rgba_image.h

/*
RGBAImage.h
Copyright (C) 2006-2011 Yangli Hector Yee
Copyright (C) 2011-2016 Steven Myint, Jeff Terrace

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
*/

#ifndef PERCEPTUALDIFF_RGBA_IMAGE_H
#define PERCEPTUALDIFF_RGBA_IMAGE_H

#include "exceptions.h"

#include <memory>
#include <stdexcept>
#include <string>
#include <vector>


namespace pdiff
{
    /** Class encapsulating an image containing R, G, B, and A channels.
     *
     * Internal representation assumes data is in the ABGR format, with the RGB
     * color channels premultiplied by the alpha value. Premultiplied alpha is
     * often also called "associated alpha" - see the tiff 6 specification for
     * some discussion -
     * http://partners.adobe.com/asn/developer/PDFS/TN/TIFF6.pdf
     *
     */
    class RGBAImage
    {
    public:

        RGBAImage(const unsigned int w, const unsigned int h, const std::string &name="")
            : width_(w), height_(h), name_(name), data_(w * h)
        {
        }

        unsigned char get_red(const unsigned int i) const
        {
            return (data_[i] & 0xff);
        }

        unsigned char get_green(const unsigned int i) const
        {
            return ((data_[i] >> 8) & 0xff);
        }

        unsigned char get_blue(const unsigned int i) const
        {
            return ((data_[i] >> 16) & 0xff);
        }

        unsigned char get_alpha(const unsigned int i) const
        {
            return ((data_[i] >> 24) & 0xff);
        }

        void set(const unsigned char r, const unsigned char g, const unsigned char b,
                 const unsigned char a, const unsigned int i)
        {
            data_[i] = r | (g << 8) | (b << 16) | (a << 24);
        }

        unsigned int get_width() const
        {
            return width_;
        }

        unsigned int get_height() const
        {
            return height_;
        }

        void set(const unsigned int x, const unsigned int y, const unsigned int d)
        {
            data_[x + y * width_] = d;
        }

        unsigned int get(const unsigned int x, const  unsigned int y) const
        {
            return data_[x + y * width_];
        }

        unsigned int get(const unsigned int i) const
        {
            return data_[i];
        }

        const std::string &get_name() const
        {
            return name_;
        }

        unsigned int *get_data()
        {
            return &data_[0];
        }

        const unsigned int *get_data() const
        {
            return &data_[0];
        }

        // By default down sample to half of each original dimension.
        std::shared_ptr<RGBAImage> down_sample(unsigned int w=0,
                                               unsigned int h=0) const;

        void write_to_file(const std::string &filename) const;

    private:

        RGBAImage(const RGBAImage &);
        RGBAImage &operator=(const RGBAImage &);

        const unsigned int width_;
        const unsigned int height_;
        const std::string name_;
        std::vector<unsigned int> data_;
    };


    std::shared_ptr<RGBAImage> read_from_file(const std::string &filename);


    class RGBImageException : public virtual PerceptualDiffException
    {
    public:

        explicit RGBImageException(const std::string &message)
            : std::invalid_argument(message),
              PerceptualDiffException(message)
        {
        }
    };
}

#endif