example_encode.cpp

/*
 * 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 "libs/lodepng.h"
#include <iostream>


struct pixel {
    pixel(unsigned char red, unsigned char green, unsigned char blue, unsigned char alpha):_red(red), _green(green), _blue(blue), _alpha(alpha){};
    unsigned char _red, _green, _blue, _alpha;
};

/*
 * 3 ways to encode a PNG from RGBA pixel data to a file (and 2 in-memory ways).
 * NOTE: this samples overwrite the file or test.png without warning!
 */

//g++ lodepng.cpp example_encode.cpp -ansi -pedantic -Wall -Wextra -O3

//Example 1
//Encode from raw pixels to disk with a single function call
//The image argument has width * height RGBA pixels or width * height * 4 bytes
void encodeOneStep(const char* filename, std::vector<unsigned char>& image, unsigned width, unsigned height)
{
    //Encode the image
    unsigned error = lodepng::encode(filename, image, width, height);

    //if there's an error, display it
    if(error) std::cout << "encoder error " << error << ": "<< lodepng_error_text(error) << std::endl;
}

//Example 2
//Encode from raw pixels to an in-memory PNG file first, then write it to disk
//The image argument has width * height RGBA pixels or width * height * 4 bytes
void encodeTwoSteps(const char* filename, std::vector<unsigned char>& image, unsigned width, unsigned height)
{
    std::vector<unsigned char> png;

    unsigned error = lodepng::encode(png, image, width, height);
    if(!error) lodepng::save_file(png, filename);

    //if there's an error, display it
    if(error) std::cout << "encoder error " << error << ": "<< lodepng_error_text(error) << std::endl;
}

//Example 3
//Save a PNG file to disk using a State, normally needed for more advanced usage.
//The image argument has width * height RGBA pixels or width * height * 4 bytes
void encodeWithState(const char* filename, std::vector<unsigned char>& image, unsigned width, unsigned height)
{
    std::vector<unsigned char> png;
    lodepng::State state; //optionally customize this one

    unsigned error = lodepng::encode(png, image, width, height, state);
    if(!error) lodepng::save_file(png, filename);

    //if there's an error, display it
    if(error) std::cout << "encoder error " << error << ": "<< lodepng_error_text(error) << std::endl;
}

//saves image to filename given as argument. Warning, this overwrites the file without warning!
int main(int argc, char *argv[])
{
    //NOTE: this sample will overwrite the file or test.png without warning!
    const char* filename = argc > 1 ? argv[1] : "test.png";

    //generate some image
    unsigned width = 512, height = 512;

    std::vector<pixel> image;

    for(unsigned y = 0; y < height; y++){
        for(unsigned x = 0; x < width; x++){
            image.push_back(pixel(255 * !(x & y), x ^ y, x | y, 255));
        }
    }

    lodepng::encode(filename, reinterpret_cast<unsigned char*>(image.data()), width, height);
}