1 /* 2 LodePNG version 20201017 3 4 Copyright (c) 2005-2020 Lode Vandevenne 5 6 This software is provided 'as-is', without any express or implied 7 warranty. In no event will the authors be held liable for any damages 8 arising from the use of this software. 9 10 Permission is granted to anyone to use this software for any purpose, 11 including commercial applications, and to alter it and redistribute it 12 freely, subject to the following restrictions: 13 14 1. The origin of this software must not be misrepresented; you must not 15 claim that you wrote the original software. If you use this software 16 in a product, an acknowledgment in the product documentation would be 17 appreciated but is not required. 18 19 2. Altered source versions must be plainly marked as such, and must not be 20 misrepresented as being the original software. 21 22 3. This notice may not be removed or altered from any source 23 distribution. 24 */ 25 26 #ifndef LODEPNG_H 27 #define LODEPNG_H 28 29 #include <string.h> /*for size_t*/ 30 31 extern const char* LODEPNG_VERSION_STRING; 32 33 /* 34 The following #defines are used to create code sections. They can be disabled 35 to disable code sections, which can give faster compile time and smaller binary. 36 The "NO_COMPILE" defines are designed to be used to pass as defines to the 37 compiler command to disable them without modifying this header, e.g. 38 -DLODEPNG_NO_COMPILE_ZLIB for gcc. 39 In addition to those below, you can also define LODEPNG_NO_COMPILE_CRC to 40 allow implementing a custom lodepng_crc32. 41 */ 42 /*deflate & zlib. If disabled, you must specify alternative zlib functions in 43 the custom_zlib field of the compress and decompress settings*/ 44 #ifndef LODEPNG_NO_COMPILE_ZLIB 45 #define LODEPNG_COMPILE_ZLIB 46 #endif 47 48 /*png encoder and png decoder*/ 49 #ifndef LODEPNG_NO_COMPILE_PNG 50 #define LODEPNG_COMPILE_PNG 51 #endif 52 53 /*deflate&zlib decoder and png decoder*/ 54 #ifndef LODEPNG_NO_COMPILE_DECODER 55 #define LODEPNG_COMPILE_DECODER 56 #endif 57 58 /*deflate&zlib encoder and png encoder*/ 59 #ifndef LODEPNG_NO_COMPILE_ENCODER 60 #define LODEPNG_COMPILE_ENCODER 61 #endif 62 63 /*the optional built in harddisk file loading and saving functions*/ 64 #ifndef LODEPNG_NO_COMPILE_DISK 65 #define LODEPNG_COMPILE_DISK 66 #endif 67 68 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/ 69 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS 70 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS 71 #endif 72 73 /*ability to convert error numerical codes to English text string*/ 74 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT 75 #define LODEPNG_COMPILE_ERROR_TEXT 76 #endif 77 78 /*Compile the default allocators (C's free, malloc and realloc). If you disable this, 79 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your 80 source files with custom allocators.*/ 81 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS 82 #define LODEPNG_COMPILE_ALLOCATORS 83 #endif 84 85 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/ 86 #ifdef __cplusplus 87 #ifndef LODEPNG_NO_COMPILE_CPP 88 #define LODEPNG_COMPILE_CPP 89 #endif 90 #endif 91 92 #ifdef LODEPNG_COMPILE_CPP 93 #include <vector> 94 #include <string> 95 #endif /*LODEPNG_COMPILE_CPP*/ 96 97 #ifdef LODEPNG_COMPILE_PNG 98 /*The PNG color types (also used for raw image).*/ 99 typedef enum LodePNGColorType { 100 LCT_GREY = 0, /*grayscale: 1,2,4,8,16 bit*/ 101 LCT_RGB = 2, /*RGB: 8,16 bit*/ 102 LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/ 103 LCT_GREY_ALPHA = 4, /*grayscale with alpha: 8,16 bit*/ 104 LCT_RGBA = 6, /*RGB with alpha: 8,16 bit*/ 105 /*LCT_MAX_OCTET_VALUE lets the compiler allow this enum to represent any invalid 106 byte value from 0 to 255 that could be present in an invalid PNG file header. Do 107 not use, compare with or set the name LCT_MAX_OCTET_VALUE, instead either use 108 the valid color type names above, or numeric values like 1 or 7 when checking for 109 particular disallowed color type byte values, or cast to integer to print it.*/ 110 LCT_MAX_OCTET_VALUE = 255 111 } LodePNGColorType; 112 113 #ifdef LODEPNG_COMPILE_DECODER 114 /* 115 Converts PNG data in memory to raw pixel data. 116 out: Output parameter. Pointer to buffer that will contain the raw pixel data. 117 After decoding, its size is w * h * (bytes per pixel) bytes larger than 118 initially. Bytes per pixel depends on colortype and bitdepth. 119 Must be freed after usage with free(*out). 120 Note: for 16-bit per channel colors, uses big endian format like PNG does. 121 w: Output parameter. Pointer to width of pixel data. 122 h: Output parameter. Pointer to height of pixel data. 123 in: Memory buffer with the PNG file. 124 insize: size of the in buffer. 125 colortype: the desired color type for the raw output image. See explanation on PNG color types. 126 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types. 127 Return value: LodePNG error code (0 means no error). 128 */ 129 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, 130 const unsigned char* in, size_t insize, 131 LodePNGColorType colortype, unsigned bitdepth); 132 133 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/ 134 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, 135 const unsigned char* in, size_t insize); 136 137 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/ 138 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, 139 const unsigned char* in, size_t insize); 140 141 #ifdef LODEPNG_COMPILE_DISK 142 /* 143 Load PNG from disk, from file with given name. 144 Same as the other decode functions, but instead takes a filename as input. 145 */ 146 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, 147 const char* filename, 148 LodePNGColorType colortype, unsigned bitdepth); 149 150 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.*/ 151 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, 152 const char* filename); 153 154 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.*/ 155 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, 156 const char* filename); 157 #endif /*LODEPNG_COMPILE_DISK*/ 158 #endif /*LODEPNG_COMPILE_DECODER*/ 159 160 161 #ifdef LODEPNG_COMPILE_ENCODER 162 /* 163 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth 164 of the output PNG image cannot be chosen, they are automatically determined 165 by the colortype, bitdepth and content of the input pixel data. 166 Note: for 16-bit per channel colors, needs big endian format like PNG does. 167 out: Output parameter. Pointer to buffer that will contain the PNG image data. 168 Must be freed after usage with free(*out). 169 outsize: Output parameter. Pointer to the size in bytes of the out buffer. 170 image: The raw pixel data to encode. The size of this buffer should be 171 w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth. 172 w: width of the raw pixel data in pixels. 173 h: height of the raw pixel data in pixels. 174 colortype: the color type of the raw input image. See explanation on PNG color types. 175 bitdepth: the bit depth of the raw input image. See explanation on PNG color types. 176 Return value: LodePNG error code (0 means no error). 177 */ 178 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, 179 const unsigned char* image, unsigned w, unsigned h, 180 LodePNGColorType colortype, unsigned bitdepth); 181 182 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/ 183 unsigned lodepng_encode32(unsigned char** out, size_t* outsize, 184 const unsigned char* image, unsigned w, unsigned h); 185 186 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/ 187 unsigned lodepng_encode24(unsigned char** out, size_t* outsize, 188 const unsigned char* image, unsigned w, unsigned h); 189 190 #ifdef LODEPNG_COMPILE_DISK 191 /* 192 Converts raw pixel data into a PNG file on disk. 193 Same as the other encode functions, but instead takes a filename as output. 194 NOTE: This overwrites existing files without warning! 195 */ 196 unsigned lodepng_encode_file(const char* filename, 197 const unsigned char* image, unsigned w, unsigned h, 198 LodePNGColorType colortype, unsigned bitdepth); 199 200 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.*/ 201 unsigned lodepng_encode32_file(const char* filename, 202 const unsigned char* image, unsigned w, unsigned h); 203 204 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.*/ 205 unsigned lodepng_encode24_file(const char* filename, 206 const unsigned char* image, unsigned w, unsigned h); 207 #endif /*LODEPNG_COMPILE_DISK*/ 208 #endif /*LODEPNG_COMPILE_ENCODER*/ 209 210 211 #ifdef LODEPNG_COMPILE_CPP 212 namespace lodepng { 213 #ifdef LODEPNG_COMPILE_DECODER 214 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype 215 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/ 216 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 217 const unsigned char* in, size_t insize, 218 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 219 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 220 const std::vector<unsigned char>& in, 221 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 222 #ifdef LODEPNG_COMPILE_DISK 223 /* 224 Converts PNG file from disk to raw pixel data in memory. 225 Same as the other decode functions, but instead takes a filename as input. 226 */ 227 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 228 const std::string& filename, 229 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 230 #endif /* LODEPNG_COMPILE_DISK */ 231 #endif /* LODEPNG_COMPILE_DECODER */ 232 233 #ifdef LODEPNG_COMPILE_ENCODER 234 /*Same as lodepng_encode_memory, but encodes to an std::vector. colortype 235 is that of the raw input data. The output PNG color type will be auto chosen.*/ 236 unsigned encode(std::vector<unsigned char>& out, 237 const unsigned char* in, unsigned w, unsigned h, 238 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 239 unsigned encode(std::vector<unsigned char>& out, 240 const std::vector<unsigned char>& in, unsigned w, unsigned h, 241 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 242 #ifdef LODEPNG_COMPILE_DISK 243 /* 244 Converts 32-bit RGBA raw pixel data into a PNG file on disk. 245 Same as the other encode functions, but instead takes a filename as output. 246 NOTE: This overwrites existing files without warning! 247 */ 248 unsigned encode(const std::string& filename, 249 const unsigned char* in, unsigned w, unsigned h, 250 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 251 unsigned encode(const std::string& filename, 252 const std::vector<unsigned char>& in, unsigned w, unsigned h, 253 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 254 #endif /* LODEPNG_COMPILE_DISK */ 255 #endif /* LODEPNG_COMPILE_ENCODER */ 256 } /* namespace lodepng */ 257 #endif /*LODEPNG_COMPILE_CPP*/ 258 #endif /*LODEPNG_COMPILE_PNG*/ 259 260 #ifdef LODEPNG_COMPILE_ERROR_TEXT 261 /*Returns an English description of the numerical error code.*/ 262 const char* lodepng_error_text(unsigned code); 263 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/ 264 265 #ifdef LODEPNG_COMPILE_DECODER 266 /*Settings for zlib decompression*/ 267 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; 268 struct LodePNGDecompressSettings { 269 /* Check LodePNGDecoderSettings for more ignorable errors such as ignore_crc */ 270 unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ 271 unsigned ignore_nlen; /*ignore complement of len checksum in uncompressed blocks*/ 272 273 /*Maximum decompressed size, beyond this the decoder may (and is encouraged to) stop decoding, 274 return an error, output a data size > max_output_size and all the data up to that point. This is 275 not hard limit nor a guarantee, but can prevent excessive memory usage. This setting is 276 ignored by the PNG decoder, but is used by the deflate/zlib decoder and can be used by custom ones. 277 Set to 0 to impose no limit (the default).*/ 278 size_t max_output_size; 279 280 /*use custom zlib decoder instead of built in one (default: null). 281 Should return 0 if success, any non-0 if error (numeric value not exposed).*/ 282 unsigned (*custom_zlib)(unsigned char**, size_t*, 283 const unsigned char*, size_t, 284 const LodePNGDecompressSettings*); 285 /*use custom deflate decoder instead of built in one (default: null) 286 if custom_zlib is not null, custom_inflate is ignored (the zlib format uses deflate). 287 Should return 0 if success, any non-0 if error (numeric value not exposed).*/ 288 unsigned (*custom_inflate)(unsigned char**, size_t*, 289 const unsigned char*, size_t, 290 const LodePNGDecompressSettings*); 291 292 const void* custom_context; /*optional custom settings for custom functions*/ 293 }; 294 295 extern const LodePNGDecompressSettings lodepng_default_decompress_settings; 296 void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings); 297 #endif /*LODEPNG_COMPILE_DECODER*/ 298 299 #ifdef LODEPNG_COMPILE_ENCODER 300 /* 301 Settings for zlib compression. Tweaking these settings tweaks the balance 302 between speed and compression ratio. 303 */ 304 typedef struct LodePNGCompressSettings LodePNGCompressSettings; 305 struct LodePNGCompressSettings /*deflate = compress*/ { 306 /*LZ77 related settings*/ 307 unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/ 308 unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ 309 unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/ 310 unsigned minmatch; /*minimum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ 311 unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/ 312 unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ 313 314 /*use custom zlib encoder instead of built in one (default: null)*/ 315 unsigned (*custom_zlib)(unsigned char**, size_t*, 316 const unsigned char*, size_t, 317 const LodePNGCompressSettings*); 318 /*use custom deflate encoder instead of built in one (default: null) 319 if custom_zlib is used, custom_deflate is ignored since only the built in 320 zlib function will call custom_deflate*/ 321 unsigned (*custom_deflate)(unsigned char**, size_t*, 322 const unsigned char*, size_t, 323 const LodePNGCompressSettings*); 324 325 const void* custom_context; /*optional custom settings for custom functions*/ 326 }; 327 328 extern const LodePNGCompressSettings lodepng_default_compress_settings; 329 void lodepng_compress_settings_init(LodePNGCompressSettings* settings); 330 #endif /*LODEPNG_COMPILE_ENCODER*/ 331 332 #ifdef LODEPNG_COMPILE_PNG 333 /* 334 Color mode of an image. Contains all information required to decode the pixel 335 bits to RGBA colors. This information is the same as used in the PNG file 336 format, and is used both for PNG and raw image data in LodePNG. 337 */ 338 typedef struct LodePNGColorMode { 339 /*header (IHDR)*/ 340 LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/ 341 unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ 342 343 /* 344 palette (PLTE and tRNS) 345 346 Dynamically allocated with the colors of the palette, including alpha. 347 This field may not be allocated directly, use lodepng_color_mode_init first, 348 then lodepng_palette_add per color to correctly initialize it (to ensure size 349 of exactly 1024 bytes). 350 351 The alpha channels must be set as well, set them to 255 for opaque images. 352 353 When decoding, by default you can ignore this palette, since LodePNG already 354 fills the palette colors in the pixels of the raw RGBA output. 355 356 The palette is only supported for color type 3. 357 */ 358 unsigned char* palette; /*palette in RGBARGBA... order. Must be either 0, or when allocated must have 1024 bytes*/ 359 size_t palettesize; /*palette size in number of colors (amount of used bytes is 4 * palettesize)*/ 360 361 /* 362 transparent color key (tRNS) 363 364 This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit. 365 For grayscale PNGs, r, g and b will all 3 be set to the same. 366 367 When decoding, by default you can ignore this information, since LodePNG sets 368 pixels with this key to transparent already in the raw RGBA output. 369 370 The color key is only supported for color types 0 and 2. 371 */ 372 unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ 373 unsigned key_r; /*red/grayscale component of color key*/ 374 unsigned key_g; /*green component of color key*/ 375 unsigned key_b; /*blue component of color key*/ 376 } LodePNGColorMode; 377 378 /*init, cleanup and copy functions to use with this struct*/ 379 void lodepng_color_mode_init(LodePNGColorMode* info); 380 void lodepng_color_mode_cleanup(LodePNGColorMode* info); 381 /*return value is error code (0 means no error)*/ 382 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source); 383 /* Makes a temporary LodePNGColorMode that does not need cleanup (no palette) */ 384 LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth); 385 386 void lodepng_palette_clear(LodePNGColorMode* info); 387 /*add 1 color to the palette*/ 388 unsigned lodepng_palette_add(LodePNGColorMode* info, 389 unsigned char r, unsigned char g, unsigned char b, unsigned char a); 390 391 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ 392 unsigned lodepng_get_bpp(const LodePNGColorMode* info); 393 /*get the amount of color channels used, based on colortype in the struct. 394 If a palette is used, it counts as 1 channel.*/ 395 unsigned lodepng_get_channels(const LodePNGColorMode* info); 396 /*is it a grayscale type? (only colortype 0 or 4)*/ 397 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info); 398 /*has it got an alpha channel? (only colortype 2 or 6)*/ 399 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info); 400 /*has it got a palette? (only colortype 3)*/ 401 unsigned lodepng_is_palette_type(const LodePNGColorMode* info); 402 /*only returns true if there is a palette and there is a value in the palette with alpha < 255. 403 Loops through the palette to check this.*/ 404 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info); 405 /* 406 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image. 407 Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels). 408 Returns false if the image can only have opaque pixels. 409 In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values, 410 or if "key_defined" is true. 411 */ 412 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info); 413 /*Returns the byte size of a raw image buffer with given width, height and color mode*/ 414 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color); 415 416 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 417 /*The information of a Time chunk in PNG.*/ 418 typedef struct LodePNGTime { 419 unsigned year; /*2 bytes used (0-65535)*/ 420 unsigned month; /*1-12*/ 421 unsigned day; /*1-31*/ 422 unsigned hour; /*0-23*/ 423 unsigned minute; /*0-59*/ 424 unsigned second; /*0-60 (to allow for leap seconds)*/ 425 } LodePNGTime; 426 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 427 428 /*Information about the PNG image, except pixels, width and height.*/ 429 typedef struct LodePNGInfo { 430 /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ 431 unsigned compression_method;/*compression method of the original file. Always 0.*/ 432 unsigned filter_method; /*filter method of the original file*/ 433 unsigned interlace_method; /*interlace method of the original file: 0=none, 1=Adam7*/ 434 LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/ 435 436 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 437 /* 438 Suggested background color chunk (bKGD) 439 440 This uses the same color mode and bit depth as the PNG (except no alpha channel), 441 with values truncated to the bit depth in the unsigned integer. 442 443 For grayscale and palette PNGs, the value is stored in background_r. The values 444 in background_g and background_b are then unused. 445 446 So when decoding, you may get these in a different color mode than the one you requested 447 for the raw pixels. 448 449 When encoding with auto_convert, you must use the color model defined in info_png.color for 450 these values. The encoder normally ignores info_png.color when auto_convert is on, but will 451 use it to interpret these values (and convert copies of them to its chosen color model). 452 453 When encoding, avoid setting this to an expensive color, such as a non-gray value 454 when the image is gray, or the compression will be worse since it will be forced to 455 write the PNG with a more expensive color mode (when auto_convert is on). 456 457 The decoder does not use this background color to edit the color of pixels. This is a 458 completely optional metadata feature. 459 */ 460 unsigned background_defined; /*is a suggested background color given?*/ 461 unsigned background_r; /*red/gray/palette component of suggested background color*/ 462 unsigned background_g; /*green component of suggested background color*/ 463 unsigned background_b; /*blue component of suggested background color*/ 464 465 /* 466 Non-international text chunks (tEXt and zTXt) 467 468 The char** arrays each contain num strings. The actual messages are in 469 text_strings, while text_keys are keywords that give a short description what 470 the actual text represents, e.g. Title, Author, Description, or anything else. 471 472 All the string fields below including strings, keys, names and language tags are null terminated. 473 The PNG specification uses null characters for the keys, names and tags, and forbids null 474 characters to appear in the main text which is why we can use null termination everywhere here. 475 476 A keyword is minimum 1 character and maximum 79 characters long (plus the 477 additional null terminator). It's discouraged to use a single line length 478 longer than 79 characters for texts. 479 480 Don't allocate these text buffers yourself. Use the init/cleanup functions 481 correctly and use lodepng_add_text and lodepng_clear_text. 482 483 Standard text chunk keywords and strings are encoded using Latin-1. 484 */ 485 size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/ 486 char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/ 487 char** text_strings; /*the actual text*/ 488 489 /* 490 International text chunks (iTXt) 491 Similar to the non-international text chunks, but with additional strings 492 "langtags" and "transkeys", and the following text encodings are used: 493 keys: Latin-1, langtags: ASCII, transkeys and strings: UTF-8. 494 keys must be 1-79 characters (plus the additional null terminator), the other 495 strings are any length. 496 */ 497 size_t itext_num; /*the amount of international texts in this PNG*/ 498 char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ 499 char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/ 500 char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/ 501 char** itext_strings; /*the actual international text - UTF-8 string*/ 502 503 /*time chunk (tIME)*/ 504 unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ 505 LodePNGTime time; 506 507 /*phys chunk (pHYs)*/ 508 unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/ 509 unsigned phys_x; /*pixels per unit in x direction*/ 510 unsigned phys_y; /*pixels per unit in y direction*/ 511 unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ 512 513 /* 514 Color profile related chunks: gAMA, cHRM, sRGB, iCPP 515 516 LodePNG does not apply any color conversions on pixels in the encoder or decoder and does not interpret these color 517 profile values. It merely passes on the information. If you wish to use color profiles and convert colors, please 518 use these values with a color management library. 519 520 See the PNG, ICC and sRGB specifications for more information about the meaning of these values. 521 */ 522 523 /* gAMA chunk: optional, overridden by sRGB or iCCP if those are present. */ 524 unsigned gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */ 525 unsigned gama_gamma; /* Gamma exponent times 100000 */ 526 527 /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */ 528 unsigned chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */ 529 unsigned chrm_white_x; /* White Point x times 100000 */ 530 unsigned chrm_white_y; /* White Point y times 100000 */ 531 unsigned chrm_red_x; /* Red x times 100000 */ 532 unsigned chrm_red_y; /* Red y times 100000 */ 533 unsigned chrm_green_x; /* Green x times 100000 */ 534 unsigned chrm_green_y; /* Green y times 100000 */ 535 unsigned chrm_blue_x; /* Blue x times 100000 */ 536 unsigned chrm_blue_y; /* Blue y times 100000 */ 537 538 /* 539 sRGB chunk: optional. May not appear at the same time as iCCP. 540 If gAMA is also present gAMA must contain value 45455. 541 If cHRM is also present cHRM must contain respectively 31270,32900,64000,33000,30000,60000,15000,6000. 542 */ 543 unsigned srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */ 544 unsigned srgb_intent; /* Rendering intent: 0=perceptual, 1=rel. colorimetric, 2=saturation, 3=abs. colorimetric */ 545 546 /* 547 iCCP chunk: optional. May not appear at the same time as sRGB. 548 549 LodePNG does not parse or use the ICC profile (except its color space header field for an edge case), a 550 separate library to handle the ICC data (not included in LodePNG) format is needed to use it for color 551 management and conversions. 552 553 For encoding, if iCCP is present, gAMA and cHRM are recommended to be added as well with values that match the ICC 554 profile as closely as possible, if you wish to do this you should provide the correct values for gAMA and cHRM and 555 enable their '_defined' flags since LodePNG will not automatically compute them from the ICC profile. 556 557 For encoding, the ICC profile is required by the PNG specification to be an "RGB" profile for non-gray 558 PNG color types and a "GRAY" profile for gray PNG color types. If you disable auto_convert, you must ensure 559 the ICC profile type matches your requested color type, else the encoder gives an error. If auto_convert is 560 enabled (the default), and the ICC profile is not a good match for the pixel data, this will result in an encoder 561 error if the pixel data has non-gray pixels for a GRAY profile, or a silent less-optimal compression of the pixel 562 data if the pixels could be encoded as grayscale but the ICC profile is RGB. 563 564 To avoid this do not set an ICC profile in the image unless there is a good reason for it, and when doing so 565 make sure you compute it carefully to avoid the above problems. 566 */ 567 unsigned iccp_defined; /* Whether an iCCP chunk is present (0 = not present, 1 = present). */ 568 char* iccp_name; /* Null terminated string with profile name, 1-79 bytes */ 569 /* 570 The ICC profile in iccp_profile_size bytes. 571 Don't allocate this buffer yourself. Use the init/cleanup functions 572 correctly and use lodepng_set_icc and lodepng_clear_icc. 573 */ 574 unsigned char* iccp_profile; 575 unsigned iccp_profile_size; /* The size of iccp_profile in bytes */ 576 577 /* End of color profile related chunks */ 578 579 580 /* 581 unknown chunks: chunks not known by LodePNG, passed on byte for byte. 582 583 There are 3 buffers, one for each position in the PNG where unknown chunks can appear. 584 Each buffer contains all unknown chunks for that position consecutively. 585 The 3 positions are: 586 0: between IHDR and PLTE, 1: between PLTE and IDAT, 2: between IDAT and IEND. 587 588 For encoding, do not store critical chunks or known chunks that are enabled with a "_defined" flag 589 above in here, since the encoder will blindly follow this and could then encode an invalid PNG file 590 (such as one with two IHDR chunks or the disallowed combination of sRGB with iCCP). But do use 591 this if you wish to store an ancillary chunk that is not supported by LodePNG (such as sPLT or hIST), 592 or any non-standard PNG chunk. 593 594 Do not allocate or traverse this data yourself. Use the chunk traversing functions declared 595 later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct. 596 */ 597 unsigned char* unknown_chunks_data[3]; 598 size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ 599 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 600 } LodePNGInfo; 601 602 /*init, cleanup and copy functions to use with this struct*/ 603 void lodepng_info_init(LodePNGInfo* info); 604 void lodepng_info_cleanup(LodePNGInfo* info); 605 /*return value is error code (0 means no error)*/ 606 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source); 607 608 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 609 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/ 610 void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ 611 612 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag, 613 const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/ 614 void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ 615 616 /*replaces if exists*/ 617 unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size); 618 void lodepng_clear_icc(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ 619 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 620 621 /* 622 Converts raw buffer from one color type to another color type, based on 623 LodePNGColorMode structs to describe the input and output color type. 624 See the reference manual at the end of this header file to see which color conversions are supported. 625 return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported) 626 The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel 627 of the output color type (lodepng_get_bpp). 628 For < 8 bpp images, there should not be padding bits at the end of scanlines. 629 For 16-bit per channel colors, uses big endian format like PNG does. 630 Return value is LodePNG error code 631 */ 632 unsigned lodepng_convert(unsigned char* out, const unsigned char* in, 633 const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in, 634 unsigned w, unsigned h); 635 636 #ifdef LODEPNG_COMPILE_DECODER 637 /* 638 Settings for the decoder. This contains settings for the PNG and the Zlib 639 decoder, but not the Info settings from the Info structs. 640 */ 641 typedef struct LodePNGDecoderSettings { 642 LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ 643 644 /* Check LodePNGDecompressSettings for more ignorable errors such as ignore_adler32 */ 645 unsigned ignore_crc; /*ignore CRC checksums*/ 646 unsigned ignore_critical; /*ignore unknown critical chunks*/ 647 unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/ 648 /* TODO: make a system involving warnings with levels and a strict mode instead. Other potentially recoverable 649 errors: srgb rendering intent value, size of content of ancillary chunks, more than 79 characters for some 650 strings, placement/combination rules for ancillary chunks, crc of unknown chunks, allowed characters 651 in string keys, etc... */ 652 653 unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ 654 655 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 656 unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/ 657 658 /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/ 659 unsigned remember_unknown_chunks; 660 661 /* maximum size for decompressed text chunks. If a text chunk's text is larger than this, an error is returned, 662 unless reading text chunks is disabled or this limit is set higher or disabled. Set to 0 to allow any size. 663 By default it is a value that prevents unreasonably large strings from hogging memory. */ 664 size_t max_text_size; 665 666 /* maximum size for compressed ICC chunks. If the ICC profile is larger than this, an error will be returned. Set to 667 0 to allow any size. By default this is a value that prevents ICC profiles that would be much larger than any 668 legitimate profile could be to hog memory. */ 669 size_t max_icc_size; 670 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 671 } LodePNGDecoderSettings; 672 673 void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); 674 #endif /*LODEPNG_COMPILE_DECODER*/ 675 676 #ifdef LODEPNG_COMPILE_ENCODER 677 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ 678 typedef enum LodePNGFilterStrategy { 679 /*every filter at zero*/ 680 LFS_ZERO = 0, 681 /*every filter at 1, 2, 3 or 4 (paeth), unlike LFS_ZERO not a good choice, but for testing*/ 682 LFS_ONE = 1, 683 LFS_TWO = 2, 684 LFS_THREE = 3, 685 LFS_FOUR = 4, 686 /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/ 687 LFS_MINSUM, 688 /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending 689 on the image, this is better or worse than minsum.*/ 690 LFS_ENTROPY, 691 /* 692 Brute-force-search PNG filters by compressing each filter for each scanline. 693 Experimental, very slow, and only rarely gives better compression than MINSUM. 694 */ 695 LFS_BRUTE_FORCE, 696 /*use predefined_filters buffer: you specify the filter type for each scanline*/ 697 LFS_PREDEFINED 698 } LodePNGFilterStrategy; 699 700 /*Gives characteristics about the integer RGBA colors of the image (count, alpha channel usage, bit depth, ...), 701 which helps decide which color model to use for encoding. 702 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/ 703 typedef struct LodePNGColorStats { 704 unsigned colored; /*not grayscale*/ 705 unsigned key; /*image is not opaque and color key is possible instead of full alpha*/ 706 unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/ 707 unsigned short key_g; 708 unsigned short key_b; 709 unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/ 710 unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16 or allow_palette is disabled.*/ 711 unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order, only valid when numcolors is valid*/ 712 unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for grayscale only. 16 if 16-bit per channel required.*/ 713 size_t numpixels; 714 715 /*user settings for computing/using the stats*/ 716 unsigned allow_palette; /*default 1. if 0, disallow choosing palette colortype in auto_choose_color, and don't count numcolors*/ 717 unsigned allow_greyscale; /*default 1. if 0, choose RGB or RGBA even if the image only has gray colors*/ 718 } LodePNGColorStats; 719 720 void lodepng_color_stats_init(LodePNGColorStats* stats); 721 722 /*Get a LodePNGColorStats of the image. The stats must already have been inited. 723 Returns error code (e.g. alloc fail) or 0 if ok.*/ 724 unsigned lodepng_compute_color_stats(LodePNGColorStats* stats, 725 const unsigned char* image, unsigned w, unsigned h, 726 const LodePNGColorMode* mode_in); 727 728 /*Settings for the encoder.*/ 729 typedef struct LodePNGEncoderSettings { 730 LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ 731 732 unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/ 733 734 /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than 735 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to 736 completely follow the official PNG heuristic, filter_palette_zero must be true and 737 filter_strategy must be LFS_MINSUM*/ 738 unsigned filter_palette_zero; 739 /*Which filter strategy to use when not using zeroes due to filter_palette_zero. 740 Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/ 741 LodePNGFilterStrategy filter_strategy; 742 /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with 743 the same length as the amount of scanlines in the image, and each value must <= 5. You 744 have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero 745 must be set to 0 to ensure this is also used on palette or low bitdepth images.*/ 746 const unsigned char* predefined_filters; 747 748 /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). 749 If colortype is 3, PLTE is _always_ created.*/ 750 unsigned force_palette; 751 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 752 /*add LodePNG identifier and version as a text chunk, for debugging*/ 753 unsigned add_id; 754 /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ 755 unsigned text_compression; 756 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 757 } LodePNGEncoderSettings; 758 759 void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); 760 #endif /*LODEPNG_COMPILE_ENCODER*/ 761 762 763 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) 764 /*The settings, state and information for extended encoding and decoding.*/ 765 typedef struct LodePNGState { 766 #ifdef LODEPNG_COMPILE_DECODER 767 LodePNGDecoderSettings decoder; /*the decoding settings*/ 768 #endif /*LODEPNG_COMPILE_DECODER*/ 769 #ifdef LODEPNG_COMPILE_ENCODER 770 LodePNGEncoderSettings encoder; /*the encoding settings*/ 771 #endif /*LODEPNG_COMPILE_ENCODER*/ 772 LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ 773 LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/ 774 unsigned error; 775 } LodePNGState; 776 777 /*init, cleanup and copy functions to use with this struct*/ 778 void lodepng_state_init(LodePNGState* state); 779 void lodepng_state_cleanup(LodePNGState* state); 780 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source); 781 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */ 782 783 #ifdef LODEPNG_COMPILE_DECODER 784 /* 785 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and 786 getting much more information about the PNG image and color mode. 787 */ 788 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, 789 LodePNGState* state, 790 const unsigned char* in, size_t insize); 791 792 /* 793 Read the PNG header, but not the actual data. This returns only the information 794 that is in the IHDR chunk of the PNG, such as width, height and color type. The 795 information is placed in the info_png field of the LodePNGState. 796 */ 797 unsigned lodepng_inspect(unsigned* w, unsigned* h, 798 LodePNGState* state, 799 const unsigned char* in, size_t insize); 800 #endif /*LODEPNG_COMPILE_DECODER*/ 801 802 /* 803 Reads one metadata chunk (other than IHDR) of the PNG file and outputs what it 804 read in the state. Returns error code on failure. 805 Use lodepng_inspect first with a new state, then e.g. lodepng_chunk_find_const 806 to find the desired chunk type, and if non null use lodepng_inspect_chunk (with 807 chunk_pointer - start_of_file as pos). 808 Supports most metadata chunks from the PNG standard (gAMA, bKGD, tEXt, ...). 809 Ignores unsupported, unknown, non-metadata or IHDR chunks (without error). 810 Requirements: &in[pos] must point to start of a chunk, must use regular 811 lodepng_inspect first since format of most other chunks depends on IHDR, and if 812 there is a PLTE chunk, that one must be inspected before tRNS or bKGD. 813 */ 814 unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos, 815 const unsigned char* in, size_t insize); 816 817 #ifdef LODEPNG_COMPILE_ENCODER 818 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ 819 unsigned lodepng_encode(unsigned char** out, size_t* outsize, 820 const unsigned char* image, unsigned w, unsigned h, 821 LodePNGState* state); 822 #endif /*LODEPNG_COMPILE_ENCODER*/ 823 824 /* 825 The lodepng_chunk functions are normally not needed, except to traverse the 826 unknown chunks stored in the LodePNGInfo struct, or add new ones to it. 827 It also allows traversing the chunks of an encoded PNG file yourself. 828 829 The chunk pointer always points to the beginning of the chunk itself, that is 830 the first byte of the 4 length bytes. 831 832 In the PNG file format, chunks have the following format: 833 -4 bytes length: length of the data of the chunk in bytes (chunk itself is 12 bytes longer) 834 -4 bytes chunk type (ASCII a-z,A-Z only, see below) 835 -length bytes of data (may be 0 bytes if length was 0) 836 -4 bytes of CRC, computed on chunk name + data 837 838 The first chunk starts at the 8th byte of the PNG file, the entire rest of the file 839 exists out of concatenated chunks with the above format. 840 841 PNG standard chunk ASCII naming conventions: 842 -First byte: uppercase = critical, lowercase = ancillary 843 -Second byte: uppercase = public, lowercase = private 844 -Third byte: must be uppercase 845 -Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy 846 */ 847 848 /* 849 Gets the length of the data of the chunk. Total chunk length has 12 bytes more. 850 There must be at least 4 bytes to read from. If the result value is too large, 851 it may be corrupt data. 852 */ 853 unsigned lodepng_chunk_length(const unsigned char* chunk); 854 855 /*puts the 4-byte type in null terminated string*/ 856 void lodepng_chunk_type(char type[5], const unsigned char* chunk); 857 858 /*check if the type is the given type*/ 859 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type); 860 861 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ 862 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk); 863 864 /*0: public, 1: private (see PNG standard)*/ 865 unsigned char lodepng_chunk_private(const unsigned char* chunk); 866 867 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ 868 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk); 869 870 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/ 871 unsigned char* lodepng_chunk_data(unsigned char* chunk); 872 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk); 873 874 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ 875 unsigned lodepng_chunk_check_crc(const unsigned char* chunk); 876 877 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ 878 void lodepng_chunk_generate_crc(unsigned char* chunk); 879 880 /* 881 Iterate to next chunks, allows iterating through all chunks of the PNG file. 882 Input must be at the beginning of a chunk (result of a previous lodepng_chunk_next call, 883 or the 8th byte of a PNG file which always has the first chunk), or alternatively may 884 point to the first byte of the PNG file (which is not a chunk but the magic header, the 885 function will then skip over it and return the first real chunk). 886 Will output pointer to the start of the next chunk, or at or beyond end of the file if there 887 is no more chunk after this or possibly if the chunk is corrupt. 888 Start this process at the 8th byte of the PNG file. 889 In a non-corrupt PNG file, the last chunk should have name "IEND". 890 */ 891 unsigned char* lodepng_chunk_next(unsigned char* chunk, unsigned char* end); 892 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk, const unsigned char* end); 893 894 /*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/ 895 unsigned char* lodepng_chunk_find(unsigned char* chunk, unsigned char* end, const char type[5]); 896 const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]); 897 898 /* 899 Appends chunk to the data in out. The given chunk should already have its chunk header. 900 The out variable and outsize are updated to reflect the new reallocated buffer. 901 Returns error code (0 if it went ok) 902 */ 903 unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk); 904 905 /* 906 Appends new chunk to out. The chunk to append is given by giving its length, type 907 and data separately. The type is a 4-letter string. 908 The out variable and outsize are updated to reflect the new reallocated buffer. 909 Returne error code (0 if it went ok) 910 */ 911 unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length, 912 const char* type, const unsigned char* data); 913 914 915 /*Calculate CRC32 of buffer*/ 916 unsigned lodepng_crc32(const unsigned char* buf, size_t len); 917 #endif /*LODEPNG_COMPILE_PNG*/ 918 919 920 #ifdef LODEPNG_COMPILE_ZLIB 921 /* 922 This zlib part can be used independently to zlib compress and decompress a 923 buffer. It cannot be used to create gzip files however, and it only supports the 924 part of zlib that is required for PNG, it does not support dictionaries. 925 */ 926 927 #ifdef LODEPNG_COMPILE_DECODER 928 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/ 929 unsigned lodepng_inflate(unsigned char** out, size_t* outsize, 930 const unsigned char* in, size_t insize, 931 const LodePNGDecompressSettings* settings); 932 933 /* 934 Decompresses Zlib data. Reallocates the out buffer and appends the data. The 935 data must be according to the zlib specification. 936 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 937 buffer and *outsize its size in bytes. out must be freed by user after usage. 938 */ 939 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, 940 const unsigned char* in, size_t insize, 941 const LodePNGDecompressSettings* settings); 942 #endif /*LODEPNG_COMPILE_DECODER*/ 943 944 #ifdef LODEPNG_COMPILE_ENCODER 945 /* 946 Compresses data with Zlib. Reallocates the out buffer and appends the data. 947 Zlib adds a small header and trailer around the deflate data. 948 The data is output in the format of the zlib specification. 949 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 950 buffer and *outsize its size in bytes. out must be freed by user after usage. 951 */ 952 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, 953 const unsigned char* in, size_t insize, 954 const LodePNGCompressSettings* settings); 955 956 /* 957 Find length-limited Huffman code for given frequencies. This function is in the 958 public interface only for tests, it's used internally by lodepng_deflate. 959 */ 960 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies, 961 size_t numcodes, unsigned maxbitlen); 962 963 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ 964 unsigned lodepng_deflate(unsigned char** out, size_t* outsize, 965 const unsigned char* in, size_t insize, 966 const LodePNGCompressSettings* settings); 967 968 #endif /*LODEPNG_COMPILE_ENCODER*/ 969 #endif /*LODEPNG_COMPILE_ZLIB*/ 970 971 #ifdef LODEPNG_COMPILE_DISK 972 /* 973 Load a file from disk into buffer. The function allocates the out buffer, and 974 after usage you should free it. 975 out: output parameter, contains pointer to loaded buffer. 976 outsize: output parameter, size of the allocated out buffer 977 filename: the path to the file to load 978 return value: error code (0 means ok) 979 */ 980 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename); 981 982 /* 983 Save a file from buffer to disk. Warning, if it exists, this function overwrites 984 the file without warning! 985 buffer: the buffer to write 986 buffersize: size of the buffer to write 987 filename: the path to the file to save to 988 return value: error code (0 means ok) 989 */ 990 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename); 991 #endif /*LODEPNG_COMPILE_DISK*/ 992 993 #ifdef LODEPNG_COMPILE_CPP 994 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */ 995 namespace lodepng { 996 #ifdef LODEPNG_COMPILE_PNG 997 class State : public LodePNGState { 998 public: 999 State(); 1000 State(const State& other); 1001 ~State(); 1002 State& operator=(const State& other); 1003 }; 1004 1005 #ifdef LODEPNG_COMPILE_DECODER 1006 /* Same as other lodepng::decode, but using a State for more settings and information. */ 1007 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 1008 State& state, 1009 const unsigned char* in, size_t insize); 1010 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 1011 State& state, 1012 const std::vector<unsigned char>& in); 1013 #endif /*LODEPNG_COMPILE_DECODER*/ 1014 1015 #ifdef LODEPNG_COMPILE_ENCODER 1016 /* Same as other lodepng::encode, but using a State for more settings and information. */ 1017 unsigned encode(std::vector<unsigned char>& out, 1018 const unsigned char* in, unsigned w, unsigned h, 1019 State& state); 1020 unsigned encode(std::vector<unsigned char>& out, 1021 const std::vector<unsigned char>& in, unsigned w, unsigned h, 1022 State& state); 1023 #endif /*LODEPNG_COMPILE_ENCODER*/ 1024 1025 #ifdef LODEPNG_COMPILE_DISK 1026 /* 1027 Load a file from disk into an std::vector. 1028 return value: error code (0 means ok) 1029 */ 1030 unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename); 1031 1032 /* 1033 Save the binary data in an std::vector to a file on disk. The file is overwritten 1034 without warning. 1035 */ 1036 unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename); 1037 #endif /* LODEPNG_COMPILE_DISK */ 1038 #endif /* LODEPNG_COMPILE_PNG */ 1039 1040 #ifdef LODEPNG_COMPILE_ZLIB 1041 #ifdef LODEPNG_COMPILE_DECODER 1042 /* Zlib-decompress an unsigned char buffer */ 1043 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 1044 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 1045 1046 /* Zlib-decompress an std::vector */ 1047 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 1048 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 1049 #endif /* LODEPNG_COMPILE_DECODER */ 1050 1051 #ifdef LODEPNG_COMPILE_ENCODER 1052 /* Zlib-compress an unsigned char buffer */ 1053 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 1054 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 1055 1056 /* Zlib-compress an std::vector */ 1057 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 1058 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 1059 #endif /* LODEPNG_COMPILE_ENCODER */ 1060 #endif /* LODEPNG_COMPILE_ZLIB */ 1061 } /* namespace lodepng */ 1062 #endif /*LODEPNG_COMPILE_CPP*/ 1063 1064 /* 1065 TODO: 1066 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often 1067 [.] check compatibility with various compilers - done but needs to be redone for every newer version 1068 [X] converting color to 16-bit per channel types 1069 [X] support color profile chunk types (but never let them touch RGB values by default) 1070 [ ] support all public PNG chunk types (almost done except sBIT, sPLT and hIST) 1071 [ ] make sure encoder generates no chunks with size > (2^31)-1 1072 [ ] partial decoding (stream processing) 1073 [X] let the "isFullyOpaque" function check color keys and transparent palettes too 1074 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl" 1075 [ ] allow treating some errors like warnings, when image is recoverable (e.g. 69, 57, 58) 1076 [ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ... 1077 [ ] error messages with line numbers (and version) 1078 [ ] errors in state instead of as return code? 1079 [ ] new errors/warnings like suspiciously big decompressed ztxt or iccp chunk 1080 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes 1081 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ... 1082 [ ] allow user to give data (void*) to custom allocator 1083 [X] provide alternatives for C library functions not present on some platforms (memcpy, ...) 1084 */ 1085 1086 #endif /*LODEPNG_H inclusion guard*/ 1087 1088 /* 1089 LodePNG Documentation 1090 --------------------- 1091 1092 0. table of contents 1093 -------------------- 1094 1095 1. about 1096 1.1. supported features 1097 1.2. features not supported 1098 2. C and C++ version 1099 3. security 1100 4. decoding 1101 5. encoding 1102 6. color conversions 1103 6.1. PNG color types 1104 6.2. color conversions 1105 6.3. padding bits 1106 6.4. A note about 16-bits per channel and endianness 1107 7. error values 1108 8. chunks and PNG editing 1109 9. compiler support 1110 10. examples 1111 10.1. decoder C++ example 1112 10.2. decoder C example 1113 11. state settings reference 1114 12. changes 1115 13. contact information 1116 1117 1118 1. about 1119 -------- 1120 1121 PNG is a file format to store raster images losslessly with good compression, 1122 supporting different color types and alpha channel. 1123 1124 LodePNG is a PNG codec according to the Portable Network Graphics (PNG) 1125 Specification (Second Edition) - W3C Recommendation 10 November 2003. 1126 1127 The specifications used are: 1128 1129 *) Portable Network Graphics (PNG) Specification (Second Edition): 1130 http://www.w3.org/TR/2003/REC-PNG-20031110 1131 *) RFC 1950 ZLIB Compressed Data Format version 3.3: 1132 http://www.gzip.org/zlib/rfc-zlib.html 1133 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3: 1134 http://www.gzip.org/zlib/rfc-deflate.html 1135 1136 The most recent version of LodePNG can currently be found at 1137 http://lodev.org/lodepng/ 1138 1139 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds 1140 extra functionality. 1141 1142 LodePNG exists out of two files: 1143 -lodepng.h: the header file for both C and C++ 1144 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage 1145 1146 If you want to start using LodePNG right away without reading this doc, get the 1147 examples from the LodePNG website to see how to use it in code, or check the 1148 smaller examples in chapter 13 here. 1149 1150 LodePNG is simple but only supports the basic requirements. To achieve 1151 simplicity, the following design choices were made: There are no dependencies 1152 on any external library. There are functions to decode and encode a PNG with 1153 a single function call, and extended versions of these functions taking a 1154 LodePNGState struct allowing to specify or get more information. By default 1155 the colors of the raw image are always RGB or RGBA, no matter what color type 1156 the PNG file uses. To read and write files, there are simple functions to 1157 convert the files to/from buffers in memory. 1158 1159 This all makes LodePNG suitable for loading textures in games, demos and small 1160 programs, ... It's less suitable for full fledged image editors, loading PNGs 1161 over network (it requires all the image data to be available before decoding can 1162 begin), life-critical systems, ... 1163 1164 1.1. supported features 1165 ----------------------- 1166 1167 The following features are supported by the decoder: 1168 1169 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image, 1170 or the same color type as the PNG 1171 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image 1172 *) Adam7 interlace and deinterlace for any color type 1173 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk 1174 *) support for alpha channels, including RGBA color model, translucent palettes and color keying 1175 *) zlib decompression (inflate) 1176 *) zlib compression (deflate) 1177 *) CRC32 and ADLER32 checksums 1178 *) colorimetric color profile conversions: currently experimentally available in lodepng_util.cpp only, 1179 plus alternatively ability to pass on chroma/gamma/ICC profile information to other color management system. 1180 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks. 1181 *) the following chunks are supported by both encoder and decoder: 1182 IHDR: header information 1183 PLTE: color palette 1184 IDAT: pixel data 1185 IEND: the final chunk 1186 tRNS: transparency for palettized images 1187 tEXt: textual information 1188 zTXt: compressed textual information 1189 iTXt: international textual information 1190 bKGD: suggested background color 1191 pHYs: physical dimensions 1192 tIME: modification time 1193 cHRM: RGB chromaticities 1194 gAMA: RGB gamma correction 1195 iCCP: ICC color profile 1196 sRGB: rendering intent 1197 1198 1.2. features not supported 1199 --------------------------- 1200 1201 The following features are _not_ supported: 1202 1203 *) some features needed to make a conformant PNG-Editor might be still missing. 1204 *) partial loading/stream processing. All data must be available and is processed in one call. 1205 *) The following public chunks are not (yet) supported but treated as unknown chunks by LodePNG: 1206 sBIT 1207 hIST 1208 sPLT 1209 1210 1211 2. C and C++ version 1212 -------------------- 1213 1214 The C version uses buffers allocated with alloc that you need to free() 1215 yourself. You need to use init and cleanup functions for each struct whenever 1216 using a struct from the C version to avoid exploits and memory leaks. 1217 1218 The C++ version has extra functions with std::vectors in the interface and the 1219 lodepng::State class which is a LodePNGState with constructor and destructor. 1220 1221 These files work without modification for both C and C++ compilers because all 1222 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers 1223 ignore it, and the C code is made to compile both with strict ISO C90 and C++. 1224 1225 To use the C++ version, you need to rename the source file to lodepng.cpp 1226 (instead of lodepng.c), and compile it with a C++ compiler. 1227 1228 To use the C version, you need to rename the source file to lodepng.c (instead 1229 of lodepng.cpp), and compile it with a C compiler. 1230 1231 1232 3. Security 1233 ----------- 1234 1235 Even if carefully designed, it's always possible that LodePNG contains possible 1236 exploits. If you discover one, please let me know, and it will be fixed. 1237 1238 When using LodePNG, care has to be taken with the C version of LodePNG, as well 1239 as the C-style structs when working with C++. The following conventions are used 1240 for all C-style structs: 1241 1242 -if a struct has a corresponding init function, always call the init function when making a new one 1243 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks 1244 -if a struct has a corresponding copy function, use the copy function instead of "=". 1245 The destination must also be inited already. 1246 1247 1248 4. Decoding 1249 ----------- 1250 1251 Decoding converts a PNG compressed image to a raw pixel buffer. 1252 1253 Most documentation on using the decoder is at its declarations in the header 1254 above. For C, simple decoding can be done with functions such as 1255 lodepng_decode32, and more advanced decoding can be done with the struct 1256 LodePNGState and lodepng_decode. For C++, all decoding can be done with the 1257 various lodepng::decode functions, and lodepng::State can be used for advanced 1258 features. 1259 1260 When using the LodePNGState, it uses the following fields for decoding: 1261 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here 1262 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get 1263 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use 1264 1265 LodePNGInfo info_png 1266 -------------------- 1267 1268 After decoding, this contains extra information of the PNG image, except the actual 1269 pixels, width and height because these are already gotten directly from the decoder 1270 functions. 1271 1272 It contains for example the original color type of the PNG image, text comments, 1273 suggested background color, etc... More details about the LodePNGInfo struct are 1274 at its declaration documentation. 1275 1276 LodePNGColorMode info_raw 1277 ------------------------- 1278 1279 When decoding, here you can specify which color type you want 1280 the resulting raw image to be. If this is different from the colortype of the 1281 PNG, then the decoder will automatically convert the result. This conversion 1282 always works, except if you want it to convert a color PNG to grayscale or to 1283 a palette with missing colors. 1284 1285 By default, 32-bit color is used for the result. 1286 1287 LodePNGDecoderSettings decoder 1288 ------------------------------ 1289 1290 The settings can be used to ignore the errors created by invalid CRC and Adler32 1291 chunks, and to disable the decoding of tEXt chunks. 1292 1293 There's also a setting color_convert, true by default. If false, no conversion 1294 is done, the resulting data will be as it was in the PNG (after decompression) 1295 and you'll have to puzzle the colors of the pixels together yourself using the 1296 color type information in the LodePNGInfo. 1297 1298 1299 5. Encoding 1300 ----------- 1301 1302 Encoding converts a raw pixel buffer to a PNG compressed image. 1303 1304 Most documentation on using the encoder is at its declarations in the header 1305 above. For C, simple encoding can be done with functions such as 1306 lodepng_encode32, and more advanced decoding can be done with the struct 1307 LodePNGState and lodepng_encode. For C++, all encoding can be done with the 1308 various lodepng::encode functions, and lodepng::State can be used for advanced 1309 features. 1310 1311 Like the decoder, the encoder can also give errors. However it gives less errors 1312 since the encoder input is trusted, the decoder input (a PNG image that could 1313 be forged by anyone) is not trusted. 1314 1315 When using the LodePNGState, it uses the following fields for encoding: 1316 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be. 1317 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has 1318 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use 1319 1320 LodePNGInfo info_png 1321 -------------------- 1322 1323 When encoding, you use this the opposite way as when decoding: for encoding, 1324 you fill in the values you want the PNG to have before encoding. By default it's 1325 not needed to specify a color type for the PNG since it's automatically chosen, 1326 but it's possible to choose it yourself given the right settings. 1327 1328 The encoder will not always exactly match the LodePNGInfo struct you give, 1329 it tries as close as possible. Some things are ignored by the encoder. The 1330 encoder uses, for example, the following settings from it when applicable: 1331 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the 1332 background color, the interlace method, unknown chunks, ... 1333 1334 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk. 1335 If the palette contains any colors for which the alpha channel is not 255 (so 1336 there are translucent colors in the palette), it'll add a tRNS chunk. 1337 1338 LodePNGColorMode info_raw 1339 ------------------------- 1340 1341 You specify the color type of the raw image that you give to the input here, 1342 including a possible transparent color key and palette you happen to be using in 1343 your raw image data. 1344 1345 By default, 32-bit color is assumed, meaning your input has to be in RGBA 1346 format with 4 bytes (unsigned chars) per pixel. 1347 1348 LodePNGEncoderSettings encoder 1349 ------------------------------ 1350 1351 The following settings are supported (some are in sub-structs): 1352 *) auto_convert: when this option is enabled, the encoder will 1353 automatically choose the smallest possible color mode (including color key) that 1354 can encode the colors of all pixels without information loss. 1355 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree, 1356 2 = dynamic huffman tree (best compression). Should be 2 for proper 1357 compression. 1358 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be 1359 true for proper compression. 1360 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value 1361 2048 by default, but can be set to 32768 for better, but slow, compression. 1362 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE 1363 chunk if force_palette is true. This can used as suggested palette to convert 1364 to by viewers that don't support more than 256 colors (if those still exist) 1365 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image. 1366 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks. 1367 zTXt chunks use zlib compression on the text. This gives a smaller result on 1368 large texts but a larger result on small texts (such as a single program name). 1369 It's all tEXt or all zTXt though, there's no separate setting per text yet. 1370 1371 1372 6. color conversions 1373 -------------------- 1374 1375 An important thing to note about LodePNG, is that the color type of the PNG, and 1376 the color type of the raw image, are completely independent. By default, when 1377 you decode a PNG, you get the result as a raw image in the color type you want, 1378 no matter whether the PNG was encoded with a palette, grayscale or RGBA color. 1379 And if you encode an image, by default LodePNG will automatically choose the PNG 1380 color type that gives good compression based on the values of colors and amount 1381 of colors in the image. It can be configured to let you control it instead as 1382 well, though. 1383 1384 To be able to do this, LodePNG does conversions from one color mode to another. 1385 It can convert from almost any color type to any other color type, except the 1386 following conversions: RGB to grayscale is not supported, and converting to a 1387 palette when the palette doesn't have a required color is not supported. This is 1388 not supported on purpose: this is information loss which requires a color 1389 reduction algorithm that is beyond the scope of a PNG encoder (yes, RGB to gray 1390 is easy, but there are multiple ways if you want to give some channels more 1391 weight). 1392 1393 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB 1394 color, no matter what color type the PNG has. And by default when encoding, 1395 LodePNG automatically picks the best color model for the output PNG, and expects 1396 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control 1397 the color format of the images yourself, you can skip this chapter. 1398 1399 6.1. PNG color types 1400 -------------------- 1401 1402 A PNG image can have many color types, ranging from 1-bit color to 64-bit color, 1403 as well as palettized color modes. After the zlib decompression and unfiltering 1404 in the PNG image is done, the raw pixel data will have that color type and thus 1405 a certain amount of bits per pixel. If you want the output raw image after 1406 decoding to have another color type, a conversion is done by LodePNG. 1407 1408 The PNG specification gives the following color types: 1409 1410 0: grayscale, bit depths 1, 2, 4, 8, 16 1411 2: RGB, bit depths 8 and 16 1412 3: palette, bit depths 1, 2, 4 and 8 1413 4: grayscale with alpha, bit depths 8 and 16 1414 6: RGBA, bit depths 8 and 16 1415 1416 Bit depth is the amount of bits per pixel per color channel. So the total amount 1417 of bits per pixel is: amount of channels * bitdepth. 1418 1419 6.2. color conversions 1420 ---------------------- 1421 1422 As explained in the sections about the encoder and decoder, you can specify 1423 color types and bit depths in info_png and info_raw to change the default 1424 behaviour. 1425 1426 If, when decoding, you want the raw image to be something else than the default, 1427 you need to set the color type and bit depth you want in the LodePNGColorMode, 1428 or the parameters colortype and bitdepth of the simple decoding function. 1429 1430 If, when encoding, you use another color type than the default in the raw input 1431 image, you need to specify its color type and bit depth in the LodePNGColorMode 1432 of the raw image, or use the parameters colortype and bitdepth of the simple 1433 encoding function. 1434 1435 If, when encoding, you don't want LodePNG to choose the output PNG color type 1436 but control it yourself, you need to set auto_convert in the encoder settings 1437 to false, and specify the color type you want in the LodePNGInfo of the 1438 encoder (including palette: it can generate a palette if auto_convert is true, 1439 otherwise not). 1440 1441 If the input and output color type differ (whether user chosen or auto chosen), 1442 LodePNG will do a color conversion, which follows the rules below, and may 1443 sometimes result in an error. 1444 1445 To avoid some confusion: 1446 -the decoder converts from PNG to raw image 1447 -the encoder converts from raw image to PNG 1448 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image 1449 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG 1450 -when encoding, the color type in LodePNGInfo is ignored if auto_convert 1451 is enabled, it is automatically generated instead 1452 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original 1453 PNG image, but it can be ignored since the raw image has the color type you requested instead 1454 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion 1455 between the color types is done if the color types are supported. If it is not 1456 supported, an error is returned. If the types are the same, no conversion is done. 1457 -even though some conversions aren't supported, LodePNG supports loading PNGs from any 1458 colortype and saving PNGs to any colortype, sometimes it just requires preparing 1459 the raw image correctly before encoding. 1460 -both encoder and decoder use the same color converter. 1461 1462 The function lodepng_convert does the color conversion. It is available in the 1463 interface but normally isn't needed since the encoder and decoder already call 1464 it. 1465 1466 Non supported color conversions: 1467 -color to grayscale when non-gray pixels are present: no error is thrown, but 1468 the result will look ugly because only the red channel is taken (it assumes all 1469 three channels are the same in this case so ignores green and blue). The reason 1470 no error is given is to allow converting from three-channel grayscale images to 1471 one-channel even if there are numerical imprecisions. 1472 -anything to palette when the palette does not have an exact match for a from-color 1473 in it: in this case an error is thrown 1474 1475 Supported color conversions: 1476 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA 1477 -any gray or gray+alpha, to gray or gray+alpha 1478 -anything to a palette, as long as the palette has the requested colors in it 1479 -removing alpha channel 1480 -higher to smaller bitdepth, and vice versa 1481 1482 If you want no color conversion to be done (e.g. for speed or control): 1483 -In the encoder, you can make it save a PNG with any color type by giving the 1484 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to 1485 false. 1486 -In the decoder, you can make it store the pixel data in the same color type 1487 as the PNG has, by setting the color_convert setting to false. Settings in 1488 info_raw are then ignored. 1489 1490 6.3. padding bits 1491 ----------------- 1492 1493 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines 1494 have a bit amount that isn't a multiple of 8, then padding bits are used so that each 1495 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output. 1496 The raw input image you give to the encoder, and the raw output image you get from the decoder 1497 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width 1498 of 7 pixels, the first pixel of the second scanline will the 8th bit of the first byte, 1499 not the first bit of a new byte. 1500 1501 6.4. A note about 16-bits per channel and endianness 1502 ---------------------------------------------------- 1503 1504 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like 1505 for any other color format. The 16-bit values are stored in big endian (most 1506 significant byte first) in these arrays. This is the opposite order of the 1507 little endian used by x86 CPU's. 1508 1509 LodePNG always uses big endian because the PNG file format does so internally. 1510 Conversions to other formats than PNG uses internally are not supported by 1511 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit 1512 colors, the order in which you store R, G, B and A, and so on. Supporting and 1513 converting to/from all that is outside the scope of LodePNG. 1514 1515 This may mean that, depending on your use case, you may want to convert the big 1516 endian output of LodePNG to little endian with a for loop. This is certainly not 1517 always needed, many applications and libraries support big endian 16-bit colors 1518 anyway, but it means you cannot simply cast the unsigned char* buffer to an 1519 unsigned short* buffer on x86 CPUs. 1520 1521 1522 7. error values 1523 --------------- 1524 1525 All functions in LodePNG that return an error code, return 0 if everything went 1526 OK, or a non-zero code if there was an error. 1527 1528 The meaning of the LodePNG error values can be retrieved with the function 1529 lodepng_error_text: given the numerical error code, it returns a description 1530 of the error in English as a string. 1531 1532 Check the implementation of lodepng_error_text to see the meaning of each code. 1533 1534 It is not recommended to use the numerical values to programmatically make 1535 different decisions based on error types as the numbers are not guaranteed to 1536 stay backwards compatible. They are for human consumption only. Programmatically 1537 only 0 or non-0 matter. 1538 1539 1540 8. chunks and PNG editing 1541 ------------------------- 1542 1543 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG 1544 editor that should follow the rules about handling of unknown chunks, or if your 1545 program is able to read other types of chunks than the ones handled by LodePNG, 1546 then that's possible with the chunk functions of LodePNG. 1547 1548 A PNG chunk has the following layout: 1549 1550 4 bytes length 1551 4 bytes type name 1552 length bytes data 1553 4 bytes CRC 1554 1555 8.1. iterating through chunks 1556 ----------------------------- 1557 1558 If you have a buffer containing the PNG image data, then the first chunk (the 1559 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the 1560 signature of the PNG and are not part of a chunk. But if you start at byte 8 1561 then you have a chunk, and can check the following things of it. 1562 1563 NOTE: none of these functions check for memory buffer boundaries. To avoid 1564 exploits, always make sure the buffer contains all the data of the chunks. 1565 When using lodepng_chunk_next, make sure the returned value is within the 1566 allocated memory. 1567 1568 unsigned lodepng_chunk_length(const unsigned char* chunk): 1569 1570 Get the length of the chunk's data. The total chunk length is this length + 12. 1571 1572 void lodepng_chunk_type(char type[5], const unsigned char* chunk): 1573 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type): 1574 1575 Get the type of the chunk or compare if it's a certain type 1576 1577 unsigned char lodepng_chunk_critical(const unsigned char* chunk): 1578 unsigned char lodepng_chunk_private(const unsigned char* chunk): 1579 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk): 1580 1581 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are). 1582 Check if the chunk is private (public chunks are part of the standard, private ones not). 1583 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical 1584 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your 1585 program doesn't handle that type of unknown chunk. 1586 1587 unsigned char* lodepng_chunk_data(unsigned char* chunk): 1588 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk): 1589 1590 Get a pointer to the start of the data of the chunk. 1591 1592 unsigned lodepng_chunk_check_crc(const unsigned char* chunk): 1593 void lodepng_chunk_generate_crc(unsigned char* chunk): 1594 1595 Check if the crc is correct or generate a correct one. 1596 1597 unsigned char* lodepng_chunk_next(unsigned char* chunk): 1598 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk): 1599 1600 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these 1601 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough 1602 data available in the buffer to be able to go to the next chunk. 1603 1604 unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk): 1605 unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length, 1606 const char* type, const unsigned char* data): 1607 1608 These functions are used to create new chunks that are appended to the data in *out that has 1609 length *outsize. The append function appends an existing chunk to the new data. The create 1610 function creates a new chunk with the given parameters and appends it. Type is the 4-letter 1611 name of the chunk. 1612 1613 8.2. chunks in info_png 1614 ----------------------- 1615 1616 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3 1617 buffers (each with size) to contain 3 types of unknown chunks: 1618 the ones that come before the PLTE chunk, the ones that come between the PLTE 1619 and the IDAT chunks, and the ones that come after the IDAT chunks. 1620 It's necessary to make the distinction between these 3 cases because the PNG 1621 standard forces to keep the ordering of unknown chunks compared to the critical 1622 chunks, but does not force any other ordering rules. 1623 1624 info_png.unknown_chunks_data[0] is the chunks before PLTE 1625 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT 1626 info_png.unknown_chunks_data[2] is the chunks after IDAT 1627 1628 The chunks in these 3 buffers can be iterated through and read by using the same 1629 way described in the previous subchapter. 1630 1631 When using the decoder to decode a PNG, you can make it store all unknown chunks 1632 if you set the option settings.remember_unknown_chunks to 1. By default, this 1633 option is off (0). 1634 1635 The encoder will always encode unknown chunks that are stored in the info_png. 1636 If you need it to add a particular chunk that isn't known by LodePNG, you can 1637 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in 1638 info_png.unknown_chunks_data[x]. 1639 1640 Chunks that are known by LodePNG should not be added in that way. E.g. to make 1641 LodePNG add a bKGD chunk, set background_defined to true and add the correct 1642 parameters there instead. 1643 1644 1645 9. compiler support 1646 ------------------- 1647 1648 No libraries other than the current standard C library are needed to compile 1649 LodePNG. For the C++ version, only the standard C++ library is needed on top. 1650 Add the files lodepng.c(pp) and lodepng.h to your project, include 1651 lodepng.h where needed, and your program can read/write PNG files. 1652 1653 It is compatible with C90 and up, and C++03 and up. 1654 1655 If performance is important, use optimization when compiling! For both the 1656 encoder and decoder, this makes a large difference. 1657 1658 Make sure that LodePNG is compiled with the same compiler of the same version 1659 and with the same settings as the rest of the program, or the interfaces with 1660 std::vectors and std::strings in C++ can be incompatible. 1661 1662 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets. 1663 1664 *) gcc and g++ 1665 1666 LodePNG is developed in gcc so this compiler is natively supported. It gives no 1667 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++ 1668 version 4.7.1 on Linux, 32-bit and 64-bit. 1669 1670 *) Clang 1671 1672 Fully supported and warning-free. 1673 1674 *) Mingw 1675 1676 The Mingw compiler (a port of gcc for Windows) should be fully supported by 1677 LodePNG. 1678 1679 *) Visual Studio and Visual C++ Express Edition 1680 1681 LodePNG should be warning-free with warning level W4. Two warnings were disabled 1682 with pragmas though: warning 4244 about implicit conversions, and warning 4996 1683 where it wants to use a non-standard function fopen_s instead of the standard C 1684 fopen. 1685 1686 Visual Studio may want "stdafx.h" files to be included in each source file and 1687 give an error "unexpected end of file while looking for precompiled header". 1688 This is not standard C++ and will not be added to the stock LodePNG. You can 1689 disable it for lodepng.cpp only by right clicking it, Properties, C/C++, 1690 Precompiled Headers, and set it to Not Using Precompiled Headers there. 1691 1692 NOTE: Modern versions of VS should be fully supported, but old versions, e.g. 1693 VS6, are not guaranteed to work. 1694 1695 *) Compilers on Macintosh 1696 1697 LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for 1698 C and C++. 1699 1700 *) Other Compilers 1701 1702 If you encounter problems on any compilers, feel free to let me know and I may 1703 try to fix it if the compiler is modern and standards compliant. 1704 1705 1706 10. examples 1707 ------------ 1708 1709 This decoder example shows the most basic usage of LodePNG. More complex 1710 examples can be found on the LodePNG website. 1711 1712 10.1. decoder C++ example 1713 ------------------------- 1714 1715 #include "lodepng.h" 1716 #include <iostream> 1717 1718 int main(int argc, char *argv[]) { 1719 const char* filename = argc > 1 ? argv[1] : "test.png"; 1720 1721 //load and decode 1722 std::vector<unsigned char> image; 1723 unsigned width, height; 1724 unsigned error = lodepng::decode(image, width, height, filename); 1725 1726 //if there's an error, display it 1727 if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl; 1728 1729 //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ... 1730 } 1731 1732 10.2. decoder C example 1733 ----------------------- 1734 1735 #include "lodepng.h" 1736 1737 int main(int argc, char *argv[]) { 1738 unsigned error; 1739 unsigned char* image; 1740 size_t width, height; 1741 const char* filename = argc > 1 ? argv[1] : "test.png"; 1742 1743 error = lodepng_decode32_file(&image, &width, &height, filename); 1744 1745 if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error)); 1746 1747 / * use image here * / 1748 1749 free(image); 1750 return 0; 1751 } 1752 1753 11. state settings reference 1754 ---------------------------- 1755 1756 A quick reference of some settings to set on the LodePNGState 1757 1758 For decoding: 1759 1760 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums 1761 state.decoder.zlibsettings.custom_...: use custom inflate function 1762 state.decoder.ignore_crc: ignore CRC checksums 1763 state.decoder.ignore_critical: ignore unknown critical chunks 1764 state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors 1765 state.decoder.color_convert: convert internal PNG color to chosen one 1766 state.decoder.read_text_chunks: whether to read in text metadata chunks 1767 state.decoder.remember_unknown_chunks: whether to read in unknown chunks 1768 state.info_raw.colortype: desired color type for decoded image 1769 state.info_raw.bitdepth: desired bit depth for decoded image 1770 state.info_raw....: more color settings, see struct LodePNGColorMode 1771 state.info_png....: no settings for decoder but ouput, see struct LodePNGInfo 1772 1773 For encoding: 1774 1775 state.encoder.zlibsettings.btype: disable compression by setting it to 0 1776 state.encoder.zlibsettings.use_lz77: use LZ77 in compression 1777 state.encoder.zlibsettings.windowsize: tweak LZ77 windowsize 1778 state.encoder.zlibsettings.minmatch: tweak min LZ77 length to match 1779 state.encoder.zlibsettings.nicematch: tweak LZ77 match where to stop searching 1780 state.encoder.zlibsettings.lazymatching: try one more LZ77 matching 1781 state.encoder.zlibsettings.custom_...: use custom deflate function 1782 state.encoder.auto_convert: choose optimal PNG color type, if 0 uses info_png 1783 state.encoder.filter_palette_zero: PNG filter strategy for palette 1784 state.encoder.filter_strategy: PNG filter strategy to encode with 1785 state.encoder.force_palette: add palette even if not encoding to one 1786 state.encoder.add_id: add LodePNG identifier and version as a text chunk 1787 state.encoder.text_compression: use compressed text chunks for metadata 1788 state.info_raw.colortype: color type of raw input image you provide 1789 state.info_raw.bitdepth: bit depth of raw input image you provide 1790 state.info_raw: more color settings, see struct LodePNGColorMode 1791 state.info_png.color.colortype: desired color type if auto_convert is false 1792 state.info_png.color.bitdepth: desired bit depth if auto_convert is false 1793 state.info_png.color....: more color settings, see struct LodePNGColorMode 1794 state.info_png....: more PNG related settings, see struct LodePNGInfo 1795 1796 1797 12. changes 1798 ----------- 1799 1800 The version number of LodePNG is the date of the change given in the format 1801 yyyymmdd. 1802 1803 Some changes aren't backwards compatible. Those are indicated with a (!) 1804 symbol. 1805 1806 Not all changes are listed here, the commit history in github lists more: 1807 https://github.com/lvandeve/lodepng 1808 1809 *) 17 okt 2020: prevent decoding too large text/icc chunks by default. 1810 *) 06 mar 2020: simplified some of the dynamic memory allocations. 1811 *) 12 jan 2020: (!) added 'end' argument to lodepng_chunk_next to allow correct 1812 overflow checks. 1813 *) 14 aug 2019: around 25% faster decoding thanks to huffman lookup tables. 1814 *) 15 jun 2019: (!) auto_choose_color API changed (for bugfix: don't use palette 1815 if gray ICC profile) and non-ICC LodePNGColorProfile renamed to 1816 LodePNGColorStats. 1817 *) 30 dec 2018: code style changes only: removed newlines before opening braces. 1818 *) 10 sep 2018: added way to inspect metadata chunks without full decoding. 1819 *) 19 aug 2018: (!) fixed color mode bKGD is encoded with and made it use 1820 palette index in case of palette. 1821 *) 10 aug 2018: (!) added support for gAMA, cHRM, sRGB and iCCP chunks. This 1822 change is backwards compatible unless you relied on unknown_chunks for those. 1823 *) 11 jun 2018: less restrictive check for pixel size integer overflow 1824 *) 14 jan 2018: allow optionally ignoring a few more recoverable errors 1825 *) 17 sep 2017: fix memory leak for some encoder input error cases 1826 *) 27 nov 2016: grey+alpha auto color model detection bugfix 1827 *) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort). 1828 *) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within 1829 the limits of pure C90). 1830 *) 08 dec 2015: Made load_file function return error if file can't be opened. 1831 *) 24 okt 2015: Bugfix with decoding to palette output. 1832 *) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding. 1833 *) 24 aug 2014: Moved to github 1834 *) 23 aug 2014: Reduced needless memory usage of decoder. 1835 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for 1836 simplicity. Made ColorProfile public. 1837 *) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization. 1838 *) 22 dec 2013: Power of two windowsize required for optimization. 1839 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key. 1840 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png). 1841 *) 11 mar 2013: (!) Bugfix with custom free. Changed from "my" to "lodepng_" 1842 prefix for the custom allocators and made it possible with a new #define to 1843 use custom ones in your project without needing to change lodepng's code. 1844 *) 28 jan 2013: Bugfix with color key. 1845 *) 27 okt 2012: Tweaks in text chunk keyword length error handling. 1846 *) 8 okt 2012: (!) Added new filter strategy (entropy) and new auto color mode. 1847 (no palette). Better deflate tree encoding. New compression tweak settings. 1848 Faster color conversions while decoding. Some internal cleanups. 1849 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit. 1850 *) 1 sep 2012: (!) Removed #define's for giving custom (de)compression functions 1851 and made it work with function pointers instead. 1852 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc 1853 and free functions and toggle #defines from compiler flags. Small fixes. 1854 *) 6 may 2012: (!) Made plugging in custom zlib/deflate functions more flexible. 1855 *) 22 apr 2012: (!) Made interface more consistent, renaming a lot. Removed 1856 redundant C++ codec classes. Reduced amount of structs. Everything changed, 1857 but it is cleaner now imho and functionality remains the same. Also fixed 1858 several bugs and shrunk the implementation code. Made new samples. 1859 *) 6 nov 2011: (!) By default, the encoder now automatically chooses the best 1860 PNG color model and bit depth, based on the amount and type of colors of the 1861 raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color. 1862 *) 9 okt 2011: simpler hash chain implementation for the encoder. 1863 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching. 1864 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking. 1865 A bug with the PNG filtertype heuristic was fixed, so that it chooses much 1866 better ones (it's quite significant). A setting to do an experimental, slow, 1867 brute force search for PNG filter types is added. 1868 *) 17 aug 2011: (!) changed some C zlib related function names. 1869 *) 16 aug 2011: made the code less wide (max 120 characters per line). 1870 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors. 1871 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled. 1872 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman 1873 to optimize long sequences of zeros. 1874 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and 1875 LodePNG_InfoColor_canHaveAlpha functions for convenience. 1876 *) 7 nov 2010: added LodePNG_error_text function to get error code description. 1877 *) 30 okt 2010: made decoding slightly faster 1878 *) 26 okt 2010: (!) changed some C function and struct names (more consistent). 1879 Reorganized the documentation and the declaration order in the header. 1880 *) 08 aug 2010: only changed some comments and external samples. 1881 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version. 1882 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers. 1883 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could 1884 read by ignoring the problem but windows apps couldn't. 1885 *) 06 jun 2008: added more error checks for out of memory cases. 1886 *) 26 apr 2008: added a few more checks here and there to ensure more safety. 1887 *) 06 mar 2008: crash with encoding of strings fixed 1888 *) 02 feb 2008: support for international text chunks added (iTXt) 1889 *) 23 jan 2008: small cleanups, and #defines to divide code in sections 1890 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor. 1891 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder. 1892 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added 1893 Also various fixes, such as in the deflate and the padding bits code. 1894 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved 1895 filtering code of encoder. 1896 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A 1897 C++ wrapper around this provides an interface almost identical to before. 1898 Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code 1899 are together in these files but it works both for C and C++ compilers. 1900 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks 1901 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible 1902 *) 09 aug 2007: some VS2005 warnings removed again 1903 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code 1904 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images 1905 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing 1906 invalid std::vector element [0] fixed, and level 3 and 4 warnings removed 1907 *) 02 jun 2007: made the encoder add a tag with version by default 1908 *) 27 may 2007: zlib and png code separated (but still in the same file), 1909 simple encoder/decoder functions added for more simple usage cases 1910 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69), 1911 moved some examples from here to lodepng_examples.cpp 1912 *) 12 may 2007: palette decoding bug fixed 1913 *) 24 apr 2007: changed the license from BSD to the zlib license 1914 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks. 1915 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding 1916 palettized PNG images. Plus little interface change with palette and texts. 1917 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes. 1918 Fixed a bug where the end code of a block had length 0 in the Huffman tree. 1919 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented 1920 and supported by the encoder, resulting in smaller PNGs at the output. 1921 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone. 1922 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any 1923 greyscale type to 8-bit greyscale with or without alpha. 1924 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types 1925 to convert to and is more uniform. See the manual for how it works now. 1926 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days: 1927 encode/decode custom tEXt chunks, separate classes for zlib & deflate, and 1928 at last made the decoder give errors for incorrect Adler32 or Crc. 1929 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel. 1930 *) 29 dec 2006: Added support for encoding images without alpha channel, and 1931 cleaned out code as well as making certain parts faster. 1932 *) 28 dec 2006: Added "Settings" to the encoder. 1933 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now. 1934 Removed some code duplication in the decoder. Fixed little bug in an example. 1935 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter. 1936 Fixed a bug of the decoder with 16-bit per color. 1937 *) 15 okt 2006: Changed documentation structure 1938 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the 1939 given image buffer, however for now it's not compressed. 1940 *) 08 sep 2006: (!) Changed to interface with a Decoder class 1941 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different 1942 way. Renamed decodePNG to decodePNGGeneric. 1943 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a 1944 struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy. 1945 *) 28 jul 2006: Cleaned the code and added new error checks. 1946 Corrected terminology "deflate" into "inflate". 1947 *) 23 jun 2006: Added SDL example in the documentation in the header, this 1948 example allows easy debugging by displaying the PNG and its transparency. 1949 *) 22 jun 2006: (!) Changed way to obtain error value. Added 1950 loadFile function for convenience. Made decodePNG32 faster. 1951 *) 21 jun 2006: (!) Changed type of info vector to unsigned. 1952 Changed position of palette in info vector. Fixed an important bug that 1953 happened on PNGs with an uncompressed block. 1954 *) 16 jun 2006: Internally changed unsigned into unsigned where 1955 needed, and performed some optimizations. 1956 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them 1957 in LodePNG namespace. Changed the order of the parameters. Rewrote the 1958 documentation in the header. Renamed files to lodepng.cpp and lodepng.h 1959 *) 22 apr 2006: Optimized and improved some code 1960 *) 07 sep 2005: (!) Changed to std::vector interface 1961 *) 12 aug 2005: Initial release (C++, decoder only) 1962 1963 1964 13. contact information 1965 ----------------------- 1966 1967 Feel free to contact me with suggestions, problems, comments, ... concerning 1968 LodePNG. If you encounter a PNG image that doesn't work properly with this 1969 decoder, feel free to send it and I'll use it to find and fix the problem. 1970 1971 My email address is (puzzle the account and domain together with an @ symbol): 1972 Domain: gmail dot com. 1973 Account: lode dot vandevenne. 1974 1975 1976 Copyright (c) 2005-2020 Lode Vandevenne 1977 */ 1978