/*

LodePNG version 20140823

Copyright (c) 2005-2014 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*/

#ifdef __cplusplus

#include <vector>

#include <string>

#endif /*__cplusplus*/

/*

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.

*/

/*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

#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*/

#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,

                         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 minumum 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; /*if true, image is not opaque. Only if true and alpha is false, color key is possible.*/

  unsigned short key_r; /*these values are always in 16-bit bitdepth in the profile*/

  unsigned short key_g;

  unsigned short key_b;

  unsigned alpha; /*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 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;

} 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

*/

/*get the length of the data of the chunk. Total chunk length has 12 bytes more.*/

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*/

/*

TODO:

[.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often

[.] check compatibility with vareous compilers  - done but needs to be redone for every newer version

[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 option to choose if the raw image with non multiple of 8 bits per scanline should have padding bits or not

[ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes

*/

#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. changes

  12. 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.