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Diffstat (limited to 'libs/libgui/png.h')
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diff --git a/libs/libgui/png.h b/libs/libgui/png.h new file mode 100644 index 0000000..dba0947 --- /dev/null +++ b/libs/libgui/png.h @@ -0,0 +1,1036 @@ +/* +LodePNG version 20201017 + +Copyright (c) 2005-2020 Lode Vandevenne +Copyright (c) 2021 Marvin Borner + +This software is provided 'as-is', without any express or implied +warranty. In no event will the authors be held liable for any damages +arising from the use of this software. + +Permission is granted to anyone to use this software for any purpose, +including commercial applications, and to alter it and redistribute it +freely, subject to the following restrictions: + + 1. The origin of this software must not be misrepresented; you must not + claim that you wrote the original software. If you use this software + in a product, an acknowledgment in the product documentation would be + appreciated but is not required. + + 2. Altered source versions must be plainly marked as such, and must not be + misrepresented as being the original software. + + 3. This notice may not be removed or altered from any source + distribution. +*/ + +#ifndef PNG_H +#define PNG_H + +/* For now! TODO: Use PNG encoding */ +#define PNG_NO_COMPILE_ENCODER + +#include <def.h> +extern const char *PNG_VERSION_STRING; + +/* +The following #defines are used to create code sections. They can be disabled +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. +-DPNG_NO_COMPILE_ZLIB for gcc. +In addition to those below, you can also define PNG_NO_COMPILE_CRC to +allow implementing a custom png_crc32. +*/ +/*deflate & zlib. If disabled, you must specify alternative zlib functions in +the custom_zlib field of the compress and decompress settings*/ +#ifndef PNG_NO_COMPILE_ZLIB +#define PNG_COMPILE_ZLIB +#endif + +/*png encoder and png decoder*/ +#ifndef PNG_NO_COMPILE_PNG +#define PNG_COMPILE_PNG +#endif + +/*deflate&zlib decoder and png decoder*/ +#ifndef PNG_NO_COMPILE_DECODER +#define PNG_COMPILE_DECODER +#endif + +/*deflate&zlib encoder and png encoder*/ +#ifndef PNG_NO_COMPILE_ENCODER +#define PNG_COMPILE_ENCODER +#endif + +/*the optional built in harddisk file loading and saving functions*/ +#ifndef PNG_NO_COMPILE_DISK +#define PNG_COMPILE_DISK +#endif + +/*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/ +#ifndef PNG_NO_COMPILE_ANCILLARY_CHUNKS +#define PNG_COMPILE_ANCILLARY_CHUNKS +#endif + +/*ability to convert error numerical codes to English text string*/ +#ifndef PNG_NO_COMPILE_ERROR_TEXT +#define PNG_COMPILE_ERROR_TEXT +#endif + +/*Compile the default allocators (C's free, malloc and realloc). If you disable this, +you can define the functions png_free, png_malloc and png_realloc in your +source files with custom allocators.*/ +#ifndef PNG_NO_COMPILE_ALLOCATORS +#define PNG_COMPILE_ALLOCATORS +#endif + +/*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/ +#ifdef __cplusplus +#ifndef PNG_NO_COMPILE_CPP +#define PNG_COMPILE_CPP +#endif +#endif + +#ifdef PNG_COMPILE_CPP +#include <string> +#include <vector> +#endif /*PNG_COMPILE_CPP*/ + +#ifdef PNG_COMPILE_PNG +/*The PNG color types (also used for raw image).*/ +typedef enum pngColorType { + 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, /*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 +} pngColorType; + +#ifdef PNG_COMPILE_DECODER +/* +Converts PNG data in memory to raw pixel data. +out: Output parameter. Pointer to buffer that will contain the raw pixel data. + After decoding, its size is w * h * (bytes per pixel) bytes larger than + initially. Bytes per pixel depends on colortype and bitdepth. + Must be freed after usage with free(*out). + Note: for 16-bit per channel colors, uses big endian format like PNG does. +w: Output parameter. Pointer to width of pixel data. +h: Output parameter. Pointer to height of pixel data. +in: Memory buffer with the PNG file. +insize: size of the in buffer. +colortype: the desired color type for the raw output image. See explanation on PNG color types. +bitdepth: the desired bit depth for the raw output image. See explanation on PNG color types. +Return value: png error code (0 means no error). +*/ +u32 png_decode_memory(u8 **out, u32 *w, u32 *h, const u8 *in, u32 insize, pngColorType colortype, + u32 bitdepth); + +/*Same as png_decode_memory, but always decodes to 32-bit RGBA raw image*/ +u32 png_decode32(u8 **out, u32 *w, u32 *h, const u8 *in, u32 insize); + +/*Same as png_decode_memory, but always decodes to 24-bit RGB raw image*/ +u32 png_decode24(u8 **out, u32 *w, u32 *h, const u8 *in, u32 insize); + +#ifdef PNG_COMPILE_DISK +/* +Load PNG from disk, from file with given name. +Same as the other decode functions, but instead takes a filename as input. +*/ +u32 png_decode_file(u8 **out, u32 *w, u32 *h, const char *filename, pngColorType colortype, + u32 bitdepth); + +/*Same as png_decode_file, but always decodes to 32-bit RGBA raw image.*/ +u32 png_decode32_file(u8 **out, u32 *w, u32 *h, const char *filename); + +/*Same as png_decode_file, but always decodes to 24-bit RGB raw image.*/ +u32 png_decode24_file(u8 **out, u32 *w, u32 *h, const char *filename); +#endif /*PNG_COMPILE_DISK*/ +#endif /*PNG_COMPILE_DECODER*/ + +#ifdef PNG_COMPILE_ENCODER +/* +Converts raw pixel data into a PNG image in memory. The colortype and bitdepth + of the output PNG image cannot be chosen, they are automatically determined + by the colortype, bitdepth and content of the input pixel data. + Note: for 16-bit per channel colors, needs big endian format like PNG does. +out: Output parameter. Pointer to buffer that will contain the PNG image data. + Must be freed after usage with free(*out). +outsize: Output parameter. Pointer to the size in bytes of the out buffer. +image: The raw pixel data to encode. The size of this buffer should be + w * h * (bytes per pixel), bytes per pixel depends on colortype and bitdepth. +w: width of the raw pixel data in pixels. +h: height of the raw pixel data in pixels. +colortype: the color type of the raw input image. See explanation on PNG color types. +bitdepth: the bit depth of the raw input image. See explanation on PNG color types. +Return value: png error code (0 means no error). +*/ +u32 png_encode_memory(u8 **out, u32 *outsize, const u8 *image, u32 w, u32 h, pngColorType colortype, + u32 bitdepth); + +/*Same as png_encode_memory, but always encodes from 32-bit RGBA raw image.*/ +u32 png_encode32(u8 **out, u32 *outsize, const u8 *image, u32 w, u32 h); + +/*Same as png_encode_memory, but always encodes from 24-bit RGB raw image.*/ +u32 png_encode24(u8 **out, u32 *outsize, const u8 *image, u32 w, u32 h); + +#ifdef PNG_COMPILE_DISK +/* +Converts raw pixel data into a PNG file on disk. +Same as the other encode functions, but instead takes a filename as output. +NOTE: This overwrites existing files without warning! +*/ +u32 png_encode_file(const char *filename, const u8 *image, u32 w, u32 h, pngColorType colortype, + u32 bitdepth); + +/*Same as png_encode_file, but always encodes from 32-bit RGBA raw image.*/ +u32 png_encode32_file(const char *filename, const u8 *image, u32 w, u32 h); + +/*Same as png_encode_file, but always encodes from 24-bit RGB raw image.*/ +u32 png_encode24_file(const char *filename, const u8 *image, u32 w, u32 h); +#endif /*PNG_COMPILE_DISK*/ +#endif /*PNG_COMPILE_ENCODER*/ + +#ifdef PNG_COMPILE_CPP +namespace png +{ +#ifdef PNG_COMPILE_DECODER +/*Same as png_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.*/ +u32 decode(std::vector<u8> &out, u32 &w, u32 &h, const u8 *in, u32 insize, + pngColorType colortype = LCT_RGBA, u32 bitdepth = 8); +u32 decode(std::vector<u8> &out, u32 &w, u32 &h, const std::vector<u8> &in, + pngColorType colortype = LCT_RGBA, u32 bitdepth = 8); +#ifdef PNG_COMPILE_DISK +/* +Converts PNG file from disk to raw pixel data in memory. +Same as the other decode functions, but instead takes a filename as input. +*/ +u32 decode(std::vector<u8> &out, u32 &w, u32 &h, const std::string &filename, + pngColorType colortype = LCT_RGBA, u32 bitdepth = 8); +#endif /* PNG_COMPILE_DISK */ +#endif /* PNG_COMPILE_DECODER */ + +#ifdef PNG_COMPILE_ENCODER +/*Same as png_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.*/ +u32 encode(std::vector<u8> &out, const u8 *in, u32 w, u32 h, pngColorType colortype = LCT_RGBA, + u32 bitdepth = 8); +u32 encode(std::vector<u8> &out, const std::vector<u8> &in, u32 w, u32 h, + pngColorType colortype = LCT_RGBA, u32 bitdepth = 8); +#ifdef PNG_COMPILE_DISK +/* +Converts 32-bit RGBA raw pixel data into a PNG file on disk. +Same as the other encode functions, but instead takes a filename as output. +NOTE: This overwrites existing files without warning! +*/ +u32 encode(const std::string &filename, const u8 *in, u32 w, u32 h, + pngColorType colortype = LCT_RGBA, u32 bitdepth = 8); +u32 encode(const std::string &filename, const std::vector<u8> &in, u32 w, u32 h, + pngColorType colortype = LCT_RGBA, u32 bitdepth = 8); +#endif /* PNG_COMPILE_DISK */ +#endif /* PNG_COMPILE_ENCODER */ +} /* namespace png */ +#endif /*PNG_COMPILE_CPP*/ +#endif /*PNG_COMPILE_PNG*/ + +#ifdef PNG_COMPILE_ERROR_TEXT +/*Returns an English description of the numerical error code.*/ +const char *png_error_text(u32 code); +#endif /*PNG_COMPILE_ERROR_TEXT*/ + +#ifdef PNG_COMPILE_DECODER +/*Settings for zlib decompression*/ +typedef struct pngDecompressSettings pngDecompressSettings; +struct pngDecompressSettings { + /* Check pngDecoderSettings for more ignorable errors such as ignore_crc */ + u32 ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ + u32 ignore_nlen; /*ignore complement of len checksum in uncompressed blocks*/ + + /*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).*/ + u32 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).*/ + u32 (*custom_zlib)(u8 **, u32 *, const u8 *, u32, const pngDecompressSettings *); + /*use custom deflate decoder instead of built in one (default: null) + 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).*/ + u32 (*custom_inflate)(u8 **, u32 *, const u8 *, u32, const pngDecompressSettings *); + + const void *custom_context; /*optional custom settings for custom functions*/ +}; + +extern const pngDecompressSettings png_default_decompress_settings; +void png_decompress_settings_init(pngDecompressSettings *settings); +#endif /*PNG_COMPILE_DECODER*/ + +#ifdef PNG_COMPILE_ENCODER +/* +Settings for zlib compression. Tweaking these settings tweaks the balance +between speed and compression ratio. +*/ +typedef struct pngCompressSettings pngCompressSettings; +struct pngCompressSettings /*deflate = compress*/ { + /*LZ77 related settings*/ + u32 btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/ + u32 use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/ + u32 windowsize; /*must be a power of two <= 32768. higher compresses more but is slower. Default value: 2048.*/ + u32 minmatch; /*minimum lz77 length. 3 is normally best, 6 can be better for some PNGs. Default: 0*/ + u32 nicematch; /*stop searching if >= this length found. Set to 258 for best compression. Default: 128*/ + u32 lazymatching; /*use lazy matching: better compression but a bit slower. Default: true*/ + + /*use custom zlib encoder instead of built in one (default: null)*/ + u32 (*custom_zlib)(u8 **, u32 *, const u8 *, u32, const pngCompressSettings *); + /*use custom deflate encoder 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*/ + u32 (*custom_deflate)(u8 **, u32 *, const u8 *, u32, const pngCompressSettings *); + + const void *custom_context; /*optional custom settings for custom functions*/ +}; + +extern const pngCompressSettings png_default_compress_settings; +void png_compress_settings_init(pngCompressSettings *settings); +#endif /*PNG_COMPILE_ENCODER*/ + +#ifdef PNG_COMPILE_PNG +/* +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 png. +*/ +typedef struct pngColorMode { + /*header (IHDR)*/ + pngColorType + colortype; /*color type, see PNG standard or documentation further in this header file*/ + u32 bitdepth; /*bits per sample, see PNG standard or documentation further in this header file*/ + + /* + palette (PLTE and tRNS) + + Dynamically allocated with the colors of the palette, including alpha. + This field may not be allocated directly, use png_color_mode_init first, + then png_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 png already + fills the palette colors in the pixels of the raw RGBA output. + + The palette is only supported for color type 3. + */ + u8 *palette; /*palette in RGBARGBA... order. Must be either 0, or when allocated must have 1024 bytes*/ + u32 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 grayscale PNGs, r, g and b will all 3 be set to the same. + + When decoding, by default you can ignore this information, since png sets + pixels with this key to transparent already in the raw RGBA output. + + The color key is only supported for color types 0 and 2. + */ + u32 key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ + u32 key_r; /*red/grayscale component of color key*/ + u32 key_g; /*green component of color key*/ + u32 key_b; /*blue component of color key*/ +} pngColorMode; + +/*init, cleanup and copy functions to use with this struct*/ +void png_color_mode_init(pngColorMode *info); +void png_color_mode_cleanup(pngColorMode *info); +/*return value is error code (0 means no error)*/ +u32 png_color_mode_copy(pngColorMode *dest, const pngColorMode *source); +/* Makes a temporary pngColorMode that does not need cleanup (no palette) */ +pngColorMode png_color_mode_make(pngColorType colortype, u32 bitdepth); + +void png_palette_clear(pngColorMode *info); +/*add 1 color to the palette*/ +u32 png_palette_add(pngColorMode *info, u8 r, u8 g, u8 b, u8 a); + +/*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ +u32 png_get_bpp(const pngColorMode *info); +/*get the amount of color channels used, based on colortype in the struct. +If a palette is used, it counts as 1 channel.*/ +u32 png_get_channels(const pngColorMode *info); +/*is it a grayscale type? (only colortype 0 or 4)*/ +u32 png_is_greyscale_type(const pngColorMode *info); +/*has it got an alpha channel? (only colortype 2 or 6)*/ +u32 png_is_alpha_type(const pngColorMode *info); +/*has it got a palette? (only colortype 3)*/ +u32 png_is_palette_type(const pngColorMode *info); +/*only returns true if there is a palette and there is a value in the palette with alpha < 255. +Loops through the palette to check this.*/ +u32 png_has_palette_alpha(const pngColorMode *info); +/* +Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image. +Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels). +Returns false if the image can only have opaque pixels. +In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values, +or if "key_defined" is true. +*/ +u32 png_can_have_alpha(const pngColorMode *info); +/*Returns the byte size of a raw image buffer with given width, height and color mode*/ +u32 png_get_raw_size(u32 w, u32 h, const pngColorMode *color); + +#ifdef PNG_COMPILE_ANCILLARY_CHUNKS +/*The information of a Time chunk in PNG.*/ +typedef struct pngTime { + u32 year; /*2 bytes used (0-65535)*/ + u32 month; /*1-12*/ + u32 day; /*1-31*/ + u32 hour; /*0-23*/ + u32 minute; /*0-59*/ + u32 second; /*0-60 (to allow for leap seconds)*/ +} pngTime; +#endif /*PNG_COMPILE_ANCILLARY_CHUNKS*/ + +/*Information about the PNG image, except pixels, width and height.*/ +typedef struct pngInfo { + /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/ + u32 compression_method; /*compression method of the original file. Always 0.*/ + u32 filter_method; /*filter method of the original file*/ + u32 interlace_method; /*interlace method of the original file: 0=none, 1=Adam7*/ + pngColorMode color; /*color type and bits, palette and transparency of the PNG file*/ + +#ifdef PNG_COMPILE_ANCILLARY_CHUNKS + /* + 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 u32 integer. + + For grayscale and palette PNGs, the value is stored in background_r. The values + in background_g and background_b are then unused. + + So when decoding, you may get these in a different color mode than the one you requested + for the raw 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. + */ + u32 background_defined; /*is a suggested background color given?*/ + u32 background_r; /*red/gray/palette component of suggested background color*/ + u32 background_g; /*green component of suggested background color*/ + u32 background_b; /*blue component of suggested background color*/ + + /* + 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. + + 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 png_add_text and png_clear_text. + + Standard text chunk keywords and strings are encoded using Latin-1. + */ + u32 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) + Similar to the non-international text chunks, but with additional strings + "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. + */ + u32 itext_num; /*the amount of international texts in this PNG*/ + char **itext_keys; /*the English keyword of the text chunk (e.g. "Comment")*/ + char **itext_langtags; /*language tag for this text's language, ISO/IEC 646 string, e.g. ISO 639 language tag*/ + char **itext_transkeys; /*keyword translated to the international language - UTF-8 string*/ + char **itext_strings; /*the actual international text - UTF-8 string*/ + + /*time chunk (tIME)*/ + u32 time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ + pngTime time; + + /*phys chunk (pHYs)*/ + u32 phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/ + u32 phys_x; /*pixels per unit in x direction*/ + u32 phys_y; /*pixels per unit in y direction*/ + u32 phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/ + + /* + Color profile related chunks: gAMA, cHRM, sRGB, iCPP + + png 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. */ + u32 gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */ + u32 gama_gamma; /* Gamma exponent times 100000 */ + + /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */ + u32 chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */ + u32 chrm_white_x; /* White Point x times 100000 */ + u32 chrm_white_y; /* White Point y times 100000 */ + u32 chrm_red_x; /* Red x times 100000 */ + u32 chrm_red_y; /* Red y times 100000 */ + u32 chrm_green_x; /* Green x times 100000 */ + u32 chrm_green_y; /* Green y times 100000 */ + u32 chrm_blue_x; /* Blue x times 100000 */ + u32 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. + */ + u32 srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */ + u32 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. + + png 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 png) 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 png 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. + */ + u32 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 png_set_icc and png_clear_icc. + */ + u8 *iccp_profile; + u32 iccp_profile_size; /* The size of iccp_profile in bytes */ + + /* End of color profile related chunks */ + + /* + unknown chunks: chunks not known by png, 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 png (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 png_chunk_next and png_chunk_append, to read/write this struct. + */ + u8 *unknown_chunks_data[3]; + u32 unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ +#endif /*PNG_COMPILE_ANCILLARY_CHUNKS*/ +} pngInfo; + +/*init, cleanup and copy functions to use with this struct*/ +void png_info_init(pngInfo *info); +void png_info_cleanup(pngInfo *info); +/*return value is error code (0 means no error)*/ +u32 png_info_copy(pngInfo *dest, const pngInfo *source); + +#ifdef PNG_COMPILE_ANCILLARY_CHUNKS +u32 png_add_text(pngInfo *info, const char *key, const char *str); /*push back both texts at once*/ +void png_clear_text(pngInfo *info); /*use this to clear the texts again after you filled them in*/ + +u32 png_add_itext(pngInfo *info, const char *key, const char *langtag, const char *transkey, + const char *str); /*push back the 4 texts of 1 chunk at once*/ +void png_clear_itext(pngInfo *info); /*use this to clear the itexts again after you filled them in*/ + +/*replaces if exists*/ +u32 png_set_icc(pngInfo *info, const char *name, const u8 *profile, u32 profile_size); +void png_clear_icc(pngInfo *info); /*use this to clear the texts again after you filled them in*/ +#endif /*PNG_COMPILE_ANCILLARY_CHUNKS*/ + +/* +Converts raw buffer from one color type to another color type, based on +pngColorMode 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 = png 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 (png_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 png error code +*/ +u32 png_convert(u8 *out, const u8 *in, const pngColorMode *mode_out, const pngColorMode *mode_in, + u32 w, u32 h); + +#ifdef PNG_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 pngDecoderSettings { + pngDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ + + /* Check pngDecompressSettings for more ignorable errors such as ignore_adler32 */ + u32 ignore_crc; /*ignore CRC checksums*/ + u32 ignore_critical; /*ignore unknown critical chunks*/ + u32 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... */ + + u32 color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/ + +#ifdef PNG_COMPILE_ANCILLARY_CHUNKS + u32 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 pngInfo (off by default, useful for a png editor)*/ + u32 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. */ + u32 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. */ + u32 max_icc_size; +#endif /*PNG_COMPILE_ANCILLARY_CHUNKS*/ +} pngDecoderSettings; + +void png_decoder_settings_init(pngDecoderSettings *settings); +#endif /*PNG_COMPILE_DECODER*/ + +#ifdef PNG_COMPILE_ENCODER +/*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ +typedef enum pngFilterStrategy { + /*every filter at zero*/ + 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.*/ + LFS_ENTROPY, + /* + Brute-force-search PNG filters by compressing each filter for each scanline. + Experimental, very slow, and only rarely gives better compression than MINSUM. + */ + LFS_BRUTE_FORCE, + /*use predefined_filters buffer: you specify the filter type for each scanline*/ + LFS_PREDEFINED +} pngFilterStrategy; + +/*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 pngColorStats { + u32 colored; /*not grayscale*/ + u32 key; /*image is not opaque and color key is possible instead of full alpha*/ + u16 key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/ + u16 key_g; + u16 key_b; + u32 alpha; /*image is not opaque and alpha channel or alpha palette required*/ + u32 numcolors; /*amount of colors, up to 257. Not valid if bits == 16 or allow_palette is disabled.*/ + u8 palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order, only valid when numcolors is valid*/ + u32 bits; /*bits per channel (not for palette). 1,2 or 4 for grayscale only. 16 if 16-bit per channel required.*/ + u32 numpixels; + + /*user settings for computing/using the stats*/ + u32 allow_palette; /*default 1. if 0, disallow choosing palette colortype in auto_choose_color, and don't count numcolors*/ + u32 allow_greyscale; /*default 1. if 0, choose RGB or RGBA even if the image only has gray colors*/ +} pngColorStats; + +void png_color_stats_init(pngColorStats *stats); + +/*Get a pngColorStats of the image. The stats must already have been inited. +Returns error code (e.g. alloc fail) or 0 if ok.*/ +u32 png_compute_color_stats(pngColorStats *stats, const u8 *image, u32 w, u32 h, + const pngColorMode *mode_in); + +/*Settings for the encoder.*/ +typedef struct pngEncoderSettings { + pngCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ + + u32 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 + completely follow the official PNG heuristic, filter_palette_zero must be true and + filter_strategy must be LFS_MINSUM*/ + u32 filter_palette_zero; + /*Which filter strategy to use when not using zeroes due to filter_palette_zero. + Set filter_palette_zero to 0 to ensure always using your chosen strategy. Default: LFS_MINSUM*/ + pngFilterStrategy filter_strategy; + /*used if filter_strategy is LFS_PREDEFINED. In that case, this must point to a buffer with + the same length as the amount of scanlines in the image, and each value must <= 5. You + have to cleanup this buffer, png will never free it. Don't forget that filter_palette_zero + must be set to 0 to ensure this is also used on palette or low bitdepth images.*/ + const u8 *predefined_filters; + + /*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). + If colortype is 3, PLTE is _always_ created.*/ + u32 force_palette; +#ifdef PNG_COMPILE_ANCILLARY_CHUNKS + /*add png identifier and version as a text chunk, for debugging*/ + u32 add_id; + /*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ + u32 text_compression; +#endif /*PNG_COMPILE_ANCILLARY_CHUNKS*/ +} pngEncoderSettings; + +void png_encoder_settings_init(pngEncoderSettings *settings); +#endif /*PNG_COMPILE_ENCODER*/ + +#if defined(PNG_COMPILE_DECODER) || defined(PNG_COMPILE_ENCODER) +/*The settings, state and information for extended encoding and decoding.*/ +typedef struct pngState { +#ifdef PNG_COMPILE_DECODER + pngDecoderSettings decoder; /*the decoding settings*/ +#endif /*PNG_COMPILE_DECODER*/ +#ifdef PNG_COMPILE_ENCODER + pngEncoderSettings encoder; /*the encoding settings*/ +#endif /*PNG_COMPILE_ENCODER*/ + pngColorMode + info_raw; /*specifies the format in which you would like to get the raw pixel buffer*/ + pngInfo info_png; /*info of the PNG image obtained after decoding*/ + u32 error; +} pngState; + +/*init, cleanup and copy functions to use with this struct*/ +void png_state_init(pngState *state); +void png_state_cleanup(pngState *state); +void png_state_copy(pngState *dest, const pngState *source); +#endif /* defined(PNG_COMPILE_DECODER) || defined(PNG_COMPILE_ENCODER) */ + +#ifdef PNG_COMPILE_DECODER +/* +Same as png_decode_memory, but uses a pngState to allow custom settings and +getting much more information about the PNG image and color mode. +*/ +u32 png_decode(u8 **out, u32 *w, u32 *h, pngState *state, const u8 *in, u32 insize); + +/* +Read the PNG header, but not the actual data. This returns only the information +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 pngState. +*/ +u32 png_inspect(u32 *w, u32 *h, pngState *state, const u8 *in, u32 insize); +#endif /*PNG_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 png_inspect first with a new state, then e.g. png_chunk_find_const +to find the desired chunk type, and if non null use png_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 +png_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. +*/ +u32 png_inspect_chunk(pngState *state, u32 pos, const u8 *in, u32 insize); + +#ifdef PNG_COMPILE_ENCODER +/*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ +u32 png_encode(u8 **out, u32 *outsize, const u8 *image, u32 w, u32 h, pngState *state); +#endif /*PNG_COMPILE_ENCODER*/ + +/* +The png_chunk functions are normally not needed, except to traverse the +unknown chunks stored in the pngInfo struct, or add new ones to it. +It also allows traversing the chunks of an encoded PNG file yourself. + +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 +*/ + +/* +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. +*/ +u32 png_chunk_length(const u8 *chunk); + +/*puts the 4-byte type in null terminated string*/ +void png_chunk_type(char type[5], const u8 *chunk); + +/*check if the type is the given type*/ +u8 png_chunk_type_equals(const u8 *chunk, const char *type); + +/*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ +u8 png_chunk_ancillary(const u8 *chunk); + +/*0: public, 1: private (see PNG standard)*/ +u8 png_chunk_private(const u8 *chunk); + +/*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ +u8 png_chunk_safetocopy(const u8 *chunk); + +/*get pointer to the data of the chunk, where the input points to the header of the chunk*/ +u8 *png_chunk_data(u8 *chunk); +const u8 *png_chunk_data_const(const u8 *chunk); + +/*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ +u32 png_chunk_check_crc(const u8 *chunk); + +/*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/ +void png_chunk_generate_crc(u8 *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 png_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". +*/ +u8 *png_chunk_next(u8 *chunk, u8 *end); +const u8 *png_chunk_next_const(const u8 *chunk, const u8 *end); + +/*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/ +u8 *png_chunk_find(u8 *chunk, u8 *end, const char type[5]); +const u8 *png_chunk_find_const(const u8 *chunk, const u8 *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 outsize are updated to reflect the new reallocated buffer. +Returns error code (0 if it went ok) +*/ +u32 png_chunk_append(u8 **out, u32 *outsize, const u8 *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 outsize are updated to reflect the new reallocated buffer. +Returne error code (0 if it went ok) +*/ +u32 png_chunk_create(u8 **out, u32 *outsize, u32 length, const char *type, const u8 *data); + +/*Calculate CRC32 of buffer*/ +u32 png_crc32(const u8 *buf, u32 len); +#endif /*PNG_COMPILE_PNG*/ + +#ifdef PNG_COMPILE_ZLIB +/* +This zlib part can be used independently to zlib compress and decompress a +buffer. It cannot be used to create gzip files however, and it only supports the +part of zlib that is required for PNG, it does not support dictionaries. +*/ + +#ifdef PNG_COMPILE_DECODER +/*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/ +u32 png_inflate(u8 **out, u32 *outsize, const u8 *in, u32 insize, + const pngDecompressSettings *settings); + +/* +Decompresses Zlib data. Reallocates the out buffer and appends the data. The +data must be according to the zlib specification. +Either, *out must be NULL and *outsize must be 0, or, *out must be a valid +buffer and *outsize its size in bytes. out must be freed by user after usage. +*/ +u32 png_zlib_decompress(u8 **out, u32 *outsize, const u8 *in, u32 insize, + const pngDecompressSettings *settings); +#endif /*PNG_COMPILE_DECODER*/ + +#ifdef PNG_COMPILE_ENCODER +/* +Compresses data with Zlib. Reallocates the out buffer and appends the data. +Zlib adds a small header and trailer around the deflate data. +The data is output in the format of the zlib specification. +Either, *out must be NULL and *outsize must be 0, or, *out must be a valid +buffer and *outsize its size in bytes. out must be freed by user after usage. +*/ +u32 png_zlib_compress(u8 **out, u32 *outsize, const u8 *in, u32 insize, + const pngCompressSettings *settings); + +/* +Find length-limited Huffman code for given frequencies. This function is in the +public interface only for tests, it's used internally by png_deflate. +*/ +u32 png_huffman_code_lengths(u32 *lengths, const u32 *frequencies, u32 numcodes, u32 maxbitlen); + +/*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ +u32 png_deflate(u8 **out, u32 *outsize, const u8 *in, u32 insize, + const pngCompressSettings *settings); + +#endif /*PNG_COMPILE_ENCODER*/ +#endif /*PNG_COMPILE_ZLIB*/ + +#ifdef PNG_COMPILE_DISK +/* +Load a file from disk into buffer. The function allocates the out buffer, and +after usage you should free it. +out: output parameter, contains pointer to loaded buffer. +outsize: output parameter, size of the allocated out buffer +filename: the path to the file to load +return value: error code (0 means ok) +*/ +u32 png_load_file(u8 **out, u32 *outsize, const char *filename); + +/* +Save a file from buffer to disk. Warning, if it exists, this function overwrites +the file without warning! +buffer: the buffer to write +buffersize: size of the buffer to write +filename: the path to the file to save to +return value: error code (0 means ok) +*/ +u32 png_save_file(const u8 *buffer, u32 buffersize, const char *filename); +#endif /*PNG_COMPILE_DISK*/ + +#ifdef PNG_COMPILE_CPP +/* The png C++ wrapper uses std::vectors instead of manually allocated memory buffers. */ +namespace png +{ +#ifdef PNG_COMPILE_PNG +class State : public pngState { + public: + State(); + State(const State &other); + ~State(); + State &operator=(const State &other); +}; + +#ifdef PNG_COMPILE_DECODER +/* Same as other png::decode, but using a State for more settings and information. */ +u32 decode(std::vector<u8> &out, u32 &w, u32 &h, State &state, const u8 *in, u32 insize); +u32 decode(std::vector<u8> &out, u32 &w, u32 &h, State &state, const std::vector<u8> &in); +#endif /*PNG_COMPILE_DECODER*/ + +#ifdef PNG_COMPILE_ENCODER +/* Same as other png::encode, but using a State for more settings and information. */ +u32 encode(std::vector<u8> &out, const u8 *in, u32 w, u32 h, State &state); +u32 encode(std::vector<u8> &out, const std::vector<u8> &in, u32 w, u32 h, State &state); +#endif /*PNG_COMPILE_ENCODER*/ + +#ifdef PNG_COMPILE_DISK +/* +Load a file from disk into an std::vector. +return value: error code (0 means ok) +*/ +u32 load_file(std::vector<u8> &buffer, const std::string &filename); + +/* +Save the binary data in an std::vector to a file on disk. The file is overwritten +without warning. +*/ +u32 save_file(const std::vector<u8> &buffer, const std::string &filename); +#endif /* PNG_COMPILE_DISK */ +#endif /* PNG_COMPILE_PNG */ + +#ifdef PNG_COMPILE_ZLIB +#ifdef PNG_COMPILE_DECODER +/* Zlib-decompress an u8 buffer */ +u32 decompress(std::vector<u8> &out, const u8 *in, u32 insize, + const pngDecompressSettings &settings = png_default_decompress_settings); + +/* Zlib-decompress an std::vector */ +u32 decompress(std::vector<u8> &out, const std::vector<u8> &in, + const pngDecompressSettings &settings = png_default_decompress_settings); +#endif /* PNG_COMPILE_DECODER */ + +#ifdef PNG_COMPILE_ENCODER +/* Zlib-compress an u8 buffer */ +u32 compress(std::vector<u8> &out, const u8 *in, u32 insize, + const pngCompressSettings &settings = png_default_compress_settings); + +/* Zlib-compress an std::vector */ +u32 compress(std::vector<u8> &out, const std::vector<u8> &in, + const pngCompressSettings &settings = png_default_compress_settings); +#endif /* PNG_COMPILE_ENCODER */ +#endif /* PNG_COMPILE_ZLIB */ +} /* namespace png */ +#endif /*PNG_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 various compilers - done but needs to be redone for every newer version +[X] converting color to 16-bit per channel types +[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" +[ ] 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 png 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 /*PNG_H inclusion guard*/ |