import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;

public class ExpandingRing extends Applet
                           implements MouseListener {

   private int x = 100, y = 100;  // Coordinates of the mouse click
   private int pauseLength;       // Speed control from HTML tag

   public void init() {
      pauseLength = Integer.parseInt(getParameter("PauseLength"));
      setBackground(Color.white);
      addMouseListener(this);
   }

   public void paint(Graphics g) {
      int count = 0;
      while (count < 100) {
         int radius = 5*count;
         int diameter = 2*radius;
         g.setColor(Color.black);
         g.drawOval(x-radius, y-radius, diameter, diameter); // Draw
         pause(pauseLength);
         g.setColor(Color.white);
         g.drawOval(x-radius, y-radius, diameter, diameter); // Erase!
         count = count+1;
      }
   }
   
   private void pause(int howLong) {
      for (int count = 0; count < howLong; count++);
   }

   public void mouseClicked(MouseEvent e) {
     x = e.getX();
     y = e.getY();
     repaint();
   }

   public void mouseExited(MouseEvent e) { }

   public void mouseEntered(MouseEvent e) { }

   public void mousePressed(MouseEvent e) { }

   public void mouseReleased(MouseEvent e) { }
}