Mercurial > games > semicongine
comparison semiconginev2/contrib/lodepng.h @ 1242:e8b3dc80e48e
add: PNG loading and tests for it
author | sam <sam@basx.dev> |
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date | Mon, 22 Jul 2024 15:53:32 +0700 |
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1241:a0ed1a918fda | 1242:e8b3dc80e48e |
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1 /* | |
2 LodePNG version 20230410 | |
3 | |
4 Copyright (c) 2005-2023 Lode Vandevenne | |
5 | |
6 This software is provided 'as-is', without any express or implied | |
7 warranty. In no event will the authors be held liable for any damages | |
8 arising from the use of this software. | |
9 | |
10 Permission is granted to anyone to use this software for any purpose, | |
11 including commercial applications, and to alter it and redistribute it | |
12 freely, subject to the following restrictions: | |
13 | |
14 1. The origin of this software must not be misrepresented; you must not | |
15 claim that you wrote the original software. If you use this software | |
16 in a product, an acknowledgment in the product documentation would be | |
17 appreciated but is not required. | |
18 | |
19 2. Altered source versions must be plainly marked as such, and must not be | |
20 misrepresented as being the original software. | |
21 | |
22 3. This notice may not be removed or altered from any source | |
23 distribution. | |
24 */ | |
25 | |
26 #ifndef LODEPNG_H | |
27 #define LODEPNG_H | |
28 | |
29 #include <string.h> /*for size_t*/ | |
30 | |
31 extern const char* LODEPNG_VERSION_STRING; | |
32 | |
33 /* | |
34 The following #defines are used to create code sections. They can be disabled | |
35 to disable code sections, which can give faster compile time and smaller binary. | |
36 The "NO_COMPILE" defines are designed to be used to pass as defines to the | |
37 compiler command to disable them without modifying this header, e.g. | |
38 -DLODEPNG_NO_COMPILE_ZLIB for gcc or clang. | |
39 */ | |
40 /*deflate & zlib. If disabled, you must specify alternative zlib functions in | |
41 the custom_zlib field of the compress and decompress settings*/ | |
42 #ifndef LODEPNG_NO_COMPILE_ZLIB | |
43 /*pass -DLODEPNG_NO_COMPILE_ZLIB to the compiler to disable this, or comment out LODEPNG_COMPILE_ZLIB below*/ | |
44 #define LODEPNG_COMPILE_ZLIB | |
45 #endif | |
46 | |
47 /*png encoder and png decoder*/ | |
48 #ifndef LODEPNG_NO_COMPILE_PNG | |
49 /*pass -DLODEPNG_NO_COMPILE_PNG to the compiler to disable this, or comment out LODEPNG_COMPILE_PNG below*/ | |
50 #define LODEPNG_COMPILE_PNG | |
51 #endif | |
52 | |
53 /*deflate&zlib decoder and png decoder*/ | |
54 #ifndef LODEPNG_NO_COMPILE_DECODER | |
55 /*pass -DLODEPNG_NO_COMPILE_DECODER to the compiler to disable this, or comment out LODEPNG_COMPILE_DECODER below*/ | |
56 #define LODEPNG_COMPILE_DECODER | |
57 #endif | |
58 | |
59 /*deflate&zlib encoder and png encoder*/ | |
60 #ifndef LODEPNG_NO_COMPILE_ENCODER | |
61 /*pass -DLODEPNG_NO_COMPILE_ENCODER to the compiler to disable this, or comment out LODEPNG_COMPILE_ENCODER below*/ | |
62 #define LODEPNG_COMPILE_ENCODER | |
63 #endif | |
64 | |
65 /*the optional built in harddisk file loading and saving functions*/ | |
66 #ifndef LODEPNG_NO_COMPILE_DISK | |
67 /*pass -DLODEPNG_NO_COMPILE_DISK to the compiler to disable this, or comment out LODEPNG_COMPILE_DISK below*/ | |
68 #define LODEPNG_COMPILE_DISK | |
69 #endif | |
70 | |
71 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/ | |
72 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS | |
73 /*pass -DLODEPNG_NO_COMPILE_ANCILLARY_CHUNKS to the compiler to disable this, | |
74 or comment out LODEPNG_COMPILE_ANCILLARY_CHUNKS below*/ | |
75 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
76 #endif | |
77 | |
78 /*ability to convert error numerical codes to English text string*/ | |
79 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT | |
80 /*pass -DLODEPNG_NO_COMPILE_ERROR_TEXT to the compiler to disable this, | |
81 or comment out LODEPNG_COMPILE_ERROR_TEXT below*/ | |
82 #define LODEPNG_COMPILE_ERROR_TEXT | |
83 #endif | |
84 | |
85 /*Compile the default allocators (C's free, malloc and realloc). If you disable this, | |
86 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your | |
87 source files with custom allocators.*/ | |
88 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS | |
89 /*pass -DLODEPNG_NO_COMPILE_ALLOCATORS to the compiler to disable the built-in ones, | |
90 or comment out LODEPNG_COMPILE_ALLOCATORS below*/ | |
91 #define LODEPNG_COMPILE_ALLOCATORS | |
92 #endif | |
93 | |
94 /*Disable built-in CRC function, in that case a custom implementation of | |
95 lodepng_crc32 must be defined externally so that it can be linked in. | |
96 The default built-in CRC code comes with 8KB of lookup tables, so for memory constrained environment you may want it | |
97 disabled and provide a much smaller implementation externally as said above. You can find such an example implementation | |
98 in a comment in the lodepng.c(pp) file in the 'else' case of the searchable LODEPNG_COMPILE_CRC section.*/ | |
99 #ifndef LODEPNG_NO_COMPILE_CRC | |
100 /*pass -DLODEPNG_NO_COMPILE_CRC to the compiler to disable the built-in one, | |
101 or comment out LODEPNG_COMPILE_CRC below*/ | |
102 #define LODEPNG_COMPILE_CRC | |
103 #endif | |
104 | |
105 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/ | |
106 #ifdef __cplusplus | |
107 #ifndef LODEPNG_NO_COMPILE_CPP | |
108 /*pass -DLODEPNG_NO_COMPILE_CPP to the compiler to disable C++ (not needed if a C-only compiler), | |
109 or comment out LODEPNG_COMPILE_CPP below*/ | |
110 #define LODEPNG_COMPILE_CPP | |
111 #endif | |
112 #endif | |
113 | |
114 #ifdef LODEPNG_COMPILE_CPP | |
115 #include <vector> | |
116 #include <string> | |
117 #endif /*LODEPNG_COMPILE_CPP*/ | |
118 | |
119 #ifdef LODEPNG_COMPILE_PNG | |
120 /*The PNG color types (also used for raw image).*/ | |
121 typedef enum LodePNGColorType { | |
122 LCT_GREY = 0, /*grayscale: 1,2,4,8,16 bit*/ | |
123 LCT_RGB = 2, /*RGB: 8,16 bit*/ | |
124 LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/ | |
125 LCT_GREY_ALPHA = 4, /*grayscale with alpha: 8,16 bit*/ | |
126 LCT_RGBA = 6, /*RGB with alpha: 8,16 bit*/ | |
127 /*LCT_MAX_OCTET_VALUE lets the compiler allow this enum to represent any invalid | |
128 byte value from 0 to 255 that could be present in an invalid PNG file header. Do | |
129 not use, compare with or set the name LCT_MAX_OCTET_VALUE, instead either use | |
130 the valid color type names above, or numeric values like 1 or 7 when checking for | |
131 particular disallowed color type byte values, or cast to integer to print it.*/ | |
132 LCT_MAX_OCTET_VALUE = 255 | |
133 } LodePNGColorType; | |
134 | |
135 #ifdef LODEPNG_COMPILE_DECODER | |
136 /* | |
137 Converts PNG data in memory to raw pixel data. | |
138 out: Output parameter. Pointer to buffer that will contain the raw pixel data. | |
139 After decoding, its size is w * h * (bytes per pixel) bytes larger than | |
140 initially. Bytes per pixel depends on colortype and bitdepth. | |
141 Must be freed after usage with free(*out). | |
142 Note: for 16-bit per channel colors, uses big endian format like PNG does. | |
143 w: Output parameter. Pointer to width of pixel data. | |
144 h: Output parameter. Pointer to height of pixel data. | |
145 in: Memory buffer with the PNG file. | |
146 insize: size of the in buffer. | |
147 colortype: the desired color type for the raw output image. See explanation on PNG color types. | |
148 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types. | |
149 Return value: LodePNG error code (0 means no error). | |
150 */ | |
151 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, | |
152 const unsigned char* in, size_t insize, | |
153 LodePNGColorType colortype, unsigned bitdepth); | |
154 | |
155 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/ | |
156 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, | |
157 const unsigned char* in, size_t insize); | |
158 | |
159 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/ | |
160 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, | |
161 const unsigned char* in, size_t insize); | |
162 | |
163 #ifdef LODEPNG_COMPILE_DISK | |
164 /* | |
165 Load PNG from disk, from file with given name. | |
166 Same as the other decode functions, but instead takes a filename as input. | |
167 | |
168 NOTE: Wide-character filenames are not supported, you can use an external method | |
169 to handle such files and decode in-memory.*/ | |
170 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, | |
171 const char* filename, | |
172 LodePNGColorType colortype, unsigned bitdepth); | |
173 | |
174 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image. | |
175 | |
176 NOTE: Wide-character filenames are not supported, you can use an external method | |
177 to handle such files and decode in-memory.*/ | |
178 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, | |
179 const char* filename); | |
180 | |
181 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image. | |
182 | |
183 NOTE: Wide-character filenames are not supported, you can use an external method | |
184 to handle such files and decode in-memory.*/ | |
185 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, | |
186 const char* filename); | |
187 #endif /*LODEPNG_COMPILE_DISK*/ | |
188 #endif /*LODEPNG_COMPILE_DECODER*/ | |
189 | |
190 | |
191 #ifdef LODEPNG_COMPILE_ENCODER | |
192 /* | |
193 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth | |
194 of the output PNG image cannot be chosen, they are automatically determined | |
195 by the colortype, bitdepth and content of the input pixel data. | |
196 Note: for 16-bit per channel colors, needs big endian format like PNG does. | |
197 out: Output parameter. Pointer to buffer that will contain the PNG image data. | |
198 Must be freed after usage with free(*out). | |
199 outsize: Output parameter. Pointer to the size in bytes of the out buffer. | |
200 image: The raw pixel data to encode. The size of this buffer should be | |
201 w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth. | |
202 w: width of the raw pixel data in pixels. | |
203 h: height of the raw pixel data in pixels. | |
204 colortype: the color type of the raw input image. See explanation on PNG color types. | |
205 bitdepth: the bit depth of the raw input image. See explanation on PNG color types. | |
206 Return value: LodePNG error code (0 means no error). | |
207 */ | |
208 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, | |
209 const unsigned char* image, unsigned w, unsigned h, | |
210 LodePNGColorType colortype, unsigned bitdepth); | |
211 | |
212 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/ | |
213 unsigned lodepng_encode32(unsigned char** out, size_t* outsize, | |
214 const unsigned char* image, unsigned w, unsigned h); | |
215 | |
216 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/ | |
217 unsigned lodepng_encode24(unsigned char** out, size_t* outsize, | |
218 const unsigned char* image, unsigned w, unsigned h); | |
219 | |
220 #ifdef LODEPNG_COMPILE_DISK | |
221 /* | |
222 Converts raw pixel data into a PNG file on disk. | |
223 Same as the other encode functions, but instead takes a filename as output. | |
224 | |
225 NOTE: This overwrites existing files without warning! | |
226 | |
227 NOTE: Wide-character filenames are not supported, you can use an external method | |
228 to handle such files and encode in-memory.*/ | |
229 unsigned lodepng_encode_file(const char* filename, | |
230 const unsigned char* image, unsigned w, unsigned h, | |
231 LodePNGColorType colortype, unsigned bitdepth); | |
232 | |
233 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image. | |
234 | |
235 NOTE: Wide-character filenames are not supported, you can use an external method | |
236 to handle such files and encode in-memory.*/ | |
237 unsigned lodepng_encode32_file(const char* filename, | |
238 const unsigned char* image, unsigned w, unsigned h); | |
239 | |
240 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image. | |
241 | |
242 NOTE: Wide-character filenames are not supported, you can use an external method | |
243 to handle such files and encode in-memory.*/ | |
244 unsigned lodepng_encode24_file(const char* filename, | |
245 const unsigned char* image, unsigned w, unsigned h); | |
246 #endif /*LODEPNG_COMPILE_DISK*/ | |
247 #endif /*LODEPNG_COMPILE_ENCODER*/ | |
248 | |
249 | |
250 #ifdef LODEPNG_COMPILE_CPP | |
251 namespace lodepng { | |
252 #ifdef LODEPNG_COMPILE_DECODER | |
253 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype | |
254 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/ | |
255 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, | |
256 const unsigned char* in, size_t insize, | |
257 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
258 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, | |
259 const std::vector<unsigned char>& in, | |
260 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
261 #ifdef LODEPNG_COMPILE_DISK | |
262 /* | |
263 Converts PNG file from disk to raw pixel data in memory. | |
264 Same as the other decode functions, but instead takes a filename as input. | |
265 | |
266 NOTE: Wide-character filenames are not supported, you can use an external method | |
267 to handle such files and decode in-memory. | |
268 */ | |
269 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, | |
270 const std::string& filename, | |
271 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
272 #endif /* LODEPNG_COMPILE_DISK */ | |
273 #endif /* LODEPNG_COMPILE_DECODER */ | |
274 | |
275 #ifdef LODEPNG_COMPILE_ENCODER | |
276 /*Same as lodepng_encode_memory, but encodes to an std::vector. colortype | |
277 is that of the raw input data. The output PNG color type will be auto chosen.*/ | |
278 unsigned encode(std::vector<unsigned char>& out, | |
279 const unsigned char* in, unsigned w, unsigned h, | |
280 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
281 unsigned encode(std::vector<unsigned char>& out, | |
282 const std::vector<unsigned char>& in, unsigned w, unsigned h, | |
283 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
284 #ifdef LODEPNG_COMPILE_DISK | |
285 /* | |
286 Converts 32-bit RGBA raw pixel data into a PNG file on disk. | |
287 Same as the other encode functions, but instead takes a filename as output. | |
288 | |
289 NOTE: This overwrites existing files without warning! | |
290 | |
291 NOTE: Wide-character filenames are not supported, you can use an external method | |
292 to handle such files and decode in-memory. | |
293 */ | |
294 unsigned encode(const std::string& filename, | |
295 const unsigned char* in, unsigned w, unsigned h, | |
296 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
297 unsigned encode(const std::string& filename, | |
298 const std::vector<unsigned char>& in, unsigned w, unsigned h, | |
299 LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
300 #endif /* LODEPNG_COMPILE_DISK */ | |
301 #endif /* LODEPNG_COMPILE_ENCODER */ | |
302 } /* namespace lodepng */ | |
303 #endif /*LODEPNG_COMPILE_CPP*/ | |
304 #endif /*LODEPNG_COMPILE_PNG*/ | |
305 | |
306 #ifdef LODEPNG_COMPILE_ERROR_TEXT | |
307 /*Returns an English description of the numerical error code.*/ | |
308 const char* lodepng_error_text(unsigned code); | |
309 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/ | |
310 | |
311 #ifdef LODEPNG_COMPILE_DECODER | |
312 /*Settings for zlib decompression*/ | |
313 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; | |
314 struct LodePNGDecompressSettings { | |
315 /* Check LodePNGDecoderSettings for more ignorable errors such as ignore_crc */ | |
316 unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ | |
317 unsigned ignore_nlen; /*ignore complement of len checksum in uncompressed blocks*/ | |
318 | |
319 /*Maximum decompressed size, beyond this the decoder may (and is encouraged to) stop decoding, | |
320 return an error, output a data size > max_output_size and all the data up to that point. This is | |
321 not hard limit nor a guarantee, but can prevent excessive memory usage. This setting is | |
322 ignored by the PNG decoder, but is used by the deflate/zlib decoder and can be used by custom ones. | |
323 Set to 0 to impose no limit (the default).*/ | |
324 size_t max_output_size; | |
325 | |
326 /*use custom zlib decoder instead of built in one (default: null). | |
327 Should return 0 if success, any non-0 if error (numeric value not exposed).*/ | |
328 unsigned (*custom_zlib)(unsigned char**, size_t*, | |
329 const unsigned char*, size_t, | |
330 const LodePNGDecompressSettings*); | |
331 /*use custom deflate decoder instead of built in one (default: null) | |
332 if custom_zlib is not null, custom_inflate is ignored (the zlib format uses deflate). | |
333 Should return 0 if success, any non-0 if error (numeric value not exposed).*/ | |
334 unsigned (*custom_inflate)(unsigned char**, size_t*, | |
335 const unsigned char*, size_t, | |
336 const LodePNGDecompressSettings*); | |
337 | |
338 const void* custom_context; /*optional custom settings for custom functions*/ | |
339 }; | |
340 | |
341 extern const LodePNGDecompressSettings lodepng_default_decompress_settings; | |
342 void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings); | |
343 #endif /*LODEPNG_COMPILE_DECODER*/ | |
344 | |
345 #ifdef LODEPNG_COMPILE_ENCODER | |
346 /* | |
347 Settings for zlib compression. Tweaking these settings tweaks the balance | |
348 between speed and compression ratio. | |
349 */ | |
350 typedef struct LodePNGCompressSettings LodePNGCompressSettings; | |
351 struct LodePNGCompressSettings /*deflate = compress*/ { | |
352 /*LZ77 related settings*/ | |
353 unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/ | |
354 unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ | |
355 unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/ | |
356 unsigned minmatch; /*minimum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ | |
357 unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/ | |
358 unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ | |
359 | |
360 /*use custom zlib encoder instead of built in one (default: null)*/ | |
361 unsigned (*custom_zlib)(unsigned char**, size_t*, | |
362 const unsigned char*, size_t, | |
363 const LodePNGCompressSettings*); | |
364 /*use custom deflate encoder instead of built in one (default: null) | |
365 if custom_zlib is used, custom_deflate is ignored since only the built in | |
366 zlib function will call custom_deflate*/ | |
367 unsigned (*custom_deflate)(unsigned char**, size_t*, | |
368 const unsigned char*, size_t, | |
369 const LodePNGCompressSettings*); | |
370 | |
371 const void* custom_context; /*optional custom settings for custom functions*/ | |
372 }; | |
373 | |
374 extern const LodePNGCompressSettings lodepng_default_compress_settings; | |
375 void lodepng_compress_settings_init(LodePNGCompressSettings* settings); | |
376 #endif /*LODEPNG_COMPILE_ENCODER*/ | |
377 | |
378 #ifdef LODEPNG_COMPILE_PNG | |
379 /* | |
380 Color mode of an image. Contains all information required to decode the pixel | |
381 bits to RGBA colors. This information is the same as used in the PNG file | |
382 format, and is used both for PNG and raw image data in LodePNG. | |
383 */ | |
384 typedef struct LodePNGColorMode { | |
385 /*header (IHDR)*/ | |
386 LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/ | |
387 unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ | |
388 | |
389 /* | |
390 palette (PLTE and tRNS) | |
391 | |
392 Dynamically allocated with the colors of the palette, including alpha. | |
393 This field may not be allocated directly, use lodepng_color_mode_init first, | |
394 then lodepng_palette_add per color to correctly initialize it (to ensure size | |
395 of exactly 1024 bytes). | |
396 | |
397 The alpha channels must be set as well, set them to 255 for opaque images. | |
398 | |
399 When decoding, with the default settings you can ignore this palette, since | |
400 LodePNG already fills the palette colors in the pixels of the raw RGBA output, | |
401 but when decoding to the original PNG color mode it is needed to reconstruct | |
402 the colors. | |
403 | |
404 The palette is only supported for color type 3. | |
405 */ | |
406 unsigned char* palette; /*palette in RGBARGBA... order. Must be either 0, or when allocated must have 1024 bytes*/ | |
407 size_t palettesize; /*palette size in number of colors (amount of used bytes is 4 * palettesize)*/ | |
408 | |
409 /* | |
410 transparent color key (tRNS) | |
411 | |
412 This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit. | |
413 For grayscale PNGs, r, g and b will all 3 be set to the same. | |
414 | |
415 When decoding, by default you can ignore this information, since LodePNG sets | |
416 pixels with this key to transparent already in the raw RGBA output. | |
417 | |
418 The color key is only supported for color types 0 and 2. | |
419 */ | |
420 unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ | |
421 unsigned key_r; /*red/grayscale component of color key*/ | |
422 unsigned key_g; /*green component of color key*/ | |
423 unsigned key_b; /*blue component of color key*/ | |
424 } LodePNGColorMode; | |
425 | |
426 /*init, cleanup and copy functions to use with this struct*/ | |
427 void lodepng_color_mode_init(LodePNGColorMode* info); | |
428 void lodepng_color_mode_cleanup(LodePNGColorMode* info); | |
429 /*return value is error code (0 means no error)*/ | |
430 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source); | |
431 /* Makes a temporary LodePNGColorMode that does not need cleanup (no palette) */ | |
432 LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth); | |
433 | |
434 void lodepng_palette_clear(LodePNGColorMode* info); | |
435 /*add 1 color to the palette*/ | |
436 unsigned lodepng_palette_add(LodePNGColorMode* info, | |
437 unsigned char r, unsigned char g, unsigned char b, unsigned char a); | |
438 | |
439 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ | |
440 unsigned lodepng_get_bpp(const LodePNGColorMode* info); | |
441 /*get the amount of color channels used, based on colortype in the struct. | |
442 If a palette is used, it counts as 1 channel.*/ | |
443 unsigned lodepng_get_channels(const LodePNGColorMode* info); | |
444 /*is it a grayscale type? (only colortype 0 or 4)*/ | |
445 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info); | |
446 /*has it got an alpha channel? (only colortype 2 or 6)*/ | |
447 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info); | |
448 /*has it got a palette? (only colortype 3)*/ | |
449 unsigned lodepng_is_palette_type(const LodePNGColorMode* info); | |
450 /*only returns true if there is a palette and there is a value in the palette with alpha < 255. | |
451 Loops through the palette to check this.*/ | |
452 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info); | |
453 /* | |
454 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image. | |
455 Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels). | |
456 Returns false if the image can only have opaque pixels. | |
457 In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values, | |
458 or if "key_defined" is true. | |
459 */ | |
460 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info); | |
461 /*Returns the byte size of a raw image buffer with given width, height and color mode*/ | |
462 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color); | |
463 | |
464 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
465 /*The information of a Time chunk in PNG.*/ | |
466 typedef struct LodePNGTime { | |
467 unsigned year; /*2 bytes used (0-65535)*/ | |
468 unsigned month; /*1-12*/ | |
469 unsigned day; /*1-31*/ | |
470 unsigned hour; /*0-23*/ | |
471 unsigned minute; /*0-59*/ | |
472 unsigned second; /*0-60 (to allow for leap seconds)*/ | |
473 } LodePNGTime; | |
474 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
475 | |
476 /*Information about the PNG image, except pixels, width and height.*/ | |
477 typedef struct LodePNGInfo { | |
478 /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ | |
479 unsigned compression_method;/*compression method of the original file. Always 0.*/ | |
480 unsigned filter_method; /*filter method of the original file*/ | |
481 unsigned interlace_method; /*interlace method of the original file: 0=none, 1=Adam7*/ | |
482 LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/ | |
483 | |
484 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
485 /* | |
486 Suggested background color chunk (bKGD) | |
487 | |
488 This uses the same color mode and bit depth as the PNG (except no alpha channel), | |
489 with values truncated to the bit depth in the unsigned integer. | |
490 | |
491 For grayscale and palette PNGs, the value is stored in background_r. The values | |
492 in background_g and background_b are then unused. The decoder will set them | |
493 equal to background_r, the encoder ignores them in this case. | |
494 | |
495 When decoding, you may get these in a different color mode than the one you requested | |
496 for the raw pixels: the colortype and bitdepth defined by info_png.color, that is the | |
497 ones defined in the header of the PNG image, are used. | |
498 | |
499 When encoding with auto_convert, you must use the color model defined in info_png.color for | |
500 these values. The encoder normally ignores info_png.color when auto_convert is on, but will | |
501 use it to interpret these values (and convert copies of them to its chosen color model). | |
502 | |
503 When encoding, avoid setting this to an expensive color, such as a non-gray value | |
504 when the image is gray, or the compression will be worse since it will be forced to | |
505 write the PNG with a more expensive color mode (when auto_convert is on). | |
506 | |
507 The decoder does not use this background color to edit the color of pixels. This is a | |
508 completely optional metadata feature. | |
509 */ | |
510 unsigned background_defined; /*is a suggested background color given?*/ | |
511 unsigned background_r; /*red/gray/palette component of suggested background color*/ | |
512 unsigned background_g; /*green component of suggested background color*/ | |
513 unsigned background_b; /*blue component of suggested background color*/ | |
514 | |
515 /* | |
516 Non-international text chunks (tEXt and zTXt) | |
517 | |
518 The char** arrays each contain num strings. The actual messages are in | |
519 text_strings, while text_keys are keywords that give a short description what | |
520 the actual text represents, e.g. Title, Author, Description, or anything else. | |
521 | |
522 All the string fields below including strings, keys, names and language tags are null terminated. | |
523 The PNG specification uses null characters for the keys, names and tags, and forbids null | |
524 characters to appear in the main text which is why we can use null termination everywhere here. | |
525 | |
526 A keyword is minimum 1 character and maximum 79 characters long (plus the | |
527 additional null terminator). It's discouraged to use a single line length | |
528 longer than 79 characters for texts. | |
529 | |
530 Don't allocate these text buffers yourself. Use the init/cleanup functions | |
531 correctly and use lodepng_add_text and lodepng_clear_text. | |
532 | |
533 Standard text chunk keywords and strings are encoded using Latin-1. | |
534 */ | |
535 size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/ | |
536 char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/ | |
537 char** text_strings; /*the actual text*/ | |
538 | |
539 /* | |
540 International text chunks (iTXt) | |
541 Similar to the non-international text chunks, but with additional strings | |
542 "langtags" and "transkeys", and the following text encodings are used: | |
543 keys: Latin-1, langtags: ASCII, transkeys and strings: UTF-8. | |
544 keys must be 1-79 characters (plus the additional null terminator), the other | |
545 strings are any length. | |
546 */ | |
547 size_t itext_num; /*the amount of international texts in this PNG*/ | |
548 char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ | |
549 char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/ | |
550 char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/ | |
551 char** itext_strings; /*the actual international text - UTF-8 string*/ | |
552 | |
553 /*time chunk (tIME)*/ | |
554 unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ | |
555 LodePNGTime time; | |
556 | |
557 /*phys chunk (pHYs)*/ | |
558 unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/ | |
559 unsigned phys_x; /*pixels per unit in x direction*/ | |
560 unsigned phys_y; /*pixels per unit in y direction*/ | |
561 unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ | |
562 | |
563 /* | |
564 Color profile related chunks: gAMA, cHRM, sRGB, iCPP, sBIT | |
565 | |
566 LodePNG does not apply any color conversions on pixels in the encoder or decoder and does not interpret these color | |
567 profile values. It merely passes on the information. If you wish to use color profiles and convert colors, please | |
568 use these values with a color management library. | |
569 | |
570 See the PNG, ICC and sRGB specifications for more information about the meaning of these values. | |
571 */ | |
572 | |
573 /* gAMA chunk: optional, overridden by sRGB or iCCP if those are present. */ | |
574 unsigned gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */ | |
575 unsigned gama_gamma; /* Gamma exponent times 100000 */ | |
576 | |
577 /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */ | |
578 unsigned chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */ | |
579 unsigned chrm_white_x; /* White Point x times 100000 */ | |
580 unsigned chrm_white_y; /* White Point y times 100000 */ | |
581 unsigned chrm_red_x; /* Red x times 100000 */ | |
582 unsigned chrm_red_y; /* Red y times 100000 */ | |
583 unsigned chrm_green_x; /* Green x times 100000 */ | |
584 unsigned chrm_green_y; /* Green y times 100000 */ | |
585 unsigned chrm_blue_x; /* Blue x times 100000 */ | |
586 unsigned chrm_blue_y; /* Blue y times 100000 */ | |
587 | |
588 /* | |
589 sRGB chunk: optional. May not appear at the same time as iCCP. | |
590 If gAMA is also present gAMA must contain value 45455. | |
591 If cHRM is also present cHRM must contain respectively 31270,32900,64000,33000,30000,60000,15000,6000. | |
592 */ | |
593 unsigned srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */ | |
594 unsigned srgb_intent; /* Rendering intent: 0=perceptual, 1=rel. colorimetric, 2=saturation, 3=abs. colorimetric */ | |
595 | |
596 /* | |
597 iCCP chunk: optional. May not appear at the same time as sRGB. | |
598 | |
599 LodePNG does not parse or use the ICC profile (except its color space header field for an edge case), a | |
600 separate library to handle the ICC data (not included in LodePNG) format is needed to use it for color | |
601 management and conversions. | |
602 | |
603 For encoding, if iCCP is present, gAMA and cHRM are recommended to be added as well with values that match the ICC | |
604 profile as closely as possible, if you wish to do this you should provide the correct values for gAMA and cHRM and | |
605 enable their '_defined' flags since LodePNG will not automatically compute them from the ICC profile. | |
606 | |
607 For encoding, the ICC profile is required by the PNG specification to be an "RGB" profile for non-gray | |
608 PNG color types and a "GRAY" profile for gray PNG color types. If you disable auto_convert, you must ensure | |
609 the ICC profile type matches your requested color type, else the encoder gives an error. If auto_convert is | |
610 enabled (the default), and the ICC profile is not a good match for the pixel data, this will result in an encoder | |
611 error if the pixel data has non-gray pixels for a GRAY profile, or a silent less-optimal compression of the pixel | |
612 data if the pixels could be encoded as grayscale but the ICC profile is RGB. | |
613 | |
614 To avoid this do not set an ICC profile in the image unless there is a good reason for it, and when doing so | |
615 make sure you compute it carefully to avoid the above problems. | |
616 */ | |
617 unsigned iccp_defined; /* Whether an iCCP chunk is present (0 = not present, 1 = present). */ | |
618 char* iccp_name; /* Null terminated string with profile name, 1-79 bytes */ | |
619 /* | |
620 The ICC profile in iccp_profile_size bytes. | |
621 Don't allocate this buffer yourself. Use the init/cleanup functions | |
622 correctly and use lodepng_set_icc and lodepng_clear_icc. | |
623 */ | |
624 unsigned char* iccp_profile; | |
625 unsigned iccp_profile_size; /* The size of iccp_profile in bytes */ | |
626 | |
627 /* | |
628 sBIT chunk: significant bits. Optional metadata, only set this if needed. | |
629 | |
630 If defined, these values give the bit depth of the original data. Since PNG only stores 1, 2, 4, 8 or 16-bit | |
631 per channel data, the significant bits value can be used to indicate the original encoded data has another | |
632 sample depth, such as 10 or 12. | |
633 | |
634 Encoders using this value, when storing the pixel data, should use the most significant bits | |
635 of the data to store the original bits, and use a good sample depth scaling method such as | |
636 "left bit replication" to fill in the least significant bits, rather than fill zeroes. | |
637 | |
638 Decoders using this value, if able to work with data that's e.g. 10-bit or 12-bit, should right | |
639 shift the data to go back to the original bit depth, but decoders are also allowed to ignore | |
640 sbit and work e.g. with the 8-bit or 16-bit data from the PNG directly, since thanks | |
641 to the encoder contract, the values encoded in PNG are in valid range for the PNG bit depth. | |
642 | |
643 For grayscale images, sbit_g and sbit_b are not used, and for images that don't use color | |
644 type RGBA or grayscale+alpha, sbit_a is not used (it's not used even for palette images with | |
645 translucent palette values, or images with color key). The values that are used must be | |
646 greater than zero and smaller than or equal to the PNG bit depth. | |
647 | |
648 The color type from the header in the PNG image defines these used and unused fields: if | |
649 decoding with a color mode conversion, such as always decoding to RGBA, this metadata still | |
650 only uses the color type of the original PNG, and may e.g. lack the alpha channel info | |
651 if the PNG was RGB. When encoding with auto_convert (as well as without), also always the | |
652 color model defined in info_png.color determines this. | |
653 | |
654 NOTE: enabling sbit can hurt compression, because the encoder can then not always use | |
655 auto_convert to choose a more optimal color mode for the data, because the PNG format has | |
656 strict requirements for the allowed sbit values in combination with color modes. | |
657 For example, setting these fields to 10-bit will force the encoder to keep using a 16-bit per channel | |
658 color mode, even if the pixel data would in fact fit in a more efficient 8-bit mode. | |
659 */ | |
660 unsigned sbit_defined; /*is significant bits given? if not, the values below are unused*/ | |
661 unsigned sbit_r; /*red or gray component of significant bits*/ | |
662 unsigned sbit_g; /*green component of significant bits*/ | |
663 unsigned sbit_b; /*blue component of significant bits*/ | |
664 unsigned sbit_a; /*alpha component of significant bits*/ | |
665 | |
666 /* End of color profile related chunks */ | |
667 | |
668 | |
669 /* | |
670 unknown chunks: chunks not known by LodePNG, passed on byte for byte. | |
671 | |
672 There are 3 buffers, one for each position in the PNG where unknown chunks can appear. | |
673 Each buffer contains all unknown chunks for that position consecutively. | |
674 The 3 positions are: | |
675 0: between IHDR and PLTE, 1: between PLTE and IDAT, 2: between IDAT and IEND. | |
676 | |
677 For encoding, do not store critical chunks or known chunks that are enabled with a "_defined" flag | |
678 above in here, since the encoder will blindly follow this and could then encode an invalid PNG file | |
679 (such as one with two IHDR chunks or the disallowed combination of sRGB with iCCP). But do use | |
680 this if you wish to store an ancillary chunk that is not supported by LodePNG (such as sPLT or hIST), | |
681 or any non-standard PNG chunk. | |
682 | |
683 Do not allocate or traverse this data yourself. Use the chunk traversing functions declared | |
684 later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct. | |
685 */ | |
686 unsigned char* unknown_chunks_data[3]; | |
687 size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ | |
688 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
689 } LodePNGInfo; | |
690 | |
691 /*init, cleanup and copy functions to use with this struct*/ | |
692 void lodepng_info_init(LodePNGInfo* info); | |
693 void lodepng_info_cleanup(LodePNGInfo* info); | |
694 /*return value is error code (0 means no error)*/ | |
695 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source); | |
696 | |
697 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
698 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/ | |
699 void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ | |
700 | |
701 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag, | |
702 const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/ | |
703 void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ | |
704 | |
705 /*replaces if exists*/ | |
706 unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size); | |
707 void lodepng_clear_icc(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ | |
708 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
709 | |
710 /* | |
711 Converts raw buffer from one color type to another color type, based on | |
712 LodePNGColorMode structs to describe the input and output color type. | |
713 See the reference manual at the end of this header file to see which color conversions are supported. | |
714 return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported) | |
715 The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel | |
716 of the output color type (lodepng_get_bpp). | |
717 For < 8 bpp images, there should not be padding bits at the end of scanlines. | |
718 For 16-bit per channel colors, uses big endian format like PNG does. | |
719 Return value is LodePNG error code | |
720 */ | |
721 unsigned lodepng_convert(unsigned char* out, const unsigned char* in, | |
722 const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in, | |
723 unsigned w, unsigned h); | |
724 | |
725 #ifdef LODEPNG_COMPILE_DECODER | |
726 /* | |
727 Settings for the decoder. This contains settings for the PNG and the Zlib | |
728 decoder, but not the Info settings from the Info structs. | |
729 */ | |
730 typedef struct LodePNGDecoderSettings { | |
731 LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ | |
732 | |
733 /* Check LodePNGDecompressSettings for more ignorable errors such as ignore_adler32 */ | |
734 unsigned ignore_crc; /*ignore CRC checksums*/ | |
735 unsigned ignore_critical; /*ignore unknown critical chunks*/ | |
736 unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/ | |
737 /* TODO: make a system involving warnings with levels and a strict mode instead. Other potentially recoverable | |
738 errors: srgb rendering intent value, size of content of ancillary chunks, more than 79 characters for some | |
739 strings, placement/combination rules for ancillary chunks, crc of unknown chunks, allowed characters | |
740 in string keys, etc... */ | |
741 | |
742 unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ | |
743 | |
744 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
745 unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/ | |
746 | |
747 /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/ | |
748 unsigned remember_unknown_chunks; | |
749 | |
750 /* maximum size for decompressed text chunks. If a text chunk's text is larger than this, an error is returned, | |
751 unless reading text chunks is disabled or this limit is set higher or disabled. Set to 0 to allow any size. | |
752 By default it is a value that prevents unreasonably large strings from hogging memory. */ | |
753 size_t max_text_size; | |
754 | |
755 /* maximum size for compressed ICC chunks. If the ICC profile is larger than this, an error will be returned. Set to | |
756 0 to allow any size. By default this is a value that prevents ICC profiles that would be much larger than any | |
757 legitimate profile could be to hog memory. */ | |
758 size_t max_icc_size; | |
759 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
760 } LodePNGDecoderSettings; | |
761 | |
762 void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); | |
763 #endif /*LODEPNG_COMPILE_DECODER*/ | |
764 | |
765 #ifdef LODEPNG_COMPILE_ENCODER | |
766 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ | |
767 typedef enum LodePNGFilterStrategy { | |
768 /*every filter at zero*/ | |
769 LFS_ZERO = 0, | |
770 /*every filter at 1, 2, 3 or 4 (paeth), unlike LFS_ZERO not a good choice, but for testing*/ | |
771 LFS_ONE = 1, | |
772 LFS_TWO = 2, | |
773 LFS_THREE = 3, | |
774 LFS_FOUR = 4, | |
775 /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/ | |
776 LFS_MINSUM, | |
777 /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending | |
778 on the image, this is better or worse than minsum.*/ | |
779 LFS_ENTROPY, | |
780 /* | |
781 Brute-force-search PNG filters by compressing each filter for each scanline. | |
782 Experimental, very slow, and only rarely gives better compression than MINSUM. | |
783 */ | |
784 LFS_BRUTE_FORCE, | |
785 /*use predefined_filters buffer: you specify the filter type for each scanline*/ | |
786 LFS_PREDEFINED | |
787 } LodePNGFilterStrategy; | |
788 | |
789 /*Gives characteristics about the integer RGBA colors of the image (count, alpha channel usage, bit depth, ...), | |
790 which helps decide which color model to use for encoding. | |
791 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/ | |
792 typedef struct LodePNGColorStats { | |
793 unsigned colored; /*not grayscale*/ | |
794 unsigned key; /*image is not opaque and color key is possible instead of full alpha*/ | |
795 unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/ | |
796 unsigned short key_g; | |
797 unsigned short key_b; | |
798 unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/ | |
799 unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16 or allow_palette is disabled.*/ | |
800 unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order, only valid when numcolors is valid*/ | |
801 unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for grayscale only. 16 if 16-bit per channel required.*/ | |
802 size_t numpixels; | |
803 | |
804 /*user settings for computing/using the stats*/ | |
805 unsigned allow_palette; /*default 1. if 0, disallow choosing palette colortype in auto_choose_color, and don't count numcolors*/ | |
806 unsigned allow_greyscale; /*default 1. if 0, choose RGB or RGBA even if the image only has gray colors*/ | |
807 } LodePNGColorStats; | |
808 | |
809 void lodepng_color_stats_init(LodePNGColorStats* stats); | |
810 | |
811 /*Get a LodePNGColorStats of the image. The stats must already have been inited. | |
812 Returns error code (e.g. alloc fail) or 0 if ok.*/ | |
813 unsigned lodepng_compute_color_stats(LodePNGColorStats* stats, | |
814 const unsigned char* image, unsigned w, unsigned h, | |
815 const LodePNGColorMode* mode_in); | |
816 | |
817 /*Settings for the encoder.*/ | |
818 typedef struct LodePNGEncoderSettings { | |
819 LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ | |
820 | |
821 unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/ | |
822 | |
823 /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than | |
824 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to | |
825 completely follow the official PNG heuristic, filter_palette_zero must be true and | |
826 filter_strategy must be LFS_MINSUM*/ | |
827 unsigned filter_palette_zero; | |
828 /*Which filter strategy to use when not using zeroes due to filter_palette_zero. | |
829 Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/ | |
830 LodePNGFilterStrategy filter_strategy; | |
831 /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with | |
832 the same length as the amount of scanlines in the image, and each value must <= 5. You | |
833 have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero | |
834 must be set to 0 to ensure this is also used on palette or low bitdepth images.*/ | |
835 const unsigned char* predefined_filters; | |
836 | |
837 /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). | |
838 If colortype is 3, PLTE is always created. If color type is explicitely set | |
839 to a grayscale type (1 or 4), this is not done and is ignored. If enabling this, | |
840 a palette must be present in the info_png. | |
841 NOTE: enabling this may worsen compression if auto_convert is used to choose | |
842 optimal color mode, because it cannot use grayscale color modes in this case*/ | |
843 unsigned force_palette; | |
844 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
845 /*add LodePNG identifier and version as a text chunk, for debugging*/ | |
846 unsigned add_id; | |
847 /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ | |
848 unsigned text_compression; | |
849 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
850 } LodePNGEncoderSettings; | |
851 | |
852 void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); | |
853 #endif /*LODEPNG_COMPILE_ENCODER*/ | |
854 | |
855 | |
856 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) | |
857 /*The settings, state and information for extended encoding and decoding.*/ | |
858 typedef struct LodePNGState { | |
859 #ifdef LODEPNG_COMPILE_DECODER | |
860 LodePNGDecoderSettings decoder; /*the decoding settings*/ | |
861 #endif /*LODEPNG_COMPILE_DECODER*/ | |
862 #ifdef LODEPNG_COMPILE_ENCODER | |
863 LodePNGEncoderSettings encoder; /*the encoding settings*/ | |
864 #endif /*LODEPNG_COMPILE_ENCODER*/ | |
865 LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ | |
866 LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/ | |
867 unsigned error; | |
868 } LodePNGState; | |
869 | |
870 /*init, cleanup and copy functions to use with this struct*/ | |
871 void lodepng_state_init(LodePNGState* state); | |
872 void lodepng_state_cleanup(LodePNGState* state); | |
873 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source); | |
874 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */ | |
875 | |
876 #ifdef LODEPNG_COMPILE_DECODER | |
877 /* | |
878 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and | |
879 getting much more information about the PNG image and color mode. | |
880 */ | |
881 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, | |
882 LodePNGState* state, | |
883 const unsigned char* in, size_t insize); | |
884 | |
885 /* | |
886 Read the PNG header, but not the actual data. This returns only the information | |
887 that is in the IHDR chunk of the PNG, such as width, height and color type. The | |
888 information is placed in the info_png field of the LodePNGState. | |
889 */ | |
890 unsigned lodepng_inspect(unsigned* w, unsigned* h, | |
891 LodePNGState* state, | |
892 const unsigned char* in, size_t insize); | |
893 #endif /*LODEPNG_COMPILE_DECODER*/ | |
894 | |
895 /* | |
896 Reads one metadata chunk (other than IHDR, which is handled by lodepng_inspect) | |
897 of the PNG file and outputs what it read in the state. Returns error code on failure. | |
898 Use lodepng_inspect first with a new state, then e.g. lodepng_chunk_find_const | |
899 to find the desired chunk type, and if non null use lodepng_inspect_chunk (with | |
900 chunk_pointer - start_of_file as pos). | |
901 Supports most metadata chunks from the PNG standard (gAMA, bKGD, tEXt, ...). | |
902 Ignores unsupported, unknown, non-metadata or IHDR chunks (without error). | |
903 Requirements: &in[pos] must point to start of a chunk, must use regular | |
904 lodepng_inspect first since format of most other chunks depends on IHDR, and if | |
905 there is a PLTE chunk, that one must be inspected before tRNS or bKGD. | |
906 */ | |
907 unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos, | |
908 const unsigned char* in, size_t insize); | |
909 | |
910 #ifdef LODEPNG_COMPILE_ENCODER | |
911 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ | |
912 unsigned lodepng_encode(unsigned char** out, size_t* outsize, | |
913 const unsigned char* image, unsigned w, unsigned h, | |
914 LodePNGState* state); | |
915 #endif /*LODEPNG_COMPILE_ENCODER*/ | |
916 | |
917 /* | |
918 The lodepng_chunk functions are normally not needed, except to traverse the | |
919 unknown chunks stored in the LodePNGInfo struct, or add new ones to it. | |
920 It also allows traversing the chunks of an encoded PNG file yourself. | |
921 | |
922 The chunk pointer always points to the beginning of the chunk itself, that is | |
923 the first byte of the 4 length bytes. | |
924 | |
925 In the PNG file format, chunks have the following format: | |
926 -4 bytes length: length of the data of the chunk in bytes (chunk itself is 12 bytes longer) | |
927 -4 bytes chunk type (ASCII a-z,A-Z only, see below) | |
928 -length bytes of data (may be 0 bytes if length was 0) | |
929 -4 bytes of CRC, computed on chunk name + data | |
930 | |
931 The first chunk starts at the 8th byte of the PNG file, the entire rest of the file | |
932 exists out of concatenated chunks with the above format. | |
933 | |
934 PNG standard chunk ASCII naming conventions: | |
935 -First byte: uppercase = critical, lowercase = ancillary | |
936 -Second byte: uppercase = public, lowercase = private | |
937 -Third byte: must be uppercase | |
938 -Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy | |
939 */ | |
940 | |
941 /* | |
942 Gets the length of the data of the chunk. Total chunk length has 12 bytes more. | |
943 There must be at least 4 bytes to read from. If the result value is too large, | |
944 it may be corrupt data. | |
945 */ | |
946 unsigned lodepng_chunk_length(const unsigned char* chunk); | |
947 | |
948 /*puts the 4-byte type in null terminated string*/ | |
949 void lodepng_chunk_type(char type[5], const unsigned char* chunk); | |
950 | |
951 /*check if the type is the given type*/ | |
952 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type); | |
953 | |
954 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ | |
955 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk); | |
956 | |
957 /*0: public, 1: private (see PNG standard)*/ | |
958 unsigned char lodepng_chunk_private(const unsigned char* chunk); | |
959 | |
960 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ | |
961 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk); | |
962 | |
963 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/ | |
964 unsigned char* lodepng_chunk_data(unsigned char* chunk); | |
965 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk); | |
966 | |
967 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ | |
968 unsigned lodepng_chunk_check_crc(const unsigned char* chunk); | |
969 | |
970 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ | |
971 void lodepng_chunk_generate_crc(unsigned char* chunk); | |
972 | |
973 /* | |
974 Iterate to next chunks, allows iterating through all chunks of the PNG file. | |
975 Input must be at the beginning of a chunk (result of a previous lodepng_chunk_next call, | |
976 or the 8th byte of a PNG file which always has the first chunk), or alternatively may | |
977 point to the first byte of the PNG file (which is not a chunk but the magic header, the | |
978 function will then skip over it and return the first real chunk). | |
979 Will output pointer to the start of the next chunk, or at or beyond end of the file if there | |
980 is no more chunk after this or possibly if the chunk is corrupt. | |
981 Start this process at the 8th byte of the PNG file. | |
982 In a non-corrupt PNG file, the last chunk should have name "IEND". | |
983 */ | |
984 unsigned char* lodepng_chunk_next(unsigned char* chunk, unsigned char* end); | |
985 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk, const unsigned char* end); | |
986 | |
987 /*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/ | |
988 unsigned char* lodepng_chunk_find(unsigned char* chunk, unsigned char* end, const char type[5]); | |
989 const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]); | |
990 | |
991 /* | |
992 Appends chunk to the data in out. The given chunk should already have its chunk header. | |
993 The out variable and outsize are updated to reflect the new reallocated buffer. | |
994 Returns error code (0 if it went ok) | |
995 */ | |
996 unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk); | |
997 | |
998 /* | |
999 Appends new chunk to out. The chunk to append is given by giving its length, type | |
1000 and data separately. The type is a 4-letter string. | |
1001 The out variable and outsize are updated to reflect the new reallocated buffer. | |
1002 Returne error code (0 if it went ok) | |
1003 */ | |
1004 unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length, | |
1005 const char* type, const unsigned char* data); | |
1006 | |
1007 | |
1008 /*Calculate CRC32 of buffer*/ | |
1009 unsigned lodepng_crc32(const unsigned char* buf, size_t len); | |
1010 #endif /*LODEPNG_COMPILE_PNG*/ | |
1011 | |
1012 | |
1013 #ifdef LODEPNG_COMPILE_ZLIB | |
1014 /* | |
1015 This zlib part can be used independently to zlib compress and decompress a | |
1016 buffer. It cannot be used to create gzip files however, and it only supports the | |
1017 part of zlib that is required for PNG, it does not support dictionaries. | |
1018 */ | |
1019 | |
1020 #ifdef LODEPNG_COMPILE_DECODER | |
1021 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/ | |
1022 unsigned lodepng_inflate(unsigned char** out, size_t* outsize, | |
1023 const unsigned char* in, size_t insize, | |
1024 const LodePNGDecompressSettings* settings); | |
1025 | |
1026 /* | |
1027 Decompresses Zlib data. Reallocates the out buffer and appends the data. The | |
1028 data must be according to the zlib specification. | |
1029 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid | |
1030 buffer and *outsize its size in bytes. out must be freed by user after usage. | |
1031 */ | |
1032 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, | |
1033 const unsigned char* in, size_t insize, | |
1034 const LodePNGDecompressSettings* settings); | |
1035 #endif /*LODEPNG_COMPILE_DECODER*/ | |
1036 | |
1037 #ifdef LODEPNG_COMPILE_ENCODER | |
1038 /* | |
1039 Compresses data with Zlib. Reallocates the out buffer and appends the data. | |
1040 Zlib adds a small header and trailer around the deflate data. | |
1041 The data is output in the format of the zlib specification. | |
1042 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid | |
1043 buffer and *outsize its size in bytes. out must be freed by user after usage. | |
1044 */ | |
1045 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, | |
1046 const unsigned char* in, size_t insize, | |
1047 const LodePNGCompressSettings* settings); | |
1048 | |
1049 /* | |
1050 Find length-limited Huffman code for given frequencies. This function is in the | |
1051 public interface only for tests, it's used internally by lodepng_deflate. | |
1052 */ | |
1053 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies, | |
1054 size_t numcodes, unsigned maxbitlen); | |
1055 | |
1056 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ | |
1057 unsigned lodepng_deflate(unsigned char** out, size_t* outsize, | |
1058 const unsigned char* in, size_t insize, | |
1059 const LodePNGCompressSettings* settings); | |
1060 | |
1061 #endif /*LODEPNG_COMPILE_ENCODER*/ | |
1062 #endif /*LODEPNG_COMPILE_ZLIB*/ | |
1063 | |
1064 #ifdef LODEPNG_COMPILE_DISK | |
1065 /* | |
1066 Load a file from disk into buffer. The function allocates the out buffer, and | |
1067 after usage you should free it. | |
1068 out: output parameter, contains pointer to loaded buffer. | |
1069 outsize: output parameter, size of the allocated out buffer | |
1070 filename: the path to the file to load | |
1071 return value: error code (0 means ok) | |
1072 | |
1073 NOTE: Wide-character filenames are not supported, you can use an external method | |
1074 to handle such files and decode in-memory. | |
1075 */ | |
1076 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename); | |
1077 | |
1078 /* | |
1079 Save a file from buffer to disk. Warning, if it exists, this function overwrites | |
1080 the file without warning! | |
1081 buffer: the buffer to write | |
1082 buffersize: size of the buffer to write | |
1083 filename: the path to the file to save to | |
1084 return value: error code (0 means ok) | |
1085 | |
1086 NOTE: Wide-character filenames are not supported, you can use an external method | |
1087 to handle such files and encode in-memory | |
1088 */ | |
1089 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename); | |
1090 #endif /*LODEPNG_COMPILE_DISK*/ | |
1091 | |
1092 #ifdef LODEPNG_COMPILE_CPP | |
1093 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */ | |
1094 namespace lodepng { | |
1095 #ifdef LODEPNG_COMPILE_PNG | |
1096 class State : public LodePNGState { | |
1097 public: | |
1098 State(); | |
1099 State(const State& other); | |
1100 ~State(); | |
1101 State& operator=(const State& other); | |
1102 }; | |
1103 | |
1104 #ifdef LODEPNG_COMPILE_DECODER | |
1105 /* Same as other lodepng::decode, but using a State for more settings and information. */ | |
1106 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, | |
1107 State& state, | |
1108 const unsigned char* in, size_t insize); | |
1109 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, | |
1110 State& state, | |
1111 const std::vector<unsigned char>& in); | |
1112 #endif /*LODEPNG_COMPILE_DECODER*/ | |
1113 | |
1114 #ifdef LODEPNG_COMPILE_ENCODER | |
1115 /* Same as other lodepng::encode, but using a State for more settings and information. */ | |
1116 unsigned encode(std::vector<unsigned char>& out, | |
1117 const unsigned char* in, unsigned w, unsigned h, | |
1118 State& state); | |
1119 unsigned encode(std::vector<unsigned char>& out, | |
1120 const std::vector<unsigned char>& in, unsigned w, unsigned h, | |
1121 State& state); | |
1122 #endif /*LODEPNG_COMPILE_ENCODER*/ | |
1123 | |
1124 #ifdef LODEPNG_COMPILE_DISK | |
1125 /* | |
1126 Load a file from disk into an std::vector. | |
1127 return value: error code (0 means ok) | |
1128 | |
1129 NOTE: Wide-character filenames are not supported, you can use an external method | |
1130 to handle such files and decode in-memory | |
1131 */ | |
1132 unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename); | |
1133 | |
1134 /* | |
1135 Save the binary data in an std::vector to a file on disk. The file is overwritten | |
1136 without warning. | |
1137 | |
1138 NOTE: Wide-character filenames are not supported, you can use an external method | |
1139 to handle such files and encode in-memory | |
1140 */ | |
1141 unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename); | |
1142 #endif /* LODEPNG_COMPILE_DISK */ | |
1143 #endif /* LODEPNG_COMPILE_PNG */ | |
1144 | |
1145 #ifdef LODEPNG_COMPILE_ZLIB | |
1146 #ifdef LODEPNG_COMPILE_DECODER | |
1147 /* Zlib-decompress an unsigned char buffer */ | |
1148 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, | |
1149 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); | |
1150 | |
1151 /* Zlib-decompress an std::vector */ | |
1152 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, | |
1153 const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); | |
1154 #endif /* LODEPNG_COMPILE_DECODER */ | |
1155 | |
1156 #ifdef LODEPNG_COMPILE_ENCODER | |
1157 /* Zlib-compress an unsigned char buffer */ | |
1158 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, | |
1159 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); | |
1160 | |
1161 /* Zlib-compress an std::vector */ | |
1162 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, | |
1163 const LodePNGCompressSettings& settings = lodepng_default_compress_settings); | |
1164 #endif /* LODEPNG_COMPILE_ENCODER */ | |
1165 #endif /* LODEPNG_COMPILE_ZLIB */ | |
1166 } /* namespace lodepng */ | |
1167 #endif /*LODEPNG_COMPILE_CPP*/ | |
1168 | |
1169 /* | |
1170 TODO: | |
1171 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often | |
1172 [.] check compatibility with various compilers - done but needs to be redone for every newer version | |
1173 [X] converting color to 16-bit per channel types | |
1174 [X] support color profile chunk types (but never let them touch RGB values by default) | |
1175 [ ] support all public PNG chunk types (almost done except sPLT and hIST) | |
1176 [ ] make sure encoder generates no chunks with size > (2^31)-1 | |
1177 [ ] partial decoding (stream processing) | |
1178 [X] let the "isFullyOpaque" function check color keys and transparent palettes too | |
1179 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl" | |
1180 [ ] allow treating some errors like warnings, when image is recoverable (e.g. 69, 57, 58) | |
1181 [ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ... | |
1182 [ ] error messages with line numbers (and version) | |
1183 [ ] errors in state instead of as return code? | |
1184 [ ] new errors/warnings like suspiciously big decompressed ztxt or iccp chunk | |
1185 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes | |
1186 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ... | |
1187 [ ] allow user to give data (void*) to custom allocator | |
1188 [X] provide alternatives for C library functions not present on some platforms (memcpy, ...) | |
1189 */ | |
1190 | |
1191 #endif /*LODEPNG_H inclusion guard*/ | |
1192 | |
1193 /* | |
1194 LodePNG Documentation | |
1195 --------------------- | |
1196 | |
1197 0. table of contents | |
1198 -------------------- | |
1199 | |
1200 1. about | |
1201 1.1. supported features | |
1202 1.2. features not supported | |
1203 2. C and C++ version | |
1204 3. security | |
1205 4. decoding | |
1206 5. encoding | |
1207 6. color conversions | |
1208 6.1. PNG color types | |
1209 6.2. color conversions | |
1210 6.3. padding bits | |
1211 6.4. A note about 16-bits per channel and endianness | |
1212 7. error values | |
1213 8. chunks and PNG editing | |
1214 9. compiler support | |
1215 10. examples | |
1216 10.1. decoder C++ example | |
1217 10.2. decoder C example | |
1218 11. state settings reference | |
1219 12. changes | |
1220 13. contact information | |
1221 | |
1222 | |
1223 1. about | |
1224 -------- | |
1225 | |
1226 PNG is a file format to store raster images losslessly with good compression, | |
1227 supporting different color types and alpha channel. | |
1228 | |
1229 LodePNG is a PNG codec according to the Portable Network Graphics (PNG) | |
1230 Specification (Second Edition) - W3C Recommendation 10 November 2003. | |
1231 | |
1232 The specifications used are: | |
1233 | |
1234 *) Portable Network Graphics (PNG) Specification (Second Edition): | |
1235 http://www.w3.org/TR/2003/REC-PNG-20031110 | |
1236 *) RFC 1950 ZLIB Compressed Data Format version 3.3: | |
1237 http://www.gzip.org/zlib/rfc-zlib.html | |
1238 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3: | |
1239 http://www.gzip.org/zlib/rfc-deflate.html | |
1240 | |
1241 The most recent version of LodePNG can currently be found at | |
1242 http://lodev.org/lodepng/ | |
1243 | |
1244 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds | |
1245 extra functionality. | |
1246 | |
1247 LodePNG exists out of two files: | |
1248 -lodepng.h: the header file for both C and C++ | |
1249 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage | |
1250 | |
1251 If you want to start using LodePNG right away without reading this doc, get the | |
1252 examples from the LodePNG website to see how to use it in code, or check the | |
1253 smaller examples in chapter 13 here. | |
1254 | |
1255 LodePNG is simple but only supports the basic requirements. To achieve | |
1256 simplicity, the following design choices were made: There are no dependencies | |
1257 on any external library. There are functions to decode and encode a PNG with | |
1258 a single function call, and extended versions of these functions taking a | |
1259 LodePNGState struct allowing to specify or get more information. By default | |
1260 the colors of the raw image are always RGB or RGBA, no matter what color type | |
1261 the PNG file uses. To read and write files, there are simple functions to | |
1262 convert the files to/from buffers in memory. | |
1263 | |
1264 This all makes LodePNG suitable for loading textures in games, demos and small | |
1265 programs, ... It's less suitable for full fledged image editors, loading PNGs | |
1266 over network (it requires all the image data to be available before decoding can | |
1267 begin), life-critical systems, ... | |
1268 | |
1269 1.1. supported features | |
1270 ----------------------- | |
1271 | |
1272 The following features are supported by the decoder: | |
1273 | |
1274 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image, | |
1275 or the same color type as the PNG | |
1276 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image | |
1277 *) Adam7 interlace and deinterlace for any color type | |
1278 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk | |
1279 *) support for alpha channels, including RGBA color model, translucent palettes and color keying | |
1280 *) zlib decompression (inflate) | |
1281 *) zlib compression (deflate) | |
1282 *) CRC32 and ADLER32 checksums | |
1283 *) colorimetric color profile conversions: currently experimentally available in lodepng_util.cpp only, | |
1284 plus alternatively ability to pass on chroma/gamma/ICC profile information to other color management system. | |
1285 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks. | |
1286 *) the following chunks are supported by both encoder and decoder: | |
1287 IHDR: header information | |
1288 PLTE: color palette | |
1289 IDAT: pixel data | |
1290 IEND: the final chunk | |
1291 tRNS: transparency for palettized images | |
1292 tEXt: textual information | |
1293 zTXt: compressed textual information | |
1294 iTXt: international textual information | |
1295 bKGD: suggested background color | |
1296 pHYs: physical dimensions | |
1297 tIME: modification time | |
1298 cHRM: RGB chromaticities | |
1299 gAMA: RGB gamma correction | |
1300 iCCP: ICC color profile | |
1301 sRGB: rendering intent | |
1302 sBIT: significant bits | |
1303 | |
1304 1.2. features not supported | |
1305 --------------------------- | |
1306 | |
1307 The following features are not (yet) supported: | |
1308 | |
1309 *) some features needed to make a conformant PNG-Editor might be still missing. | |
1310 *) partial loading/stream processing. All data must be available and is processed in one call. | |
1311 *) The hIST and sPLT public chunks are not (yet) supported but treated as unknown chunks | |
1312 | |
1313 | |
1314 2. C and C++ version | |
1315 -------------------- | |
1316 | |
1317 The C version uses buffers allocated with alloc that you need to free() | |
1318 yourself. You need to use init and cleanup functions for each struct whenever | |
1319 using a struct from the C version to avoid exploits and memory leaks. | |
1320 | |
1321 The C++ version has extra functions with std::vectors in the interface and the | |
1322 lodepng::State class which is a LodePNGState with constructor and destructor. | |
1323 | |
1324 These files work without modification for both C and C++ compilers because all | |
1325 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers | |
1326 ignore it, and the C code is made to compile both with strict ISO C90 and C++. | |
1327 | |
1328 To use the C++ version, you need to rename the source file to lodepng.cpp | |
1329 (instead of lodepng.c), and compile it with a C++ compiler. | |
1330 | |
1331 To use the C version, you need to rename the source file to lodepng.c (instead | |
1332 of lodepng.cpp), and compile it with a C compiler. | |
1333 | |
1334 | |
1335 3. Security | |
1336 ----------- | |
1337 | |
1338 Even if carefully designed, it's always possible that LodePNG contains possible | |
1339 exploits. If you discover one, please let me know, and it will be fixed. | |
1340 | |
1341 When using LodePNG, care has to be taken with the C version of LodePNG, as well | |
1342 as the C-style structs when working with C++. The following conventions are used | |
1343 for all C-style structs: | |
1344 | |
1345 -if a struct has a corresponding init function, always call the init function when making a new one | |
1346 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks | |
1347 -if a struct has a corresponding copy function, use the copy function instead of "=". | |
1348 The destination must also be inited already. | |
1349 | |
1350 | |
1351 4. Decoding | |
1352 ----------- | |
1353 | |
1354 Decoding converts a PNG compressed image to a raw pixel buffer. | |
1355 | |
1356 Most documentation on using the decoder is at its declarations in the header | |
1357 above. For C, simple decoding can be done with functions such as | |
1358 lodepng_decode32, and more advanced decoding can be done with the struct | |
1359 LodePNGState and lodepng_decode. For C++, all decoding can be done with the | |
1360 various lodepng::decode functions, and lodepng::State can be used for advanced | |
1361 features. | |
1362 | |
1363 When using the LodePNGState, it uses the following fields for decoding: | |
1364 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here | |
1365 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get | |
1366 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use | |
1367 | |
1368 LodePNGInfo info_png | |
1369 -------------------- | |
1370 | |
1371 After decoding, this contains extra information of the PNG image, except the actual | |
1372 pixels, width and height because these are already gotten directly from the decoder | |
1373 functions. | |
1374 | |
1375 It contains for example the original color type of the PNG image, text comments, | |
1376 suggested background color, etc... More details about the LodePNGInfo struct are | |
1377 at its declaration documentation. | |
1378 | |
1379 LodePNGColorMode info_raw | |
1380 ------------------------- | |
1381 | |
1382 When decoding, here you can specify which color type you want | |
1383 the resulting raw image to be. If this is different from the colortype of the | |
1384 PNG, then the decoder will automatically convert the result. This conversion | |
1385 always works, except if you want it to convert a color PNG to grayscale or to | |
1386 a palette with missing colors. | |
1387 | |
1388 By default, 32-bit color is used for the result. | |
1389 | |
1390 LodePNGDecoderSettings decoder | |
1391 ------------------------------ | |
1392 | |
1393 The settings can be used to ignore the errors created by invalid CRC and Adler32 | |
1394 chunks, and to disable the decoding of tEXt chunks. | |
1395 | |
1396 There's also a setting color_convert, true by default. If false, no conversion | |
1397 is done, the resulting data will be as it was in the PNG (after decompression) | |
1398 and you'll have to puzzle the colors of the pixels together yourself using the | |
1399 color type information in the LodePNGInfo. | |
1400 | |
1401 | |
1402 5. Encoding | |
1403 ----------- | |
1404 | |
1405 Encoding converts a raw pixel buffer to a PNG compressed image. | |
1406 | |
1407 Most documentation on using the encoder is at its declarations in the header | |
1408 above. For C, simple encoding can be done with functions such as | |
1409 lodepng_encode32, and more advanced decoding can be done with the struct | |
1410 LodePNGState and lodepng_encode. For C++, all encoding can be done with the | |
1411 various lodepng::encode functions, and lodepng::State can be used for advanced | |
1412 features. | |
1413 | |
1414 Like the decoder, the encoder can also give errors. However it gives less errors | |
1415 since the encoder input is trusted, the decoder input (a PNG image that could | |
1416 be forged by anyone) is not trusted. | |
1417 | |
1418 When using the LodePNGState, it uses the following fields for encoding: | |
1419 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be. | |
1420 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has | |
1421 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use | |
1422 | |
1423 LodePNGInfo info_png | |
1424 -------------------- | |
1425 | |
1426 When encoding, you use this the opposite way as when decoding: for encoding, | |
1427 you fill in the values you want the PNG to have before encoding. By default it's | |
1428 not needed to specify a color type for the PNG since it's automatically chosen, | |
1429 but it's possible to choose it yourself given the right settings. | |
1430 | |
1431 The encoder will not always exactly match the LodePNGInfo struct you give, | |
1432 it tries as close as possible. Some things are ignored by the encoder. The | |
1433 encoder uses, for example, the following settings from it when applicable: | |
1434 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the | |
1435 background color, the interlace method, unknown chunks, ... | |
1436 | |
1437 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk. | |
1438 If the palette contains any colors for which the alpha channel is not 255 (so | |
1439 there are translucent colors in the palette), it'll add a tRNS chunk. | |
1440 | |
1441 LodePNGColorMode info_raw | |
1442 ------------------------- | |
1443 | |
1444 You specify the color type of the raw image that you give to the input here, | |
1445 including a possible transparent color key and palette you happen to be using in | |
1446 your raw image data. | |
1447 | |
1448 By default, 32-bit color is assumed, meaning your input has to be in RGBA | |
1449 format with 4 bytes (unsigned chars) per pixel. | |
1450 | |
1451 LodePNGEncoderSettings encoder | |
1452 ------------------------------ | |
1453 | |
1454 The following settings are supported (some are in sub-structs): | |
1455 *) auto_convert: when this option is enabled, the encoder will | |
1456 automatically choose the smallest possible color mode (including color key) that | |
1457 can encode the colors of all pixels without information loss. | |
1458 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree, | |
1459 2 = dynamic huffman tree (best compression). Should be 2 for proper | |
1460 compression. | |
1461 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be | |
1462 true for proper compression. | |
1463 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value | |
1464 2048 by default, but can be set to 32768 for better, but slow, compression. | |
1465 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE | |
1466 chunk if force_palette is true. This can used as suggested palette to convert | |
1467 to by viewers that don't support more than 256 colors (if those still exist) | |
1468 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image. | |
1469 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks. | |
1470 zTXt chunks use zlib compression on the text. This gives a smaller result on | |
1471 large texts but a larger result on small texts (such as a single program name). | |
1472 It's all tEXt or all zTXt though, there's no separate setting per text yet. | |
1473 | |
1474 | |
1475 6. color conversions | |
1476 -------------------- | |
1477 | |
1478 An important thing to note about LodePNG, is that the color type of the PNG, and | |
1479 the color type of the raw image, are completely independent. By default, when | |
1480 you decode a PNG, you get the result as a raw image in the color type you want, | |
1481 no matter whether the PNG was encoded with a palette, grayscale or RGBA color. | |
1482 And if you encode an image, by default LodePNG will automatically choose the PNG | |
1483 color type that gives good compression based on the values of colors and amount | |
1484 of colors in the image. It can be configured to let you control it instead as | |
1485 well, though. | |
1486 | |
1487 To be able to do this, LodePNG does conversions from one color mode to another. | |
1488 It can convert from almost any color type to any other color type, except the | |
1489 following conversions: RGB to grayscale is not supported, and converting to a | |
1490 palette when the palette doesn't have a required color is not supported. This is | |
1491 not supported on purpose: this is information loss which requires a color | |
1492 reduction algorithm that is beyond the scope of a PNG encoder (yes, RGB to gray | |
1493 is easy, but there are multiple ways if you want to give some channels more | |
1494 weight). | |
1495 | |
1496 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB | |
1497 color, no matter what color type the PNG has. And by default when encoding, | |
1498 LodePNG automatically picks the best color model for the output PNG, and expects | |
1499 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control | |
1500 the color format of the images yourself, you can skip this chapter. | |
1501 | |
1502 6.1. PNG color types | |
1503 -------------------- | |
1504 | |
1505 A PNG image can have many color types, ranging from 1-bit color to 64-bit color, | |
1506 as well as palettized color modes. After the zlib decompression and unfiltering | |
1507 in the PNG image is done, the raw pixel data will have that color type and thus | |
1508 a certain amount of bits per pixel. If you want the output raw image after | |
1509 decoding to have another color type, a conversion is done by LodePNG. | |
1510 | |
1511 The PNG specification gives the following color types: | |
1512 | |
1513 0: grayscale, bit depths 1, 2, 4, 8, 16 | |
1514 2: RGB, bit depths 8 and 16 | |
1515 3: palette, bit depths 1, 2, 4 and 8 | |
1516 4: grayscale with alpha, bit depths 8 and 16 | |
1517 6: RGBA, bit depths 8 and 16 | |
1518 | |
1519 Bit depth is the amount of bits per pixel per color channel. So the total amount | |
1520 of bits per pixel is: amount of channels * bitdepth. | |
1521 | |
1522 6.2. color conversions | |
1523 ---------------------- | |
1524 | |
1525 As explained in the sections about the encoder and decoder, you can specify | |
1526 color types and bit depths in info_png and info_raw to change the default | |
1527 behaviour. | |
1528 | |
1529 If, when decoding, you want the raw image to be something else than the default, | |
1530 you need to set the color type and bit depth you want in the LodePNGColorMode, | |
1531 or the parameters colortype and bitdepth of the simple decoding function. | |
1532 | |
1533 If, when encoding, you use another color type than the default in the raw input | |
1534 image, you need to specify its color type and bit depth in the LodePNGColorMode | |
1535 of the raw image, or use the parameters colortype and bitdepth of the simple | |
1536 encoding function. | |
1537 | |
1538 If, when encoding, you don't want LodePNG to choose the output PNG color type | |
1539 but control it yourself, you need to set auto_convert in the encoder settings | |
1540 to false, and specify the color type you want in the LodePNGInfo of the | |
1541 encoder (including palette: it can generate a palette if auto_convert is true, | |
1542 otherwise not). | |
1543 | |
1544 If the input and output color type differ (whether user chosen or auto chosen), | |
1545 LodePNG will do a color conversion, which follows the rules below, and may | |
1546 sometimes result in an error. | |
1547 | |
1548 To avoid some confusion: | |
1549 -the decoder converts from PNG to raw image | |
1550 -the encoder converts from raw image to PNG | |
1551 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image | |
1552 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG | |
1553 -when encoding, the color type in LodePNGInfo is ignored if auto_convert | |
1554 is enabled, it is automatically generated instead | |
1555 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original | |
1556 PNG image, but it can be ignored since the raw image has the color type you requested instead | |
1557 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion | |
1558 between the color types is done if the color types are supported. If it is not | |
1559 supported, an error is returned. If the types are the same, no conversion is done. | |
1560 -even though some conversions aren't supported, LodePNG supports loading PNGs from any | |
1561 colortype and saving PNGs to any colortype, sometimes it just requires preparing | |
1562 the raw image correctly before encoding. | |
1563 -both encoder and decoder use the same color converter. | |
1564 | |
1565 The function lodepng_convert does the color conversion. It is available in the | |
1566 interface but normally isn't needed since the encoder and decoder already call | |
1567 it. | |
1568 | |
1569 Non supported color conversions: | |
1570 -color to grayscale when non-gray pixels are present: no error is thrown, but | |
1571 the result will look ugly because only the red channel is taken (it assumes all | |
1572 three channels are the same in this case so ignores green and blue). The reason | |
1573 no error is given is to allow converting from three-channel grayscale images to | |
1574 one-channel even if there are numerical imprecisions. | |
1575 -anything to palette when the palette does not have an exact match for a from-color | |
1576 in it: in this case an error is thrown | |
1577 | |
1578 Supported color conversions: | |
1579 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA | |
1580 -any gray or gray+alpha, to gray or gray+alpha | |
1581 -anything to a palette, as long as the palette has the requested colors in it | |
1582 -removing alpha channel | |
1583 -higher to smaller bitdepth, and vice versa | |
1584 | |
1585 If you want no color conversion to be done (e.g. for speed or control): | |
1586 -In the encoder, you can make it save a PNG with any color type by giving the | |
1587 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to | |
1588 false. | |
1589 -In the decoder, you can make it store the pixel data in the same color type | |
1590 as the PNG has, by setting the color_convert setting to false. Settings in | |
1591 info_raw are then ignored. | |
1592 | |
1593 6.3. padding bits | |
1594 ----------------- | |
1595 | |
1596 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines | |
1597 have a bit amount that isn't a multiple of 8, then padding bits are used so that each | |
1598 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output. | |
1599 The raw input image you give to the encoder, and the raw output image you get from the decoder | |
1600 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width | |
1601 of 7 pixels, the first pixel of the second scanline will the 8th bit of the first byte, | |
1602 not the first bit of a new byte. | |
1603 | |
1604 6.4. A note about 16-bits per channel and endianness | |
1605 ---------------------------------------------------- | |
1606 | |
1607 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like | |
1608 for any other color format. The 16-bit values are stored in big endian (most | |
1609 significant byte first) in these arrays. This is the opposite order of the | |
1610 little endian used by x86 CPU's. | |
1611 | |
1612 LodePNG always uses big endian because the PNG file format does so internally. | |
1613 Conversions to other formats than PNG uses internally are not supported by | |
1614 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit | |
1615 colors, the order in which you store R, G, B and A, and so on. Supporting and | |
1616 converting to/from all that is outside the scope of LodePNG. | |
1617 | |
1618 This may mean that, depending on your use case, you may want to convert the big | |
1619 endian output of LodePNG to little endian with a for loop. This is certainly not | |
1620 always needed, many applications and libraries support big endian 16-bit colors | |
1621 anyway, but it means you cannot simply cast the unsigned char* buffer to an | |
1622 unsigned short* buffer on x86 CPUs. | |
1623 | |
1624 | |
1625 7. error values | |
1626 --------------- | |
1627 | |
1628 All functions in LodePNG that return an error code, return 0 if everything went | |
1629 OK, or a non-zero code if there was an error. | |
1630 | |
1631 The meaning of the LodePNG error values can be retrieved with the function | |
1632 lodepng_error_text: given the numerical error code, it returns a description | |
1633 of the error in English as a string. | |
1634 | |
1635 Check the implementation of lodepng_error_text to see the meaning of each code. | |
1636 | |
1637 It is not recommended to use the numerical values to programmatically make | |
1638 different decisions based on error types as the numbers are not guaranteed to | |
1639 stay backwards compatible. They are for human consumption only. Programmatically | |
1640 only 0 or non-0 matter. | |
1641 | |
1642 | |
1643 8. chunks and PNG editing | |
1644 ------------------------- | |
1645 | |
1646 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG | |
1647 editor that should follow the rules about handling of unknown chunks, or if your | |
1648 program is able to read other types of chunks than the ones handled by LodePNG, | |
1649 then that's possible with the chunk functions of LodePNG. | |
1650 | |
1651 A PNG chunk has the following layout: | |
1652 | |
1653 4 bytes length | |
1654 4 bytes type name | |
1655 length bytes data | |
1656 4 bytes CRC | |
1657 | |
1658 8.1. iterating through chunks | |
1659 ----------------------------- | |
1660 | |
1661 If you have a buffer containing the PNG image data, then the first chunk (the | |
1662 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the | |
1663 signature of the PNG and are not part of a chunk. But if you start at byte 8 | |
1664 then you have a chunk, and can check the following things of it. | |
1665 | |
1666 NOTE: none of these functions check for memory buffer boundaries. To avoid | |
1667 exploits, always make sure the buffer contains all the data of the chunks. | |
1668 When using lodepng_chunk_next, make sure the returned value is within the | |
1669 allocated memory. | |
1670 | |
1671 unsigned lodepng_chunk_length(const unsigned char* chunk): | |
1672 | |
1673 Get the length of the chunk's data. The total chunk length is this length + 12. | |
1674 | |
1675 void lodepng_chunk_type(char type[5], const unsigned char* chunk): | |
1676 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type): | |
1677 | |
1678 Get the type of the chunk or compare if it's a certain type | |
1679 | |
1680 unsigned char lodepng_chunk_critical(const unsigned char* chunk): | |
1681 unsigned char lodepng_chunk_private(const unsigned char* chunk): | |
1682 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk): | |
1683 | |
1684 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are). | |
1685 Check if the chunk is private (public chunks are part of the standard, private ones not). | |
1686 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical | |
1687 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your | |
1688 program doesn't handle that type of unknown chunk. | |
1689 | |
1690 unsigned char* lodepng_chunk_data(unsigned char* chunk): | |
1691 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk): | |
1692 | |
1693 Get a pointer to the start of the data of the chunk. | |
1694 | |
1695 unsigned lodepng_chunk_check_crc(const unsigned char* chunk): | |
1696 void lodepng_chunk_generate_crc(unsigned char* chunk): | |
1697 | |
1698 Check if the crc is correct or generate a correct one. | |
1699 | |
1700 unsigned char* lodepng_chunk_next(unsigned char* chunk): | |
1701 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk): | |
1702 | |
1703 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these | |
1704 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough | |
1705 data available in the buffer to be able to go to the next chunk. | |
1706 | |
1707 unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk): | |
1708 unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length, | |
1709 const char* type, const unsigned char* data): | |
1710 | |
1711 These functions are used to create new chunks that are appended to the data in *out that has | |
1712 length *outsize. The append function appends an existing chunk to the new data. The create | |
1713 function creates a new chunk with the given parameters and appends it. Type is the 4-letter | |
1714 name of the chunk. | |
1715 | |
1716 8.2. chunks in info_png | |
1717 ----------------------- | |
1718 | |
1719 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3 | |
1720 buffers (each with size) to contain 3 types of unknown chunks: | |
1721 the ones that come before the PLTE chunk, the ones that come between the PLTE | |
1722 and the IDAT chunks, and the ones that come after the IDAT chunks. | |
1723 It's necessary to make the distinction between these 3 cases because the PNG | |
1724 standard forces to keep the ordering of unknown chunks compared to the critical | |
1725 chunks, but does not force any other ordering rules. | |
1726 | |
1727 info_png.unknown_chunks_data[0] is the chunks before PLTE | |
1728 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT | |
1729 info_png.unknown_chunks_data[2] is the chunks after IDAT | |
1730 | |
1731 The chunks in these 3 buffers can be iterated through and read by using the same | |
1732 way described in the previous subchapter. | |
1733 | |
1734 When using the decoder to decode a PNG, you can make it store all unknown chunks | |
1735 if you set the option settings.remember_unknown_chunks to 1. By default, this | |
1736 option is off (0). | |
1737 | |
1738 The encoder will always encode unknown chunks that are stored in the info_png. | |
1739 If you need it to add a particular chunk that isn't known by LodePNG, you can | |
1740 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in | |
1741 info_png.unknown_chunks_data[x]. | |
1742 | |
1743 Chunks that are known by LodePNG should not be added in that way. E.g. to make | |
1744 LodePNG add a bKGD chunk, set background_defined to true and add the correct | |
1745 parameters there instead. | |
1746 | |
1747 | |
1748 9. compiler support | |
1749 ------------------- | |
1750 | |
1751 No libraries other than the current standard C library are needed to compile | |
1752 LodePNG. For the C++ version, only the standard C++ library is needed on top. | |
1753 Add the files lodepng.c(pp) and lodepng.h to your project, include | |
1754 lodepng.h where needed, and your program can read/write PNG files. | |
1755 | |
1756 It is compatible with C90 and up, and C++03 and up. | |
1757 | |
1758 If performance is important, use optimization when compiling! For both the | |
1759 encoder and decoder, this makes a large difference. | |
1760 | |
1761 Make sure that LodePNG is compiled with the same compiler of the same version | |
1762 and with the same settings as the rest of the program, or the interfaces with | |
1763 std::vectors and std::strings in C++ can be incompatible. | |
1764 | |
1765 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets. | |
1766 | |
1767 *) gcc and g++ | |
1768 | |
1769 LodePNG is developed in gcc so this compiler is natively supported. It gives no | |
1770 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++ | |
1771 version 4.7.1 on Linux, 32-bit and 64-bit. | |
1772 | |
1773 *) Clang | |
1774 | |
1775 Fully supported and warning-free. | |
1776 | |
1777 *) Mingw | |
1778 | |
1779 The Mingw compiler (a port of gcc for Windows) should be fully supported by | |
1780 LodePNG. | |
1781 | |
1782 *) Visual Studio and Visual C++ Express Edition | |
1783 | |
1784 LodePNG should be warning-free with warning level W4. Two warnings were disabled | |
1785 with pragmas though: warning 4244 about implicit conversions, and warning 4996 | |
1786 where it wants to use a non-standard function fopen_s instead of the standard C | |
1787 fopen. | |
1788 | |
1789 Visual Studio may want "stdafx.h" files to be included in each source file and | |
1790 give an error "unexpected end of file while looking for precompiled header". | |
1791 This is not standard C++ and will not be added to the stock LodePNG. You can | |
1792 disable it for lodepng.cpp only by right clicking it, Properties, C/C++, | |
1793 Precompiled Headers, and set it to Not Using Precompiled Headers there. | |
1794 | |
1795 NOTE: Modern versions of VS should be fully supported, but old versions, e.g. | |
1796 VS6, are not guaranteed to work. | |
1797 | |
1798 *) Compilers on Macintosh | |
1799 | |
1800 LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for | |
1801 C and C++. | |
1802 | |
1803 *) Other Compilers | |
1804 | |
1805 If you encounter problems on any compilers, feel free to let me know and I may | |
1806 try to fix it if the compiler is modern and standards compliant. | |
1807 | |
1808 | |
1809 10. examples | |
1810 ------------ | |
1811 | |
1812 This decoder example shows the most basic usage of LodePNG. More complex | |
1813 examples can be found on the LodePNG website. | |
1814 | |
1815 NOTE: these examples do not support wide-character filenames, you can use an | |
1816 external method to handle such files and encode or decode in-memory | |
1817 | |
1818 10.1. decoder C++ example | |
1819 ------------------------- | |
1820 | |
1821 #include "lodepng.h" | |
1822 #include <iostream> | |
1823 | |
1824 int main(int argc, char *argv[]) { | |
1825 const char* filename = argc > 1 ? argv[1] : "test.png"; | |
1826 | |
1827 //load and decode | |
1828 std::vector<unsigned char> image; | |
1829 unsigned width, height; | |
1830 unsigned error = lodepng::decode(image, width, height, filename); | |
1831 | |
1832 //if there's an error, display it | |
1833 if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl; | |
1834 | |
1835 //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ... | |
1836 } | |
1837 | |
1838 10.2. decoder C example | |
1839 ----------------------- | |
1840 | |
1841 #include "lodepng.h" | |
1842 | |
1843 int main(int argc, char *argv[]) { | |
1844 unsigned error; | |
1845 unsigned char* image; | |
1846 size_t width, height; | |
1847 const char* filename = argc > 1 ? argv[1] : "test.png"; | |
1848 | |
1849 error = lodepng_decode32_file(&image, &width, &height, filename); | |
1850 | |
1851 if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error)); | |
1852 | |
1853 / * use image here * / | |
1854 | |
1855 free(image); | |
1856 return 0; | |
1857 } | |
1858 | |
1859 11. state settings reference | |
1860 ---------------------------- | |
1861 | |
1862 A quick reference of some settings to set on the LodePNGState | |
1863 | |
1864 For decoding: | |
1865 | |
1866 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums | |
1867 state.decoder.zlibsettings.custom_...: use custom inflate function | |
1868 state.decoder.ignore_crc: ignore CRC checksums | |
1869 state.decoder.ignore_critical: ignore unknown critical chunks | |
1870 state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors | |
1871 state.decoder.color_convert: convert internal PNG color to chosen one | |
1872 state.decoder.read_text_chunks: whether to read in text metadata chunks | |
1873 state.decoder.remember_unknown_chunks: whether to read in unknown chunks | |
1874 state.info_raw.colortype: desired color type for decoded image | |
1875 state.info_raw.bitdepth: desired bit depth for decoded image | |
1876 state.info_raw....: more color settings, see struct LodePNGColorMode | |
1877 state.info_png....: no settings for decoder but ouput, see struct LodePNGInfo | |
1878 | |
1879 For encoding: | |
1880 | |
1881 state.encoder.zlibsettings.btype: disable compression by setting it to 0 | |
1882 state.encoder.zlibsettings.use_lz77: use LZ77 in compression | |
1883 state.encoder.zlibsettings.windowsize: tweak LZ77 windowsize | |
1884 state.encoder.zlibsettings.minmatch: tweak min LZ77 length to match | |
1885 state.encoder.zlibsettings.nicematch: tweak LZ77 match where to stop searching | |
1886 state.encoder.zlibsettings.lazymatching: try one more LZ77 matching | |
1887 state.encoder.zlibsettings.custom_...: use custom deflate function | |
1888 state.encoder.auto_convert: choose optimal PNG color type, if 0 uses info_png | |
1889 state.encoder.filter_palette_zero: PNG filter strategy for palette | |
1890 state.encoder.filter_strategy: PNG filter strategy to encode with | |
1891 state.encoder.force_palette: add palette even if not encoding to one | |
1892 state.encoder.add_id: add LodePNG identifier and version as a text chunk | |
1893 state.encoder.text_compression: use compressed text chunks for metadata | |
1894 state.info_raw.colortype: color type of raw input image you provide | |
1895 state.info_raw.bitdepth: bit depth of raw input image you provide | |
1896 state.info_raw: more color settings, see struct LodePNGColorMode | |
1897 state.info_png.color.colortype: desired color type if auto_convert is false | |
1898 state.info_png.color.bitdepth: desired bit depth if auto_convert is false | |
1899 state.info_png.color....: more color settings, see struct LodePNGColorMode | |
1900 state.info_png....: more PNG related settings, see struct LodePNGInfo | |
1901 | |
1902 | |
1903 12. changes | |
1904 ----------- | |
1905 | |
1906 The version number of LodePNG is the date of the change given in the format | |
1907 yyyymmdd. | |
1908 | |
1909 Some changes aren't backwards compatible. Those are indicated with a (!) | |
1910 symbol. | |
1911 | |
1912 Not all changes are listed here, the commit history in github lists more: | |
1913 https://github.com/lvandeve/lodepng | |
1914 | |
1915 *) 10 apr 2023: faster CRC32 implementation, but with larger lookup table. | |
1916 *) 13 jun 2022: added support for the sBIT chunk. | |
1917 *) 09 jan 2022: minor decoder speed improvements. | |
1918 *) 27 jun 2021: added warnings that file reading/writing functions don't support | |
1919 wide-character filenames (support for this is not planned, opening files is | |
1920 not the core part of PNG decoding/decoding and is platform dependent). | |
1921 *) 17 okt 2020: prevent decoding too large text/icc chunks by default. | |
1922 *) 06 mar 2020: simplified some of the dynamic memory allocations. | |
1923 *) 12 jan 2020: (!) added 'end' argument to lodepng_chunk_next to allow correct | |
1924 overflow checks. | |
1925 *) 14 aug 2019: around 25% faster decoding thanks to huffman lookup tables. | |
1926 *) 15 jun 2019: (!) auto_choose_color API changed (for bugfix: don't use palette | |
1927 if gray ICC profile) and non-ICC LodePNGColorProfile renamed to | |
1928 LodePNGColorStats. | |
1929 *) 30 dec 2018: code style changes only: removed newlines before opening braces. | |
1930 *) 10 sep 2018: added way to inspect metadata chunks without full decoding. | |
1931 *) 19 aug 2018: (!) fixed color mode bKGD is encoded with and made it use | |
1932 palette index in case of palette. | |
1933 *) 10 aug 2018: (!) added support for gAMA, cHRM, sRGB and iCCP chunks. This | |
1934 change is backwards compatible unless you relied on unknown_chunks for those. | |
1935 *) 11 jun 2018: less restrictive check for pixel size integer overflow | |
1936 *) 14 jan 2018: allow optionally ignoring a few more recoverable errors | |
1937 *) 17 sep 2017: fix memory leak for some encoder input error cases | |
1938 *) 27 nov 2016: grey+alpha auto color model detection bugfix | |
1939 *) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort). | |
1940 *) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within | |
1941 the limits of pure C90). | |
1942 *) 08 dec 2015: Made load_file function return error if file can't be opened. | |
1943 *) 24 okt 2015: Bugfix with decoding to palette output. | |
1944 *) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding. | |
1945 *) 24 aug 2014: Moved to github | |
1946 *) 23 aug 2014: Reduced needless memory usage of decoder. | |
1947 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for | |
1948 simplicity. Made ColorProfile public. | |
1949 *) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization. | |
1950 *) 22 dec 2013: Power of two windowsize required for optimization. | |
1951 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key. | |
1952 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png). | |
1953 *) 11 mar 2013: (!) Bugfix with custom free. Changed from "my" to "lodepng_" | |
1954 prefix for the custom allocators and made it possible with a new #define to | |
1955 use custom ones in your project without needing to change lodepng's code. | |
1956 *) 28 jan 2013: Bugfix with color key. | |
1957 *) 27 okt 2012: Tweaks in text chunk keyword length error handling. | |
1958 *) 8 okt 2012: (!) Added new filter strategy (entropy) and new auto color mode. | |
1959 (no palette). Better deflate tree encoding. New compression tweak settings. | |
1960 Faster color conversions while decoding. Some internal cleanups. | |
1961 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit. | |
1962 *) 1 sep 2012: (!) Removed #define's for giving custom (de)compression functions | |
1963 and made it work with function pointers instead. | |
1964 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc | |
1965 and free functions and toggle #defines from compiler flags. Small fixes. | |
1966 *) 6 may 2012: (!) Made plugging in custom zlib/deflate functions more flexible. | |
1967 *) 22 apr 2012: (!) Made interface more consistent, renaming a lot. Removed | |
1968 redundant C++ codec classes. Reduced amount of structs. Everything changed, | |
1969 but it is cleaner now imho and functionality remains the same. Also fixed | |
1970 several bugs and shrunk the implementation code. Made new samples. | |
1971 *) 6 nov 2011: (!) By default, the encoder now automatically chooses the best | |
1972 PNG color model and bit depth, based on the amount and type of colors of the | |
1973 raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color. | |
1974 *) 9 okt 2011: simpler hash chain implementation for the encoder. | |
1975 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching. | |
1976 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking. | |
1977 A bug with the PNG filtertype heuristic was fixed, so that it chooses much | |
1978 better ones (it's quite significant). A setting to do an experimental, slow, | |
1979 brute force search for PNG filter types is added. | |
1980 *) 17 aug 2011: (!) changed some C zlib related function names. | |
1981 *) 16 aug 2011: made the code less wide (max 120 characters per line). | |
1982 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors. | |
1983 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled. | |
1984 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman | |
1985 to optimize long sequences of zeros. | |
1986 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and | |
1987 LodePNG_InfoColor_canHaveAlpha functions for convenience. | |
1988 *) 7 nov 2010: added LodePNG_error_text function to get error code description. | |
1989 *) 30 okt 2010: made decoding slightly faster | |
1990 *) 26 okt 2010: (!) changed some C function and struct names (more consistent). | |
1991 Reorganized the documentation and the declaration order in the header. | |
1992 *) 08 aug 2010: only changed some comments and external samples. | |
1993 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version. | |
1994 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers. | |
1995 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could | |
1996 read by ignoring the problem but windows apps couldn't. | |
1997 *) 06 jun 2008: added more error checks for out of memory cases. | |
1998 *) 26 apr 2008: added a few more checks here and there to ensure more safety. | |
1999 *) 06 mar 2008: crash with encoding of strings fixed | |
2000 *) 02 feb 2008: support for international text chunks added (iTXt) | |
2001 *) 23 jan 2008: small cleanups, and #defines to divide code in sections | |
2002 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor. | |
2003 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder. | |
2004 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added | |
2005 Also various fixes, such as in the deflate and the padding bits code. | |
2006 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved | |
2007 filtering code of encoder. | |
2008 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A | |
2009 C++ wrapper around this provides an interface almost identical to before. | |
2010 Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code | |
2011 are together in these files but it works both for C and C++ compilers. | |
2012 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks | |
2013 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible | |
2014 *) 09 aug 2007: some VS2005 warnings removed again | |
2015 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code | |
2016 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images | |
2017 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing | |
2018 invalid std::vector element [0] fixed, and level 3 and 4 warnings removed | |
2019 *) 02 jun 2007: made the encoder add a tag with version by default | |
2020 *) 27 may 2007: zlib and png code separated (but still in the same file), | |
2021 simple encoder/decoder functions added for more simple usage cases | |
2022 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69), | |
2023 moved some examples from here to lodepng_examples.cpp | |
2024 *) 12 may 2007: palette decoding bug fixed | |
2025 *) 24 apr 2007: changed the license from BSD to the zlib license | |
2026 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks. | |
2027 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding | |
2028 palettized PNG images. Plus little interface change with palette and texts. | |
2029 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes. | |
2030 Fixed a bug where the end code of a block had length 0 in the Huffman tree. | |
2031 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented | |
2032 and supported by the encoder, resulting in smaller PNGs at the output. | |
2033 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone. | |
2034 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any | |
2035 greyscale type to 8-bit greyscale with or without alpha. | |
2036 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types | |
2037 to convert to and is more uniform. See the manual for how it works now. | |
2038 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days: | |
2039 encode/decode custom tEXt chunks, separate classes for zlib & deflate, and | |
2040 at last made the decoder give errors for incorrect Adler32 or Crc. | |
2041 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel. | |
2042 *) 29 dec 2006: Added support for encoding images without alpha channel, and | |
2043 cleaned out code as well as making certain parts faster. | |
2044 *) 28 dec 2006: Added "Settings" to the encoder. | |
2045 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now. | |
2046 Removed some code duplication in the decoder. Fixed little bug in an example. | |
2047 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter. | |
2048 Fixed a bug of the decoder with 16-bit per color. | |
2049 *) 15 okt 2006: Changed documentation structure | |
2050 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the | |
2051 given image buffer, however for now it's not compressed. | |
2052 *) 08 sep 2006: (!) Changed to interface with a Decoder class | |
2053 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different | |
2054 way. Renamed decodePNG to decodePNGGeneric. | |
2055 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a | |
2056 struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy. | |
2057 *) 28 jul 2006: Cleaned the code and added new error checks. | |
2058 Corrected terminology "deflate" into "inflate". | |
2059 *) 23 jun 2006: Added SDL example in the documentation in the header, this | |
2060 example allows easy debugging by displaying the PNG and its transparency. | |
2061 *) 22 jun 2006: (!) Changed way to obtain error value. Added | |
2062 loadFile function for convenience. Made decodePNG32 faster. | |
2063 *) 21 jun 2006: (!) Changed type of info vector to unsigned. | |
2064 Changed position of palette in info vector. Fixed an important bug that | |
2065 happened on PNGs with an uncompressed block. | |
2066 *) 16 jun 2006: Internally changed unsigned into unsigned where | |
2067 needed, and performed some optimizations. | |
2068 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them | |
2069 in LodePNG namespace. Changed the order of the parameters. Rewrote the | |
2070 documentation in the header. Renamed files to lodepng.cpp and lodepng.h | |
2071 *) 22 apr 2006: Optimized and improved some code | |
2072 *) 07 sep 2005: (!) Changed to std::vector interface | |
2073 *) 12 aug 2005: Initial release (C++, decoder only) | |
2074 | |
2075 | |
2076 13. contact information | |
2077 ----------------------- | |
2078 | |
2079 Feel free to contact me with suggestions, problems, comments, ... concerning | |
2080 LodePNG. If you encounter a PNG image that doesn't work properly with this | |
2081 decoder, feel free to send it and I'll use it to find and fix the problem. | |
2082 | |
2083 My email address is (puzzle the account and domain together with an @ symbol): | |
2084 Domain: gmail dot com. | |
2085 Account: lode dot vandevenne. | |
2086 | |
2087 | |
2088 Copyright (c) 2005-2022 Lode Vandevenne | |
2089 */ |