1 /* 2 LodePNG version 20180910 3 4 Copyright (c) 2005-2018 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 /*png encoder and png decoder*/ 48 #ifndef LODEPNG_NO_COMPILE_PNG 49 #define LODEPNG_COMPILE_PNG 50 #endif 51 /*deflate&zlib decoder and png decoder*/ 52 #ifndef LODEPNG_NO_COMPILE_DECODER 53 #define LODEPNG_COMPILE_DECODER 54 #endif 55 /*deflate&zlib encoder and png encoder*/ 56 #ifndef LODEPNG_NO_COMPILE_ENCODER 57 #define LODEPNG_COMPILE_ENCODER 58 #endif 59 /*the optional built in harddisk file loading and saving functions*/ 60 #ifndef LODEPNG_NO_COMPILE_DISK 61 #define LODEPNG_COMPILE_DISK 62 #endif 63 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/ 64 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS 65 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS 66 #endif 67 /*ability to convert error numerical codes to English text string*/ 68 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT 69 #define LODEPNG_COMPILE_ERROR_TEXT 70 #endif 71 /*Compile the default allocators (C's free, malloc and realloc). If you disable this, 72 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your 73 source files with custom allocators.*/ 74 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS 75 #define LODEPNG_COMPILE_ALLOCATORS 76 #endif 77 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/ 78 #ifdef __cplusplus 79 #ifndef LODEPNG_NO_COMPILE_CPP 80 #define LODEPNG_COMPILE_CPP 81 #endif 82 #endif 83 84 #ifdef LODEPNG_COMPILE_CPP 85 #include <vector> 86 #include <string> 87 #endif /*LODEPNG_COMPILE_CPP*/ 88 89 #ifdef LODEPNG_COMPILE_PNG 90 /*The PNG color types (also used for raw).*/ 91 typedef enum LodePNGColorType 92 { 93 LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/ 94 LCT_RGB = 2, /*RGB: 8,16 bit*/ 95 LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/ 96 LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/ 97 LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/ 98 } LodePNGColorType; 99 100 #ifdef LODEPNG_COMPILE_DECODER 101 /* 102 Converts PNG data in memory to raw pixel data. 103 out: Output parameter. Pointer to buffer that will contain the raw pixel data. 104 After decoding, its size is w * h * (bytes per pixel) bytes larger than 105 initially. Bytes per pixel depends on colortype and bitdepth. 106 Must be freed after usage with free(*out). 107 Note: for 16-bit per channel colors, uses big endian format like PNG does. 108 w: Output parameter. Pointer to width of pixel data. 109 h: Output parameter. Pointer to height of pixel data. 110 in: Memory buffer with the PNG file. 111 insize: size of the in buffer. 112 colortype: the desired color type for the raw output image. See explanation on PNG color types. 113 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types. 114 Return value: LodePNG error code (0 means no error). 115 */ 116 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, 117 const unsigned char* in, size_t insize, 118 LodePNGColorType colortype, unsigned bitdepth); 119 120 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/ 121 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, 122 const unsigned char* in, size_t insize); 123 124 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/ 125 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, 126 const unsigned char* in, size_t insize); 127 128 #ifdef LODEPNG_COMPILE_DISK 129 /* 130 Load PNG from disk, from file with given name. 131 Same as the other decode functions, but instead takes a filename as input. 132 */ 133 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, 134 const char* filename, 135 LodePNGColorType colortype, unsigned bitdepth); 136 137 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.*/ 138 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, 139 const char* filename); 140 141 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.*/ 142 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, 143 const char* filename); 144 #endif /*LODEPNG_COMPILE_DISK*/ 145 #endif /*LODEPNG_COMPILE_DECODER*/ 146 147 148 #ifdef LODEPNG_COMPILE_ENCODER 149 /* 150 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth 151 of the output PNG image cannot be chosen, they are automatically determined 152 by the colortype, bitdepth and content of the input pixel data. 153 Note: for 16-bit per channel colors, needs big endian format like PNG does. 154 out: Output parameter. Pointer to buffer that will contain the PNG image data. 155 Must be freed after usage with free(*out). 156 outsize: Output parameter. Pointer to the size in bytes of the out buffer. 157 image: The raw pixel data to encode. The size of this buffer should be 158 w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth. 159 w: width of the raw pixel data in pixels. 160 h: height of the raw pixel data in pixels. 161 colortype: the color type of the raw input image. See explanation on PNG color types. 162 bitdepth: the bit depth of the raw input image. See explanation on PNG color types. 163 Return value: LodePNG error code (0 means no error). 164 */ 165 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, 166 const unsigned char* image, unsigned w, unsigned h, 167 LodePNGColorType colortype, unsigned bitdepth); 168 169 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/ 170 unsigned lodepng_encode32(unsigned char** out, size_t* outsize, 171 const unsigned char* image, unsigned w, unsigned h); 172 173 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/ 174 unsigned lodepng_encode24(unsigned char** out, size_t* outsize, 175 const unsigned char* image, unsigned w, unsigned h); 176 177 #ifdef LODEPNG_COMPILE_DISK 178 /* 179 Converts raw pixel data into a PNG file on disk. 180 Same as the other encode functions, but instead takes a filename as output. 181 NOTE: This overwrites existing files without warning! 182 */ 183 unsigned lodepng_encode_file(const char* filename, 184 const unsigned char* image, unsigned w, unsigned h, 185 LodePNGColorType colortype, unsigned bitdepth); 186 187 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.*/ 188 unsigned lodepng_encode32_file(const char* filename, 189 const unsigned char* image, unsigned w, unsigned h); 190 191 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.*/ 192 unsigned lodepng_encode24_file(const char* filename, 193 const unsigned char* image, unsigned w, unsigned h); 194 #endif /*LODEPNG_COMPILE_DISK*/ 195 #endif /*LODEPNG_COMPILE_ENCODER*/ 196 197 198 #ifdef LODEPNG_COMPILE_CPP 199 namespace lodepng 200 { 201 #ifdef LODEPNG_COMPILE_DECODER 202 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype 203 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/ 204 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 205 const unsigned char* in, size_t insize, 206 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 207 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 208 const std::vector<unsigned char>& in, 209 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 210 #ifdef LODEPNG_COMPILE_DISK 211 /* 212 Converts PNG file from disk to raw pixel data in memory. 213 Same as the other decode functions, but instead takes a filename as input. 214 */ 215 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 216 const std::string& filename, 217 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 218 #endif /* LODEPNG_COMPILE_DISK */ 219 #endif /* LODEPNG_COMPILE_DECODER */ 220 221 #ifdef LODEPNG_COMPILE_ENCODER 222 /*Same as lodepng_encode_memory, but encodes to an std::vector. colortype 223 is that of the raw input data. The output PNG color type will be auto chosen.*/ 224 unsigned encode(std::vector<unsigned char>& out, 225 const unsigned char* in, unsigned w, unsigned h, 226 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 227 unsigned encode(std::vector<unsigned char>& out, 228 const std::vector<unsigned char>& in, unsigned w, unsigned h, 229 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 230 #ifdef LODEPNG_COMPILE_DISK 231 /* 232 Converts 32-bit RGBA raw pixel data into a PNG file on disk. 233 Same as the other encode functions, but instead takes a filename as output. 234 NOTE: This overwrites existing files without warning! 235 */ 236 unsigned encode(const std::string& filename, 237 const unsigned char* in, unsigned w, unsigned h, 238 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 239 unsigned encode(const std::string& filename, 240 const std::vector<unsigned char>& in, unsigned w, unsigned h, 241 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 242 #endif /* LODEPNG_COMPILE_DISK */ 243 #endif /* LODEPNG_COMPILE_ENCODER */ 244 } /* namespace lodepng */ 245 #endif /*LODEPNG_COMPILE_CPP*/ 246 #endif /*LODEPNG_COMPILE_PNG*/ 247 248 #ifdef LODEPNG_COMPILE_ERROR_TEXT 249 /*Returns an English description of the numerical error code.*/ 250 const char* lodepng_error_text(unsigned code); 251 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/ 252 253 #ifdef LODEPNG_COMPILE_DECODER 254 /*Settings for zlib decompression*/ 255 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; 256 struct LodePNGDecompressSettings 257 { 258 /* Check LodePNGDecoderSettings for more ignorable errors such as ignore_crc */ 259 unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ 260 261 /*use custom zlib decoder instead of built in one (default: null)*/ 262 unsigned (*custom_zlib)(unsigned char**, size_t*, 263 const unsigned char*, size_t, 264 const LodePNGDecompressSettings*); 265 /*use custom deflate decoder instead of built in one (default: null) 266 if custom_zlib is used, custom_deflate is ignored since only the built in 267 zlib function will call custom_deflate*/ 268 unsigned (*custom_inflate)(unsigned char**, size_t*, 269 const unsigned char*, size_t, 270 const LodePNGDecompressSettings*); 271 272 const void* custom_context; /*optional custom settings for custom functions*/ 273 }; 274 275 extern const LodePNGDecompressSettings lodepng_default_decompress_settings; 276 void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings); 277 #endif /*LODEPNG_COMPILE_DECODER*/ 278 279 #ifdef LODEPNG_COMPILE_ENCODER 280 /* 281 Settings for zlib compression. Tweaking these settings tweaks the balance 282 between speed and compression ratio. 283 */ 284 typedef struct LodePNGCompressSettings LodePNGCompressSettings; 285 struct LodePNGCompressSettings /*deflate = compress*/ 286 { 287 /*LZ77 related settings*/ 288 unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/ 289 unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ 290 unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/ 291 unsigned minmatch; /*mininum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ 292 unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/ 293 unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ 294 295 /*use custom zlib encoder instead of built in one (default: null)*/ 296 unsigned (*custom_zlib)(unsigned char**, size_t*, 297 const unsigned char*, size_t, 298 const LodePNGCompressSettings*); 299 /*use custom deflate encoder instead of built in one (default: null) 300 if custom_zlib is used, custom_deflate is ignored since only the built in 301 zlib function will call custom_deflate*/ 302 unsigned (*custom_deflate)(unsigned char**, size_t*, 303 const unsigned char*, size_t, 304 const LodePNGCompressSettings*); 305 306 const void* custom_context; /*optional custom settings for custom functions*/ 307 }; 308 309 extern const LodePNGCompressSettings lodepng_default_compress_settings; 310 void lodepng_compress_settings_init(LodePNGCompressSettings* settings); 311 #endif /*LODEPNG_COMPILE_ENCODER*/ 312 313 #ifdef LODEPNG_COMPILE_PNG 314 /* 315 Color mode of an image. Contains all information required to decode the pixel 316 bits to RGBA colors. This information is the same as used in the PNG file 317 format, and is used both for PNG and raw image data in LodePNG. 318 */ 319 typedef struct LodePNGColorMode 320 { 321 /*header (IHDR)*/ 322 LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/ 323 unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ 324 325 /* 326 palette (PLTE and tRNS) 327 328 Dynamically allocated with the colors of the palette, including alpha. 329 When encoding a PNG, to store your colors in the palette of the LodePNGColorMode, first use 330 lodepng_palette_clear, then for each color use lodepng_palette_add. 331 If you encode an image without alpha with palette, don't forget to put value 255 in each A byte of the palette. 332 333 When decoding, by default you can ignore this palette, since LodePNG already 334 fills the palette colors in the pixels of the raw RGBA output. 335 336 The palette is only supported for color type 3. 337 */ 338 unsigned char* palette; /*palette in RGBARGBA... order. When allocated, must be either 0, or have size 1024*/ 339 size_t palettesize; /*palette size in number of colors (amount of bytes is 4 * palettesize)*/ 340 341 /* 342 transparent color key (tRNS) 343 344 This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit. 345 For greyscale PNGs, r, g and b will all 3 be set to the same. 346 347 When decoding, by default you can ignore this information, since LodePNG sets 348 pixels with this key to transparent already in the raw RGBA output. 349 350 The color key is only supported for color types 0 and 2. 351 */ 352 unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ 353 unsigned key_r; /*red/greyscale component of color key*/ 354 unsigned key_g; /*green component of color key*/ 355 unsigned key_b; /*blue component of color key*/ 356 } LodePNGColorMode; 357 358 /*init, cleanup and copy functions to use with this struct*/ 359 void lodepng_color_mode_init(LodePNGColorMode* info); 360 void lodepng_color_mode_cleanup(LodePNGColorMode* info); 361 /*return value is error code (0 means no error)*/ 362 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source); 363 /* Makes a temporary LodePNGColorMode that does not need cleanup (no palette) */ 364 LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth); 365 366 void lodepng_palette_clear(LodePNGColorMode* info); 367 /*add 1 color to the palette*/ 368 unsigned lodepng_palette_add(LodePNGColorMode* info, 369 unsigned char r, unsigned char g, unsigned char b, unsigned char a); 370 371 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ 372 unsigned lodepng_get_bpp(const LodePNGColorMode* info); 373 /*get the amount of color channels used, based on colortype in the struct. 374 If a palette is used, it counts as 1 channel.*/ 375 unsigned lodepng_get_channels(const LodePNGColorMode* info); 376 /*is it a greyscale type? (only colortype 0 or 4)*/ 377 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info); 378 /*has it got an alpha channel? (only colortype 2 or 6)*/ 379 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info); 380 /*has it got a palette? (only colortype 3)*/ 381 unsigned lodepng_is_palette_type(const LodePNGColorMode* info); 382 /*only returns true if there is a palette and there is a value in the palette with alpha < 255. 383 Loops through the palette to check this.*/ 384 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info); 385 /* 386 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image. 387 Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels). 388 Returns false if the image can only have opaque pixels. 389 In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values, 390 or if "key_defined" is true. 391 */ 392 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info); 393 /*Returns the byte size of a raw image buffer with given width, height and color mode*/ 394 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color); 395 396 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 397 /*The information of a Time chunk in PNG.*/ 398 typedef struct LodePNGTime 399 { 400 unsigned year; /*2 bytes used (0-65535)*/ 401 unsigned month; /*1-12*/ 402 unsigned day; /*1-31*/ 403 unsigned hour; /*0-23*/ 404 unsigned minute; /*0-59*/ 405 unsigned second; /*0-60 (to allow for leap seconds)*/ 406 } LodePNGTime; 407 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 408 409 /*Information about the PNG image, except pixels, width and height.*/ 410 typedef struct LodePNGInfo 411 { 412 /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ 413 unsigned compression_method;/*compression method of the original file. Always 0.*/ 414 unsigned filter_method; /*filter method of the original file*/ 415 unsigned interlace_method; /*interlace method of the original file: 0=none, 1=Adam7*/ 416 LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/ 417 418 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 419 /* 420 Suggested background color chunk (bKGD) 421 422 This uses the same color mode and bit depth as the PNG (except no alpha channel), 423 with values truncated to the bit depth in the unsigned integer. 424 425 For greyscale and palette PNGs, the value is stored in background_r. The values 426 in background_g and background_b are then unused. 427 428 So when decoding, you may get these in a different color mode than the one you requested 429 for the raw pixels. 430 431 When encoding with auto_convert, you must use the color model defined in info_png.color for 432 these values. The encoder normally ignores info_png.color when auto_convert is on, but will 433 use it to interpret these values (and convert copies of them to its chosen color model). 434 435 When encoding, avoid setting this to an expensive color, such as a non-grey value 436 when the image is grey, or the compression will be worse since it will be forced to 437 write the PNG with a more expensive color mode (when auto_convert is on). 438 439 The decoder does not use this background color to edit the color of pixels. This is a 440 completely optional metadata feature. 441 */ 442 unsigned background_defined; /*is a suggested background color given?*/ 443 unsigned background_r; /*red/grey/palette component of suggested background color*/ 444 unsigned background_g; /*green component of suggested background color*/ 445 unsigned background_b; /*blue component of suggested background color*/ 446 447 /* 448 non-international text chunks (tEXt and zTXt) 449 450 The char** arrays each contain num strings. The actual messages are in 451 text_strings, while text_keys are keywords that give a short description what 452 the actual text represents, e.g. Title, Author, Description, or anything else. 453 454 All the string fields below including keys, names and language tags are null terminated. 455 The PNG specification uses null characters for the keys, names and tags, and forbids null 456 characters to appear in the main text which is why we can use null termination everywhere here. 457 458 A keyword is minimum 1 character and maximum 79 characters long. It's 459 discouraged to use a single line length longer than 79 characters for texts. 460 461 Don't allocate these text buffers yourself. Use the init/cleanup functions 462 correctly and use lodepng_add_text and lodepng_clear_text. 463 */ 464 size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/ 465 char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/ 466 char** text_strings; /*the actual text*/ 467 468 /* 469 international text chunks (iTXt) 470 Similar to the non-international text chunks, but with additional strings 471 "langtags" and "transkeys". 472 */ 473 size_t itext_num; /*the amount of international texts in this PNG*/ 474 char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ 475 char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/ 476 char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/ 477 char** itext_strings; /*the actual international text - UTF-8 string*/ 478 479 /*time chunk (tIME)*/ 480 unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ 481 LodePNGTime time; 482 483 /*phys chunk (pHYs)*/ 484 unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/ 485 unsigned phys_x; /*pixels per unit in x direction*/ 486 unsigned phys_y; /*pixels per unit in y direction*/ 487 unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ 488 489 /* 490 Color profile related chunks: gAMA, cHRM, sRGB, iCPP 491 492 LodePNG does not apply any color conversions on pixels in the encoder or decoder and does not interpret these color 493 profile values. It merely passes on the information. If you wish to use color profiles and convert colors, please 494 use these values with a color management library. 495 496 See the PNG, ICC and sRGB specifications for more information about the meaning of these values. 497 */ 498 499 /* gAMA chunk: optional, overridden by sRGB or iCCP if those are present. */ 500 unsigned gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */ 501 unsigned gama_gamma; /* Gamma exponent times 100000 */ 502 503 /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */ 504 unsigned chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */ 505 unsigned chrm_white_x; /* White Point x times 100000 */ 506 unsigned chrm_white_y; /* White Point y times 100000 */ 507 unsigned chrm_red_x; /* Red x times 100000 */ 508 unsigned chrm_red_y; /* Red y times 100000 */ 509 unsigned chrm_green_x; /* Green x times 100000 */ 510 unsigned chrm_green_y; /* Green y times 100000 */ 511 unsigned chrm_blue_x; /* Blue x times 100000 */ 512 unsigned chrm_blue_y; /* Blue y times 100000 */ 513 514 /* 515 sRGB chunk: optional. May not appear at the same time as iCCP. 516 If gAMA is also present gAMA must contain value 45455. 517 If cHRM is also present cHRM must contain respectively 31270,32900,64000,33000,30000,60000,15000,6000. 518 */ 519 unsigned srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */ 520 unsigned srgb_intent; /* Rendering intent: 0=perceptual, 1=rel. colorimetric, 2=saturation, 3=abs. colorimetric */ 521 522 /* 523 iCCP chunk: optional. May not appear at the same time as sRGB. 524 525 LodePNG does not parse or use the ICC profile (except its color space header field for an edge case), a 526 separate library to handle the ICC data (not included in LodePNG) format is needed to use it for color 527 management and conversions. 528 529 For encoding, if iCCP is present, gAMA and cHRM are recommended to be added as well with values that match the ICC 530 profile as closely as possible, if you wish to do this you should provide the correct values for gAMA and cHRM and 531 enable their '_defined' flags since LodePNG will not automatically compute them from the ICC profile. 532 533 For encoding, the ICC profile is required by the PNG specification to be an "RGB" profile for non-grey 534 PNG color types and a "GRAY" profile for grey PNG color types. If you disable auto_convert, you must ensure 535 the ICC profile type matches your requested color type, else the encoder gives an error. If auto_convert is 536 enabled (the default), and the ICC profile is not a good match for the pixel data, this will result in an encoder 537 error if the pixel data has non-grey pixels for a GRAY profile, or a silent less-optimal compression of the pixel 538 data if the pixels could be encoded as greyscale but the ICC profile is RGB. 539 540 To avoid this do not set an ICC profile in the image unless there is a good reason for it, and when doing so 541 make sure you compute it carefully to avoid the above problems. 542 */ 543 unsigned iccp_defined; /* Whether an iCCP chunk is present (0 = not present, 1 = present). */ 544 char* iccp_name; /* Null terminated string with profile name, 1-79 bytes */ 545 /* 546 The ICC profile in iccp_profile_size bytes. 547 Don't allocate this buffer yourself. Use the init/cleanup functions 548 correctly and use lodepng_set_icc and lodepng_clear_icc. 549 */ 550 unsigned char* iccp_profile; 551 unsigned iccp_profile_size; /* The size of iccp_profile in bytes */ 552 553 /* End of color profile related chunks */ 554 555 556 /* 557 unknown chunks: chunks not known by LodePNG, passed on byte for byte. 558 559 There are 3 buffers, one for each position in the PNG where unknown chunks can appear. 560 Each buffer contains all unknown chunks for that position consecutively. 561 The 3 positions are: 562 0: between IHDR and PLTE, 1: between PLTE and IDAT, 2: between IDAT and IEND. 563 564 For encoding, do not store critical chunks or known chunks that are enabled with a "_defined" flag 565 above in here, since the encoder will blindly follow this and could then encode an invalid PNG file 566 (such as one with two IHDR chunks or the disallowed combination of sRGB with iCCP). But do use 567 this if you wish to store an ancillary chunk that is not supported by LodePNG (such as sPLT or hIST), 568 or any non-standard PNG chunk. 569 570 Do not allocate or traverse this data yourself. Use the chunk traversing functions declared 571 later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct. 572 */ 573 unsigned char* unknown_chunks_data[3]; 574 size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ 575 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 576 } LodePNGInfo; 577 578 /*init, cleanup and copy functions to use with this struct*/ 579 void lodepng_info_init(LodePNGInfo* info); 580 void lodepng_info_cleanup(LodePNGInfo* info); 581 /*return value is error code (0 means no error)*/ 582 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source); 583 584 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 585 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/ 586 void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ 587 588 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag, 589 const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/ 590 void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ 591 592 /*replaces if exists*/ 593 unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size); 594 void lodepng_clear_icc(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ 595 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 596 597 /* 598 Converts raw buffer from one color type to another color type, based on 599 LodePNGColorMode structs to describe the input and output color type. 600 See the reference manual at the end of this header file to see which color conversions are supported. 601 return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported) 602 The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel 603 of the output color type (lodepng_get_bpp). 604 For < 8 bpp images, there should not be padding bits at the end of scanlines. 605 For 16-bit per channel colors, uses big endian format like PNG does. 606 Return value is LodePNG error code 607 */ 608 unsigned lodepng_convert(unsigned char* out, const unsigned char* in, 609 const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in, 610 unsigned w, unsigned h); 611 612 #ifdef LODEPNG_COMPILE_DECODER 613 /* 614 Settings for the decoder. This contains settings for the PNG and the Zlib 615 decoder, but not the Info settings from the Info structs. 616 */ 617 typedef struct LodePNGDecoderSettings 618 { 619 LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ 620 621 /* Check LodePNGDecompressSettings for more ignorable errors such as ignore_adler32 */ 622 unsigned ignore_crc; /*ignore CRC checksums*/ 623 unsigned ignore_critical; /*ignore unknown critical chunks*/ 624 unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/ 625 /* TODO: make a system involving warnings with levels and a strict mode instead. Other potentially recoverable 626 errors: srgb rendering intent value, size of content of ancillary chunks, more than 79 characters for some 627 strings, placement/combination rules for ancillary chunks, crc of unknown chunks, allowed characters 628 in string keys, etc... */ 629 630 unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ 631 632 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 633 unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/ 634 /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/ 635 unsigned remember_unknown_chunks; 636 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 637 } LodePNGDecoderSettings; 638 639 void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); 640 #endif /*LODEPNG_COMPILE_DECODER*/ 641 642 #ifdef LODEPNG_COMPILE_ENCODER 643 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ 644 typedef enum LodePNGFilterStrategy 645 { 646 /*every filter at zero*/ 647 LFS_ZERO, 648 /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/ 649 LFS_MINSUM, 650 /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending 651 on the image, this is better or worse than minsum.*/ 652 LFS_ENTROPY, 653 /* 654 Brute-force-search PNG filters by compressing each filter for each scanline. 655 Experimental, very slow, and only rarely gives better compression than MINSUM. 656 */ 657 LFS_BRUTE_FORCE, 658 /*use predefined_filters buffer: you specify the filter type for each scanline*/ 659 LFS_PREDEFINED 660 } LodePNGFilterStrategy; 661 662 /*Gives characteristics about the integer RGBA colors of the image (count, alpha channel usage, bit depth, ...), 663 which helps decide which color model to use for encoding. 664 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms. 665 NOTE: This is not related to the ICC color profile, search "iccp_profile" instead to find the ICC/chromacity/... 666 fields in this header file.*/ 667 typedef struct LodePNGColorProfile 668 { 669 unsigned colored; /*not greyscale*/ 670 unsigned key; /*image is not opaque and color key is possible instead of full alpha*/ 671 unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/ 672 unsigned short key_g; 673 unsigned short key_b; 674 unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/ 675 unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16.*/ 676 unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order*/ 677 unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for greyscale only. 16 if 16-bit per channel required.*/ 678 size_t numpixels; 679 } LodePNGColorProfile; 680 681 void lodepng_color_profile_init(LodePNGColorProfile* profile); 682 683 /*Get a LodePNGColorProfile of the image. The profile must already have been inited. 684 NOTE: This is not related to the ICC color profile, search "iccp_profile" instead to find the ICC/chromacity/... 685 fields in this header file.*/ 686 unsigned lodepng_get_color_profile(LodePNGColorProfile* profile, 687 const unsigned char* image, unsigned w, unsigned h, 688 const LodePNGColorMode* mode_in); 689 /*The function LodePNG uses internally to decide the PNG color with auto_convert. 690 Chooses an optimal color model, e.g. grey if only grey pixels, palette if < 256 colors, ...*/ 691 unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out, 692 const unsigned char* image, unsigned w, unsigned h, 693 const LodePNGColorMode* mode_in); 694 695 /*Settings for the encoder.*/ 696 typedef struct LodePNGEncoderSettings 697 { 698 LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ 699 700 unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/ 701 702 /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than 703 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to 704 completely follow the official PNG heuristic, filter_palette_zero must be true and 705 filter_strategy must be LFS_MINSUM*/ 706 unsigned filter_palette_zero; 707 /*Which filter strategy to use when not using zeroes due to filter_palette_zero. 708 Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/ 709 LodePNGFilterStrategy filter_strategy; 710 /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with 711 the same length as the amount of scanlines in the image, and each value must <= 5. You 712 have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero 713 must be set to 0 to ensure this is also used on palette or low bitdepth images.*/ 714 const unsigned char* predefined_filters; 715 716 /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). 717 If colortype is 3, PLTE is _always_ created.*/ 718 unsigned force_palette; 719 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 720 /*add LodePNG identifier and version as a text chunk, for debugging*/ 721 unsigned add_id; 722 /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ 723 unsigned text_compression; 724 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 725 } LodePNGEncoderSettings; 726 727 void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); 728 #endif /*LODEPNG_COMPILE_ENCODER*/ 729 730 731 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) 732 /*The settings, state and information for extended encoding and decoding.*/ 733 typedef struct LodePNGState 734 { 735 #ifdef LODEPNG_COMPILE_DECODER 736 LodePNGDecoderSettings decoder; /*the decoding settings*/ 737 #endif /*LODEPNG_COMPILE_DECODER*/ 738 #ifdef LODEPNG_COMPILE_ENCODER 739 LodePNGEncoderSettings encoder; /*the encoding settings*/ 740 #endif /*LODEPNG_COMPILE_ENCODER*/ 741 LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ 742 LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/ 743 unsigned error; 744 #ifdef LODEPNG_COMPILE_CPP 745 /* For the lodepng::State subclass. */ ~LodePNGStateLodePNGState746 virtual ~LodePNGState(){} 747 #endif 748 } LodePNGState; 749 750 /*init, cleanup and copy functions to use with this struct*/ 751 void lodepng_state_init(LodePNGState* state); 752 void lodepng_state_cleanup(LodePNGState* state); 753 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source); 754 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */ 755 756 #ifdef LODEPNG_COMPILE_DECODER 757 /* 758 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and 759 getting much more information about the PNG image and color mode. 760 */ 761 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, 762 LodePNGState* state, 763 const unsigned char* in, size_t insize); 764 765 /* 766 Read the PNG header, but not the actual data. This returns only the information 767 that is in the IHDR chunk of the PNG, such as width, height and color type. The 768 information is placed in the info_png field of the LodePNGState. 769 */ 770 unsigned lodepng_inspect(unsigned* w, unsigned* h, 771 LodePNGState* state, 772 const unsigned char* in, size_t insize); 773 #endif /*LODEPNG_COMPILE_DECODER*/ 774 775 /* 776 Reads one metadata chunk (other than IHDR) of the PNG file and outputs what it 777 read in the state. Returns error code on failure. 778 Use lodepng_inspect first with a new state, then e.g. lodepng_chunk_find_const 779 to find the desired chunk type, and if non null use lodepng_inspect_chunk (with 780 chunk_pointer - start_of_file as pos). 781 Supports most metadata chunks from the PNG standard (gAMA, bKGD, tEXt, ...). 782 Ignores unsupported, unknown, non-metadata or IHDR chunks (without error). 783 Requirements: &in[pos] must point to start of a chunk, must use regular 784 lodepng_inspect first since format of most other chunks depends on IHDR, and if 785 there is a PLTE chunk, that one must be inspected before tRNS or bKGD. 786 */ 787 unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos, 788 const unsigned char* in, size_t insize); 789 790 #ifdef LODEPNG_COMPILE_ENCODER 791 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ 792 unsigned lodepng_encode(unsigned char** out, size_t* outsize, 793 const unsigned char* image, unsigned w, unsigned h, 794 LodePNGState* state); 795 #endif /*LODEPNG_COMPILE_ENCODER*/ 796 797 /* 798 The lodepng_chunk functions are normally not needed, except to traverse the 799 unknown chunks stored in the LodePNGInfo struct, or add new ones to it. 800 It also allows traversing the chunks of an encoded PNG file yourself. 801 802 The chunk pointer always points to the beginning of the chunk itself, that is 803 the first byte of the 4 length bytes. 804 805 In the PNG file format, chunks have the following format: 806 -4 bytes length: length of the data of the chunk in bytes (chunk itself is 12 bytes longer) 807 -4 bytes chunk type (ASCII a-z,A-Z only, see below) 808 -length bytes of data (may be 0 bytes if length was 0) 809 -4 bytes of CRC, computed on chunk name + data 810 811 The first chunk starts at the 8th byte of the PNG file, the entire rest of the file 812 exists out of concatenated chunks with the above format. 813 814 PNG standard chunk ASCII naming conventions: 815 -First byte: uppercase = critical, lowercase = ancillary 816 -Second byte: uppercase = public, lowercase = private 817 -Third byte: must be uppercase 818 -Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy 819 */ 820 821 /* 822 Gets the length of the data of the chunk. Total chunk length has 12 bytes more. 823 There must be at least 4 bytes to read from. If the result value is too large, 824 it may be corrupt data. 825 */ 826 unsigned lodepng_chunk_length(const unsigned char* chunk); 827 828 /*puts the 4-byte type in null terminated string*/ 829 void lodepng_chunk_type(char type[5], const unsigned char* chunk); 830 831 /*check if the type is the given type*/ 832 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type); 833 834 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ 835 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk); 836 837 /*0: public, 1: private (see PNG standard)*/ 838 unsigned char lodepng_chunk_private(const unsigned char* chunk); 839 840 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ 841 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk); 842 843 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/ 844 unsigned char* lodepng_chunk_data(unsigned char* chunk); 845 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk); 846 847 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ 848 unsigned lodepng_chunk_check_crc(const unsigned char* chunk); 849 850 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ 851 void lodepng_chunk_generate_crc(unsigned char* chunk); 852 853 /* 854 Iterate to next chunks, allows iterating through all chunks of the PNG file. 855 Input must be at the beginning of a chunk (result of a previous lodepng_chunk_next call, 856 or the 8th byte of a PNG file which always has the first chunk), or alternatively may 857 point to the first byte of the PNG file (which is not a chunk but the magic header, the 858 function will then skip over it and return the first real chunk). 859 Expects at least 8 readable bytes of memory in the input pointer. 860 Will output pointer to the start of the next chunk or the end of the file if there 861 is no more chunk after this. Start this process at the 8th byte of the PNG file. 862 In a non-corrupt PNG file, the last chunk should have name "IEND". 863 */ 864 unsigned char* lodepng_chunk_next(unsigned char* chunk); 865 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk); 866 867 /*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/ 868 unsigned char* lodepng_chunk_find(unsigned char* chunk, const unsigned char* end, const char type[5]); 869 const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]); 870 871 /* 872 Appends chunk to the data in out. The given chunk should already have its chunk header. 873 The out variable and outlength are updated to reflect the new reallocated buffer. 874 Returns error code (0 if it went ok) 875 */ 876 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk); 877 878 /* 879 Appends new chunk to out. The chunk to append is given by giving its length, type 880 and data separately. The type is a 4-letter string. 881 The out variable and outlength are updated to reflect the new reallocated buffer. 882 Returne error code (0 if it went ok) 883 */ 884 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 885 const char* type, const unsigned char* data); 886 887 888 /*Calculate CRC32 of buffer*/ 889 unsigned lodepng_crc32(const unsigned char* buf, size_t len); 890 #endif /*LODEPNG_COMPILE_PNG*/ 891 892 893 #ifdef LODEPNG_COMPILE_ZLIB 894 /* 895 This zlib part can be used independently to zlib compress and decompress a 896 buffer. It cannot be used to create gzip files however, and it only supports the 897 part of zlib that is required for PNG, it does not support dictionaries. 898 */ 899 900 #ifdef LODEPNG_COMPILE_DECODER 901 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/ 902 unsigned lodepng_inflate(unsigned char** out, size_t* outsize, 903 const unsigned char* in, size_t insize, 904 const LodePNGDecompressSettings* settings); 905 906 /* 907 Decompresses Zlib data. Reallocates the out buffer and appends the data. The 908 data must be according to the zlib specification. 909 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 910 buffer and *outsize its size in bytes. out must be freed by user after usage. 911 */ 912 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, 913 const unsigned char* in, size_t insize, 914 const LodePNGDecompressSettings* settings); 915 #endif /*LODEPNG_COMPILE_DECODER*/ 916 917 #ifdef LODEPNG_COMPILE_ENCODER 918 /* 919 Compresses data with Zlib. Reallocates the out buffer and appends the data. 920 Zlib adds a small header and trailer around the deflate data. 921 The data is output in the format of the zlib specification. 922 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 923 buffer and *outsize its size in bytes. out must be freed by user after usage. 924 */ 925 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, 926 const unsigned char* in, size_t insize, 927 const LodePNGCompressSettings* settings); 928 929 /* 930 Find length-limited Huffman code for given frequencies. This function is in the 931 public interface only for tests, it's used internally by lodepng_deflate. 932 */ 933 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies, 934 size_t numcodes, unsigned maxbitlen); 935 936 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ 937 unsigned lodepng_deflate(unsigned char** out, size_t* outsize, 938 const unsigned char* in, size_t insize, 939 const LodePNGCompressSettings* settings); 940 941 #endif /*LODEPNG_COMPILE_ENCODER*/ 942 #endif /*LODEPNG_COMPILE_ZLIB*/ 943 944 #ifdef LODEPNG_COMPILE_DISK 945 /* 946 Load a file from disk into buffer. The function allocates the out buffer, and 947 after usage you should free it. 948 out: output parameter, contains pointer to loaded buffer. 949 outsize: output parameter, size of the allocated out buffer 950 filename: the path to the file to load 951 return value: error code (0 means ok) 952 */ 953 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename); 954 955 /* 956 Save a file from buffer to disk. Warning, if it exists, this function overwrites 957 the file without warning! 958 buffer: the buffer to write 959 buffersize: size of the buffer to write 960 filename: the path to the file to save to 961 return value: error code (0 means ok) 962 */ 963 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename); 964 #endif /*LODEPNG_COMPILE_DISK*/ 965 966 #ifdef LODEPNG_COMPILE_CPP 967 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */ 968 namespace lodepng 969 { 970 #ifdef LODEPNG_COMPILE_PNG 971 class State : public LodePNGState 972 { 973 public: 974 State(); 975 State(const State& other); 976 virtual ~State(); 977 State& operator=(const State& other); 978 }; 979 980 #ifdef LODEPNG_COMPILE_DECODER 981 /* Same as other lodepng::decode, but using a State for more settings and information. */ 982 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 983 State& state, 984 const unsigned char* in, size_t insize); 985 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 986 State& state, 987 const std::vector<unsigned char>& in); 988 #endif /*LODEPNG_COMPILE_DECODER*/ 989 990 #ifdef LODEPNG_COMPILE_ENCODER 991 /* Same as other lodepng::encode, but using a State for more settings and information. */ 992 unsigned encode(std::vector<unsigned char>& out, 993 const unsigned char* in, unsigned w, unsigned h, 994 State& state); 995 unsigned encode(std::vector<unsigned char>& out, 996 const std::vector<unsigned char>& in, unsigned w, unsigned h, 997 State& state); 998 #endif /*LODEPNG_COMPILE_ENCODER*/ 999 1000 #ifdef LODEPNG_COMPILE_DISK 1001 /* 1002 Load a file from disk into an std::vector. 1003 return value: error code (0 means ok) 1004 */ 1005 unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename); 1006 1007 /* 1008 Save the binary data in an std::vector to a file on disk. The file is overwritten 1009 without warning. 1010 */ 1011 unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename); 1012 #endif /* LODEPNG_COMPILE_DISK */ 1013 #endif /* LODEPNG_COMPILE_PNG */ 1014 1015 #ifdef LODEPNG_COMPILE_ZLIB 1016 #ifdef LODEPNG_COMPILE_DECODER 1017 /* Zlib-decompress an unsigned char buffer */ 1018 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 1019 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 1020 1021 /* Zlib-decompress an std::vector */ 1022 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 1023 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 1024 #endif /* LODEPNG_COMPILE_DECODER */ 1025 1026 #ifdef LODEPNG_COMPILE_ENCODER 1027 /* Zlib-compress an unsigned char buffer */ 1028 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 1029 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 1030 1031 /* Zlib-compress an std::vector */ 1032 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 1033 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 1034 #endif /* LODEPNG_COMPILE_ENCODER */ 1035 #endif /* LODEPNG_COMPILE_ZLIB */ 1036 } /* namespace lodepng */ 1037 #endif /*LODEPNG_COMPILE_CPP*/ 1038 1039 /* 1040 TODO: 1041 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often 1042 [.] check compatibility with various compilers - done but needs to be redone for every newer version 1043 [X] converting color to 16-bit per channel types 1044 [X] support color profile chunk types (but never let them touch RGB values by default) 1045 [ ] support all public PNG chunk types 1046 [ ] make sure encoder generates no chunks with size > (2^31)-1 1047 [ ] partial decoding (stream processing) 1048 [X] let the "isFullyOpaque" function check color keys and transparent palettes too 1049 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl" 1050 [ ] don't stop decoding on errors like 69, 57, 58 (make warnings) 1051 [ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ... 1052 [ ] errors with line numbers (and version) 1053 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes 1054 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ... 1055 [ ] allow user to give data (void*) to custom allocator 1056 */ 1057 1058 #endif /*LODEPNG_H inclusion guard*/ 1059 1060 /* 1061 LodePNG Documentation 1062 --------------------- 1063 1064 0. table of contents 1065 -------------------- 1066 1067 1. about 1068 1.1. supported features 1069 1.2. features not supported 1070 2. C and C++ version 1071 3. security 1072 4. decoding 1073 5. encoding 1074 6. color conversions 1075 6.1. PNG color types 1076 6.2. color conversions 1077 6.3. padding bits 1078 6.4. A note about 16-bits per channel and endianness 1079 7. error values 1080 8. chunks and PNG editing 1081 9. compiler support 1082 10. examples 1083 10.1. decoder C++ example 1084 10.2. decoder C example 1085 11. state settings reference 1086 12. changes 1087 13. contact information 1088 1089 1090 1. about 1091 -------- 1092 1093 PNG is a file format to store raster images losslessly with good compression, 1094 supporting different color types and alpha channel. 1095 1096 LodePNG is a PNG codec according to the Portable Network Graphics (PNG) 1097 Specification (Second Edition) - W3C Recommendation 10 November 2003. 1098 1099 The specifications used are: 1100 1101 *) Portable Network Graphics (PNG) Specification (Second Edition): 1102 http://www.w3.org/TR/2003/REC-PNG-20031110 1103 *) RFC 1950 ZLIB Compressed Data Format version 3.3: 1104 http://www.gzip.org/zlib/rfc-zlib.html 1105 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3: 1106 http://www.gzip.org/zlib/rfc-deflate.html 1107 1108 The most recent version of LodePNG can currently be found at 1109 http://lodev.org/lodepng/ 1110 1111 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds 1112 extra functionality. 1113 1114 LodePNG exists out of two files: 1115 -lodepng.h: the header file for both C and C++ 1116 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage 1117 1118 If you want to start using LodePNG right away without reading this doc, get the 1119 examples from the LodePNG website to see how to use it in code, or check the 1120 smaller examples in chapter 13 here. 1121 1122 LodePNG is simple but only supports the basic requirements. To achieve 1123 simplicity, the following design choices were made: There are no dependencies 1124 on any external library. There are functions to decode and encode a PNG with 1125 a single function call, and extended versions of these functions taking a 1126 LodePNGState struct allowing to specify or get more information. By default 1127 the colors of the raw image are always RGB or RGBA, no matter what color type 1128 the PNG file uses. To read and write files, there are simple functions to 1129 convert the files to/from buffers in memory. 1130 1131 This all makes LodePNG suitable for loading textures in games, demos and small 1132 programs, ... It's less suitable for full fledged image editors, loading PNGs 1133 over network (it requires all the image data to be available before decoding can 1134 begin), life-critical systems, ... 1135 1136 1.1. supported features 1137 ----------------------- 1138 1139 The following features are supported by the decoder: 1140 1141 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image, 1142 or the same color type as the PNG 1143 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image 1144 *) Adam7 interlace and deinterlace for any color type 1145 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk 1146 *) support for alpha channels, including RGBA color model, translucent palettes and color keying 1147 *) zlib decompression (inflate) 1148 *) zlib compression (deflate) 1149 *) CRC32 and ADLER32 checksums 1150 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks. 1151 *) the following chunks are supported (generated/interpreted) by both encoder and decoder: 1152 IHDR: header information 1153 PLTE: color palette 1154 IDAT: pixel data 1155 IEND: the final chunk 1156 tRNS: transparency for palettized images 1157 tEXt: textual information 1158 zTXt: compressed textual information 1159 iTXt: international textual information 1160 bKGD: suggested background color 1161 pHYs: physical dimensions 1162 tIME: modification time 1163 1164 1.2. features not supported 1165 --------------------------- 1166 1167 The following features are _not_ supported: 1168 1169 *) some features needed to make a conformant PNG-Editor might be still missing. 1170 *) partial loading/stream processing. All data must be available and is processed in one call. 1171 *) The following public chunks are not supported but treated as unknown chunks by LodePNG 1172 cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT 1173 Some of these are not supported on purpose: LodePNG wants to provide the RGB values 1174 stored in the pixels, not values modified by system dependent gamma or color models. 1175 1176 1177 2. C and C++ version 1178 -------------------- 1179 1180 The C version uses buffers allocated with alloc that you need to free() 1181 yourself. You need to use init and cleanup functions for each struct whenever 1182 using a struct from the C version to avoid exploits and memory leaks. 1183 1184 The C++ version has extra functions with std::vectors in the interface and the 1185 lodepng::State class which is a LodePNGState with constructor and destructor. 1186 1187 These files work without modification for both C and C++ compilers because all 1188 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers 1189 ignore it, and the C code is made to compile both with strict ISO C90 and C++. 1190 1191 To use the C++ version, you need to rename the source file to lodepng.cpp 1192 (instead of lodepng.c), and compile it with a C++ compiler. 1193 1194 To use the C version, you need to rename the source file to lodepng.c (instead 1195 of lodepng.cpp), and compile it with a C compiler. 1196 1197 1198 3. Security 1199 ----------- 1200 1201 Even if carefully designed, it's always possible that LodePNG contains possible 1202 exploits. If you discover one, please let me know, and it will be fixed. 1203 1204 When using LodePNG, care has to be taken with the C version of LodePNG, as well 1205 as the C-style structs when working with C++. The following conventions are used 1206 for all C-style structs: 1207 1208 -if a struct has a corresponding init function, always call the init function when making a new one 1209 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks 1210 -if a struct has a corresponding copy function, use the copy function instead of "=". 1211 The destination must also be inited already. 1212 1213 1214 4. Decoding 1215 ----------- 1216 1217 Decoding converts a PNG compressed image to a raw pixel buffer. 1218 1219 Most documentation on using the decoder is at its declarations in the header 1220 above. For C, simple decoding can be done with functions such as 1221 lodepng_decode32, and more advanced decoding can be done with the struct 1222 LodePNGState and lodepng_decode. For C++, all decoding can be done with the 1223 various lodepng::decode functions, and lodepng::State can be used for advanced 1224 features. 1225 1226 When using the LodePNGState, it uses the following fields for decoding: 1227 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here 1228 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get 1229 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use 1230 1231 LodePNGInfo info_png 1232 -------------------- 1233 1234 After decoding, this contains extra information of the PNG image, except the actual 1235 pixels, width and height because these are already gotten directly from the decoder 1236 functions. 1237 1238 It contains for example the original color type of the PNG image, text comments, 1239 suggested background color, etc... More details about the LodePNGInfo struct are 1240 at its declaration documentation. 1241 1242 LodePNGColorMode info_raw 1243 ------------------------- 1244 1245 When decoding, here you can specify which color type you want 1246 the resulting raw image to be. If this is different from the colortype of the 1247 PNG, then the decoder will automatically convert the result. This conversion 1248 always works, except if you want it to convert a color PNG to greyscale or to 1249 a palette with missing colors. 1250 1251 By default, 32-bit color is used for the result. 1252 1253 LodePNGDecoderSettings decoder 1254 ------------------------------ 1255 1256 The settings can be used to ignore the errors created by invalid CRC and Adler32 1257 chunks, and to disable the decoding of tEXt chunks. 1258 1259 There's also a setting color_convert, true by default. If false, no conversion 1260 is done, the resulting data will be as it was in the PNG (after decompression) 1261 and you'll have to puzzle the colors of the pixels together yourself using the 1262 color type information in the LodePNGInfo. 1263 1264 1265 5. Encoding 1266 ----------- 1267 1268 Encoding converts a raw pixel buffer to a PNG compressed image. 1269 1270 Most documentation on using the encoder is at its declarations in the header 1271 above. For C, simple encoding can be done with functions such as 1272 lodepng_encode32, and more advanced decoding can be done with the struct 1273 LodePNGState and lodepng_encode. For C++, all encoding can be done with the 1274 various lodepng::encode functions, and lodepng::State can be used for advanced 1275 features. 1276 1277 Like the decoder, the encoder can also give errors. However it gives less errors 1278 since the encoder input is trusted, the decoder input (a PNG image that could 1279 be forged by anyone) is not trusted. 1280 1281 When using the LodePNGState, it uses the following fields for encoding: 1282 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be. 1283 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has 1284 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use 1285 1286 LodePNGInfo info_png 1287 -------------------- 1288 1289 When encoding, you use this the opposite way as when decoding: for encoding, 1290 you fill in the values you want the PNG to have before encoding. By default it's 1291 not needed to specify a color type for the PNG since it's automatically chosen, 1292 but it's possible to choose it yourself given the right settings. 1293 1294 The encoder will not always exactly match the LodePNGInfo struct you give, 1295 it tries as close as possible. Some things are ignored by the encoder. The 1296 encoder uses, for example, the following settings from it when applicable: 1297 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the 1298 background color, the interlace method, unknown chunks, ... 1299 1300 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk. 1301 If the palette contains any colors for which the alpha channel is not 255 (so 1302 there are translucent colors in the palette), it'll add a tRNS chunk. 1303 1304 LodePNGColorMode info_raw 1305 ------------------------- 1306 1307 You specify the color type of the raw image that you give to the input here, 1308 including a possible transparent color key and palette you happen to be using in 1309 your raw image data. 1310 1311 By default, 32-bit color is assumed, meaning your input has to be in RGBA 1312 format with 4 bytes (unsigned chars) per pixel. 1313 1314 LodePNGEncoderSettings encoder 1315 ------------------------------ 1316 1317 The following settings are supported (some are in sub-structs): 1318 *) auto_convert: when this option is enabled, the encoder will 1319 automatically choose the smallest possible color mode (including color key) that 1320 can encode the colors of all pixels without information loss. 1321 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree, 1322 2 = dynamic huffman tree (best compression). Should be 2 for proper 1323 compression. 1324 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be 1325 true for proper compression. 1326 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value 1327 2048 by default, but can be set to 32768 for better, but slow, compression. 1328 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE 1329 chunk if force_palette is true. This can used as suggested palette to convert 1330 to by viewers that don't support more than 256 colors (if those still exist) 1331 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image. 1332 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks. 1333 zTXt chunks use zlib compression on the text. This gives a smaller result on 1334 large texts but a larger result on small texts (such as a single program name). 1335 It's all tEXt or all zTXt though, there's no separate setting per text yet. 1336 1337 1338 6. color conversions 1339 -------------------- 1340 1341 An important thing to note about LodePNG, is that the color type of the PNG, and 1342 the color type of the raw image, are completely independent. By default, when 1343 you decode a PNG, you get the result as a raw image in the color type you want, 1344 no matter whether the PNG was encoded with a palette, greyscale or RGBA color. 1345 And if you encode an image, by default LodePNG will automatically choose the PNG 1346 color type that gives good compression based on the values of colors and amount 1347 of colors in the image. It can be configured to let you control it instead as 1348 well, though. 1349 1350 To be able to do this, LodePNG does conversions from one color mode to another. 1351 It can convert from almost any color type to any other color type, except the 1352 following conversions: RGB to greyscale is not supported, and converting to a 1353 palette when the palette doesn't have a required color is not supported. This is 1354 not supported on purpose: this is information loss which requires a color 1355 reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to grey 1356 is easy, but there are multiple ways if you want to give some channels more 1357 weight). 1358 1359 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB 1360 color, no matter what color type the PNG has. And by default when encoding, 1361 LodePNG automatically picks the best color model for the output PNG, and expects 1362 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control 1363 the color format of the images yourself, you can skip this chapter. 1364 1365 6.1. PNG color types 1366 -------------------- 1367 1368 A PNG image can have many color types, ranging from 1-bit color to 64-bit color, 1369 as well as palettized color modes. After the zlib decompression and unfiltering 1370 in the PNG image is done, the raw pixel data will have that color type and thus 1371 a certain amount of bits per pixel. If you want the output raw image after 1372 decoding to have another color type, a conversion is done by LodePNG. 1373 1374 The PNG specification gives the following color types: 1375 1376 0: greyscale, bit depths 1, 2, 4, 8, 16 1377 2: RGB, bit depths 8 and 16 1378 3: palette, bit depths 1, 2, 4 and 8 1379 4: greyscale with alpha, bit depths 8 and 16 1380 6: RGBA, bit depths 8 and 16 1381 1382 Bit depth is the amount of bits per pixel per color channel. So the total amount 1383 of bits per pixel is: amount of channels * bitdepth. 1384 1385 6.2. color conversions 1386 ---------------------- 1387 1388 As explained in the sections about the encoder and decoder, you can specify 1389 color types and bit depths in info_png and info_raw to change the default 1390 behaviour. 1391 1392 If, when decoding, you want the raw image to be something else than the default, 1393 you need to set the color type and bit depth you want in the LodePNGColorMode, 1394 or the parameters colortype and bitdepth of the simple decoding function. 1395 1396 If, when encoding, you use another color type than the default in the raw input 1397 image, you need to specify its color type and bit depth in the LodePNGColorMode 1398 of the raw image, or use the parameters colortype and bitdepth of the simple 1399 encoding function. 1400 1401 If, when encoding, you don't want LodePNG to choose the output PNG color type 1402 but control it yourself, you need to set auto_convert in the encoder settings 1403 to false, and specify the color type you want in the LodePNGInfo of the 1404 encoder (including palette: it can generate a palette if auto_convert is true, 1405 otherwise not). 1406 1407 If the input and output color type differ (whether user chosen or auto chosen), 1408 LodePNG will do a color conversion, which follows the rules below, and may 1409 sometimes result in an error. 1410 1411 To avoid some confusion: 1412 -the decoder converts from PNG to raw image 1413 -the encoder converts from raw image to PNG 1414 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image 1415 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG 1416 -when encoding, the color type in LodePNGInfo is ignored if auto_convert 1417 is enabled, it is automatically generated instead 1418 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original 1419 PNG image, but it can be ignored since the raw image has the color type you requested instead 1420 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion 1421 between the color types is done if the color types are supported. If it is not 1422 supported, an error is returned. If the types are the same, no conversion is done. 1423 -even though some conversions aren't supported, LodePNG supports loading PNGs from any 1424 colortype and saving PNGs to any colortype, sometimes it just requires preparing 1425 the raw image correctly before encoding. 1426 -both encoder and decoder use the same color converter. 1427 1428 Non supported color conversions: 1429 -color to greyscale: no error is thrown, but the result will look ugly because 1430 only the red channel is taken 1431 -anything to palette when that palette does not have that color in it: in this 1432 case an error is thrown 1433 1434 Supported color conversions: 1435 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA 1436 -any grey or grey+alpha, to grey or grey+alpha 1437 -anything to a palette, as long as the palette has the requested colors in it 1438 -removing alpha channel 1439 -higher to smaller bitdepth, and vice versa 1440 1441 If you want no color conversion to be done (e.g. for speed or control): 1442 -In the encoder, you can make it save a PNG with any color type by giving the 1443 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to 1444 false. 1445 -In the decoder, you can make it store the pixel data in the same color type 1446 as the PNG has, by setting the color_convert setting to false. Settings in 1447 info_raw are then ignored. 1448 1449 The function lodepng_convert does the color conversion. It is available in the 1450 interface but normally isn't needed since the encoder and decoder already call 1451 it. 1452 1453 6.3. padding bits 1454 ----------------- 1455 1456 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines 1457 have a bit amount that isn't a multiple of 8, then padding bits are used so that each 1458 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output. 1459 The raw input image you give to the encoder, and the raw output image you get from the decoder 1460 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width 1461 of 7 pixels, the first pixel of the second scanline will the the 8th bit of the first byte, 1462 not the first bit of a new byte. 1463 1464 6.4. A note about 16-bits per channel and endianness 1465 ---------------------------------------------------- 1466 1467 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like 1468 for any other color format. The 16-bit values are stored in big endian (most 1469 significant byte first) in these arrays. This is the opposite order of the 1470 little endian used by x86 CPU's. 1471 1472 LodePNG always uses big endian because the PNG file format does so internally. 1473 Conversions to other formats than PNG uses internally are not supported by 1474 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit 1475 colors, the order in which you store R, G, B and A, and so on. Supporting and 1476 converting to/from all that is outside the scope of LodePNG. 1477 1478 This may mean that, depending on your use case, you may want to convert the big 1479 endian output of LodePNG to little endian with a for loop. This is certainly not 1480 always needed, many applications and libraries support big endian 16-bit colors 1481 anyway, but it means you cannot simply cast the unsigned char* buffer to an 1482 unsigned short* buffer on x86 CPUs. 1483 1484 1485 7. error values 1486 --------------- 1487 1488 All functions in LodePNG that return an error code, return 0 if everything went 1489 OK, or a non-zero code if there was an error. 1490 1491 The meaning of the LodePNG error values can be retrieved with the function 1492 lodepng_error_text: given the numerical error code, it returns a description 1493 of the error in English as a string. 1494 1495 Check the implementation of lodepng_error_text to see the meaning of each code. 1496 1497 1498 8. chunks and PNG editing 1499 ------------------------- 1500 1501 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG 1502 editor that should follow the rules about handling of unknown chunks, or if your 1503 program is able to read other types of chunks than the ones handled by LodePNG, 1504 then that's possible with the chunk functions of LodePNG. 1505 1506 A PNG chunk has the following layout: 1507 1508 4 bytes length 1509 4 bytes type name 1510 length bytes data 1511 4 bytes CRC 1512 1513 8.1. iterating through chunks 1514 ----------------------------- 1515 1516 If you have a buffer containing the PNG image data, then the first chunk (the 1517 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the 1518 signature of the PNG and are not part of a chunk. But if you start at byte 8 1519 then you have a chunk, and can check the following things of it. 1520 1521 NOTE: none of these functions check for memory buffer boundaries. To avoid 1522 exploits, always make sure the buffer contains all the data of the chunks. 1523 When using lodepng_chunk_next, make sure the returned value is within the 1524 allocated memory. 1525 1526 unsigned lodepng_chunk_length(const unsigned char* chunk): 1527 1528 Get the length of the chunk's data. The total chunk length is this length + 12. 1529 1530 void lodepng_chunk_type(char type[5], const unsigned char* chunk): 1531 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type): 1532 1533 Get the type of the chunk or compare if it's a certain type 1534 1535 unsigned char lodepng_chunk_critical(const unsigned char* chunk): 1536 unsigned char lodepng_chunk_private(const unsigned char* chunk): 1537 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk): 1538 1539 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are). 1540 Check if the chunk is private (public chunks are part of the standard, private ones not). 1541 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical 1542 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your 1543 program doesn't handle that type of unknown chunk. 1544 1545 unsigned char* lodepng_chunk_data(unsigned char* chunk): 1546 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk): 1547 1548 Get a pointer to the start of the data of the chunk. 1549 1550 unsigned lodepng_chunk_check_crc(const unsigned char* chunk): 1551 void lodepng_chunk_generate_crc(unsigned char* chunk): 1552 1553 Check if the crc is correct or generate a correct one. 1554 1555 unsigned char* lodepng_chunk_next(unsigned char* chunk): 1556 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk): 1557 1558 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these 1559 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough 1560 data available in the buffer to be able to go to the next chunk. 1561 1562 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk): 1563 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 1564 const char* type, const unsigned char* data): 1565 1566 These functions are used to create new chunks that are appended to the data in *out that has 1567 length *outlength. The append function appends an existing chunk to the new data. The create 1568 function creates a new chunk with the given parameters and appends it. Type is the 4-letter 1569 name of the chunk. 1570 1571 8.2. chunks in info_png 1572 ----------------------- 1573 1574 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3 1575 buffers (each with size) to contain 3 types of unknown chunks: 1576 the ones that come before the PLTE chunk, the ones that come between the PLTE 1577 and the IDAT chunks, and the ones that come after the IDAT chunks. 1578 It's necessary to make the distionction between these 3 cases because the PNG 1579 standard forces to keep the ordering of unknown chunks compared to the critical 1580 chunks, but does not force any other ordering rules. 1581 1582 info_png.unknown_chunks_data[0] is the chunks before PLTE 1583 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT 1584 info_png.unknown_chunks_data[2] is the chunks after IDAT 1585 1586 The chunks in these 3 buffers can be iterated through and read by using the same 1587 way described in the previous subchapter. 1588 1589 When using the decoder to decode a PNG, you can make it store all unknown chunks 1590 if you set the option settings.remember_unknown_chunks to 1. By default, this 1591 option is off (0). 1592 1593 The encoder will always encode unknown chunks that are stored in the info_png. 1594 If you need it to add a particular chunk that isn't known by LodePNG, you can 1595 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in 1596 info_png.unknown_chunks_data[x]. 1597 1598 Chunks that are known by LodePNG should not be added in that way. E.g. to make 1599 LodePNG add a bKGD chunk, set background_defined to true and add the correct 1600 parameters there instead. 1601 1602 1603 9. compiler support 1604 ------------------- 1605 1606 No libraries other than the current standard C library are needed to compile 1607 LodePNG. For the C++ version, only the standard C++ library is needed on top. 1608 Add the files lodepng.c(pp) and lodepng.h to your project, include 1609 lodepng.h where needed, and your program can read/write PNG files. 1610 1611 It is compatible with C90 and up, and C++03 and up. 1612 1613 If performance is important, use optimization when compiling! For both the 1614 encoder and decoder, this makes a large difference. 1615 1616 Make sure that LodePNG is compiled with the same compiler of the same version 1617 and with the same settings as the rest of the program, or the interfaces with 1618 std::vectors and std::strings in C++ can be incompatible. 1619 1620 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets. 1621 1622 *) gcc and g++ 1623 1624 LodePNG is developed in gcc so this compiler is natively supported. It gives no 1625 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++ 1626 version 4.7.1 on Linux, 32-bit and 64-bit. 1627 1628 *) Clang 1629 1630 Fully supported and warning-free. 1631 1632 *) Mingw 1633 1634 The Mingw compiler (a port of gcc for Windows) should be fully supported by 1635 LodePNG. 1636 1637 *) Visual Studio and Visual C++ Express Edition 1638 1639 LodePNG should be warning-free with warning level W4. Two warnings were disabled 1640 with pragmas though: warning 4244 about implicit conversions, and warning 4996 1641 where it wants to use a non-standard function fopen_s instead of the standard C 1642 fopen. 1643 1644 Visual Studio may want "stdafx.h" files to be included in each source file and 1645 give an error "unexpected end of file while looking for precompiled header". 1646 This is not standard C++ and will not be added to the stock LodePNG. You can 1647 disable it for lodepng.cpp only by right clicking it, Properties, C/C++, 1648 Precompiled Headers, and set it to Not Using Precompiled Headers there. 1649 1650 NOTE: Modern versions of VS should be fully supported, but old versions, e.g. 1651 VS6, are not guaranteed to work. 1652 1653 *) Compilers on Macintosh 1654 1655 LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for 1656 C and C++. 1657 1658 *) Other Compilers 1659 1660 If you encounter problems on any compilers, feel free to let me know and I may 1661 try to fix it if the compiler is modern and standards complient. 1662 1663 1664 10. examples 1665 ------------ 1666 1667 This decoder example shows the most basic usage of LodePNG. More complex 1668 examples can be found on the LodePNG website. 1669 1670 10.1. decoder C++ example 1671 ------------------------- 1672 1673 #include "lodepng.h" 1674 #include <iostream> 1675 1676 int main(int argc, char *argv[]) 1677 { 1678 const char* filename = argc > 1 ? argv[1] : "test.png"; 1679 1680 //load and decode 1681 std::vector<unsigned char> image; 1682 unsigned width, height; 1683 unsigned error = lodepng::decode(image, width, height, filename); 1684 1685 //if there's an error, display it 1686 if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl; 1687 1688 //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ... 1689 } 1690 1691 10.2. decoder C example 1692 ----------------------- 1693 1694 #include "lodepng.h" 1695 1696 int main(int argc, char *argv[]) 1697 { 1698 unsigned error; 1699 unsigned char* image; 1700 size_t width, height; 1701 const char* filename = argc > 1 ? argv[1] : "test.png"; 1702 1703 error = lodepng_decode32_file(&image, &width, &height, filename); 1704 1705 if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error)); 1706 1707 / * use image here * / 1708 1709 free(image); 1710 return 0; 1711 } 1712 1713 11. state settings reference 1714 ---------------------------- 1715 1716 A quick reference of some settings to set on the LodePNGState 1717 1718 For decoding: 1719 1720 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums 1721 state.decoder.zlibsettings.custom_...: use custom inflate function 1722 state.decoder.ignore_crc: ignore CRC checksums 1723 state.decoder.ignore_critical: ignore unknown critical chunks 1724 state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors 1725 state.decoder.color_convert: convert internal PNG color to chosen one 1726 state.decoder.read_text_chunks: whether to read in text metadata chunks 1727 state.decoder.remember_unknown_chunks: whether to read in unknown chunks 1728 state.info_raw.colortype: desired color type for decoded image 1729 state.info_raw.bitdepth: desired bit depth for decoded image 1730 state.info_raw....: more color settings, see struct LodePNGColorMode 1731 state.info_png....: no settings for decoder but ouput, see struct LodePNGInfo 1732 1733 For encoding: 1734 1735 state.encoder.zlibsettings.btype: disable compression by setting it to 0 1736 state.encoder.zlibsettings.use_lz77: use LZ77 in compression 1737 state.encoder.zlibsettings.windowsize: tweak LZ77 windowsize 1738 state.encoder.zlibsettings.minmatch: tweak min LZ77 length to match 1739 state.encoder.zlibsettings.nicematch: tweak LZ77 match where to stop searching 1740 state.encoder.zlibsettings.lazymatching: try one more LZ77 matching 1741 state.encoder.zlibsettings.custom_...: use custom deflate function 1742 state.encoder.auto_convert: choose optimal PNG color type, if 0 uses info_png 1743 state.encoder.filter_palette_zero: PNG filter strategy for palette 1744 state.encoder.filter_strategy: PNG filter strategy to encode with 1745 state.encoder.force_palette: add palette even if not encoding to one 1746 state.encoder.add_id: add LodePNG identifier and version as a text chunk 1747 state.encoder.text_compression: use compressed text chunks for metadata 1748 state.info_raw.colortype: color type of raw input image you provide 1749 state.info_raw.bitdepth: bit depth of raw input image you provide 1750 state.info_raw: more color settings, see struct LodePNGColorMode 1751 state.info_png.color.colortype: desired color type if auto_convert is false 1752 state.info_png.color.bitdepth: desired bit depth if auto_convert is false 1753 state.info_png.color....: more color settings, see struct LodePNGColorMode 1754 state.info_png....: more PNG related settings, see struct LodePNGInfo 1755 1756 1757 12. changes 1758 ----------- 1759 1760 The version number of LodePNG is the date of the change given in the format 1761 yyyymmdd. 1762 1763 Some changes aren't backwards compatible. Those are indicated with a (!) 1764 symbol. 1765 1766 *) 10 sep 2018: added way to inspect metadata chunks without full decoding. 1767 *) 19 aug 2018 (!): fixed color mode bKGD is encoded with and made it use 1768 palette index in case of palette. 1769 *) 10 aug 2018 (!): added support for gAMA, cHRM, sRGB and iCCP chunks. This 1770 change is backwards compatible unless you relied on unknown_chunks for those. 1771 *) 11 jun 2018: less restrictive check for pixel size integer overflow 1772 *) 14 jan 2018: allow optionally ignoring a few more recoverable errors 1773 *) 17 sep 2017: fix memory leak for some encoder input error cases 1774 *) 27 nov 2016: grey+alpha auto color model detection bugfix 1775 *) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort). 1776 *) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within 1777 the limits of pure C90). 1778 *) 08 dec 2015: Made load_file function return error if file can't be opened. 1779 *) 24 okt 2015: Bugfix with decoding to palette output. 1780 *) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding. 1781 *) 23 aug 2014: Reduced needless memory usage of decoder. 1782 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for 1783 simplicity. Made ColorProfile public. 1784 *) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization. 1785 *) 22 dec 2013: Power of two windowsize required for optimization. 1786 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key. 1787 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png). 1788 *) 11 mar 2013 (!): Bugfix with custom free. Changed from "my" to "lodepng_" 1789 prefix for the custom allocators and made it possible with a new #define to 1790 use custom ones in your project without needing to change lodepng's code. 1791 *) 28 jan 2013: Bugfix with color key. 1792 *) 27 okt 2012: Tweaks in text chunk keyword length error handling. 1793 *) 8 okt 2012 (!): Added new filter strategy (entropy) and new auto color mode. 1794 (no palette). Better deflate tree encoding. New compression tweak settings. 1795 Faster color conversions while decoding. Some internal cleanups. 1796 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit. 1797 *) 1 sep 2012 (!): Removed #define's for giving custom (de)compression functions 1798 and made it work with function pointers instead. 1799 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc 1800 and free functions and toggle #defines from compiler flags. Small fixes. 1801 *) 6 may 2012 (!): Made plugging in custom zlib/deflate functions more flexible. 1802 *) 22 apr 2012 (!): Made interface more consistent, renaming a lot. Removed 1803 redundant C++ codec classes. Reduced amount of structs. Everything changed, 1804 but it is cleaner now imho and functionality remains the same. Also fixed 1805 several bugs and shrunk the implementation code. Made new samples. 1806 *) 6 nov 2011 (!): By default, the encoder now automatically chooses the best 1807 PNG color model and bit depth, based on the amount and type of colors of the 1808 raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color. 1809 *) 9 okt 2011: simpler hash chain implementation for the encoder. 1810 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching. 1811 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking. 1812 A bug with the PNG filtertype heuristic was fixed, so that it chooses much 1813 better ones (it's quite significant). A setting to do an experimental, slow, 1814 brute force search for PNG filter types is added. 1815 *) 17 aug 2011 (!): changed some C zlib related function names. 1816 *) 16 aug 2011: made the code less wide (max 120 characters per line). 1817 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors. 1818 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled. 1819 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman 1820 to optimize long sequences of zeros. 1821 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and 1822 LodePNG_InfoColor_canHaveAlpha functions for convenience. 1823 *) 7 nov 2010: added LodePNG_error_text function to get error code description. 1824 *) 30 okt 2010: made decoding slightly faster 1825 *) 26 okt 2010: (!) changed some C function and struct names (more consistent). 1826 Reorganized the documentation and the declaration order in the header. 1827 *) 08 aug 2010: only changed some comments and external samples. 1828 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version. 1829 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers. 1830 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could 1831 read by ignoring the problem but windows apps couldn't. 1832 *) 06 jun 2008: added more error checks for out of memory cases. 1833 *) 26 apr 2008: added a few more checks here and there to ensure more safety. 1834 *) 06 mar 2008: crash with encoding of strings fixed 1835 *) 02 feb 2008: support for international text chunks added (iTXt) 1836 *) 23 jan 2008: small cleanups, and #defines to divide code in sections 1837 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor. 1838 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder. 1839 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added 1840 Also various fixes, such as in the deflate and the padding bits code. 1841 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved 1842 filtering code of encoder. 1843 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A 1844 C++ wrapper around this provides an interface almost identical to before. 1845 Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code 1846 are together in these files but it works both for C and C++ compilers. 1847 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks 1848 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible 1849 *) 09 aug 2007: some VS2005 warnings removed again 1850 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code 1851 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images 1852 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing 1853 invalid std::vector element [0] fixed, and level 3 and 4 warnings removed 1854 *) 02 jun 2007: made the encoder add a tag with version by default 1855 *) 27 may 2007: zlib and png code separated (but still in the same file), 1856 simple encoder/decoder functions added for more simple usage cases 1857 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69), 1858 moved some examples from here to lodepng_examples.cpp 1859 *) 12 may 2007: palette decoding bug fixed 1860 *) 24 apr 2007: changed the license from BSD to the zlib license 1861 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks. 1862 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding 1863 palettized PNG images. Plus little interface change with palette and texts. 1864 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes. 1865 Fixed a bug where the end code of a block had length 0 in the Huffman tree. 1866 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented 1867 and supported by the encoder, resulting in smaller PNGs at the output. 1868 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone. 1869 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any 1870 greyscale type to 8-bit greyscale with or without alpha. 1871 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types 1872 to convert to and is more uniform. See the manual for how it works now. 1873 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days: 1874 encode/decode custom tEXt chunks, separate classes for zlib & deflate, and 1875 at last made the decoder give errors for incorrect Adler32 or Crc. 1876 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel. 1877 *) 29 dec 2006: Added support for encoding images without alpha channel, and 1878 cleaned out code as well as making certain parts faster. 1879 *) 28 dec 2006: Added "Settings" to the encoder. 1880 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now. 1881 Removed some code duplication in the decoder. Fixed little bug in an example. 1882 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter. 1883 Fixed a bug of the decoder with 16-bit per color. 1884 *) 15 okt 2006: Changed documentation structure 1885 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the 1886 given image buffer, however for now it's not compressed. 1887 *) 08 sep 2006: (!) Changed to interface with a Decoder class 1888 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different 1889 way. Renamed decodePNG to decodePNGGeneric. 1890 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a 1891 struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy. 1892 *) 28 jul 2006: Cleaned the code and added new error checks. 1893 Corrected terminology "deflate" into "inflate". 1894 *) 23 jun 2006: Added SDL example in the documentation in the header, this 1895 example allows easy debugging by displaying the PNG and its transparency. 1896 *) 22 jun 2006: (!) Changed way to obtain error value. Added 1897 loadFile function for convenience. Made decodePNG32 faster. 1898 *) 21 jun 2006: (!) Changed type of info vector to unsigned. 1899 Changed position of palette in info vector. Fixed an important bug that 1900 happened on PNGs with an uncompressed block. 1901 *) 16 jun 2006: Internally changed unsigned into unsigned where 1902 needed, and performed some optimizations. 1903 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them 1904 in LodePNG namespace. Changed the order of the parameters. Rewrote the 1905 documentation in the header. Renamed files to lodepng.cpp and lodepng.h 1906 *) 22 apr 2006: Optimized and improved some code 1907 *) 07 sep 2005: (!) Changed to std::vector interface 1908 *) 12 aug 2005: Initial release (C++, decoder only) 1909 1910 1911 13. contact information 1912 ----------------------- 1913 1914 Feel free to contact me with suggestions, problems, comments, ... concerning 1915 LodePNG. If you encounter a PNG image that doesn't work properly with this 1916 decoder, feel free to send it and I'll use it to find and fix the problem. 1917 1918 My email address is (puzzle the account and domain together with an @ symbol): 1919 Domain: gmail dot com. 1920 Account: lode dot vandevenne. 1921 1922 1923 Copyright (c) 2005-2018 Lode Vandevenne 1924 */ 1925