// Catalano Imaging Library
// The Catalano Framework
//
// Copyright © Diego Catalano, 2012-2016
// diego.catalano at live.com
//
//    This library is free software; you can redistribute it and/or
//    modify it under the terms of the GNU Lesser General Public
//    License as published by the Free Software Foundation; either
//    version 2.1 of the License, or (at your option) any later version.
//
//    This library 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
//    Lesser General Public License for more details.
//
//    You should have received a copy of the GNU Lesser General Public
//    License along with this library; if not, write to the Free Software
//    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
//

package Catalano.Imaging.Filters;

import Catalano.Imaging.FastBitmap;
import Catalano.Imaging.IApplyInPlace;

/**
 * Desaturation.
 * 
 * 
Supported types: RGB.
 * 
Coordinate System: Independent.
 * 
 * @author Diego Catalano
 */
public class Desaturation implements IApplyInPlace{
    
    private double saturationFactor = 0.2D;

    /**
     * Get Saturation factor.
     * @return Saturation factor.
     */
    public double getSaturationFactor() {
        return saturationFactor;
    }

    /**
     * Set Saturation factor.
     * @param saturationFactor Saturation factor.
     */
    public void setSaturationFactor(double saturationFactor) {
        this.saturationFactor = Math.min(1, Math.max(0, saturationFactor));
    }

    /**
     * Initialize a new instance of the Desaturation class.
     */
    public Desaturation() {}

    /**
     * Initialize a new instance of the Desaturation class.
     * @param saturationFactor Saturation factor.
     */
    public Desaturation(double saturationFactor) {
        setSaturationFactor(saturationFactor);
    }

    @Override
    public void applyInPlace(FastBitmap fastBitmap) {
        
        if (fastBitmap.isRGB()){
            
            int size = fastBitmap.getSize();
            
            for (int i = 0; i < size; i++) {
                    
                double r = fastBitmap.getRed(i);
                double g = fastBitmap.getGreen(i);
                double b = fastBitmap.getBlue(i);

                double luminance = 0.2125D * r + 0.7154 * g + 0.0721 * b;

                double nr = (luminance + saturationFactor * (r - luminance));
                double ng = (luminance + saturationFactor * (g - luminance));
                double nb = (luminance + saturationFactor * (b - luminance));

                fastBitmap.setRGB(i, (int)nr, (int)ng, (int)nb);
                    
            }
        }
        else{
            throw new IllegalArgumentException("Desaturation only works in RGB space color.");
        }
    }
}