/******************************************************************
 * @(#) Animator.java     1.0
 *
 * Copyright (c) 2007 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, 25 September 2007
 * @author      John Miller
 */

import static java.lang.System.*;
import java.awt.*;
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 Animator extends JFrame
                   implements Runnable
{
    private static final Dimension  dim = new Dimension (640, 350);
    private static final int        tau = 20;          // at 50 Hz

    private final Thread            displayer;
    private final Point2D.Double    ballPos;
    private final Ellipse2D.Double  ball;

    /**************************************************************
     * 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  The graphics context.
         */
        public void paintComponent (Graphics gr)
        {
            super.paintComponent (gr);
            Graphics2D gr2 = (Graphics2D) gr;  // use hi-res

            gr2.setPaint (Color.red);
            ball.setFrame (ballPos.x, ballPos.y, 20, 20);
            gr2.fill (ball);
        } // paintComponent

    } // DisplayPanel inner class

    /**************************************************************
     * Construct an animator frame.
     * @param  title  Title of frame
     */
    public Animator (String title)
    {
        super (title);
        setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

        ballPos = new Point2D.Double (0, 300);
        ball    = new Ellipse2D.Double ();

        getContentPane ().add (new DisplayPanel ());
        setLocation (100, 100);
        setSize (dim);
        setVisible (true);

        displayer = new Thread (this);
        displayer.start ();
    } // Animator

    /**************************************************************
     * Run method for the display thread.
     * Repeatedly update coordinates, sleep and repaint.
     */
    public void run ()
    {
        for ( ; ballPos.x <= 600; ballPos.x += 2) {

            ballPos.y = ((ballPos.x - 300) * (ballPos.x - 300)) / 300;
            // out.println (" ( " + ballPos.x + " , " + ballPos.y + " ) ");

            try {
                displayer.sleep (tau);
            } catch (InterruptedException ex) {
                out.println ("Animator.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 Animator ("Animator");
    } // main

} // Animator class