package swingExamples;

import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JApplet;
import javax.swing.JPanel;
import javax.swing.Timer;

class SimpleAnimationDisplayPanel extends JPanel
    implements ActionListener
{
  public SimpleAnimationDisplayPanel()
  {
    setBackground(Color.BLACK);
    // This timer "goes off" every 10 milliseconds
    Timer timer = new Timer(10, this);
    timer.start();
  }
  
  public void paintComponent(Graphics g)
  {
    super.paintComponent(g);
    
    g.setXORMode( getBackground() );
    g.setColor(Color.RED);
    g.fillRect(m_squareX, m_squareY, m_squareSize, m_squareSize);
    g.setColor(Color.GREEN);
    g.fillOval(m_ballX + m_ballDiameter / 2, m_ballY + m_ballDiameter / 2,
        m_ballDiameter, m_ballDiameter);
  }
  
  public void actionPerformed(ActionEvent event)
  {
    // Do the animation by using XOR mode and repeated
    // repaints, modifying the coordinates of the shapes
    // between repaints.
    int width = getWidth();
    repaint();
    m_ballX++;
    if (m_ballX > width)
      m_ballX = 0;
    m_ballY++;
    if (m_ballY > width)
      m_ballY = 0;
    
    m_squareX--;
    if (m_squareX < 0)
      m_squareX = width;
    m_squareY++;
    if (m_squareY > width)
      m_squareY = 0;
    repaint();
  }
  
  ///// Private data /////
  
  // Coordinates of the ball and square to animate.
  private int m_ballX = 0;
  private int m_ballY = 0;
  private int m_ballDiameter = 30;
  private int m_squareX = 200;
  private int m_squareY = 0;
  private int m_squareSize = 50;
}

public class SimpleAnimationDisplayApplet extends JApplet
{
  public SimpleAnimationDisplayApplet()
  {
    Container contentPane = getContentPane();
    contentPane.add(new SimpleAnimationDisplayPanel());
  }
}