src/PNGImage.cpp

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#include <cassert>
#include <string>
#include <fstream>

#include "PNGImage.h"
#include "RGBAColor.h"
#include "pngHelper.h"


PNGImage::PNGImage(int resX, int resY)
    : Image(resX, resY)
{
}


PNGImage::~PNGImage()
{
}


bool PNGImage::read(const std::string & fileName)
{
    std::ifstream ifile(fileName.c_str());
    if(!ifile.good() )
    {
        throw PNGFileOpenException(fileName);
    }


    // store here image data
    int channels;
    int bit_depth;
    int color_type          = PNG_COLOR_TYPE_RGB;
    unsigned char* buffer   = NULL;

    // read png file
    read_png(fileName.c_str(), buffer, mResX, mResY, channels, bit_depth, color_type, true);

    // check supported color types
    if (!(color_type == PNG_COLOR_TYPE_GRAY
        || color_type == PNG_COLOR_TYPE_RGB
        || color_type == PNG_COLOR_TYPE_RGBA))
    {
        std::cerr << "Image::ReadPNG(" << fileName << "): not supported color type!" << std::endl;
        delete [] buffer;
        return false;
    }

    // currently only support 8 bit
    if (bit_depth != 8)
    {
        std::cerr << "Image::ReadPNG(" << fileName << "): not supported bit depth!" << std::endl;
        delete [] buffer;
        return false;
    }

    LOG("Read PNG File : " << fileName);

    // check whenever we have gray scale png file
    bool grey = color_type == PNG_COLOR_TYPE_GRAY;
    bool rgba = color_type == PNG_COLOR_TYPE_RGBA;

    // create pixel buffer to store the data
    delete [] mPixels;
    mPixels = new RGBAColor[mResX * mResY];

    // copy and convert pixel data
    for (int y=0; y < mResY; y++)
    {
        for (int x=0; x < mResX; x++)
        {
            // convert values
            RGBAColor v = RGBAColor(float(buffer[(y * mResX + x) * channels + (grey ? 0 : 0)]) / 255.0,
                            float(buffer[(y * mResX + x) * channels + (grey ? 0 : 1)]) / 255.0,
                            float(buffer[(y * mResX + x) * channels + (grey ? 0 : 2)]) / 255.0,
                            rgba ? float(buffer[(y * mResX + x) * channels + (grey ? 0 : 3)]) / 255.0 : 1);
            // set pixel
            setPixel(v, x, y);
        }
    }

    // free up the used data
    delete [] buffer;
    return true;
}


void PNGImage::write(const std::string & fileName) const
{
    // store here image data
    int channels    = 3;
    int bit_depth   = 8;
    int color_type  = PNG_COLOR_TYPE_RGB;

    // create pixel to store the data
    unsigned char * buffer = new unsigned char[mResX * mResY * channels];

    // copy and convert pixel data
    for (int y=0; y < mResY; y++)
    {
        for (int x=0; x < mResX; x++)
        {
            // get pixel
            const RGBAColor & p = pixel(x, y);

            // convert values
            buffer[(y * mResX + x) * channels + 0] = static_cast<unsigned char>(255.0 * p.r());
            buffer[(y * mResX + x) * channels + 1] = static_cast<unsigned char>(255.0 * p.g());
            buffer[(y * mResX + x) * channels + 2] = static_cast<unsigned char>(255.0 * p.b());
        }
    }

    // write file
    write_png(fileName.c_str(), buffer, mResX, mResY, channels, bit_depth, color_type, true);

    // free up the used data
    delete [] buffer;
}

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