1 /* 2 LodePNG version 20140823 3 4 Copyright (c) 2005-2014 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 #ifdef __cplusplus 32 #include <vector> 33 #include <string> 34 #endif /*__cplusplus*/ 35 36 /* 37 The following #defines are used to create code sections. They can be disabled 38 to disable code sections, which can give faster compile time and smaller binary. 39 The "NO_COMPILE" defines are designed to be used to pass as defines to the 40 compiler command to disable them without modifying this header, e.g. 41 -DLODEPNG_NO_COMPILE_ZLIB for gcc. 42 */ 43 /*deflate & zlib. If disabled, you must specify alternative zlib functions in 44 the custom_zlib field of the compress and decompress settings*/ 45 #ifndef LODEPNG_NO_COMPILE_ZLIB 46 #define LODEPNG_COMPILE_ZLIB 47 #endif 48 /*png encoder and png decoder*/ 49 #ifndef LODEPNG_NO_COMPILE_PNG 50 #define LODEPNG_COMPILE_PNG 51 #endif 52 /*deflate&zlib decoder and png decoder*/ 53 #ifndef LODEPNG_NO_COMPILE_DECODER 54 #define LODEPNG_COMPILE_DECODER 55 #endif 56 /*deflate&zlib encoder and png encoder*/ 57 #ifndef LODEPNG_NO_COMPILE_ENCODER 58 #define LODEPNG_COMPILE_ENCODER 59 #endif 60 /*the optional built in harddisk file loading and saving functions*/ 61 #ifndef LODEPNG_NO_COMPILE_DISK 62 #define LODEPNG_COMPILE_DISK 63 #endif 64 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/ 65 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS 66 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS 67 #endif 68 /*ability to convert error numerical codes to English text string*/ 69 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT 70 #define LODEPNG_COMPILE_ERROR_TEXT 71 #endif 72 73 #ifdef LODEPNG_COMPILE_PNG 74 /*The PNG color types (also used for raw).*/ 75 typedef enum LodePNGColorType 76 { 77 LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/ 78 LCT_RGB = 2, /*RGB: 8,16 bit*/ 79 LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/ 80 LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/ 81 LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/ 82 } LodePNGColorType; 83 84 #ifdef LODEPNG_COMPILE_DECODER 85 /* 86 Converts PNG data in memory to raw pixel data. 87 out: Output parameter. Pointer to buffer that will contain the raw pixel data. 88 After decoding, its size is w * h * (bytes per pixel) bytes larger than 89 initially. Bytes per pixel depends on colortype and bitdepth. 90 Must be freed after usage with free(*out). 91 Note: for 16-bit per channel colors, uses big endian format like PNG does. 92 w: Output parameter. Pointer to width of pixel data. 93 h: Output parameter. Pointer to height of pixel data. 94 in: Memory buffer with the PNG file. 95 insize: size of the in buffer. 96 colortype: the desired color type for the raw output image. See explanation on PNG color types. 97 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types. 98 Return value: LodePNG error code (0 means no error). 99 */ 100 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, 101 const unsigned char* in, size_t insize, LodePNGColorType colortype, 102 unsigned bitdepth); 103 104 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/ 105 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, 106 size_t insize); 107 108 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/ 109 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, const unsigned char* in, 110 size_t insize); 111 112 #ifdef LODEPNG_COMPILE_DISK 113 /* 114 Load PNG from disk, from file with given name. 115 Same as the other decode functions, but instead takes a filename as input. 116 */ 117 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename, 118 LodePNGColorType colortype, unsigned bitdepth); 119 120 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.*/ 121 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename); 122 123 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.*/ 124 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename); 125 #endif /*LODEPNG_COMPILE_DISK*/ 126 #endif /*LODEPNG_COMPILE_DECODER*/ 127 128 #ifdef LODEPNG_COMPILE_ENCODER 129 /* 130 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth 131 of the output PNG image cannot be chosen, they are automatically determined 132 by the colortype, bitdepth and content of the input pixel data. 133 Note: for 16-bit per channel colors, needs big endian format like PNG does. 134 out: Output parameter. Pointer to buffer that will contain the PNG image data. 135 Must be freed after usage with free(*out). 136 outsize: Output parameter. Pointer to the size in bytes of the out buffer. 137 image: The raw pixel data to encode. The size of this buffer should be 138 w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth. 139 w: width of the raw pixel data in pixels. 140 h: height of the raw pixel data in pixels. 141 colortype: the color type of the raw input image. See explanation on PNG color types. 142 bitdepth: the bit depth of the raw input image. See explanation on PNG color types. 143 Return value: LodePNG error code (0 means no error). 144 */ 145 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, const unsigned char* image, 146 unsigned w, unsigned h, LodePNGColorType colortype, 147 unsigned bitdepth); 148 149 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/ 150 unsigned lodepng_encode32(unsigned char** out, size_t* outsize, const unsigned char* image, 151 unsigned w, unsigned h); 152 153 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/ 154 unsigned lodepng_encode24(unsigned char** out, size_t* outsize, const unsigned char* image, 155 unsigned w, unsigned h); 156 157 #ifdef LODEPNG_COMPILE_DISK 158 /* 159 Converts raw pixel data into a PNG file on disk. 160 Same as the other encode functions, but instead takes a filename as output. 161 NOTE: This overwrites existing files without warning! 162 */ 163 unsigned lodepng_encode_file(const char* filename, const unsigned char* image, unsigned w, 164 unsigned h, LodePNGColorType colortype, unsigned bitdepth); 165 166 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.*/ 167 unsigned lodepng_encode32_file(const char* filename, const unsigned char* image, unsigned w, 168 unsigned h); 169 170 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.*/ 171 unsigned lodepng_encode24_file(const char* filename, const unsigned char* image, unsigned w, 172 unsigned h); 173 #endif /*LODEPNG_COMPILE_DISK*/ 174 #endif /*LODEPNG_COMPILE_ENCODER*/ 175 #endif /*LODEPNG_COMPILE_PNG*/ 176 177 #ifdef LODEPNG_COMPILE_ERROR_TEXT 178 /*Returns an English description of the numerical error code.*/ 179 const char* lodepng_error_text(unsigned code); 180 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/ 181 182 #ifdef LODEPNG_COMPILE_DECODER 183 /*Settings for zlib decompression*/ 184 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; 185 struct LodePNGDecompressSettings 186 { 187 unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 188 checksum is corrupted*/ 189 190 /*use custom zlib decoder instead of built in one (default: null)*/ 191 unsigned (*custom_zlib)(unsigned char**, size_t*, const unsigned char*, size_t, 192 const LodePNGDecompressSettings*); 193 /*use custom deflate decoder instead of built in one (default: null) 194 if custom_zlib is used, custom_deflate is ignored since only the built in 195 zlib function will call custom_deflate*/ 196 unsigned (*custom_inflate)(unsigned char**, size_t*, const unsigned char*, size_t, 197 const LodePNGDecompressSettings*); 198 199 const void* custom_context; /*optional custom settings for custom functions*/ 200 }; 201 202 extern const LodePNGDecompressSettings lodepng_default_decompress_settings; 203 void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings); 204 #endif /*LODEPNG_COMPILE_DECODER*/ 205 206 #ifdef LODEPNG_COMPILE_ENCODER 207 /* 208 Settings for zlib compression. Tweaking these settings tweaks the balance 209 between speed and compression ratio. 210 */ 211 typedef struct LodePNGCompressSettings LodePNGCompressSettings; 212 struct LodePNGCompressSettings /*deflate = compress*/ 213 { 214 /*LZ77 related settings*/ 215 unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for 216 proper compression.*/ 217 unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ 218 unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. 219 Default value: 2048.*/ 220 unsigned minmatch; /*mininum lz77 length. 3 is normally best, 6 can be better for some PNGs. 221 Default: 0*/ 222 unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. 223 Default: 128*/ 224 unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ 225 226 /*use custom zlib encoder instead of built in one (default: null)*/ 227 unsigned (*custom_zlib)(unsigned char**, size_t*, const unsigned char*, size_t, 228 const LodePNGCompressSettings*); 229 /*use custom deflate encoder instead of built in one (default: null) 230 if custom_zlib is used, custom_deflate is ignored since only the built in 231 zlib function will call custom_deflate*/ 232 unsigned (*custom_deflate)(unsigned char**, size_t*, const unsigned char*, size_t, 233 const LodePNGCompressSettings*); 234 235 const void* custom_context; /*optional custom settings for custom functions*/ 236 }; 237 238 extern const LodePNGCompressSettings lodepng_default_compress_settings; 239 void lodepng_compress_settings_init(LodePNGCompressSettings* settings); 240 #endif /*LODEPNG_COMPILE_ENCODER*/ 241 242 #ifdef LODEPNG_COMPILE_PNG 243 /* 244 Color mode of an image. Contains all information required to decode the pixel 245 bits to RGBA colors. This information is the same as used in the PNG file 246 format, and is used both for PNG and raw image data in LodePNG. 247 */ 248 typedef struct LodePNGColorMode 249 { 250 /*header (IHDR)*/ 251 LodePNGColorType 252 colortype; /*color type, see PNG standard or documentation further in this header file*/ 253 unsigned 254 bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ 255 256 /* 257 palette (PLTE and tRNS) 258 259 Dynamically allocated with the colors of the palette, including alpha. 260 When encoding a PNG, to store your colors in the palette of the LodePNGColorMode, first use 261 lodepng_palette_clear, then for each color use lodepng_palette_add. 262 If you encode an image without alpha with palette, don't forget to put value 255 in each A byte 263 of the palette. 264 265 When decoding, by default you can ignore this palette, since LodePNG already 266 fills the palette colors in the pixels of the raw RGBA output. 267 268 The palette is only supported for color type 3. 269 */ 270 unsigned char* palette; /*palette in RGBARGBA... order. When allocated, must be either 0, or 271 have size 1024*/ 272 size_t palettesize; /*palette size in number of colors (amount of bytes is 4 * palettesize)*/ 273 274 /* 275 transparent color key (tRNS) 276 277 This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 278 16-bit. For greyscale PNGs, r, g and b will all 3 be set to the same. 279 280 When decoding, by default you can ignore this information, since LodePNG sets 281 pixels with this key to transparent already in the raw RGBA output. 282 283 The color key is only supported for color types 0 and 2. 284 */ 285 unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ 286 unsigned key_r; /*red/greyscale component of color key*/ 287 unsigned key_g; /*green component of color key*/ 288 unsigned key_b; /*blue component of color key*/ 289 } LodePNGColorMode; 290 291 /*init, cleanup and copy functions to use with this struct*/ 292 void lodepng_color_mode_init(LodePNGColorMode* info); 293 void lodepng_color_mode_cleanup(LodePNGColorMode* info); 294 /*return value is error code (0 means no error)*/ 295 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source); 296 297 void lodepng_palette_clear(LodePNGColorMode* info); 298 /*add 1 color to the palette*/ 299 unsigned lodepng_palette_add(LodePNGColorMode* info, unsigned char r, unsigned char g, 300 unsigned char b, unsigned char a); 301 302 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ 303 unsigned lodepng_get_bpp(const LodePNGColorMode* info); 304 /*get the amount of color channels used, based on colortype in the struct. 305 If a palette is used, it counts as 1 channel.*/ 306 unsigned lodepng_get_channels(const LodePNGColorMode* info); 307 /*is it a greyscale type? (only colortype 0 or 4)*/ 308 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info); 309 /*has it got an alpha channel? (only colortype 2 or 6)*/ 310 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info); 311 /*has it got a palette? (only colortype 3)*/ 312 unsigned lodepng_is_palette_type(const LodePNGColorMode* info); 313 /*only returns true if there is a palette and there is a value in the palette with alpha < 255. 314 Loops through the palette to check this.*/ 315 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info); 316 /* 317 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG 318 image. Returns true if the image can have translucent or invisible pixels (it still be opaque if it 319 doesn't use such pixels). Returns false if the image can only have opaque pixels. In detail, it 320 returns true only if it's a color type with alpha, or has a palette with non-opaque values, or if 321 "key_defined" is true. 322 */ 323 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info); 324 /*Returns the byte size of a raw image buffer with given width, height and color mode*/ 325 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color); 326 327 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 328 /*The information of a Time chunk in PNG.*/ 329 typedef struct LodePNGTime 330 { 331 unsigned year; /*2 bytes used (0-65535)*/ 332 unsigned month; /*1-12*/ 333 unsigned day; /*1-31*/ 334 unsigned hour; /*0-23*/ 335 unsigned minute; /*0-59*/ 336 unsigned second; /*0-60 (to allow for leap seconds)*/ 337 } LodePNGTime; 338 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 339 340 /*Information about the PNG image, except pixels, width and height.*/ 341 typedef struct LodePNGInfo 342 { 343 /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ 344 unsigned compression_method; /*compression method of the original file. Always 0.*/ 345 unsigned filter_method; /*filter method of the original file*/ 346 unsigned interlace_method; /*interlace method of the original file*/ 347 LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/ 348 349 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 350 /* 351 suggested background color chunk (bKGD) 352 This color uses the same color mode as the PNG (except alpha channel), which can be 1-bit to 353 16-bit. 354 355 For greyscale PNGs, r, g and b will all 3 be set to the same. When encoding 356 the encoder writes the red one. For palette PNGs: When decoding, the RGB value 357 will be stored, not a palette index. But when encoding, specify the index of 358 the palette in background_r, the other two are then ignored. 359 360 The decoder does not use this background color to edit the color of pixels. 361 */ 362 unsigned background_defined; /*is a suggested background color given?*/ 363 unsigned background_r; /*red component of suggested background color*/ 364 unsigned background_g; /*green component of suggested background color*/ 365 unsigned background_b; /*blue component of suggested background color*/ 366 367 /* 368 non-international text chunks (tEXt and zTXt) 369 370 The char** arrays each contain num strings. The actual messages are in 371 text_strings, while text_keys are keywords that give a short description what 372 the actual text represents, e.g. Title, Author, Description, or anything else. 373 374 A keyword is minimum 1 character and maximum 79 characters long. It's 375 discouraged to use a single line length longer than 79 characters for texts. 376 377 Don't allocate these text buffers yourself. Use the init/cleanup functions 378 correctly and use lodepng_add_text and lodepng_clear_text. 379 */ 380 size_t 381 text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/ 382 char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/ 383 char** text_strings; /*the actual text*/ 384 385 /* 386 international text chunks (iTXt) 387 Similar to the non-international text chunks, but with additional strings 388 "langtags" and "transkeys". 389 */ 390 size_t itext_num; /*the amount of international texts in this PNG*/ 391 char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ 392 char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 393 language tag*/ 394 char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/ 395 char** itext_strings; /*the actual international text - UTF-8 string*/ 396 397 /*time chunk (tIME)*/ 398 unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ 399 LodePNGTime time; 400 401 /*phys chunk (pHYs)*/ 402 unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 403 else there is one*/ 404 unsigned phys_x; /*pixels per unit in x direction*/ 405 unsigned phys_y; /*pixels per unit in y direction*/ 406 unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ 407 408 /* 409 unknown chunks 410 There are 3 buffers, one for each position in the PNG where unknown chunks can appear 411 each buffer contains all unknown chunks for that position consecutively 412 The 3 buffers are the unknown chunks between certain critical chunks: 413 0: IHDR-PLTE, 1: PLTE-IDAT, 2: IDAT-IEND 414 Do not allocate or traverse this data yourself. Use the chunk traversing functions declared 415 later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct. 416 */ 417 unsigned char* unknown_chunks_data[3]; 418 size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ 419 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 420 } LodePNGInfo; 421 422 /*init, cleanup and copy functions to use with this struct*/ 423 void lodepng_info_init(LodePNGInfo* info); 424 void lodepng_info_cleanup(LodePNGInfo* info); 425 /*return value is error code (0 means no error)*/ 426 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source); 427 428 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 429 void lodepng_clear_text( 430 LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ 431 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, 432 const char* str); /*push back both texts at once*/ 433 434 void lodepng_clear_itext( 435 LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ 436 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag, 437 const char* transkey, 438 const char* str); /*push back the 4 texts of 1 chunk at once*/ 439 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 440 441 /* 442 Converts raw buffer from one color type to another color type, based on 443 LodePNGColorMode structs to describe the input and output color type. 444 See the reference manual at the end of this header file to see which color conversions are 445 supported. return value = LodePNG error code (0 if all went ok, an error if the conversion isn't 446 supported) The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel of 447 the output color type (lodepng_get_bpp). For < 8 bpp images, there should not be padding bits at the 448 end of scanlines. For 16-bit per channel colors, uses big endian format like PNG does. Return value 449 is LodePNG error code 450 */ 451 unsigned lodepng_convert(unsigned char* out, const unsigned char* in, LodePNGColorMode* mode_out, 452 const LodePNGColorMode* mode_in, unsigned w, unsigned h); 453 454 #ifdef LODEPNG_COMPILE_DECODER 455 /* 456 Settings for the decoder. This contains settings for the PNG and the Zlib 457 decoder, but not the Info settings from the Info structs. 458 */ 459 typedef struct LodePNGDecoderSettings 460 { 461 LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ 462 463 unsigned ignore_crc; /*ignore CRC checksums*/ 464 465 unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ 466 467 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 468 unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the 469 unknown chunks*/ 470 /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png 471 * editor)*/ 472 unsigned remember_unknown_chunks; 473 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 474 } LodePNGDecoderSettings; 475 476 void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); 477 #endif /*LODEPNG_COMPILE_DECODER*/ 478 479 #ifdef LODEPNG_COMPILE_ENCODER 480 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ 481 typedef enum LodePNGFilterStrategy 482 { 483 /*every filter at zero*/ 484 LFS_ZERO, 485 /*Use filter that gives minumum sum, as described in the official PNG filter heuristic.*/ 486 LFS_MINSUM, 487 /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending 488 on the image, this is better or worse than minsum.*/ 489 LFS_ENTROPY, 490 /* 491 Brute-force-search PNG filters by compressing each filter for each scanline. 492 Experimental, very slow, and only rarely gives better compression than MINSUM. 493 */ 494 LFS_BRUTE_FORCE, 495 /*use predefined_filters buffer: you specify the filter type for each scanline*/ 496 LFS_PREDEFINED 497 } LodePNGFilterStrategy; 498 499 /*Gives characteristics about the colors of the image, which helps decide which color model to use 500 for encoding. Used internally by default if "auto_convert" is enabled. Public because it's useful 501 for custom algorithms.*/ 502 typedef struct LodePNGColorProfile 503 { 504 unsigned colored; /*not greyscale*/ 505 unsigned key; /*if true, image is not opaque. Only if true and alpha is false, color key is 506 possible.*/ 507 unsigned short key_r; /*these values are always in 16-bit bitdepth in the profile*/ 508 unsigned short key_g; 509 unsigned short key_b; 510 unsigned alpha; /*alpha channel or alpha palette required*/ 511 unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16.*/ 512 unsigned char 513 palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order*/ 514 unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for greyscale only. 16 if 16-bit 515 per channel required.*/ 516 } LodePNGColorProfile; 517 518 void lodepng_color_profile_init(LodePNGColorProfile* profile); 519 520 /*Get a LodePNGColorProfile of the image.*/ 521 unsigned get_color_profile(LodePNGColorProfile* profile, const unsigned char* image, unsigned w, 522 unsigned h, const LodePNGColorMode* mode_in); 523 /*The function LodePNG uses internally to decide the PNG color with auto_convert. 524 Chooses an optimal color model, e.g. grey if only grey pixels, palette if < 256 colors, ...*/ 525 unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out, const unsigned char* image, 526 unsigned w, unsigned h, const LodePNGColorMode* mode_in); 527 528 /*Settings for the encoder.*/ 529 typedef struct LodePNGEncoderSettings 530 { 531 LodePNGCompressSettings 532 zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ 533 534 unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/ 535 536 /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than 537 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to 538 completely follow the official PNG heuristic, filter_palette_zero must be true and 539 filter_strategy must be LFS_MINSUM*/ 540 unsigned filter_palette_zero; 541 /*Which filter strategy to use when not using zeroes due to filter_palette_zero. 542 Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/ 543 LodePNGFilterStrategy filter_strategy; 544 /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with 545 the same length as the amount of scanlines in the image, and each value must <= 5. You 546 have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero 547 must be set to 0 to ensure this is also used on palette or low bitdepth images.*/ 548 const unsigned char* predefined_filters; 549 550 /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). 551 If colortype is 3, PLTE is _always_ created.*/ 552 unsigned force_palette; 553 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 554 /*add LodePNG identifier and version as a text chunk, for debugging*/ 555 unsigned add_id; 556 /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ 557 unsigned text_compression; 558 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 559 } LodePNGEncoderSettings; 560 561 void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); 562 #endif /*LODEPNG_COMPILE_ENCODER*/ 563 564 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) 565 /*The settings, state and information for extended encoding and decoding.*/ 566 typedef struct LodePNGState 567 { 568 #ifdef LODEPNG_COMPILE_DECODER 569 LodePNGDecoderSettings decoder; /*the decoding settings*/ 570 #endif /*LODEPNG_COMPILE_DECODER*/ 571 #ifdef LODEPNG_COMPILE_ENCODER 572 LodePNGEncoderSettings encoder; /*the encoding settings*/ 573 #endif /*LODEPNG_COMPILE_ENCODER*/ 574 LodePNGColorMode 575 info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ 576 LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/ 577 unsigned error; 578 } LodePNGState; 579 580 /*init, cleanup and copy functions to use with this struct*/ 581 void lodepng_state_init(LodePNGState* state); 582 void lodepng_state_cleanup(LodePNGState* state); 583 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source); 584 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */ 585 586 #ifdef LODEPNG_COMPILE_DECODER 587 /* 588 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and 589 getting much more information about the PNG image and color mode. 590 */ 591 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, LodePNGState* state, 592 const unsigned char* in, size_t insize); 593 594 /* 595 Read the PNG header, but not the actual data. This returns only the information 596 that is in the header chunk of the PNG, such as width, height and color type. The 597 information is placed in the info_png field of the LodePNGState. 598 */ 599 unsigned lodepng_inspect(unsigned* w, unsigned* h, LodePNGState* state, const unsigned char* in, 600 size_t insize); 601 #endif /*LODEPNG_COMPILE_DECODER*/ 602 603 #ifdef LODEPNG_COMPILE_ENCODER 604 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ 605 unsigned lodepng_encode(unsigned char** out, size_t* outsize, const unsigned char* image, 606 unsigned w, unsigned h, LodePNGState* state); 607 #endif /*LODEPNG_COMPILE_ENCODER*/ 608 609 /* 610 The lodepng_chunk functions are normally not needed, except to traverse the 611 unknown chunks stored in the LodePNGInfo struct, or add new ones to it. 612 It also allows traversing the chunks of an encoded PNG file yourself. 613 614 PNG standard chunk naming conventions: 615 First byte: uppercase = critical, lowercase = ancillary 616 Second byte: uppercase = public, lowercase = private 617 Third byte: must be uppercase 618 Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy 619 */ 620 621 /*get the length of the data of the chunk. Total chunk length has 12 bytes more.*/ 622 unsigned lodepng_chunk_length(const unsigned char* chunk); 623 624 /*puts the 4-byte type in null terminated string*/ 625 void lodepng_chunk_type(char type[5], const unsigned char* chunk); 626 627 /*check if the type is the given type*/ 628 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type); 629 630 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ 631 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk); 632 633 /*0: public, 1: private (see PNG standard)*/ 634 unsigned char lodepng_chunk_private(const unsigned char* chunk); 635 636 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ 637 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk); 638 639 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/ 640 unsigned char* lodepng_chunk_data(unsigned char* chunk); 641 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk); 642 643 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ 644 unsigned lodepng_chunk_check_crc(const unsigned char* chunk); 645 646 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ 647 void lodepng_chunk_generate_crc(unsigned char* chunk); 648 649 /*iterate to next chunks. don't use on IEND chunk, as there is no next chunk then*/ 650 unsigned char* lodepng_chunk_next(unsigned char* chunk); 651 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk); 652 653 /* 654 Appends chunk to the data in out. The given chunk should already have its chunk header. 655 The out variable and outlength are updated to reflect the new reallocated buffer. 656 Returns error code (0 if it went ok) 657 */ 658 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk); 659 660 /* 661 Appends new chunk to out. The chunk to append is given by giving its length, type 662 and data separately. The type is a 4-letter string. 663 The out variable and outlength are updated to reflect the new reallocated buffer. 664 Returne error code (0 if it went ok) 665 */ 666 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 667 const char* type, const unsigned char* data); 668 669 /*Calculate CRC32 of buffer*/ 670 unsigned lodepng_crc32(const unsigned char* buf, size_t len); 671 #endif /*LODEPNG_COMPILE_PNG*/ 672 673 #ifdef LODEPNG_COMPILE_ZLIB 674 /* 675 This zlib part can be used independently to zlib compress and decompress a 676 buffer. It cannot be used to create gzip files however, and it only supports the 677 part of zlib that is required for PNG, it does not support dictionaries. 678 */ 679 680 #ifdef LODEPNG_COMPILE_DECODER 681 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after 682 * use.*/ 683 unsigned lodepng_inflate(unsigned char** out, size_t* outsize, const unsigned char* in, 684 size_t insize, const LodePNGDecompressSettings* settings); 685 686 /* 687 Decompresses Zlib data. Reallocates the out buffer and appends the data. The 688 data must be according to the zlib specification. 689 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 690 buffer and *outsize its size in bytes. out must be freed by user after usage. 691 */ 692 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, const unsigned char* in, 693 size_t insize, const LodePNGDecompressSettings* settings); 694 #endif /*LODEPNG_COMPILE_DECODER*/ 695 696 #ifdef LODEPNG_COMPILE_ENCODER 697 /* 698 Compresses data with Zlib. Reallocates the out buffer and appends the data. 699 Zlib adds a small header and trailer around the deflate data. 700 The data is output in the format of the zlib specification. 701 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 702 buffer and *outsize its size in bytes. out must be freed by user after usage. 703 */ 704 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, const unsigned char* in, 705 size_t insize, const LodePNGCompressSettings* settings); 706 707 /* 708 Find length-limited Huffman code for given frequencies. This function is in the 709 public interface only for tests, it's used internally by lodepng_deflate. 710 */ 711 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies, 712 size_t numcodes, unsigned maxbitlen); 713 714 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ 715 unsigned lodepng_deflate(unsigned char** out, size_t* outsize, const unsigned char* in, 716 size_t insize, const LodePNGCompressSettings* settings); 717 718 #endif /*LODEPNG_COMPILE_ENCODER*/ 719 #endif /*LODEPNG_COMPILE_ZLIB*/ 720 721 #ifdef LODEPNG_COMPILE_DISK 722 /* 723 Load a file from disk into buffer. The function allocates the out buffer, and 724 after usage you should free it. 725 out: output parameter, contains pointer to loaded buffer. 726 outsize: output parameter, size of the allocated out buffer 727 filename: the path to the file to load 728 return value: error code (0 means ok) 729 */ 730 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename); 731 732 /* 733 Save a file from buffer to disk. Warning, if it exists, this function overwrites 734 the file without warning! 735 buffer: the buffer to write 736 buffersize: size of the buffer to write 737 filename: the path to the file to save to 738 return value: error code (0 means ok) 739 */ 740 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename); 741 #endif /*LODEPNG_COMPILE_DISK*/ 742 743 /* 744 TODO: 745 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked 746 often 747 [.] check compatibility with vareous compilers - done but needs to be redone for every newer 748 version [X] converting color to 16-bit per channel types [ ] read all public PNG chunk types (but 749 never let the color profile and gamma ones touch RGB values) [ ] make sure encoder generates no 750 chunks with size > (2^31)-1 [ ] partial decoding (stream processing) [X] let the "isFullyOpaque" 751 function check color keys and transparent palettes too [X] better name for the variables "codes", 752 "codesD", "codelengthcodes", "clcl" and "lldl" [ ] don't stop decoding on errors like 69, 57, 58 753 (make warnings) [ ] make option to choose if the raw image with non multiple of 8 bits per scanline 754 should have padding bits or not [ ] let the C++ wrapper catch exceptions coming from the standard 755 library and return LodePNG error codes 756 */ 757 758 #endif /*LODEPNG_H inclusion guard*/ 759 760 /* 761 LodePNG Documentation 762 --------------------- 763 764 0. table of contents 765 -------------------- 766 767 1. about 768 1.1. supported features 769 1.2. features not supported 770 2. C and C++ version 771 3. security 772 4. decoding 773 5. encoding 774 6. color conversions 775 6.1. PNG color types 776 6.2. color conversions 777 6.3. padding bits 778 6.4. A note about 16-bits per channel and endianness 779 7. error values 780 8. chunks and PNG editing 781 9. compiler support 782 10. examples 783 10.1. decoder C++ example 784 10.2. decoder C example 785 11. changes 786 12. contact information 787 788 789 1. about 790 -------- 791 792 PNG is a file format to store raster images losslessly with good compression, 793 supporting different color types and alpha channel. 794 795 LodePNG is a PNG codec according to the Portable Network Graphics (PNG) 796 Specification (Second Edition) - W3C Recommendation 10 November 2003. 797 798 The specifications used are: 799 800 *) Portable Network Graphics (PNG) Specification (Second Edition): 801 http://www.w3.org/TR/2003/REC-PNG-20031110 802 *) RFC 1950 ZLIB Compressed Data Format version 3.3: 803 http://www.gzip.org/zlib/rfc-zlib.html 804 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3: 805 http://www.gzip.org/zlib/rfc-deflate.html 806 807 The most recent version of LodePNG can currently be found at 808 http://lodev.org/lodepng/ 809 810 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds 811 extra functionality. 812 813 LodePNG exists out of two files: 814 -lodepng.h: the header file for both C and C++ 815 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage 816 817 If you want to start using LodePNG right away without reading this doc, get the 818 examples from the LodePNG website to see how to use it in code, or check the 819 smaller examples in chapter 13 here. 820 821 LodePNG is simple but only supports the basic requirements. To achieve 822 simplicity, the following design choices were made: There are no dependencies 823 on any external library. There are functions to decode and encode a PNG with 824 a single function call, and extended versions of these functions taking a 825 LodePNGState struct allowing to specify or get more information. By default 826 the colors of the raw image are always RGB or RGBA, no matter what color type 827 the PNG file uses. To read and write files, there are simple functions to 828 convert the files to/from buffers in memory. 829 830 This all makes LodePNG suitable for loading textures in games, demos and small 831 programs, ... It's less suitable for full fledged image editors, loading PNGs 832 over network (it requires all the image data to be available before decoding can 833 begin), life-critical systems, ... 834 835 1.1. supported features 836 ----------------------- 837 838 The following features are supported by the decoder: 839 840 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw 841 image, or the same color type as the PNG 842 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw 843 image 844 *) Adam7 interlace and deinterlace for any color type 845 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk 846 *) support for alpha channels, including RGBA color model, translucent palettes and color keying 847 *) zlib decompression (inflate) 848 *) zlib compression (deflate) 849 *) CRC32 and ADLER32 checksums 850 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks. 851 *) the following chunks are supported (generated/interpreted) by both encoder and decoder: 852 IHDR: header information 853 PLTE: color palette 854 IDAT: pixel data 855 IEND: the final chunk 856 tRNS: transparency for palettized images 857 tEXt: textual information 858 zTXt: compressed textual information 859 iTXt: international textual information 860 bKGD: suggested background color 861 pHYs: physical dimensions 862 tIME: modification time 863 864 1.2. features not supported 865 --------------------------- 866 867 The following features are _not_ supported: 868 869 *) some features needed to make a conformant PNG-Editor might be still missing. 870 *) partial loading/stream processing. All data must be available and is processed in one call. 871 *) The following public chunks are not supported but treated as unknown chunks by LodePNG 872 cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT 873 Some of these are not supported on purpose: LodePNG wants to provide the RGB values 874 stored in the pixels, not values modified by system dependent gamma or color models. 875 876 877 2. C and C++ version 878 -------------------- 879 880 The C version uses buffers allocated with alloc that you need to free() 881 yourself. You need to use init and cleanup functions for each struct whenever 882 using a struct from the C version to avoid exploits and memory leaks. 883 884 The C++ version has extra functions with std::vectors in the interface and the 885 lodepng::State class which is a LodePNGState with constructor and destructor. 886 887 These files work without modification for both C and C++ compilers because all 888 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers 889 ignore it, and the C code is made to compile both with strict ISO C90 and C++. 890 891 To use the C++ version, you need to rename the source file to lodepng.cpp 892 (instead of lodepng.c), and compile it with a C++ compiler. 893 894 To use the C version, you need to rename the source file to lodepng.c (instead 895 of lodepng.cpp), and compile it with a C compiler. 896 897 898 3. Security 899 ----------- 900 901 Even if carefully designed, it's always possible that LodePNG contains possible 902 exploits. If you discover one, please let me know, and it will be fixed. 903 904 When using LodePNG, care has to be taken with the C version of LodePNG, as well 905 as the C-style structs when working with C++. The following conventions are used 906 for all C-style structs: 907 908 -if a struct has a corresponding init function, always call the init function when making a new one 909 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid 910 memory leaks -if a struct has a corresponding copy function, use the copy function instead of "=". 911 The destination must also be inited already. 912 913 914 4. Decoding 915 ----------- 916 917 Decoding converts a PNG compressed image to a raw pixel buffer. 918 919 Most documentation on using the decoder is at its declarations in the header 920 above. For C, simple decoding can be done with functions such as 921 lodepng_decode32, and more advanced decoding can be done with the struct 922 LodePNGState and lodepng_decode. For C++, all decoding can be done with the 923 various lodepng::decode functions, and lodepng::State can be used for advanced 924 features. 925 926 When using the LodePNGState, it uses the following fields for decoding: 927 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here 928 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you 929 want to get 930 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use 931 932 LodePNGInfo info_png 933 -------------------- 934 935 After decoding, this contains extra information of the PNG image, except the actual 936 pixels, width and height because these are already gotten directly from the decoder 937 functions. 938 939 It contains for example the original color type of the PNG image, text comments, 940 suggested background color, etc... More details about the LodePNGInfo struct are 941 at its declaration documentation. 942 943 LodePNGColorMode info_raw 944 ------------------------- 945 946 When decoding, here you can specify which color type you want 947 the resulting raw image to be. If this is different from the colortype of the 948 PNG, then the decoder will automatically convert the result. This conversion 949 always works, except if you want it to convert a color PNG to greyscale or to 950 a palette with missing colors. 951 952 By default, 32-bit color is used for the result. 953 954 LodePNGDecoderSettings decoder 955 ------------------------------ 956 957 The settings can be used to ignore the errors created by invalid CRC and Adler32 958 chunks, and to disable the decoding of tEXt chunks. 959 960 There's also a setting color_convert, true by default. If false, no conversion 961 is done, the resulting data will be as it was in the PNG (after decompression) 962 and you'll have to puzzle the colors of the pixels together yourself using the 963 color type information in the LodePNGInfo. 964 965 966 5. Encoding 967 ----------- 968 969 Encoding converts a raw pixel buffer to a PNG compressed image. 970 971 Most documentation on using the encoder is at its declarations in the header 972 above. For C, simple encoding can be done with functions such as 973 lodepng_encode32, and more advanced decoding can be done with the struct 974 LodePNGState and lodepng_encode. For C++, all encoding can be done with the 975 various lodepng::encode functions, and lodepng::State can be used for advanced 976 features. 977 978 Like the decoder, the encoder can also give errors. However it gives less errors 979 since the encoder input is trusted, the decoder input (a PNG image that could 980 be forged by anyone) is not trusted. 981 982 When using the LodePNGState, it uses the following fields for encoding: 983 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be. 984 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has 985 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use 986 987 LodePNGInfo info_png 988 -------------------- 989 990 When encoding, you use this the opposite way as when decoding: for encoding, 991 you fill in the values you want the PNG to have before encoding. By default it's 992 not needed to specify a color type for the PNG since it's automatically chosen, 993 but it's possible to choose it yourself given the right settings. 994 995 The encoder will not always exactly match the LodePNGInfo struct you give, 996 it tries as close as possible. Some things are ignored by the encoder. The 997 encoder uses, for example, the following settings from it when applicable: 998 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the 999 background color, the interlace method, unknown chunks, ... 1000 1001 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk. 1002 If the palette contains any colors for which the alpha channel is not 255 (so 1003 there are translucent colors in the palette), it'll add a tRNS chunk. 1004 1005 LodePNGColorMode info_raw 1006 ------------------------- 1007 1008 You specify the color type of the raw image that you give to the input here, 1009 including a possible transparent color key and palette you happen to be using in 1010 your raw image data. 1011 1012 By default, 32-bit color is assumed, meaning your input has to be in RGBA 1013 format with 4 bytes (unsigned chars) per pixel. 1014 1015 LodePNGEncoderSettings encoder 1016 ------------------------------ 1017 1018 The following settings are supported (some are in sub-structs): 1019 *) auto_convert: when this option is enabled, the encoder will 1020 automatically choose the smallest possible color mode (including color key) that 1021 can encode the colors of all pixels without information loss. 1022 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree, 1023 2 = dynamic huffman tree (best compression). Should be 2 for proper 1024 compression. 1025 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be 1026 true for proper compression. 1027 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value 1028 2048 by default, but can be set to 32768 for better, but slow, compression. 1029 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE 1030 chunk if force_palette is true. This can used as suggested palette to convert 1031 to by viewers that don't support more than 256 colors (if those still exist) 1032 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image. 1033 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks. 1034 zTXt chunks use zlib compression on the text. This gives a smaller result on 1035 large texts but a larger result on small texts (such as a single program name). 1036 It's all tEXt or all zTXt though, there's no separate setting per text yet. 1037 1038 1039 6. color conversions 1040 -------------------- 1041 1042 An important thing to note about LodePNG, is that the color type of the PNG, and 1043 the color type of the raw image, are completely independent. By default, when 1044 you decode a PNG, you get the result as a raw image in the color type you want, 1045 no matter whether the PNG was encoded with a palette, greyscale or RGBA color. 1046 And if you encode an image, by default LodePNG will automatically choose the PNG 1047 color type that gives good compression based on the values of colors and amount 1048 of colors in the image. It can be configured to let you control it instead as 1049 well, though. 1050 1051 To be able to do this, LodePNG does conversions from one color mode to another. 1052 It can convert from almost any color type to any other color type, except the 1053 following conversions: RGB to greyscale is not supported, and converting to a 1054 palette when the palette doesn't have a required color is not supported. This is 1055 not supported on purpose: this is information loss which requires a color 1056 reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to grey 1057 is easy, but there are multiple ways if you want to give some channels more 1058 weight). 1059 1060 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB 1061 color, no matter what color type the PNG has. And by default when encoding, 1062 LodePNG automatically picks the best color model for the output PNG, and expects 1063 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control 1064 the color format of the images yourself, you can skip this chapter. 1065 1066 6.1. PNG color types 1067 -------------------- 1068 1069 A PNG image can have many color types, ranging from 1-bit color to 64-bit color, 1070 as well as palettized color modes. After the zlib decompression and unfiltering 1071 in the PNG image is done, the raw pixel data will have that color type and thus 1072 a certain amount of bits per pixel. If you want the output raw image after 1073 decoding to have another color type, a conversion is done by LodePNG. 1074 1075 The PNG specification gives the following color types: 1076 1077 0: greyscale, bit depths 1, 2, 4, 8, 16 1078 2: RGB, bit depths 8 and 16 1079 3: palette, bit depths 1, 2, 4 and 8 1080 4: greyscale with alpha, bit depths 8 and 16 1081 6: RGBA, bit depths 8 and 16 1082 1083 Bit depth is the amount of bits per pixel per color channel. So the total amount 1084 of bits per pixel is: amount of channels * bitdepth. 1085 1086 6.2. color conversions 1087 ---------------------- 1088 1089 As explained in the sections about the encoder and decoder, you can specify 1090 color types and bit depths in info_png and info_raw to change the default 1091 behaviour. 1092 1093 If, when decoding, you want the raw image to be something else than the default, 1094 you need to set the color type and bit depth you want in the LodePNGColorMode, 1095 or the parameters colortype and bitdepth of the simple decoding function. 1096 1097 If, when encoding, you use another color type than the default in the raw input 1098 image, you need to specify its color type and bit depth in the LodePNGColorMode 1099 of the raw image, or use the parameters colortype and bitdepth of the simple 1100 encoding function. 1101 1102 If, when encoding, you don't want LodePNG to choose the output PNG color type 1103 but control it yourself, you need to set auto_convert in the encoder settings 1104 to false, and specify the color type you want in the LodePNGInfo of the 1105 encoder (including palette: it can generate a palette if auto_convert is true, 1106 otherwise not). 1107 1108 If the input and output color type differ (whether user chosen or auto chosen), 1109 LodePNG will do a color conversion, which follows the rules below, and may 1110 sometimes result in an error. 1111 1112 To avoid some confusion: 1113 -the decoder converts from PNG to raw image 1114 -the encoder converts from raw image to PNG 1115 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image 1116 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG 1117 -when encoding, the color type in LodePNGInfo is ignored if auto_convert 1118 is enabled, it is automatically generated instead 1119 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original 1120 PNG image, but it can be ignored since the raw image has the color type you requested instead 1121 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion 1122 between the color types is done if the color types are supported. If it is not 1123 supported, an error is returned. If the types are the same, no conversion is done. 1124 -even though some conversions aren't supported, LodePNG supports loading PNGs from any 1125 colortype and saving PNGs to any colortype, sometimes it just requires preparing 1126 the raw image correctly before encoding. 1127 -both encoder and decoder use the same color converter. 1128 1129 Non supported color conversions: 1130 -color to greyscale: no error is thrown, but the result will look ugly because 1131 only the red channel is taken 1132 -anything to palette when that palette does not have that color in it: in this 1133 case an error is thrown 1134 1135 Supported color conversions: 1136 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA 1137 -any grey or grey+alpha, to grey or grey+alpha 1138 -anything to a palette, as long as the palette has the requested colors in it 1139 -removing alpha channel 1140 -higher to smaller bitdepth, and vice versa 1141 1142 If you want no color conversion to be done (e.g. for speed or control): 1143 -In the encoder, you can make it save a PNG with any color type by giving the 1144 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to 1145 false. 1146 -In the decoder, you can make it store the pixel data in the same color type 1147 as the PNG has, by setting the color_convert setting to false. Settings in 1148 info_raw are then ignored. 1149 1150 The function lodepng_convert does the color conversion. It is available in the 1151 interface but normally isn't needed since the encoder and decoder already call 1152 it. 1153 1154 6.3. padding bits 1155 ----------------- 1156 1157 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines 1158 have a bit amount that isn't a multiple of 8, then padding bits are used so that each 1159 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output. 1160 The raw input image you give to the encoder, and the raw output image you get from the decoder 1161 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width 1162 of 7 pixels, the first pixel of the second scanline will the the 8th bit of the first byte, 1163 not the first bit of a new byte. 1164 1165 6.4. A note about 16-bits per channel and endianness 1166 ---------------------------------------------------- 1167 1168 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like 1169 for any other color format. The 16-bit values are stored in big endian (most 1170 significant byte first) in these arrays. This is the opposite order of the 1171 little endian used by x86 CPU's. 1172 1173 LodePNG always uses big endian because the PNG file format does so internally. 1174 Conversions to other formats than PNG uses internally are not supported by 1175 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit 1176 colors, the order in which you store R, G, B and A, and so on. Supporting and 1177 converting to/from all that is outside the scope of LodePNG. 1178 1179 This may mean that, depending on your use case, you may want to convert the big 1180 endian output of LodePNG to little endian with a for loop. This is certainly not 1181 always needed, many applications and libraries support big endian 16-bit colors 1182 anyway, but it means you cannot simply cast the unsigned char* buffer to an 1183 unsigned short* buffer on x86 CPUs. 1184 1185 1186 7. error values 1187 --------------- 1188 1189 All functions in LodePNG that return an error code, return 0 if everything went 1190 OK, or a non-zero code if there was an error. 1191 1192 The meaning of the LodePNG error values can be retrieved with the function 1193 lodepng_error_text: given the numerical error code, it returns a description 1194 of the error in English as a string. 1195 1196 Check the implementation of lodepng_error_text to see the meaning of each code. 1197 1198 1199 8. chunks and PNG editing 1200 ------------------------- 1201 1202 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG 1203 editor that should follow the rules about handling of unknown chunks, or if your 1204 program is able to read other types of chunks than the ones handled by LodePNG, 1205 then that's possible with the chunk functions of LodePNG. 1206 1207 A PNG chunk has the following layout: 1208 1209 4 bytes length 1210 4 bytes type name 1211 length bytes data 1212 4 bytes CRC 1213 1214 8.1. iterating through chunks 1215 ----------------------------- 1216 1217 If you have a buffer containing the PNG image data, then the first chunk (the 1218 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the 1219 signature of the PNG and are not part of a chunk. But if you start at byte 8 1220 then you have a chunk, and can check the following things of it. 1221 1222 NOTE: none of these functions check for memory buffer boundaries. To avoid 1223 exploits, always make sure the buffer contains all the data of the chunks. 1224 When using lodepng_chunk_next, make sure the returned value is within the 1225 allocated memory. 1226 1227 unsigned lodepng_chunk_length(const unsigned char* chunk): 1228 1229 Get the length of the chunk's data. The total chunk length is this length + 12. 1230 1231 void lodepng_chunk_type(char type[5], const unsigned char* chunk): 1232 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type): 1233 1234 Get the type of the chunk or compare if it's a certain type 1235 1236 unsigned char lodepng_chunk_critical(const unsigned char* chunk): 1237 unsigned char lodepng_chunk_private(const unsigned char* chunk): 1238 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk): 1239 1240 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are). 1241 Check if the chunk is private (public chunks are part of the standard, private ones not). 1242 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical 1243 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your 1244 program doesn't handle that type of unknown chunk. 1245 1246 unsigned char* lodepng_chunk_data(unsigned char* chunk): 1247 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk): 1248 1249 Get a pointer to the start of the data of the chunk. 1250 1251 unsigned lodepng_chunk_check_crc(const unsigned char* chunk): 1252 void lodepng_chunk_generate_crc(unsigned char* chunk): 1253 1254 Check if the crc is correct or generate a correct one. 1255 1256 unsigned char* lodepng_chunk_next(unsigned char* chunk): 1257 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk): 1258 1259 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these 1260 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough 1261 data available in the buffer to be able to go to the next chunk. 1262 1263 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk): 1264 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 1265 const char* type, const unsigned char* data): 1266 1267 These functions are used to create new chunks that are appended to the data in *out that has 1268 length *outlength. The append function appends an existing chunk to the new data. The create 1269 function creates a new chunk with the given parameters and appends it. Type is the 4-letter 1270 name of the chunk. 1271 1272 8.2. chunks in info_png 1273 ----------------------- 1274 1275 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3 1276 buffers (each with size) to contain 3 types of unknown chunks: 1277 the ones that come before the PLTE chunk, the ones that come between the PLTE 1278 and the IDAT chunks, and the ones that come after the IDAT chunks. 1279 It's necessary to make the distionction between these 3 cases because the PNG 1280 standard forces to keep the ordering of unknown chunks compared to the critical 1281 chunks, but does not force any other ordering rules. 1282 1283 info_png.unknown_chunks_data[0] is the chunks before PLTE 1284 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT 1285 info_png.unknown_chunks_data[2] is the chunks after IDAT 1286 1287 The chunks in these 3 buffers can be iterated through and read by using the same 1288 way described in the previous subchapter. 1289 1290 When using the decoder to decode a PNG, you can make it store all unknown chunks 1291 if you set the option settings.remember_unknown_chunks to 1. By default, this 1292 option is off (0). 1293 1294 The encoder will always encode unknown chunks that are stored in the info_png. 1295 If you need it to add a particular chunk that isn't known by LodePNG, you can 1296 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in 1297 info_png.unknown_chunks_data[x]. 1298 1299 Chunks that are known by LodePNG should not be added in that way. E.g. to make 1300 LodePNG add a bKGD chunk, set background_defined to true and add the correct 1301 parameters there instead. 1302 1303 1304 9. compiler support 1305 ------------------- 1306 1307 No libraries other than the current standard C library are needed to compile 1308 LodePNG. For the C++ version, only the standard C++ library is needed on top. 1309 Add the files lodepng.c(pp) and lodepng.h to your project, include 1310 lodepng.h where needed, and your program can read/write PNG files. 1311 1312 It is compatible with C90 and up, and C++03 and up. 1313 1314 If performance is important, use optimization when compiling! For both the 1315 encoder and decoder, this makes a large difference. 1316 1317 Make sure that LodePNG is compiled with the same compiler of the same version 1318 and with the same settings as the rest of the program, or the interfaces with 1319 std::vectors and std::strings in C++ can be incompatible. 1320 1321 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets. 1322 1323 *) gcc and g++ 1324 1325 LodePNG is developed in gcc so this compiler is natively supported. It gives no 1326 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++ 1327 version 4.7.1 on Linux, 32-bit and 64-bit. 1328 1329 *) Clang 1330 1331 Fully supported and warning-free. 1332 1333 *) Mingw 1334 1335 The Mingw compiler (a port of gcc for Windows) should be fully supported by 1336 LodePNG. 1337 1338 *) Visual Studio and Visual C++ Express Edition 1339 1340 LodePNG should be warning-free with warning level W4. Two warnings were disabled 1341 with pragmas though: warning 4244 about implicit conversions, and warning 4996 1342 where it wants to use a non-standard function fopen_s instead of the standard C 1343 fopen. 1344 1345 Visual Studio may want "stdafx.h" files to be included in each source file and 1346 give an error "unexpected end of file while looking for precompiled header". 1347 This is not standard C++ and will not be added to the stock LodePNG. You can 1348 disable it for lodepng.cpp only by right clicking it, Properties, C/C++, 1349 Precompiled Headers, and set it to Not Using Precompiled Headers there. 1350 1351 NOTE: Modern versions of VS should be fully supported, but old versions, e.g. 1352 VS6, are not guaranteed to work. 1353 1354 *) Compilers on Macintosh 1355 1356 LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for 1357 C and C++. 1358 1359 *) Other Compilers 1360 1361 If you encounter problems on any compilers, feel free to let me know and I may 1362 try to fix it if the compiler is modern and standards complient. 1363 1364 1365 10. examples 1366 ------------ 1367 1368 This decoder example shows the most basic usage of LodePNG. More complex 1369 examples can be found on the LodePNG website. 1370 1371 10.1. decoder C++ example 1372 ------------------------- 1373 1374 #include "lodepng.h" 1375 #include <iostream> 1376 1377 int main(int argc, char *argv[]) 1378 { 1379 const char* filename = argc > 1 ? argv[1] : "test.png"; 1380 1381 //load and decode 1382 std::vector<unsigned char> image; 1383 unsigned width, height; 1384 unsigned error = lodepng::decode(image, width, height, filename); 1385 1386 //if there's an error, display it 1387 if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << 1388 std::endl; 1389 1390 //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as 1391 texture, draw it, ... 1392 } 1393 1394 10.2. decoder C example 1395 ----------------------- 1396 1397 #include "lodepng.h" 1398 1399 int main(int argc, char *argv[]) 1400 { 1401 unsigned error; 1402 unsigned char* image; 1403 size_t width, height; 1404 const char* filename = argc > 1 ? argv[1] : "test.png"; 1405 1406 error = lodepng_decode32_file(&image, &width, &height, filename); 1407 1408 if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error)); 1409 1410 / * use image here * / 1411 1412 free(image); 1413 return 0; 1414 } 1415 1416 1417 11. changes 1418 ----------- 1419 1420 The version number of LodePNG is the date of the change given in the format 1421 yyyymmdd. 1422 1423 Some changes aren't backwards compatible. Those are indicated with a (!) 1424 symbol. 1425 1426 *) 23 aug 2014: Reduced needless memory usage of decoder. 1427 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for 1428 simplicity. Made ColorProfile public. 1429 *) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization. 1430 *) 22 dec 2013: Power of two windowsize required for optimization. 1431 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key. 1432 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png). 1433 *) 11 mar 2013 (!): Bugfix with custom free. Changed from "my" to "lodepng_" 1434 prefix for the custom allocators and made it possible with a new #define to 1435 use custom ones in your project without needing to change lodepng's code. 1436 *) 28 jan 2013: Bugfix with color key. 1437 *) 27 okt 2012: Tweaks in text chunk keyword length error handling. 1438 *) 8 okt 2012 (!): Added new filter strategy (entropy) and new auto color mode. 1439 (no palette). Better deflate tree encoding. New compression tweak settings. 1440 Faster color conversions while decoding. Some internal cleanups. 1441 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit. 1442 *) 1 sep 2012 (!): Removed #define's for giving custom (de)compression functions 1443 and made it work with function pointers instead. 1444 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc 1445 and free functions and toggle #defines from compiler flags. Small fixes. 1446 *) 6 may 2012 (!): Made plugging in custom zlib/deflate functions more flexible. 1447 *) 22 apr 2012 (!): Made interface more consistent, renaming a lot. Removed 1448 redundant C++ codec classes. Reduced amount of structs. Everything changed, 1449 but it is cleaner now imho and functionality remains the same. Also fixed 1450 several bugs and shrinked the implementation code. Made new samples. 1451 *) 6 nov 2011 (!): By default, the encoder now automatically chooses the best 1452 PNG color model and bit depth, based on the amount and type of colors of the 1453 raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color. 1454 *) 9 okt 2011: simpler hash chain implementation for the encoder. 1455 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching. 1456 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking. 1457 A bug with the PNG filtertype heuristic was fixed, so that it chooses much 1458 better ones (it's quite significant). A setting to do an experimental, slow, 1459 brute force search for PNG filter types is added. 1460 *) 17 aug 2011 (!): changed some C zlib related function names. 1461 *) 16 aug 2011: made the code less wide (max 120 characters per line). 1462 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors. 1463 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled. 1464 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman 1465 to optimize long sequences of zeros. 1466 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and 1467 LodePNG_InfoColor_canHaveAlpha functions for convenience. 1468 *) 7 nov 2010: added LodePNG_error_text function to get error code description. 1469 *) 30 okt 2010: made decoding slightly faster 1470 *) 26 okt 2010: (!) changed some C function and struct names (more consistent). 1471 Reorganized the documentation and the declaration order in the header. 1472 *) 08 aug 2010: only changed some comments and external samples. 1473 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version. 1474 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers. 1475 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could 1476 read by ignoring the problem but windows apps couldn't. 1477 *) 06 jun 2008: added more error checks for out of memory cases. 1478 *) 26 apr 2008: added a few more checks here and there to ensure more safety. 1479 *) 06 mar 2008: crash with encoding of strings fixed 1480 *) 02 feb 2008: support for international text chunks added (iTXt) 1481 *) 23 jan 2008: small cleanups, and #defines to divide code in sections 1482 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor. 1483 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder. 1484 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added 1485 Also vareous fixes, such as in the deflate and the padding bits code. 1486 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved 1487 filtering code of encoder. 1488 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A 1489 C++ wrapper around this provides an interface almost identical to before. 1490 Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code 1491 are together in these files but it works both for C and C++ compilers. 1492 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks 1493 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible 1494 *) 09 aug 2007: some VS2005 warnings removed again 1495 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code 1496 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images 1497 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing 1498 invalid std::vector element [0] fixed, and level 3 and 4 warnings removed 1499 *) 02 jun 2007: made the encoder add a tag with version by default 1500 *) 27 may 2007: zlib and png code separated (but still in the same file), 1501 simple encoder/decoder functions added for more simple usage cases 1502 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69), 1503 moved some examples from here to lodepng_examples.cpp 1504 *) 12 may 2007: palette decoding bug fixed 1505 *) 24 apr 2007: changed the license from BSD to the zlib license 1506 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks. 1507 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding 1508 palettized PNG images. Plus little interface change with palette and texts. 1509 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes. 1510 Fixed a bug where the end code of a block had length 0 in the Huffman tree. 1511 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented 1512 and supported by the encoder, resulting in smaller PNGs at the output. 1513 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone. 1514 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any 1515 greyscale type to 8-bit greyscale with or without alpha. 1516 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types 1517 to convert to and is more uniform. See the manual for how it works now. 1518 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days: 1519 encode/decode custom tEXt chunks, separate classes for zlib & deflate, and 1520 at last made the decoder give errors for incorrect Adler32 or Crc. 1521 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel. 1522 *) 29 dec 2006: Added support for encoding images without alpha channel, and 1523 cleaned out code as well as making certain parts faster. 1524 *) 28 dec 2006: Added "Settings" to the encoder. 1525 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now. 1526 Removed some code duplication in the decoder. Fixed little bug in an example. 1527 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter. 1528 Fixed a bug of the decoder with 16-bit per color. 1529 *) 15 okt 2006: Changed documentation structure 1530 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the 1531 given image buffer, however for now it's not compressed. 1532 *) 08 sep 2006: (!) Changed to interface with a Decoder class 1533 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different 1534 way. Renamed decodePNG to decodePNGGeneric. 1535 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a 1536 struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy. 1537 *) 28 jul 2006: Cleaned the code and added new error checks. 1538 Corrected terminology "deflate" into "inflate". 1539 *) 23 jun 2006: Added SDL example in the documentation in the header, this 1540 example allows easy debugging by displaying the PNG and its transparency. 1541 *) 22 jun 2006: (!) Changed way to obtain error value. Added 1542 loadFile function for convenience. Made decodePNG32 faster. 1543 *) 21 jun 2006: (!) Changed type of info vector to unsigned. 1544 Changed position of palette in info vector. Fixed an important bug that 1545 happened on PNGs with an uncompressed block. 1546 *) 16 jun 2006: Internally changed unsigned into unsigned where 1547 needed, and performed some optimizations. 1548 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them 1549 in LodePNG namespace. Changed the order of the parameters. Rewrote the 1550 documentation in the header. Renamed files to lodepng.cpp and lodepng.h 1551 *) 22 apr 2006: Optimized and improved some code 1552 *) 07 sep 2005: (!) Changed to std::vector interface 1553 *) 12 aug 2005: Initial release (C++, decoder only) 1554 1555 1556 12. contact information 1557 ----------------------- 1558 1559 Feel free to contact me with suggestions, problems, comments, ... concerning 1560 LodePNG. If you encounter a PNG image that doesn't work properly with this 1561 decoder, feel free to send it and I'll use it to find and fix the problem. 1562 1563 My email address is (puzzle the account and domain together with an @ symbol): 1564 Domain: gmail dot com. 1565 Account: lode dot vandevenne. 1566 1567 1568 Copyright (c) 2005-2014 Lode Vandevenne 1569 */ 1570