1 /* 2 LodePNG version 20131222 3 4 Copyright (c) 2005-2013 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 /*Compile the default allocators (C's free, malloc and realloc). If you disable this, 73 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your 74 source files with custom allocators.*/ 75 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS 76 #define LODEPNG_COMPILE_ALLOCATORS 77 #endif 78 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/ 79 #ifdef __cplusplus 80 #ifndef LODEPNG_NO_COMPILE_CPP 81 #define LODEPNG_COMPILE_CPP 82 #endif 83 #endif 84 85 #ifdef LODEPNG_COMPILE_PNG 86 /*The PNG color types (also used for raw).*/ 87 typedef enum LodePNGColorType 88 { 89 LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/ 90 LCT_RGB = 2, /*RGB: 8,16 bit*/ 91 LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/ 92 LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/ 93 LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/ 94 } LodePNGColorType; 95 96 #ifdef LODEPNG_COMPILE_DECODER 97 /* 98 Converts PNG data in memory to raw pixel data. 99 out: Output parameter. Pointer to buffer that will contain the raw pixel data. 100 After decoding, its size is w * h * (bytes per pixel) bytes larger than 101 initially. Bytes per pixel depends on colortype and bitdepth. 102 Must be freed after usage with free(*out). 103 Note: for 16-bit per channel colors, uses big endian format like PNG does. 104 w: Output parameter. Pointer to width of pixel data. 105 h: Output parameter. Pointer to height of pixel data. 106 in: Memory buffer with the PNG file. 107 insize: size of the in buffer. 108 colortype: the desired color type for the raw output image. See explanation on PNG color types. 109 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types. 110 Return value: LodePNG error code (0 means no error). 111 */ 112 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, 113 const unsigned char* in, size_t insize, 114 LodePNGColorType colortype, unsigned bitdepth); 115 116 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/ 117 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, 118 const unsigned char* in, size_t insize); 119 120 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/ 121 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, 122 const unsigned char* in, size_t insize); 123 124 #ifdef LODEPNG_COMPILE_DISK 125 /* 126 Load PNG from disk, from file with given name. 127 Same as the other decode functions, but instead takes a filename as input. 128 */ 129 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, 130 const char* filename, 131 LodePNGColorType colortype, unsigned bitdepth); 132 133 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.*/ 134 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, 135 const char* filename); 136 137 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.*/ 138 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, 139 const char* filename); 140 #endif /*LODEPNG_COMPILE_DISK*/ 141 #endif /*LODEPNG_COMPILE_DECODER*/ 142 143 144 #ifdef LODEPNG_COMPILE_ENCODER 145 /* 146 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth 147 of the output PNG image cannot be chosen, they are automatically determined 148 by the colortype, bitdepth and content of the input pixel data. 149 Note: for 16-bit per channel colors, needs big endian format like PNG does. 150 out: Output parameter. Pointer to buffer that will contain the PNG image data. 151 Must be freed after usage with free(*out). 152 outsize: Output parameter. Pointer to the size in bytes of the out buffer. 153 image: The raw pixel data to encode. The size of this buffer should be 154 w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth. 155 w: width of the raw pixel data in pixels. 156 h: height of the raw pixel data in pixels. 157 colortype: the color type of the raw input image. See explanation on PNG color types. 158 bitdepth: the bit depth of the raw input image. See explanation on PNG color types. 159 Return value: LodePNG error code (0 means no error). 160 */ 161 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, 162 const unsigned char* image, unsigned w, unsigned h, 163 LodePNGColorType colortype, unsigned bitdepth); 164 165 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/ 166 unsigned lodepng_encode32(unsigned char** out, size_t* outsize, 167 const unsigned char* image, unsigned w, unsigned h); 168 169 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/ 170 unsigned lodepng_encode24(unsigned char** out, size_t* outsize, 171 const unsigned char* image, unsigned w, unsigned h); 172 173 #ifdef LODEPNG_COMPILE_DISK 174 /* 175 Converts raw pixel data into a PNG file on disk. 176 Same as the other encode functions, but instead takes a filename as output. 177 NOTE: This overwrites existing files without warning! 178 */ 179 unsigned lodepng_encode_file(const char* filename, 180 const unsigned char* image, unsigned w, unsigned h, 181 LodePNGColorType colortype, unsigned bitdepth); 182 183 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.*/ 184 unsigned lodepng_encode32_file(const char* filename, 185 const unsigned char* image, unsigned w, unsigned h); 186 187 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.*/ 188 unsigned lodepng_encode24_file(const char* filename, 189 const unsigned char* image, unsigned w, unsigned h); 190 #endif /*LODEPNG_COMPILE_DISK*/ 191 #endif /*LODEPNG_COMPILE_ENCODER*/ 192 193 194 #ifdef LODEPNG_COMPILE_CPP 195 namespace lodepng 196 { 197 #ifdef LODEPNG_COMPILE_DECODER 198 /*Same as lodepng_decode_memory, but decodes to an std::vector.*/ 199 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 200 const unsigned char* in, size_t insize, 201 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 202 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 203 const std::vector<unsigned char>& in, 204 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 205 #ifdef LODEPNG_COMPILE_DISK 206 /* 207 Converts PNG file from disk to raw pixel data in memory. 208 Same as the other decode functions, but instead takes a filename as input. 209 */ 210 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 211 const std::string& filename, 212 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 213 #endif //LODEPNG_COMPILE_DISK 214 #endif //LODEPNG_COMPILE_DECODER 215 216 #ifdef LODEPNG_COMPILE_ENCODER 217 /*Same as lodepng_encode_memory, but encodes to an std::vector.*/ 218 unsigned encode(std::vector<unsigned char>& out, 219 const unsigned char* in, unsigned w, unsigned h, 220 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 221 unsigned encode(std::vector<unsigned char>& out, 222 const std::vector<unsigned char>& in, unsigned w, unsigned h, 223 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 224 #ifdef LODEPNG_COMPILE_DISK 225 /* 226 Converts 32-bit RGBA raw pixel data into a PNG file on disk. 227 Same as the other encode functions, but instead takes a filename as output. 228 NOTE: This overwrites existing files without warning! 229 */ 230 unsigned encode(const std::string& filename, 231 const unsigned char* in, unsigned w, unsigned h, 232 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 233 unsigned encode(const std::string& filename, 234 const std::vector<unsigned char>& in, unsigned w, unsigned h, 235 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); 236 #endif //LODEPNG_COMPILE_DISK 237 #endif //LODEPNG_COMPILE_ENCODER 238 } //namespace lodepng 239 #endif /*LODEPNG_COMPILE_CPP*/ 240 #endif /*LODEPNG_COMPILE_PNG*/ 241 242 #ifdef LODEPNG_COMPILE_ERROR_TEXT 243 /*Returns an English description of the numerical error code.*/ 244 const char* lodepng_error_text(unsigned code); 245 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/ 246 247 #ifdef LODEPNG_COMPILE_DECODER 248 /*Settings for zlib decompression*/ 249 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; 250 struct LodePNGDecompressSettings 251 { 252 unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ 253 254 /*use custom zlib decoder instead of built in one (default: null)*/ 255 unsigned (*custom_zlib)(unsigned char**, size_t*, 256 const unsigned char*, size_t, 257 const LodePNGDecompressSettings*); 258 /*use custom deflate decoder instead of built in one (default: null) 259 if custom_zlib is used, custom_deflate is ignored since only the built in 260 zlib function will call custom_deflate*/ 261 unsigned (*custom_inflate)(unsigned char**, size_t*, 262 const unsigned char*, size_t, 263 const LodePNGDecompressSettings*); 264 265 const void* custom_context; /*optional custom settings for custom functions*/ 266 }; 267 268 extern const LodePNGDecompressSettings lodepng_default_decompress_settings; 269 void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings); 270 #endif /*LODEPNG_COMPILE_DECODER*/ 271 272 #ifdef LODEPNG_COMPILE_ENCODER 273 /* 274 Settings for zlib compression. Tweaking these settings tweaks the balance 275 between speed and compression ratio. 276 */ 277 typedef struct LodePNGCompressSettings LodePNGCompressSettings; 278 struct LodePNGCompressSettings /*deflate = compress*/ 279 { 280 /*LZ77 related settings*/ 281 unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/ 282 unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ 283 unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Typical value: 2048.*/ 284 unsigned minmatch; /*mininum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ 285 unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/ 286 unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ 287 288 /*use custom zlib encoder instead of built in one (default: null)*/ 289 unsigned (*custom_zlib)(unsigned char**, size_t*, 290 const unsigned char*, size_t, 291 const LodePNGCompressSettings*); 292 /*use custom deflate encoder instead of built in one (default: null) 293 if custom_zlib is used, custom_deflate is ignored since only the built in 294 zlib function will call custom_deflate*/ 295 unsigned (*custom_deflate)(unsigned char**, size_t*, 296 const unsigned char*, size_t, 297 const LodePNGCompressSettings*); 298 299 const void* custom_context; /*optional custom settings for custom functions*/ 300 }; 301 302 extern const LodePNGCompressSettings lodepng_default_compress_settings; 303 void lodepng_compress_settings_init(LodePNGCompressSettings* settings); 304 #endif /*LODEPNG_COMPILE_ENCODER*/ 305 306 #ifdef LODEPNG_COMPILE_PNG 307 /* 308 Color mode of an image. Contains all information required to decode the pixel 309 bits to RGBA colors. This information is the same as used in the PNG file 310 format, and is used both for PNG and raw image data in LodePNG. 311 */ 312 typedef struct LodePNGColorMode 313 { 314 /*header (IHDR)*/ 315 LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/ 316 unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ 317 318 /* 319 palette (PLTE and tRNS) 320 321 Dynamically allocated with the colors of the palette, including alpha. 322 When encoding a PNG, to store your colors in the palette of the LodePNGColorMode, first use 323 lodepng_palette_clear, then for each color use lodepng_palette_add. 324 If you encode an image without alpha with palette, don't forget to put value 255 in each A byte of the palette. 325 326 When decoding, by default you can ignore this palette, since LodePNG already 327 fills the palette colors in the pixels of the raw RGBA output. 328 329 The palette is only supported for color type 3. 330 */ 331 unsigned char* palette; /*palette in RGBARGBA... order. When allocated, must be either 0, or have size 1024*/ 332 size_t palettesize; /*palette size in number of colors (amount of bytes is 4 * palettesize)*/ 333 334 /* 335 transparent color key (tRNS) 336 337 This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit. 338 For greyscale PNGs, r, g and b will all 3 be set to the same. 339 340 When decoding, by default you can ignore this information, since LodePNG sets 341 pixels with this key to transparent already in the raw RGBA output. 342 343 The color key is only supported for color types 0 and 2. 344 */ 345 unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ 346 unsigned key_r; /*red/greyscale component of color key*/ 347 unsigned key_g; /*green component of color key*/ 348 unsigned key_b; /*blue component of color key*/ 349 } LodePNGColorMode; 350 351 /*init, cleanup and copy functions to use with this struct*/ 352 void lodepng_color_mode_init(LodePNGColorMode* info); 353 void lodepng_color_mode_cleanup(LodePNGColorMode* info); 354 /*return value is error code (0 means no error)*/ 355 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source); 356 357 void lodepng_palette_clear(LodePNGColorMode* info); 358 /*add 1 color to the palette*/ 359 unsigned lodepng_palette_add(LodePNGColorMode* info, 360 unsigned char r, unsigned char g, unsigned char b, unsigned char a); 361 362 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ 363 unsigned lodepng_get_bpp(const LodePNGColorMode* info); 364 /*get the amount of color channels used, based on colortype in the struct. 365 If a palette is used, it counts as 1 channel.*/ 366 unsigned lodepng_get_channels(const LodePNGColorMode* info); 367 /*is it a greyscale type? (only colortype 0 or 4)*/ 368 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info); 369 /*has it got an alpha channel? (only colortype 2 or 6)*/ 370 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info); 371 /*has it got a palette? (only colortype 3)*/ 372 unsigned lodepng_is_palette_type(const LodePNGColorMode* info); 373 /*only returns true if there is a palette and there is a value in the palette with alpha < 255. 374 Loops through the palette to check this.*/ 375 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info); 376 /* 377 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image. 378 Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels). 379 Returns false if the image can only have opaque pixels. 380 In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values, 381 or if "key_defined" is true. 382 */ 383 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info); 384 /*Returns the byte size of a raw image buffer with given width, height and color mode*/ 385 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color); 386 387 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 388 /*The information of a Time chunk in PNG.*/ 389 typedef struct LodePNGTime 390 { 391 unsigned year; /*2 bytes used (0-65535)*/ 392 unsigned month; /*1-12*/ 393 unsigned day; /*1-31*/ 394 unsigned hour; /*0-23*/ 395 unsigned minute; /*0-59*/ 396 unsigned second; /*0-60 (to allow for leap seconds)*/ 397 } LodePNGTime; 398 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 399 400 /*Information about the PNG image, except pixels, width and height.*/ 401 typedef struct LodePNGInfo 402 { 403 /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ 404 unsigned compression_method;/*compression method of the original file. Always 0.*/ 405 unsigned filter_method; /*filter method of the original file*/ 406 unsigned interlace_method; /*interlace method of the original file*/ 407 LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/ 408 409 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 410 /* 411 suggested background color chunk (bKGD) 412 This color uses the same color mode as the PNG (except alpha channel), which can be 1-bit to 16-bit. 413 414 For greyscale PNGs, r, g and b will all 3 be set to the same. When encoding 415 the encoder writes the red one. For palette PNGs: When decoding, the RGB value 416 will be stored, not a palette index. But when encoding, specify the index of 417 the palette in background_r, the other two are then ignored. 418 419 The decoder does not use this background color to edit the color of pixels. 420 */ 421 unsigned background_defined; /*is a suggested background color given?*/ 422 unsigned background_r; /*red component of suggested background color*/ 423 unsigned background_g; /*green component of suggested background color*/ 424 unsigned background_b; /*blue component of suggested background color*/ 425 426 /* 427 non-international text chunks (tEXt and zTXt) 428 429 The char** arrays each contain num strings. The actual messages are in 430 text_strings, while text_keys are keywords that give a short description what 431 the actual text represents, e.g. Title, Author, Description, or anything else. 432 433 A keyword is minimum 1 character and maximum 79 characters long. It's 434 discouraged to use a single line length longer than 79 characters for texts. 435 436 Don't allocate these text buffers yourself. Use the init/cleanup functions 437 correctly and use lodepng_add_text and lodepng_clear_text. 438 */ 439 size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/ 440 char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/ 441 char** text_strings; /*the actual text*/ 442 443 /* 444 international text chunks (iTXt) 445 Similar to the non-international text chunks, but with additional strings 446 "langtags" and "transkeys". 447 */ 448 size_t itext_num; /*the amount of international texts in this PNG*/ 449 char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ 450 char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/ 451 char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/ 452 char** itext_strings; /*the actual international text - UTF-8 string*/ 453 454 /*time chunk (tIME)*/ 455 unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ 456 LodePNGTime time; 457 458 /*phys chunk (pHYs)*/ 459 unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/ 460 unsigned phys_x; /*pixels per unit in x direction*/ 461 unsigned phys_y; /*pixels per unit in y direction*/ 462 unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ 463 464 /* 465 unknown chunks 466 There are 3 buffers, one for each position in the PNG where unknown chunks can appear 467 each buffer contains all unknown chunks for that position consecutively 468 The 3 buffers are the unknown chunks between certain critical chunks: 469 0: IHDR-PLTE, 1: PLTE-IDAT, 2: IDAT-IEND 470 Do not allocate or traverse this data yourself. Use the chunk traversing functions declared 471 later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct. 472 */ 473 unsigned char* unknown_chunks_data[3]; 474 size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ 475 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 476 } LodePNGInfo; 477 478 /*init, cleanup and copy functions to use with this struct*/ 479 void lodepng_info_init(LodePNGInfo* info); 480 void lodepng_info_cleanup(LodePNGInfo* info); 481 /*return value is error code (0 means no error)*/ 482 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source); 483 484 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 485 void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ 486 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/ 487 488 void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ 489 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag, 490 const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/ 491 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 492 493 /* 494 Converts raw buffer from one color type to another color type, based on 495 LodePNGColorMode structs to describe the input and output color type. 496 See the reference manual at the end of this header file to see which color conversions are supported. 497 return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported) 498 The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel 499 of the output color type (lodepng_get_bpp) 500 The fix_png value works as described in struct LodePNGDecoderSettings. 501 Note: for 16-bit per channel colors, uses big endian format like PNG does. 502 */ 503 unsigned lodepng_convert(unsigned char* out, const unsigned char* in, 504 LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in, 505 unsigned w, unsigned h, unsigned fix_png); 506 507 #ifdef LODEPNG_COMPILE_DECODER 508 /* 509 Settings for the decoder. This contains settings for the PNG and the Zlib 510 decoder, but not the Info settings from the Info structs. 511 */ 512 typedef struct LodePNGDecoderSettings 513 { 514 LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ 515 516 unsigned ignore_crc; /*ignore CRC checksums*/ 517 /* 518 The fix_png setting, if 1, makes the decoder tolerant towards some PNG images 519 that do not correctly follow the PNG specification. This only supports errors 520 that are fixable, were found in images that are actually used on the web, and 521 are silently tolerated by other decoders as well. Currently only one such fix 522 is implemented: if a palette index is out of bounds given the palette size, 523 interpret it as opaque black. 524 By default this value is 0, which makes it stop with an error on such images. 525 */ 526 unsigned fix_png; 527 unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ 528 529 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 530 unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/ 531 /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/ 532 unsigned remember_unknown_chunks; 533 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 534 } LodePNGDecoderSettings; 535 536 void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); 537 #endif /*LODEPNG_COMPILE_DECODER*/ 538 539 #ifdef LODEPNG_COMPILE_ENCODER 540 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ 541 typedef enum LodePNGFilterStrategy 542 { 543 /*every filter at zero*/ 544 LFS_ZERO, 545 /*Use filter that gives minumum sum, as described in the official PNG filter heuristic.*/ 546 LFS_MINSUM, 547 /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending 548 on the image, this is better or worse than minsum.*/ 549 LFS_ENTROPY, 550 /* 551 Brute-force-search PNG filters by compressing each filter for each scanline. 552 Experimental, very slow, and only rarely gives better compression than MINSUM. 553 */ 554 LFS_BRUTE_FORCE, 555 /*use predefined_filters buffer: you specify the filter type for each scanline*/ 556 LFS_PREDEFINED 557 } LodePNGFilterStrategy; 558 559 /*automatically use color type with less bits per pixel if losslessly possible. Default: LAC_AUTO*/ 560 typedef enum LodePNGAutoConvert 561 { 562 LAC_NO, /*use color type user requested*/ 563 LAC_ALPHA, /*use color type user requested, but if only opaque pixels and RGBA or grey+alpha, use RGB or grey*/ 564 LAC_AUTO, /*use PNG color type that can losslessly represent the uncompressed image the smallest possible*/ 565 /* 566 like AUTO, but do not choose 1, 2 or 4 bit per pixel types. 567 sometimes a PNG image compresses worse if less than 8 bits per pixels. 568 */ 569 LAC_AUTO_NO_NIBBLES, 570 /* 571 like AUTO, but never choose palette color type. For small images, encoding 572 the palette may take more bytes than what is gained. Note that AUTO also 573 already prevents encoding the palette for extremely small images, but that may 574 not be sufficient because due to the compression it cannot predict when to 575 switch. 576 */ 577 LAC_AUTO_NO_PALETTE, 578 LAC_AUTO_NO_NIBBLES_NO_PALETTE 579 } LodePNGAutoConvert; 580 581 582 /* 583 Automatically chooses color type that gives smallest amount of bits in the 584 output image, e.g. grey if there are only greyscale pixels, palette if there 585 are less than 256 colors, ... 586 The auto_convert parameter allows limiting it to not use palette, ... 587 */ 588 unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out, 589 const unsigned char* image, unsigned w, unsigned h, 590 const LodePNGColorMode* mode_in, 591 LodePNGAutoConvert auto_convert); 592 593 /*Settings for the encoder.*/ 594 typedef struct LodePNGEncoderSettings 595 { 596 LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ 597 598 LodePNGAutoConvert auto_convert; /*how to automatically choose output PNG color type, if at all*/ 599 600 /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than 601 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to 602 completely follow the official PNG heuristic, filter_palette_zero must be true and 603 filter_strategy must be LFS_MINSUM*/ 604 unsigned filter_palette_zero; 605 /*Which filter strategy to use when not using zeroes due to filter_palette_zero. 606 Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/ 607 LodePNGFilterStrategy filter_strategy; 608 /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with 609 the same length as the amount of scanlines in the image, and each value must <= 5. You 610 have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero 611 must be set to 0 to ensure this is also used on palette or low bitdepth images.*/ 612 const unsigned char* predefined_filters; 613 614 /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). 615 If colortype is 3, PLTE is _always_ created.*/ 616 unsigned force_palette; 617 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS 618 /*add LodePNG identifier and version as a text chunk, for debugging*/ 619 unsigned add_id; 620 /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ 621 unsigned text_compression; 622 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ 623 } LodePNGEncoderSettings; 624 625 void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); 626 #endif /*LODEPNG_COMPILE_ENCODER*/ 627 628 629 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) 630 /*The settings, state and information for extended encoding and decoding.*/ 631 typedef struct LodePNGState 632 { 633 #ifdef LODEPNG_COMPILE_DECODER 634 LodePNGDecoderSettings decoder; /*the decoding settings*/ 635 #endif /*LODEPNG_COMPILE_DECODER*/ 636 #ifdef LODEPNG_COMPILE_ENCODER 637 LodePNGEncoderSettings encoder; /*the encoding settings*/ 638 #endif /*LODEPNG_COMPILE_ENCODER*/ 639 LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ 640 LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/ 641 unsigned error; 642 #ifdef LODEPNG_COMPILE_CPP 643 //For the lodepng::State subclass. 644 virtual ~LodePNGState(){} 645 #endif 646 } LodePNGState; 647 648 /*init, cleanup and copy functions to use with this struct*/ 649 void lodepng_state_init(LodePNGState* state); 650 void lodepng_state_cleanup(LodePNGState* state); 651 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source); 652 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */ 653 654 #ifdef LODEPNG_COMPILE_DECODER 655 /* 656 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and 657 getting much more information about the PNG image and color mode. 658 */ 659 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, 660 LodePNGState* state, 661 const unsigned char* in, size_t insize); 662 663 /* 664 Read the PNG header, but not the actual data. This returns only the information 665 that is in the header chunk of the PNG, such as width, height and color type. The 666 information is placed in the info_png field of the LodePNGState. 667 */ 668 unsigned lodepng_inspect(unsigned* w, unsigned* h, 669 LodePNGState* state, 670 const unsigned char* in, size_t insize); 671 #endif /*LODEPNG_COMPILE_DECODER*/ 672 673 674 #ifdef LODEPNG_COMPILE_ENCODER 675 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ 676 unsigned lodepng_encode(unsigned char** out, size_t* outsize, 677 const unsigned char* image, unsigned w, unsigned h, 678 LodePNGState* state); 679 #endif /*LODEPNG_COMPILE_ENCODER*/ 680 681 /* 682 The lodepng_chunk functions are normally not needed, except to traverse the 683 unknown chunks stored in the LodePNGInfo struct, or add new ones to it. 684 It also allows traversing the chunks of an encoded PNG file yourself. 685 686 PNG standard chunk naming conventions: 687 First byte: uppercase = critical, lowercase = ancillary 688 Second byte: uppercase = public, lowercase = private 689 Third byte: must be uppercase 690 Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy 691 */ 692 693 /*get the length of the data of the chunk. Total chunk length has 12 bytes more.*/ 694 unsigned lodepng_chunk_length(const unsigned char* chunk); 695 696 /*puts the 4-byte type in null terminated string*/ 697 void lodepng_chunk_type(char type[5], const unsigned char* chunk); 698 699 /*check if the type is the given type*/ 700 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type); 701 702 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ 703 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk); 704 705 /*0: public, 1: private (see PNG standard)*/ 706 unsigned char lodepng_chunk_private(const unsigned char* chunk); 707 708 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ 709 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk); 710 711 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/ 712 unsigned char* lodepng_chunk_data(unsigned char* chunk); 713 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk); 714 715 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ 716 unsigned lodepng_chunk_check_crc(const unsigned char* chunk); 717 718 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ 719 void lodepng_chunk_generate_crc(unsigned char* chunk); 720 721 /*iterate to next chunks. don't use on IEND chunk, as there is no next chunk then*/ 722 unsigned char* lodepng_chunk_next(unsigned char* chunk); 723 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk); 724 725 /* 726 Appends chunk to the data in out. The given chunk should already have its chunk header. 727 The out variable and outlength are updated to reflect the new reallocated buffer. 728 Returns error code (0 if it went ok) 729 */ 730 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk); 731 732 /* 733 Appends new chunk to out. The chunk to append is given by giving its length, type 734 and data separately. The type is a 4-letter string. 735 The out variable and outlength are updated to reflect the new reallocated buffer. 736 Returne error code (0 if it went ok) 737 */ 738 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 739 const char* type, const unsigned char* data); 740 741 742 /*Calculate CRC32 of buffer*/ 743 unsigned lodepng_crc32(const unsigned char* buf, size_t len); 744 #endif /*LODEPNG_COMPILE_PNG*/ 745 746 747 #ifdef LODEPNG_COMPILE_ZLIB 748 /* 749 This zlib part can be used independently to zlib compress and decompress a 750 buffer. It cannot be used to create gzip files however, and it only supports the 751 part of zlib that is required for PNG, it does not support dictionaries. 752 */ 753 754 #ifdef LODEPNG_COMPILE_DECODER 755 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/ 756 unsigned lodepng_inflate(unsigned char** out, size_t* outsize, 757 const unsigned char* in, size_t insize, 758 const LodePNGDecompressSettings* settings); 759 760 /* 761 Decompresses Zlib data. Reallocates the out buffer and appends the data. The 762 data must be according to the zlib specification. 763 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 764 buffer and *outsize its size in bytes. out must be freed by user after usage. 765 */ 766 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, 767 const unsigned char* in, size_t insize, 768 const LodePNGDecompressSettings* settings); 769 #endif /*LODEPNG_COMPILE_DECODER*/ 770 771 #ifdef LODEPNG_COMPILE_ENCODER 772 /* 773 Compresses data with Zlib. Reallocates the out buffer and appends the data. 774 Zlib adds a small header and trailer around the deflate data. 775 The data is output in the format of the zlib specification. 776 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid 777 buffer and *outsize its size in bytes. out must be freed by user after usage. 778 */ 779 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, 780 const unsigned char* in, size_t insize, 781 const LodePNGCompressSettings* settings); 782 783 /* 784 Find length-limited Huffman code for given frequencies. This function is in the 785 public interface only for tests, it's used internally by lodepng_deflate. 786 */ 787 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies, 788 size_t numcodes, unsigned maxbitlen); 789 790 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ 791 unsigned lodepng_deflate(unsigned char** out, size_t* outsize, 792 const unsigned char* in, size_t insize, 793 const LodePNGCompressSettings* settings); 794 795 #endif /*LODEPNG_COMPILE_ENCODER*/ 796 #endif /*LODEPNG_COMPILE_ZLIB*/ 797 798 #ifdef LODEPNG_COMPILE_DISK 799 /* 800 Load a file from disk into buffer. The function allocates the out buffer, and 801 after usage you should free it. 802 out: output parameter, contains pointer to loaded buffer. 803 outsize: output parameter, size of the allocated out buffer 804 filename: the path to the file to load 805 return value: error code (0 means ok) 806 */ 807 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename); 808 809 /* 810 Save a file from buffer to disk. Warning, if it exists, this function overwrites 811 the file without warning! 812 buffer: the buffer to write 813 buffersize: size of the buffer to write 814 filename: the path to the file to save to 815 return value: error code (0 means ok) 816 */ 817 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename); 818 #endif /*LODEPNG_COMPILE_DISK*/ 819 820 #ifdef LODEPNG_COMPILE_CPP 821 //The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. 822 namespace lodepng 823 { 824 #ifdef LODEPNG_COMPILE_PNG 825 class State : public LodePNGState 826 { 827 public: 828 State(); 829 State(const State& other); 830 virtual ~State(); 831 State& operator=(const State& other); 832 }; 833 834 #ifdef LODEPNG_COMPILE_DECODER 835 //Same as other lodepng::decode, but using a State for more settings and information. 836 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 837 State& state, 838 const unsigned char* in, size_t insize); 839 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, 840 State& state, 841 const std::vector<unsigned char>& in); 842 #endif /*LODEPNG_COMPILE_DECODER*/ 843 844 #ifdef LODEPNG_COMPILE_ENCODER 845 //Same as other lodepng::encode, but using a State for more settings and information. 846 unsigned encode(std::vector<unsigned char>& out, 847 const unsigned char* in, unsigned w, unsigned h, 848 State& state); 849 unsigned encode(std::vector<unsigned char>& out, 850 const std::vector<unsigned char>& in, unsigned w, unsigned h, 851 State& state); 852 #endif /*LODEPNG_COMPILE_ENCODER*/ 853 854 #ifdef LODEPNG_COMPILE_DISK 855 /* 856 Load a file from disk into an std::vector. If the vector is empty, then either 857 the file doesn't exist or is an empty file. 858 */ 859 void load_file(std::vector<unsigned char>& buffer, const std::string& filename); 860 861 /* 862 Save the binary data in an std::vector to a file on disk. The file is overwritten 863 without warning. 864 */ 865 void save_file(const std::vector<unsigned char>& buffer, const std::string& filename); 866 #endif //LODEPNG_COMPILE_DISK 867 #endif //LODEPNG_COMPILE_PNG 868 869 #ifdef LODEPNG_COMPILE_ZLIB 870 #ifdef LODEPNG_COMPILE_DECODER 871 //Zlib-decompress an unsigned char buffer 872 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 873 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 874 875 //Zlib-decompress an std::vector 876 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 877 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); 878 #endif //LODEPNG_COMPILE_DECODER 879 880 #ifdef LODEPNG_COMPILE_ENCODER 881 //Zlib-compress an unsigned char buffer 882 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, 883 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 884 885 //Zlib-compress an std::vector 886 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, 887 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); 888 #endif //LODEPNG_COMPILE_ENCODER 889 #endif //LODEPNG_COMPILE_ZLIB 890 } //namespace lodepng 891 #endif /*LODEPNG_COMPILE_CPP*/ 892 893 /* 894 TODO: 895 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often 896 [.] check compatibility with vareous compilers - done but needs to be redone for every newer version 897 [X] converting color to 16-bit per channel types 898 [ ] read all public PNG chunk types (but never let the color profile and gamma ones touch RGB values) 899 [ ] make sure encoder generates no chunks with size > (2^31)-1 900 [ ] partial decoding (stream processing) 901 [X] let the "isFullyOpaque" function check color keys and transparent palettes too 902 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl" 903 [ ] don't stop decoding on errors like 69, 57, 58 (make warnings) 904 [ ] make option to choose if the raw image with non multiple of 8 bits per scanline should have padding bits or not 905 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes 906 */ 907 908 #endif /*LODEPNG_H inclusion guard*/ 909 910 /* 911 LodePNG Documentation 912 --------------------- 913 914 0. table of contents 915 -------------------- 916 917 1. about 918 1.1. supported features 919 1.2. features not supported 920 2. C and C++ version 921 3. security 922 4. decoding 923 5. encoding 924 6. color conversions 925 6.1. PNG color types 926 6.2. color conversions 927 6.3. padding bits 928 6.4. A note about 16-bits per channel and endianness 929 7. error values 930 8. chunks and PNG editing 931 9. compiler support 932 10. examples 933 10.1. decoder C++ example 934 10.2. decoder C example 935 11. changes 936 12. contact information 937 938 939 1. about 940 -------- 941 942 PNG is a file format to store raster images losslessly with good compression, 943 supporting different color types and alpha channel. 944 945 LodePNG is a PNG codec according to the Portable Network Graphics (PNG) 946 Specification (Second Edition) - W3C Recommendation 10 November 2003. 947 948 The specifications used are: 949 950 *) Portable Network Graphics (PNG) Specification (Second Edition): 951 http://www.w3.org/TR/2003/REC-PNG-20031110 952 *) RFC 1950 ZLIB Compressed Data Format version 3.3: 953 http://www.gzip.org/zlib/rfc-zlib.html 954 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3: 955 http://www.gzip.org/zlib/rfc-deflate.html 956 957 The most recent version of LodePNG can currently be found at 958 http://lodev.org/lodepng/ 959 960 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds 961 extra functionality. 962 963 LodePNG exists out of two files: 964 -lodepng.h: the header file for both C and C++ 965 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage 966 967 If you want to start using LodePNG right away without reading this doc, get the 968 examples from the LodePNG website to see how to use it in code, or check the 969 smaller examples in chapter 13 here. 970 971 LodePNG is simple but only supports the basic requirements. To achieve 972 simplicity, the following design choices were made: There are no dependencies 973 on any external library. There are functions to decode and encode a PNG with 974 a single function call, and extended versions of these functions taking a 975 LodePNGState struct allowing to specify or get more information. By default 976 the colors of the raw image are always RGB or RGBA, no matter what color type 977 the PNG file uses. To read and write files, there are simple functions to 978 convert the files to/from buffers in memory. 979 980 This all makes LodePNG suitable for loading textures in games, demos and small 981 programs, ... It's less suitable for full fledged image editors, loading PNGs 982 over network (it requires all the image data to be available before decoding can 983 begin), life-critical systems, ... 984 985 1.1. supported features 986 ----------------------- 987 988 The following features are supported by the decoder: 989 990 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image, 991 or the same color type as the PNG 992 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image 993 *) Adam7 interlace and deinterlace for any color type 994 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk 995 *) support for alpha channels, including RGBA color model, translucent palettes and color keying 996 *) zlib decompression (inflate) 997 *) zlib compression (deflate) 998 *) CRC32 and ADLER32 checksums 999 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks. 1000 *) the following chunks are supported (generated/interpreted) by both encoder and decoder: 1001 IHDR: header information 1002 PLTE: color palette 1003 IDAT: pixel data 1004 IEND: the final chunk 1005 tRNS: transparency for palettized images 1006 tEXt: textual information 1007 zTXt: compressed textual information 1008 iTXt: international textual information 1009 bKGD: suggested background color 1010 pHYs: physical dimensions 1011 tIME: modification time 1012 1013 1.2. features not supported 1014 --------------------------- 1015 1016 The following features are _not_ supported: 1017 1018 *) some features needed to make a conformant PNG-Editor might be still missing. 1019 *) partial loading/stream processing. All data must be available and is processed in one call. 1020 *) The following public chunks are not supported but treated as unknown chunks by LodePNG 1021 cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT 1022 Some of these are not supported on purpose: LodePNG wants to provide the RGB values 1023 stored in the pixels, not values modified by system dependent gamma or color models. 1024 1025 1026 2. C and C++ version 1027 -------------------- 1028 1029 The C version uses buffers allocated with alloc that you need to free() 1030 yourself. You need to use init and cleanup functions for each struct whenever 1031 using a struct from the C version to avoid exploits and memory leaks. 1032 1033 The C++ version has extra functions with std::vectors in the interface and the 1034 lodepng::State class which is a LodePNGState with constructor and destructor. 1035 1036 These files work without modification for both C and C++ compilers because all 1037 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers 1038 ignore it, and the C code is made to compile both with strict ISO C90 and C++. 1039 1040 To use the C++ version, you need to rename the source file to lodepng.cpp 1041 (instead of lodepng.c), and compile it with a C++ compiler. 1042 1043 To use the C version, you need to rename the source file to lodepng.c (instead 1044 of lodepng.cpp), and compile it with a C compiler. 1045 1046 1047 3. Security 1048 ----------- 1049 1050 Even if carefully designed, it's always possible that LodePNG contains possible 1051 exploits. If you discover one, please let me know, and it will be fixed. 1052 1053 When using LodePNG, care has to be taken with the C version of LodePNG, as well 1054 as the C-style structs when working with C++. The following conventions are used 1055 for all C-style structs: 1056 1057 -if a struct has a corresponding init function, always call the init function when making a new one 1058 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks 1059 -if a struct has a corresponding copy function, use the copy function instead of "=". 1060 The destination must also be inited already. 1061 1062 1063 4. Decoding 1064 ----------- 1065 1066 Decoding converts a PNG compressed image to a raw pixel buffer. 1067 1068 Most documentation on using the decoder is at its declarations in the header 1069 above. For C, simple decoding can be done with functions such as 1070 lodepng_decode32, and more advanced decoding can be done with the struct 1071 LodePNGState and lodepng_decode. For C++, all decoding can be done with the 1072 various lodepng::decode functions, and lodepng::State can be used for advanced 1073 features. 1074 1075 When using the LodePNGState, it uses the following fields for decoding: 1076 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here 1077 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get 1078 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use 1079 1080 LodePNGInfo info_png 1081 -------------------- 1082 1083 After decoding, this contains extra information of the PNG image, except the actual 1084 pixels, width and height because these are already gotten directly from the decoder 1085 functions. 1086 1087 It contains for example the original color type of the PNG image, text comments, 1088 suggested background color, etc... More details about the LodePNGInfo struct are 1089 at its declaration documentation. 1090 1091 LodePNGColorMode info_raw 1092 ------------------------- 1093 1094 When decoding, here you can specify which color type you want 1095 the resulting raw image to be. If this is different from the colortype of the 1096 PNG, then the decoder will automatically convert the result. This conversion 1097 always works, except if you want it to convert a color PNG to greyscale or to 1098 a palette with missing colors. 1099 1100 By default, 32-bit color is used for the result. 1101 1102 LodePNGDecoderSettings decoder 1103 ------------------------------ 1104 1105 The settings can be used to ignore the errors created by invalid CRC and Adler32 1106 chunks, and to disable the decoding of tEXt chunks. 1107 1108 There's also a setting color_convert, true by default. If false, no conversion 1109 is done, the resulting data will be as it was in the PNG (after decompression) 1110 and you'll have to puzzle the colors of the pixels together yourself using the 1111 color type information in the LodePNGInfo. 1112 1113 1114 5. Encoding 1115 ----------- 1116 1117 Encoding converts a raw pixel buffer to a PNG compressed image. 1118 1119 Most documentation on using the encoder is at its declarations in the header 1120 above. For C, simple encoding can be done with functions such as 1121 lodepng_encode32, and more advanced decoding can be done with the struct 1122 LodePNGState and lodepng_encode. For C++, all encoding can be done with the 1123 various lodepng::encode functions, and lodepng::State can be used for advanced 1124 features. 1125 1126 Like the decoder, the encoder can also give errors. However it gives less errors 1127 since the encoder input is trusted, the decoder input (a PNG image that could 1128 be forged by anyone) is not trusted. 1129 1130 When using the LodePNGState, it uses the following fields for encoding: 1131 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be. 1132 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has 1133 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use 1134 1135 LodePNGInfo info_png 1136 -------------------- 1137 1138 When encoding, you use this the opposite way as when decoding: for encoding, 1139 you fill in the values you want the PNG to have before encoding. By default it's 1140 not needed to specify a color type for the PNG since it's automatically chosen, 1141 but it's possible to choose it yourself given the right settings. 1142 1143 The encoder will not always exactly match the LodePNGInfo struct you give, 1144 it tries as close as possible. Some things are ignored by the encoder. The 1145 encoder uses, for example, the following settings from it when applicable: 1146 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the 1147 background color, the interlace method, unknown chunks, ... 1148 1149 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk. 1150 If the palette contains any colors for which the alpha channel is not 255 (so 1151 there are translucent colors in the palette), it'll add a tRNS chunk. 1152 1153 LodePNGColorMode info_raw 1154 ------------------------- 1155 1156 You specify the color type of the raw image that you give to the input here, 1157 including a possible transparent color key and palette you happen to be using in 1158 your raw image data. 1159 1160 By default, 32-bit color is assumed, meaning your input has to be in RGBA 1161 format with 4 bytes (unsigned chars) per pixel. 1162 1163 LodePNGEncoderSettings encoder 1164 ------------------------------ 1165 1166 The following settings are supported (some are in sub-structs): 1167 *) auto_convert: when this option is enabled, the encoder will 1168 automatically choose the smallest possible color mode (including color key) that 1169 can encode the colors of all pixels without information loss. 1170 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree, 1171 2 = dynamic huffman tree (best compression). Should be 2 for proper 1172 compression. 1173 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be 1174 true for proper compression. 1175 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value 1176 2048 by default, but can be set to 32768 for better, but slow, compression. 1177 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE 1178 chunk if force_palette is true. This can used as suggested palette to convert 1179 to by viewers that don't support more than 256 colors (if those still exist) 1180 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image. 1181 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks. 1182 zTXt chunks use zlib compression on the text. This gives a smaller result on 1183 large texts but a larger result on small texts (such as a single program name). 1184 It's all tEXt or all zTXt though, there's no separate setting per text yet. 1185 1186 1187 6. color conversions 1188 -------------------- 1189 1190 An important thing to note about LodePNG, is that the color type of the PNG, and 1191 the color type of the raw image, are completely independent. By default, when 1192 you decode a PNG, you get the result as a raw image in the color type you want, 1193 no matter whether the PNG was encoded with a palette, greyscale or RGBA color. 1194 And if you encode an image, by default LodePNG will automatically choose the PNG 1195 color type that gives good compression based on the values of colors and amount 1196 of colors in the image. It can be configured to let you control it instead as 1197 well, though. 1198 1199 To be able to do this, LodePNG does conversions from one color mode to another. 1200 It can convert from almost any color type to any other color type, except the 1201 following conversions: RGB to greyscale is not supported, and converting to a 1202 palette when the palette doesn't have a required color is not supported. This is 1203 not supported on purpose: this is information loss which requires a color 1204 reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to grey 1205 is easy, but there are multiple ways if you want to give some channels more 1206 weight). 1207 1208 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB 1209 color, no matter what color type the PNG has. And by default when encoding, 1210 LodePNG automatically picks the best color model for the output PNG, and expects 1211 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control 1212 the color format of the images yourself, you can skip this chapter. 1213 1214 6.1. PNG color types 1215 -------------------- 1216 1217 A PNG image can have many color types, ranging from 1-bit color to 64-bit color, 1218 as well as palettized color modes. After the zlib decompression and unfiltering 1219 in the PNG image is done, the raw pixel data will have that color type and thus 1220 a certain amount of bits per pixel. If you want the output raw image after 1221 decoding to have another color type, a conversion is done by LodePNG. 1222 1223 The PNG specification gives the following color types: 1224 1225 0: greyscale, bit depths 1, 2, 4, 8, 16 1226 2: RGB, bit depths 8 and 16 1227 3: palette, bit depths 1, 2, 4 and 8 1228 4: greyscale with alpha, bit depths 8 and 16 1229 6: RGBA, bit depths 8 and 16 1230 1231 Bit depth is the amount of bits per pixel per color channel. So the total amount 1232 of bits per pixel is: amount of channels * bitdepth. 1233 1234 6.2. color conversions 1235 ---------------------- 1236 1237 As explained in the sections about the encoder and decoder, you can specify 1238 color types and bit depths in info_png and info_raw to change the default 1239 behaviour. 1240 1241 If, when decoding, you want the raw image to be something else than the default, 1242 you need to set the color type and bit depth you want in the LodePNGColorMode, 1243 or the parameters of the simple function of LodePNG you're using. 1244 1245 If, when encoding, you use another color type than the default in the input 1246 image, you need to specify its color type and bit depth in the LodePNGColorMode 1247 of the raw image, or use the parameters of the simplefunction of LodePNG you're 1248 using. 1249 1250 If, when encoding, you don't want LodePNG to choose the output PNG color type 1251 but control it yourself, you need to set auto_convert in the encoder settings 1252 to LAC_NONE, and specify the color type you want in the LodePNGInfo of the 1253 encoder. 1254 1255 If you do any of the above, LodePNG may need to do a color conversion, which 1256 follows the rules below, and may sometimes not be allowed. 1257 1258 To avoid some confusion: 1259 -the decoder converts from PNG to raw image 1260 -the encoder converts from raw image to PNG 1261 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image 1262 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG 1263 -when encoding, the color type in LodePNGInfo is ignored if auto_convert 1264 is enabled, it is automatically generated instead 1265 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original 1266 PNG image, but it can be ignored since the raw image has the color type you requested instead 1267 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion 1268 between the color types is done if the color types are supported. If it is not 1269 supported, an error is returned. If the types are the same, no conversion is done. 1270 -even though some conversions aren't supported, LodePNG supports loading PNGs from any 1271 colortype and saving PNGs to any colortype, sometimes it just requires preparing 1272 the raw image correctly before encoding. 1273 -both encoder and decoder use the same color converter. 1274 1275 Non supported color conversions: 1276 -color to greyscale: no error is thrown, but the result will look ugly because 1277 only the red channel is taken 1278 -anything, to palette when that palette does not have that color in it: in this 1279 case an error is thrown 1280 1281 Supported color conversions: 1282 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA 1283 -any grey or grey+alpha, to grey or grey+alpha 1284 -anything to a palette, as long as the palette has the requested colors in it 1285 -removing alpha channel 1286 -higher to smaller bitdepth, and vice versa 1287 1288 If you want no color conversion to be done: 1289 -In the encoder, you can make it save a PNG with any color type by giving the 1290 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to 1291 LAC_NO. 1292 -In the decoder, you can make it store the pixel data in the same color type 1293 as the PNG has, by setting the color_convert setting to false. Settings in 1294 info_raw are then ignored. 1295 1296 The function lodepng_convert does the color conversion. It is available in the 1297 interface but normally isn't needed since the encoder and decoder already call 1298 it. 1299 1300 6.3. padding bits 1301 ----------------- 1302 1303 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines 1304 have a bit amount that isn't a multiple of 8, then padding bits are used so that each 1305 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output. 1306 The raw input image you give to the encoder, and the raw output image you get from the decoder 1307 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width 1308 of 7 pixels, the first pixel of the second scanline will the the 8th bit of the first byte, 1309 not the first bit of a new byte. 1310 1311 6.4. A note about 16-bits per channel and endianness 1312 ---------------------------------------------------- 1313 1314 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like 1315 for any other color format. The 16-bit values are stored in big endian (most 1316 significant byte first) in these arrays. This is the opposite order of the 1317 little endian used by x86 CPU's. 1318 1319 LodePNG always uses big endian because the PNG file format does so internally. 1320 Conversions to other formats than PNG uses internally are not supported by 1321 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit 1322 colors, the order in which you store R, G, B and A, and so on. Supporting and 1323 converting to/from all that is outside the scope of LodePNG. 1324 1325 This may mean that, depending on your use case, you may want to convert the big 1326 endian output of LodePNG to little endian with a for loop. This is certainly not 1327 always needed, many applications and libraries support big endian 16-bit colors 1328 anyway, but it means you cannot simply cast the unsigned char* buffer to an 1329 unsigned short* buffer on x86 CPUs. 1330 1331 1332 7. error values 1333 --------------- 1334 1335 All functions in LodePNG that return an error code, return 0 if everything went 1336 OK, or a non-zero code if there was an error. 1337 1338 The meaning of the LodePNG error values can be retrieved with the function 1339 lodepng_error_text: given the numerical error code, it returns a description 1340 of the error in English as a string. 1341 1342 Check the implementation of lodepng_error_text to see the meaning of each code. 1343 1344 1345 8. chunks and PNG editing 1346 ------------------------- 1347 1348 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG 1349 editor that should follow the rules about handling of unknown chunks, or if your 1350 program is able to read other types of chunks than the ones handled by LodePNG, 1351 then that's possible with the chunk functions of LodePNG. 1352 1353 A PNG chunk has the following layout: 1354 1355 4 bytes length 1356 4 bytes type name 1357 length bytes data 1358 4 bytes CRC 1359 1360 8.1. iterating through chunks 1361 ----------------------------- 1362 1363 If you have a buffer containing the PNG image data, then the first chunk (the 1364 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the 1365 signature of the PNG and are not part of a chunk. But if you start at byte 8 1366 then you have a chunk, and can check the following things of it. 1367 1368 NOTE: none of these functions check for memory buffer boundaries. To avoid 1369 exploits, always make sure the buffer contains all the data of the chunks. 1370 When using lodepng_chunk_next, make sure the returned value is within the 1371 allocated memory. 1372 1373 unsigned lodepng_chunk_length(const unsigned char* chunk): 1374 1375 Get the length of the chunk's data. The total chunk length is this length + 12. 1376 1377 void lodepng_chunk_type(char type[5], const unsigned char* chunk): 1378 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type): 1379 1380 Get the type of the chunk or compare if it's a certain type 1381 1382 unsigned char lodepng_chunk_critical(const unsigned char* chunk): 1383 unsigned char lodepng_chunk_private(const unsigned char* chunk): 1384 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk): 1385 1386 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are). 1387 Check if the chunk is private (public chunks are part of the standard, private ones not). 1388 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical 1389 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your 1390 program doesn't handle that type of unknown chunk. 1391 1392 unsigned char* lodepng_chunk_data(unsigned char* chunk): 1393 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk): 1394 1395 Get a pointer to the start of the data of the chunk. 1396 1397 unsigned lodepng_chunk_check_crc(const unsigned char* chunk): 1398 void lodepng_chunk_generate_crc(unsigned char* chunk): 1399 1400 Check if the crc is correct or generate a correct one. 1401 1402 unsigned char* lodepng_chunk_next(unsigned char* chunk): 1403 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk): 1404 1405 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these 1406 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough 1407 data available in the buffer to be able to go to the next chunk. 1408 1409 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk): 1410 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, 1411 const char* type, const unsigned char* data): 1412 1413 These functions are used to create new chunks that are appended to the data in *out that has 1414 length *outlength. The append function appends an existing chunk to the new data. The create 1415 function creates a new chunk with the given parameters and appends it. Type is the 4-letter 1416 name of the chunk. 1417 1418 8.2. chunks in info_png 1419 ----------------------- 1420 1421 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3 1422 buffers (each with size) to contain 3 types of unknown chunks: 1423 the ones that come before the PLTE chunk, the ones that come between the PLTE 1424 and the IDAT chunks, and the ones that come after the IDAT chunks. 1425 It's necessary to make the distionction between these 3 cases because the PNG 1426 standard forces to keep the ordering of unknown chunks compared to the critical 1427 chunks, but does not force any other ordering rules. 1428 1429 info_png.unknown_chunks_data[0] is the chunks before PLTE 1430 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT 1431 info_png.unknown_chunks_data[2] is the chunks after IDAT 1432 1433 The chunks in these 3 buffers can be iterated through and read by using the same 1434 way described in the previous subchapter. 1435 1436 When using the decoder to decode a PNG, you can make it store all unknown chunks 1437 if you set the option settings.remember_unknown_chunks to 1. By default, this 1438 option is off (0). 1439 1440 The encoder will always encode unknown chunks that are stored in the info_png. 1441 If you need it to add a particular chunk that isn't known by LodePNG, you can 1442 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in 1443 info_png.unknown_chunks_data[x]. 1444 1445 Chunks that are known by LodePNG should not be added in that way. E.g. to make 1446 LodePNG add a bKGD chunk, set background_defined to true and add the correct 1447 parameters there instead. 1448 1449 1450 9. compiler support 1451 ------------------- 1452 1453 No libraries other than the current standard C library are needed to compile 1454 LodePNG. For the C++ version, only the standard C++ library is needed on top. 1455 Add the files lodepng.c(pp) and lodepng.h to your project, include 1456 lodepng.h where needed, and your program can read/write PNG files. 1457 1458 If performance is important, use optimization when compiling! For both the 1459 encoder and decoder, this makes a large difference. 1460 1461 Make sure that LodePNG is compiled with the same compiler of the same version 1462 and with the same settings as the rest of the program, or the interfaces with 1463 std::vectors and std::strings in C++ can be incompatible. 1464 1465 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets. 1466 1467 *) gcc and g++ 1468 1469 LodePNG is developed in gcc so this compiler is natively supported. It gives no 1470 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++ 1471 version 4.7.1 on Linux, 32-bit and 64-bit. 1472 1473 *) Mingw 1474 1475 The Mingw compiler (a port of gcc) for Windows is fully supported by LodePNG. 1476 1477 *) Visual Studio 2005 and up, Visual C++ Express Edition 2005 and up 1478 1479 Visual Studio may give warnings about 'fopen' being deprecated. A multiplatform library 1480 can't support the proposed Visual Studio alternative however, so LodePNG keeps using 1481 fopen. If you don't want to see the deprecated warnings, put this on top of lodepng.h 1482 before the inclusions: 1483 #define _CRT_SECURE_NO_DEPRECATE 1484 1485 Other than the above warnings, LodePNG should be warning-free with warning 1486 level 3 (W3). Warning level 4 (W4) will give warnings about integer conversions. 1487 I'm not planning to resolve these warnings. To get rid of them, let Visual 1488 Studio use warning level W3 for lodepng.cpp only: right click lodepng.cpp, 1489 Properties, C/C++, General, Warning Level: Level 3 (/W3). 1490 1491 Visual Studio may want "stdafx.h" files to be included in each source file and 1492 give an error "unexpected end of file while looking for precompiled header". 1493 That is not standard C++ and will not be added to the stock LodePNG. You can 1494 disable it for lodepng.cpp only by right clicking it, Properties, C/C++, 1495 Precompiled Headers, and set it to Not Using Precompiled Headers there. 1496 1497 *) Visual Studio 6.0 1498 1499 LodePNG support for Visual Studio 6.0 is not guaranteed because VS6 doesn't 1500 follow the C++ standard correctly. 1501 1502 *) Comeau C/C++ 1503 1504 Vesion 20070107 compiles without problems on the Comeau C/C++ Online Test Drive 1505 at http://www.comeaucomputing.com/tryitout in both C90 and C++ mode. 1506 1507 *) Compilers on Macintosh 1508 1509 LodePNG has been reported to work both with the gcc and LLVM for Macintosh, both 1510 for C and C++. 1511 1512 *) Other Compilers 1513 1514 If you encounter problems on other compilers, feel free to let me know and I may 1515 try to fix it if the compiler is modern standards complient. 1516 1517 1518 10. examples 1519 ------------ 1520 1521 This decoder example shows the most basic usage of LodePNG. More complex 1522 examples can be found on the LodePNG website. 1523 1524 10.1. decoder C++ example 1525 ------------------------- 1526 1527 #include "lodepng.h" 1528 #include <iostream> 1529 1530 int main(int argc, char *argv[]) 1531 { 1532 const char* filename = argc > 1 ? argv[1] : "test.png"; 1533 1534 //load and decode 1535 std::vector<unsigned char> image; 1536 unsigned width, height; 1537 unsigned error = lodepng::decode(image, width, height, filename); 1538 1539 //if there's an error, display it 1540 if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl; 1541 1542 //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ... 1543 } 1544 1545 10.2. decoder C example 1546 ----------------------- 1547 1548 #include "lodepng.h" 1549 1550 int main(int argc, char *argv[]) 1551 { 1552 unsigned error; 1553 unsigned char* image; 1554 size_t width, height; 1555 const char* filename = argc > 1 ? argv[1] : "test.png"; 1556 1557 error = lodepng_decode32_file(&image, &width, &height, filename); 1558 1559 if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error)); 1560 1561 / * use image here * / 1562 1563 free(image); 1564 return 0; 1565 } 1566 1567 1568 11. changes 1569 ----------- 1570 1571 The version number of LodePNG is the date of the change given in the format 1572 yyyymmdd. 1573 1574 Some changes aren't backwards compatible. Those are indicated with a (!) 1575 symbol. 1576 1577 *) 22 dec 2013: Power of two windowsize required for optimization. 1578 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key. 1579 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png). 1580 *) 11 mar 2013 (!): Bugfix with custom free. Changed from "my" to "lodepng_" 1581 prefix for the custom allocators and made it possible with a new #define to 1582 use custom ones in your project without needing to change lodepng's code. 1583 *) 28 jan 2013: Bugfix with color key. 1584 *) 27 okt 2012: Tweaks in text chunk keyword length error handling. 1585 *) 8 okt 2012 (!): Added new filter strategy (entropy) and new auto color mode. 1586 (no palette). Better deflate tree encoding. New compression tweak settings. 1587 Faster color conversions while decoding. Some internal cleanups. 1588 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit. 1589 *) 1 sep 2012 (!): Removed #define's for giving custom (de)compression functions 1590 and made it work with function pointers instead. 1591 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc 1592 and free functions and toggle #defines from compiler flags. Small fixes. 1593 *) 6 may 2012 (!): Made plugging in custom zlib/deflate functions more flexible. 1594 *) 22 apr 2012 (!): Made interface more consistent, renaming a lot. Removed 1595 redundant C++ codec classes. Reduced amount of structs. Everything changed, 1596 but it is cleaner now imho and functionality remains the same. Also fixed 1597 several bugs and shrinked the implementation code. Made new samples. 1598 *) 6 nov 2011 (!): By default, the encoder now automatically chooses the best 1599 PNG color model and bit depth, based on the amount and type of colors of the 1600 raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color. 1601 *) 9 okt 2011: simpler hash chain implementation for the encoder. 1602 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching. 1603 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking. 1604 A bug with the PNG filtertype heuristic was fixed, so that it chooses much 1605 better ones (it's quite significant). A setting to do an experimental, slow, 1606 brute force search for PNG filter types is added. 1607 *) 17 aug 2011 (!): changed some C zlib related function names. 1608 *) 16 aug 2011: made the code less wide (max 120 characters per line). 1609 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors. 1610 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled. 1611 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman 1612 to optimize long sequences of zeros. 1613 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and 1614 LodePNG_InfoColor_canHaveAlpha functions for convenience. 1615 *) 7 nov 2010: added LodePNG_error_text function to get error code description. 1616 *) 30 okt 2010: made decoding slightly faster 1617 *) 26 okt 2010: (!) changed some C function and struct names (more consistent). 1618 Reorganized the documentation and the declaration order in the header. 1619 *) 08 aug 2010: only changed some comments and external samples. 1620 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version. 1621 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers. 1622 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could 1623 read by ignoring the problem but windows apps couldn't. 1624 *) 06 jun 2008: added more error checks for out of memory cases. 1625 *) 26 apr 2008: added a few more checks here and there to ensure more safety. 1626 *) 06 mar 2008: crash with encoding of strings fixed 1627 *) 02 feb 2008: support for international text chunks added (iTXt) 1628 *) 23 jan 2008: small cleanups, and #defines to divide code in sections 1629 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor. 1630 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder. 1631 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added 1632 Also vareous fixes, such as in the deflate and the padding bits code. 1633 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved 1634 filtering code of encoder. 1635 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A 1636 C++ wrapper around this provides an interface almost identical to before. 1637 Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code 1638 are together in these files but it works both for C and C++ compilers. 1639 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks 1640 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible 1641 *) 09 aug 2007: some VS2005 warnings removed again 1642 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code 1643 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images 1644 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing 1645 invalid std::vector element [0] fixed, and level 3 and 4 warnings removed 1646 *) 02 jun 2007: made the encoder add a tag with version by default 1647 *) 27 may 2007: zlib and png code separated (but still in the same file), 1648 simple encoder/decoder functions added for more simple usage cases 1649 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69), 1650 moved some examples from here to lodepng_examples.cpp 1651 *) 12 may 2007: palette decoding bug fixed 1652 *) 24 apr 2007: changed the license from BSD to the zlib license 1653 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks. 1654 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding 1655 palettized PNG images. Plus little interface change with palette and texts. 1656 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes. 1657 Fixed a bug where the end code of a block had length 0 in the Huffman tree. 1658 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented 1659 and supported by the encoder, resulting in smaller PNGs at the output. 1660 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone. 1661 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any 1662 greyscale type to 8-bit greyscale with or without alpha. 1663 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types 1664 to convert to and is more uniform. See the manual for how it works now. 1665 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days: 1666 encode/decode custom tEXt chunks, separate classes for zlib & deflate, and 1667 at last made the decoder give errors for incorrect Adler32 or Crc. 1668 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel. 1669 *) 29 dec 2006: Added support for encoding images without alpha channel, and 1670 cleaned out code as well as making certain parts faster. 1671 *) 28 dec 2006: Added "Settings" to the encoder. 1672 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now. 1673 Removed some code duplication in the decoder. Fixed little bug in an example. 1674 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter. 1675 Fixed a bug of the decoder with 16-bit per color. 1676 *) 15 okt 2006: Changed documentation structure 1677 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the 1678 given image buffer, however for now it's not compressed. 1679 *) 08 sep 2006: (!) Changed to interface with a Decoder class 1680 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different 1681 way. Renamed decodePNG to decodePNGGeneric. 1682 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a 1683 struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy. 1684 *) 28 jul 2006: Cleaned the code and added new error checks. 1685 Corrected terminology "deflate" into "inflate". 1686 *) 23 jun 2006: Added SDL example in the documentation in the header, this 1687 example allows easy debugging by displaying the PNG and its transparency. 1688 *) 22 jun 2006: (!) Changed way to obtain error value. Added 1689 loadFile function for convenience. Made decodePNG32 faster. 1690 *) 21 jun 2006: (!) Changed type of info vector to unsigned. 1691 Changed position of palette in info vector. Fixed an important bug that 1692 happened on PNGs with an uncompressed block. 1693 *) 16 jun 2006: Internally changed unsigned into unsigned where 1694 needed, and performed some optimizations. 1695 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them 1696 in LodePNG namespace. Changed the order of the parameters. Rewrote the 1697 documentation in the header. Renamed files to lodepng.cpp and lodepng.h 1698 *) 22 apr 2006: Optimized and improved some code 1699 *) 07 sep 2005: (!) Changed to std::vector interface 1700 *) 12 aug 2005: Initial release (C++, decoder only) 1701 1702 1703 12. contact information 1704 ----------------------- 1705 1706 Feel free to contact me with suggestions, problems, comments, ... concerning 1707 LodePNG. If you encounter a PNG image that doesn't work properly with this 1708 decoder, feel free to send it and I'll use it to find and fix the problem. 1709 1710 My email address is (puzzle the account and domain together with an @ symbol): 1711 Domain: gmail dot com. 1712 Account: lode dot vandevenne. 1713 1714 1715 Copyright (c) 2005-2013 Lode Vandevenne 1716 */ 1717
