
|
|
|
1925 *) 14 aug 2019: around 25% faster decoding thanks to huffman lookup tables.
|
|
|
1926 *) 15 jun 2019: (!) auto_choose_color API changed (for bugfix: don't use palette
|
|
|
1927 if gray ICC profile) and non-ICC LodePNGColorProfile renamed to
|
|
|
1928 LodePNGColorStats.
|
|
|
1929 *) 30 dec 2018: code style changes only: removed newlines before opening braces.
|
|
|
1930 *) 10 sep 2018: added way to inspect metadata chunks without full decoding.
|
|
|
1931 *) 19 aug 2018: (!) fixed color mode bKGD is encoded with and made it use
|
|
|
1932 palette index in case of palette.
|
|
|
1933 *) 10 aug 2018: (!) added support for gAMA, cHRM, sRGB and iCCP chunks. This
|
|
|
1934 change is backwards compatible unless you relied on unknown_chunks for those.
|
|
|
1935 *) 11 jun 2018: less restrictive check for pixel size integer overflow
|
|
|
1936 *) 14 jan 2018: allow optionally ignoring a few more recoverable errors
|
|
|
1937 *) 17 sep 2017: fix memory leak for some encoder input error cases
|
|
|
1938 *) 27 nov 2016: grey+alpha auto color model detection bugfix
|
|
|
1939 *) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort).
|
|
|
1940 *) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within
|
|
|
1941 the limits of pure C90).
|
|
|
1942 *) 08 dec 2015: Made load_file function return error if file can't be opened.
|
|
|
1943 *) 24 okt 2015: Bugfix with decoding to palette output.
|
|
|
1944 *) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding.
|
|
|
1945 *) 24 aug 2014: Moved to github
|
|
|
1946 *) 23 aug 2014: Reduced needless memory usage of decoder.
|
|
|
1947 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for
|
|
|
1948 simplicity. Made ColorProfile public.
|
|
|
1949 *) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization.
|
|
|
1950 *) 22 dec 2013: Power of two windowsize required for optimization.
|
|
|
1951 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key.
|
|
|
1952 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png).
|
|
|
1953 *) 11 mar 2013: (!) Bugfix with custom free. Changed from "my" to "lodepng_"
|
|
|
1954 prefix for the custom allocators and made it possible with a new #define to
|
|
|
1955 use custom ones in your project without needing to change lodepng's code.
|
|
|
1956 *) 28 jan 2013: Bugfix with color key.
|
|
|
1957 *) 27 okt 2012: Tweaks in text chunk keyword length error handling.
|
|
|
1958 *) 8 okt 2012: (!) Added new filter strategy (entropy) and new auto color mode.
|
|
|
1959 (no palette). Better deflate tree encoding. New compression tweak settings.
|
|
|
1960 Faster color conversions while decoding. Some internal cleanups.
|
|
|
1961 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit.
|
|
|
1962 *) 1 sep 2012: (!) Removed #define's for giving custom (de)compression functions
|
|
|
1963 and made it work with function pointers instead.
|
|
|
1964 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc
|
|
|
1965 and free functions and toggle #defines from compiler flags. Small fixes.
|
|
|
1966 *) 6 may 2012: (!) Made plugging in custom zlib/deflate functions more flexible.
|
|
|
1967 *) 22 apr 2012: (!) Made interface more consistent, renaming a lot. Removed
|
|
|
1968 redundant C++ codec classes. Reduced amount of structs. Everything changed,
|
|
|
1969 but it is cleaner now imho and functionality remains the same. Also fixed
|
|
|
1970 several bugs and shrunk the implementation code. Made new samples.
|
|
|
1971 *) 6 nov 2011: (!) By default, the encoder now automatically chooses the best
|
|
|
1972 PNG color model and bit depth, based on the amount and type of colors of the
|
|
|
1973 raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color.
|
|
|
1974 *) 9 okt 2011: simpler hash chain implementation for the encoder.
|
|
|
1975 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching.
|
|
|
1976 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking.
|
|
|
1977 A bug with the PNG filtertype heuristic was fixed, so that it chooses much
|
|
|
1978 better ones (it's quite significant). A setting to do an experimental, slow,
|
|
|
1979 brute force search for PNG filter types is added.
|
|
|
1980 *) 17 aug 2011: (!) changed some C zlib related function names.
|
|
|
1981 *) 16 aug 2011: made the code less wide (max 120 characters per line).
|
|
|
1982 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors.
|
|
|
1983 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled.
|
|
|
1984 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman
|
|
|
1985 to optimize long sequences of zeros.
|
|
|
1986 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and
|
|
|
1987 LodePNG_InfoColor_canHaveAlpha functions for convenience.
|
|
|
1988 *) 7 nov 2010: added LodePNG_error_text function to get error code description.
|
|
|
1989 *) 30 okt 2010: made decoding slightly faster
|
|
|
1990 *) 26 okt 2010: (!) changed some C function and struct names (more consistent).
|
|
|
1991 Reorganized the documentation and the declaration order in the header.
|
|
|
1992 *) 08 aug 2010: only changed some comments and external samples.
|
|
|
1993 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version.
|
|
|
1994 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers.
|
|
|
1995 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could
|
|
|
1996 read by ignoring the problem but windows apps couldn't.
|
|
|
1997 *) 06 jun 2008: added more error checks for out of memory cases.
|
|
|
1998 *) 26 apr 2008: added a few more checks here and there to ensure more safety.
|
|
|
1999 *) 06 mar 2008: crash with encoding of strings fixed
|
|
|
2000 *) 02 feb 2008: support for international text chunks added (iTXt)
|
|
|
2001 *) 23 jan 2008: small cleanups, and #defines to divide code in sections
|
|
|
2002 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor.
|
|
|
2003 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder.
|
|
|
2004 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added
|
|
|
2005 Also various fixes, such as in the deflate and the padding bits code.
|
|
|
2006 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved
|
|
|
2007 filtering code of encoder.
|
|
|
2008 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A
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2009 C++ wrapper around this provides an interface almost identical to before.
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2010 Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code
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2011 are together in these files but it works both for C and C++ compilers.
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2012 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks
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2013 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible
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2014 *) 09 aug 2007: some VS2005 warnings removed again
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2015 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code
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2016 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images
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2017 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing
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2018 invalid std::vector element [0] fixed, and level 3 and 4 warnings removed
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2019 *) 02 jun 2007: made the encoder add a tag with version by default
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2020 *) 27 may 2007: zlib and png code separated (but still in the same file),
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2021 simple encoder/decoder functions added for more simple usage cases
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2022 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69),
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2023 moved some examples from here to lodepng_examples.cpp
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2024 *) 12 may 2007: palette decoding bug fixed
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2025 *) 24 apr 2007: changed the license from BSD to the zlib license
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2026 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks.
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2027 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding
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2028 palettized PNG images. Plus little interface change with palette and texts.
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2029 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes.
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2030 Fixed a bug where the end code of a block had length 0 in the Huffman tree.
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2031 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented
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2032 and supported by the encoder, resulting in smaller PNGs at the output.
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2033 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone.
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2034 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any
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2035 greyscale type to 8-bit greyscale with or without alpha.
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2036 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types
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2037 to convert to and is more uniform. See the manual for how it works now.
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2038 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days:
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2039 encode/decode custom tEXt chunks, separate classes for zlib & deflate, and
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2040 at last made the decoder give errors for incorrect Adler32 or Crc.
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2041 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel.
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2042 *) 29 dec 2006: Added support for encoding images without alpha channel, and
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2043 cleaned out code as well as making certain parts faster.
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2044 *) 28 dec 2006: Added "Settings" to the encoder.
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2045 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now.
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2046 Removed some code duplication in the decoder. Fixed little bug in an example.
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2047 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter.
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2048 Fixed a bug of the decoder with 16-bit per color.
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2049 *) 15 okt 2006: Changed documentation structure
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2050 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the
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2051 given image buffer, however for now it's not compressed.
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2052 *) 08 sep 2006: (!) Changed to interface with a Decoder class
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2053 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different
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2054 way. Renamed decodePNG to decodePNGGeneric.
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2055 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a
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2056 struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy.
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2057 *) 28 jul 2006: Cleaned the code and added new error checks.
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2058 Corrected terminology "deflate" into "inflate".
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2059 *) 23 jun 2006: Added SDL example in the documentation in the header, this
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2060 example allows easy debugging by displaying the PNG and its transparency.
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2061 *) 22 jun 2006: (!) Changed way to obtain error value. Added
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2062 loadFile function for convenience. Made decodePNG32 faster.
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2063 *) 21 jun 2006: (!) Changed type of info vector to unsigned.
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2064 Changed position of palette in info vector. Fixed an important bug that
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2065 happened on PNGs with an uncompressed block.
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2066 *) 16 jun 2006: Internally changed unsigned into unsigned where
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2067 needed, and performed some optimizations.
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2068 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them
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2069 in LodePNG namespace. Changed the order of the parameters. Rewrote the
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2070 documentation in the header. Renamed files to lodepng.cpp and lodepng.h
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2071 *) 22 apr 2006: Optimized and improved some code
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2072 *) 07 sep 2005: (!) Changed to std::vector interface
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2073 *) 12 aug 2005: Initial release (C++, decoder only)
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2074
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2075
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2076 13. contact information
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2077 -----------------------
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2078
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2079 Feel free to contact me with suggestions, problems, comments, ... concerning
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2080 LodePNG. If you encounter a PNG image that doesn't work properly with this
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2081 decoder, feel free to send it and I'll use it to find and fix the problem.
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2082
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2083 My email address is (puzzle the account and domain together with an @ symbol):
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2084 Domain: gmail dot com.
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2085 Account: lode dot vandevenne.
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2086
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2087
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2088 Copyright (c) 2005-2022 Lode Vandevenne
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2089 */
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