EmbeddedArtists AB
Graphical demo for the LPC4088 Experiment Base Board with one of the Display Expansion Kits. This program decodes decodes and shows two png images.
Diff: lodepng.h
- Revision:
- 0:b567d56a59d7
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/lodepng.h Fri Oct 03 13:30:09 2014 +0000
@@ -0,0 +1,1725 @@
+/*
+LodePNG version 20131222
+
+Copyright (c) 2005-2013 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*/
+
+
+// Settings modified by Embedded Artists
+#define LODEPNG_NO_COMPILE_ENCODER
+#define LODEPNG_NO_COMPILE_DISK
+#define LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS
+#define LODEPNG_NO_COMPILE_ERROR_TEXT
+#define LODEPNG_NO_COMPILE_CPP
+
+
+/*
+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
+/*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_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.*/
+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.*/
+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. Typical 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)
+The fix_png value works as described in struct LodePNGDecoderSettings.
+Note: for 16-bit per channel colors, uses big endian format like PNG does.
+*/
+unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
+ LodePNGColorMode* mode_out, const LodePNGColorMode* mode_in,
+ unsigned w, unsigned h, unsigned fix_png);
+
+#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*/
+ /*
+ The fix_png setting, if 1, makes the decoder tolerant towards some PNG images
+ that do not correctly follow the PNG specification. This only supports errors
+ that are fixable, were found in images that are actually used on the web, and
+ are silently tolerated by other decoders as well. Currently only one such fix
+ is implemented: if a palette index is out of bounds given the palette size,
+ interpret it as opaque black.
+ By default this value is 0, which makes it stop with an error on such images.
+ */
+ unsigned fix_png;
+ unsigned 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;
+
+/*automatically use color type with less bits per pixel if losslessly possible. Default: LAC_AUTO*/
+typedef enum LodePNGAutoConvert
+{
+ LAC_NO, /*use color type user requested*/
+ LAC_ALPHA, /*use color type user requested, but if only opaque pixels and RGBA or grey+alpha, use RGB or grey*/
+ LAC_AUTO, /*use PNG color type that can losslessly represent the uncompressed image the smallest possible*/
+ /*
+ like AUTO, but do not choose 1, 2 or 4 bit per pixel types.
+ sometimes a PNG image compresses worse if less than 8 bits per pixels.
+ */
+ LAC_AUTO_NO_NIBBLES,
+ /*
+ like AUTO, but never choose palette color type. For small images, encoding
+ the palette may take more bytes than what is gained. Note that AUTO also
+ already prevents encoding the palette for extremely small images, but that may
+ not be sufficient because due to the compression it cannot predict when to
+ switch.
+ */
+ LAC_AUTO_NO_PALETTE,
+ LAC_AUTO_NO_NIBBLES_NO_PALETTE
+} LodePNGAutoConvert;
+
+
+/*
+Automatically chooses color type that gives smallest amount of bits in the
+output image, e.g. grey if there are only greyscale pixels, palette if there
+are less than 256 colors, ...
+The auto_convert parameter allows limiting it to not use palette, ...
+*/
+unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out,
+ const unsigned char* image, unsigned w, unsigned h,
+ const LodePNGColorMode* mode_in,
+ LodePNGAutoConvert auto_convert);
+
+/*Settings for the encoder.*/
+typedef struct LodePNGEncoderSettings
+{
+ LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/
+
+ LodePNGAutoConvert auto_convert; /*how to automatically choose output PNG color type, if at all*/
+
+ /*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
+*/
+
+/*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*/
+
+#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. If the vector is empty, then either
+the file doesn't exist or is an empty file.
+*/
+void load_file(std::vector<unsigned char>& buffer, const std::string& filename);
+
+/*
+Save the binary data in an std::vector to a file on disk. The file is overwritten
+without warning.
+*/
+void save_file(const std::vector<unsigned char>& buffer, const std::string& filename);
+#endif //LODEPNG_COMPILE_DISK
+#endif //LODEPNG_COMPILE_PNG
+
+#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 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.
+
+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 of the simple function of LodePNG you're using.
+
+If, when encoding, you use another color type than the default in the input
+image, you need to specify its color type and bit depth in the LodePNGColorMode
+of the raw image, or use the parameters of the simplefunction of LodePNG you're
+using.
+
+If, when encoding, you don't want LodePNG to choose the output PNG color type
+but control it yourself, you need to set auto_convert in the encoder settings
+to LAC_NONE, and specify the color type you want in the LodePNGInfo of the
+encoder.
+
+If you do any of the above, LodePNG may need to do a color conversion, which
+follows the rules below, and may sometimes not be allowed.
+
+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:
+-In the encoder, you can make it save a PNG with any color type by giving the
+raw color mode and LodePNGInfo the same color mode, and setting auto_convert to
+LAC_NO.
+-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.
+
+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.
+
+*) Mingw
+
+The Mingw compiler (a port of gcc) for Windows is fully supported by LodePNG.
+
+*) Visual Studio 2005 and up, Visual C++ Express Edition 2005 and up
+
+Visual Studio may give warnings about 'fopen' being deprecated. A multiplatform library
+can't support the proposed Visual Studio alternative however, so LodePNG keeps using
+fopen. If you don't want to see the deprecated warnings, put this on top of lodepng.h
+before the inclusions:
+#define _CRT_SECURE_NO_DEPRECATE
+
+Other than the above warnings, LodePNG should be warning-free with warning
+level 3 (W3). Warning level 4 (W4) will give warnings about integer conversions.
+I'm not planning to resolve these warnings. To get rid of them, let Visual
+Studio use warning level W3 for lodepng.cpp only: right click lodepng.cpp,
+Properties, C/C++, General, Warning Level: Level 3 (/W3).
+
+Visual Studio may want "stdafx.h" files to be included in each source file and
+give an error "unexpected end of file while looking for precompiled header".
+That is not standard C++ and will not be added to the stock LodePNG. You can
+disable it for lodepng.cpp only by right clicking it, Properties, C/C++,
+Precompiled Headers, and set it to Not Using Precompiled Headers there.
+
+*) Visual Studio 6.0
+
+LodePNG support for Visual Studio 6.0 is not guaranteed because VS6 doesn't
+follow the C++ standard correctly.
+
+*) Comeau C/C++
+
+Vesion 20070107 compiles without problems on the Comeau C/C++ Online Test Drive
+at http://www.comeaucomputing.com/tryitout in both C90 and C++ mode.
+
+*) Compilers on Macintosh
+
+LodePNG has been reported to work both with the gcc and LLVM for Macintosh, both
+for C and C++.
+
+*) Other Compilers
+
+If you encounter problems on other compilers, feel free to let me know and I may
+try to fix it if the compiler is modern standards complient.
+
+
+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. 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.
+
+*) 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 shrinked 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 vareous 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)
+
+
+12. 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) 2005-2013 Lode Vandevenne
+*/