import java.awt.Color;
import java.io.File;
import java.io.IOException;
import javax.swing.JFileChooser;
import princeton.Picture;

/**
 * Example program to show how the Picture class works and to show how to
 * iterate over all the pixels in an image to alter them.
 * <P>
 * 
 * @author ola
 * @date August 7, 2009
 * 
 */

public class ClearBitsFromImage {
    protected static JFileChooser ourOpenChooser = new JFileChooser(System
            .getProperties().getProperty("user.dir"));

    public static final int BITS_TO_CLEAR = 4;

    /**
     * Return a new color based on parameter, but in which low-order bits are
     * cleared. Number of bits cleared is specified by constant BITS_TO_CLEAR;
     * 
     * @param c
     *            is the color on which returned value is based
     * @return a color whose RGB components are based on those of parameter c,
     *         but with low-order BITS_TO_CLEAR bits cleared/zeroed in each RGB
     *         component.
     */
    public Color reduce(Color c) {

        int r = c.getRed();
        int g = c.getGreen();
        int b = c.getBlue();

        int factor = (int) Math.pow(2, BITS_TO_CLEAR);

        r = (r / factor) * factor;
        g = (g / factor) * factor;
        b = (b / factor) * factor;

        return new Color(r, g, b);
    }

    /**
     * Return a new picture based on parameter target but in which each pixel
     * has had low-order bits cleared
     * 
     * @param target
     *            is the image that's the basis for the new image
     * @return an image based on target, but in which low-order BITS_TO_CLEAR
     *         bits are cleared.
     */

    public Picture clear(Picture target) {
        int width = target.width();
        int height = target.height();

        target.show();
        Picture pic = new Picture(width, height);

        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                Color sc = target.get(i, j);
                Color cc = reduce(sc);
                pic.set(i, j, cc);
            }
        }
        return pic;
    }

    public static void main(String[] args) throws IOException {
        String fname = null;
        ourOpenChooser
                .setDialogTitle("Choose target image to reduce in quality");
        int action = ourOpenChooser.showOpenDialog(null);

        if (action == JFileChooser.APPROVE_OPTION) {
            File f = ourOpenChooser.getSelectedFile();
            fname = f.getCanonicalPath();
            Picture source = new Picture(fname);
            source.show();
            ClearBitsFromImage strip = new ClearBitsFromImage();
            Picture reduced = strip.clear(source);
            reduced.show();
        }
    }
}