/*
  * File: PongApplet.java
  * Author: Java, Java, Java, 3E
  * Description:  In the game of pong a balls ricochet off
  *  the walls of a square. The paddle on the right wall is controlled by the up
  *  and down arrow keys. The ball bounces at a random angle off the
  *  paddle and the walls. This version uses double buffering to reduce
  *  flicker.
  */

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

public class PongApplet extends JApplet implements KeyListener {
     private Ball ball;
     private Paddle pad, padLeft;

     /**
      * init() creates the ball and paddle objects, and registers as the
      *  KeyListener. It also must requestFocus() so that it will receive
      *  key events.
      */
     public void init() {
         setBackground(Color.white);
         addKeyListener(this);
         pad = new Paddle(this);  // Create the paddle
         padLeft = new Paddle(this, true); // Create left paddle
         ball = new Ball(this);      // Create the ball
         ball.start();
         requestFocus();  // Required to receive key events
     } // init()

     /**
      * paint() renders the scene
      */
     public void paint (Graphics g ) {
          g.setColor(getBackground());
          g.fillRect(0,0,getWidth(),getHeight());

          /* Draw the ball */
          g.setColor(Color.blue);
          g.fillOval(ball.getX(),ball.getY(),ball.SIZE,ball.SIZE);

          /* Draw the paddles */
          pad.resetLocation();
          padLeft.resetLocationLeft();
          g.setColor(Color.red);
          g.fillRect(pad.getX(),pad.getY(),Paddle.WIDTH,Paddle.HEIGHT);
          g.fillRect(padLeft.getX(), padLeft.getY(), Paddle.WIDTH, Paddle.HEIGHT);
     } // paint()

     /**
      * hitPaddle() returns true if ball hits paddle.
      * @return -- a boolean which is true if paddle and ball are touching
      */
      public boolean ballHitsPaddle() {
          return (ball.getX() + Ball.SIZE >= pad.getX()
		  && ball.getY() >= pad.getY()
		  && ball.getY() <= pad.getY() + Paddle.HEIGHT) ||
	      (ball.getX() <= padLeft.getX() + Ball.SIZE
	       && ball.getY() >= padLeft.getY()
	       && ball.getY() <= padLeft.getY() + Paddle.HEIGHT);
     } // ballHitsPaddle()

     /**
      * keyTyped() is invoked every time a KeyEvent occurs.
      * It getscthe key's code and checks whether the up
      *   or down arrow keys were pressed. If so it moves
      *  the paddle.
      */
     public void keyPressed( KeyEvent e) { // Check for arrow keys
         int keyCode = e.getKeyCode();
         if (keyCode == e.VK_UP)            // Up arrow
             pad.moveUp();
         else if (keyCode == e.VK_DOWN)     // Down arrow
             pad.moveDown();
         else if (keyCode == e.VK_S)       // Up arrow
             padLeft.moveUp();
         else if (keyCode == e.VK_Z)     // Down arrow
             padLeft.moveDown();
     } // keyReleased()
     public void keyTyped(KeyEvent e) {}
     public void keyReleased( KeyEvent e) {} // Unused
} // PongApplet