/* | |
LodePNG version 20161127 | |
Copyright (c) 2005-2016 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 | |
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 LODEPNG_H | |
#define LODEPNG_H | |
#include <string.h> /*for size_t*/ | |
extern const char* LODEPNG_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. | |
-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 | |
#define LODEPNG_COMPILE_CPP | |
#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*/ | |
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*/ | |
} LodePNGColorType; | |
#ifdef LODEPNG_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: LodePNG error code (0 means no error). | |
*/ | |
unsigned lodepng_decode_memory(unsigned char** out, unsigned* w, unsigned* h, | |
const unsigned char* in, size_t insize, | |
LodePNGColorType colortype, unsigned bitdepth); | |
/*Same as lodepng_decode_memory, but always decodes to 32-bit RGBA raw image*/ | |
unsigned lodepng_decode32(unsigned char** out, unsigned* w, unsigned* h, | |
const unsigned char* in, size_t insize); | |
/*Same as lodepng_decode_memory, but always decodes to 24-bit RGB raw image*/ | |
unsigned lodepng_decode24(unsigned char** out, unsigned* w, unsigned* h, | |
const unsigned char* in, size_t insize); | |
#ifdef LODEPNG_COMPILE_DISK | |
/* | |
Load PNG from disk, from file with given name. | |
Same as the other decode functions, but instead takes a filename as input. | |
*/ | |
unsigned lodepng_decode_file(unsigned char** out, unsigned* w, unsigned* h, | |
const char* filename, | |
LodePNGColorType colortype, unsigned bitdepth); | |
/*Same as lodepng_decode_file, but always decodes to 32-bit RGBA raw image.*/ | |
unsigned lodepng_decode32_file(unsigned char** out, unsigned* w, unsigned* h, | |
const char* filename); | |
/*Same as lodepng_decode_file, but always decodes to 24-bit RGB raw image.*/ | |
unsigned lodepng_decode24_file(unsigned char** out, unsigned* w, unsigned* h, | |
const char* filename); | |
#endif /*LODEPNG_COMPILE_DISK*/ | |
#endif /*LODEPNG_COMPILE_DECODER*/ | |
#ifdef LODEPNG_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: LodePNG error code (0 means no error). | |
*/ | |
unsigned lodepng_encode_memory(unsigned char** out, size_t* outsize, | |
const unsigned char* image, unsigned w, unsigned h, | |
LodePNGColorType colortype, unsigned bitdepth); | |
/*Same as lodepng_encode_memory, but always encodes from 32-bit RGBA raw image.*/ | |
unsigned lodepng_encode32(unsigned char** out, size_t* outsize, | |
const unsigned char* image, unsigned w, unsigned h); | |
/*Same as lodepng_encode_memory, but always encodes from 24-bit RGB raw image.*/ | |
unsigned lodepng_encode24(unsigned char** out, size_t* outsize, | |
const unsigned char* image, unsigned w, unsigned h); | |
#ifdef LODEPNG_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! | |
*/ | |
unsigned lodepng_encode_file(const char* filename, | |
const unsigned char* image, unsigned w, unsigned h, | |
LodePNGColorType colortype, unsigned bitdepth); | |
/*Same as lodepng_encode_file, but always encodes from 32-bit RGBA raw image.*/ | |
unsigned lodepng_encode32_file(const char* filename, | |
const unsigned char* image, unsigned w, unsigned h); | |
/*Same as lodepng_encode_file, but always encodes from 24-bit RGB raw image.*/ | |
unsigned lodepng_encode24_file(const char* filename, | |
const unsigned char* image, unsigned w, unsigned h); | |
#endif /*LODEPNG_COMPILE_DISK*/ | |
#endif /*LODEPNG_COMPILE_ENCODER*/ | |
#ifdef LODEPNG_COMPILE_CPP | |
namespace lodepng | |
{ | |
#ifdef LODEPNG_COMPILE_DECODER | |
/*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); | |
unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, | |
const std::vector<unsigned char>& in, | |
LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
#ifdef LODEPNG_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. | |
*/ | |
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 */ | |
#ifdef LODEPNG_COMPILE_ENCODER | |
/*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); | |
unsigned encode(std::vector<unsigned char>& out, | |
const std::vector<unsigned char>& in, unsigned w, unsigned h, | |
LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
#ifdef LODEPNG_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! | |
*/ | |
unsigned encode(const std::string& filename, | |
const unsigned char* in, unsigned w, unsigned h, | |
LodePNGColorType colortype = LCT_RGBA, unsigned bitdepth = 8); | |
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_CPP*/ | |
#endif /*LODEPNG_COMPILE_PNG*/ | |
#ifdef LODEPNG_COMPILE_ERROR_TEXT | |
/*Returns an English description of the numerical error code.*/ | |
const char* lodepng_error_text(unsigned code); | |
#endif /*LODEPNG_COMPILE_ERROR_TEXT*/ | |
#ifdef LODEPNG_COMPILE_DECODER | |
/*Settings for zlib decompression*/ | |
typedef struct LodePNGDecompressSettings LodePNGDecompressSettings; | |
struct LodePNGDecompressSettings | |
{ | |
unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/ | |
/*use custom zlib decoder instead of built in one (default: null)*/ | |
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*/ | |
unsigned (*custom_inflate)(unsigned char**, size_t*, | |
const unsigned char*, size_t, | |
const LodePNGDecompressSettings*); | |
const void* custom_context; /*optional custom settings for custom functions*/ | |
}; | |
extern const LodePNGDecompressSettings lodepng_default_decompress_settings; | |
void lodepng_decompress_settings_init(LodePNGDecompressSettings* settings); | |
#endif /*LODEPNG_COMPILE_DECODER*/ | |
#ifdef LODEPNG_COMPILE_ENCODER | |
/* | |
Settings for zlib compression. Tweaking these settings tweaks the balance | |
between speed and compression ratio. | |
*/ | |
typedef struct LodePNGCompressSettings LodePNGCompressSettings; | |
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. Default value: 2048.*/ | |
unsigned minmatch; /*mininum 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*/ | |
/*use custom zlib encoder instead of built in one (default: null)*/ | |
unsigned (*custom_zlib)(unsigned char**, size_t*, | |
const unsigned char*, size_t, | |
const LodePNGCompressSettings*); | |
/*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*/ | |
unsigned (*custom_deflate)(unsigned char**, size_t*, | |
const unsigned char*, size_t, | |
const LodePNGCompressSettings*); | |
const void* custom_context; /*optional custom settings for custom functions*/ | |
}; | |
extern const LodePNGCompressSettings lodepng_default_compress_settings; | |
void lodepng_compress_settings_init(LodePNGCompressSettings* settings); | |
#endif /*LODEPNG_COMPILE_ENCODER*/ | |
#ifdef LODEPNG_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 LodePNG. | |
*/ | |
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*/ | |
/* | |
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. | |
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)*/ | |
/* | |
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. | |
When decoding, by default you can ignore this information, since LodePNG 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. | |
*/ | |
unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/ | |
unsigned key_r; /*red/greyscale component of color key*/ | |
unsigned key_g; /*green component of color key*/ | |
unsigned key_b; /*blue component of color key*/ | |
} LodePNGColorMode; | |
/*init, cleanup and copy functions to use with this struct*/ | |
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); | |
void lodepng_palette_clear(LodePNGColorMode* info); | |
/*add 1 color to the palette*/ | |
unsigned lodepng_palette_add(LodePNGColorMode* info, | |
unsigned char r, unsigned char g, unsigned char b, unsigned char a); | |
/*get the total amount of bits per pixel, based on colortype and bitdepth in the struct*/ | |
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)*/ | |
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); | |
/*has it got a palette? (only colortype 3)*/ | |
unsigned lodepng_is_palette_type(const LodePNGColorMode* 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.*/ | |
unsigned lodepng_has_palette_alpha(const LodePNGColorMode* 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. | |
*/ | |
unsigned lodepng_can_have_alpha(const LodePNGColorMode* info); | |
/*Returns the byte size of a raw image buffer with given width, height and color mode*/ | |
size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* color); | |
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
/*The information of a Time chunk in PNG.*/ | |
typedef struct LodePNGTime | |
{ | |
unsigned year; /*2 bytes used (0-65535)*/ | |
unsigned month; /*1-12*/ | |
unsigned day; /*1-31*/ | |
unsigned hour; /*0-23*/ | |
unsigned minute; /*0-59*/ | |
unsigned second; /*0-60 (to allow for leap seconds)*/ | |
} LodePNGTime; | |
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
/*Information about the PNG image, except pixels, width and height.*/ | |
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*/ | |
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. | |
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. | |
The decoder does not use this background color to edit the color of pixels. | |
*/ | |
unsigned background_defined; /*is a suggested background color given?*/ | |
unsigned background_r; /*red 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) | |
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. | |
Don't allocate these text buffers yourself. Use the init/cleanup functions | |
correctly and use lodepng_add_text and lodepng_clear_text. | |
*/ | |
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) | |
Similar to the non-international text chunks, but with additional strings | |
"langtags" and "transkeys". | |
*/ | |
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")*/ | |
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)*/ | |
unsigned time_defined; /*set to 1 to make the encoder generate a tIME chunk*/ | |
LodePNGTime time; | |
/*phys chunk (pHYs)*/ | |
unsigned phys_defined; /*if 0, there is no pHYs chunk and the values below are undefined, if 1 else there is one*/ | |
unsigned phys_x; /*pixels per unit in x direction*/ | |
unsigned phys_y; /*pixels per unit in y direction*/ | |
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 | |
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. | |
*/ | |
unsigned char* unknown_chunks_data[3]; | |
size_t unknown_chunks_size[3]; /*size in bytes of the unknown chunks, given for protection*/ | |
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
} LodePNGInfo; | |
/*init, cleanup and copy functions to use with this struct*/ | |
void lodepng_info_init(LodePNGInfo* info); | |
void lodepng_info_cleanup(LodePNGInfo* info); | |
/*return value is error code (0 means no error)*/ | |
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_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*/ | |
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
/* | |
Converts raw buffer from one color type to another color type, based on | |
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). | |
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, | |
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 | |
{ | |
LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/ | |
unsigned ignore_crc; /*ignore CRC checksums*/ | |
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; | |
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
} LodePNGDecoderSettings; | |
void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings); | |
#endif /*LODEPNG_COMPILE_DECODER*/ | |
#ifdef LODEPNG_COMPILE_ENCODER | |
/*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/ | |
typedef enum LodePNGFilterStrategy | |
{ | |
/*every filter at zero*/ | |
LFS_ZERO, | |
/*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 | |
} LodePNGFilterStrategy; | |
/*Gives characteristics about the colors of the image, 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 LodePNGColorProfile | |
{ | |
unsigned colored; /*not greyscale*/ | |
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.*/ | |
unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order*/ | |
unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for greyscale only. 16 if 16-bit per channel required.*/ | |
} LodePNGColorProfile; | |
void lodepng_color_profile_init(LodePNGColorProfile* profile); | |
/*Get a LodePNGColorProfile of the image.*/ | |
unsigned lodepng_get_color_profile(LodePNGColorProfile* profile, | |
const unsigned char* image, unsigned w, unsigned h, | |
const LodePNGColorMode* mode_in); | |
/*The function LodePNG uses internally to decide the PNG color with auto_convert. | |
Chooses an optimal color model, e.g. grey if only grey pixels, palette if < 256 colors, ...*/ | |
unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out, | |
const unsigned char* image, unsigned w, unsigned h, | |
const LodePNGColorMode* mode_in); | |
/*Settings for the encoder.*/ | |
typedef struct LodePNGEncoderSettings | |
{ | |
LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/ | |
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 | |
completely follow the official PNG heuristic, filter_palette_zero must be true and | |
filter_strategy must be LFS_MINSUM*/ | |
unsigned 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*/ | |
LodePNGFilterStrategy 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, LodePNG 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 unsigned char* predefined_filters; | |
/*force creating a PLTE chunk if colortype is 2 or 6 (= a suggested palette). | |
If colortype is 3, PLTE is _always_ created.*/ | |
unsigned force_palette; | |
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS | |
/*add LodePNG identifier and version as a text chunk, for debugging*/ | |
unsigned add_id; | |
/*encode text chunks as zTXt chunks instead of tEXt chunks, and use compression in iTXt chunks*/ | |
unsigned text_compression; | |
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/ | |
} LodePNGEncoderSettings; | |
void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings); | |
#endif /*LODEPNG_COMPILE_ENCODER*/ | |
#if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) | |
/*The settings, state and information for extended encoding and decoding.*/ | |
typedef struct LodePNGState | |
{ | |
#ifdef LODEPNG_COMPILE_DECODER | |
LodePNGDecoderSettings decoder; /*the decoding settings*/ | |
#endif /*LODEPNG_COMPILE_DECODER*/ | |
#ifdef LODEPNG_COMPILE_ENCODER | |
LodePNGEncoderSettings encoder; /*the encoding settings*/ | |
#endif /*LODEPNG_COMPILE_ENCODER*/ | |
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*/ | |
void lodepng_state_init(LodePNGState* state); | |
void lodepng_state_cleanup(LodePNGState* state); | |
void lodepng_state_copy(LodePNGState* dest, const LodePNGState* source); | |
#endif /* defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER) */ | |
#ifdef LODEPNG_COMPILE_DECODER | |
/* | |
Same as lodepng_decode_memory, but uses a LodePNGState to allow custom settings and | |
getting much more information about the PNG image and color mode. | |
*/ | |
unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h, | |
LodePNGState* state, | |
const unsigned char* in, size_t insize); | |
/* | |
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 | |
information is placed in the info_png field of the LodePNGState. | |
*/ | |
unsigned lodepng_inspect(unsigned* w, unsigned* h, | |
LodePNGState* state, | |
const unsigned char* in, size_t insize); | |
#endif /*LODEPNG_COMPILE_DECODER*/ | |
#ifdef LODEPNG_COMPILE_ENCODER | |
/*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/ | |
unsigned lodepng_encode(unsigned char** out, size_t* outsize, | |
const unsigned char* image, unsigned w, unsigned h, | |
LodePNGState* state); | |
#endif /*LODEPNG_COMPILE_ENCODER*/ | |
/* | |
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 | |
*/ | |
/* | |
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*/ | |
void lodepng_chunk_type(char type[5], const unsigned char* chunk); | |
/*check if the type is the given type*/ | |
unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type); | |
/*0: it's one of the critical chunk types, 1: it's an ancillary chunk (see PNG standard)*/ | |
unsigned char lodepng_chunk_ancillary(const unsigned char* chunk); | |
/*0: public, 1: private (see PNG standard)*/ | |
unsigned char lodepng_chunk_private(const unsigned char* chunk); | |
/*0: the chunk is unsafe to copy, 1: the chunk is safe to copy (see PNG standard)*/ | |
unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk); | |
/*get pointer to the data of the chunk, where the input points to the header of the chunk*/ | |
unsigned char* lodepng_chunk_data(unsigned char* chunk); | |
const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk); | |
/*returns 0 if the crc is correct, 1 if it's incorrect (0 for OK as usual!)*/ | |
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); | |
/* | |
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. | |
Returns error code (0 if it went ok) | |
*/ | |
unsigned lodepng_chunk_append(unsigned char** out, size_t* outlength, 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. | |
Returne error code (0 if it went ok) | |
*/ | |
unsigned lodepng_chunk_create(unsigned char** out, size_t* outlength, unsigned length, | |
const char* type, const unsigned char* data); | |
/*Calculate CRC32 of buffer*/ | |
unsigned lodepng_crc32(const unsigned char* buf, size_t len); | |
#endif /*LODEPNG_COMPILE_PNG*/ | |
#ifdef LODEPNG_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 LODEPNG_COMPILE_DECODER | |
/*Inflate a buffer. Inflate is the decompression step of deflate. Out buffer must be freed after use.*/ | |
unsigned lodepng_inflate(unsigned char** out, size_t* outsize, | |
const unsigned char* in, size_t insize, | |
const LodePNGDecompressSettings* 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. | |
*/ | |
unsigned lodepng_zlib_decompress(unsigned char** out, size_t* outsize, | |
const unsigned char* in, size_t insize, | |
const LodePNGDecompressSettings* settings); | |
#endif /*LODEPNG_COMPILE_DECODER*/ | |
#ifdef LODEPNG_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. | |
*/ | |
unsigned lodepng_zlib_compress(unsigned char** out, size_t* outsize, | |
const unsigned char* in, size_t insize, | |
const LodePNGCompressSettings* settings); | |
/* | |
Find length-limited Huffman code for given frequencies. This function is in the | |
public interface only for tests, it's used internally by lodepng_deflate. | |
*/ | |
unsigned lodepng_huffman_code_lengths(unsigned* lengths, const unsigned* frequencies, | |
size_t numcodes, unsigned maxbitlen); | |
/*Compress a buffer with deflate. See RFC 1951. Out buffer must be freed after use.*/ | |
unsigned lodepng_deflate(unsigned char** out, size_t* outsize, | |
const unsigned char* in, size_t insize, | |
const LodePNGCompressSettings* settings); | |
#endif /*LODEPNG_COMPILE_ENCODER*/ | |
#endif /*LODEPNG_COMPILE_ZLIB*/ | |
#ifdef LODEPNG_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) | |
*/ | |
unsigned lodepng_load_file(unsigned char** out, size_t* 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) | |
*/ | |
unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const char* filename); | |
#endif /*LODEPNG_COMPILE_DISK*/ | |
#ifdef LODEPNG_COMPILE_CPP | |
/* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */ | |
namespace lodepng | |
{ | |
#ifdef LODEPNG_COMPILE_PNG | |
class State : public LodePNGState | |
{ | |
public: | |
State(); | |
State(const State& other); | |
virtual ~State(); | |
State& operator=(const State& other); | |
}; | |
#ifdef LODEPNG_COMPILE_DECODER | |
/* 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); | |
unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h, | |
State& state, | |
const std::vector<unsigned char>& in); | |
#endif /*LODEPNG_COMPILE_DECODER*/ | |
#ifdef LODEPNG_COMPILE_ENCODER | |
/* 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); | |
unsigned encode(std::vector<unsigned char>& out, | |
const std::vector<unsigned char>& in, unsigned w, unsigned h, | |
State& state); | |
#endif /*LODEPNG_COMPILE_ENCODER*/ | |
#ifdef LODEPNG_COMPILE_DISK | |
/* | |
Load a file from disk into an std::vector. | |
return value: error code (0 means ok) | |
*/ | |
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. | |
*/ | |
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 */ | |
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 */ | |
unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in, | |
const LodePNGDecompressSettings& settings = lodepng_default_decompress_settings); | |
#endif /* LODEPNG_COMPILE_DECODER */ | |
#ifdef LODEPNG_COMPILE_ENCODER | |
/* 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 */ | |
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_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 | |
[ ] read all public PNG chunk types (but never let the color profile and gamma ones touch RGB values) | |
[ ] 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 warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ... | |
[ ] 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 | |
*/ | |
#endif /*LODEPNG_H inclusion guard*/ | |
/* | |
LodePNG Documentation | |
--------------------- | |
0. table of contents | |
-------------------- | |
1. about | |
1.1. supported features | |
1.2. features not supported | |
2. C and C++ version | |
3. security | |
4. decoding | |
5. encoding | |
6. color conversions | |
6.1. PNG color types | |
6.2. color conversions | |
6.3. padding bits | |
6.4. A note about 16-bits per channel and endianness | |
7. error values | |
8. chunks and PNG editing | |
9. compiler support | |
10. examples | |
10.1. decoder C++ example | |
10.2. decoder C example | |
11. state settings reference | |
12. changes | |
13. contact information | |
1. about | |
-------- | |
PNG is a file format to store raster images losslessly with good compression, | |
supporting different color types and alpha channel. | |
LodePNG is a PNG codec according to the Portable Network Graphics (PNG) | |
Specification (Second Edition) - W3C Recommendation 10 November 2003. | |
The specifications used are: | |
*) Portable Network Graphics (PNG) Specification (Second Edition): | |
http://www.w3.org/TR/2003/REC-PNG-20031110 | |
*) RFC 1950 ZLIB Compressed Data Format version 3.3: | |
http://www.gzip.org/zlib/rfc-zlib.html | |
*) RFC 1951 DEFLATE Compressed Data Format Specification ver 1.3: | |
http://www.gzip.org/zlib/rfc-deflate.html | |
The most recent version of LodePNG can currently be found at | |
http://lodev.org/lodepng/ | |
LodePNG works both in C (ISO C90) and C++, with a C++ wrapper that adds | |
extra functionality. | |
LodePNG exists out of two files: | |
-lodepng.h: the header file for both C and C++ | |
-lodepng.c(pp): give it the name lodepng.c or lodepng.cpp (or .cc) depending on your usage | |
If you want to start using LodePNG right away without reading this doc, get the | |
examples from the LodePNG website to see how to use it in code, or check the | |
smaller examples in chapter 13 here. | |
LodePNG is simple but only supports the basic requirements. To achieve | |
simplicity, the following design choices were made: There are no dependencies | |
on any external library. There are functions to decode and encode a PNG with | |
a single function call, and extended versions of these functions taking a | |
LodePNGState struct allowing to specify or get more information. By default | |
the colors of the raw image are always RGB or RGBA, no matter what color type | |
the PNG file uses. To read and write files, there are simple functions to | |
convert the files to/from buffers in memory. | |
This all makes LodePNG suitable for loading textures in games, demos and small | |
programs, ... It's less suitable for full fledged image editors, loading PNGs | |
over network (it requires all the image data to be available before decoding can | |
begin), life-critical systems, ... | |
1.1. supported features | |
----------------------- | |
The following features are supported by the decoder: | |
*) decoding of PNGs with any color type, bit depth and interlace mode, to a 24- or 32-bit color raw image, | |
or the same color type as the PNG | |
*) encoding of PNGs, from any raw image to 24- or 32-bit color, or the same color type as the raw image | |
*) Adam7 interlace and deinterlace for any color type | |
*) loading the image from harddisk or decoding it from a buffer from other sources than harddisk | |
*) support for alpha channels, including RGBA color model, translucent palettes and color keying | |
*) zlib decompression (inflate) | |
*) zlib compression (deflate) | |
*) CRC32 and ADLER32 checksums | |
*) 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: | |
IHDR: header information | |
PLTE: color palette | |
IDAT: pixel data | |
IEND: the final chunk | |
tRNS: transparency for palettized images | |
tEXt: textual information | |
zTXt: compressed textual information | |
iTXt: international textual information | |
bKGD: suggested background color | |
pHYs: physical dimensions | |
tIME: modification time | |
1.2. features not supported | |
--------------------------- | |
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. | |
2. C and C++ version | |
-------------------- | |
The C version uses buffers allocated with alloc that you need to free() | |
yourself. You need to use init and cleanup functions for each struct whenever | |
using a struct from the C version to avoid exploits and memory leaks. | |
The C++ version has extra functions with std::vectors in the interface and the | |
lodepng::State class which is a LodePNGState with constructor and destructor. | |
These files work without modification for both C and C++ compilers because all | |
the additional C++ code is in "#ifdef __cplusplus" blocks that make C-compilers | |
ignore it, and the C code is made to compile both with strict ISO C90 and C++. | |
To use the C++ version, you need to rename the source file to lodepng.cpp | |
(instead of lodepng.c), and compile it with a C++ compiler. | |
To use the C version, you need to rename the source file to lodepng.c (instead | |
of lodepng.cpp), and compile it with a C compiler. | |
3. Security | |
----------- | |
Even if carefully designed, it's always possible that LodePNG contains possible | |
exploits. If you discover one, please let me know, and it will be fixed. | |
When using LodePNG, care has to be taken with the C version of LodePNG, as well | |
as the C-style structs when working with C++. The following conventions are used | |
for all C-style structs: | |
-if a struct has a corresponding init function, always call the init function when making a new one | |
-if a struct has a corresponding cleanup function, call it before the struct disappears to avoid memory leaks | |
-if a struct has a corresponding copy function, use the copy function instead of "=". | |
The destination must also be inited already. | |
4. Decoding | |
----------- | |
Decoding converts a PNG compressed image to a raw pixel buffer. | |
Most documentation on using the decoder is at its declarations in the header | |
above. For C, simple decoding can be done with functions such as | |
lodepng_decode32, and more advanced decoding can be done with the struct | |
LodePNGState and lodepng_decode. For C++, all decoding can be done with the | |
various lodepng::decode functions, and lodepng::State can be used for advanced | |
features. | |
When using the LodePNGState, it uses the following fields for decoding: | |
*) LodePNGInfo info_png: it stores extra information about the PNG (the input) in here | |
*) LodePNGColorMode info_raw: here you can say what color mode of the raw image (the output) you want to get | |
*) LodePNGDecoderSettings decoder: you can specify a few extra settings for the decoder to use | |
LodePNGInfo info_png | |
-------------------- | |
After decoding, this contains extra information of the PNG image, except the actual | |
pixels, width and height because these are already gotten directly from the decoder | |
functions. | |
It contains for example the original color type of the PNG image, text comments, | |
suggested background color, etc... More details about the LodePNGInfo struct are | |
at its declaration documentation. | |
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 | |
a palette with missing colors. | |
By default, 32-bit color is used for the result. | |
LodePNGDecoderSettings decoder | |
------------------------------ | |
The settings can be used to ignore the errors created by invalid CRC and Adler32 | |
chunks, and to disable the decoding of tEXt chunks. | |
There's also a setting color_convert, true by default. If false, no conversion | |
is done, the resulting data will be as it was in the PNG (after decompression) | |
and you'll have to puzzle the colors of the pixels together yourself using the | |
color type information in the LodePNGInfo. | |
5. Encoding | |
----------- | |
Encoding converts a raw pixel buffer to a PNG compressed image. | |
Most documentation on using the encoder is at its declarations in the header | |
above. For C, simple encoding can be done with functions such as | |
lodepng_encode32, and more advanced decoding can be done with the struct | |
LodePNGState and lodepng_encode. For C++, all encoding can be done with the | |
various lodepng::encode functions, and lodepng::State can be used for advanced | |
features. | |
Like the decoder, the encoder can also give errors. However it gives less errors | |
since the encoder input is trusted, the decoder input (a PNG image that could | |
be forged by anyone) is not trusted. | |
When using the LodePNGState, it uses the following fields for encoding: | |
*) LodePNGInfo info_png: here you specify how you want the PNG (the output) to be. | |
*) LodePNGColorMode info_raw: here you say what color type of the raw image (the input) has | |
*) LodePNGEncoderSettings encoder: you can specify a few settings for the encoder to use | |
LodePNGInfo info_png | |
-------------------- | |
When encoding, you use this the opposite way as when decoding: for encoding, | |
you fill in the values you want the PNG to have before encoding. By default it's | |
not needed to specify a color type for the PNG since it's automatically chosen, | |
but it's possible to choose it yourself given the right settings. | |
The encoder will not always exactly match the LodePNGInfo struct you give, | |
it tries as close as possible. Some things are ignored by the encoder. The | |
encoder uses, for example, the following settings from it when applicable: | |
colortype and bitdepth, text chunks, time chunk, the color key, the palette, the | |
background color, the interlace method, unknown chunks, ... | |
When encoding to a PNG with colortype 3, the encoder will generate a PLTE chunk. | |
If the palette contains any colors for which the alpha channel is not 255 (so | |
there are translucent colors in the palette), it'll add a tRNS chunk. | |
LodePNGColorMode info_raw | |
------------------------- | |
You specify the color type of the raw image that you give to the input here, | |
including a possible transparent color key and palette you happen to be using in | |
your raw image data. | |
By default, 32-bit color is assumed, meaning your input has to be in RGBA | |
format with 4 bytes (unsigned chars) per pixel. | |
LodePNGEncoderSettings encoder | |
------------------------------ | |
The following settings are supported (some are in sub-structs): | |
*) auto_convert: when this option is enabled, the encoder will | |
automatically choose the smallest possible color mode (including color key) that | |
can encode the colors of all pixels without information loss. | |
*) btype: the block type for LZ77. 0 = uncompressed, 1 = fixed huffman tree, | |
2 = dynamic huffman tree (best compression). Should be 2 for proper | |
compression. | |
*) use_lz77: whether or not to use LZ77 for compressed block types. Should be | |
true for proper compression. | |
*) windowsize: the window size used by the LZ77 encoder (1 - 32768). Has value | |
2048 by default, but can be set to 32768 for better, but slow, compression. | |
*) force_palette: if colortype is 2 or 6, you can make the encoder write a PLTE | |
chunk if force_palette is true. This can used as suggested palette to convert | |
to by viewers that don't support more than 256 colors (if those still exist) | |
*) add_id: add text chunk "Encoder: LodePNG <version>" to the image. | |
*) text_compression: default 1. If 1, it'll store texts as zTXt instead of tEXt chunks. | |
zTXt chunks use zlib compression on the text. This gives a smaller result on | |
large texts but a larger result on small texts (such as a single program name). | |
It's all tEXt or all zTXt though, there's no separate setting per text yet. | |
6. color conversions | |
-------------------- | |
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. | |
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 | |
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 | |
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 | |
is easy, but there are multiple ways if you want to give some channels more | |
weight). | |
By default, when decoding, you get the raw image in 32-bit RGBA or 24-bit RGB | |
color, no matter what color type the PNG has. And by default when encoding, | |
LodePNG automatically picks the best color model for the output PNG, and expects | |
the input image to be 32-bit RGBA or 24-bit RGB. So, unless you want to control | |
the color format of the images yourself, you can skip this chapter. | |
6.1. PNG color types | |
-------------------- | |
A PNG image can have many color types, ranging from 1-bit color to 64-bit color, | |
as well as palettized color modes. After the zlib decompression and unfiltering | |
in the PNG image is done, the raw pixel data will have that color type and thus | |
a certain amount of bits per pixel. If you want the output raw image after | |
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 | |
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 | |
6: RGBA, bit depths 8 and 16 | |
Bit depth is the amount of bits per pixel per color channel. So the total amount | |
of bits per pixel is: amount of channels * bitdepth. | |
6.2. color conversions | |
---------------------- | |
As explained in the sections about the encoder and decoder, you can specify | |
color types and bit depths in info_png and info_raw to change the default | |
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 colortype and bitdepth of the simple decoding function. | |
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 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 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 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 | |
-the encoder converts from raw image to PNG | |
-the colortype and bitdepth in LodePNGColorMode info_raw, are those of the raw image | |
-the colortype and bitdepth in the color field of LodePNGInfo info_png, are those of the PNG | |
-when encoding, the color type in LodePNGInfo is ignored if auto_convert | |
is enabled, it is automatically generated instead | |
-when decoding, the color type in LodePNGInfo is set by the decoder to that of the original | |
PNG image, but it can be ignored since the raw image has the color type you requested instead | |
-if the color type of the LodePNGColorMode and PNG image aren't the same, a conversion | |
between the color types is done if the color types are supported. If it is not | |
supported, an error is returned. If the types are the same, no conversion is done. | |
-even though some conversions aren't supported, LodePNG supports loading PNGs from any | |
colortype and saving PNGs to any colortype, sometimes it just requires preparing | |
the raw image correctly before encoding. | |
-both encoder and decoder use the same color converter. | |
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 | |
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 | |
-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 (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 | |
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 | |
----------------- | |
In the PNG file format, if a less than 8-bit per pixel color type is used and the scanlines | |
have a bit amount that isn't a multiple of 8, then padding bits are used so that each | |
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, | |
not the first bit of a new byte. | |
6.4. A note about 16-bits per channel and endianness | |
---------------------------------------------------- | |
LodePNG uses unsigned char arrays for 16-bit per channel colors too, just like | |
for any other color format. The 16-bit values are stored in big endian (most | |
significant byte first) in these arrays. This is the opposite order of the | |
little endian used by x86 CPU's. | |
LodePNG always uses big endian because the PNG file format does so internally. | |
Conversions to other formats than PNG uses internally are not supported by | |
LodePNG on purpose, there are myriads of formats, including endianness of 16-bit | |
colors, the order in which you store R, G, B and A, and so on. Supporting and | |
converting to/from all that is outside the scope of LodePNG. | |
This may mean that, depending on your use case, you may want to convert the big | |
endian output of LodePNG to little endian with a for loop. This is certainly not | |
always needed, many applications and libraries support big endian 16-bit colors | |
anyway, but it means you cannot simply cast the unsigned char* buffer to an | |
unsigned short* buffer on x86 CPUs. | |
7. error values | |
--------------- | |
All functions in LodePNG that return an error code, return 0 if everything went | |
OK, or a non-zero code if there was an error. | |
The meaning of the LodePNG error values can be retrieved with the function | |
lodepng_error_text: given the numerical error code, it returns a description | |
of the error in English as a string. | |
Check the implementation of lodepng_error_text to see the meaning of each code. | |
8. chunks and PNG editing | |
------------------------- | |
If you want to add extra chunks to a PNG you encode, or use LodePNG for a PNG | |
editor that should follow the rules about handling of unknown chunks, or if your | |
program is able to read other types of chunks than the ones handled by LodePNG, | |
then that's possible with the chunk functions of LodePNG. | |
A PNG chunk has the following layout: | |
4 bytes length | |
4 bytes type name | |
length bytes data | |
4 bytes CRC | |
8.1. iterating through chunks | |
----------------------------- | |
If you have a buffer containing the PNG image data, then the first chunk (the | |
IHDR chunk) starts at byte number 8 of that buffer. The first 8 bytes are the | |
signature of the PNG and are not part of a chunk. But if you start at byte 8 | |
then you have a chunk, and can check the following things of it. | |
NOTE: none of these functions check for memory buffer boundaries. To avoid | |
exploits, always make sure the buffer contains all the data of the chunks. | |
When using lodepng_chunk_next, make sure the returned value is within the | |
allocated memory. | |
unsigned lodepng_chunk_length(const unsigned char* chunk): | |
Get the length of the chunk's data. The total chunk length is this length + 12. | |
void lodepng_chunk_type(char type[5], const unsigned char* chunk): | |
unsigned char lodepng_chunk_type_equals(const unsigned char* chunk, const char* type): | |
Get the type of the chunk or compare if it's a certain type | |
unsigned char lodepng_chunk_critical(const unsigned char* chunk): | |
unsigned char lodepng_chunk_private(const unsigned char* chunk): | |
unsigned char lodepng_chunk_safetocopy(const unsigned char* chunk): | |
Check if the chunk is critical in the PNG standard (only IHDR, PLTE, IDAT and IEND are). | |
Check if the chunk is private (public chunks are part of the standard, private ones not). | |
Check if the chunk is safe to copy. If it's not, then, when modifying data in a critical | |
chunk, unsafe to copy chunks of the old image may NOT be saved in the new one if your | |
program doesn't handle that type of unknown chunk. | |
unsigned char* lodepng_chunk_data(unsigned char* chunk): | |
const unsigned char* lodepng_chunk_data_const(const unsigned char* chunk): | |
Get a pointer to the start of the data of the chunk. | |
unsigned lodepng_chunk_check_crc(const unsigned char* chunk): | |
void lodepng_chunk_generate_crc(unsigned char* chunk): | |
Check if the crc is correct or generate a correct one. | |
unsigned char* lodepng_chunk_next(unsigned char* chunk): | |
const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk): | |
Iterate to the next chunk. This works if you have a buffer with consecutive chunks. Note that these | |
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, | |
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 | |
function creates a new chunk with the given parameters and appends it. Type is the 4-letter | |
name of the chunk. | |
8.2. chunks in info_png | |
----------------------- | |
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 | |
standard forces to keep the ordering of unknown chunks compared to the critical | |
chunks, but does not force any other ordering rules. | |
info_png.unknown_chunks_data[0] is the chunks before PLTE | |
info_png.unknown_chunks_data[1] is the chunks after PLTE, before IDAT | |
info_png.unknown_chunks_data[2] is the chunks after IDAT | |
The chunks in these 3 buffers can be iterated through and read by using the same | |
way described in the previous subchapter. | |
When using the decoder to decode a PNG, you can make it store all unknown chunks | |
if you set the option settings.remember_unknown_chunks to 1. By default, this | |
option is off (0). | |
The encoder will always encode unknown chunks that are stored in the info_png. | |
If you need it to add a particular chunk that isn't known by LodePNG, you can | |
use lodepng_chunk_append or lodepng_chunk_create to the chunk data in | |
info_png.unknown_chunks_data[x]. | |
Chunks that are known by LodePNG should not be added in that way. E.g. to make | |
LodePNG add a bKGD chunk, set background_defined to true and add the correct | |
parameters there instead. | |
9. compiler support | |
------------------- | |
No libraries other than the current standard C library are needed to compile | |
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. | |
Make sure that LodePNG is compiled with the same compiler of the same version | |
and with the same settings as the rest of the program, or the interfaces with | |
std::vectors and std::strings in C++ can be incompatible. | |
CHAR_BITS must be 8 or higher, because LodePNG uses unsigned chars for octets. | |
*) gcc and g++ | |
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. | |
*) Clang | |
Fully supported and warning-free. | |
*) Mingw | |
The Mingw compiler (a port of gcc for Windows) should be fully supported by | |
LodePNG. | |
*) Visual Studio and Visual C++ Express Edition | |
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". | |
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. | |
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 gcc and LLVM for Macintosh, both for | |
C and C++. | |
*) Other Compilers | |
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 complient. | |
10. examples | |
------------ | |
This decoder example shows the most basic usage of LodePNG. More complex | |
examples can be found on the LodePNG website. | |
10.1. decoder C++ example | |
------------------------- | |
#include "lodepng.h" | |
#include <iostream> | |
int main(int argc, char *argv[]) | |
{ | |
const char* filename = argc > 1 ? argv[1] : "test.png"; | |
//load and decode | |
std::vector<unsigned char> image; | |
unsigned width, height; | |
unsigned error = lodepng::decode(image, width, height, filename); | |
//if there's an error, display it | |
if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl; | |
//the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ... | |
} | |
10.2. decoder C example | |
----------------------- | |
#include "lodepng.h" | |
int main(int argc, char *argv[]) | |
{ | |
unsigned error; | |
unsigned char* image; | |
size_t width, height; | |
const char* filename = argc > 1 ? argv[1] : "test.png"; | |
error = lodepng_decode32_file(&image, &width, &height, filename); | |
if(error) printf("decoder error %u: %s\n", error, lodepng_error_text(error)); | |
/ * use image here * / | |
free(image); | |
return 0; | |
} | |
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.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 | |
yyyymmdd. | |
Some changes aren't backwards compatible. Those are indicated with a (!) | |
symbol. | |
*) 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. | |
*) 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_" | |
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. | |
(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 | |
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 | |
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 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. | |
*) 8 sep 2011: lz77 encoder lazy matching instead of greedy matching. | |
*) 23 aug 2011: tweaked the zlib compression parameters after benchmarking. | |
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. | |
*) 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. | |
*) 11 dec 2010: encoding is made faster, based on suggestion by Peter Eastman | |
to optimize long sequences of zeros. | |
*) 13 nov 2010: added LodePNG_InfoColor_hasPaletteAlpha and | |
LodePNG_InfoColor_canHaveAlpha functions for convenience. | |
*) 7 nov 2010: added LodePNG_error_text function to get error code description. | |
*) 30 okt 2010: made decoding slightly faster | |
*) 26 okt 2010: (!) changed some C function and struct names (more consistent). | |
Reorganized the documentation and the declaration order in the header. | |
*) 08 aug 2010: only changed some comments and external samples. | |
*) 05 jul 2010: fixed bug thanks to warnings in the new gcc version. | |
*) 14 mar 2010: fixed bug where too much memory was allocated for char buffers. | |
*) 02 sep 2008: fixed bug where it could create empty tree that linux apps could | |
read by ignoring the problem but windows apps couldn't. | |
*) 06 jun 2008: added more error checks for out of memory cases. | |
*) 26 apr 2008: added a few more checks here and there to ensure more safety. | |
*) 06 mar 2008: crash with encoding of strings fixed | |
*) 02 feb 2008: support for international text chunks added (iTXt) | |
*) 23 jan 2008: small cleanups, and #defines to divide code in sections | |
*) 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 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 | |
C++ wrapper around this provides an interface almost identical to before. | |
Having LodePNG be pure ISO C90 makes it more portable. The C and C++ code | |
are together in these files but it works both for C and C++ compilers. | |
*) 29 dec 2007: (!) changed most integer types to unsigned int + other tweaks | |
*) 30 aug 2007: bug fixed which makes this Borland C++ compatible | |
*) 09 aug 2007: some VS2005 warnings removed again | |
*) 21 jul 2007: deflate code placed in new namespace separate from zlib code | |
*) 08 jun 2007: fixed bug with 2- and 4-bit color, and small interlaced images | |
*) 04 jun 2007: improved support for Visual Studio 2005: crash with accessing | |
invalid std::vector element [0] fixed, and level 3 and 4 warnings removed | |
*) 02 jun 2007: made the encoder add a tag with version by default | |
*) 27 may 2007: zlib and png code separated (but still in the same file), | |
simple encoder/decoder functions added for more simple usage cases | |
*) 19 may 2007: minor fixes, some code cleaning, new error added (error 69), | |
moved some examples from here to lodepng_examples.cpp | |
*) 12 may 2007: palette decoding bug fixed | |
*) 24 apr 2007: changed the license from BSD to the zlib license | |
*) 11 mar 2007: very simple addition: ability to encode bKGD chunks. | |
*) 04 mar 2007: (!) tEXt chunk related fixes, and support for encoding | |
palettized PNG images. Plus little interface change with palette and texts. | |
*) 03 mar 2007: Made it encode dynamic Huffman shorter with repeat codes. | |
Fixed a bug where the end code of a block had length 0 in the Huffman tree. | |
*) 26 feb 2007: Huffman compression with dynamic trees (BTYPE 2) now implemented | |
and supported by the encoder, resulting in smaller PNGs at the output. | |
*) 27 jan 2007: Made the Adler-32 test faster so that a timewaste is gone. | |
*) 24 jan 2007: gave encoder an error interface. Added color conversion from any | |
greyscale type to 8-bit greyscale with or without alpha. | |
*) 21 jan 2007: (!) Totally changed the interface. It allows more color types | |
to convert to and is more uniform. See the manual for how it works now. | |
*) 07 jan 2007: Some cleanup & fixes, and a few changes over the last days: | |
encode/decode custom tEXt chunks, separate classes for zlib & deflate, and | |
at last made the decoder give errors for incorrect Adler32 or Crc. | |
*) 01 jan 2007: Fixed bug with encoding PNGs with less than 8 bits per channel. | |
*) 29 dec 2006: Added support for encoding images without alpha channel, and | |
cleaned out code as well as making certain parts faster. | |
*) 28 dec 2006: Added "Settings" to the encoder. | |
*) 26 dec 2006: The encoder now does LZ77 encoding and produces much smaller files now. | |
Removed some code duplication in the decoder. Fixed little bug in an example. | |
*) 09 dec 2006: (!) Placed output parameters of public functions as first parameter. | |
Fixed a bug of the decoder with 16-bit per color. | |
*) 15 okt 2006: Changed documentation structure | |
*) 09 okt 2006: Encoder class added. It encodes a valid PNG image from the | |
given image buffer, however for now it's not compressed. | |
*) 08 sep 2006: (!) Changed to interface with a Decoder class | |
*) 30 jul 2006: (!) LodePNG_InfoPng , width and height are now retrieved in different | |
way. Renamed decodePNG to decodePNGGeneric. | |
*) 29 jul 2006: (!) Changed the interface: image info is now returned as a | |
struct of type LodePNG::LodePNG_Info, instead of a vector, which was a bit clumsy. | |
*) 28 jul 2006: Cleaned the code and added new error checks. | |
Corrected terminology "deflate" into "inflate". | |
*) 23 jun 2006: Added SDL example in the documentation in the header, this | |
example allows easy debugging by displaying the PNG and its transparency. | |
*) 22 jun 2006: (!) Changed way to obtain error value. Added | |
loadFile function for convenience. Made decodePNG32 faster. | |
*) 21 jun 2006: (!) Changed type of info vector to unsigned. | |
Changed position of palette in info vector. Fixed an important bug that | |
happened on PNGs with an uncompressed block. | |
*) 16 jun 2006: Internally changed unsigned into unsigned where | |
needed, and performed some optimizations. | |
*) 07 jun 2006: (!) Renamed functions to decodePNG and placed them | |
in LodePNG namespace. Changed the order of the parameters. Rewrote the | |
documentation in the header. Renamed files to lodepng.cpp and lodepng.h | |
*) 22 apr 2006: Optimized and improved some code | |
*) 07 sep 2005: (!) Changed to std::vector interface | |
*) 12 aug 2005: Initial release (C++, decoder only) | |
13. contact information | |
----------------------- | |
Feel free to contact me with suggestions, problems, comments, ... concerning | |
LodePNG. If you encounter a PNG image that doesn't work properly with this | |
decoder, feel free to send it and I'll use it to find and fix the problem. | |
My email address is (puzzle the account and domain together with an @ symbol): | |
Domain: gmail dot com. | |
Account: lode dot vandevenne. | |
Copyright (c) 2005-2016 Lode Vandevenne | |
*/#pragma once |