1 /* 2 Copyright (c) 2005-2020 Intel Corporation 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 /* 18 LodePNG version 20160409 19 20 Copyright (c) 2005-2016 Lode Vandevenne 21 22 This software is provided 'as-is', without any express or implied 23 warranty. In no event will the authors be held liable for any damages 24 arising from the use of this software. 25 26 Permission is granted to anyone to use this software for any purpose, 27 including commercial applications, and to alter it and redistribute it 28 freely, subject to the following restrictions: 29 30 1. The origin of this software must not be misrepresented; you must not 31 claim that you wrote the original software. If you use this software 32 in a product, an acknowledgment in the product documentation would be 33 appreciated but is not required. 34 35 2. Altered source versions must be plainly marked as such, and must not be 36 misrepresented as being the original software. 37 38 3. This notice may not be removed or altered from any source 39 distribution. 40 */ 41 42 #ifndef LODEPNG_H 43 #define LODEPNG_H 44 45 #include <string.h> /*for size_t*/ 46 47 extern const char* LODEPNG_VERSION_STRING; 48 49 /* 50 The following #defines are used to create code sections. They can be disabled 51 to disable code sections, which can give faster compile time and smaller binary. 52 The "NO_COMPILE" defines are designed to be used to pass as defines to the 53 compiler command to disable them without modifying this header, e.g. 54 -DLODEPNG_NO_COMPILE_ZLIB for gcc. 55 In addition to those below, you can also define LODEPNG_NO_COMPILE_CRC to 56 allow implementing a custom lodepng_crc32. 57 */ 58 /*deflate & zlib. If disabled, you must specify alternative zlib functions in 59 the custom_zlib field of the compress and decompress settings*/ 60 #ifndef LODEPNG_NO_COMPILE_ZLIB 61 #define LODEPNG_COMPILE_ZLIB 62 #endif 63 /*png encoder and png decoder*/ 64 #ifndef LODEPNG_NO_COMPILE_PNG 65 #define LODEPNG_COMPILE_PNG 66 #endif 67 /*deflate&zlib decoder and png decoder*/ 68 #ifndef LODEPNG_NO_COMPILE_DECODER 69 #define LODEPNG_COMPILE_DECODER 70 #endif 71 /*deflate&zlib encoder and png encoder*/ 72 #ifndef LODEPNG_NO_COMPILE_ENCODER 73 #define LODEPNG_COMPILE_ENCODER 74 #endif 75 /*the optional built in harddisk file loading and saving functions*/ 76 #ifndef LODEPNG_NO_COMPILE_DISK 77 #define LODEPNG_COMPILE_DISK 78 #endif 79 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/ 80 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS 81 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS 82 #endif 83 /*ability to convert error numerical codes to English text string*/ 84 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT 85 #define LODEPNG_COMPILE_ERROR_TEXT 86 #endif 87 /*Compile the default allocators (C's free, malloc and realloc). If you disable this, 88 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your 89 source files with custom allocators.*/ 90 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS 91 #define LODEPNG_COMPILE_ALLOCATORS 92 #endif 93 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/ 94 #ifdef __cplusplus 95 #ifndef LODEPNG_NO_COMPILE_CPP 96 #define LODEPNG_COMPILE_CPP 97 #endif 98 #endif 99 100 #ifdef LODEPNG_COMPILE_CPP 101 #include <vector> 102 #include <string> 103 #endif /*LODEPNG_COMPILE_CPP*/ 104 105 #ifdef LODEPNG_COMPILE_PNG 106 /*The PNG color types (also used for raw).*/ 107 typedef enum LodePNGColorType 108 { 109 LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/ 110 LCT_RGB = 2, /*RGB: 8,16 bit*/ 111 LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/ 112 LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/ 113 LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/ 114 } LodePNGColorType; 115 116 #ifdef LODEPNG_COMPILE_DECODER 117 /* 118 Converts PNG data in memory to raw pixel data. 119 out: Output parameter. Pointer to buffer that will contain the raw pixel data. 120 After decoding, its size is w * h * (bytes per pixel) bytes larger than 121 initially. Bytes per pixel depends on colortype and bitdepth. 122 Must be freed after usage with free(*out). 123 Note: for 16-bit per channel colors, uses big endian format like PNG does. 124 w: Output parameter. Pointer to width of pixel data. 125 h: Output parameter. Pointer to height of pixel data. 126 in: Memory buffer with the PNG file. 127 insize: size of the in buffer. 128 colortype: the desired color type for the raw output image. See explanation on PNG color types. 129 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types. 130 Return value: LodePNG error code (0 means no error). 131 */ 132 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, 133 const unsigned char* in, size_t insize, 134 LodePNGColorType colortype, unsigned bitdepth); 135 136 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/ 137 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, 138 const unsigned char* in, size_t insize); 139 140 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/ 141 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, 142 const unsigned char* in, size_t insize); 143 144 #ifdef LODEPNG_COMPILE_DISK 145 /* 146 Load PNG from disk, from file with given name. 147 Same as the other decode functions, but instead takes a filename as input. 148 */ 149 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, 150 const char* filename, 151 LodePNGColorType colortype, unsigned bitdepth); 152 153 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.*/ 154 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, 155 const char* filename); 156 157 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.*/ 158 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, 159 const char* filename); 160 #endif /*LODEPNG_COMPILE_DISK*/ 161 #endif /*LODEPNG_COMPILE_DECODER*/ 162 163 164 #ifdef LODEPNG_COMPILE_ENCODER 165 /* 166 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth 167 of the output PNG image cannot be chosen, they are automatically determined 168 by the colortype, bitdepth and content of the input pixel data. 169 Note: for 16-bit per channel colors, needs big endian format like PNG does. 170 out: Output parameter. Pointer to buffer that will contain the PNG image data. 171 Must be freed after usage with free(*out). 172 outsize: Output parameter. Pointer to the size in bytes of the out buffer. 173 image: The raw pixel data to encode. The size of this buffer should be 174 w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth. 175 w: width of the raw pixel data in pixels. 176 h: height of the raw pixel data in pixels. 177 colortype: the color type of the raw input image. See explanation on PNG color types. 178 bitdepth: the bit depth of the raw input image. See explanation on PNG color types. 179 Return value: LodePNG error code (0 means no error). 180 */ 181 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, 182 const unsigned char* image, unsigned w, unsigned h, 183 LodePNGColorType colortype, unsigned bitdepth); 184 185 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/ 186 unsigned lodepng_encode32(unsigned char** out, size_t* outsize, 187 const unsigned char* image, unsigned w, unsigned h); 188 189 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/ 190 unsigned lodepng_encode24(unsigned char** out, size_t* outsize, 191 const unsigned char* image, unsigned w, unsigned h); 192 193 #ifdef LODEPNG_COMPILE_DISK 194 /* 195 Converts raw pixel data into a PNG file on disk. 196 Same as the other encode functions, but instead takes a filename as output. 197 NOTE: This overwrites existing files without warning! 198 */ 199 unsigned lodepng_encode_file(const char* filename, 200 const unsigned char* image, unsigned w, unsigned h, 201 LodePNGColorType colortype, unsigned bitdepth); 202 203 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.*/ 204 unsigned lodepng_encode32_file(const char* filename, 205 const unsigned char* image, unsigned w, unsigned h); 206 207 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.*/ 208 unsigned lodepng_encode24_file(const char* filename, 209 const unsigned char* image, unsigned w, unsigned h); 210 #endif /*LODEPNG_COMPILE_DISK*/ 211 #endif /*LODEPNG_COMPILE_ENCODER*/ 212 213 214 #ifdef LODEPNG_COMPILE_CPP 215 namespace lodepng 216 { 217 #ifdef LODEPNG_COMPILE_DECODER 218 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype 219 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/ 220 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 221 const unsigned char* in, size_t insize, 222 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 223 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 224 const std::vector<unsigned char>& in, 225 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 226 #ifdef LODEPNG_COMPILE_DISK 227 /* 228 Converts PNG file from disk to raw pixel data in memory. 229 Same as the other decode functions, but instead takes a filename as input. 230 */ 231 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 232 const std::string& filename, 233 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 234 #endif /* LODEPNG_COMPILE_DISK */ 235 #endif /* LODEPNG_COMPILE_DECODER */ 236 237 #ifdef LODEPNG_COMPILE_ENCODER 238 /*Same as lodepng_encode_memory, but encodes to an std::vector. colortype 239 is that of the raw input data. The output PNG color type will be auto chosen.*/ 240 unsigned encode(std::vector<unsigned char>& out, 241 const unsigned char* in, unsigned w, unsigned h, 242 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 243 unsigned encode(std::vector<unsigned char>& out, 244 const std::vector<unsigned char>& in, unsigned w, unsigned h, 245 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 246 #ifdef LODEPNG_COMPILE_DISK 247 /* 248 Converts 32-bit RGBA raw pixel data into a PNG file on disk. 249 Same as the other encode functions, but instead takes a filename as output. 250 NOTE: This overwrites existing files without warning! 251 */ 252 unsigned encode(const std::string& filename, 253 const unsigned char* in, unsigned w, unsigned h, 254 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 255 unsigned encode(const std::string& filename, 256 const std::vector<unsigned char>& in, unsigned w, unsigned h, 257 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 258 #endif /* LODEPNG_COMPILE_DISK */ 259 #endif /* LODEPNG_COMPILE_ENCODER */ 260 } /* namespace lodepng */ 261 #endif /*LODEPNG_COMPILE_CPP*/ 262 #endif /*LODEPNG_COMPILE_PNG*/ 263 264 #ifdef LODEPNG_COMPILE_ERROR_TEXT 265 /*Returns an English description of the numerical error code.*/ 266 const char* lodepng_error_text(unsigned code); 267 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/ 268 269 #ifdef LODEPNG_COMPILE_DECODER 270 /*Settings for zlib decompression*/ 271 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; 272 struct LodePNGDecompressSettings 273 { 274 unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ 275 276 /*use custom zlib decoder instead of built in one (default: null)*/ 277 unsigned (*custom_zlib)(unsigned char**, size_t*, 278 const unsigned char*, size_t, 279 const LodePNGDecompressSettings*); 280 /*use custom deflate decoder instead of built in one (default: null) 281 if custom_zlib is used, custom_deflate is ignored since only the built in 282 zlib function will call custom_deflate*/ 283 unsigned (*custom_inflate)(unsigned char**, size_t*, 284 const unsigned char*, size_t, 285 const LodePNGDecompressSettings*); 286 287 const void* custom_context; /*optional custom settings for custom functions*/ 288 }; 289 290 extern const LodePNGDecompressSettings lodepng_default_decompress_settings; 291 void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings); 292 #endif /*LODEPNG_COMPILE_DECODER*/ 293 294 #ifdef LODEPNG_COMPILE_ENCODER 295 /* 296 Settings for zlib compression. Tweaking these settings tweaks the balance 297 between speed and compression ratio. 298 */ 299 typedef struct LodePNGCompressSettings LodePNGCompressSettings; 300 struct LodePNGCompressSettings /*deflate = compress*/ 301 { 302 /*LZ77 related settings*/ 303 unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/ 304 unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ 305 unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/ 306 unsigned minmatch; /*minimum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ 307 unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/ 308 unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ 309 310 /*use custom zlib encoder instead of built in one (default: null)*/ 311 unsigned (*custom_zlib)(unsigned char**, size_t*, 312 const unsigned char*, size_t, 313 const LodePNGCompressSettings*); 314 /*use custom deflate encoder instead of built in one (default: null) 315 if custom_zlib is used, custom_deflate is ignored since only the built in 316 zlib function will call custom_deflate*/ 317 unsigned (*custom_deflate)(unsigned char**, size_t*, 318 const unsigned char*, size_t, 319 const LodePNGCompressSettings*); 320 321 const void* custom_context; /*optional custom settings for custom functions*/ 322 }; 323 324 extern const LodePNGCompressSettings lodepng_default_compress_settings; 325 void lodepng_compress_settings_init(LodePNGCompressSettings* settings); 326 #endif /*LODEPNG_COMPILE_ENCODER*/ 327 328 #ifdef LODEPNG_COMPILE_PNG 329 /* 330 Color mode of an image. Contains all information required to decode the pixel 331 bits to RGBA colors. This information is the same as used in the PNG file 332 format, and is used both for PNG and raw image data in LodePNG. 333 */ 334 typedef struct LodePNGColorMode 335 { 336 /*header (IHDR)*/ 337 LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/ 338 unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ 339 340 /* 341 palette (PLTE and tRNS) 342 343 Dynamically allocated with the colors of the palette, including alpha. 344 When encoding a PNG, to store your colors in the palette of the LodePNGColorMode, first use 345 lodepng_palette_clear, then for each color use lodepng_palette_add. 346 If you encode an image without alpha with palette, don't forget to put value 255 in each A byte of the palette. 347 348 When decoding, by default you can ignore this palette, since LodePNG already 349 fills the palette colors in the pixels of the raw RGBA output. 350 351 The palette is only supported for color type 3. 352 */ 353 unsigned char* palette; /*palette in RGBARGBA... order. When allocated, must be either 0, or have size 1024*/ 354 size_t palettesize; /*palette size in number of colors (amount of bytes is 4 * palettesize)*/ 355 356 /* 357 transparent color key (tRNS) 358 359 This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit. 360 For greyscale PNGs, r, g and b will all 3 be set to the same. 361 362 When decoding, by default you can ignore this information, since LodePNG sets 363 pixels with this key to transparent already in the raw RGBA output. 364 365 The color key is only supported for color types 0 and 2. 366 */ 367 unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ 368 unsigned key_r; /*red/greyscale component of color key*/ 369 unsigned key_g; /*green component of color key*/ 370 unsigned key_b; /*blue component of color key*/ 371 } LodePNGColorMode; 372 373 /*init, cleanup and copy functions to use with this struct*/ 374 void lodepng_color_mode_init(LodePNGColorMode* info); 375 void lodepng_color_mode_cleanup(LodePNGColorMode* info); 376 /*return value is error code (0 means no error)*/ 377 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source); 378 379 void lodepng_palette_clear(LodePNGColorMode* info); 380 /*add 1 color to the palette*/ 381 unsigned lodepng_palette_add(LodePNGColorMode* info, 382 unsigned char r, unsigned char g, unsigned char b, unsigned char a); 383 384 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ 385 unsigned lodepng_get_bpp(const LodePNGColorMode* info); 386 /*get the amount of color channels used, based on colortype in the struct. 387 If a palette is used, it counts as 1 channel.*/ 388 unsigned lodepng_get_channels(const LodePNGColorMode* info); 389 /*is it a greyscale type? (only colortype 0 or 4)*/ 390 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info); 391 /*has it got an alpha channel? (only colortype 2 or 6)*/ 392 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info); 393 /*has it got a palette? (only colortype 3)*/ 394 unsigned lodepng_is_palette_type(const LodePNGColorMode* info); 395 /*only returns true if there is a palette and there is a value in the palette with alpha < 255. 396 Loops through the palette to check this.*/ 397 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info); 398 /* 399 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image. 400 Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels). 401 Returns false if the image can only have opaque pixels. 402 In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values, 403 or if "key_defined" is true. 404 */ 405 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info); 406 /*Returns the byte size of a raw image buffer with given width, height and color mode*/ 407 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color); 408 409 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 410 /*The information of a Time chunk in PNG.*/ 411 typedef struct LodePNGTime 412 { 413 unsigned year; /*2 bytes used (0-65535)*/ 414 unsigned month; /*1-12*/ 415 unsigned day; /*1-31*/ 416 unsigned hour; /*0-23*/ 417 unsigned minute; /*0-59*/ 418 unsigned second; /*0-60 (to allow for leap seconds)*/ 419 } LodePNGTime; 420 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 421 422 /*Information about the PNG image, except pixels, width and height.*/ 423 typedef struct LodePNGInfo 424 { 425 /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ 426 unsigned compression_method;/*compression method of the original file. Always 0.*/ 427 unsigned filter_method; /*filter method of the original file*/ 428 unsigned interlace_method; /*interlace method of the original file*/ 429 LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/ 430 431 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 432 /* 433 suggested background color chunk (bKGD) 434 This color uses the same color mode as the PNG (except alpha channel), which can be 1-bit to 16-bit. 435 436 For greyscale PNGs, r, g and b will all 3 be set to the same. When encoding 437 the encoder writes the red one. For palette PNGs: When decoding, the RGB value 438 will be stored, not a palette index. But when encoding, specify the index of 439 the palette in background_r, the other two are then ignored. 440 441 The decoder does not use this background color to edit the color of pixels. 442 */ 443 unsigned background_defined; /*is a suggested background color given?*/ 444 unsigned background_r; /*red component of suggested background color*/ 445 unsigned background_g; /*green component of suggested background color*/ 446 unsigned background_b; /*blue component of suggested background color*/ 447 448 /* 449 non-international text chunks (tEXt and zTXt) 450 451 The char** arrays each contain num strings. The actual messages are in 452 text_strings, while text_keys are keywords that give a short description what 453 the actual text represents, e.g. Title, Author, Description, or anything else. 454 455 A keyword is minimum 1 character and maximum 79 characters long. It's 456 discouraged to use a single line length longer than 79 characters for texts. 457 458 Don't allocate these text buffers yourself. Use the init/cleanup functions 459 correctly and use lodepng_add_text and lodepng_clear_text. 460 */ 461 size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/ 462 char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/ 463 char** text_strings; /*the actual text*/ 464 465 /* 466 international text chunks (iTXt) 467 Similar to the non-international text chunks, but with additional strings 468 "langtags" and "transkeys". 469 */ 470 size_t itext_num; /*the amount of international texts in this PNG*/ 471 char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ 472 char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/ 473 char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/ 474 char** itext_strings; /*the actual international text - UTF-8 string*/ 475 476 /*time chunk (tIME)*/ 477 unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ 478 LodePNGTime time; 479 480 /*phys chunk (pHYs)*/ 481 unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/ 482 unsigned phys_x; /*pixels per unit in x direction*/ 483 unsigned phys_y; /*pixels per unit in y direction*/ 484 unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ 485 486 /* 487 unknown chunks 488 There are 3 buffers, one for each position in the PNG where unknown chunks can appear 489 each buffer contains all unknown chunks for that position consecutively 490 The 3 buffers are the unknown chunks between certain critical chunks: 491 0: IHDR-PLTE, 1: PLTE-IDAT, 2: IDAT-IEND 492 Do not allocate or traverse this data yourself. Use the chunk traversing functions declared 493 later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct. 494 */ 495 unsigned char* unknown_chunks_data[3]; 496 size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ 497 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 498 } LodePNGInfo; 499 500 /*init, cleanup and copy functions to use with this struct*/ 501 void lodepng_info_init(LodePNGInfo* info); 502 void lodepng_info_cleanup(LodePNGInfo* info); 503 /*return value is error code (0 means no error)*/ 504 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source); 505 506 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 507 void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ 508 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/ 509 510 void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ 511 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag, 512 const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/ 513 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 514 515 /* 516 Converts raw buffer from one color type to another color type, based on 517 LodePNGColorMode structs to describe the input and output color type. 518 See the reference manual at the end of this header file to see which color conversions are supported. 519 return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported) 520 The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel 521 of the output color type (lodepng_get_bpp). 522 For < 8 bpp images, there should not be padding bits at the end of scanlines. 523 For 16-bit per channel colors, uses big endian format like PNG does. 524 Return value is LodePNG error code 525 */ 526 unsigned lodepng_convert(unsigned char* out, const unsigned char* in, 527 const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in, 528 unsigned w, unsigned h); 529 530 #ifdef LODEPNG_COMPILE_DECODER 531 /* 532 Settings for the decoder. This contains settings for the PNG and the Zlib 533 decoder, but not the Info settings from the Info structs. 534 */ 535 typedef struct LodePNGDecoderSettings 536 { 537 LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ 538 539 unsigned ignore_crc; /*ignore CRC checksums*/ 540 541 unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ 542 543 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 544 unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/ 545 /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/ 546 unsigned remember_unknown_chunks; 547 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 548 } LodePNGDecoderSettings; 549 550 void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); 551 #endif /*LODEPNG_COMPILE_DECODER*/ 552 553 #ifdef LODEPNG_COMPILE_ENCODER 554 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ 555 typedef enum LodePNGFilterStrategy 556 { 557 /*every filter at zero*/ 558 LFS_ZERO, 559 /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/ 560 LFS_MINSUM, 561 /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending 562 on the image, this is better or worse than minsum.*/ 563 LFS_ENTROPY, 564 /* 565 Brute-force-search PNG filters by compressing each filter for each scanline. 566 Experimental, very slow, and only rarely gives better compression than MINSUM. 567 */ 568 LFS_BRUTE_FORCE, 569 /*use predefined_filters buffer: you specify the filter type for each scanline*/ 570 LFS_PREDEFINED 571 } LodePNGFilterStrategy; 572 573 /*Gives characteristics about the colors of the image, which helps decide which color model to use for encoding. 574 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/ 575 typedef struct LodePNGColorProfile 576 { 577 unsigned colored; /*not greyscale*/ 578 unsigned key; /*if true, image is not opaque. Only if true and alpha is false, color key is possible.*/ 579 unsigned short key_r; /*these values are always in 16-bit bitdepth in the profile*/ 580 unsigned short key_g; 581 unsigned short key_b; 582 unsigned alpha; /*alpha channel or alpha palette required*/ 583 unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16.*/ 584 unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order*/ 585 unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for greyscale only. 16 if 16-bit per channel required.*/ 586 } LodePNGColorProfile; 587 588 void lodepng_color_profile_init(LodePNGColorProfile* profile); 589 590 /*Get a LodePNGColorProfile of the image.*/ 591 unsigned lodepng_get_color_profile(LodePNGColorProfile* profile, 592 const unsigned char* image, unsigned w, unsigned h, 593 const LodePNGColorMode* mode_in); 594 /*The function LodePNG uses internally to decide the PNG color with auto_convert. 595 Chooses an optimal color model, e.g. grey if only grey pixels, palette if < 256 colors, ...*/ 596 unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out, 597 const unsigned char* image, unsigned w, unsigned h, 598 const LodePNGColorMode* mode_in); 599 600 /*Settings for the encoder.*/ 601 typedef struct LodePNGEncoderSettings 602 { 603 LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ 604 605 unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/ 606 607 /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than 608 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to 609 completely follow the official PNG heuristic, filter_palette_zero must be true and 610 filter_strategy must be LFS_MINSUM*/ 611 unsigned filter_palette_zero; 612 /*Which filter strategy to use when not using zeroes due to filter_palette_zero. 613 Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/ 614 LodePNGFilterStrategy filter_strategy; 615 /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with 616 the same length as the amount of scanlines in the image, and each value must <= 5. You 617 have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero 618 must be set to 0 to ensure this is also used on palette or low bitdepth images.*/ 619 const unsigned char* predefined_filters; 620 621 /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). 622 If colortype is 3, PLTE is _always_ created.*/ 623 unsigned force_palette; 624 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 625 /*add LodePNG identifier and version as a text chunk, for debugging*/ 626 unsigned add_id; 627 /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ 628 unsigned text_compression; 629 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 630 } LodePNGEncoderSettings; 631 632 void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); 633 #endif /*LODEPNG_COMPILE_ENCODER*/ 634 635 636 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) 637 /*The settings, state and information for extended encoding and decoding.*/ 638 typedef struct LodePNGState 639 { 640 #ifdef LODEPNG_COMPILE_DECODER 641 LodePNGDecoderSettings decoder; /*the decoding settings*/ 642 #endif /*LODEPNG_COMPILE_DECODER*/ 643 #ifdef LODEPNG_COMPILE_ENCODER 644 LodePNGEncoderSettings encoder; /*the encoding settings*/ 645 #endif /*LODEPNG_COMPILE_ENCODER*/ 646 LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ 647 LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/ 648 unsigned error; 649 #ifdef LODEPNG_COMPILE_CPP 650 /* For the lodepng::State subclass. */ ~LodePNGStateLodePNGState651 virtual ~LodePNGState(){} 652 #endif 653 } LodePNGState; 654 655 /*init, cleanup and copy functions to use with this struct*/ 656 void lodepng_state_init(LodePNGState* state); 657 void lodepng_state_cleanup(LodePNGState* state); 658 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source); 659 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */ 660 661 #ifdef LODEPNG_COMPILE_DECODER 662 /* 663 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and 664 getting much more information about the PNG image and color mode. 665 */ 666 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, 667 LodePNGState* state, 668 const unsigned char* in, size_t insize); 669 670 /* 671 Read the PNG header, but not the actual data. This returns only the information 672 that is in the header chunk of the PNG, such as width, height and color type. The 673 information is placed in the info_png field of the LodePNGState. 674 */ 675 unsigned lodepng_inspect(unsigned* w, unsigned* h, 676 LodePNGState* state, 677 const unsigned char* in, size_t insize); 678 #endif /*LODEPNG_COMPILE_DECODER*/ 679 680 681 #ifdef LODEPNG_COMPILE_ENCODER 682 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ 683 unsigned lodepng_encode(unsigned char** out, size_t* outsize, 684 const unsigned char* image, unsigned w, unsigned h, 685 LodePNGState* state); 686 #endif /*LODEPNG_COMPILE_ENCODER*/ 687 688 /* 689 The lodepng_chunk functions are normally not needed, except to traverse the 690 unknown chunks stored in the LodePNGInfo struct, or add new ones to it. 691 It also allows traversing the chunks of an encoded PNG file yourself. 692 693 PNG standard chunk naming conventions: 694 First byte: uppercase = critical, lowercase = ancillary 695 Second byte: uppercase = public, lowercase = private 696 Third byte: must be uppercase 697 Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy 698 */ 699 700 /* 701 Gets the length of the data of the chunk. Total chunk length has 12 bytes more. 702 There must be at least 4 bytes to read from. If the result value is too large, 703 it may be corrupt data. 704 */ 705 unsigned lodepng_chunk_length(const unsigned char* chunk); 706 707 /*puts the 4-byte type in null terminated string*/ 708 void lodepng_chunk_type(char type[5], const unsigned char* chunk); 709 710 /*check if the type is the given type*/ 711 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type); 712 713 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ 714 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk); 715 716 /*0: public, 1: private (see PNG standard)*/ 717 unsigned char lodepng_chunk_private(const unsigned char* chunk); 718 719 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ 720 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk); 721 722 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/ 723 unsigned char* lodepng_chunk_data(unsigned char* chunk); 724 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk); 725 726 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ 727 unsigned lodepng_chunk_check_crc(const unsigned char* chunk); 728 729 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ 730 void lodepng_chunk_generate_crc(unsigned char* chunk); 731 732 /*iterate to next chunks. don't use on IEND chunk, as there is no next chunk then*/ 733 unsigned char* lodepng_chunk_next(unsigned char* chunk); 734 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk); 735 736 /* 737 Appends chunk to the data in out. The given chunk should already have its chunk header. 738 The out variable and outlength are updated to reflect the new reallocated buffer. 739 Returns error code (0 if it went ok) 740 */ 741 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk); 742 743 /* 744 Appends new chunk to out. The chunk to append is given by giving its length, type 745 and data separately. The type is a 4-letter string. 746 The out variable and outlength are updated to reflect the new reallocated buffer. 747 Returne error code (0 if it went ok) 748 */ 749 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 750 const char* type, const unsigned char* data); 751 752 753 /*Calculate CRC32 of buffer*/ 754 unsigned lodepng_crc32(const unsigned char* buf, size_t len); 755 #endif /*LODEPNG_COMPILE_PNG*/ 756 757 758 #ifdef LODEPNG_COMPILE_ZLIB 759 /* 760 This zlib part can be used independently to zlib compress and decompress a 761 buffer. It cannot be used to create gzip files however, and it only supports the 762 part of zlib that is required for PNG, it does not support dictionaries. 763 */ 764 765 #ifdef LODEPNG_COMPILE_DECODER 766 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/ 767 unsigned lodepng_inflate(unsigned char** out, size_t* outsize, 768 const unsigned char* in, size_t insize, 769 const LodePNGDecompressSettings* settings); 770 771 /* 772 Decompresses Zlib data. Reallocates the out buffer and appends the data. The 773 data must be according to the zlib specification. 774 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 775 buffer and *outsize its size in bytes. out must be freed by user after usage. 776 */ 777 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, 778 const unsigned char* in, size_t insize, 779 const LodePNGDecompressSettings* settings); 780 #endif /*LODEPNG_COMPILE_DECODER*/ 781 782 #ifdef LODEPNG_COMPILE_ENCODER 783 /* 784 Compresses data with Zlib. Reallocates the out buffer and appends the data. 785 Zlib adds a small header and trailer around the deflate data. 786 The data is output in the format of the zlib specification. 787 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 788 buffer and *outsize its size in bytes. out must be freed by user after usage. 789 */ 790 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, 791 const unsigned char* in, size_t insize, 792 const LodePNGCompressSettings* settings); 793 794 /* 795 Find length-limited Huffman code for given frequencies. This function is in the 796 public interface only for tests, it's used internally by lodepng_deflate. 797 */ 798 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies, 799 size_t numcodes, unsigned maxbitlen); 800 801 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ 802 unsigned lodepng_deflate(unsigned char** out, size_t* outsize, 803 const unsigned char* in, size_t insize, 804 const LodePNGCompressSettings* settings); 805 806 #endif /*LODEPNG_COMPILE_ENCODER*/ 807 #endif /*LODEPNG_COMPILE_ZLIB*/ 808 809 #ifdef LODEPNG_COMPILE_DISK 810 /* 811 Load a file from disk into buffer. The function allocates the out buffer, and 812 after usage you should free it. 813 out: output parameter, contains pointer to loaded buffer. 814 outsize: output parameter, size of the allocated out buffer 815 filename: the path to the file to load 816 return value: error code (0 means ok) 817 */ 818 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename); 819 820 /* 821 Save a file from buffer to disk. Warning, if it exists, this function overwrites 822 the file without warning! 823 buffer: the buffer to write 824 buffersize: size of the buffer to write 825 filename: the path to the file to save to 826 return value: error code (0 means ok) 827 */ 828 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename); 829 #endif /*LODEPNG_COMPILE_DISK*/ 830 831 #ifdef LODEPNG_COMPILE_CPP 832 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */ 833 namespace lodepng 834 { 835 #ifdef LODEPNG_COMPILE_PNG 836 class State : public LodePNGState 837 { 838 public: 839 State(); 840 State(const State& other); 841 virtual ~State(); 842 State& operator=(const State& other); 843 }; 844 845 #ifdef LODEPNG_COMPILE_DECODER 846 /* Same as other lodepng::decode, but using a State for more settings and information. */ 847 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 848 State& state, 849 const unsigned char* in, size_t insize); 850 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 851 State& state, 852 const std::vector<unsigned char>& in); 853 #endif /*LODEPNG_COMPILE_DECODER*/ 854 855 #ifdef LODEPNG_COMPILE_ENCODER 856 /* Same as other lodepng::encode, but using a State for more settings and information. */ 857 unsigned encode(std::vector<unsigned char>& out, 858 const unsigned char* in, unsigned w, unsigned h, 859 State& state); 860 unsigned encode(std::vector<unsigned char>& out, 861 const std::vector<unsigned char>& in, unsigned w, unsigned h, 862 State& state); 863 #endif /*LODEPNG_COMPILE_ENCODER*/ 864 865 #ifdef LODEPNG_COMPILE_DISK 866 /* 867 Load a file from disk into an std::vector. 868 return value: error code (0 means ok) 869 */ 870 unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename); 871 872 /* 873 Save the binary data in an std::vector to a file on disk. The file is overwritten 874 without warning. 875 */ 876 unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename); 877 #endif /* LODEPNG_COMPILE_DISK */ 878 #endif /* LODEPNG_COMPILE_PNG */ 879 880 #ifdef LODEPNG_COMPILE_ZLIB 881 #ifdef LODEPNG_COMPILE_DECODER 882 /* Zlib-decompress an unsigned char buffer */ 883 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 884 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 885 886 /* Zlib-decompress an std::vector */ 887 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 888 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 889 #endif /* LODEPNG_COMPILE_DECODER */ 890 891 #ifdef LODEPNG_COMPILE_ENCODER 892 /* Zlib-compress an unsigned char buffer */ 893 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 894 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 895 896 /* Zlib-compress an std::vector */ 897 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 898 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 899 #endif /* LODEPNG_COMPILE_ENCODER */ 900 #endif /* LODEPNG_COMPILE_ZLIB */ 901 } /* namespace lodepng */ 902 #endif /*LODEPNG_COMPILE_CPP*/ 903 904 /* 905 TODO: 906 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often 907 [.] check compatibility with various compilers - done but needs to be redone for every newer version 908 [X] converting color to 16-bit per channel types 909 [ ] read all public PNG chunk types (but never let the color profile and gamma ones touch RGB values) 910 [ ] make sure encoder generates no chunks with size > (2^31)-1 911 [ ] partial decoding (stream processing) 912 [X] let the "isFullyOpaque" function check color keys and transparent palettes too 913 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl" 914 [ ] don't stop decoding on errors like 69, 57, 58 (make warnings) 915 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes 916 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ... 917 [ ] allow user to give data (void*) to custom allocator 918 */ 919 920 #endif /*LODEPNG_H inclusion guard*/ 921 922 /* 923 LodePNG Documentation 924 --------------------- 925 926 0. table of contents 927 -------------------- 928 929 1. about 930 1.1. supported features 931 1.2. features not supported 932 2. C and C++ version 933 3. security 934 4. decoding 935 5. encoding 936 6. color conversions 937 6.1. PNG color types 938 6.2. color conversions 939 6.3. padding bits 940 6.4. A note about 16-bits per channel and endianness 941 7. error values 942 8. chunks and PNG editing 943 9. compiler support 944 10. examples 945 10.1. decoder C++ example 946 10.2. decoder C example 947 11. state settings reference 948 12. changes 949 13. contact information 950 951 952 1. about 953 -------- 954 955 PNG is a file format to store raster images losslessly with good compression, 956 supporting different color types and alpha channel. 957 958 LodePNG is a PNG codec according to the Portable Network Graphics (PNG) 959 Specification (Second Edition) - W3C Recommendation 10 November 2003. 960 961 The specifications used are: 962 963 *) Portable Network Graphics (PNG) Specification (Second Edition): 964 http://www.w3.org/TR/2003/REC-PNG-20031110 965 *) RFC 1950 ZLIB Compressed Data Format version 3.3: 966 http://www.gzip.org/zlib/rfc-zlib.html 967 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3: 968 http://www.gzip.org/zlib/rfc-deflate.html 969 970 The most recent version of LodePNG can currently be found at 971 http://lodev.org/lodepng/ 972 973 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds 974 extra functionality. 975 976 LodePNG exists out of two files: 977 -lodepng.h: the header file for both C and C++ 978 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage 979 980 If you want to start using LodePNG right away without reading this doc, get the 981 examples from the LodePNG website to see how to use it in code, or check the 982 smaller examples in chapter 13 here. 983 984 LodePNG is simple but only supports the basic requirements. To achieve 985 simplicity, the following design choices were made: There are no dependencies 986 on any external library. There are functions to decode and encode a PNG with 987 a single function call, and extended versions of these functions taking a 988 LodePNGState struct allowing to specify or get more information. By default 989 the colors of the raw image are always RGB or RGBA, no matter what color type 990 the PNG file uses. To read and write files, there are simple functions to 991 convert the files to/from buffers in memory. 992 993 This all makes LodePNG suitable for loading textures in games, demos and small 994 programs, ... It's less suitable for full fledged image editors, loading PNGs 995 over network (it requires all the image data to be available before decoding can 996 begin), life-critical systems, ... 997 998 1.1. supported features 999 ----------------------- 1000 1001 The following features are supported by the decoder: 1002 1003 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image, 1004 or the same color type as the PNG 1005 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image 1006 *) Adam7 interlace and deinterlace for any color type 1007 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk 1008 *) support for alpha channels, including RGBA color model, translucent palettes and color keying 1009 *) zlib decompression (inflate) 1010 *) zlib compression (deflate) 1011 *) CRC32 and ADLER32 checksums 1012 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks. 1013 *) the following chunks are supported (generated/interpreted) by both encoder and decoder: 1014 IHDR: header information 1015 PLTE: color palette 1016 IDAT: pixel data 1017 IEND: the final chunk 1018 tRNS: transparency for palettized images 1019 tEXt: textual information 1020 zTXt: compressed textual information 1021 iTXt: international textual information 1022 bKGD: suggested background color 1023 pHYs: physical dimensions 1024 tIME: modification time 1025 1026 1.2. features not supported 1027 --------------------------- 1028 1029 The following features are _not_ supported: 1030 1031 *) some features needed to make a conformant PNG-Editor might be still missing. 1032 *) partial loading/stream processing. All data must be available and is processed in one call. 1033 *) The following public chunks are not supported but treated as unknown chunks by LodePNG 1034 cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT 1035 Some of these are not supported on purpose: LodePNG wants to provide the RGB values 1036 stored in the pixels, not values modified by system dependent gamma or color models. 1037 1038 1039 2. C and C++ version 1040 -------------------- 1041 1042 The C version uses buffers allocated with alloc that you need to free() 1043 yourself. You need to use init and cleanup functions for each struct whenever 1044 using a struct from the C version to avoid exploits and memory leaks. 1045 1046 The C++ version has extra functions with std::vectors in the interface and the 1047 lodepng::State class which is a LodePNGState with constructor and destructor. 1048 1049 These files work without modification for both C and C++ compilers because all 1050 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers 1051 ignore it, and the C code is made to compile both with strict ISO C90 and C++. 1052 1053 To use the C++ version, you need to rename the source file to lodepng.cpp 1054 (instead of lodepng.c), and compile it with a C++ compiler. 1055 1056 To use the C version, you need to rename the source file to lodepng.c (instead 1057 of lodepng.cpp), and compile it with a C compiler. 1058 1059 1060 3. Security 1061 ----------- 1062 1063 Even if carefully designed, it's always possible that LodePNG contains possible 1064 exploits. If you discover one, please let me know, and it will be fixed. 1065 1066 When using LodePNG, care has to be taken with the C version of LodePNG, as well 1067 as the C-style structs when working with C++. The following conventions are used 1068 for all C-style structs: 1069 1070 -if a struct has a corresponding init function, always call the init function when making a new one 1071 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks 1072 -if a struct has a corresponding copy function, use the copy function instead of "=". 1073 The destination must also be inited already. 1074 1075 1076 4. Decoding 1077 ----------- 1078 1079 Decoding converts a PNG compressed image to a raw pixel buffer. 1080 1081 Most documentation on using the decoder is at its declarations in the header 1082 above. For C, simple decoding can be done with functions such as 1083 lodepng_decode32, and more advanced decoding can be done with the struct 1084 LodePNGState and lodepng_decode. For C++, all decoding can be done with the 1085 various lodepng::decode functions, and lodepng::State can be used for advanced 1086 features. 1087 1088 When using the LodePNGState, it uses the following fields for decoding: 1089 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here 1090 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get 1091 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use 1092 1093 LodePNGInfo info_png 1094 -------------------- 1095 1096 After decoding, this contains extra information of the PNG image, except the actual 1097 pixels, width and height because these are already gotten directly from the decoder 1098 functions. 1099 1100 It contains for example the original color type of the PNG image, text comments, 1101 suggested background color, etc... More details about the LodePNGInfo struct are 1102 at its declaration documentation. 1103 1104 LodePNGColorMode info_raw 1105 ------------------------- 1106 1107 When decoding, here you can specify which color type you want 1108 the resulting raw image to be. If this is different from the colortype of the 1109 PNG, then the decoder will automatically convert the result. This conversion 1110 always works, except if you want it to convert a color PNG to greyscale or to 1111 a palette with missing colors. 1112 1113 By default, 32-bit color is used for the result. 1114 1115 LodePNGDecoderSettings decoder 1116 ------------------------------ 1117 1118 The settings can be used to ignore the errors created by invalid CRC and Adler32 1119 chunks, and to disable the decoding of tEXt chunks. 1120 1121 There's also a setting color_convert, true by default. If false, no conversion 1122 is done, the resulting data will be as it was in the PNG (after decompression) 1123 and you'll have to puzzle the colors of the pixels together yourself using the 1124 color type information in the LodePNGInfo. 1125 1126 1127 5. Encoding 1128 ----------- 1129 1130 Encoding converts a raw pixel buffer to a PNG compressed image. 1131 1132 Most documentation on using the encoder is at its declarations in the header 1133 above. For C, simple encoding can be done with functions such as 1134 lodepng_encode32, and more advanced decoding can be done with the struct 1135 LodePNGState and lodepng_encode. For C++, all encoding can be done with the 1136 various lodepng::encode functions, and lodepng::State can be used for advanced 1137 features. 1138 1139 Like the decoder, the encoder can also give errors. However it gives less errors 1140 since the encoder input is trusted, the decoder input (a PNG image that could 1141 be forged by anyone) is not trusted. 1142 1143 When using the LodePNGState, it uses the following fields for encoding: 1144 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be. 1145 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has 1146 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use 1147 1148 LodePNGInfo info_png 1149 -------------------- 1150 1151 When encoding, you use this the opposite way as when decoding: for encoding, 1152 you fill in the values you want the PNG to have before encoding. By default it's 1153 not needed to specify a color type for the PNG since it's automatically chosen, 1154 but it's possible to choose it yourself given the right settings. 1155 1156 The encoder will not always exactly match the LodePNGInfo struct you give, 1157 it tries as close as possible. Some things are ignored by the encoder. The 1158 encoder uses, for example, the following settings from it when applicable: 1159 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the 1160 background color, the interlace method, unknown chunks, ... 1161 1162 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk. 1163 If the palette contains any colors for which the alpha channel is not 255 (so 1164 there are translucent colors in the palette), it'll add a tRNS chunk. 1165 1166 LodePNGColorMode info_raw 1167 ------------------------- 1168 1169 You specify the color type of the raw image that you give to the input here, 1170 including a possible transparent color key and palette you happen to be using in 1171 your raw image data. 1172 1173 By default, 32-bit color is assumed, meaning your input has to be in RGBA 1174 format with 4 bytes (unsigned chars) per pixel. 1175 1176 LodePNGEncoderSettings encoder 1177 ------------------------------ 1178 1179 The following settings are supported (some are in sub-structs): 1180 *) auto_convert: when this option is enabled, the encoder will 1181 automatically choose the smallest possible color mode (including color key) that 1182 can encode the colors of all pixels without information loss. 1183 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree, 1184 2 = dynamic huffman tree (best compression). Should be 2 for proper 1185 compression. 1186 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be 1187 true for proper compression. 1188 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value 1189 2048 by default, but can be set to 32768 for better, but slow, compression. 1190 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE 1191 chunk if force_palette is true. This can used as suggested palette to convert 1192 to by viewers that don't support more than 256 colors (if those still exist) 1193 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image. 1194 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks. 1195 zTXt chunks use zlib compression on the text. This gives a smaller result on 1196 large texts but a larger result on small texts (such as a single program name). 1197 It's all tEXt or all zTXt though, there's no separate setting per text yet. 1198 1199 1200 6. color conversions 1201 -------------------- 1202 1203 An important thing to note about LodePNG, is that the color type of the PNG, and 1204 the color type of the raw image, are completely independent. By default, when 1205 you decode a PNG, you get the result as a raw image in the color type you want, 1206 no matter whether the PNG was encoded with a palette, greyscale or RGBA color. 1207 And if you encode an image, by default LodePNG will automatically choose the PNG 1208 color type that gives good compression based on the values of colors and amount 1209 of colors in the image. It can be configured to let you control it instead as 1210 well, though. 1211 1212 To be able to do this, LodePNG does conversions from one color mode to another. 1213 It can convert from almost any color type to any other color type, except the 1214 following conversions: RGB to greyscale is not supported, and converting to a 1215 palette when the palette doesn't have a required color is not supported. This is 1216 not supported on purpose: this is information loss which requires a color 1217 reduction algorithm that is beyond the scope of a PNG encoder (yes, RGB to grey 1218 is easy, but there are multiple ways if you want to give some channels more 1219 weight). 1220 1221 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB 1222 color, no matter what color type the PNG has. And by default when encoding, 1223 LodePNG automatically picks the best color model for the output PNG, and expects 1224 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control 1225 the color format of the images yourself, you can skip this chapter. 1226 1227 6.1. PNG color types 1228 -------------------- 1229 1230 A PNG image can have many color types, ranging from 1-bit color to 64-bit color, 1231 as well as palettized color modes. After the zlib decompression and unfiltering 1232 in the PNG image is done, the raw pixel data will have that color type and thus 1233 a certain amount of bits per pixel. If you want the output raw image after 1234 decoding to have another color type, a conversion is done by LodePNG. 1235 1236 The PNG specification gives the following color types: 1237 1238 0: greyscale, bit depths 1, 2, 4, 8, 16 1239 2: RGB, bit depths 8 and 16 1240 3: palette, bit depths 1, 2, 4 and 8 1241 4: greyscale with alpha, bit depths 8 and 16 1242 6: RGBA, bit depths 8 and 16 1243 1244 Bit depth is the amount of bits per pixel per color channel. So the total amount 1245 of bits per pixel is: amount of channels * bitdepth. 1246 1247 6.2. color conversions 1248 ---------------------- 1249 1250 As explained in the sections about the encoder and decoder, you can specify 1251 color types and bit depths in info_png and info_raw to change the default 1252 behaviour. 1253 1254 If, when decoding, you want the raw image to be something else than the default, 1255 you need to set the color type and bit depth you want in the LodePNGColorMode, 1256 or the parameters colortype and bitdepth of the simple decoding function. 1257 1258 If, when encoding, you use another color type than the default in the raw input 1259 image, you need to specify its color type and bit depth in the LodePNGColorMode 1260 of the raw image, or use the parameters colortype and bitdepth of the simple 1261 encoding function. 1262 1263 If, when encoding, you don't want LodePNG to choose the output PNG color type 1264 but control it yourself, you need to set auto_convert in the encoder settings 1265 to false, and specify the color type you want in the LodePNGInfo of the 1266 encoder (including palette: it can generate a palette if auto_convert is true, 1267 otherwise not). 1268 1269 If the input and output color type differ (whether user chosen or auto chosen), 1270 LodePNG will do a color conversion, which follows the rules below, and may 1271 sometimes result in an error. 1272 1273 To avoid some confusion: 1274 -the decoder converts from PNG to raw image 1275 -the encoder converts from raw image to PNG 1276 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image 1277 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG 1278 -when encoding, the color type in LodePNGInfo is ignored if auto_convert 1279 is enabled, it is automatically generated instead 1280 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original 1281 PNG image, but it can be ignored since the raw image has the color type you requested instead 1282 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion 1283 between the color types is done if the color types are supported. If it is not 1284 supported, an error is returned. If the types are the same, no conversion is done. 1285 -even though some conversions aren't supported, LodePNG supports loading PNGs from any 1286 colortype and saving PNGs to any colortype, sometimes it just requires preparing 1287 the raw image correctly before encoding. 1288 -both encoder and decoder use the same color converter. 1289 1290 Non supported color conversions: 1291 -color to greyscale: no error is thrown, but the result will look ugly because 1292 only the red channel is taken 1293 -anything to palette when that palette does not have that color in it: in this 1294 case an error is thrown 1295 1296 Supported color conversions: 1297 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA 1298 -any grey or grey+alpha, to grey or grey+alpha 1299 -anything to a palette, as long as the palette has the requested colors in it 1300 -removing alpha channel 1301 -higher to smaller bitdepth, and vice versa 1302 1303 If you want no color conversion to be done (e.g. for speed or control): 1304 -In the encoder, you can make it save a PNG with any color type by giving the 1305 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to 1306 false. 1307 -In the decoder, you can make it store the pixel data in the same color type 1308 as the PNG has, by setting the color_convert setting to false. Settings in 1309 info_raw are then ignored. 1310 1311 The function lodepng_convert does the color conversion. It is available in the 1312 interface but normally isn't needed since the encoder and decoder already call 1313 it. 1314 1315 6.3. padding bits 1316 ----------------- 1317 1318 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines 1319 have a bit amount that isn't a multiple of 8, then padding bits are used so that each 1320 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output. 1321 The raw input image you give to the encoder, and the raw output image you get from the decoder 1322 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width 1323 of 7 pixels, the first pixel of the second scanline will the the 8th bit of the first byte, 1324 not the first bit of a new byte. 1325 1326 6.4. A note about 16-bits per channel and endianness 1327 ---------------------------------------------------- 1328 1329 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like 1330 for any other color format. The 16-bit values are stored in big endian (most 1331 significant byte first) in these arrays. This is the opposite order of the 1332 little endian used by x86 CPU's. 1333 1334 LodePNG always uses big endian because the PNG file format does so internally. 1335 Conversions to other formats than PNG uses internally are not supported by 1336 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit 1337 colors, the order in which you store R, G, B and A, and so on. Supporting and 1338 converting to/from all that is outside the scope of LodePNG. 1339 1340 This may mean that, depending on your use case, you may want to convert the big 1341 endian output of LodePNG to little endian with a for loop. This is certainly not 1342 always needed, many applications and libraries support big endian 16-bit colors 1343 anyway, but it means you cannot simply cast the unsigned char* buffer to an 1344 unsigned short* buffer on x86 CPUs. 1345 1346 1347 7. error values 1348 --------------- 1349 1350 All functions in LodePNG that return an error code, return 0 if everything went 1351 OK, or a non-zero code if there was an error. 1352 1353 The meaning of the LodePNG error values can be retrieved with the function 1354 lodepng_error_text: given the numerical error code, it returns a description 1355 of the error in English as a string. 1356 1357 Check the implementation of lodepng_error_text to see the meaning of each code. 1358 1359 1360 8. chunks and PNG editing 1361 ------------------------- 1362 1363 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG 1364 editor that should follow the rules about handling of unknown chunks, or if your 1365 program is able to read other types of chunks than the ones handled by LodePNG, 1366 then that's possible with the chunk functions of LodePNG. 1367 1368 A PNG chunk has the following layout: 1369 1370 4 bytes length 1371 4 bytes type name 1372 length bytes data 1373 4 bytes CRC 1374 1375 8.1. iterating through chunks 1376 ----------------------------- 1377 1378 If you have a buffer containing the PNG image data, then the first chunk (the 1379 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the 1380 signature of the PNG and are not part of a chunk. But if you start at byte 8 1381 then you have a chunk, and can check the following things of it. 1382 1383 NOTE: none of these functions check for memory buffer boundaries. To avoid 1384 exploits, always make sure the buffer contains all the data of the chunks. 1385 When using lodepng_chunk_next, make sure the returned value is within the 1386 allocated memory. 1387 1388 unsigned lodepng_chunk_length(const unsigned char* chunk): 1389 1390 Get the length of the chunk's data. The total chunk length is this length + 12. 1391 1392 void lodepng_chunk_type(char type[5], const unsigned char* chunk): 1393 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type): 1394 1395 Get the type of the chunk or compare if it's a certain type 1396 1397 unsigned char lodepng_chunk_critical(const unsigned char* chunk): 1398 unsigned char lodepng_chunk_private(const unsigned char* chunk): 1399 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk): 1400 1401 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are). 1402 Check if the chunk is private (public chunks are part of the standard, private ones not). 1403 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical 1404 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your 1405 program doesn't handle that type of unknown chunk. 1406 1407 unsigned char* lodepng_chunk_data(unsigned char* chunk): 1408 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk): 1409 1410 Get a pointer to the start of the data of the chunk. 1411 1412 unsigned lodepng_chunk_check_crc(const unsigned char* chunk): 1413 void lodepng_chunk_generate_crc(unsigned char* chunk): 1414 1415 Check if the crc is correct or generate a correct one. 1416 1417 unsigned char* lodepng_chunk_next(unsigned char* chunk): 1418 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk): 1419 1420 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these 1421 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough 1422 data available in the buffer to be able to go to the next chunk. 1423 1424 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk): 1425 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 1426 const char* type, const unsigned char* data): 1427 1428 These functions are used to create new chunks that are appended to the data in *out that has 1429 length *outlength. The append function appends an existing chunk to the new data. The create 1430 function creates a new chunk with the given parameters and appends it. Type is the 4-letter 1431 name of the chunk. 1432 1433 8.2. chunks in info_png 1434 ----------------------- 1435 1436 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3 1437 buffers (each with size) to contain 3 types of unknown chunks: 1438 the ones that come before the PLTE chunk, the ones that come between the PLTE 1439 and the IDAT chunks, and the ones that come after the IDAT chunks. 1440 It's necessary to make the distionction between these 3 cases because the PNG 1441 standard forces to keep the ordering of unknown chunks compared to the critical 1442 chunks, but does not force any other ordering rules. 1443 1444 info_png.unknown_chunks_data[0] is the chunks before PLTE 1445 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT 1446 info_png.unknown_chunks_data[2] is the chunks after IDAT 1447 1448 The chunks in these 3 buffers can be iterated through and read by using the same 1449 way described in the previous subchapter. 1450 1451 When using the decoder to decode a PNG, you can make it store all unknown chunks 1452 if you set the option settings.remember_unknown_chunks to 1. By default, this 1453 option is off (0). 1454 1455 The encoder will always encode unknown chunks that are stored in the info_png. 1456 If you need it to add a particular chunk that isn't known by LodePNG, you can 1457 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in 1458 info_png.unknown_chunks_data[x]. 1459 1460 Chunks that are known by LodePNG should not be added in that way. E.g. to make 1461 LodePNG add a bKGD chunk, set background_defined to true and add the correct 1462 parameters there instead. 1463 1464 1465 9. compiler support 1466 ------------------- 1467 1468 No libraries other than the current standard C library are needed to compile 1469 LodePNG. For the C++ version, only the standard C++ library is needed on top. 1470 Add the files lodepng.c(pp) and lodepng.h to your project, include 1471 lodepng.h where needed, and your program can read/write PNG files. 1472 1473 It is compatible with C90 and up, and C++03 and up. 1474 1475 If performance is important, use optimization when compiling! For both the 1476 encoder and decoder, this makes a large difference. 1477 1478 Make sure that LodePNG is compiled with the same compiler of the same version 1479 and with the same settings as the rest of the program, or the interfaces with 1480 std::vectors and std::strings in C++ can be incompatible. 1481 1482 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets. 1483 1484 *) gcc and g++ 1485 1486 LodePNG is developed in gcc so this compiler is natively supported. It gives no 1487 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++ 1488 version 4.7.1 on Linux, 32-bit and 64-bit. 1489 1490 *) Clang 1491 1492 Fully supported and warning-free. 1493 1494 *) Mingw 1495 1496 The Mingw compiler (a port of gcc for Windows) should be fully supported by 1497 LodePNG. 1498 1499 *) Visual Studio and Visual C++ Express Edition 1500 1501 LodePNG should be warning-free with warning level W4. Two warnings were disabled 1502 with pragmas though: warning 4244 about implicit conversions, and warning 4996 1503 where it wants to use a non-standard function fopen_s instead of the standard C 1504 fopen. 1505 1506 Visual Studio may want "stdafx.h" files to be included in each source file and 1507 give an error "unexpected end of file while looking for precompiled header". 1508 This is not standard C++ and will not be added to the stock LodePNG. You can 1509 disable it for lodepng.cpp only by right clicking it, Properties, C/C++, 1510 Precompiled Headers, and set it to Not Using Precompiled Headers there. 1511 1512 NOTE: Modern versions of VS should be fully supported, but old versions, e.g. 1513 VS6, are not guaranteed to work. 1514 1515 *) Compilers on Macintosh 1516 1517 LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for 1518 C and C++. 1519 1520 *) Other Compilers 1521 1522 If you encounter problems on any compilers, feel free to let me know and I may 1523 try to fix it if the compiler is modern and standards compliant. 1524 1525 1526 10. examples 1527 ------------ 1528 1529 This decoder example shows the most basic usage of LodePNG. More complex 1530 examples can be found on the LodePNG website. 1531 1532 10.1. decoder C++ example 1533 ------------------------- 1534 1535 #include "lodepng.h" 1536 #include <iostream> 1537 1538 int main(int argc, char *argv[]) 1539 { 1540 const char* filename = argc > 1 ? argv[1] : "test.png"; 1541 1542 //load and decode 1543 std::vector<unsigned char> image; 1544 unsigned width, height; 1545 unsigned error = lodepng::decode(image, width, height, filename); 1546 1547 //if there's an error, display it 1548 if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl; 1549 1550 //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ... 1551 } 1552 1553 10.2. decoder C example 1554 ----------------------- 1555 1556 #include "lodepng.h" 1557 1558 int main(int argc, char *argv[]) 1559 { 1560 unsigned error; 1561 unsigned char* image; 1562 size_t width, height; 1563 const char* filename = argc > 1 ? argv[1] : "test.png"; 1564 1565 error = lodepng_decode32_file(&image, &width, &height, filename); 1566 1567 if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error)); 1568 1569 / * use image here * / 1570 1571 free(image); 1572 return 0; 1573 } 1574 1575 11. state settings reference 1576 ---------------------------- 1577 1578 A quick reference of some settings to set on the LodePNGState 1579 1580 For decoding: 1581 1582 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums 1583 state.decoder.zlibsettings.custom_...: use custom inflate function 1584 state.decoder.ignore_crc: ignore CRC checksums 1585 state.decoder.color_convert: convert internal PNG color to chosen one 1586 state.decoder.read_text_chunks: whether to read in text metadata chunks 1587 state.decoder.remember_unknown_chunks: whether to read in unknown chunks 1588 state.info_raw.colortype: desired color type for decoded image 1589 state.info_raw.bitdepth: desired bit depth for decoded image 1590 state.info_raw....: more color settings, see struct LodePNGColorMode 1591 state.info_png....: no settings for decoder but output, see struct LodePNGInfo 1592 1593 For encoding: 1594 1595 state.encoder.zlibsettings.btype: disable compression by setting it to 0 1596 state.encoder.zlibsettings.use_lz77: use LZ77 in compression 1597 state.encoder.zlibsettings.windowsize: tweak LZ77 windowsize 1598 state.encoder.zlibsettings.minmatch: tweak min LZ77 length to match 1599 state.encoder.zlibsettings.nicematch: tweak LZ77 match where to stop searching 1600 state.encoder.zlibsettings.lazymatching: try one more LZ77 matching 1601 state.encoder.zlibsettings.custom_...: use custom deflate function 1602 state.encoder.auto_convert: choose optimal PNG color type, if 0 uses info_png 1603 state.encoder.filter_palette_zero: PNG filter strategy for palette 1604 state.encoder.filter_strategy: PNG filter strategy to encode with 1605 state.encoder.force_palette: add palette even if not encoding to one 1606 state.encoder.add_id: add LodePNG identifier and version as a text chunk 1607 state.encoder.text_compression: use compressed text chunks for metadata 1608 state.info_raw.colortype: color type of raw input image you provide 1609 state.info_raw.bitdepth: bit depth of raw input image you provide 1610 state.info_raw: more color settings, see struct LodePNGColorMode 1611 state.info_png.color.colortype: desired color type if auto_convert is false 1612 state.info_png.color.bitdepth: desired bit depth if auto_convert is false 1613 state.info_png.color....: more color settings, see struct LodePNGColorMode 1614 state.info_png....: more PNG related settings, see struct LodePNGInfo 1615 1616 1617 12. changes 1618 ----------- 1619 1620 The version number of LodePNG is the date of the change given in the format 1621 yyyymmdd. 1622 1623 Some changes aren't backwards compatible. Those are indicated with a (!) 1624 symbol. 1625 1626 *) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within 1627 the limits of pure C90). 1628 *) 08 dec 2015: Made load_file function return error if file can't be opened. 1629 *) 24 okt 2015: Bugfix with decoding to palette output. 1630 *) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding. 1631 *) 23 aug 2014: Reduced needless memory usage of decoder. 1632 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for 1633 simplicity. Made ColorProfile public. 1634 *) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization. 1635 *) 22 dec 2013: Power of two windowsize required for optimization. 1636 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key. 1637 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png). 1638 *) 11 mar 2013 (!): Bugfix with custom free. Changed from "my" to "lodepng_" 1639 prefix for the custom allocators and made it possible with a new #define to 1640 use custom ones in your project without needing to change lodepng's code. 1641 *) 28 jan 2013: Bugfix with color key. 1642 *) 27 okt 2012: Tweaks in text chunk keyword length error handling. 1643 *) 8 okt 2012 (!): Added new filter strategy (entropy) and new auto color mode. 1644 (no palette). Better deflate tree encoding. New compression tweak settings. 1645 Faster color conversions while decoding. Some internal cleanups. 1646 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit. 1647 *) 1 sep 2012 (!): Removed #define's for giving custom (de)compression functions 1648 and made it work with function pointers instead. 1649 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc 1650 and free functions and toggle #defines from compiler flags. Small fixes. 1651 *) 6 may 2012 (!): Made plugging in custom zlib/deflate functions more flexible. 1652 *) 22 apr 2012 (!): Made interface more consistent, renaming a lot. Removed 1653 redundant C++ codec classes. Reduced amount of structs. Everything changed, 1654 but it is cleaner now imho and functionality remains the same. Also fixed 1655 several bugs and shrunk the implementation code. Made new samples. 1656 *) 6 nov 2011 (!): By default, the encoder now automatically chooses the best 1657 PNG color model and bit depth, based on the amount and type of colors of the 1658 raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color. 1659 *) 9 okt 2011: simpler hash chain implementation for the encoder. 1660 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching. 1661 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking. 1662 A bug with the PNG filtertype heuristic was fixed, so that it chooses much 1663 better ones (it's quite significant). A setting to do an experimental, slow, 1664 brute force search for PNG filter types is added. 1665 *) 17 aug 2011 (!): changed some C zlib related function names. 1666 *) 16 aug 2011: made the code less wide (max 120 characters per line). 1667 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors. 1668 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled. 1669 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman 1670 to optimize long sequences of zeros. 1671 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and 1672 LodePNG_InfoColor_canHaveAlpha functions for convenience. 1673 *) 7 nov 2010: added LodePNG_error_text function to get error code description. 1674 *) 30 okt 2010: made decoding slightly faster 1675 *) 26 okt 2010: (!) changed some C function and struct names (more consistent). 1676 Reorganized the documentation and the declaration order in the header. 1677 *) 08 aug 2010: only changed some comments and external samples. 1678 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version. 1679 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers. 1680 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could 1681 read by ignoring the problem but windows apps couldn't. 1682 *) 06 jun 2008: added more error checks for out of memory cases. 1683 *) 26 apr 2008: added a few more checks here and there to ensure more safety. 1684 *) 06 mar 2008: crash with encoding of strings fixed 1685 *) 02 feb 2008: support for international text chunks added (iTXt) 1686 *) 23 jan 2008: small cleanups, and #defines to divide code in sections 1687 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor. 1688 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder. 1689 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added 1690 Also various fixes, such as in the deflate and the padding bits code. 1691 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved 1692 filtering code of encoder. 1693 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A 1694 C++ wrapper around this provides an interface almost identical to before. 1695 Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code 1696 are together in these files but it works both for C and C++ compilers. 1697 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks 1698 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible 1699 *) 09 aug 2007: some VS2005 warnings removed again 1700 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code 1701 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images 1702 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing 1703 invalid std::vector element [0] fixed, and level 3 and 4 warnings removed 1704 *) 02 jun 2007: made the encoder add a tag with version by default 1705 *) 27 may 2007: zlib and png code separated (but still in the same file), 1706 simple encoder/decoder functions added for more simple usage cases 1707 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69), 1708 moved some examples from here to lodepng_examples.cpp 1709 *) 12 may 2007: palette decoding bug fixed 1710 *) 24 apr 2007: changed the license from BSD to the zlib license 1711 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks. 1712 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding 1713 palettized PNG images. Plus little interface change with palette and texts. 1714 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes. 1715 Fixed a bug where the end code of a block had length 0 in the Huffman tree. 1716 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented 1717 and supported by the encoder, resulting in smaller PNGs at the output. 1718 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone. 1719 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any 1720 greyscale type to 8-bit greyscale with or without alpha. 1721 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types 1722 to convert to and is more uniform. See the manual for how it works now. 1723 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days: 1724 encode/decode custom tEXt chunks, separate classes for zlib & deflate, and 1725 at last made the decoder give errors for incorrect Adler32 or Crc. 1726 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel. 1727 *) 29 dec 2006: Added support for encoding images without alpha channel, and 1728 cleaned out code as well as making certain parts faster. 1729 *) 28 dec 2006: Added "Settings" to the encoder. 1730 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now. 1731 Removed some code duplication in the decoder. Fixed little bug in an example. 1732 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter. 1733 Fixed a bug of the decoder with 16-bit per color. 1734 *) 15 okt 2006: Changed documentation structure 1735 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the 1736 given image buffer, however for now it's not compressed. 1737 *) 08 sep 2006: (!) Changed to interface with a Decoder class 1738 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different 1739 way. Renamed decodePNG to decodePNGGeneric. 1740 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a 1741 struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy. 1742 *) 28 jul 2006: Cleaned the code and added new error checks. 1743 Corrected terminology "deflate" into "inflate". 1744 *) 23 jun 2006: Added SDL example in the documentation in the header, this 1745 example allows easy debugging by displaying the PNG and its transparency. 1746 *) 22 jun 2006: (!) Changed way to obtain error value. Added 1747 loadFile function for convenience. Made decodePNG32 faster. 1748 *) 21 jun 2006: (!) Changed type of info vector to unsigned. 1749 Changed position of palette in info vector. Fixed an important bug that 1750 happened on PNGs with an uncompressed block. 1751 *) 16 jun 2006: Internally changed unsigned into unsigned where 1752 needed, and performed some optimizations. 1753 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them 1754 in LodePNG namespace. Changed the order of the parameters. Rewrote the 1755 documentation in the header. Renamed files to lodepng.cpp and lodepng.h 1756 *) 22 apr 2006: Optimized and improved some code 1757 *) 07 sep 2005: (!) Changed to std::vector interface 1758 *) 12 aug 2005: Initial release (C++, decoder only) 1759 1760 1761 13. contact information 1762 ----------------------- 1763 1764 Feel free to contact me with suggestions, problems, comments, ... concerning 1765 LodePNG. If you encounter a PNG image that doesn't work properly with this 1766 decoder, feel free to send it and I'll use it to find and fix the problem. 1767 1768 My email address is (puzzle the account and domain together with an @ symbol): 1769 Domain: gmail dot com. 1770 Account: lode dot vandevenne. 1771 1772 1773 Copyright (c) 2005-2016 Lode Vandevenne 1774 */ 1775