//********************************************************************
//  Rebound.java       Author: Lewis and Loftus
//
//  Esempio d'animazione e uso della classe Timer.
//********************************************************************

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import javax.swing.Timer;

public class Rebound extends Applet
{
   private final int APPLET_WIDTH = 200;
   private final int APPLET_HEIGHT = 100;

   private final int IMAGE_SIZE = 35;
   private final int DELAY = 20;

   private Timer timer;
   private Image image;
   private int x, y, moveX, moveY;

   //-----------------------------------------------------------------
   //  Inizializza l'applet e il timer per l'animazione.
   //-----------------------------------------------------------------
   public void init()
   {
      addMouseListener (new ReboundMouseListener());

      timer = new Timer (DELAY, new ReboundActionListener());
      timer.start();

      x = 0;
      y = 40;
      moveX = moveY = 3;

      image = getImage (getCodeBase(), "happyFace.gif");

      setBackground (Color.black);
      setSize (APPLET_WIDTH, APPLET_HEIGHT);
   }

   //-----------------------------------------------------------------
   //  Disegna l'immagine nella posizione corrente.
   //-----------------------------------------------------------------
   public void paint (Graphics page)
   {
      page.drawImage (image, x, y, this);
   }

   //*****************************************************************
   //  Rappresenta l'ascoltatore del mouse per l'applet.
   //*****************************************************************
   private class ReboundMouseListener implements MouseListener
   {
      //--------------------------------------------------------------
      //  Ferma e avvia il timer (e quindi l'animazione)
      //  quando il bottone del mouse viene azionato.
      //--------------------------------------------------------------
      public void mouseClicked (MouseEvent event)
      {
         if (timer.isRunning())
            timer.stop();
         else
            timer.start();
      }

      //--------------------------------------------------------------
      //  Fornisce definizioni vuote per gli i metodi evento non usati.
      //--------------------------------------------------------------
      public void mouseEntered (MouseEvent event) {}
      public void mouseExited (MouseEvent event) {}
      public void mousePressed (MouseEvent event) {}
      public void mouseReleased (MouseEvent event) {}
   }

   //*****************************************************************
   //  Rappresenta il listener per il timer.
   //*****************************************************************
   private class ReboundActionListener implements ActionListener
   {
      //--------------------------------------------------------------
      //  Aggiorna la posizione dell'immagine ed eventualmente la
      //  direzione del movimento quando il timer genera un evento azione.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
         x += moveX;
         y += moveY;

         if (x <= 0 || x >= APPLET_WIDTH-IMAGE_SIZE)
            moveX = moveX * -1;

         if (y <= 0 || y >= APPLET_HEIGHT-IMAGE_SIZE)
            moveY = moveY * -1;
    
         repaint();
      }
   }
}