diff options
Diffstat (limited to 'src/zopflipng/lodepng/lodepng.h')
| -rw-r--r-- | src/zopflipng/lodepng/lodepng.h | 759 |
1 files changed, 510 insertions, 249 deletions
diff --git a/src/zopflipng/lodepng/lodepng.h b/src/zopflipng/lodepng/lodepng.h index c497a5c..6801cb7 100644 --- a/src/zopflipng/lodepng/lodepng.h +++ b/src/zopflipng/lodepng/lodepng.h @@ -1,7 +1,7 @@ /* -LodePNG version 20131222 +LodePNG version 20201017 -Copyright (c) 2005-2013 Lode Vandevenne +Copyright (c) 2005-2020 Lode Vandevenne This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages @@ -28,10 +28,7 @@ freely, subject to the following restrictions: #include <string.h> /*for size_t*/ -#ifdef __cplusplus -#include <vector> -#include <string> -#endif /*__cplusplus*/ +extern const char* LODEPNG_VERSION_STRING; /* The following #defines are used to create code sections. They can be disabled @@ -39,42 +36,52 @@ to disable code sections, which can give faster compile time and smaller binary. The "NO_COMPILE" defines are designed to be used to pass as defines to the compiler command to disable them without modifying this header, e.g. -DLODEPNG_NO_COMPILE_ZLIB for gcc. +In addition to those below, you can also define LODEPNG_NO_COMPILE_CRC to +allow implementing a custom lodepng_crc32. */ /*deflate & zlib. If disabled, you must specify alternative zlib functions in the custom_zlib field of the compress and decompress settings*/ #ifndef LODEPNG_NO_COMPILE_ZLIB #define LODEPNG_COMPILE_ZLIB #endif + /*png encoder and png decoder*/ #ifndef LODEPNG_NO_COMPILE_PNG #define LODEPNG_COMPILE_PNG #endif + /*deflate&zlib decoder and png decoder*/ #ifndef LODEPNG_NO_COMPILE_DECODER #define LODEPNG_COMPILE_DECODER #endif + /*deflate&zlib encoder and png encoder*/ #ifndef LODEPNG_NO_COMPILE_ENCODER #define LODEPNG_COMPILE_ENCODER #endif + /*the optional built in harddisk file loading and saving functions*/ #ifndef LODEPNG_NO_COMPILE_DISK #define LODEPNG_COMPILE_DISK #endif + /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/ #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS #define LODEPNG_COMPILE_ANCILLARY_CHUNKS #endif + /*ability to convert error numerical codes to English text string*/ #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT #define LODEPNG_COMPILE_ERROR_TEXT #endif + /*Compile the default allocators (C's free, malloc and realloc). If you disable this, you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your source files with custom allocators.*/ #ifndef LODEPNG_NO_COMPILE_ALLOCATORS #define LODEPNG_COMPILE_ALLOCATORS #endif + /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/ #ifdef __cplusplus #ifndef LODEPNG_NO_COMPILE_CPP @@ -82,15 +89,25 @@ source files with custom allocators.*/ #endif #endif +#ifdef LODEPNG_COMPILE_CPP +#include <vector> +#include <string> +#endif /*LODEPNG_COMPILE_CPP*/ + #ifdef LODEPNG_COMPILE_PNG -/*The PNG color types (also used for raw).*/ -typedef enum LodePNGColorType -{ - LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/ +/*The PNG color types (also used for raw image).*/ +typedef enum LodePNGColorType { + LCT_GREY = 0, /*grayscale: 1,2,4,8,16 bit*/ LCT_RGB = 2, /*RGB: 8,16 bit*/ LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/ - LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/ - LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/ + LCT_GREY_ALPHA = 4, /*grayscale with alpha: 8,16 bit*/ + LCT_RGBA = 6, /*RGB with alpha: 8,16 bit*/ + /*LCT_MAX_OCTET_VALUE lets the compiler allow this enum to represent any invalid + byte value from 0 to 255 that could be present in an invalid PNG file header. Do + not use, compare with or set the name LCT_MAX_OCTET_VALUE, instead either use + the valid color type names above, or numeric values like 1 or 7 when checking for + particular disallowed color type byte values, or cast to integer to print it.*/ + LCT_MAX_OCTET_VALUE = 255 } LodePNGColorType; #ifdef LODEPNG_COMPILE_DECODER @@ -192,10 +209,10 @@ unsigned lodepng_encode24_file(const char* filename, #ifdef LODEPNG_COMPILE_CPP -namespace lodepng -{ +namespace lodepng { #ifdef LODEPNG_COMPILE_DECODER -/*Same as lodepng_decode_memory, but decodes to an std::vector.*/ +/*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype +is the format to output the pixels to. Default is RGBA 8-bit per channel.*/ unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const unsigned char* in, size_t insize, LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); @@ -210,11 +227,12 @@ Same as the other decode functions, but instead takes a filename as input. unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, const std::string& filename, LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); -#endif //LODEPNG_COMPILE_DISK -#endif //LODEPNG_COMPILE_DECODER +#endif /* LODEPNG_COMPILE_DISK */ +#endif /* LODEPNG_COMPILE_DECODER */ #ifdef LODEPNG_COMPILE_ENCODER -/*Same as lodepng_encode_memory, but encodes to an std::vector.*/ +/*Same as lodepng_encode_memory, but encodes to an std::vector. colortype +is that of the raw input data. The output PNG color type will be auto chosen.*/ unsigned encode(std::vector<unsigned char>& out, const unsigned char* in, unsigned w, unsigned h, LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); @@ -233,9 +251,9 @@ unsigned encode(const std::string& filename, unsigned encode(const std::string& filename, const std::vector<unsigned char>& in, unsigned w, unsigned h, LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); -#endif //LODEPNG_COMPILE_DISK -#endif //LODEPNG_COMPILE_ENCODER -} //namespace lodepng +#endif /* LODEPNG_COMPILE_DISK */ +#endif /* LODEPNG_COMPILE_ENCODER */ +} /* namespace lodepng */ #endif /*LODEPNG_COMPILE_CPP*/ #endif /*LODEPNG_COMPILE_PNG*/ @@ -247,17 +265,26 @@ const char* lodepng_error_text(unsigned code); #ifdef LODEPNG_COMPILE_DECODER /*Settings for zlib decompression*/ typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; -struct LodePNGDecompressSettings -{ +struct LodePNGDecompressSettings { + /* Check LodePNGDecoderSettings for more ignorable errors such as ignore_crc */ unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ + unsigned ignore_nlen; /*ignore complement of len checksum in uncompressed blocks*/ - /*use custom zlib decoder instead of built in one (default: null)*/ + /*Maximum decompressed size, beyond this the decoder may (and is encouraged to) stop decoding, + return an error, output a data size > max_output_size and all the data up to that point. This is + not hard limit nor a guarantee, but can prevent excessive memory usage. This setting is + ignored by the PNG decoder, but is used by the deflate/zlib decoder and can be used by custom ones. + Set to 0 to impose no limit (the default).*/ + size_t max_output_size; + + /*use custom zlib decoder instead of built in one (default: null). + Should return 0 if success, any non-0 if error (numeric value not exposed).*/ unsigned (*custom_zlib)(unsigned char**, size_t*, const unsigned char*, size_t, const LodePNGDecompressSettings*); /*use custom deflate decoder instead of built in one (default: null) - if custom_zlib is used, custom_deflate is ignored since only the built in - zlib function will call custom_deflate*/ + if custom_zlib is not null, custom_inflate is ignored (the zlib format uses deflate). + Should return 0 if success, any non-0 if error (numeric value not exposed).*/ unsigned (*custom_inflate)(unsigned char**, size_t*, const unsigned char*, size_t, const LodePNGDecompressSettings*); @@ -275,13 +302,12 @@ Settings for zlib compression. Tweaking these settings tweaks the balance between speed and compression ratio. */ typedef struct LodePNGCompressSettings LodePNGCompressSettings; -struct LodePNGCompressSettings /*deflate = compress*/ -{ +struct LodePNGCompressSettings /*deflate = compress*/ { /*LZ77 related settings*/ unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/ unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ - unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Typical value: 2048.*/ - unsigned minmatch; /*mininum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ + unsigned windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/ + unsigned minmatch; /*minimum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ unsigned nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/ unsigned lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ @@ -309,8 +335,7 @@ Color mode of an image. Contains all information required to decode the pixel bits to RGBA colors. This information is the same as used in the PNG file format, and is used both for PNG and raw image data in LodePNG. */ -typedef struct LodePNGColorMode -{ +typedef struct LodePNGColorMode { /*header (IHDR)*/ LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/ unsigned bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ @@ -319,23 +344,25 @@ typedef struct LodePNGColorMode palette (PLTE and tRNS) Dynamically allocated with the colors of the palette, including alpha. - When encoding a PNG, to store your colors in the palette of the LodePNGColorMode, first use - lodepng_palette_clear, then for each color use lodepng_palette_add. - If you encode an image without alpha with palette, don't forget to put value 255 in each A byte of the palette. + This field may not be allocated directly, use lodepng_color_mode_init first, + then lodepng_palette_add per color to correctly initialize it (to ensure size + of exactly 1024 bytes). + + The alpha channels must be set as well, set them to 255 for opaque images. When decoding, by default you can ignore this palette, since LodePNG already fills the palette colors in the pixels of the raw RGBA output. The palette is only supported for color type 3. */ - unsigned char* palette; /*palette in RGBARGBA... order. When allocated, must be either 0, or have size 1024*/ - size_t palettesize; /*palette size in number of colors (amount of bytes is 4 * palettesize)*/ + unsigned char* palette; /*palette in RGBARGBA... order. Must be either 0, or when allocated must have 1024 bytes*/ + size_t palettesize; /*palette size in number of colors (amount of used bytes is 4 * palettesize)*/ /* transparent color key (tRNS) This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit. - For greyscale PNGs, r, g and b will all 3 be set to the same. + For grayscale PNGs, r, g and b will all 3 be set to the same. When decoding, by default you can ignore this information, since LodePNG sets pixels with this key to transparent already in the raw RGBA output. @@ -343,7 +370,7 @@ typedef struct LodePNGColorMode The color key is only supported for color types 0 and 2. */ unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ - unsigned key_r; /*red/greyscale component of color key*/ + unsigned key_r; /*red/grayscale component of color key*/ unsigned key_g; /*green component of color key*/ unsigned key_b; /*blue component of color key*/ } LodePNGColorMode; @@ -353,6 +380,8 @@ void lodepng_color_mode_init(LodePNGColorMode* info); void lodepng_color_mode_cleanup(LodePNGColorMode* info); /*return value is error code (0 means no error)*/ unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source); +/* Makes a temporary LodePNGColorMode that does not need cleanup (no palette) */ +LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth); void lodepng_palette_clear(LodePNGColorMode* info); /*add 1 color to the palette*/ @@ -364,7 +393,7 @@ unsigned lodepng_get_bpp(const LodePNGColorMode* info); /*get the amount of color channels used, based on colortype in the struct. If a palette is used, it counts as 1 channel.*/ unsigned lodepng_get_channels(const LodePNGColorMode* info); -/*is it a greyscale type? (only colortype 0 or 4)*/ +/*is it a grayscale type? (only colortype 0 or 4)*/ unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info); /*has it got an alpha channel? (only colortype 2 or 6)*/ unsigned lodepng_is_alpha_type(const LodePNGColorMode* info); @@ -386,8 +415,7 @@ size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* colo #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS /*The information of a Time chunk in PNG.*/ -typedef struct LodePNGTime -{ +typedef struct LodePNGTime { unsigned year; /*2 bytes used (0-65535)*/ unsigned month; /*1-12*/ unsigned day; /*1-31*/ @@ -398,52 +426,73 @@ typedef struct LodePNGTime #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ /*Information about the PNG image, except pixels, width and height.*/ -typedef struct LodePNGInfo -{ +typedef struct LodePNGInfo { /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ unsigned compression_method;/*compression method of the original file. Always 0.*/ unsigned filter_method; /*filter method of the original file*/ - unsigned interlace_method; /*interlace method of the original file*/ + unsigned interlace_method; /*interlace method of the original file: 0=none, 1=Adam7*/ LodePNGColorMode color; /*color type and bits, palette and transparency of the PNG file*/ #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS /* - suggested background color chunk (bKGD) - This color uses the same color mode as the PNG (except alpha channel), which can be 1-bit to 16-bit. + Suggested background color chunk (bKGD) + + This uses the same color mode and bit depth as the PNG (except no alpha channel), + with values truncated to the bit depth in the unsigned integer. + + For grayscale and palette PNGs, the value is stored in background_r. The values + in background_g and background_b are then unused. - For greyscale PNGs, r, g and b will all 3 be set to the same. When encoding - the encoder writes the red one. For palette PNGs: When decoding, the RGB value - will be stored, not a palette index. But when encoding, specify the index of - the palette in background_r, the other two are then ignored. + So when decoding, you may get these in a different color mode than the one you requested + for the raw pixels. - The decoder does not use this background color to edit the color of pixels. + When encoding with auto_convert, you must use the color model defined in info_png.color for + these values. The encoder normally ignores info_png.color when auto_convert is on, but will + use it to interpret these values (and convert copies of them to its chosen color model). + + When encoding, avoid setting this to an expensive color, such as a non-gray value + when the image is gray, or the compression will be worse since it will be forced to + write the PNG with a more expensive color mode (when auto_convert is on). + + The decoder does not use this background color to edit the color of pixels. This is a + completely optional metadata feature. */ unsigned background_defined; /*is a suggested background color given?*/ - unsigned background_r; /*red component of suggested background color*/ + unsigned background_r; /*red/gray/palette component of suggested background color*/ unsigned background_g; /*green component of suggested background color*/ unsigned background_b; /*blue component of suggested background color*/ /* - non-international text chunks (tEXt and zTXt) + Non-international text chunks (tEXt and zTXt) The char** arrays each contain num strings. The actual messages are in text_strings, while text_keys are keywords that give a short description what the actual text represents, e.g. Title, Author, Description, or anything else. - A keyword is minimum 1 character and maximum 79 characters long. It's - discouraged to use a single line length longer than 79 characters for texts. + All the string fields below including strings, keys, names and language tags are null terminated. + The PNG specification uses null characters for the keys, names and tags, and forbids null + characters to appear in the main text which is why we can use null termination everywhere here. + + A keyword is minimum 1 character and maximum 79 characters long (plus the + additional null terminator). It's discouraged to use a single line length + longer than 79 characters for texts. Don't allocate these text buffers yourself. Use the init/cleanup functions correctly and use lodepng_add_text and lodepng_clear_text. + + Standard text chunk keywords and strings are encoded using Latin-1. */ size_t text_num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/ char** text_keys; /*the keyword of a text chunk (e.g. "Comment")*/ char** text_strings; /*the actual text*/ /* - international text chunks (iTXt) + International text chunks (iTXt) Similar to the non-international text chunks, but with additional strings - "langtags" and "transkeys". + "langtags" and "transkeys", and the following text encodings are used: + keys: Latin-1, langtags: ASCII, transkeys and strings: UTF-8. + keys must be 1-79 characters (plus the additional null terminator), the other + strings are any length. */ size_t itext_num; /*the amount of international texts in this PNG*/ char** itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ @@ -462,11 +511,86 @@ typedef struct LodePNGInfo unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ /* - unknown chunks - There are 3 buffers, one for each position in the PNG where unknown chunks can appear - each buffer contains all unknown chunks for that position consecutively - The 3 buffers are the unknown chunks between certain critical chunks: - 0: IHDR-PLTE, 1: PLTE-IDAT, 2: IDAT-IEND + Color profile related chunks: gAMA, cHRM, sRGB, iCPP + + LodePNG does not apply any color conversions on pixels in the encoder or decoder and does not interpret these color + profile values. It merely passes on the information. If you wish to use color profiles and convert colors, please + use these values with a color management library. + + See the PNG, ICC and sRGB specifications for more information about the meaning of these values. + */ + + /* gAMA chunk: optional, overridden by sRGB or iCCP if those are present. */ + unsigned gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */ + unsigned gama_gamma; /* Gamma exponent times 100000 */ + + /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */ + unsigned chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */ + unsigned chrm_white_x; /* White Point x times 100000 */ + unsigned chrm_white_y; /* White Point y times 100000 */ + unsigned chrm_red_x; /* Red x times 100000 */ + unsigned chrm_red_y; /* Red y times 100000 */ + unsigned chrm_green_x; /* Green x times 100000 */ + unsigned chrm_green_y; /* Green y times 100000 */ + unsigned chrm_blue_x; /* Blue x times 100000 */ + unsigned chrm_blue_y; /* Blue y times 100000 */ + + /* + sRGB chunk: optional. May not appear at the same time as iCCP. + If gAMA is also present gAMA must contain value 45455. + If cHRM is also present cHRM must contain respectively 31270,32900,64000,33000,30000,60000,15000,6000. + */ + unsigned srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */ + unsigned srgb_intent; /* Rendering intent: 0=perceptual, 1=rel. colorimetric, 2=saturation, 3=abs. colorimetric */ + + /* + iCCP chunk: optional. May not appear at the same time as sRGB. + + LodePNG does not parse or use the ICC profile (except its color space header field for an edge case), a + separate library to handle the ICC data (not included in LodePNG) format is needed to use it for color + management and conversions. + + For encoding, if iCCP is present, gAMA and cHRM are recommended to be added as well with values that match the ICC + profile as closely as possible, if you wish to do this you should provide the correct values for gAMA and cHRM and + enable their '_defined' flags since LodePNG will not automatically compute them from the ICC profile. + + For encoding, the ICC profile is required by the PNG specification to be an "RGB" profile for non-gray + PNG color types and a "GRAY" profile for gray PNG color types. If you disable auto_convert, you must ensure + the ICC profile type matches your requested color type, else the encoder gives an error. If auto_convert is + enabled (the default), and the ICC profile is not a good match for the pixel data, this will result in an encoder + error if the pixel data has non-gray pixels for a GRAY profile, or a silent less-optimal compression of the pixel + data if the pixels could be encoded as grayscale but the ICC profile is RGB. + + To avoid this do not set an ICC profile in the image unless there is a good reason for it, and when doing so + make sure you compute it carefully to avoid the above problems. + */ + unsigned iccp_defined; /* Whether an iCCP chunk is present (0 = not present, 1 = present). */ + char* iccp_name; /* Null terminated string with profile name, 1-79 bytes */ + /* + The ICC profile in iccp_profile_size bytes. + Don't allocate this buffer yourself. Use the init/cleanup functions + correctly and use lodepng_set_icc and lodepng_clear_icc. + */ + unsigned char* iccp_profile; + unsigned iccp_profile_size; /* The size of iccp_profile in bytes */ + + /* End of color profile related chunks */ + + + /* + unknown chunks: chunks not known by LodePNG, passed on byte for byte. + + There are 3 buffers, one for each position in the PNG where unknown chunks can appear. + Each buffer contains all unknown chunks for that position consecutively. + The 3 positions are: + 0: between IHDR and PLTE, 1: between PLTE and IDAT, 2: between IDAT and IEND. + + For encoding, do not store critical chunks or known chunks that are enabled with a "_defined" flag + above in here, since the encoder will blindly follow this and could then encode an invalid PNG file + (such as one with two IHDR chunks or the disallowed combination of sRGB with iCCP). But do use + this if you wish to store an ancillary chunk that is not supported by LodePNG (such as sPLT or hIST), + or any non-standard PNG chunk. + Do not allocate or traverse this data yourself. Use the chunk traversing functions declared later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct. */ @@ -482,12 +606,16 @@ void lodepng_info_cleanup(LodePNGInfo* info); unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source); #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS -void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/ +void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ -void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag, const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/ +void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/ + +/*replaces if exists*/ +unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size); +void lodepng_clear_icc(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/ #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ /* @@ -496,40 +624,49 @@ LodePNGColorMode structs to describe the input and output color type. See the reference manual at the end of this header file to see which color conversions are supported. return value = LodePNG error code (0 if all went ok, an error if the conversion isn't supported) The out buffer must have size (w * h * bpp + 7) / 8, where bpp is the bits per pixel -of the output color type (lodepng_get_bpp) -The fix_png value works as described in struct LodePNGDecoderSettings. -Note: for 16-bit per channel colors, uses big endian format like PNG does. +of the output color type (lodepng_get_bpp). +For < 8 bpp images, there should not be padding bits at the end of scanlines. +For 16-bit per channel colors, uses big endian format like PNG does. +Return value is LodePNG error code */ unsigned lodepng_convert(unsigned char* out, const unsigned char* in, - LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in, - unsigned w, unsigned h, unsigned fix_png); + const LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in, + unsigned w, unsigned h); #ifdef LODEPNG_COMPILE_DECODER /* Settings for the decoder. This contains settings for the PNG and the Zlib decoder, but not the Info settings from the Info structs. */ -typedef struct LodePNGDecoderSettings -{ +typedef struct LodePNGDecoderSettings { LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ + /* Check LodePNGDecompressSettings for more ignorable errors such as ignore_adler32 */ unsigned ignore_crc; /*ignore CRC checksums*/ - /* - The fix_png setting, if 1, makes the decoder tolerant towards some PNG images - that do not correctly follow the PNG specification. This only supports errors - that are fixable, were found in images that are actually used on the web, and - are silently tolerated by other decoders as well. Currently only one such fix - is implemented: if a palette index is out of bounds given the palette size, - interpret it as opaque black. - By default this value is 0, which makes it stop with an error on such images. - */ - unsigned fix_png; + unsigned ignore_critical; /*ignore unknown critical chunks*/ + unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/ + /* TODO: make a system involving warnings with levels and a strict mode instead. Other potentially recoverable + errors: srgb rendering intent value, size of content of ancillary chunks, more than 79 characters for some + strings, placement/combination rules for ancillary chunks, crc of unknown chunks, allowed characters + in string keys, etc... */ + unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS unsigned read_text_chunks; /*if false but remember_unknown_chunks is true, they're stored in the unknown chunks*/ + /*store all bytes from unknown chunks in the LodePNGInfo (off by default, useful for a png editor)*/ unsigned remember_unknown_chunks; + + /* maximum size for decompressed text chunks. If a text chunk's text is larger than this, an error is returned, + unless reading text chunks is disabled or this limit is set higher or disabled. Set to 0 to allow any size. + By default it is a value that prevents unreasonably large strings from hogging memory. */ + size_t max_text_size; + + /* maximum size for compressed ICC chunks. If the ICC profile is larger than this, an error will be returned. Set to + 0 to allow any size. By default this is a value that prevents ICC profiles that would be much larger than any + legitimate profile could be to hog memory. */ + size_t max_icc_size; #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ } LodePNGDecoderSettings; @@ -538,11 +675,15 @@ void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); #ifdef LODEPNG_COMPILE_ENCODER /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ -typedef enum LodePNGFilterStrategy -{ +typedef enum LodePNGFilterStrategy { /*every filter at zero*/ - LFS_ZERO, - /*Use filter that gives minumum sum, as described in the official PNG filter heuristic.*/ + LFS_ZERO = 0, + /*every filter at 1, 2, 3 or 4 (paeth), unlike LFS_ZERO not a good choice, but for testing*/ + LFS_ONE = 1, + LFS_TWO = 2, + LFS_THREE = 3, + LFS_FOUR = 4, + /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/ LFS_MINSUM, /*Use the filter type that gives smallest Shannon entropy for this scanline. Depending on the image, this is better or worse than minsum.*/ @@ -556,46 +697,39 @@ typedef enum LodePNGFilterStrategy LFS_PREDEFINED } LodePNGFilterStrategy; -/*automatically use color type with less bits per pixel if losslessly possible. Default: LAC_AUTO*/ -typedef enum LodePNGAutoConvert -{ - LAC_NO, /*use color type user requested*/ - LAC_ALPHA, /*use color type user requested, but if only opaque pixels and RGBA or grey+alpha, use RGB or grey*/ - LAC_AUTO, /*use PNG color type that can losslessly represent the uncompressed image the smallest possible*/ - /* - like AUTO, but do not choose 1, 2 or 4 bit per pixel types. - sometimes a PNG image compresses worse if less than 8 bits per pixels. - */ - LAC_AUTO_NO_NIBBLES, - /* - like AUTO, but never choose palette color type. For small images, encoding - the palette may take more bytes than what is gained. Note that AUTO also - already prevents encoding the palette for extremely small images, but that may - not be sufficient because due to the compression it cannot predict when to - switch. - */ - LAC_AUTO_NO_PALETTE, - LAC_AUTO_NO_NIBBLES_NO_PALETTE -} LodePNGAutoConvert; - - -/* -Automatically chooses color type that gives smallest amount of bits in the -output image, e.g. grey if there are only greyscale pixels, palette if there -are less than 256 colors, ... -The auto_convert parameter allows limiting it to not use palette, ... -*/ -unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out, - const unsigned char* image, unsigned w, unsigned h, - const LodePNGColorMode* mode_in, - LodePNGAutoConvert auto_convert); +/*Gives characteristics about the integer RGBA colors of the image (count, alpha channel usage, bit depth, ...), +which helps decide which color model to use for encoding. +Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/ +typedef struct LodePNGColorStats { + unsigned colored; /*not grayscale*/ + unsigned key; /*image is not opaque and color key is possible instead of full alpha*/ + unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/ + unsigned short key_g; + unsigned short key_b; + unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/ + unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16 or allow_palette is disabled.*/ + unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order, only valid when numcolors is valid*/ + unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for grayscale only. 16 if 16-bit per channel required.*/ + size_t numpixels; + + /*user settings for computing/using the stats*/ + unsigned allow_palette; /*default 1. if 0, disallow choosing palette colortype in auto_choose_color, and don't count numcolors*/ + unsigned allow_greyscale; /*default 1. if 0, choose RGB or RGBA even if the image only has gray colors*/ +} LodePNGColorStats; + +void lodepng_color_stats_init(LodePNGColorStats* stats); + +/*Get a LodePNGColorStats of the image. The stats must already have been inited. +Returns error code (e.g. alloc fail) or 0 if ok.*/ +unsigned lodepng_compute_color_stats(LodePNGColorStats* stats, + const unsigned char* image, unsigned w, unsigned h, + const LodePNGColorMode* mode_in); /*Settings for the encoder.*/ -typedef struct LodePNGEncoderSettings -{ +typedef struct LodePNGEncoderSettings { LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ - LodePNGAutoConvert auto_convert; /*how to automatically choose output PNG color type, if at all*/ + unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/ /*If true, follows the official PNG heuristic: if the PNG uses a palette or lower than 8 bit depth, set all filters to zero. Otherwise use the filter_strategy. Note that to @@ -628,8 +762,7 @@ void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) /*The settings, state and information for extended encoding and decoding.*/ -typedef struct LodePNGState -{ +typedef struct LodePNGState { #ifdef LODEPNG_COMPILE_DECODER LodePNGDecoderSettings decoder; /*the decoding settings*/ #endif /*LODEPNG_COMPILE_DECODER*/ @@ -639,10 +772,6 @@ typedef struct LodePNGState LodePNGColorMode info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ LodePNGInfo info_png; /*info of the PNG image obtained after decoding*/ unsigned error; -#ifdef LODEPNG_COMPILE_CPP - //For the lodepng::State subclass. - virtual ~LodePNGState(){} -#endif } LodePNGState; /*init, cleanup and copy functions to use with this struct*/ @@ -662,7 +791,7 @@ unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, /* Read the PNG header, but not the actual data. This returns only the information -that is in the header chunk of the PNG, such as width, height and color type. The +that is in the IHDR chunk of the PNG, such as width, height and color type. The information is placed in the info_png field of the LodePNGState. */ unsigned lodepng_inspect(unsigned* w, unsigned* h, @@ -670,6 +799,20 @@ unsigned lodepng_inspect(unsigned* w, unsigned* h, const unsigned char* in, size_t insize); #endif /*LODEPNG_COMPILE_DECODER*/ +/* +Reads one metadata chunk (other than IHDR) of the PNG file and outputs what it +read in the state. Returns error code on failure. +Use lodepng_inspect first with a new state, then e.g. lodepng_chunk_find_const +to find the desired chunk type, and if non null use lodepng_inspect_chunk (with +chunk_pointer - start_of_file as pos). +Supports most metadata chunks from the PNG standard (gAMA, bKGD, tEXt, ...). +Ignores unsupported, unknown, non-metadata or IHDR chunks (without error). +Requirements: &in[pos] must point to start of a chunk, must use regular +lodepng_inspect first since format of most other chunks depends on IHDR, and if +there is a PLTE chunk, that one must be inspected before tRNS or bKGD. +*/ +unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos, + const unsigned char* in, size_t insize); #ifdef LODEPNG_COMPILE_ENCODER /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ @@ -683,14 +826,30 @@ The lodepng_chunk functions are normally not needed, except to traverse the unknown chunks stored in the LodePNGInfo struct, or add new ones to it. It also allows traversing the chunks of an encoded PNG file yourself. -PNG standard chunk naming conventions: -First byte: uppercase = critical, lowercase = ancillary -Second byte: uppercase = public, lowercase = private -Third byte: must be uppercase -Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy +The chunk pointer always points to the beginning of the chunk itself, that is +the first byte of the 4 length bytes. + +In the PNG file format, chunks have the following format: +-4 bytes length: length of the data of the chunk in bytes (chunk itself is 12 bytes longer) +-4 bytes chunk type (ASCII a-z,A-Z only, see below) +-length bytes of data (may be 0 bytes if length was 0) +-4 bytes of CRC, computed on chunk name + data + +The first chunk starts at the 8th byte of the PNG file, the entire rest of the file +exists out of concatenated chunks with the above format. + +PNG standard chunk ASCII naming conventions: +-First byte: uppercase = critical, lowercase = ancillary +-Second byte: uppercase = public, lowercase = private +-Third byte: must be uppercase +-Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy */ -/*get the length of the data of the chunk. Total chunk length has 12 bytes more.*/ +/* +Gets the length of the data of the chunk. Total chunk length has 12 bytes more. +There must be at least 4 bytes to read from. If the result value is too large, +it may be corrupt data. +*/ unsigned lodepng_chunk_length(const unsigned char* chunk); /*puts the 4-byte type in null terminated string*/ @@ -718,24 +877,38 @@ unsigned lodepng_chunk_check_crc(const unsigned char* chunk); /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ void lodepng_chunk_generate_crc(unsigned char* chunk); -/*iterate to next chunks. don't use on IEND chunk, as there is no next chunk then*/ -unsigned char* lodepng_chunk_next(unsigned char* chunk); -const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk); +/* +Iterate to next chunks, allows iterating through all chunks of the PNG file. +Input must be at the beginning of a chunk (result of a previous lodepng_chunk_next call, +or the 8th byte of a PNG file which always has the first chunk), or alternatively may +point to the first byte of the PNG file (which is not a chunk but the magic header, the +function will then skip over it and return the first real chunk). +Will output pointer to the start of the next chunk, or at or beyond end of the file if there +is no more chunk after this or possibly if the chunk is corrupt. +Start this process at the 8th byte of the PNG file. +In a non-corrupt PNG file, the last chunk should have name "IEND". +*/ +unsigned char* lodepng_chunk_next(unsigned char* chunk, unsigned char* end); +const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk, const unsigned char* end); + +/*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/ +unsigned char* lodepng_chunk_find(unsigned char* chunk, unsigned char* end, const char type[5]); +const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]); /* Appends chunk to the data in out. The given chunk should already have its chunk header. -The out variable and outlength are updated to reflect the new reallocated buffer. +The out variable and outsize are updated to reflect the new reallocated buffer. Returns error code (0 if it went ok) */ -unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk); +unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk); /* Appends new chunk to out. The chunk to append is given by giving its length, type and data separately. The type is a 4-letter string. -The out variable and outlength are updated to reflect the new reallocated buffer. +The out variable and outsize are updated to reflect the new reallocated buffer. Returne error code (0 if it went ok) */ -unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, +unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length, const char* type, const unsigned char* data); @@ -818,21 +991,19 @@ unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const #endif /*LODEPNG_COMPILE_DISK*/ #ifdef LODEPNG_COMPILE_CPP -//The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. -namespace lodepng -{ +/* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */ +namespace lodepng { #ifdef LODEPNG_COMPILE_PNG -class State : public LodePNGState -{ +class State : public LodePNGState { public: State(); State(const State& other); - virtual ~State(); + ~State(); State& operator=(const State& other); }; #ifdef LODEPNG_COMPILE_DECODER -//Same as other lodepng::decode, but using a State for more settings and information. +/* Same as other lodepng::decode, but using a State for more settings and information. */ unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, State& state, const unsigned char* in, size_t insize); @@ -842,7 +1013,7 @@ unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, #endif /*LODEPNG_COMPILE_DECODER*/ #ifdef LODEPNG_COMPILE_ENCODER -//Same as other lodepng::encode, but using a State for more settings and information. +/* Same as other lodepng::encode, but using a State for more settings and information. */ unsigned encode(std::vector<unsigned char>& out, const unsigned char* in, unsigned w, unsigned h, State& state); @@ -853,56 +1024,63 @@ unsigned encode(std::vector<unsigned char>& out, #ifdef LODEPNG_COMPILE_DISK /* -Load a file from disk into an std::vector. If the vector is empty, then either -the file doesn't exist or is an empty file. +Load a file from disk into an std::vector. +return value: error code (0 means ok) */ -void load_file(std::vector<unsigned char>& buffer, const std::string& filename); +unsigned load_file(std::vector<unsigned char>& buffer, const std::string& filename); /* Save the binary data in an std::vector to a file on disk. The file is overwritten without warning. */ -void save_file(const std::vector<unsigned char>& buffer, const std::string& filename); -#endif //LODEPNG_COMPILE_DISK -#endif //LODEPNG_COMPILE_PNG +unsigned save_file(const std::vector<unsigned char>& buffer, const std::string& filename); +#endif /* LODEPNG_COMPILE_DISK */ +#endif /* LODEPNG_COMPILE_PNG */ #ifdef LODEPNG_COMPILE_ZLIB #ifdef LODEPNG_COMPILE_DECODER -//Zlib-decompress an unsigned char buffer +/* Zlib-decompress an unsigned char buffer */ unsigned decompress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); -//Zlib-decompress an std::vector +/* Zlib-decompress an std::vector */ unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); -#endif //LODEPNG_COMPILE_DECODER +#endif /* LODEPNG_COMPILE_DECODER */ #ifdef LODEPNG_COMPILE_ENCODER -//Zlib-compress an unsigned char buffer +/* Zlib-compress an unsigned char buffer */ unsigned compress(std::vector<unsigned char>& out, const unsigned char* in, size_t insize, const LodePNGCompressSettings& settings = lodepng_default_compress_settings); -//Zlib-compress an std::vector +/* Zlib-compress an std::vector */ unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, const LodePNGCompressSettings& settings = lodepng_default_compress_settings); -#endif //LODEPNG_COMPILE_ENCODER -#endif //LODEPNG_COMPILE_ZLIB -} //namespace lodepng +#endif /* LODEPNG_COMPILE_ENCODER */ +#endif /* LODEPNG_COMPILE_ZLIB */ +} /* namespace lodepng */ #endif /*LODEPNG_COMPILE_CPP*/ /* TODO: [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often -[.] check compatibility with vareous compilers - done but needs to be redone for every newer version +[.] check compatibility with various compilers - done but needs to be redone for every newer version [X] converting color to 16-bit per channel types -[ ] read all public PNG chunk types (but never let the color profile and gamma ones touch RGB values) +[X] support color profile chunk types (but never let them touch RGB values by default) +[ ] support all public PNG chunk types (almost done except sBIT, sPLT and hIST) [ ] make sure encoder generates no chunks with size > (2^31)-1 [ ] partial decoding (stream processing) [X] let the "isFullyOpaque" function check color keys and transparent palettes too [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl" -[ ] don't stop decoding on errors like 69, 57, 58 (make warnings) -[ ] make option to choose if the raw image with non multiple of 8 bits per scanline should have padding bits or not +[ ] allow treating some errors like warnings, when image is recoverable (e.g. 69, 57, 58) +[ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ... +[ ] error messages with line numbers (and version) +[ ] errors in state instead of as return code? +[ ] new errors/warnings like suspiciously big decompressed ztxt or iccp chunk [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes +[ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ... +[ ] allow user to give data (void*) to custom allocator +[X] provide alternatives for C library functions not present on some platforms (memcpy, ...) */ #endif /*LODEPNG_H inclusion guard*/ @@ -932,8 +1110,9 @@ LodePNG Documentation 10. examples 10.1. decoder C++ example 10.2. decoder C example - 11. changes - 12. contact information + 11. state settings reference + 12. changes + 13. contact information 1. about @@ -996,8 +1175,10 @@ The following features are supported by the decoder: *) zlib decompression (inflate) *) zlib compression (deflate) *) CRC32 and ADLER32 checksums +*) colorimetric color profile conversions: currently experimentally available in lodepng_util.cpp only, + plus alternatively ability to pass on chroma/gamma/ICC profile information to other color management system. *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks. -*) the following chunks are supported (generated/interpreted) by both encoder and decoder: +*) the following chunks are supported by both encoder and decoder: IHDR: header information PLTE: color palette IDAT: pixel data @@ -1009,6 +1190,10 @@ The following features are supported by the decoder: bKGD: suggested background color pHYs: physical dimensions tIME: modification time + cHRM: RGB chromaticities + gAMA: RGB gamma correction + iCCP: ICC color profile + sRGB: rendering intent 1.2. features not supported --------------------------- @@ -1017,10 +1202,10 @@ The following features are _not_ supported: *) some features needed to make a conformant PNG-Editor might be still missing. *) partial loading/stream processing. All data must be available and is processed in one call. -*) The following public chunks are not supported but treated as unknown chunks by LodePNG - cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT - Some of these are not supported on purpose: LodePNG wants to provide the RGB values - stored in the pixels, not values modified by system dependent gamma or color models. +*) The following public chunks are not (yet) supported but treated as unknown chunks by LodePNG: + sBIT + hIST + sPLT 2. C and C++ version @@ -1094,7 +1279,7 @@ LodePNGColorMode info_raw When decoding, here you can specify which color type you want the resulting raw image to be. If this is different from the colortype of the PNG, then the decoder will automatically convert the result. This conversion -always works, except if you want it to convert a color PNG to greyscale or to +always works, except if you want it to convert a color PNG to grayscale or to a palette with missing colors. By default, 32-bit color is used for the result. @@ -1190,7 +1375,7 @@ can encode the colors of all pixels without information loss. An important thing to note about LodePNG, is that the color type of the PNG, and the color type of the raw image, are completely independent. By default, when you decode a PNG, you get the result as a raw image in the color type you want, -no matter whether the PNG was encoded with a palette, greyscale or RGBA color. +no matter whether the PNG was encoded with a palette, grayscale or RGBA color. And if you encode an image, by default LodePNG will automatically choose the PNG color type that gives good compression based on the values of colors and amount of colors in the image. It can be configured to let you control it instead as @@ -1198,10 +1383,10 @@ well, though. To be able to do this, LodePNG does conversions from one color mode to another. It can convert from almost any color type to any other color type, except the -following conversions: RGB to greyscale is not supported, and converting to a +following conversions: RGB to grayscale is not supported, and converting to a palette when the palette doesn't have a required color is not supported. This is not supported on purpose: this is information loss which requires a color -reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to grey +reduction algorithm that is beyond the scope of a PNG encoder (yes, RGB to gray is easy, but there are multiple ways if you want to give some channels more weight). @@ -1222,10 +1407,10 @@ decoding to have another color type, a conversion is done by LodePNG. The PNG specification gives the following color types: -0: greyscale, bit depths 1, 2, 4, 8, 16 +0: grayscale, bit depths 1, 2, 4, 8, 16 2: RGB, bit depths 8 and 16 3: palette, bit depths 1, 2, 4 and 8 -4: greyscale with alpha, bit depths 8 and 16 +4: grayscale with alpha, bit depths 8 and 16 6: RGBA, bit depths 8 and 16 Bit depth is the amount of bits per pixel per color channel. So the total amount @@ -1240,20 +1425,22 @@ behaviour. If, when decoding, you want the raw image to be something else than the default, you need to set the color type and bit depth you want in the LodePNGColorMode, -or the parameters of the simple function of LodePNG you're using. +or the parameters colortype and bitdepth of the simple decoding function. -If, when encoding, you use another color type than the default in the input +If, when encoding, you use another color type than the default in the raw input image, you need to specify its color type and bit depth in the LodePNGColorMode -of the raw image, or use the parameters of the simplefunction of LodePNG you're -using. +of the raw image, or use the parameters colortype and bitdepth of the simple +encoding function. If, when encoding, you don't want LodePNG to choose the output PNG color type but control it yourself, you need to set auto_convert in the encoder settings -to LAC_NONE, and specify the color type you want in the LodePNGInfo of the -encoder. +to false, and specify the color type you want in the LodePNGInfo of the +encoder (including palette: it can generate a palette if auto_convert is true, +otherwise not). -If you do any of the above, LodePNG may need to do a color conversion, which -follows the rules below, and may sometimes not be allowed. +If the input and output color type differ (whether user chosen or auto chosen), +LodePNG will do a color conversion, which follows the rules below, and may +sometimes result in an error. To avoid some confusion: -the decoder converts from PNG to raw image @@ -1272,31 +1459,34 @@ To avoid some confusion: the raw image correctly before encoding. -both encoder and decoder use the same color converter. +The function lodepng_convert does the color conversion. It is available in the +interface but normally isn't needed since the encoder and decoder already call +it. + Non supported color conversions: --color to greyscale: no error is thrown, but the result will look ugly because -only the red channel is taken --anything, to palette when that palette does not have that color in it: in this -case an error is thrown +-color to grayscale when non-gray pixels are present: no error is thrown, but +the result will look ugly because only the red channel is taken (it assumes all +three channels are the same in this case so ignores green and blue). The reason +no error is given is to allow converting from three-channel grayscale images to +one-channel even if there are numerical imprecisions. +-anything to palette when the palette does not have an exact match for a from-color +in it: in this case an error is thrown Supported color conversions: -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA --any grey or grey+alpha, to grey or grey+alpha +-any gray or gray+alpha, to gray or gray+alpha -anything to a palette, as long as the palette has the requested colors in it -removing alpha channel -higher to smaller bitdepth, and vice versa -If you want no color conversion to be done: +If you want no color conversion to be done (e.g. for speed or control): -In the encoder, you can make it save a PNG with any color type by giving the raw color mode and LodePNGInfo the same color mode, and setting auto_convert to -LAC_NO. +false. -In the decoder, you can make it store the pixel data in the same color type as the PNG has, by setting the color_convert setting to false. Settings in info_raw are then ignored. -The function lodepng_convert does the color conversion. It is available in the -interface but normally isn't needed since the encoder and decoder already call -it. - 6.3. padding bits ----------------- @@ -1305,7 +1495,7 @@ have a bit amount that isn't a multiple of 8, then padding bits are used so that scanline starts at a fresh byte. But that is NOT true for the LodePNG raw input and output. The raw input image you give to the encoder, and the raw output image you get from the decoder will NOT have these padding bits, e.g. in the case of a 1-bit image with a width -of 7 pixels, the first pixel of the second scanline will the the 8th bit of the first byte, +of 7 pixels, the first pixel of the second scanline will the 8th bit of the first byte, not the first bit of a new byte. 6.4. A note about 16-bits per channel and endianness @@ -1341,6 +1531,11 @@ of the error in English as a string. Check the implementation of lodepng_error_text to see the meaning of each code. +It is not recommended to use the numerical values to programmatically make +different decisions based on error types as the numbers are not guaranteed to +stay backwards compatible. They are for human consumption only. Programmatically +only 0 or non-0 matter. + 8. chunks and PNG editing ------------------------- @@ -1406,12 +1601,12 @@ Iterate to the next chunk. This works if you have a buffer with consecutive chun functions do no boundary checking of the allocated data whatsoever, so make sure there is enough data available in the buffer to be able to go to the next chunk. -unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, const unsigned char* chunk): -unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, +unsigned lodepng_chunk_append(unsigned char** out, size_t* outsize, const unsigned char* chunk): +unsigned lodepng_chunk_create(unsigned char** out, size_t* outsize, unsigned length, const char* type, const unsigned char* data): These functions are used to create new chunks that are appended to the data in *out that has -length *outlength. The append function appends an existing chunk to the new data. The create +length *outsize. The append function appends an existing chunk to the new data. The create function creates a new chunk with the given parameters and appends it. Type is the 4-letter name of the chunk. @@ -1422,7 +1617,7 @@ The LodePNGInfo struct contains fields with the unknown chunk in it. It has 3 buffers (each with size) to contain 3 types of unknown chunks: the ones that come before the PLTE chunk, the ones that come between the PLTE and the IDAT chunks, and the ones that come after the IDAT chunks. -It's necessary to make the distionction between these 3 cases because the PNG +It's necessary to make the distinction between these 3 cases because the PNG standard forces to keep the ordering of unknown chunks compared to the critical chunks, but does not force any other ordering rules. @@ -1455,6 +1650,8 @@ LodePNG. For the C++ version, only the standard C++ library is needed on top. Add the files lodepng.c(pp) and lodepng.h to your project, include lodepng.h where needed, and your program can read/write PNG files. +It is compatible with C90 and up, and C++03 and up. + If performance is important, use optimization when compiling! For both the encoder and decoder, this makes a large difference. @@ -1470,49 +1667,40 @@ LodePNG is developed in gcc so this compiler is natively supported. It gives no warnings with compiler options "-Wall -Wextra -pedantic -ansi", with gcc and g++ version 4.7.1 on Linux, 32-bit and 64-bit. -*) Mingw +*) Clang -The Mingw compiler (a port of gcc) for Windows is fully supported by LodePNG. +Fully supported and warning-free. -*) Visual Studio 2005 and up, Visual C++ Express Edition 2005 and up +*) Mingw + +The Mingw compiler (a port of gcc for Windows) should be fully supported by +LodePNG. -Visual Studio may give warnings about 'fopen' being deprecated. A multiplatform library -can't support the proposed Visual Studio alternative however, so LodePNG keeps using -fopen. If you don't want to see the deprecated warnings, put this on top of lodepng.h -before the inclusions: -#define _CRT_SECURE_NO_DEPRECATE +*) Visual Studio and Visual C++ Express Edition -Other than the above warnings, LodePNG should be warning-free with warning -level 3 (W3). Warning level 4 (W4) will give warnings about integer conversions. -I'm not planning to resolve these warnings. To get rid of them, let Visual -Studio use warning level W3 for lodepng.cpp only: right click lodepng.cpp, -Properties, C/C++, General, Warning Level: Level 3 (/W3). +LodePNG should be warning-free with warning level W4. Two warnings were disabled +with pragmas though: warning 4244 about implicit conversions, and warning 4996 +where it wants to use a non-standard function fopen_s instead of the standard C +fopen. Visual Studio may want "stdafx.h" files to be included in each source file and give an error "unexpected end of file while looking for precompiled header". -That is not standard C++ and will not be added to the stock LodePNG. You can +This is not standard C++ and will not be added to the stock LodePNG. You can disable it for lodepng.cpp only by right clicking it, Properties, C/C++, Precompiled Headers, and set it to Not Using Precompiled Headers there. -*) Visual Studio 6.0 - -LodePNG support for Visual Studio 6.0 is not guaranteed because VS6 doesn't -follow the C++ standard correctly. - -*) Comeau C/C++ - -Vesion 20070107 compiles without problems on the Comeau C/C++ Online Test Drive -at http://www.comeaucomputing.com/tryitout in both C90 and C++ mode. +NOTE: Modern versions of VS should be fully supported, but old versions, e.g. +VS6, are not guaranteed to work. *) Compilers on Macintosh -LodePNG has been reported to work both with the gcc and LLVM for Macintosh, both -for C and C++. +LodePNG has been reported to work both with gcc and LLVM for Macintosh, both for +C and C++. *) Other Compilers -If you encounter problems on other compilers, feel free to let me know and I may -try to fix it if the compiler is modern standards complient. +If you encounter problems on any compilers, feel free to let me know and I may +try to fix it if the compiler is modern and standards compliant. 10. examples @@ -1527,8 +1715,7 @@ examples can be found on the LodePNG website. #include "lodepng.h" #include <iostream> -int main(int argc, char *argv[]) -{ +int main(int argc, char *argv[]) { const char* filename = argc > 1 ? argv[1] : "test.png"; //load and decode @@ -1547,8 +1734,7 @@ int main(int argc, char *argv[]) #include "lodepng.h" -int main(int argc, char *argv[]) -{ +int main(int argc, char *argv[]) { unsigned error; unsigned char* image; size_t width, height; @@ -1564,8 +1750,51 @@ int main(int argc, char *argv[]) return 0; } - -11. changes +11. state settings reference +---------------------------- + +A quick reference of some settings to set on the LodePNGState + +For decoding: + +state.decoder.zlibsettings.ignore_adler32: ignore ADLER32 checksums +state.decoder.zlibsettings.custom_...: use custom inflate function +state.decoder.ignore_crc: ignore CRC checksums +state.decoder.ignore_critical: ignore unknown critical chunks +state.decoder.ignore_end: ignore missing IEND chunk. May fail if this corruption causes other errors +state.decoder.color_convert: convert internal PNG color to chosen one +state.decoder.read_text_chunks: whether to read in text metadata chunks +state.decoder.remember_unknown_chunks: whether to read in unknown chunks +state.info_raw.colortype: desired color type for decoded image +state.info_raw.bitdepth: desired bit depth for decoded image +state.info_raw....: more color settings, see struct LodePNGColorMode +state.info_png....: no settings for decoder but ouput, see struct LodePNGInfo + +For encoding: + +state.encoder.zlibsettings.btype: disable compression by setting it to 0 +state.encoder.zlibsettings.use_lz77: use LZ77 in compression +state.encoder.zlibsettings.windowsize: tweak LZ77 windowsize +state.encoder.zlibsettings.minmatch: tweak min LZ77 length to match +state.encoder.zlibsettings.nicematch: tweak LZ77 match where to stop searching +state.encoder.zlibsettings.lazymatching: try one more LZ77 matching +state.encoder.zlibsettings.custom_...: use custom deflate function +state.encoder.auto_convert: choose optimal PNG color type, if 0 uses info_png +state.encoder.filter_palette_zero: PNG filter strategy for palette +state.encoder.filter_strategy: PNG filter strategy to encode with +state.encoder.force_palette: add palette even if not encoding to one +state.encoder.add_id: add LodePNG identifier and version as a text chunk +state.encoder.text_compression: use compressed text chunks for metadata +state.info_raw.colortype: color type of raw input image you provide +state.info_raw.bitdepth: bit depth of raw input image you provide +state.info_raw: more color settings, see struct LodePNGColorMode +state.info_png.color.colortype: desired color type if auto_convert is false +state.info_png.color.bitdepth: desired bit depth if auto_convert is false +state.info_png.color....: more color settings, see struct LodePNGColorMode +state.info_png....: more PNG related settings, see struct LodePNGInfo + + +12. changes ----------- The version number of LodePNG is the date of the change given in the format @@ -1574,28 +1803,60 @@ yyyymmdd. Some changes aren't backwards compatible. Those are indicated with a (!) symbol. +Not all changes are listed here, the commit history in github lists more: +https://github.com/lvandeve/lodepng + +*) 17 okt 2020: prevent decoding too large text/icc chunks by default. +*) 06 mar 2020: simplified some of the dynamic memory allocations. +*) 12 jan 2020: (!) added 'end' argument to lodepng_chunk_next to allow correct + overflow checks. +*) 14 aug 2019: around 25% faster decoding thanks to huffman lookup tables. +*) 15 jun 2019: (!) auto_choose_color API changed (for bugfix: don't use palette + if gray ICC profile) and non-ICC LodePNGColorProfile renamed to + LodePNGColorStats. +*) 30 dec 2018: code style changes only: removed newlines before opening braces. +*) 10 sep 2018: added way to inspect metadata chunks without full decoding. +*) 19 aug 2018: (!) fixed color mode bKGD is encoded with and made it use + palette index in case of palette. +*) 10 aug 2018: (!) added support for gAMA, cHRM, sRGB and iCCP chunks. This + change is backwards compatible unless you relied on unknown_chunks for those. +*) 11 jun 2018: less restrictive check for pixel size integer overflow +*) 14 jan 2018: allow optionally ignoring a few more recoverable errors +*) 17 sep 2017: fix memory leak for some encoder input error cases +*) 27 nov 2016: grey+alpha auto color model detection bugfix +*) 18 apr 2016: Changed qsort to custom stable sort (for platforms w/o qsort). +*) 09 apr 2016: Fixed colorkey usage detection, and better file loading (within + the limits of pure C90). +*) 08 dec 2015: Made load_file function return error if file can't be opened. +*) 24 okt 2015: Bugfix with decoding to palette output. +*) 18 apr 2015: Boundary PM instead of just package-merge for faster encoding. +*) 24 aug 2014: Moved to github +*) 23 aug 2014: Reduced needless memory usage of decoder. +*) 28 jun 2014: Removed fix_png setting, always support palette OOB for + simplicity. Made ColorProfile public. +*) 09 jun 2014: Faster encoder by fixing hash bug and more zeros optimization. *) 22 dec 2013: Power of two windowsize required for optimization. *) 15 apr 2013: Fixed bug with LAC_ALPHA and color key. *) 25 mar 2013: Added an optional feature to ignore some PNG errors (fix_png). -*) 11 mar 2013 (!): Bugfix with custom free. Changed from "my" to "lodepng_" +*) 11 mar 2013: (!) Bugfix with custom free. Changed from "my" to "lodepng_" prefix for the custom allocators and made it possible with a new #define to use custom ones in your project without needing to change lodepng's code. *) 28 jan 2013: Bugfix with color key. *) 27 okt 2012: Tweaks in text chunk keyword length error handling. -*) 8 okt 2012 (!): Added new filter strategy (entropy) and new auto color mode. +*) 8 okt 2012: (!) Added new filter strategy (entropy) and new auto color mode. (no palette). Better deflate tree encoding. New compression tweak settings. Faster color conversions while decoding. Some internal cleanups. *) 23 sep 2012: Reduced warnings in Visual Studio a little bit. -*) 1 sep 2012 (!): Removed #define's for giving custom (de)compression functions +*) 1 sep 2012: (!) Removed #define's for giving custom (de)compression functions and made it work with function pointers instead. *) 23 jun 2012: Added more filter strategies. Made it easier to use custom alloc and free functions and toggle #defines from compiler flags. Small fixes. -*) 6 may 2012 (!): Made plugging in custom zlib/deflate functions more flexible. -*) 22 apr 2012 (!): Made interface more consistent, renaming a lot. Removed +*) 6 may 2012: (!) Made plugging in custom zlib/deflate functions more flexible. +*) 22 apr 2012: (!) Made interface more consistent, renaming a lot. Removed redundant C++ codec classes. Reduced amount of structs. Everything changed, but it is cleaner now imho and functionality remains the same. Also fixed - several bugs and shrinked the implementation code. Made new samples. -*) 6 nov 2011 (!): By default, the encoder now automatically chooses the best + several bugs and shrunk the implementation code. Made new samples. +*) 6 nov 2011: (!) By default, the encoder now automatically chooses the best PNG color model and bit depth, based on the amount and type of colors of the raw image. For this, autoLeaveOutAlphaChannel replaced by auto_choose_color. *) 9 okt 2011: simpler hash chain implementation for the encoder. @@ -1604,7 +1865,7 @@ symbol. A bug with the PNG filtertype heuristic was fixed, so that it chooses much better ones (it's quite significant). A setting to do an experimental, slow, brute force search for PNG filter types is added. -*) 17 aug 2011 (!): changed some C zlib related function names. +*) 17 aug 2011: (!) changed some C zlib related function names. *) 16 aug 2011: made the code less wide (max 120 characters per line). *) 17 apr 2011: code cleanup. Bugfixes. Convert low to 16-bit per sample colors. *) 21 feb 2011: fixed compiling for C90. Fixed compiling with sections disabled. @@ -1629,7 +1890,7 @@ symbol. *) 20 jan 2008: support for unknown chunks allowing using LodePNG for an editor. *) 18 jan 2008: support for tIME and pHYs chunks added to encoder and decoder. *) 17 jan 2008: ability to encode and decode compressed zTXt chunks added - Also vareous fixes, such as in the deflate and the padding bits code. + Also various fixes, such as in the deflate and the padding bits code. *) 13 jan 2008: Added ability to encode Adam7-interlaced images. Improved filtering code of encoder. *) 07 jan 2008: (!) changed LodePNG to use ISO C90 instead of C++. A @@ -1700,7 +1961,7 @@ symbol. *) 12 aug 2005: Initial release (C++, decoder only) -12. contact information +13. contact information ----------------------- Feel free to contact me with suggestions, problems, comments, ... concerning @@ -1712,5 +1973,5 @@ Domain: gmail dot com. Account: lode dot vandevenne. -Copyright (c) 2005-2013 Lode Vandevenne +Copyright (c) 2005-2020 Lode Vandevenne */ |