mirror of https://github.com/vitalif/openscad
1900 lines
86 KiB
C++
1900 lines
86 KiB
C++
#ifndef LODEPNG_H_
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#define LODEPNG_H_
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/*
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LodePNG version 20110908
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Copyright (c) 2005-2011 Lode Vandevenne
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source
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distribution.
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*/
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#ifndef LODEPNG_H
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#define LODEPNG_H
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#include <string.h> /*for size_t*/
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#ifdef __cplusplus
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#include <vector>
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#include <string>
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#endif /*__cplusplus*/
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/* ////////////////////////////////////////////////////////////////////////// */
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/* Code Sections */
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/* ////////////////////////////////////////////////////////////////////////// */
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/*
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The following #defines are used to create code sections. They can be disabled
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to disable code sections, which can give faster compile time and smaller binary.
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*/
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/*deflate&zlib encoder and deflate&zlib decoder.
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If this is disabled, you need to implement the dummy LodePNG_zlib_compress and
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LodePNG_zlib_decompress functions in the #else belonging to this #define in the
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source file.*/
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#define LODEPNG_COMPILE_ZLIB
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/*png encoder and png decoder*/
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#define LODEPNG_COMPILE_PNG
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/*deflate&zlib decoder and png decoder*/
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#define LODEPNG_COMPILE_DECODER
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/*deflate&zlib encoder and png encoder*/
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#define LODEPNG_COMPILE_ENCODER
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/*the optional built in harddisk file loading and saving functions*/
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#define LODEPNG_COMPILE_DISK
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/*any code or struct datamember related to chunks other than IHDR, IDAT, PLTE, tRNS, IEND*/
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#define LODEPNG_COMPILE_ANCILLARY_CHUNKS
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/*handling of unknown chunks*/
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#define LODEPNG_COMPILE_UNKNOWN_CHUNKS
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/*ability to convert error numerical codes to English text string*/
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#define LODEPNG_COMPILE_ERROR_TEXT
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/* ////////////////////////////////////////////////////////////////////////// */
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/* Simple Functions */
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/* ////////////////////////////////////////////////////////////////////////// */
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/*
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This are the simple C and C++ functions, which cover basic usage.
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Further on in the header file are the more advanced functions allowing custom behaviour.
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*/
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#ifdef LODEPNG_COMPILE_PNG
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/*constants for the PNG color types. "LCT" = "LodePNG Color Type"*/
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#define LCT_GREY 0 /*PNG color type greyscale*/
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#define LCT_RGB 2 /*PNG color type RGB*/
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#define LCT_PALETTE 3 /*PNG color type palette*/
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#define LCT_GREY_ALPHA 4 /*PNG color type greyscale with alpha*/
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#define LCT_RGBA 6 /*PNG color type RGB with alpha*/
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#ifdef LODEPNG_COMPILE_DECODER
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/*
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Converts PNG data in memory to raw pixel data.
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out: Output parameter. Pointer to buffer that will contain the raw pixel data.
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Its size is w * h * (bytes per pixel), bytes per pixel depends on colorType and bitDepth.
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Must be freed after usage with free(*out).
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w: Output parameter. Pointer to width of pixel data.
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h: Output parameter. Pointer to height of pixel data.
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in: Memory buffer with the PNG file.
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insize: size of the in buffer.
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colorType: the desired color type for the raw output image. See explanation on PNG color types.
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bitDepth: the desired bit depth for the raw output image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned LodePNG_decode(unsigned char** out, unsigned* w, unsigned* h,
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const unsigned char* in, size_t insize, unsigned colorType, unsigned bitDepth);
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/*Same as LodePNG_decode, but uses colorType = 6 and bitDepth = 8 by default (32-bit RGBA)*/
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unsigned LodePNG_decode32(unsigned char** out, unsigned* w, unsigned* h,
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const unsigned char* in, size_t insize);
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/*Same as LodePNG_decode, but uses colorType = 2 and bitDepth = 8 by default (24-bit RGB)*/
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unsigned LodePNG_decode24(unsigned char** out, unsigned* w, unsigned* h,
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const unsigned char* in, size_t insize);
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#ifdef LODEPNG_COMPILE_DISK
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/*
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Load PNG from disk, from file with given name.
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out: Output parameter. Pointer to buffer that will contain the raw pixel data.
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Its size is w * h * (bytes per pixel), bytes per pixel depends on colorType and bitDepth.
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Must be freed after usage with free(*out).
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w: Output parameter. Pointer to width of pixel data.
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h: Output parameter. Pointer to height of pixel data.
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filename: Path on disk of the PNG file.
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colorType: the desired color type for the raw output image. See explanation on PNG color types.
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bitDepth: the desired bit depth for the raw output image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned LodePNG_decode_file(unsigned char** out, unsigned* w, unsigned* h,
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const char* filename, unsigned colorType, unsigned bitDepth);
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/*Same as LodePNG_decode_file, but uses colorType = 6 and bitDepth = 8 by default (32-bit RGBA)*/
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unsigned LodePNG_decode32_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename);
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/*Same as LodePNG_decode_file, but uses colorType = 2 and bitDepth = 8 by default (24-bit RGB)*/
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unsigned LodePNG_decode24_file(unsigned char** out, unsigned* w, unsigned* h, const char* filename);
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#endif /*LODEPNG_COMPILE_DISK*/
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#endif /*LODEPNG_COMPILE_DECODER*/
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#ifdef LODEPNG_COMPILE_ENCODER
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/*
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Converts raw pixel data into a PNG image in memory. The colorType and bitDepth
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of the output PNG image cannot be chosen, they are automatically determined
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by the colorType, bitDepth and content of the input pixel data.
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out: Output parameter. Pointer to buffer that will contain the raw pixel data.
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Must be freed after usage with free(*out).
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outsize: Output parameter. Pointer to the size in bytes of the out buffer.
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image: The raw pixel data to encode. The size of this buffer should be
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w * h * (bytes per pixel), bytes per pixel depends on colorType and bitDepth.
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w: width of the raw pixel data in pixels.
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h: height of the raw pixel data in pixels.
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colorType: the color type of the raw input image. See explanation on PNG color types.
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bitDepth: the bit depth of the raw input image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned LodePNG_encode(unsigned char** out, size_t* outsize,
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const unsigned char* image, unsigned w, unsigned h, unsigned colorType, unsigned bitDepth);
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/*Same as LodePNG_encode, but uses colorType = 6 and bitDepth = 8 by default (32-bit RGBA).*/
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unsigned LodePNG_encode32(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h);
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/*Same as LodePNG_encode, but uses colorType = 2 and bitDepth = 8 by default (24-bit RGB).*/
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unsigned LodePNG_encode24(unsigned char** out, size_t* outsize, const unsigned char* image, unsigned w, unsigned h);
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#ifdef LODEPNG_COMPILE_DISK
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/*
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Converts raw pixel data into a PNG file on disk. Same as LodePNG_encode, but
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outputs to disk instead of memory buffer.
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filename: path to file on disk to write the PNG image to.
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image: The raw pixel data to encode. The size of this buffer should be
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w * h * (bytes per pixel), bytes per pixel depends on colorType and bitDepth.
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w: width of the raw pixel data in pixels.
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h: height of the raw pixel data in pixels.
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colorType: the color type of the raw input image. See explanation on PNG color types.
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bitDepth: the bit depth of the raw input image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned LodePNG_encode_file(const char* filename, const unsigned char* image,
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unsigned w, unsigned h, unsigned colorType, unsigned bitDepth);
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/*Same as LodePNG_encode_file, but uses colorType = 6 and bitDepth = 8 by default (32-bit RGBS).*/
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unsigned LodePNG_encode32_file(const char* filename, const unsigned char* image, unsigned w, unsigned h);
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/*Same as LodePNG_encode_file, but uses colorType = 2 and bitDepth = 8 by default (24-bit RGB).*/
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unsigned LodePNG_encode24_file(const char* filename, const unsigned char* image, unsigned w, unsigned h);
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#endif /*LODEPNG_COMPILE_DISK*/
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#endif /*LODEPNG_COMPILE_ENCODER*/
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#ifdef __cplusplus
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namespace LodePNG
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{
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#ifdef LODEPNG_COMPILE_DECODER
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/*
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Converts PNG data in memory to raw pixel data.
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out: Output parameter, std::vector containing the raw pixel data. Its size
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will be w * h * (bytes per pixel), where bytes per pixel is 4 if the default
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colorType=6 and bitDepth=8 is used. The pixels are 32-bit RGBA bit in that case.
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w: Output parameter, width of the image in pixels.
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h: Output parameter, height of the image in pixels.
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in: Memory buffer with the PNG file.
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insize: size of the in buffer.
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colorType: the desired color type for the raw output image. See explanation on PNG color types.
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bitDepth: the desired bit depth for the raw output image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
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const unsigned char* in, size_t insize, unsigned colorType = LCT_RGBA, unsigned bitDepth = 8);
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/*
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Same as the decode function that takes a unsigned char buffer, but instead of giving
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a pointer and a size, this takes the input buffer as an std::vector.
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*/
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unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
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const std::vector<unsigned char>& in, unsigned colorType = LCT_RGBA, unsigned bitDepth = 8);
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#ifdef LODEPNG_COMPILE_DISK
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/*
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Converts PNG file from disk to raw pixel data in memory.
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out: Output parameter, std::vector containing the raw pixel data. Its size
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will be w * h * (bytes per pixel), where bytes per pixel is 4 if the default
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colorType=6 and bitDepth=8 is used. The pixels are 32-bit RGBA bit in that case.
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w: Output parameter, width of the image in pixels.
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h: Output parameter, height of the image in pixels.
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filename: Path to PNG file on disk.
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colorType: the desired color type for the raw output image. See explanation on PNG color types.
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bitDepth: the desired bit depth for the raw output image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned decode(std::vector<unsigned char>& out, unsigned& w, unsigned& h,
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const std::string& filename, unsigned colorType = LCT_RGBA, unsigned bitDepth = 8);
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#endif //LODEPNG_COMPILE_DISK
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#endif //LODEPNG_COMPILE_DECODER
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#ifdef LODEPNG_COMPILE_ENCODER
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/*
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Converts 32-bit RGBA raw pixel data into a PNG image in memory.
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out: Output parameter, std::vector containing the PNG image data.
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in: Memory buffer with raw pixel data. The size of this buffer should be
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w * h * (bytes per pixel), With the default colorType=6 and bitDepth=8, bytes
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per pixel should be 4 and the data is a 32-bit RGBA pixel buffer.
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w: Width of the image in pixels.
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h: Height of the image in pixels.
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colorType: the color type of the raw input image. See explanation on PNG color types.
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bitDepth: the bit depth of the raw input image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned encode(std::vector<unsigned char>& out, const unsigned char* in,
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unsigned w, unsigned h, unsigned colorType = LCT_RGBA, unsigned bitDepth = 8);
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/*
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Same as the encode function that takes a unsigned char buffer, but instead of giving
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a pointer and a size, this takes the input buffer as an std::vector.
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*/
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unsigned encode(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
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unsigned w, unsigned h, unsigned colorType = LCT_RGBA, unsigned bitDepth = 8);
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#ifdef LODEPNG_COMPILE_DISK
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/*
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Converts 32-bit RGBA raw pixel data into a PNG file on disk.
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filename: Path to the file to write the PNG image to.
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in: Memory buffer with raw pixel data. The size of this buffer should be
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w * h * (bytes per pixel), With the default colorType=6 and bitDepth=8, bytes
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per pixel should be 4 and the data is a 32-bit RGBA pixel buffer.
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w: Width of the image in pixels.
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h: Height of the image in pixels.
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colorType: the color type of the raw input image. See explanation on PNG color types.
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bitDepth: the bit depth of the raw input image. See explanation on PNG color types.
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Return value: LodePNG error code (0 means no error).
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*/
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unsigned encode(const std::string& filename, const unsigned char* in,
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unsigned w, unsigned h, unsigned colorType = LCT_RGBA, unsigned bitDepth = 8);
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/*
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Same as the encode function that takes a unsigned char buffer, but instead of giving
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a pointer and a size, this takes the input buffer as an std::vector.
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*/
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unsigned encode(const std::string& filename, const std::vector<unsigned char>& in,
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unsigned w, unsigned h, unsigned colorType = LCT_RGBA, unsigned bitDepth = 8);
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#endif //LODEPNG_COMPILE_DISK
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#endif //LODEPNG_COMPILE_ENCODER
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} //namespace LodePNG
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#endif /*__cplusplus*/
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#endif /*LODEPNG_COMPILE_PNG*/
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#ifdef LODEPNG_COMPILE_ERROR_TEXT
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/*
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Returns a textual description of the error code, in English. The
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numerical value of the code itself is not included in this description.
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*/
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const char* LodePNG_error_text(unsigned code);
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#endif /*LODEPNG_COMPILE_ERROR_TEXT*/
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/* ////////////////////////////////////////////////////////////////////////// */
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/* Inflate & Deflate Setting Structs */
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/* ////////////////////////////////////////////////////////////////////////// */
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/*
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These structs contain settings for the decompression and compression of the
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PNG files. Typically you won't need these directly.
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*/
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#ifdef LODEPNG_COMPILE_DECODER
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typedef struct LodePNG_DecompressSettings
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{
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unsigned ignoreAdler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/
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} LodePNG_DecompressSettings;
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extern const LodePNG_DecompressSettings LodePNG_defaultDecompressSettings;
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void LodePNG_DecompressSettings_init(LodePNG_DecompressSettings* settings);
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#endif /*LODEPNG_COMPILE_DECODER*/
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#ifdef LODEPNG_COMPILE_ENCODER
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/*
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Compression settings. Tweaking these settings tweaks the balance between
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speed and compression ratio.
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*/
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typedef struct LodePNG_CompressSettings /*deflate = compress*/
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{
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/*LZ77 related settings*/
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unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/
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unsigned useLZ77; /*whether or not to use LZ77. Should be 1 for proper compression.*/
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unsigned windowSize; /*the maximum is 32768, higher gives more compression but is slower. Typical value: 2048.*/
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} LodePNG_CompressSettings;
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extern const LodePNG_CompressSettings LodePNG_defaultCompressSettings;
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void LodePNG_CompressSettings_init(LodePNG_CompressSettings* settings);
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#endif /*LODEPNG_COMPILE_ENCODER*/
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#ifdef LODEPNG_COMPILE_PNG
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/* ////////////////////////////////////////////////////////////////////////// */
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/* PNG and Raw Image Information Structs */
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/* ////////////////////////////////////////////////////////////////////////// */
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/*
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Info about the color type of an image.
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The same LodePNG_InfoColor struct is used for both the PNG and raw image type,
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even though they are two totally different things.
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*/
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typedef struct LodePNG_InfoColor
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{
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/*header (IHDR)*/
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unsigned colorType; /*color type, see PNG standard or documentation further in this header file*/
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unsigned bitDepth; /*bits per sample, see PNG standard or documentation further in this header file*/
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/*
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palette (PLTE and tRNS)
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This is a dynamically allocated unsigned char array with the colors of the palette, including alpha.
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The value palettesize indicates the amount of colors in the palette.
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The allocated size of the buffer is 4 * palettesize bytes, in order RGBARGBARGBA...
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When encoding a PNG, to store your colors in the palette of the LodePNG_InfoRaw, first use
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LodePNG_InfoColor_clearPalette, then for each color use LodePNG_InfoColor_addPalette.
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If you encode an image without alpha with palette, don't forget to put value 255 in each A byte of the palette.
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When decoding, by default you can ignore this palette, since LodePNG already
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fills the palette colors in the pixels of the raw RGBA output.
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*/
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unsigned char* palette; /*palette in RGBARGBA... order*/
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size_t palettesize; /*palette size in number of colors (amount of bytes is 4 * palettesize)*/
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/*
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transparent color key (tRNS)
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This color uses the same bit depth as the bitDepth value in this struct, which can be 1-bit to 16-bit.
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For greyscale PNGs, r, g and b will all 3 be set to the same.
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When decoding, by default you can ignore this information, since LodePNG sets
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pixels with this key to transparent already in the raw RGBA output.
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*/
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unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/
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unsigned key_r; /*red/greyscale component of color key*/
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unsigned key_g; /*green component of color key*/
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unsigned key_b; /*blue component of color key*/
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} LodePNG_InfoColor;
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/*init, cleanup and copy functions to use with this struct*/
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void LodePNG_InfoColor_init(LodePNG_InfoColor* info);
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void LodePNG_InfoColor_cleanup(LodePNG_InfoColor* info);
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/*return value is error code (0 means no error)*/
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unsigned LodePNG_InfoColor_copy(LodePNG_InfoColor* dest, const LodePNG_InfoColor* source);
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void LodePNG_InfoColor_clearPalette(LodePNG_InfoColor* info);
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/*add 1 color to the palette*/
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unsigned LodePNG_InfoColor_addPalette(LodePNG_InfoColor* info, unsigned char r,
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unsigned char g, unsigned char b, unsigned char a);
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/*additional color info*/
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/*get the total amount of bits per pixel, based on colorType and bitDepth in the struct*/
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unsigned LodePNG_InfoColor_getBpp(const LodePNG_InfoColor* info);
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/*get the amount of color channels used, based on colorType in the struct.
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If a palette is used, it counts as 1 channel.*/
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unsigned LodePNG_InfoColor_getChannels(const LodePNG_InfoColor* info);
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/*is it a greyscale type? (only colorType 0 or 4)*/
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unsigned LodePNG_InfoColor_isGreyscaleType(const LodePNG_InfoColor* info);
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/*has it got an alpha channel? (only colorType 2 or 6)*/
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unsigned LodePNG_InfoColor_isAlphaType(const LodePNG_InfoColor* info);
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/*has it got a palette? (only colorType 3)*/
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unsigned LodePNG_InfoColor_isPaletteType(const LodePNG_InfoColor* info);
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/*only returns true if there is a palette and there is a value in the palette with alpha < 255.
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Loops through the palette to check this.*/
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unsigned LodePNG_InfoColor_hasPaletteAlpha(const LodePNG_InfoColor* info);
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/*
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Check if the given color info indicates the possibility of having non-opaque pixels in the PNG image.
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Returns true if the image can have translucent or invisible pixels (it still be opaque if it doesn't use such pixels).
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Returns false if the image can only have opaque pixels.
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In detail, it returns true only if it's a color type with alpha, or has a palette with non-opaque values,
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or if "key_defined" is true.
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*/
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unsigned LodePNG_InfoColor_canHaveAlpha(const LodePNG_InfoColor* info);
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#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
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/*
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The information of a Time chunk in PNG.
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To make the encoder add a time chunk, set time_defined to 1 and fill in
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the correct values in all the time parameters. LodePNG will not fill the current
|
|
time in these values itself, all it does is copy them over into the chunk bytes.
|
|
*/
|
|
typedef struct LodePNG_Time
|
|
{
|
|
unsigned year; /*2 bytes used (0-65535)*/
|
|
unsigned char month; /*1-12*/
|
|
unsigned char day; /*1-31*/
|
|
unsigned char hour; /*0-23*/
|
|
unsigned char minute; /*0-59*/
|
|
unsigned char second; /*0-60 (to allow for leap seconds)*/
|
|
} LodePNG_Time;
|
|
|
|
/*
|
|
Info about text chunks in a PNG file. The arrays can contain multiple keys
|
|
and strings. The amount of keys and strings is the same. The amount of strings
|
|
ends when the pointer to the string is a null pointer.
|
|
|
|
They keyword of text chunks gives a short description what the actual text
|
|
represents. There are a few standard standard keywords recognised
|
|
by many programs: Title, Author, Description, Copyright, Creation Time,
|
|
Software, Disclaimer, Warning, Source, Comment. It's allowed to use other keys.
|
|
|
|
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.
|
|
*/
|
|
typedef struct LodePNG_Text /*non-international text*/
|
|
{
|
|
/*Don't allocate these text buffers yourself. Use the init/cleanup functions
|
|
correctly and use LodePNG_Text_add and LodePNG_Text_clear.*/
|
|
size_t num; /*the amount of texts in these char** buffers (there may be more texts in itext)*/
|
|
char** keys; /*the keyword of a text chunk (e.g. "Comment")*/
|
|
char** strings; /*the actual text*/
|
|
} LodePNG_Text;
|
|
|
|
/*init, cleanup and copy functions to use with this struct*/
|
|
void LodePNG_Text_init(LodePNG_Text* text);
|
|
void LodePNG_Text_cleanup(LodePNG_Text* text);
|
|
/*return value is error code (0 means no error)*/
|
|
unsigned LodePNG_Text_copy(LodePNG_Text* dest, const LodePNG_Text* source);
|
|
|
|
/*Use these functions instead of allocating the char**s manually*/
|
|
void LodePNG_Text_clear(LodePNG_Text* text); /*use this to clear the texts again after you filled them in*/
|
|
unsigned LodePNG_Text_add(LodePNG_Text* text, const char* key, const char* str); /*push back both texts at once*/
|
|
|
|
/*
|
|
Info about international text chunks in a PNG file. The arrays can contain multiple keys
|
|
and strings. The amount of keys, lengtags, transkeys and strings is the same.
|
|
The amount of strings ends when the pointer to the string is a null pointer.
|
|
|
|
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.
|
|
*/
|
|
typedef struct LodePNG_IText /*international text*/
|
|
{
|
|
/*Don't allocate these text buffers yourself. Use the init/cleanup functions
|
|
correctly and use LodePNG_IText_add and LodePNG_IText_clear.*/
|
|
|
|
/*the amount of international texts in this PNG*/
|
|
size_t num;
|
|
/*the English keyword of the text chunk (e.g. "Comment")*/
|
|
char** keys;
|
|
/*the language tag for this text's international language, ISO/IEC 646 string, e.g. ISO 639 language tag*/
|
|
char** langtags;
|
|
/*keyword translated to the international language - UTF-8 string*/
|
|
char** transkeys;
|
|
/*the actual international text - UTF-8 string*/
|
|
char** strings;
|
|
} LodePNG_IText;
|
|
|
|
/*init, cleanup and copy functions to use with this struct*/
|
|
void LodePNG_IText_init(LodePNG_IText* text);
|
|
void LodePNG_IText_cleanup(LodePNG_IText* text);
|
|
/*return value is error code (0 means no error)*/
|
|
unsigned LodePNG_IText_copy(LodePNG_IText* dest, const LodePNG_IText* source);
|
|
|
|
/*Use these functions instead of allocating the char**s manually*/
|
|
void LodePNG_IText_clear(LodePNG_IText* text); /*use this to clear the itexts again after you filled them in*/
|
|
unsigned LodePNG_IText_add(LodePNG_IText* text, 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*/
|
|
|
|
#ifdef LODEPNG_COMPILE_UNKNOWN_CHUNKS
|
|
/*
|
|
Unknown chunks read from the PNG, or extra chunks the user wants to have added
|
|
in the encoded PNG.
|
|
*/
|
|
typedef struct LodePNG_UnknownChunks
|
|
{
|
|
/*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_append_chunk, to read/write this struct.
|
|
*/
|
|
unsigned char* data[3];
|
|
size_t datasize[3]; /*size in bytes of the unknown chunks, given for protection*/
|
|
|
|
} LodePNG_UnknownChunks;
|
|
|
|
/*init, cleanup and copy functions to use with this struct*/
|
|
void LodePNG_UnknownChunks_init(LodePNG_UnknownChunks* chunks);
|
|
void LodePNG_UnknownChunks_cleanup(LodePNG_UnknownChunks* chunks);
|
|
/*return value is error code (0 means no error)*/
|
|
unsigned LodePNG_UnknownChunks_copy(LodePNG_UnknownChunks* dest, const LodePNG_UnknownChunks* src);
|
|
#endif /*LODEPNG_COMPILE_UNKNOWN_CHUNKS*/
|
|
|
|
/*
|
|
Information about the PNG image, except pixels and sometimes except width and height.
|
|
*/
|
|
typedef struct LodePNG_InfoPng
|
|
{
|
|
/*header (IHDR), palette (PLTE) and transparency (tRNS)*/
|
|
|
|
/*
|
|
Note: width and height are only used as information of a decoded PNG image. When encoding one, you don't have
|
|
to specify width and height in an LodePNG_Info struct, but you give them as parameters of the encode function.
|
|
The rest of the LodePNG_Info struct IS used by the encoder though!
|
|
*/
|
|
unsigned width; /*width of the image in pixels (ignored by encoder, but filled in by decoder)*/
|
|
unsigned height; /*height of the image in pixels (ignored by encoder, but filled in by decoder)*/
|
|
unsigned compressionMethod; /*compression method of the original file. Always 0.*/
|
|
unsigned filterMethod; /*filter method of the original file*/
|
|
unsigned interlaceMethod; /*interlace method of the original file*/
|
|
LodePNG_InfoColor color; /*color type and bits, palette and transparency of the PNG file*/
|
|
|
|
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
/*
|
|
suggested background color (bKGD)
|
|
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 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)*/
|
|
LodePNG_Text text;
|
|
|
|
/*international text chunks (iTXt)*/
|
|
LodePNG_IText itext;
|
|
|
|
/*time chunk (tIME)*/
|
|
unsigned char time_defined; /*if 0, no tIME chunk was or will be generated in the PNG image*/
|
|
LodePNG_Time 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 char phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/
|
|
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
|
|
|
|
#ifdef LODEPNG_COMPILE_UNKNOWN_CHUNKS
|
|
/*unknown chunks*/
|
|
LodePNG_UnknownChunks unknown_chunks;
|
|
#endif /*LODEPNG_COMPILE_UNKNOWN_CHUNKS*/
|
|
} LodePNG_InfoPng;
|
|
|
|
/*init, cleanup and copy functions to use with this struct*/
|
|
void LodePNG_InfoPng_init(LodePNG_InfoPng* info);
|
|
void LodePNG_InfoPng_cleanup(LodePNG_InfoPng* info);
|
|
/*return value is error code (0 means no error)*/
|
|
unsigned LodePNG_InfoPng_copy(LodePNG_InfoPng* dest, const LodePNG_InfoPng* source);
|
|
|
|
/*
|
|
Contains user-chosen information about the raw image data, which is independent of the PNG image
|
|
With raw images, I mean the image data in the form of the simple raw buffer to which the
|
|
compressed PNG data is decoded, or from which a PNG image can be encoded.
|
|
*/
|
|
typedef struct LodePNG_InfoRaw
|
|
{
|
|
LodePNG_InfoColor color; /*color info of the raw image, note that the same struct as for PNG data is used.*/
|
|
} LodePNG_InfoRaw;
|
|
|
|
/*init, cleanup and copy functions to use with this struct*/
|
|
void LodePNG_InfoRaw_init(LodePNG_InfoRaw* info);
|
|
void LodePNG_InfoRaw_cleanup(LodePNG_InfoRaw* info);
|
|
/*return value is error code (0 means no error)*/
|
|
unsigned LodePNG_InfoRaw_copy(LodePNG_InfoRaw* dest, const LodePNG_InfoRaw* source);
|
|
|
|
/*
|
|
Converts raw buffer from one color type to another color type, based on
|
|
LodePNG_InfoColor 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_InfoColor_getBpp)
|
|
*/
|
|
unsigned LodePNG_convert(unsigned char* out, const unsigned char* in, LodePNG_InfoColor* infoOut,
|
|
LodePNG_InfoColor* infoIn, unsigned w, unsigned h);
|
|
|
|
#ifdef LODEPNG_COMPILE_DECODER
|
|
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
/* LodePNG 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 LodePNG_DecodeSettings
|
|
{
|
|
LodePNG_DecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/
|
|
|
|
unsigned ignoreCrc; /*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 readTextChunks; /*if false but rememberUnknownChunks is true, they're stored in the unknown chunks*/
|
|
#endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
|
|
|
|
#ifdef LODEPNG_COMPILE_UNKNOWN_CHUNKS
|
|
/*store all bytes from unknown chunks in the InfoPng (off by default, useful for a png editor)*/
|
|
unsigned rememberUnknownChunks;
|
|
#endif /*LODEPNG_COMPILE_UNKNOWN_CHUNKS*/
|
|
} LodePNG_DecodeSettings;
|
|
|
|
void LodePNG_DecodeSettings_init(LodePNG_DecodeSettings* settings);
|
|
|
|
/*
|
|
The LodePNG_Decoder struct has most input and output parameters the decoder uses,
|
|
such as the settings, the info of the PNG and the raw data, and the error. Only
|
|
the pixel buffer is not contained in this struct.
|
|
*/
|
|
typedef struct LodePNG_Decoder
|
|
{
|
|
LodePNG_DecodeSettings settings; /*the decoding settings*/
|
|
LodePNG_InfoRaw infoRaw; /*specifies the format in which you would like to get the raw pixel buffer*/
|
|
LodePNG_InfoPng infoPng; /*info of the PNG image obtained after decoding*/
|
|
unsigned error;
|
|
} LodePNG_Decoder;
|
|
|
|
/*init, cleanup and copy functions to use with this struct*/
|
|
void LodePNG_Decoder_init(LodePNG_Decoder* decoder);
|
|
void LodePNG_Decoder_cleanup(LodePNG_Decoder* decoder);
|
|
void LodePNG_Decoder_copy(LodePNG_Decoder* dest, const LodePNG_Decoder* source);
|
|
|
|
/*
|
|
Decode based on a LodePNG_Decoder.
|
|
This function allocates the out buffer and stores the size in *outsize. This buffer
|
|
needs to be freed after usage.
|
|
Other information about the PNG file, such as the size, colorType and extra chunks
|
|
are stored in the infoPng field of the LodePNG_Decoder.
|
|
*/
|
|
void LodePNG_Decoder_decode(LodePNG_Decoder* decoder, unsigned char** out, size_t* outsize,
|
|
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 infoPng field of the LodePNG_Decoder.
|
|
*/
|
|
void LodePNG_Decoder_inspect(LodePNG_Decoder* decoder, const unsigned char* in, size_t insize);
|
|
#endif /*LODEPNG_COMPILE_DECODER*/
|
|
|
|
#ifdef LODEPNG_COMPILE_ENCODER
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
/* LodePNG Encoder */
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
|
|
/*Settings for the encoder.*/
|
|
typedef struct LodePNG_EncodeSettings
|
|
{
|
|
LodePNG_CompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/
|
|
|
|
/*Brute-force-search PNG filters by compressing each filter for each scanline.
|
|
This gives better compression, at the cost of being super slow.
|
|
Don't enable this for normal image saving, compression can take minutes
|
|
instead of seconds. This is experimental. If enabled, compression still isn't
|
|
as good as some other PNG encoders and optimizers, except for some images.
|
|
If you enable this, also consider setting zlibsettings.windowSize to 32768, and consider
|
|
using a less than 24-bit per pixel colorType if the image has <= 256 colors, for optimal compression.
|
|
Default: 0 (false)*/
|
|
unsigned bruteForceFilters;
|
|
|
|
/*automatically use color type without alpha instead of given one, if given image is opaque*/
|
|
unsigned autoLeaveOutAlphaChannel;
|
|
/*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 version as text chunk*/
|
|
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*/
|
|
} LodePNG_EncodeSettings;
|
|
|
|
void LodePNG_EncodeSettings_init(LodePNG_EncodeSettings* settings);
|
|
|
|
/*
|
|
This struct has most input and output parameters the encoder uses,
|
|
such as the settings, the info of the PNG and the raw data, and the error. Only
|
|
the pixel buffer is not contained in this struct.
|
|
*/
|
|
typedef struct LodePNG_Encoder
|
|
{
|
|
/*compression settings of the encoder*/
|
|
LodePNG_EncodeSettings settings;
|
|
/*the info specified by the user is not changed by the encoder. The encoder
|
|
will try to generate a PNG close to the given info.*/
|
|
LodePNG_InfoPng infoPng;
|
|
/*put the properties of the input raw image in here*/
|
|
LodePNG_InfoRaw infoRaw;
|
|
/*error value filled in if error happened, or 0 if all went ok*/
|
|
unsigned error;
|
|
} LodePNG_Encoder;
|
|
|
|
/*init, cleanup and copy functions to use with this struct*/
|
|
void LodePNG_Encoder_init(LodePNG_Encoder* encoder);
|
|
void LodePNG_Encoder_cleanup(LodePNG_Encoder* encoder);
|
|
void LodePNG_Encoder_copy(LodePNG_Encoder* dest, const LodePNG_Encoder* source);
|
|
|
|
/*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/
|
|
void LodePNG_Encoder_encode(LodePNG_Encoder* encoder, unsigned char** out, size_t* outsize,
|
|
const unsigned char* image, unsigned w, unsigned h);
|
|
#endif /*LODEPNG_COMPILE_ENCODER*/
|
|
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
/* Chunk Traversing Utilities */
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
|
|
/*
|
|
LodePNG_chunk functions:
|
|
These functions need as input a large enough amount of allocated memory.
|
|
These functions can be used on raw PNG data, but they are exposed in the API
|
|
because they are needed if you want to traverse the unknown chunks stored
|
|
in the LodePNG_UnknownChunks struct, or add new ones to it.
|
|
*/
|
|
|
|
/*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);
|
|
|
|
/*
|
|
These functions get properties of PNG chunks gotten from capitalization of chunk
|
|
type name, as defined by the PNG standard.
|
|
*/
|
|
|
|
/*
|
|
properties of PNG chunks gotten from capitalization of chunk type name, as defined by the standard
|
|
0: ancillary chunk, 1: it's one of the critical chunk types
|
|
*/
|
|
unsigned char LodePNG_chunk_critical(const unsigned char* chunk);
|
|
|
|
/*0: public, 1: private*/
|
|
unsigned char LodePNG_chunk_private(const unsigned char* chunk);
|
|
|
|
/*0: the chunk is unsafe to copy, 1: the chunk is safe to copy*/
|
|
unsigned char LodePNG_chunk_safetocopy(const unsigned char* chunk);
|
|
|
|
/*get pointer to the data of the chunk*/
|
|
unsigned char* LodePNG_chunk_data(unsigned char* chunk);
|
|
|
|
/*get pointer to the data of the chunk*/
|
|
const unsigned char* LodePNG_chunk_data_const(const unsigned char* chunk);
|
|
|
|
/*returns 0 if the crc is correct, 1 if it's incorrect*/
|
|
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_append_chunk(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_create_chunk(unsigned char** out, size_t* outlength, unsigned length,
|
|
const char* type, const unsigned char* data);
|
|
#endif /*LODEPNG_COMPILE_PNG*/
|
|
|
|
#ifdef LODEPNG_COMPILE_ZLIB
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
/* Zlib encoder and decoder */
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
|
|
/*
|
|
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
|
|
/*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 LodePNG_DecompressSettings* settings);
|
|
#endif /*LODEPNG_COMPILE_DECODER*/
|
|
|
|
#ifdef LODEPNG_COMPILE_ENCODER
|
|
/*Compresses data with Zlib. Reallocates the out buffer and appends the 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 LodePNG_CompressSettings* 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 are responsible for freeing 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_loadFile(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_saveFile(const unsigned char* buffer, size_t buffersize, const char* filename);
|
|
#endif /*LODEPNG_COMPILE_DISK*/
|
|
|
|
#ifdef __cplusplus
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
/* LodePNG C++ wrapper */
|
|
/* ////////////////////////////////////////////////////////////////////////// */
|
|
|
|
//The LodePNG C++ wrapper uses classes with handy constructors and destructors
|
|
//instead of manual init and cleanup functions, and uses std::vectors instead of
|
|
//manually allocated memory buffers.
|
|
|
|
namespace LodePNG
|
|
{
|
|
#ifdef LODEPNG_COMPILE_ZLIB
|
|
//The C++ wrapper for the zlib part
|
|
#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 LodePNG_DecompressSettings& settings = LodePNG_defaultDecompressSettings);
|
|
|
|
//Zlib-decompress an std::vector
|
|
unsigned decompress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
|
|
const LodePNG_DecompressSettings& settings = LodePNG_defaultDecompressSettings);
|
|
#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 LodePNG_CompressSettings& settings = LodePNG_defaultCompressSettings);
|
|
|
|
//Zlib-compress an std::vector
|
|
unsigned compress(std::vector<unsigned char>& out, const std::vector<unsigned char>& in,
|
|
const LodePNG_CompressSettings& settings = LodePNG_defaultCompressSettings);
|
|
#endif //LODEPNG_COMPILE_ENCODER
|
|
#endif //LODEPNG_COMPILE_ZLIB
|
|
|
|
#ifdef LODEPNG_COMPILE_PNG
|
|
#ifdef LODEPNG_COMPILE_DECODER
|
|
/*
|
|
Class to decode a PNG image. Before decoding, settings can be set and
|
|
after decoding, extra information about the PNG can be retrieved.
|
|
Extends from the C-struct LodePNG_Decoder to add constructors and destructors
|
|
to initialize/cleanup it automatically. Beware, no virtual destructor is used.
|
|
*/
|
|
class Decoder : public LodePNG_Decoder
|
|
{
|
|
public:
|
|
|
|
Decoder();
|
|
~Decoder();
|
|
void operator=(const LodePNG_Decoder& other);
|
|
|
|
//decode PNG buffer to raw out buffer. Width and height can be retrieved with getWidth() and
|
|
//getHeight() and error should be checked with hasError() and getError()
|
|
void decode(std::vector<unsigned char>& out, const unsigned char* in, size_t insize);
|
|
|
|
//decode PNG buffer to raw out buffer. Width and height can be retrieved with getWidth() and
|
|
//getHeight() and error should be checked with hasError() and getError()
|
|
void decode(std::vector<unsigned char>& out, const std::vector<unsigned char>& in);
|
|
|
|
//inspect functions: get only the info from the PNG header. The info can then be retrieved with
|
|
//the functions of this class.
|
|
void inspect(const unsigned char* in, size_t insize);
|
|
|
|
//inspect functions: get only the info from the PNG header. The info can then be retrieved with
|
|
//the functions of this class.
|
|
void inspect(const std::vector<unsigned char>& in);
|
|
|
|
//error checking after decoding
|
|
bool hasError() const;
|
|
unsigned getError() const;
|
|
|
|
//convenient access to some InfoPng parameters after decoding
|
|
unsigned getWidth() const; //width of image in pixels
|
|
unsigned getHeight() const; //height of image in pixels
|
|
unsigned getBpp(); //bits per pixel
|
|
unsigned getChannels(); //amount of channels
|
|
unsigned isGreyscaleType(); //is it a greyscale type? (colorType 0 or 4)
|
|
unsigned isAlphaType(); //has it an alpha channel? (colorType 2 or 6)
|
|
|
|
//getters and setters for the decoding settings
|
|
const LodePNG_DecodeSettings& getSettings() const;
|
|
LodePNG_DecodeSettings& getSettings();
|
|
void setSettings(const LodePNG_DecodeSettings& info);
|
|
|
|
//getters and setters for the PNG image info, after decoding this describes information of the PNG image
|
|
const LodePNG_InfoPng& getInfoPng() const;
|
|
LodePNG_InfoPng& getInfoPng();
|
|
void setInfoPng(const LodePNG_InfoPng& info);
|
|
void swapInfoPng(LodePNG_InfoPng& info); //faster than copying with setInfoPng
|
|
|
|
//getters and setters for the raw image info, this determines in what format
|
|
//you get the pixel buffer from the decoder
|
|
const LodePNG_InfoRaw& getInfoRaw() const;
|
|
LodePNG_InfoRaw& getInfoRaw();
|
|
void setInfoRaw(const LodePNG_InfoRaw& info);
|
|
};
|
|
#endif //LODEPNG_COMPILE_DECODER
|
|
|
|
#ifdef LODEPNG_COMPILE_ENCODER
|
|
/*
|
|
Class to encode a PNG image. Before encoding, settings can be set.
|
|
Extends from the C-struct LodePNG_Enoder to add constructors and destructors
|
|
to initialize/cleanup it automatically. Beware, no virtual destructor is used.
|
|
*/
|
|
class Encoder : public LodePNG_Encoder
|
|
{
|
|
public:
|
|
|
|
Encoder();
|
|
~Encoder();
|
|
void operator=(const LodePNG_Encoder& other);
|
|
|
|
//encoding image to PNG buffer
|
|
void encode(std::vector<unsigned char>& out, const unsigned char* image, unsigned w, unsigned h);
|
|
|
|
//encoding image to PNG buffer
|
|
void encode(std::vector<unsigned char>& out, const std::vector<unsigned char>& image, unsigned w, unsigned h);
|
|
|
|
//error checking after decoding
|
|
bool hasError() const;
|
|
unsigned getError() const;
|
|
|
|
//convenient direct access to some parameters of the InfoPng
|
|
void clearPalette();
|
|
void addPalette(unsigned char r, unsigned char g, unsigned char b, unsigned char a); //add 1 color to the palette
|
|
#ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
void clearText();
|
|
void addText(const std::string& key, const std::string& str); //push back both texts at once
|
|
void clearIText();
|
|
void addIText(const std::string& key, const std::string& langtag,
|
|
const std::string& transkey, const std::string& str);
|
|
#endif //LODEPNG_COMPILE_ANCILLARY_CHUNKS
|
|
|
|
//getters and setters for the encoding settings
|
|
const LodePNG_EncodeSettings& getSettings() const;
|
|
LodePNG_EncodeSettings& getSettings();
|
|
void setSettings(const LodePNG_EncodeSettings& info);
|
|
|
|
//getters and setters for the PNG image info, this describes what color type
|
|
//and other settings the resulting PNG should have
|
|
const LodePNG_InfoPng& getInfoPng() const;
|
|
LodePNG_InfoPng& getInfoPng();
|
|
void setInfoPng(const LodePNG_InfoPng& info);
|
|
void swapInfoPng(LodePNG_InfoPng& info); //faster than copying with setInfoPng
|
|
|
|
//getters and setters for the raw image info, this describes how the encoder
|
|
//should interpret the input pixel buffer
|
|
const LodePNG_InfoRaw& getInfoRaw() const;
|
|
LodePNG_InfoRaw& getInfoRaw();
|
|
void setInfoRaw(const LodePNG_InfoRaw& info);
|
|
};
|
|
#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 loadFile(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 saveFile(const std::vector<unsigned char>& buffer, const std::string& filename);
|
|
#endif //LODEPNG_COMPILE_DISK
|
|
#endif //LODEPNG_COMPILE_PNG
|
|
} //namespace LodePNG
|
|
#endif /*end of __cplusplus wrapper*/
|
|
|
|
/*
|
|
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
|
|
[ ] LZ77 encoder more like the one described in zlib - to make sure it's patentfree
|
|
[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)
|
|
[ ] 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
|
|
---------------------
|
|
|
|
This documentations contains background information and examples. For the function
|
|
and class documentation, see the comments in the declarations above.
|
|
|
|
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. Default Behaviour of LodePNG
|
|
6.3. Color Conversions
|
|
6.4. More Notes
|
|
7. error values
|
|
8. chunks and PNG editing
|
|
9. compiler support
|
|
10. examples
|
|
10.1. decoder C++ example
|
|
10.2. encoder C++ example
|
|
10.3. 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. It can be implemented in a patent-free way.
|
|
|
|
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://members.gamedev.net/lode/projects/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
|
|
files lodepng_examples.c or lodepng_examples.cpp 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. To decode PNGs, there's a Decoder struct or class that
|
|
can convert any PNG file data into an RGBA image buffer with a single function
|
|
call. To encode PNGs, there's an Encoder struct or class that can convert image
|
|
data into PNG file data with a single function call. 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, demoscene
|
|
productions, saving a screenshot, images in programs that require them for simple
|
|
usage, ... 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, ...
|
|
LodePNG has a standards conformant decoder and encoder, and supports the ability
|
|
to make a somewhat conformant editor.
|
|
|
|
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
|
|
|
|
|
|
2. C and C++ version
|
|
--------------------
|
|
|
|
The C version uses buffers allocated with alloc that you need to free()
|
|
yourself. On top of that, 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 constructors and destructors that take care of these things,
|
|
and uses std::vectors in the interface for storing data.
|
|
|
|
Both the C and the C++ version are contained in this file! The C++ code depends on
|
|
the C code, the C code works on its own.
|
|
|
|
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
|
|
-----------
|
|
|
|
As with most software, even if carefully designed, it's always possible that
|
|
LodePNG may contain possible exploits.
|
|
|
|
If you discover a possible exploit, 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, to avoid exploits
|
|
-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 LodePNG_Decoder and its
|
|
functions. For C++, simple decoding can be done with the LodePNG::decode functions
|
|
and advanced decoding with the LodePNG::Decoder class.
|
|
|
|
The Decoder contains 3 components:
|
|
*) LodePNG_InfoPng: it stores information about the PNG (the input) in an LodePNG_InfoPng struct,
|
|
don't modify this one yourself
|
|
*) Settings: you can specify a few other settings for the decoder to use
|
|
*) LodePNG_InfoRaw: here you can say what type of raw image (the output) you want to get
|
|
|
|
Some of the parameters described below may be inside the sub-struct "LodePNG_InfoColor color".
|
|
In the C and C++ version, when using Info structs outside of the decoder or encoder, you need to use their
|
|
init and cleanup functions, but normally you use the ones in the decoder that are already handled
|
|
in the init and cleanup functions of the decoder itself.
|
|
|
|
=LodePNG_InfoPng=
|
|
|
|
This contains information such as the original color type of the PNG image, text
|
|
comments, suggested background color, etc... More details about the LodePNG_InfoPng struct
|
|
are at its declaration documentation.
|
|
|
|
Because the dimensions of the image are important, there are shortcuts to get them in the
|
|
C++ version: use decoder.getWidth() and decoder.getHeight().
|
|
In the C version, use decoder.infoPng.width and decoder.infoPng.height.
|
|
|
|
=LodePNG_InfoRaw=
|
|
|
|
In the LodePNG_InfoRaw struct of the Decoder, 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 to your LodePNG_InfoRaw
|
|
settings. Not all combinations of color conversions are supported though, see
|
|
a different section for information about the color modes and supported conversions.
|
|
|
|
Palette of LodePNG_InfoRaw isn't used by the Decoder, when converting from palette color
|
|
to palette color, the values of the pixels are left untouched so that the colors
|
|
will change if the palette is different. Color key of LodePNG_InfoRaw is not used by the
|
|
Decoder. If setting color_convert is false then LodePNG_InfoRaw is completely ignored,
|
|
but it will be modified to match the color type of the PNG so will be overwritten.
|
|
|
|
By default, 32-bit color is used for the result.
|
|
|
|
=Settings=
|
|
|
|
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 LodePNG_InfoPng.
|
|
|
|
|
|
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 LodePNG_Encoder and its
|
|
functions. For C++, simple encoding can be done with the LodePNG::encode functions
|
|
and advanced decoding with the LodePNG::Encoder class.
|
|
|
|
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.
|
|
|
|
Like the Decoder, the Encoder has 3 components:
|
|
*) LodePNG_InfoRaw: here you say what color type of the raw image (the input) has
|
|
*) Settings: you can specify a few settings for the encoder to use
|
|
*) LodePNG_InfoPng: the same LodePNG_InfoPng struct as created by the Decoder. For the encoder,
|
|
with this you specify how you want the PNG (the output) to be.
|
|
|
|
Some of the parameters described below may be inside the sub-struct "LodePNG_InfoColor color".
|
|
In the C and C++ version, when using Info structs outside of the decoder or encoder, you need to use their
|
|
init and cleanup functions, but normally you use the ones in the encoder that are already handled
|
|
in the init and cleanup functions of the decoder itself.
|
|
|
|
=LodePNG_InfoPng=
|
|
|
|
The Decoder class stores information about the PNG image in an LodePNG_InfoPng object. With
|
|
the Encoder you can do the opposite: you give it an LodePNG_InfoPng object, and it'll try
|
|
to match the LodePNG_InfoPng you give as close as possible in the PNG it encodes. For
|
|
example in the LodePNG_InfoPng you can specify the color type you want to use, possible
|
|
tEXt chunks you want the PNG to contain, etc... For an explanation of all the
|
|
values in LodePNG_InfoPng see a further section. Not all PNG color types are supported
|
|
by the Encoder.
|
|
|
|
The encoder will not always exactly match the LodePNG_InfoPng struct you give,
|
|
it tries as close as possible. Some things are ignored by the encoder. The width
|
|
and height of LodePNG_InfoPng are ignored as well, because instead the width and
|
|
height of the raw image you give in the input are used. In fact the encoder
|
|
currently uses only the following settings from it:
|
|
-colorType and bitDepth: the ones it supports
|
|
-text chunks, that you can add to the LodePNG_InfoPng with "addText"
|
|
-the color key, if applicable for the given color type
|
|
-the palette, if you encode to a PNG with colorType 3
|
|
-the background color: it'll add a bKGD chunk to the PNG if one is given
|
|
-the interlaceMethod: None (0) or Adam7 (1)
|
|
|
|
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.
|
|
|
|
=LodePNG_InfoRaw=
|
|
|
|
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.
|
|
|
|
=Settings=
|
|
|
|
The following settings are supported (some are in sub-structs):
|
|
*) autoLeaveOutAlphaChannel: when this option is enabled, when you specify a PNG
|
|
color type with alpha channel (not to be confused with the color type of the raw
|
|
image you specify!!), but the encoder detects that all pixels of the given image
|
|
are opaque, then it'll automatically use the corresponding type without alpha
|
|
channel, resulting in a smaller PNG image.
|
|
*) btype: the block type for LZ77.
|
|
0 = uncompressed, 1 = fixed huffman tree, 2 = dynamic huffman tree (best compression)
|
|
*) useLZ77: whether or not to use LZ77 for compressed block types
|
|
*) windowSize: the window size used by the LZ77 encoder (1 - 32768)
|
|
*) 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 0. 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
|
|
--------------------
|
|
|
|
In LodePNG, the color mode (bits, channels and palette) used in the PNG image,
|
|
and the color mode used in the raw data, are separate and independently
|
|
configurable. Therefore, LodePNG needs to do conversions from one color mode to
|
|
another. Not all possible conversions are supported (e.g. converting to a palette
|
|
or a lower bit depth isn't supported). This section will explain which conversions
|
|
are supported and how to configure this. This explains for example when LodePNG
|
|
uses the settings in LodePNG_InfoPng, LodePNG_InfoRaw and Settings.
|
|
|
|
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 mentions 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 = amount of channels * bitDepth.
|
|
|
|
6.2. Default Behaviour of LodePNG
|
|
---------------------------------
|
|
|
|
By default, the Decoder will convert the data from the PNG to 32-bit RGBA color,
|
|
no matter what color type the PNG has, so that the result can be used directly
|
|
as a texture in OpenGL etc... without worries about what color type the original
|
|
image has.
|
|
|
|
The Encoder assumes by default that the raw input you give it is a 32-bit RGBA
|
|
buffer and will store the PNG as either 32 bit or 24 bit depending on whether
|
|
or not any translucent pixels were detected in it.
|
|
|
|
To get the default behaviour, don't change the values of LodePNG_InfoRaw and
|
|
LodePNG_InfoPng of the encoder, and don't change the values of LodePNG_InfoRaw
|
|
of the decoder.
|
|
|
|
6.3. Color Conversions
|
|
----------------------
|
|
|
|
As explained in the sections about the Encoder and Decoder, you can specify
|
|
color types and bit depths in LodePNG_InfoPng and LodePNG_InfoRaw, to change the default behaviour
|
|
explained above. (for the Decoder you can only specify the LodePNG_InfoRaw, because the
|
|
LodePNG_InfoPng contains what the PNG file has).
|
|
|
|
To avoid some confusion:
|
|
-the Decoder converts from PNG to raw image
|
|
-the Encoder converts from raw image to PNG
|
|
-the color type and bit depth in LodePNG_InfoRaw, are those of the raw image
|
|
-the color type and bit depth in LodePNG_InfoPng, are those of the PNG
|
|
-if the color type of the LodePNG_InfoRaw 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
|
|
and this is supported for any color type.
|
|
|
|
Supported color conversions:
|
|
-It's possible to load PNGs from any colortype and to save PNGs of any colorType.
|
|
-Both encoder and decoder use the same converter. So both encoder and decoder
|
|
suport the same color types at the input and the output. So the decoder supports
|
|
any type of PNG image and can convert it to certain types of raw image, while the
|
|
encoder supports any type of raw data but only certain color types for the output PNG.
|
|
-The converter can convert from _any_ input color type, to 24-bit RGB or 32-bit RGBA (8 bits per channel)
|
|
-The converter can convert from _any_ input color type, to 48-bit RGB or 64-bit RGBA (16 bits per channel)
|
|
-The converter can convert from greyscale input color type, to 8-bit greyscale or greyscale with alpha
|
|
-The converter can convert from greyscale input color type, to 16-bit greyscale or greyscale with alpha
|
|
-If both color types are the same, conversion from anything to anything is possible
|
|
-Color types that are invalid according to the PNG specification are not allowed
|
|
-When converting from a type with alpha channel to one without, the alpha channel information is discarded
|
|
-When converting from a type without alpha channel to one with, the result will be opaque except
|
|
pixels that have the same color as the color key of the input if one was given
|
|
-When converting from 16-bit bitDepth to 8-bit bitDepth, the 16-bit precision information is lost,
|
|
only the most significant byte is kept
|
|
-When converting from 8-bit bitDepth to 16-bit bitDepth, the 8-bit byte is duplicated, so that 0 stays 0, and
|
|
the 8-bit maximum 255 is converted to the 16-bit maximum 65535. Something similar happens at bit level for
|
|
converting very low bit depths to 8 or 16 bit.
|
|
-Converting from color to greyscale or to palette is not supported on purpose: there are multiple possible
|
|
algorithms to do this color reduction, LodePNG does not want to pick one and leaves this choice to the
|
|
user instead, because it's beyond the scope of PNG encoding.
|
|
-Converting from a palette to a palette, only keeps the indices, it ignores the colors defined in the
|
|
palette without giving an error
|
|
|
|
No conversion needed...:
|
|
-If the color type of the PNG image and raw image are the same, then no
|
|
conversion is done, and all color types are supported.
|
|
-In the encoder, you can make it save a PNG with any color by giving the
|
|
LodePNG_InfoRaw and LodePNG_InfoPng the same color type.
|
|
-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
|
|
infoRaw are then ignored.
|
|
|
|
The function LodePNG_convert does this, which is available in the interface but
|
|
normally isn't needed since the encoder and decoder already call it.
|
|
|
|
6.4. More Notes
|
|
---------------
|
|
|
|
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 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.
|
|
|
|
7. error values
|
|
---------------
|
|
|
|
All functions in LodePNG that return an error code, return 0 if everything went
|
|
OK, or one of the code defined by LodePNG 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 error 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 you
|
|
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_append_chunk(unsigned char** out, size_t* outlength, const unsigned char* chunk):
|
|
unsigned LodePNG_create_chunk(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 infoPng
|
|
----------------------
|
|
|
|
The LodePNG_InfoPng struct contains a struct LodePNG_UnknownChunks in it. This
|
|
struct 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.
|
|
|
|
infoPng.unknown_chunks.data[0] is the chunks before PLTE
|
|
infoPng.unknown_chunks.data[1] is the chunks after PLTE, before IDAT
|
|
infoPng.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.rememberUnknownChunks to 1. By default, this option
|
|
is off and is 0.
|
|
|
|
The encoder will always encode unknown chunks that are stored in the infoPng. If
|
|
you need it to add a particular chunk that isn't known by LodePNG, you can use
|
|
LodePNG_append_chunk or LodePNG_create_chunk to the chunk data in
|
|
infoPng.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 and LodePNG will generate the chunk.
|
|
|
|
|
|
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.
|
|
|
|
Use optimization! For both the encoder and decoder, compiling with the best
|
|
optimizations 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 resulting in bad things.
|
|
|
|
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 4.5.1 on Linux.
|
|
|
|
*) Mingw and Bloodshed DevC++
|
|
|
|
The Mingw compiler (a port of gcc) used by Bloodshed DevC++ for Windows is fully
|
|
supported by LodePNG.
|
|
|
|
*) Visual Studio 2005 and Visual C++ 2005 Express Edition
|
|
|
|
Versions 20070604 up to 20080107 have been tested on VS2005 and work. Visual
|
|
studio may give warnings about 'fopen' being deprecated. A multiplatform library
|
|
can't support the proposed Visual Studio alternative however.
|
|
|
|
If you're using LodePNG in VS2005 and don't want to see the deprecated warnings,
|
|
put this on top of lodepng.h before the inclusions: #define _CRT_SECURE_NO_DEPRECATE
|
|
|
|
*) Visual Studio 6.0
|
|
|
|
The C++ version of LodePNG was not supported by Visual Studio 6.0 because Visual
|
|
Studio 6.0 doesn't follow the C++ standard and implements it incorrectly.
|
|
The current C version of LodePNG has not been tested in VS6 but may work now.
|
|
|
|
*) 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, I'm happy to help out make LodePNG
|
|
support the compiler if it supports the ISO C90 and C++ standard well enough and
|
|
the required modification doesn't require using non standard or less good C/C++
|
|
code or headers.
|
|
|
|
|
|
10. examples
|
|
------------
|
|
|
|
This decoder and encoder example show the most basic usage of LodePNG (using the
|
|
classes, not the simple functions, which would be trivial)
|
|
|
|
More complex examples can be found in:
|
|
-lodepng_examples.c: 9 different examples in C, such as showing the image with SDL, ...
|
|
-lodepng_examples.cpp: the same examples in C++ using the C++ wrapper of LodePNG
|
|
|
|
These files can be found on the LodePNG website or searched for on the internet.
|
|
|
|
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> buffer, image; //buffer will contain the PNG file, image will contain the raw pixels
|
|
LodePNG::loadFile(buffer, filename); //load the image file with given filename
|
|
LodePNG::Decoder decoder;
|
|
decoder.decode(image, buffer.size() ? &buffer[0] : 0, (unsigned)buffer.size()); //decode the png
|
|
|
|
//if there's an error, display it
|
|
if(decoder.hasError())
|
|
std::cout << "error " << decoder.getError() << ": "<< LodePNG_error_text(decoder.getError()) << std::endl;
|
|
|
|
int width = decoder.getWidth(); //get the width in pixels
|
|
int height = decoder.getHeight(); //get the height in pixels
|
|
//the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ...
|
|
}
|
|
|
|
//alternative version using the "simple" function
|
|
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 != 0) std::cout << "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. encoder C++ example
|
|
-------------------------
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
#include "lodepng.h"
|
|
#include <iostream>
|
|
|
|
//saves image to filename given as argument. Warning, this overwrites the file without warning!
|
|
int main(int argc, char *argv[])
|
|
{
|
|
//check if user gave a filename
|
|
if(argc <= 1)
|
|
{
|
|
std::cout << "please provide a filename to save to\n";
|
|
return 0;
|
|
}
|
|
|
|
//generate some image
|
|
std::vector<unsigned char> image;
|
|
image.resize(512 * 512 * 4);
|
|
for(unsigned y = 0; y < 512; y++)
|
|
for(unsigned x = 0; x < 512; x++)
|
|
{
|
|
image[4 * 512 * y + 4 * x + 0] = 255 * !(x & y);
|
|
image[4 * 512 * y + 4 * x + 1] = x ^ y;
|
|
image[4 * 512 * y + 4 * x + 2] = x | y;
|
|
image[4 * 512 * y + 4 * x + 3] = 255;
|
|
}
|
|
|
|
//encode and save, using the Encoder class
|
|
std::vector<unsigned char> buffer;
|
|
LodePNG::Encoder encoder;
|
|
encoder.encode(buffer, image, 512, 512);
|
|
LodePNG::saveFile(buffer, argv[1]);
|
|
|
|
//the same as the 4 lines of code above, but in 1 call without the class:
|
|
//LodePNG::encode(argv[1], image, 512, 512);
|
|
}
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
10.3. Decoder C example
|
|
-----------------------
|
|
|
|
This example loads the PNG from a file into a pixel buffer in 1 function call
|
|
|
|
#include "lodepng.h"
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
unsigned error;
|
|
unsigned char* image;
|
|
size_t width, height;
|
|
|
|
if(argc <= 1) return 0;
|
|
|
|
error = LodePNG_decode32_file(&image, &width, &height, filename);
|
|
|
|
if(error != 0) printf("error %u: %s\n", error, LodePNG_error_text(error));
|
|
|
|
//use image here
|
|
|
|
free(image);
|
|
}
|
|
|
|
|
|
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.
|
|
|
|
*) 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) 2005-2011 Lode Vandevenne
|
|
*/
|
|
|
|
#endif
|
|
|