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lodepng.h
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1 /*
2 LodePNG version 20180114
3 
4 Copyright (c) 2005-2018 Lode Vandevenne
5 
6 This software is provided 'as-is', without any express or implied
7 warranty. In no event will the authors be held liable for any damages
8 arising from the use of this software.
9 
10 Permission is granted to anyone to use this software for any purpose,
11 including commercial applications, and to alter it and redistribute it
12 freely, subject to the following restrictions:
13 
14  1. The origin of this software must not be misrepresented; you must not
15  claim that you wrote the original software. If you use this software
16  in a product, an acknowledgment in the product documentation would be
17  appreciated but is not required.
18 
19  2. Altered source versions must be plainly marked as such, and must not be
20  misrepresented as being the original software.
21 
22  3. This notice may not be removed or altered from any source
23  distribution.
24 */
25 
26 #ifndef LODEPNG_H
27 #define LODEPNG_H
28 
29 #include <string.h> /*for size_t*/
30 
31 // ** WK **
32 #define LODEPNG_COMPILE_DECODER
33 #define LODEPNG_COMPILE_PNG
34 #define LODEPNG_COMPILE_DISK
35 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS
36 
37 extern const char* LODEPNG_VERSION_STRING;
38 
39 /*
40 The following #defines are used to create code sections. They can be disabled
41 to disable code sections, which can give faster compile time and smaller binary.
42 The "NO_COMPILE" defines are designed to be used to pass as defines to the
43 compiler command to disable them without modifying this header, e.g.
44 -DLODEPNG_NO_COMPILE_ZLIB for gcc.
45 In addition to those below, you can also define LODEPNG_NO_COMPILE_CRC to
46 allow implementing a custom lodepng_crc32.
47 */
48 /*deflate & zlib. If disabled, you must specify alternative zlib functions in
49 the custom_zlib field of the compress and decompress settings*/
50 #ifndef LODEPNG_NO_COMPILE_ZLIB
51 #define LODEPNG_COMPILE_ZLIB
52 #endif
53 /*png encoder and png decoder*/
54 #ifndef LODEPNG_NO_COMPILE_PNG
55 #define LODEPNG_COMPILE_PNG
56 #endif
57 /*deflate&zlib decoder and png decoder*/
58 #ifndef LODEPNG_NO_COMPILE_DECODER
59 #define LODEPNG_COMPILE_DECODER
60 #endif
61 /*deflate&zlib encoder and png encoder*/
62 #ifndef LODEPNG_NO_COMPILE_ENCODER
63 #define LODEPNG_COMPILE_ENCODER
64 #endif
65 /*the optional built in harddisk file loading and saving functions*/
66 #ifndef LODEPNG_NO_COMPILE_DISK
67 #define LODEPNG_COMPILE_DISK
68 #endif
69 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/
70 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS
71 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS
72 #endif
73 /*ability to convert error numerical codes to English text string*/
74 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT
75 #define LODEPNG_COMPILE_ERROR_TEXT
76 #endif
77 /*Compile the default allocators (C's free, malloc and realloc). If you disable this,
78 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your
79 source files with custom allocators.*/
80 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS
81 #define LODEPNG_COMPILE_ALLOCATORS
82 #endif
83 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/
84 #ifdef __cplusplus
85 #ifndef LODEPNG_NO_COMPILE_CPP
86 #define LODEPNG_COMPILE_CPP
87 #endif
88 #endif
89 
90 #ifdef LODEPNG_COMPILE_CPP
91 #include <vector>
92 #include <string>
93 #endif /*LODEPNG_COMPILE_CPP*/
94 
95 #ifdef LODEPNG_COMPILE_PNG
96 /*The PNG color types (also used for raw).*/
97 typedef enum LodePNGColorType
98 {
99  LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/
100  LCT_RGB = 2, /*RGB: 8,16 bit*/
101  LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/
102  LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/
103  LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/
105 
106 #ifdef LODEPNG_COMPILE_DECODER
107 /*
108 Converts PNG data in memory to raw pixel data.
109 out: Output parameter. Pointer to buffer that will contain the raw pixel data.
110  After decoding, its size is w * h * (bytes per pixel) bytes larger than
111  initially. Bytes per pixel depends on colortype and bitdepth.
112  Must be freed after usage with free(*out).
113  Note: for 16-bit per channel colors, uses big endian format like PNG does.
114 w: Output parameter. Pointer to width of pixel data.
115 h: Output parameter. Pointer to height of pixel data.
116 in: Memory buffer with the PNG file.
117 insize: size of the in buffer.
118 colortype: the desired color type for the raw output image. See explanation on PNG color types.
119 bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types.
120 Return value: LodePNG error code (0 means no error).
121 */
122 unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h,
123  const unsigned char* in, size_t insize,
124  LodePNGColorType colortype, unsigned bitdepth);
125 
126 /*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/
127 unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h,
128  const unsigned char* in, size_t insize);
129 
130 /*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/
131 unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h,
132  const unsigned char* in, size_t insize);
133 
134 #ifdef LODEPNG_COMPILE_DISK
135 /*
136 Load PNG from disk, from file with given name.
137 Same as the other decode functions, but instead takes a filename as input.
138 */
139 unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h,
140  const char* filename,
141  LodePNGColorType colortype, unsigned bitdepth);
142 
143 /*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.*/
144 unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h,
145  const char* filename);
146 
147 /*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.*/
148 unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h,
149  const char* filename);
150 #endif /*LODEPNG_COMPILE_DISK*/
151 #endif /*LODEPNG_COMPILE_DECODER*/
152 
153 
154 #ifdef LODEPNG_COMPILE_ENCODER
155 /*
156 Converts raw pixel data into a PNG image in memory. The colortype and bitdepth
157  of the output PNG image cannot be chosen, they are automatically determined
158  by the colortype, bitdepth and content of the input pixel data.
159  Note: for 16-bit per channel colors, needs big endian format like PNG does.
160 out: Output parameter. Pointer to buffer that will contain the PNG image data.
161  Must be freed after usage with free(*out).
162 outsize: Output parameter. Pointer to the size in bytes of the out buffer.
163 image: The raw pixel data to encode. The size of this buffer should be
164  w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth.
165 w: width of the raw pixel data in pixels.
166 h: height of the raw pixel data in pixels.
167 colortype: the color type of the raw input image. See explanation on PNG color types.
168 bitdepth: the bit depth of the raw input image. See explanation on PNG color types.
169 Return value: LodePNG error code (0 means no error).
170 */
171 unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize,
172  const unsigned char* image, unsigned w, unsigned h,
173  LodePNGColorType colortype, unsigned bitdepth);
174 
175 /*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/
176 unsigned lodepng_encode32(unsigned char** out, size_t* outsize,
177  const unsigned char* image, unsigned w, unsigned h);
178 
179 /*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/
180 unsigned lodepng_encode24(unsigned char** out, size_t* outsize,
181  const unsigned char* image, unsigned w, unsigned h);
182 
183 #ifdef LODEPNG_COMPILE_DISK
184 /*
185 Converts raw pixel data into a PNG file on disk.
186 Same as the other encode functions, but instead takes a filename as output.
187 NOTE: This overwrites existing files without warning!
188 */
189 unsigned lodepng_encode_file(const char* filename,
190  const unsigned char* image, unsigned w, unsigned h,
191  LodePNGColorType colortype, unsigned bitdepth);
192 
193 /*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.*/
194 unsigned lodepng_encode32_file(const char* filename,
195  const unsigned char* image, unsigned w, unsigned h);
196 
197 /*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.*/
198 unsigned lodepng_encode24_file(const char* filename,
199  const unsigned char* image, unsigned w, unsigned h);
200 #endif /*LODEPNG_COMPILE_DISK*/
201 #endif /*LODEPNG_COMPILE_ENCODER*/
202 
203 
204 #ifdef LODEPNG_COMPILE_CPP
205 namespace lodepng
206 {
207 #ifdef LODEPNG_COMPILE_DECODER
208 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype
209 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/
210 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
211  const unsigned char* in, size_t insize,
212  LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
213 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
214  const std::vector<unsigned char>& in,
215  LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
216 #ifdef LODEPNG_COMPILE_DISK
217 /*
218 Converts PNG file from disk to raw pixel data in memory.
219 Same as the other decode functions, but instead takes a filename as input.
220 */
221 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
222  const std::string& filename,
223  LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
224 #endif /* LODEPNG_COMPILE_DISK */
225 #endif /* LODEPNG_COMPILE_DECODER */
226 
227 #ifdef LODEPNG_COMPILE_ENCODER
228 /*Same as lodepng_encode_memory, but encodes to an std::vector. colortype
229 is that of the raw input data. The output PNG color type will be auto chosen.*/
230 unsigned encode(std::vector<unsigned char>& out,
231  const unsigned char* in, unsigned w, unsigned h,
232  LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
233 unsigned encode(std::vector<unsigned char>& out,
234  const std::vector<unsigned char>& in, unsigned w, unsigned h,
235  LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
236 #ifdef LODEPNG_COMPILE_DISK
237 /*
238 Converts 32-bit RGBA raw pixel data into a PNG file on disk.
239 Same as the other encode functions, but instead takes a filename as output.
240 NOTE: This overwrites existing files without warning!
241 */
242 unsigned encode(const std::string& filename,
243  const unsigned char* in, unsigned w, unsigned h,
244  LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
245 unsigned encode(const std::string& filename,
246  const std::vector<unsigned char>& in, unsigned w, unsigned h,
247  LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8);
248 #endif /* LODEPNG_COMPILE_DISK */
249 #endif /* LODEPNG_COMPILE_ENCODER */
250 } /* namespace lodepng */
251 #endif /*LODEPNG_COMPILE_CPP*/
252 #endif /*LODEPNG_COMPILE_PNG*/
253 
254 #ifdef LODEPNG_COMPILE_ERROR_TEXT
255 /*Returns an English description of the numerical error code.*/
256 const char* lodepng_error_text(unsigned code);
257 #endif /*LODEPNG_COMPILE_ERROR_TEXT*/
258 
259 #ifdef LODEPNG_COMPILE_DECODER
260 /*Settings for zlib decompression*/
263 {
264  /* Check LodePNGDecoderSettings for more ignorable errors */
265  unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/
266 
267  /*use custom zlib decoder instead of built in one (default: null)*/
268  unsigned (*custom_zlib)(unsigned char**, size_t*,
269  const unsigned char*, size_t,
271  /*use custom deflate decoder instead of built in one (default: null)
272  if custom_zlib is used, custom_deflate is ignored since only the built in
273  zlib function will call custom_deflate*/
274  unsigned (*custom_inflate)(unsigned char**, size_t*,
275  const unsigned char*, size_t,
277 
278  const void* custom_context; /*optional custom settings for custom functions*/
279 };
280 
283 #endif /*LODEPNG_COMPILE_DECODER*/
284 
285 #ifdef LODEPNG_COMPILE_ENCODER
286 /*
287 Settings for zlib compression. Tweaking these settings tweaks the balance
288 between speed and compression ratio.
289 */
291 struct LodePNGCompressSettings /*deflate = compress*/
292 {
293  /*LZ77 related settings*/
294  unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/
295  unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/
296  unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/
297  unsigned minmatch; /*mininum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/
298  unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/
299  unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/
300 
301  /*use custom zlib encoder instead of built in one (default: null)*/
302  unsigned (*custom_zlib)(unsigned char**, size_t*,
303  const unsigned char*, size_t,
304  const LodePNGCompressSettings*);
305  /*use custom deflate encoder instead of built in one (default: null)
306  if custom_zlib is used, custom_deflate is ignored since only the built in
307  zlib function will call custom_deflate*/
308  unsigned (*custom_deflate)(unsigned char**, size_t*,
309  const unsigned char*, size_t,
310  const LodePNGCompressSettings*);
311 
312  const void* custom_context; /*optional custom settings for custom functions*/
313 };
314 
317 #endif /*LODEPNG_COMPILE_ENCODER*/
318 
319 #ifdef LODEPNG_COMPILE_PNG
320 /*
321 Color mode of an image. Contains all information required to decode the pixel
322 bits to RGBA colors. This information is the same as used in the PNG file
323 format, and is used both for PNG and raw image data in LodePNG.
324 */
325 typedef struct LodePNGColorMode
326 {
327  /*header (IHDR)*/
328  LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/
329  unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/
330 
331  /*
332  palette (PLTE and tRNS)
333 
334  Dynamically allocated with the colors of the palette, including alpha.
335  When encoding a PNG, to store your colors in the palette of the LodePNGColorMode, first use
336  lodepng_palette_clear, then for each color use lodepng_palette_add.
337  If you encode an image without alpha with palette, don't forget to put value 255 in each A byte of the palette.
338 
339  When decoding, by default you can ignore this palette, since LodePNG already
340  fills the palette colors in the pixels of the raw RGBA output.
341 
342  The palette is only supported for color type 3.
343  */
344  unsigned char* palette; /*palette in RGBARGBA... order. When allocated, must be either 0, or have size 1024*/
345  size_t palettesize; /*palette size in number of colors (amount of bytes is 4 * palettesize)*/
346 
347  /*
348  transparent color key (tRNS)
349 
350  This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit.
351  For greyscale PNGs, r, g and b will all 3 be set to the same.
352 
353  When decoding, by default you can ignore this information, since LodePNG sets
354  pixels with this key to transparent already in the raw RGBA output.
355 
356  The color key is only supported for color types 0 and 2.
357  */
358  unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/
359  unsigned key_r; /*red/greyscale component of color key*/
360  unsigned key_g; /*green component of color key*/
361  unsigned key_b; /*blue component of color key*/
363 
364 /*init, cleanup and copy functions to use with this struct*/
367 /*return value is error code (0 means no error)*/
368 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source);
369 
371 /*add 1 color to the palette*/
373  unsigned char r, unsigned char g, unsigned char b, unsigned char a);
374 
375 /*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/
376 unsigned lodepng_get_bpp(const LodePNGColorMode* info);
377 /*get the amount of color channels used, based on colortype in the struct.
378 If a palette is used, it counts as 1 channel.*/
379 unsigned lodepng_get_channels(const LodePNGColorMode* info);
380 /*is it a greyscale type? (only colortype 0 or 4)*/
381 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info);
382 /*has it got an alpha channel? (only colortype 2 or 6)*/
383 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info);
384 /*has it got a palette? (only colortype 3)*/
385 unsigned lodepng_is_palette_type(const LodePNGColorMode* info);
386 /*only returns true if there is a palette and there is a value in the palette with alpha < 255.
387 Loops through the palette to check this.*/
388 unsigned lodepng_has_palette_alpha(const LodePNGColorMode* info);
389 /*
390 Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image.
391 Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels).
392 Returns false if the image can only have opaque pixels.
393 In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values,
394 or if "key_defined" is true.
395 */
396 unsigned lodepng_can_have_alpha(const LodePNGColorMode* info);
397 /*Returns the byte size of a raw image buffer with given width, height and color mode*/
398 size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color);
399 
400 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
401 /*The information of a Time chunk in PNG.*/
402 typedef struct LodePNGTime
403 {
404  unsigned year; /*2 bytes used (0-65535)*/
405  unsigned month; /*1-12*/
406  unsigned day; /*1-31*/
407  unsigned hour; /*0-23*/
408  unsigned minute; /*0-59*/
409  unsigned second; /*0-60 (to allow for leap seconds)*/
410 } LodePNGTime;
411 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
412 
413 /*Information about the PNG image, except pixels, width and height.*/
414 typedef struct LodePNGInfo
415 {
416  /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/
417  unsigned compression_method;/*compression method of the original file. Always 0.*/
418  unsigned filter_method; /*filter method of the original file*/
419  unsigned interlace_method; /*interlace method of the original file*/
420  LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/
421 
422 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
423  /*
424  suggested background color chunk (bKGD)
425  This color uses the same color mode as the PNG (except alpha channel), which can be 1-bit to 16-bit.
426 
427  For greyscale PNGs, r, g and b will all 3 be set to the same. When encoding
428  the encoder writes the red one. For palette PNGs: When decoding, the RGB value
429  will be stored, not a palette index. But when encoding, specify the index of
430  the palette in background_r, the other two are then ignored.
431 
432  The decoder does not use this background color to edit the color of pixels.
433  */
434  unsigned background_defined; /*is a suggested background color given?*/
435  unsigned background_r; /*red component of suggested background color*/
436  unsigned background_g; /*green component of suggested background color*/
437  unsigned background_b; /*blue component of suggested background color*/
438 
439  /*
440  non-international text chunks (tEXt and zTXt)
441 
442  The char** arrays each contain num strings. The actual messages are in
443  text_strings, while text_keys are keywords that give a short description what
444  the actual text represents, e.g. Title, Author, Description, or anything else.
445 
446  A keyword is minimum 1 character and maximum 79 characters long. It's
447  discouraged to use a single line length longer than 79 characters for texts.
448 
449  Don't allocate these text buffers yourself. Use the init/cleanup functions
450  correctly and use lodepng_add_text and lodepng_clear_text.
451  */
452  size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/
453  char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/
454  char** text_strings; /*the actual text*/
455 
456  /*
457  international text chunks (iTXt)
458  Similar to the non-international text chunks, but with additional strings
459  "langtags" and "transkeys".
460  */
461  size_t itext_num; /*the amount of international texts in this PNG*/
462  char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/
463  char** itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/
464  char** itext_transkeys; /*keyword translated to the international language - UTF-8 string*/
465  char** itext_strings; /*the actual international text - UTF-8 string*/
466 
467  /*time chunk (tIME)*/
468  unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/
470 
471  /*phys chunk (pHYs)*/
472  unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/
473  unsigned phys_x; /*pixels per unit in x direction*/
474  unsigned phys_y; /*pixels per unit in y direction*/
475  unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/
476 
477  /*
478  unknown chunks
479  There are 3 buffers, one for each position in the PNG where unknown chunks can appear
480  each buffer contains all unknown chunks for that position consecutively
481  The 3 buffers are the unknown chunks between certain critical chunks:
482  0: IHDR-PLTE, 1: PLTE-IDAT, 2: IDAT-IEND
483  Do not allocate or traverse this data yourself. Use the chunk traversing functions declared
484  later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct.
485  */
486  unsigned char* unknown_chunks_data[3];
487  size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/
488 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
489 } LodePNGInfo;
490 
491 /*init, cleanup and copy functions to use with this struct*/
492 void lodepng_info_init(LodePNGInfo* info);
494 /*return value is error code (0 means no error)*/
495 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source);
496 
497 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
498 void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
499 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/
500 
501 void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/
502 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
503  const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/
504 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
505 
506 /*
507 Converts raw buffer from one color type to another color type, based on
508 LodePNGColorMode structs to describe the input and output color type.
509 See the reference manual at the end of this header file to see which color conversions are supported.
510 return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported)
511 The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel
512 of the output color type (lodepng_get_bpp).
513 For < 8 bpp images, there should not be padding bits at the end of scanlines.
514 For 16-bit per channel colors, uses big endian format like PNG does.
515 Return value is LodePNG error code
516 */
517 unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
518  const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in,
519  unsigned w, unsigned h);
520 
521 #ifdef LODEPNG_COMPILE_DECODER
522 /*
523 Settings for the decoder. This contains settings for the PNG and the Zlib
524 decoder, but not the Info settings from the Info structs.
525 */
527 {
528  LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/
529 
530  /* Check LodePNGDecompressSettings for more ignorable errors */
531  unsigned ignore_crc; /*ignore CRC checksums*/
532  unsigned ignore_critical; /*ignore unknown critical chunks*/
533  unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/
534 
535  unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/
536 
537 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
538  unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/
539  /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/
541 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
543 
545 #endif /*LODEPNG_COMPILE_DECODER*/
546 
547 #ifdef LODEPNG_COMPILE_ENCODER
548 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/
550 {
551  /*every filter at zero*/
553  /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/
555  /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending
556  on the image, this is better or worse than minsum.*/
558  /*
559  Brute-force-search PNG filters by compressing each filter for each scanline.
560  Experimental, very slow, and only rarely gives better compression than MINSUM.
561  */
563  /*use predefined_filters buffer: you specify the filter type for each scanline*/
566 
567 /*Gives characteristics about the colors of the image, which helps decide which color model to use for encoding.
568 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/
569 typedef struct LodePNGColorProfile
570 {
571  unsigned colored; /*not greyscale*/
572  unsigned key; /*image is not opaque and color key is possible instead of full alpha*/
573  unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/
574  unsigned short key_g;
575  unsigned short key_b;
576  unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/
577  unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16.*/
578  unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order*/
579  unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for greyscale only. 16 if 16-bit per channel required.*/
581 
583 
584 /*Get a LodePNGColorProfile of the image.*/
586  const unsigned char* image, unsigned w, unsigned h,
587  const LodePNGColorMode* mode_in);
588 /*The function LodePNG uses internally to decide the PNG color with auto_convert.
589 Chooses an optimal color model, e.g. grey if only grey pixels, palette if < 256 colors, ...*/
591  const unsigned char* image, unsigned w, unsigned h,
592  const LodePNGColorMode* mode_in);
593 
594 /*Settings for the encoder.*/
596 {
597  LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/
598 
599  unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/
600 
601  /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than
602  8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to
603  completely follow the official PNG heuristic, filter_palette_zero must be true and
604  filter_strategy must be LFS_MINSUM*/
606  /*Which filter strategy to use when not using zeroes due to filter_palette_zero.
607  Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/
609  /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with
610  the same length as the amount of scanlines in the image, and each value must <= 5. You
611  have to cleanup this buffer, LodePNG will never free it. Don't forget that filter_palette_zero
612  must be set to 0 to ensure this is also used on palette or low bitdepth images.*/
613  const unsigned char* predefined_filters;
614 
615  /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette).
616  If colortype is 3, PLTE is _always_ created.*/
617  unsigned force_palette;
618 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
619  /*add LodePNG identifier and version as a text chunk, for debugging*/
620  unsigned add_id;
621  /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/
623 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
625 
627 #endif /*LODEPNG_COMPILE_ENCODER*/
628 
629 
630 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER)
631 /*The settings, state and information for extended encoding and decoding.*/
632 typedef struct LodePNGState
633 {
634 #ifdef LODEPNG_COMPILE_DECODER
635  LodePNGDecoderSettings decoder; /*the decoding settings*/
636 #endif /*LODEPNG_COMPILE_DECODER*/
637 #ifdef LODEPNG_COMPILE_ENCODER
638  LodePNGEncoderSettings encoder; /*the encoding settings*/
639 #endif /*LODEPNG_COMPILE_ENCODER*/
640  LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/
641  LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/
642  unsigned error;
643 #ifdef LODEPNG_COMPILE_CPP
644  /* For the lodepng::State subclass. */
645  virtual ~LodePNGState(){}
646 #endif
647 } LodePNGState;
648 
649 /*init, cleanup and copy functions to use with this struct*/
650 void lodepng_state_init(LodePNGState* state);
652 void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source);
653 #endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */
654 
655 #ifdef LODEPNG_COMPILE_DECODER
656 /*
657 Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and
658 getting much more information about the PNG image and color mode.
659 */
660 unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
661  LodePNGState* state,
662  const unsigned char* in, size_t insize);
663 
664 /*
665 Read the PNG header, but not the actual data. This returns only the information
666 that is in the header chunk of the PNG, such as width, height and color type. The
667 information is placed in the info_png field of the LodePNGState.
668 */
669 unsigned lodepng_inspect(unsigned* w, unsigned* h,
670  LodePNGState* state,
671  const unsigned char* in, size_t insize);
672 #endif /*LODEPNG_COMPILE_DECODER*/
673 
674 
675 #ifdef LODEPNG_COMPILE_ENCODER
676 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/
677 unsigned lodepng_encode(unsigned char** out, size_t* outsize,
678  const unsigned char* image, unsigned w, unsigned h,
679  LodePNGState* state);
680 #endif /*LODEPNG_COMPILE_ENCODER*/
681 
682 /*
683 The lodepng_chunk functions are normally not needed, except to traverse the
684 unknown chunks stored in the LodePNGInfo struct, or add new ones to it.
685 It also allows traversing the chunks of an encoded PNG file yourself.
686 
687 PNG standard chunk naming conventions:
688 First byte: uppercase = critical, lowercase = ancillary
689 Second byte: uppercase = public, lowercase = private
690 Third byte: must be uppercase
691 Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy
692 */
693 
694 /*
695 Gets the length of the data of the chunk. Total chunk length has 12 bytes more.
696 There must be at least 4 bytes to read from. If the result value is too large,
697 it may be corrupt data.
698 */
699 unsigned lodepng_chunk_length(const unsigned char* chunk);
700 
701 /*puts the 4-byte type in null terminated string*/
702 void lodepng_chunk_type(char type[5], const unsigned char* chunk);
703 
704 /*check if the type is the given type*/
705 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type);
706 
707 /*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/
708 unsigned char lodepng_chunk_ancillary(const unsigned char* chunk);
709 
710 /*0: public, 1: private (see PNG standard)*/
711 unsigned char lodepng_chunk_private(const unsigned char* chunk);
712 
713 /*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/
714 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk);
715 
716 /*get pointer to the data of the chunk, where the input points to the header of the chunk*/
717 unsigned char* lodepng_chunk_data(unsigned char* chunk);
718 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk);
719 
720 /*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/
721 unsigned lodepng_chunk_check_crc(const unsigned char* chunk);
722 
723 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/
724 void lodepng_chunk_generate_crc(unsigned char* chunk);
725 
726 /*iterate to next chunks. don't use on IEND chunk, as there is no next chunk then*/
727 unsigned char* lodepng_chunk_next(unsigned char* chunk);
728 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk);
729 
730 /*
731 Appends chunk to the data in out. The given chunk should already have its chunk header.
732 The out variable and outlength are updated to reflect the new reallocated buffer.
733 Returns error code (0 if it went ok)
734 */
735 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk);
736 
737 /*
738 Appends new chunk to out. The chunk to append is given by giving its length, type
739 and data separately. The type is a 4-letter string.
740 The out variable and outlength are updated to reflect the new reallocated buffer.
741 Returne error code (0 if it went ok)
742 */
743 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length,
744  const char* type, const unsigned char* data);
745 
746 
747 /*Calculate CRC32 of buffer*/
748 unsigned lodepng_crc32(const unsigned char* buf, size_t len);
749 #endif /*LODEPNG_COMPILE_PNG*/
750 
751 
752 #ifdef LODEPNG_COMPILE_ZLIB
753 /*
754 This zlib part can be used independently to zlib compress and decompress a
755 buffer. It cannot be used to create gzip files however, and it only supports the
756 part of zlib that is required for PNG, it does not support dictionaries.
757 */
758 
759 #ifdef LODEPNG_COMPILE_DECODER
760 /*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/
761 unsigned lodepng_inflate(unsigned char** out, size_t* outsize,
762  const unsigned char* in, size_t insize,
764 
765 /*
766 Decompresses Zlib data. Reallocates the out buffer and appends the data. The
767 data must be according to the zlib specification.
768 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid
769 buffer and *outsize its size in bytes. out must be freed by user after usage.
770 */
771 unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize,
772  const unsigned char* in, size_t insize,
773  const LodePNGDecompressSettings* settings);
774 #endif /*LODEPNG_COMPILE_DECODER*/
775 
776 #ifdef LODEPNG_COMPILE_ENCODER
777 /*
778 Compresses data with Zlib. Reallocates the out buffer and appends the data.
779 Zlib adds a small header and trailer around the deflate data.
780 The data is output in the format of the zlib specification.
781 Either, *out must be NULL and *outsize must be 0, or, *out must be a valid
782 buffer and *outsize its size in bytes. out must be freed by user after usage.
783 */
784 unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize,
785  const unsigned char* in, size_t insize,
786  const LodePNGCompressSettings* settings);
787 
788 /*
789 Find length-limited Huffman code for given frequencies. This function is in the
790 public interface only for tests, it's used internally by lodepng_deflate.
791 */
792 unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies,
793  size_t numcodes, unsigned maxbitlen);
794 
795 /*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/
796 unsigned lodepng_deflate(unsigned char** out, size_t* outsize,
797  const unsigned char* in, size_t insize,
798  const LodePNGCompressSettings* settings);
799 
800 #endif /*LODEPNG_COMPILE_ENCODER*/
801 #endif /*LODEPNG_COMPILE_ZLIB*/
802 
803 #ifdef LODEPNG_COMPILE_DISK
804 /*
805 Load a file from disk into buffer. The function allocates the out buffer, and
806 after usage you should free it.
807 out: output parameter, contains pointer to loaded buffer.
808 outsize: output parameter, size of the allocated out buffer
809 filename: the path to the file to load
810 return value: error code (0 means ok)
811 */
812 unsigned lodepng_load_file(unsigned char** out, size_t* outsize, const char* filename);
813 
814 /*
815 Save a file from buffer to disk. Warning, if it exists, this function overwrites
816 the file without warning!
817 buffer: the buffer to write
818 buffersize: size of the buffer to write
819 filename: the path to the file to save to
820 return value: error code (0 means ok)
821 */
822 unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename);
823 #endif /*LODEPNG_COMPILE_DISK*/
824 
825 #ifdef LODEPNG_COMPILE_CPP
826 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */
827 namespace lodepng
828 {
829 #ifdef LODEPNG_COMPILE_PNG
830 class State : public LodePNGState
831 {
832  public:
833  State();
834  State(const State& other);
835  virtual ~State();
836  State& operator=(const State& other);
837 };
838 
839 #ifdef LODEPNG_COMPILE_DECODER
840 /* Same as other lodepng::decode, but using a State for more settings and information. */
841 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
842  State& state,
843  const unsigned char* in, size_t insize);
844 unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
845  State& state,
846  const std::vector<unsigned char>& in);
847 #endif /*LODEPNG_COMPILE_DECODER*/
848 
849 #ifdef LODEPNG_COMPILE_ENCODER
850 /* Same as other lodepng::encode, but using a State for more settings and information. */
851 unsigned encode(std::vector<unsigned char>& out,
852  const unsigned char* in, unsigned w, unsigned h,
853  State& state);
854 unsigned encode(std::vector<unsigned char>& out,
855  const std::vector<unsigned char>& in, unsigned w, unsigned h,
856  State& state);
857 #endif /*LODEPNG_COMPILE_ENCODER*/
858 
859 #ifdef LODEPNG_COMPILE_DISK
860 /*
861 Load a file from disk into an std::vector.
862 return value: error code (0 means ok)
863 */
864 unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename);
865 
866 /*
867 Save the binary data in an std::vector to a file on disk. The file is overwritten
868 without warning.
869 */
870 unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename);
871 #endif /* LODEPNG_COMPILE_DISK */
872 #endif /* LODEPNG_COMPILE_PNG */
873 
874 #ifdef LODEPNG_COMPILE_ZLIB
875 #ifdef LODEPNG_COMPILE_DECODER
876 /* Zlib-decompress an unsigned char buffer */
877 unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
878  const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings);
879 
880 /* Zlib-decompress an std::vector */
881 unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
882  const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings);
883 #endif /* LODEPNG_COMPILE_DECODER */
884 
885 #ifdef LODEPNG_COMPILE_ENCODER
886 /* Zlib-compress an unsigned char buffer */
887 unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize,
888  const LodePNGCompressSettings& settings = lodepng_default_compress_settings);
889 
890 /* Zlib-compress an std::vector */
891 unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
892  const LodePNGCompressSettings& settings = lodepng_default_compress_settings);
893 #endif /* LODEPNG_COMPILE_ENCODER */
894 #endif /* LODEPNG_COMPILE_ZLIB */
895 } /* namespace lodepng */
896 #endif /*LODEPNG_COMPILE_CPP*/
897 
898 /*
899 TODO:
900 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often
901 [.] check compatibility with various compilers - done but needs to be redone for every newer version
902 [X] converting color to 16-bit per channel types
903 [ ] read all public PNG chunk types (but never let the color profile and gamma ones touch RGB values)
904 [ ] make sure encoder generates no chunks with size > (2^31)-1
905 [ ] partial decoding (stream processing)
906 [X] let the "isFullyOpaque" function check color keys and transparent palettes too
907 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl"
908 [ ] don't stop decoding on errors like 69, 57, 58 (make warnings)
909 [ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ...
910 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes
911 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ...
912 [ ] allow user to give data (void*) to custom allocator
913 */
914 
915 #endif /*LODEPNG_H inclusion guard*/
916 
917 /*
918 LodePNG Documentation
919 ---------------------
920 
921 0. table of contents
922 --------------------
923 
924  1. about
925  1.1. supported features
926  1.2. features not supported
927  2. C and C++ version
928  3. security
929  4. decoding
930  5. encoding
931  6. color conversions
932  6.1. PNG color types
933  6.2. color conversions
934  6.3. padding bits
935  6.4. A note about 16-bits per channel and endianness
936  7. error values
937  8. chunks and PNG editing
938  9. compiler support
939  10. examples
940  10.1. decoder C++ example
941  10.2. decoder C example
942  11. state settings reference
943  12. changes
944  13. contact information
945 
946 
947 1. about
948 --------
949 
950 PNG is a file format to store raster images losslessly with good compression,
951 supporting different color types and alpha channel.
952 
953 LodePNG is a PNG codec according to the Portable Network Graphics (PNG)
954 Specification (Second Edition) - W3C Recommendation 10 November 2003.
955 
956 The specifications used are:
957 
958 *) Portable Network Graphics (PNG) Specification (Second Edition):
959  http://www.w3.org/TR/2003/REC-PNG-20031110
960 *) RFC 1950 ZLIB Compressed Data Format version 3.3:
961  http://www.gzip.org/zlib/rfc-zlib.html
962 *) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3:
963  http://www.gzip.org/zlib/rfc-deflate.html
964 
965 The most recent version of LodePNG can currently be found at
966 http://lodev.org/lodepng/
967 
968 LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds
969 extra functionality.
970 
971 LodePNG exists out of two files:
972 -lodepng.h: the header file for both C and C++
973 -lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage
974 
975 If you want to start using LodePNG right away without reading this doc, get the
976 examples from the LodePNG website to see how to use it in code, or check the
977 smaller examples in chapter 13 here.
978 
979 LodePNG is simple but only supports the basic requirements. To achieve
980 simplicity, the following design choices were made: There are no dependencies
981 on any external library. There are functions to decode and encode a PNG with
982 a single function call, and extended versions of these functions taking a
983 LodePNGState struct allowing to specify or get more information. By default
984 the colors of the raw image are always RGB or RGBA, no matter what color type
985 the PNG file uses. To read and write files, there are simple functions to
986 convert the files to/from buffers in memory.
987 
988 This all makes LodePNG suitable for loading textures in games, demos and small
989 programs, ... It's less suitable for full fledged image editors, loading PNGs
990 over network (it requires all the image data to be available before decoding can
991 begin), life-critical systems, ...
992 
993 1.1. supported features
994 -----------------------
995 
996 The following features are supported by the decoder:
997 
998 *) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image,
999  or the same color type as the PNG
1000 *) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image
1001 *) Adam7 interlace and deinterlace for any color type
1002 *) loading the image from harddisk or decoding it from a buffer from other sources than harddisk
1003 *) support for alpha channels, including RGBA color model, translucent palettes and color keying
1004 *) zlib decompression (inflate)
1005 *) zlib compression (deflate)
1006 *) CRC32 and ADLER32 checksums
1007 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks.
1008 *) the following chunks are supported (generated/interpreted) by both encoder and decoder:
1009  IHDR: header information
1010  PLTE: color palette
1011  IDAT: pixel data
1012  IEND: the final chunk
1013  tRNS: transparency for palettized images
1014  tEXt: textual information
1015  zTXt: compressed textual information
1016  iTXt: international textual information
1017  bKGD: suggested background color
1018  pHYs: physical dimensions
1019  tIME: modification time
1020 
1021 1.2. features not supported
1022 ---------------------------
1023 
1024 The following features are _not_ supported:
1025 
1026 *) some features needed to make a conformant PNG-Editor might be still missing.
1027 *) partial loading/stream processing. All data must be available and is processed in one call.
1028 *) The following public chunks are not supported but treated as unknown chunks by LodePNG
1029  cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT
1030  Some of these are not supported on purpose: LodePNG wants to provide the RGB values
1031  stored in the pixels, not values modified by system dependent gamma or color models.
1032 
1033 
1034 2. C and C++ version
1035 --------------------
1036 
1037 The C version uses buffers allocated with alloc that you need to free()
1038 yourself. You need to use init and cleanup functions for each struct whenever
1039 using a struct from the C version to avoid exploits and memory leaks.
1040 
1041 The C++ version has extra functions with std::vectors in the interface and the
1042 lodepng::State class which is a LodePNGState with constructor and destructor.
1043 
1044 These files work without modification for both C and C++ compilers because all
1045 the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers
1046 ignore it, and the C code is made to compile both with strict ISO C90 and C++.
1047 
1048 To use the C++ version, you need to rename the source file to lodepng.cpp
1049 (instead of lodepng.c), and compile it with a C++ compiler.
1050 
1051 To use the C version, you need to rename the source file to lodepng.c (instead
1052 of lodepng.cpp), and compile it with a C compiler.
1053 
1054 
1055 3. Security
1056 -----------
1057 
1058 Even if carefully designed, it's always possible that LodePNG contains possible
1059 exploits. If you discover one, please let me know, and it will be fixed.
1060 
1061 When using LodePNG, care has to be taken with the C version of LodePNG, as well
1062 as the C-style structs when working with C++. The following conventions are used
1063 for all C-style structs:
1064 
1065 -if a struct has a corresponding init function, always call the init function when making a new one
1066 -if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks
1067 -if a struct has a corresponding copy function, use the copy function instead of "=".
1068  The destination must also be inited already.
1069 
1070 
1071 4. Decoding
1072 -----------
1073 
1074 Decoding converts a PNG compressed image to a raw pixel buffer.
1075 
1076 Most documentation on using the decoder is at its declarations in the header
1077 above. For C, simple decoding can be done with functions such as
1078 lodepng_decode32, and more advanced decoding can be done with the struct
1079 LodePNGState and lodepng_decode. For C++, all decoding can be done with the
1080 various lodepng::decode functions, and lodepng::State can be used for advanced
1081 features.
1082 
1083 When using the LodePNGState, it uses the following fields for decoding:
1084 *) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here
1085 *) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get
1086 *) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use
1087 
1088 LodePNGInfo info_png
1089 --------------------
1090 
1091 After decoding, this contains extra information of the PNG image, except the actual
1092 pixels, width and height because these are already gotten directly from the decoder
1093 functions.
1094 
1095 It contains for example the original color type of the PNG image, text comments,
1096 suggested background color, etc... More details about the LodePNGInfo struct are
1097 at its declaration documentation.
1098 
1099 LodePNGColorMode info_raw
1100 -------------------------
1101 
1102 When decoding, here you can specify which color type you want
1103 the resulting raw image to be. If this is different from the colortype of the
1104 PNG, then the decoder will automatically convert the result. This conversion
1105 always works, except if you want it to convert a color PNG to greyscale or to
1106 a palette with missing colors.
1107 
1108 By default, 32-bit color is used for the result.
1109 
1110 LodePNGDecoderSettings decoder
1111 ------------------------------
1112 
1113 The settings can be used to ignore the errors created by invalid CRC and Adler32
1114 chunks, and to disable the decoding of tEXt chunks.
1115 
1116 There's also a setting color_convert, true by default. If false, no conversion
1117 is done, the resulting data will be as it was in the PNG (after decompression)
1118 and you'll have to puzzle the colors of the pixels together yourself using the
1119 color type information in the LodePNGInfo.
1120 
1121 
1122 5. Encoding
1123 -----------
1124 
1125 Encoding converts a raw pixel buffer to a PNG compressed image.
1126 
1127 Most documentation on using the encoder is at its declarations in the header
1128 above. For C, simple encoding can be done with functions such as
1129 lodepng_encode32, and more advanced decoding can be done with the struct
1130 LodePNGState and lodepng_encode. For C++, all encoding can be done with the
1131 various lodepng::encode functions, and lodepng::State can be used for advanced
1132 features.
1133 
1134 Like the decoder, the encoder can also give errors. However it gives less errors
1135 since the encoder input is trusted, the decoder input (a PNG image that could
1136 be forged by anyone) is not trusted.
1137 
1138 When using the LodePNGState, it uses the following fields for encoding:
1139 *) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be.
1140 *) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has
1141 *) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use
1142 
1143 LodePNGInfo info_png
1144 --------------------
1145 
1146 When encoding, you use this the opposite way as when decoding: for encoding,
1147 you fill in the values you want the PNG to have before encoding. By default it's
1148 not needed to specify a color type for the PNG since it's automatically chosen,
1149 but it's possible to choose it yourself given the right settings.
1150 
1151 The encoder will not always exactly match the LodePNGInfo struct you give,
1152 it tries as close as possible. Some things are ignored by the encoder. The
1153 encoder uses, for example, the following settings from it when applicable:
1154 colortype and bitdepth, text chunks, time chunk, the color key, the palette, the
1155 background color, the interlace method, unknown chunks, ...
1156 
1157 When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk.
1158 If the palette contains any colors for which the alpha channel is not 255 (so
1159 there are translucent colors in the palette), it'll add a tRNS chunk.
1160 
1161 LodePNGColorMode info_raw
1162 -------------------------
1163 
1164 You specify the color type of the raw image that you give to the input here,
1165 including a possible transparent color key and palette you happen to be using in
1166 your raw image data.
1167 
1168 By default, 32-bit color is assumed, meaning your input has to be in RGBA
1169 format with 4 bytes (unsigned chars) per pixel.
1170 
1171 LodePNGEncoderSettings encoder
1172 ------------------------------
1173 
1174 The following settings are supported (some are in sub-structs):
1175 *) auto_convert: when this option is enabled, the encoder will
1176 automatically choose the smallest possible color mode (including color key) that
1177 can encode the colors of all pixels without information loss.
1178 *) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree,
1179  2 = dynamic huffman tree (best compression). Should be 2 for proper
1180  compression.
1181 *) use_lz77: whether or not to use LZ77 for compressed block types. Should be
1182  true for proper compression.
1183 *) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value
1184  2048 by default, but can be set to 32768 for better, but slow, compression.
1185 *) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE
1186  chunk if force_palette is true. This can used as suggested palette to convert
1187  to by viewers that don't support more than 256 colors (if those still exist)
1188 *) add_id: add text chunk "Encoder: LodePNG <version>" to the image.
1189 *) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks.
1190  zTXt chunks use zlib compression on the text. This gives a smaller result on
1191  large texts but a larger result on small texts (such as a single program name).
1192  It's all tEXt or all zTXt though, there's no separate setting per text yet.
1193 
1194 
1195 6. color conversions
1196 --------------------
1197 
1198 An important thing to note about LodePNG, is that the color type of the PNG, and
1199 the color type of the raw image, are completely independent. By default, when
1200 you decode a PNG, you get the result as a raw image in the color type you want,
1201 no matter whether the PNG was encoded with a palette, greyscale or RGBA color.
1202 And if you encode an image, by default LodePNG will automatically choose the PNG
1203 color type that gives good compression based on the values of colors and amount
1204 of colors in the image. It can be configured to let you control it instead as
1205 well, though.
1206 
1207 To be able to do this, LodePNG does conversions from one color mode to another.
1208 It can convert from almost any color type to any other color type, except the
1209 following conversions: RGB to greyscale is not supported, and converting to a
1210 palette when the palette doesn't have a required color is not supported. This is
1211 not supported on purpose: this is information loss which requires a color
1212 reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to grey
1213 is easy, but there are multiple ways if you want to give some channels more
1214 weight).
1215 
1216 By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB
1217 color, no matter what color type the PNG has. And by default when encoding,
1218 LodePNG automatically picks the best color model for the output PNG, and expects
1219 the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control
1220 the color format of the images yourself, you can skip this chapter.
1221 
1222 6.1. PNG color types
1223 --------------------
1224 
1225 A PNG image can have many color types, ranging from 1-bit color to 64-bit color,
1226 as well as palettized color modes. After the zlib decompression and unfiltering
1227 in the PNG image is done, the raw pixel data will have that color type and thus
1228 a certain amount of bits per pixel. If you want the output raw image after
1229 decoding to have another color type, a conversion is done by LodePNG.
1230 
1231 The PNG specification gives the following color types:
1232 
1233 0: greyscale, bit depths 1, 2, 4, 8, 16
1234 2: RGB, bit depths 8 and 16
1235 3: palette, bit depths 1, 2, 4 and 8
1236 4: greyscale with alpha, bit depths 8 and 16
1237 6: RGBA, bit depths 8 and 16
1238 
1239 Bit depth is the amount of bits per pixel per color channel. So the total amount
1240 of bits per pixel is: amount of channels * bitdepth.
1241 
1242 6.2. color conversions
1243 ----------------------
1244 
1245 As explained in the sections about the encoder and decoder, you can specify
1246 color types and bit depths in info_png and info_raw to change the default
1247 behaviour.
1248 
1249 If, when decoding, you want the raw image to be something else than the default,
1250 you need to set the color type and bit depth you want in the LodePNGColorMode,
1251 or the parameters colortype and bitdepth of the simple decoding function.
1252 
1253 If, when encoding, you use another color type than the default in the raw input
1254 image, you need to specify its color type and bit depth in the LodePNGColorMode
1255 of the raw image, or use the parameters colortype and bitdepth of the simple
1256 encoding function.
1257 
1258 If, when encoding, you don't want LodePNG to choose the output PNG color type
1259 but control it yourself, you need to set auto_convert in the encoder settings
1260 to false, and specify the color type you want in the LodePNGInfo of the
1261 encoder (including palette: it can generate a palette if auto_convert is true,
1262 otherwise not).
1263 
1264 If the input and output color type differ (whether user chosen or auto chosen),
1265 LodePNG will do a color conversion, which follows the rules below, and may
1266 sometimes result in an error.
1267 
1268 To avoid some confusion:
1269 -the decoder converts from PNG to raw image
1270 -the encoder converts from raw image to PNG
1271 -the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image
1272 -the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG
1273 -when encoding, the color type in LodePNGInfo is ignored if auto_convert
1274  is enabled, it is automatically generated instead
1275 -when decoding, the color type in LodePNGInfo is set by the decoder to that of the original
1276  PNG image, but it can be ignored since the raw image has the color type you requested instead
1277 -if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion
1278  between the color types is done if the color types are supported. If it is not
1279  supported, an error is returned. If the types are the same, no conversion is done.
1280 -even though some conversions aren't supported, LodePNG supports loading PNGs from any
1281  colortype and saving PNGs to any colortype, sometimes it just requires preparing
1282  the raw image correctly before encoding.
1283 -both encoder and decoder use the same color converter.
1284 
1285 Non supported color conversions:
1286 -color to greyscale: no error is thrown, but the result will look ugly because
1287 only the red channel is taken
1288 -anything to palette when that palette does not have that color in it: in this
1289 case an error is thrown
1290 
1291 Supported color conversions:
1292 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA
1293 -any grey or grey+alpha, to grey or grey+alpha
1294 -anything to a palette, as long as the palette has the requested colors in it
1295 -removing alpha channel
1296 -higher to smaller bitdepth, and vice versa
1297 
1298 If you want no color conversion to be done (e.g. for speed or control):
1299 -In the encoder, you can make it save a PNG with any color type by giving the
1300 raw color mode and LodePNGInfo the same color mode, and setting auto_convert to
1301 false.
1302 -In the decoder, you can make it store the pixel data in the same color type
1303 as the PNG has, by setting the color_convert setting to false. Settings in
1304 info_raw are then ignored.
1305 
1306 The function lodepng_convert does the color conversion. It is available in the
1307 interface but normally isn't needed since the encoder and decoder already call
1308 it.
1309 
1310 6.3. padding bits
1311 -----------------
1312 
1313 In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines
1314 have a bit amount that isn't a multiple of 8, then padding bits are used so that each
1315 scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output.
1316 The raw input image you give to the encoder, and the raw output image you get from the decoder
1317 will NOT have these padding bits, e.g. in the case of a 1-bit image with a width
1318 of 7 pixels, the first pixel of the second scanline will the the 8th bit of the first byte,
1319 not the first bit of a new byte.
1320 
1321 6.4. A note about 16-bits per channel and endianness
1322 ----------------------------------------------------
1323 
1324 LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like
1325 for any other color format. The 16-bit values are stored in big endian (most
1326 significant byte first) in these arrays. This is the opposite order of the
1327 little endian used by x86 CPU's.
1328 
1329 LodePNG always uses big endian because the PNG file format does so internally.
1330 Conversions to other formats than PNG uses internally are not supported by
1331 LodePNG on purpose, there are myriads of formats, including endianness of 16-bit
1332 colors, the order in which you store R, G, B and A, and so on. Supporting and
1333 converting to/from all that is outside the scope of LodePNG.
1334 
1335 This may mean that, depending on your use case, you may want to convert the big
1336 endian output of LodePNG to little endian with a for loop. This is certainly not
1337 always needed, many applications and libraries support big endian 16-bit colors
1338 anyway, but it means you cannot simply cast the unsigned char* buffer to an
1339 unsigned short* buffer on x86 CPUs.
1340 
1341 
1342 7. error values
1343 ---------------
1344 
1345 All functions in LodePNG that return an error code, return 0 if everything went
1346 OK, or a non-zero code if there was an error.
1347 
1348 The meaning of the LodePNG error values can be retrieved with the function
1349 lodepng_error_text: given the numerical error code, it returns a description
1350 of the error in English as a string.
1351 
1352 Check the implementation of lodepng_error_text to see the meaning of each code.
1353 
1354 
1355 8. chunks and PNG editing
1356 -------------------------
1357 
1358 If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG
1359 editor that should follow the rules about handling of unknown chunks, or if your
1360 program is able to read other types of chunks than the ones handled by LodePNG,
1361 then that's possible with the chunk functions of LodePNG.
1362 
1363 A PNG chunk has the following layout:
1364 
1365 4 bytes length
1366 4 bytes type name
1367 length bytes data
1368 4 bytes CRC
1369 
1370 8.1. iterating through chunks
1371 -----------------------------
1372 
1373 If you have a buffer containing the PNG image data, then the first chunk (the
1374 IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the
1375 signature of the PNG and are not part of a chunk. But if you start at byte 8
1376 then you have a chunk, and can check the following things of it.
1377 
1378 NOTE: none of these functions check for memory buffer boundaries. To avoid
1379 exploits, always make sure the buffer contains all the data of the chunks.
1380 When using lodepng_chunk_next, make sure the returned value is within the
1381 allocated memory.
1382 
1383 unsigned lodepng_chunk_length(const unsigned char* chunk):
1384 
1385 Get the length of the chunk's data. The total chunk length is this length + 12.
1386 
1387 void lodepng_chunk_type(char type[5], const unsigned char* chunk):
1388 unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type):
1389 
1390 Get the type of the chunk or compare if it's a certain type
1391 
1392 unsigned char lodepng_chunk_critical(const unsigned char* chunk):
1393 unsigned char lodepng_chunk_private(const unsigned char* chunk):
1394 unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk):
1395 
1396 Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are).
1397 Check if the chunk is private (public chunks are part of the standard, private ones not).
1398 Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical
1399 chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your
1400 program doesn't handle that type of unknown chunk.
1401 
1402 unsigned char* lodepng_chunk_data(unsigned char* chunk):
1403 const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk):
1404 
1405 Get a pointer to the start of the data of the chunk.
1406 
1407 unsigned lodepng_chunk_check_crc(const unsigned char* chunk):
1408 void lodepng_chunk_generate_crc(unsigned char* chunk):
1409 
1410 Check if the crc is correct or generate a correct one.
1411 
1412 unsigned char* lodepng_chunk_next(unsigned char* chunk):
1413 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk):
1414 
1415 Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these
1416 functions do no boundary checking of the allocated data whatsoever, so make sure there is enough
1417 data available in the buffer to be able to go to the next chunk.
1418 
1419 unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk):
1420 unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length,
1421  const char* type, const unsigned char* data):
1422 
1423 These functions are used to create new chunks that are appended to the data in *out that has
1424 length *outlength. The append function appends an existing chunk to the new data. The create
1425 function creates a new chunk with the given parameters and appends it. Type is the 4-letter
1426 name of the chunk.
1427 
1428 8.2. chunks in info_png
1429 -----------------------
1430 
1431 The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3
1432 buffers (each with size) to contain 3 types of unknown chunks:
1433 the ones that come before the PLTE chunk, the ones that come between the PLTE
1434 and the IDAT chunks, and the ones that come after the IDAT chunks.
1435 It's necessary to make the distionction between these 3 cases because the PNG
1436 standard forces to keep the ordering of unknown chunks compared to the critical
1437 chunks, but does not force any other ordering rules.
1438 
1439 info_png.unknown_chunks_data[0] is the chunks before PLTE
1440 info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT
1441 info_png.unknown_chunks_data[2] is the chunks after IDAT
1442 
1443 The chunks in these 3 buffers can be iterated through and read by using the same
1444 way described in the previous subchapter.
1445 
1446 When using the decoder to decode a PNG, you can make it store all unknown chunks
1447 if you set the option settings.remember_unknown_chunks to 1. By default, this
1448 option is off (0).
1449 
1450 The encoder will always encode unknown chunks that are stored in the info_png.
1451 If you need it to add a particular chunk that isn't known by LodePNG, you can
1452 use lodepng_chunk_append or lodepng_chunk_create to the chunk data in
1453 info_png.unknown_chunks_data[x].
1454 
1455 Chunks that are known by LodePNG should not be added in that way. E.g. to make
1456 LodePNG add a bKGD chunk, set background_defined to true and add the correct
1457 parameters there instead.
1458 
1459 
1460 9. compiler support
1461 -------------------
1462 
1463 No libraries other than the current standard C library are needed to compile
1464 LodePNG. For the C++ version, only the standard C++ library is needed on top.
1465 Add the files lodepng.c(pp) and lodepng.h to your project, include
1466 lodepng.h where needed, and your program can read/write PNG files.
1467 
1468 It is compatible with C90 and up, and C++03 and up.
1469 
1470 If performance is important, use optimization when compiling! For both the
1471 encoder and decoder, this makes a large difference.
1472 
1473 Make sure that LodePNG is compiled with the same compiler of the same version
1474 and with the same settings as the rest of the program, or the interfaces with
1475 std::vectors and std::strings in C++ can be incompatible.
1476 
1477 CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets.
1478 
1479 *) gcc and g++
1480 
1481 LodePNG is developed in gcc so this compiler is natively supported. It gives no
1482 warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++
1483 version 4.7.1 on Linux, 32-bit and 64-bit.
1484 
1485 *) Clang
1486 
1487 Fully supported and warning-free.
1488 
1489 *) Mingw
1490 
1491 The Mingw compiler (a port of gcc for Windows) should be fully supported by
1492 LodePNG.
1493 
1494 *) Visual Studio and Visual C++ Express Edition
1495 
1496 LodePNG should be warning-free with warning level W4. Two warnings were disabled
1497 with pragmas though: warning 4244 about implicit conversions, and warning 4996
1498 where it wants to use a non-standard function fopen_s instead of the standard C
1499 fopen.
1500 
1501 Visual Studio may want "stdafx.h" files to be included in each source file and
1502 give an error "unexpected end of file while looking for precompiled header".
1503 This is not standard C++ and will not be added to the stock LodePNG. You can
1504 disable it for lodepng.cpp only by right clicking it, Properties, C/C++,
1505 Precompiled Headers, and set it to Not Using Precompiled Headers there.
1506 
1507 NOTE: Modern versions of VS should be fully supported, but old versions, e.g.
1508 VS6, are not guaranteed to work.
1509 
1510 *) Compilers on Macintosh
1511 
1512 LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for
1513 C and C++.
1514 
1515 *) Other Compilers
1516 
1517 If you encounter problems on any compilers, feel free to let me know and I may
1518 try to fix it if the compiler is modern and standards complient.
1519 
1520 
1521 10. examples
1522 ------------
1523 
1524 This decoder example shows the most basic usage of LodePNG. More complex
1525 examples can be found on the LodePNG website.
1526 
1527 10.1. decoder C++ example
1528 -------------------------
1529 
1530 #include "lodepng.h"
1531 #include <iostream>
1532 
1533 int main(int argc, char *argv[])
1534 {
1535  const char* filename = argc > 1 ? argv[1] : "test.png";
1536 
1537  //load and decode
1538  std::vector<unsigned char> image;
1539  unsigned width, height;
1540  unsigned error = lodepng::decode(image, width, height, filename);
1541 
1542  //if there's an error, display it
1543  if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl;
1544 
1545  //the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ...
1546 }
1547 
1548 10.2. decoder C example
1549 -----------------------
1550 
1551 #include "lodepng.h"
1552 
1553 int main(int argc, char *argv[])
1554 {
1555  unsigned error;
1556  unsigned char* image;
1557  size_t width, height;
1558  const char* filename = argc > 1 ? argv[1] : "test.png";
1559 
1560  error = lodepng_decode32_file(&image, &width, &height, filename);
1561 
1562  if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error));
1563 
1564  / * use image here * /
1565 
1566  free(image);
1567  return 0;
1568 }
1569 
1570 11. state settings reference
1571 ----------------------------
1572 
1573 A quick reference of some settings to set on the LodePNGState
1574 
1575 For decoding:
1576 
1577 state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums
1578 state.decoder.zlibsettings.custom_...: use custom inflate function
1579 state.decoder.ignore_crc: ignore CRC checksums
1580 state.decoder.ignore_critical: ignore unknown critical chunks
1581 state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors
1582 state.decoder.color_convert: convert internal PNG color to chosen one
1583 state.decoder.read_text_chunks: whether to read in text metadata chunks
1584 state.decoder.remember_unknown_chunks: whether to read in unknown chunks
1585 state.info_raw.colortype: desired color type for decoded image
1586 state.info_raw.bitdepth: desired bit depth for decoded image
1587 state.info_raw....: more color settings, see struct LodePNGColorMode
1588 state.info_png....: no settings for decoder but ouput, see struct LodePNGInfo
1589 
1590 For encoding:
1591 
1592 state.encoder.zlibsettings.btype: disable compression by setting it to 0
1593 state.encoder.zlibsettings.use_lz77: use LZ77 in compression
1594 state.encoder.zlibsettings.windowsize: tweak LZ77 windowsize
1595 state.encoder.zlibsettings.minmatch: tweak min LZ77 length to match
1596 state.encoder.zlibsettings.nicematch: tweak LZ77 match where to stop searching
1597 state.encoder.zlibsettings.lazymatching: try one more LZ77 matching
1598 state.encoder.zlibsettings.custom_...: use custom deflate function
1599 state.encoder.auto_convert: choose optimal PNG color type, if 0 uses info_png
1600 state.encoder.filter_palette_zero: PNG filter strategy for palette
1601 state.encoder.filter_strategy: PNG filter strategy to encode with
1602 state.encoder.force_palette: add palette even if not encoding to one
1603 state.encoder.add_id: add LodePNG identifier and version as a text chunk
1604 state.encoder.text_compression: use compressed text chunks for metadata
1605 state.info_raw.colortype: color type of raw input image you provide
1606 state.info_raw.bitdepth: bit depth of raw input image you provide
1607 state.info_raw: more color settings, see struct LodePNGColorMode
1608 state.info_png.color.colortype: desired color type if auto_convert is false
1609 state.info_png.color.bitdepth: desired bit depth if auto_convert is false
1610 state.info_png.color....: more color settings, see struct LodePNGColorMode
1611 state.info_png....: more PNG related settings, see struct LodePNGInfo
1612 
1613 
1614 12. changes
1615 -----------
1616 
1617 The version number of LodePNG is the date of the change given in the format
1618 yyyymmdd.
1619 
1620 Some changes aren't backwards compatible. Those are indicated with a (!)
1621 symbol.
1622 
1623 *) 14 jan 2018: allow optionally ignoring a few more recoverable errors
1624 *) 17 sep 2017: fix memory leak for some encoder input error cases
1625 *) 27 nov 2016: grey+alpha auto color model detection bugfix
1626 *) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort).
1627 *) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within
1628  the limits of pure C90).
1629 *) 08 dec 2015: Made load_file function return error if file can't be opened.
1630 *) 24 okt 2015: Bugfix with decoding to palette output.
1631 *) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding.
1632 *) 23 aug 2014: Reduced needless memory usage of decoder.
1633 *) 28 jun 2014: Removed fix_png setting, always support palette OOB for
1634  simplicity. Made ColorProfile public.
1635 *) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization.
1636 *) 22 dec 2013: Power of two windowsize required for optimization.
1637 *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key.
1638 *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png).
1639 *) 11 mar 2013 (!): Bugfix with custom free. Changed from "my" to "lodepng_"
1640  prefix for the custom allocators and made it possible with a new #define to
1641  use custom ones in your project without needing to change lodepng's code.
1642 *) 28 jan 2013: Bugfix with color key.
1643 *) 27 okt 2012: Tweaks in text chunk keyword length error handling.
1644 *) 8 okt 2012 (!): Added new filter strategy (entropy) and new auto color mode.
1645  (no palette). Better deflate tree encoding. New compression tweak settings.
1646  Faster color conversions while decoding. Some internal cleanups.
1647 *) 23 sep 2012: Reduced warnings in Visual Studio a little bit.
1648 *) 1 sep 2012 (!): Removed #define's for giving custom (de)compression functions
1649  and made it work with function pointers instead.
1650 *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc
1651  and free functions and toggle #defines from compiler flags. Small fixes.
1652 *) 6 may 2012 (!): Made plugging in custom zlib/deflate functions more flexible.
1653 *) 22 apr 2012 (!): Made interface more consistent, renaming a lot. Removed
1654  redundant C++ codec classes. Reduced amount of structs. Everything changed,
1655  but it is cleaner now imho and functionality remains the same. Also fixed
1656  several bugs and shrunk the implementation code. Made new samples.
1657 *) 6 nov 2011 (!): By default, the encoder now automatically chooses the best
1658  PNG color model and bit depth, based on the amount and type of colors of the
1659  raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color.
1660 *) 9 okt 2011: simpler hash chain implementation for the encoder.
1661 *) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching.
1662 *) 23 aug 2011: tweaked the zlib compression parameters after benchmarking.
1663  A bug with the PNG filtertype heuristic was fixed, so that it chooses much
1664  better ones (it's quite significant). A setting to do an experimental, slow,
1665  brute force search for PNG filter types is added.
1666 *) 17 aug 2011 (!): changed some C zlib related function names.
1667 *) 16 aug 2011: made the code less wide (max 120 characters per line).
1668 *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors.
1669 *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled.
1670 *) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman
1671  to optimize long sequences of zeros.
1672 *) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and
1673  LodePNG_InfoColor_canHaveAlpha functions for convenience.
1674 *) 7 nov 2010: added LodePNG_error_text function to get error code description.
1675 *) 30 okt 2010: made decoding slightly faster
1676 *) 26 okt 2010: (!) changed some C function and struct names (more consistent).
1677  Reorganized the documentation and the declaration order in the header.
1678 *) 08 aug 2010: only changed some comments and external samples.
1679 *) 05 jul 2010: fixed bug thanks to warnings in the new gcc version.
1680 *) 14 mar 2010: fixed bug where too much memory was allocated for char buffers.
1681 *) 02 sep 2008: fixed bug where it could create empty tree that linux apps could
1682  read by ignoring the problem but windows apps couldn't.
1683 *) 06 jun 2008: added more error checks for out of memory cases.
1684 *) 26 apr 2008: added a few more checks here and there to ensure more safety.
1685 *) 06 mar 2008: crash with encoding of strings fixed
1686 *) 02 feb 2008: support for international text chunks added (iTXt)
1687 *) 23 jan 2008: small cleanups, and #defines to divide code in sections
1688 *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor.
1689 *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder.
1690 *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added
1691  Also various fixes, such as in the deflate and the padding bits code.
1692 *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved
1693  filtering code of encoder.
1694 *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A
1695  C++ wrapper around this provides an interface almost identical to before.
1696  Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code
1697  are together in these files but it works both for C and C++ compilers.
1698 *) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks
1699 *) 30 aug 2007: bug fixed which makes this Borland C++ compatible
1700 *) 09 aug 2007: some VS2005 warnings removed again
1701 *) 21 jul 2007: deflate code placed in new namespace separate from zlib code
1702 *) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images
1703 *) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing
1704  invalid std::vector element [0] fixed, and level 3 and 4 warnings removed
1705 *) 02 jun 2007: made the encoder add a tag with version by default
1706 *) 27 may 2007: zlib and png code separated (but still in the same file),
1707  simple encoder/decoder functions added for more simple usage cases
1708 *) 19 may 2007: minor fixes, some code cleaning, new error added (error 69),
1709  moved some examples from here to lodepng_examples.cpp
1710 *) 12 may 2007: palette decoding bug fixed
1711 *) 24 apr 2007: changed the license from BSD to the zlib license
1712 *) 11 mar 2007: very simple addition: ability to encode bKGD chunks.
1713 *) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding
1714  palettized PNG images. Plus little interface change with palette and texts.
1715 *) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes.
1716  Fixed a bug where the end code of a block had length 0 in the Huffman tree.
1717 *) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented
1718  and supported by the encoder, resulting in smaller PNGs at the output.
1719 *) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone.
1720 *) 24 jan 2007: gave encoder an error interface. Added color conversion from any
1721  greyscale type to 8-bit greyscale with or without alpha.
1722 *) 21 jan 2007: (!) Totally changed the interface. It allows more color types
1723  to convert to and is more uniform. See the manual for how it works now.
1724 *) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days:
1725  encode/decode custom tEXt chunks, separate classes for zlib & deflate, and
1726  at last made the decoder give errors for incorrect Adler32 or Crc.
1727 *) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel.
1728 *) 29 dec 2006: Added support for encoding images without alpha channel, and
1729  cleaned out code as well as making certain parts faster.
1730 *) 28 dec 2006: Added "Settings" to the encoder.
1731 *) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now.
1732  Removed some code duplication in the decoder. Fixed little bug in an example.
1733 *) 09 dec 2006: (!) Placed output parameters of public functions as first parameter.
1734  Fixed a bug of the decoder with 16-bit per color.
1735 *) 15 okt 2006: Changed documentation structure
1736 *) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the
1737  given image buffer, however for now it's not compressed.
1738 *) 08 sep 2006: (!) Changed to interface with a Decoder class
1739 *) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different
1740  way. Renamed decodePNG to decodePNGGeneric.
1741 *) 29 jul 2006: (!) Changed the interface: image info is now returned as a
1742  struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy.
1743 *) 28 jul 2006: Cleaned the code and added new error checks.
1744  Corrected terminology "deflate" into "inflate".
1745 *) 23 jun 2006: Added SDL example in the documentation in the header, this
1746  example allows easy debugging by displaying the PNG and its transparency.
1747 *) 22 jun 2006: (!) Changed way to obtain error value. Added
1748  loadFile function for convenience. Made decodePNG32 faster.
1749 *) 21 jun 2006: (!) Changed type of info vector to unsigned.
1750  Changed position of palette in info vector. Fixed an important bug that
1751  happened on PNGs with an uncompressed block.
1752 *) 16 jun 2006: Internally changed unsigned into unsigned where
1753  needed, and performed some optimizations.
1754 *) 07 jun 2006: (!) Renamed functions to decodePNG and placed them
1755  in LodePNG namespace. Changed the order of the parameters. Rewrote the
1756  documentation in the header. Renamed files to lodepng.cpp and lodepng.h
1757 *) 22 apr 2006: Optimized and improved some code
1758 *) 07 sep 2005: (!) Changed to std::vector interface
1759 *) 12 aug 2005: Initial release (C++, decoder only)
1760 
1761 
1762 13. contact information
1763 -----------------------
1764 
1765 Feel free to contact me with suggestions, problems, comments, ... concerning
1766 LodePNG. If you encounter a PNG image that doesn't work properly with this
1767 decoder, feel free to send it and I'll use it to find and fix the problem.
1768 
1769 My email address is (puzzle the account and domain together with an @ symbol):
1770 Domain: gmail dot com.
1771 Account: lode dot vandevenne.
1772 
1773 
1774 Copyright (c) 2005-2017 Lode Vandevenne
1775 */
unsigned second
Definition: lodepng.h:409
unsigned lodepng_get_bpp(const LodePNGColorMode *info)
Definition: lodepng.c:2671
unsigned key_g
Definition: lodepng.h:360
unsigned day
Definition: lodepng.h:406
LodePNGColorMode info_raw
Definition: lodepng.h:640
unsigned text_compression
Definition: lodepng.h:622
unsigned char lodepng_chunk_safetocopy(const unsigned char *chunk)
Definition: lodepng.c:2455
void lodepng_color_mode_cleanup(LodePNGColorMode *info)
Definition: lodepng.c:2599
unsigned lodepng_get_color_profile(LodePNGColorProfile *profile, const unsigned char *image, unsigned w, unsigned h, const LodePNGColorMode *mode_in)
Definition: lodepng.c:3575
unsigned lodepng_auto_choose_color(LodePNGColorMode *mode_out, const unsigned char *image, unsigned w, unsigned h, const LodePNGColorMode *mode_in)
Definition: lodepng.c:3771
unsigned lodepng_inflate(unsigned char **out, size_t *outsize, const unsigned char *in, size_t insize, const LodePNGDecompressSettings *settings)
Definition: lodepng.c:1289
Definition: lodepng.h:103
char ** text_strings
Definition: lodepng.h:454
unsigned bitdepth
Definition: lodepng.h:329
unsigned ignore_crc
Definition: lodepng.h:531
unsigned char * palette
Definition: lodepng.h:344
unsigned char lodepng_chunk_private(const unsigned char *chunk)
Definition: lodepng.c:2450
unsigned lodepng_info_copy(LodePNGInfo *dest, const LodePNGInfo *source)
Definition: lodepng.c:2960
unsigned lodepng_chunk_create(unsigned char **out, size_t *outlength, unsigned length, const char *type, const unsigned char *data)
Definition: lodepng.c:2518
struct LodePNGColorProfile LodePNGColorProfile
char ** itext_keys
Definition: lodepng.h:462
Definition: lodepng.h:569
struct LodePNGDecoderSettings LodePNGDecoderSettings
struct LodePNGColorMode LodePNGColorMode
unsigned background_g
Definition: lodepng.h:436
unsigned lodepng_save_file(const unsigned char *buffer, size_t buffersize, const char *filename)
Definition: lodepng.c:406
Definition: lodepng.h:632
const unsigned char * predefined_filters
Definition: lodepng.h:613
unsigned phys_y
Definition: lodepng.h:474
unsigned lodepng_convert(unsigned char *out, const unsigned char *in, const LodePNGColorMode *mode_out, const LodePNGColorMode *mode_in, unsigned w, unsigned h)
Definition: lodepng.c:3465
unsigned lodepng_deflate(unsigned char **out, size_t *outsize, const unsigned char *in, size_t insize, const LodePNGCompressSettings *settings)
Definition: lodepng.c:2064
Definition: lodepng.h:557
unsigned interlace_method
Definition: lodepng.h:419
unsigned short key_b
Definition: lodepng.h:575
Definition: lodepng.h:554
unsigned key_r
Definition: lodepng.h:359
unsigned lodepng_encode_file(const char *filename, const unsigned char *image, unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth)
Definition: lodepng.c:5884
unsigned read_text_chunks
Definition: lodepng.h:538
void lodepng_info_init(LodePNGInfo *info)
Definition: lodepng.c:2929
Definition: lodepng.h:101
const LodePNGCompressSettings lodepng_default_compress_settings
Definition: lodepng.c:2294
size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode *color)
Definition: lodepng.c:2714
size_t itext_num
Definition: lodepng.h:461
unsigned lodepng_is_palette_type(const LodePNGColorMode *info)
Definition: lodepng.c:2692
unsigned lodepng_decode(unsigned char **out, unsigned *w, unsigned *h, LodePNGState *state, const unsigned char *in, size_t insize)
Definition: lodepng.c:4745
unsigned char lodepng_chunk_type_equals(const unsigned char *chunk, const char *type)
Definition: lodepng.c:2439
unsigned background_defined
Definition: lodepng.h:434
unsigned add_id
Definition: lodepng.h:620
unsigned lodepng_decode24(unsigned char **out, unsigned *w, unsigned *h, const unsigned char *in, size_t insize)
Definition: lodepng.c:4808
unsigned lodepng_encode(unsigned char **out, size_t *outsize, const unsigned char *image, unsigned w, unsigned h, LodePNGState *state)
Definition: lodepng.c:5664
unsigned filter_palette_zero
Definition: lodepng.h:605
void lodepng_chunk_generate_crc(unsigned char *chunk)
Definition: lodepng.c:2480
LodePNGDecompressSettings zlibsettings
Definition: lodepng.h:528
void lodepng_color_profile_init(LodePNGColorProfile *profile)
Definition: lodepng.c:3541
unsigned lodepng_encode24_file(const char *filename, const unsigned char *image, unsigned w, unsigned h)
Definition: lodepng.c:5900
unsigned lodepng_encode32(unsigned char **out, size_t *outsize, const unsigned char *image, unsigned w, unsigned h)
Definition: lodepng.c:5873
unsigned lodepng_is_greyscale_type(const LodePNGColorMode *info)
Definition: lodepng.c:2682
LodePNGColorType colortype
Definition: lodepng.h:328
unsigned background_r
Definition: lodepng.h:435
char str[6]
Definition: panvswr2.c:1674
void lodepng_color_mode_init(LodePNGColorMode *info)
Definition: lodepng.c:2589
char ** itext_strings
Definition: lodepng.h:465
unsigned ignore_adler32
Definition: lodepng.h:265
const char * LODEPNG_VERSION_STRING
Definition: lodepng.c:48
Definition: lodepng.h:564
void lodepng_state_copy(LodePNGState *dest, const LodePNGState *source)
Definition: lodepng.c:4873
unsigned nicematch
Definition: lodepng.h:298
unsigned char lodepng_chunk_ancillary(const unsigned char *chunk)
Definition: lodepng.c:2445
void lodepng_clear_text(LodePNGInfo *info)
Definition: lodepng.c:2814
void lodepng_state_cleanup(LodePNGState *state)
Definition: lodepng.c:4867
void lodepng_info_cleanup(LodePNGInfo *info)
Definition: lodepng.c:2949
const void * custom_context
Definition: lodepng.h:278
unsigned background_b
Definition: lodepng.h:437
unsigned phys_unit
Definition: lodepng.h:475
struct LodePNGInfo LodePNGInfo
unsigned short key_g
Definition: lodepng.h:574
unsigned lodepng_decode_file(unsigned char **out, unsigned *w, unsigned *h, const char *filename, LodePNGColorType colortype, unsigned bitdepth)
Definition: lodepng.c:4814
unsigned ignore_end
Definition: lodepng.h:533
Definition: lodepng.h:562
unsigned lodepng_has_palette_alpha(const LodePNGColorMode *info)
Definition: lodepng.c:2697
unsigned color_convert
Definition: lodepng.h:535
unsigned lodepng_get_channels(const LodePNGColorMode *info)
Definition: lodepng.c:2677
unsigned error
Definition: lodepng.h:642
unsigned lodepng_zlib_decompress(unsigned char **out, size_t *outsize, const unsigned char *in, size_t insize, const LodePNGDecompressSettings *settings)
Definition: lodepng.c:2132
void lodepng_clear_itext(LodePNGInfo *info)
Definition: lodepng.c:2886
Definition: lodepng.h:102
unsigned key
Definition: lodepng.h:572
unsigned lodepng_encode32_file(const char *filename, const unsigned char *image, unsigned w, unsigned h)
Definition: lodepng.c:5895
LodePNGInfo info_png
Definition: lodepng.h:641
unsigned compression_method
Definition: lodepng.h:417
LodePNGFilterStrategy
Definition: lodepng.h:549
unsigned lodepng_inspect(unsigned *w, unsigned *h, LodePNGState *state, const unsigned char *in, size_t insize)
Definition: lodepng.c:3911
unsigned lodepng_encode24(unsigned char **out, size_t *outsize, const unsigned char *image, unsigned w, unsigned h)
Definition: lodepng.c:5878
void lodepng_decoder_settings_init(LodePNGDecoderSettings *settings)
Definition: lodepng.c:4837
LodePNGTime time
Definition: lodepng.h:469
Definition: lodepng.h:402
Definition: lodepng.h:291
const unsigned char * lodepng_chunk_next_const(const unsigned char *chunk)
Definition: lodepng.c:2493
Definition: lodepng.h:325
unsigned lodepng_crc32(const unsigned char *buf, size_t len)
Definition: lodepng.c:2365
unsigned lodepng_decode_memory(unsigned char **out, unsigned *w, unsigned *h, const unsigned char *in, size_t insize, LodePNGColorType colortype, unsigned bitdepth)
Definition: lodepng.c:4790
unsigned lodepng_chunk_append(unsigned char **out, size_t *outlength, const unsigned char *chunk)
Definition: lodepng.c:2499
Definition: lodepng.h:414
uint32_t color
Definition: keyboard.c:29
LodePNGCompressSettings zlibsettings
Definition: lodepng.h:597
void lodepng_compress_settings_init(LodePNGCompressSettings *settings)
Definition: lodepng.c:2279
unsigned lodepng_add_text(LodePNGInfo *info, const char *key, const char *str)
Definition: lodepng.c:2819
struct LodePNGEncoderSettings LodePNGEncoderSettings
unsigned ignore_critical
Definition: lodepng.h:532
unsigned char * lodepng_chunk_next(unsigned char *chunk)
Definition: lodepng.c:2487
unsigned lodepng_encode_memory(unsigned char **out, size_t *outsize, const unsigned char *image, unsigned w, unsigned h, LodePNGColorType colortype, unsigned bitdepth)
Definition: lodepng.c:5857
unsigned lodepng_palette_add(LodePNGColorMode *info, unsigned char r, unsigned char g, unsigned char b, unsigned char a)
Definition: lodepng.c:2650
unsigned phys_defined
Definition: lodepng.h:472
Definition: lodepng.h:100
const LodePNGDecompressSettings lodepng_default_decompress_settings
Definition: lodepng.c:2310
unsigned month
Definition: lodepng.h:405
void lodepng_palette_clear(LodePNGColorMode *info)
Definition: lodepng.c:2643
const void * custom_context
Definition: lodepng.h:312
unsigned phys_x
Definition: lodepng.h:473
unsigned year
Definition: lodepng.h:404
unsigned lodepng_decode24_file(unsigned char **out, unsigned *w, unsigned *h, const char *filename)
Definition: lodepng.c:4831
unsigned char * lodepng_chunk_data(unsigned char *chunk)
Definition: lodepng.c:2460
void lodepng_encoder_settings_init(LodePNGEncoderSettings *settings)
Definition: lodepng.c:5906
char ** itext_langtags
Definition: lodepng.h:463
Definition: lodepng.h:552
unsigned lodepng_load_file(unsigned char **out, size_t *outsize, const char *filename)
Definition: lodepng.c:393
unsigned key_defined
Definition: lodepng.h:358
LodePNGFilterStrategy filter_strategy
Definition: lodepng.h:608
Definition: lodepng.h:595
unsigned windowsize
Definition: lodepng.h:296
Definition: lodepng.h:262
void settings()
Definition: emrtc.c:457
unsigned time_defined
Definition: lodepng.h:468
LodePNGColorType
Definition: lodepng.h:97
unsigned lodepng_add_itext(LodePNGInfo *info, const char *key, const char *langtag, const char *transkey, const char *str)
Definition: lodepng.c:2891
unsigned lodepng_can_have_alpha(const LodePNGColorMode *info)
Definition: lodepng.c:2707
const char * lodepng_error_text(unsigned code)
Definition: lodepng.c:5928
void lodepng_state_init(LodePNGState *state)
Definition: lodepng.c:4854
unsigned lazymatching
Definition: lodepng.h:299
unsigned short key_r
Definition: lodepng.h:573
char ** itext_transkeys
Definition: lodepng.h:464
unsigned btype
Definition: lodepng.h:294
LodePNGDecoderSettings decoder
Definition: lodepng.h:635
unsigned force_palette
Definition: lodepng.h:617
void lodepng_chunk_type(char type[5], const unsigned char *chunk)
Definition: lodepng.c:2432
unsigned hour
Definition: lodepng.h:407
LodePNGColorMode color
Definition: lodepng.h:420
unsigned use_lz77
Definition: lodepng.h:295
char ** text_keys
Definition: lodepng.h:453
unsigned key_b
Definition: lodepng.h:361
unsigned colored
Definition: lodepng.h:571
unsigned lodepng_decode32_file(unsigned char **out, unsigned *w, unsigned *h, const char *filename)
Definition: lodepng.c:4826
LodePNGEncoderSettings encoder
Definition: lodepng.h:638
unsigned bits
Definition: lodepng.h:579
Definition: lodepng.h:526
unsigned minute
Definition: lodepng.h:408
unsigned lodepng_is_alpha_type(const LodePNGColorMode *info)
Definition: lodepng.c:2687
unsigned alpha
Definition: lodepng.h:576
unsigned lodepng_color_mode_copy(LodePNGColorMode *dest, const LodePNGColorMode *source)
Definition: lodepng.c:2604
const unsigned char * lodepng_chunk_data_const(const unsigned char *chunk)
Definition: lodepng.c:2465
unsigned auto_convert
Definition: lodepng.h:599
unsigned numcolors
Definition: lodepng.h:577
Definition: lodepng.h:99
unsigned lodepng_decode32(unsigned char **out, unsigned *w, unsigned *h, const unsigned char *in, size_t insize)
Definition: lodepng.c:4803
unsigned filter_method
Definition: lodepng.h:418
size_t palettesize
Definition: lodepng.h:345
unsigned minmatch
Definition: lodepng.h:297
unsigned lodepng_zlib_compress(unsigned char **out, size_t *outsize, const unsigned char *in, size_t insize, const LodePNGCompressSettings *settings)
Definition: lodepng.c:2194
void lodepng_decompress_settings_init(LodePNGDecompressSettings *settings)
Definition: lodepng.c:2301
struct LodePNGTime LodePNGTime
unsigned remember_unknown_chunks
Definition: lodepng.h:540
static char buf[64]
Definition: panvswr2.c:111
unsigned lodepng_huffman_code_lengths(unsigned *lengths, const unsigned *frequencies, size_t numcodes, unsigned maxbitlen)
Definition: lodepng.c:795
unsigned lodepng_chunk_length(const unsigned char *chunk)
Definition: lodepng.c:2427
size_t text_num
Definition: lodepng.h:452
unsigned lodepng_chunk_check_crc(const unsigned char *chunk)
Definition: lodepng.c:2470
struct LodePNGState LodePNGState