/******************************************************************
 * @(#) Animator2.java     1.0
 *
 * Copyright (c) 2002 John Miller
 * All Right Reserved
 *-----------------------------------------------------------------
 * Permission to use, copy, modify and distribute this software and
 * its documentation without fee is hereby granted provided that
 * this copyright notice appears in all copies.
 * WE MAKE 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. WE SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY ANY USER AS A RESULT OF USING,
 * MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 *-----------------------------------------------------------------
 *
 * @version     1.0, 6 March 2002
 * @author      John Miller
 */

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;

/******************************************************************
 * The Animator class demonstrates how the Java 2D API shapes can
 * be put into motion to create a simple animation.
 */
public class Animator2 extends JFrame
                    implements Runnable
{
    private static final Dimension dim = new Dimension (600, 350);
    private static final int       tau = 50;

    private final Thread           displayer;
    private Point2D.Double         ballPos;
    private Ellipse2D.Double       ball1;
    private Ellipse2D.Double       ball2;

    /**************************************************************
     * The DisplayPanel inner class is used to place shapes in the
     * drawing region.
     */
    public class DisplayPanel extends JPanel
    {
        /**********************************************************
         * Paint the display panel component.
         * @param  gr  Graphics context.
         */
        public void paintComponent (Graphics gr)
        {
           super.paintComponent (gr);
           Graphics2D gr2 = (Graphics2D) gr;
           gr2.setColor (Color.red);
           ball1.setFrame (ballPos.x, ballPos.y, 15, 15);
           gr2.fill (ball1);
           gr2.setColor (Color.blue);
           ball2.setFrame (ballPos.x + 30, ballPos.y, 15, 15);
           gr2.fill (ball2);
        } // paintComponent

    } // DisplayPanel inner class

    /**************************************************************
     * Construct an animator frame.
     * @param  title  Title of frame
     */
    public Animator2 (String title)
    {
        super (title);
        addWindowListener (new WindowAdapter () {
            public void windowClosing (WindowEvent e) { System.exit (0); }
        }); 
        ballPos = new Point2D.Double (5, 300);
        ball1   = new Ellipse2D.Double ();
        ball2   = new Ellipse2D.Double ();

        getContentPane ().add (new DisplayPanel ());
        setLocation (100, 100);
        setSize (dim);
        setVisible (true);
        displayer = new Thread (this, "displayer");
        displayer.start ();
    } // Animator2

    /**************************************************************
     * Run method for the display thread.
     * Repeatedly update coordinates, sleep and repaint.
     */
    public void run ()
    {
        for ( ; ballPos.x < 500; ballPos.x += 3) {
            ballPos.y = 50 + ((ballPos.x - 250) * (ballPos.x - 250)) / 250;
            //System.out.println (" ( " + ballPos.x + " , " + ballPos.y + " ) ");
            try {
                displayer.sleep (tau);
            } catch (InterruptedException ex) {
                System.err.println ("Animator2.run: sleep failed");
            } // try
            repaint ();
        } // for

        for ( ; ballPos.x > 5; ballPos.x -= 3) {
            ballPos.y = 50 + ((ballPos.x - 250) * (ballPos.x - 250)) / 250;
            //System.out.println (" ( " + ballPos.x + " , " + ballPos.y + " ) ");
            try {
                displayer.sleep (tau);
            } catch (InterruptedException ex) {
                System.err.println ("Animator2.run: sleep failed");
            } // try
            repaint ();  
        } // for
    } // run

    /**************************************************************
     * Main method for invoking the animator.
     * @param  args  Command-line arguments
     */
    public static void main (String [] args)
    {
        new Animator2 ("Animator2");
    } // main

} // Animator2 class