LodePNG 介绍
LodePNG 是一个 C/C++ 语言用来编码和解码 PNG 图像的库。
示例代码：
/*
LodePNG Examples
Copyright (c) 2005-2012 Lode Vandevenne
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source
distribution.
*/
#include "lodepng.h"
#include /*
3 ways to decode a PNG from a file to RGBA pixel data (and 2 in-memory ways).
*/
//g++ lodepng.cpp example_decode.cpp -ansi -pedantic -Wall -Wextra -O3
//Example 1
//Decode from disk to raw pixels with a single function call
void decodeOneStep(const char* filename)
{
std::vector image; //the raw pixels
unsigned width, height;
//decode
unsigned error = lodepng::decode(image, width, height, filename);
//if there's an error, display it
if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl;
//the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ...
}
//Example 2
//Load PNG file from disk to memory first, then decode to raw pixels in memory.
void decodeTwoSteps(const char* filename)
{
std::vector png;
std::vector image; //the raw pixels
unsigned width, height;
//load and decode
lodepng::load_file(png, filename);
unsigned error = lodepng::decode(image, width, height, png);
//if there's an error, display it
if(error) std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl;
//the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ...
}
//Example 3
//Load PNG file from disk using a State, normally needed for more advanced usage.
void decodeWithState(const char* filename)
{
std::vector png;
std::vector image; //the raw pixels
unsigned width, height;
lodepng::State state; //optionally customize this one
lodepng::load_file(png, filename); //load the image file with given filename
unsigned error = lodepng::decode(image, width, height, state, png);
//if there's an error, display it
if(error) std::cout << "decoder error " << error << ": "<< lodepng_error_text(error) << std::endl;
//the pixels are now in the vector "image", 4 bytes per pixel, ordered RGBARGBA..., use it as texture, draw it, ...
//State state contains extra information about the PNG such as text chunks, ...
}
int main(int argc, char *argv[])
{
const char* filename = argc > 1 ? argv[1] : "test.png";
decodeOneStep(filename);
}