import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import java.awt.*;

/**
   This class makes a rebound animation using the OlymipicRing object.
*/
public class OlympicRingRebound extends JApplet  
{
     /**
      Sets up the applet.
    */
    public void init()
     {
           setPreferredSize (new Dimension(WIDTH, HEIGHT));
           setBackground(Color.white);
          
          x = 0;
          y = 0;
          moveX = 3;
          moveY = 4;
    }

   /*
        Represents the action listener for the timer.
    */
    class myTimer implements ActionListener
    {
        /*
            Updates the position of the image and possibly the direction
          of movement whenever the timer fires an action event.
        */
        public void actionPerformed(ActionEvent event)
        {
            x += moveX;
              y += moveY;
    
          if (x <= 0 || x >= WIDTH - myOlympic.getWidth())
             moveX = moveX * -1;
    
          if (y <= 0 || y >= HEIGHT - myOlympic.getHeight())
             moveY = moveY * -1;
    
            repaint();
       }
    }
    
    /*
        Sets up the timmer and starts the animation when the applet starts.
    */
    public void start()
    {
        ActionListener listener = new myTimer();
        final int DELAY = 20; // Milliseconds between timer ticks
        Timer t = new Timer(DELAY, listener);
        t.start();
    }
      
    /*
        Draws the image in the current location.
    */    
    public void paint(Graphics g)
    {
        Graphics2D g2 = (Graphics2D) g;
        
        myOlympic = new OlympicRings(x, y);  
        
        myOlympic.draw(g2); // draw an olympic ring in x, y position
    }
    
    private int x;
    private int y;
    private int moveX;
    private int moveY;
    OlympicRings myOlympic;    
    public static final int WIDTH = 800, HEIGHT = 600;
}