/*
 * Pattern.java
 *
 * Copyright (C) 1998,1999 by Hiroshi Yuki.
 * All rights reserved.
 * <hyuki@hyuki.com>
 * http://www.hyuki.com/jb/
 */

import java.awt.*;
import java.applet.*;

public class Pattern extends Applet {
    final int R = 10;
    int rw = R;
    int rh = R;
    double rpar = 1.0, gpar = 1.0, bpar = 1.0;
    Dimension dim;
    Image offimg;
    Graphics offgra;

    public void init() {
        String s;
        s = getParameter("RECTWIDTH");
        if ( s != null){
            rw = Integer.parseInt(s);
        }
        s = getParameter("RECTHEIGHT");
        if ( s != null){
            rh = Integer.parseInt(s);
        }
    }
    public void start() {
        dim = size();
        offimg = createImage(dim.width, dim.height);
        offgra = offimg.getGraphics();
    }
    public boolean mouseDown(Event e, int x, int y) {
        int ex = Math.abs(x - (dim.width - rw)) / 2;
        int ey = Math.abs(y - (dim.height - rh)) / 2;
        int dist2 = ex * ex + ey * ey;
        if (-1 < dist2 && dist2 < 1) dist2 = 1;
        rpar = Math.random() * ex * ex / dist2;
        gpar = Math.random() * ex * ey / dist2;
        bpar = Math.random() * ey * ey / dist2;
        repaint();
        return true;
    }
    public void update(Graphics g) {
        paint(g);
    }
    public void paint(Graphics g) {
        if (offgra == null) return;
        for (int y = 0; y < dim.height; y += rh) {
            for (int x = 0; x < dim.width; x += rw) {
                int ex = x - (dim.width - rw) / 2;
                int ey = y - (dim.height - rh) / 2;
                int dist2 = ex * ex + ey * ey;
                int gr = (int)(dist2 * rpar) % 256;
                int gg = (int)(dist2 * gpar) % 256;
                int gb = (int)(dist2 * bpar) % 256;
                offgra.setColor(new Color(gr, gg, gb));
                offgra.fillRect(x, y, rw, rh);
            }
        }
        g.drawImage(offimg, 0, 0, this);
    }
}