/*
 * Copyright (c) 1995, 1996 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 */
import java.awt.*;
import java.applet.Applet;

/* 
 * This applet animates graphics that it generates.  This example
 * isn't a good one to copy -- it flashes.  The next couple of examples 
 * will show how to eliminate the flashing.
 */

public class FlashingGraphics extends Applet implements Runnable {
    int squareSize;
    int frameNumber;
    int delay;
    Thread animatorThread;
    boolean fillColumnTop = true;
    int fps;

    public void init() {
        String str;

        // How many milliseconds between frames?
        str = getParameter("fps");
        try {
            fps = (str != null) ? Integer.parseInt(str) : 10;
        } catch (Exception e) {
            fps = 10;
        }
        delay = (fps > 0) ? (1000 / fps) : 100;

        // How many pixels wide is each square?
        str = getParameter("squareWidth");
        try {
            squareSize = (str != null) ? Integer.parseInt(str) : 20;
        } catch (Exception e) {
            squareSize = 20;
        }
    }

    public void start() {
        if (animatorThread == null) {
            animatorThread = new Thread(this);
            animatorThread.start();
        }
    }

    public void stop() {
        animatorThread = null;
    }

    public boolean mouseDown(Event e, int x, int y) {
        if (animatorThread == null) {
            start();
        }
        else {
            stop();
        }
        return false;
    }

    public void run() {
        // Remember the starting time
        long startTime = System.currentTimeMillis();

        while (Thread.currentThread() == animatorThread) {
            // Display the next frame of animation.
            repaint();

            // Delay depending on how far we are behind.
            try {
                startTime += delay;
                Thread.sleep(Math.max(0, 
                                      startTime-System.currentTimeMillis()));
            } catch (InterruptedException e) {
                break;
            }

            frameNumber++;
        }
    }

    public void paint(Graphics g) {
        Dimension d = size();
        boolean fillSquare;
        boolean fillNextFrame;
        int rowWidth = 0;
        int x = 0, y = 0;
        int w, h;
        int tmp;

        // Set width of first "square". Decide whether to fill it.
        fillSquare = fillColumnTop;
        fillColumnTop = !fillColumnTop;
        tmp = frameNumber % squareSize;
        if (tmp == 0) {
            w = squareSize;
            fillNextFrame = !fillSquare;
        } else {
            w = tmp;
            fillNextFrame = fillSquare;
        }

        // Draw from left to right.
        while (x < d.width) {
            int colHeight = 0;

            //Draw the column.
            while (y < d.height) {
                colHeight += squareSize;

                // If we don't have room for a full square, cut if off.
                if (colHeight > d.height) {
                    h = d.height - y;
                } else {
                    h = squareSize;
                }

                // Draw the rectangle if necessary.
                if (fillSquare) {
                    g.fillRect(x, y, w, h);
                    fillSquare = false;
                } else {
                    fillSquare = true;
                } 

                y += h;
            } // while y

            // Determine x, y, and w for the next go around.
            x += w;
            y = 0;
            w = squareSize;
            rowWidth += w;
            if (rowWidth > d.width) {
                w = d.width - x;
            }
            fillSquare = fillColumnTop;
            fillColumnTop = !fillColumnTop;
        } // while x
        fillColumnTop = fillNextFrame;
    }
}