gamecanvas.java

一个基于J2ME的pacman游戏

/**
 * PacMan for J2ME Devices
 * CS 327 - Design Project, Fall 2002
 * University of Illinois, Urbana-Champaign
 * 
 * file: GameCanvas.java 
 * contact: Braden Kowitz
 * date: 11/24/02
 **/

//----------------------------------------------------------------------------//

import javax.microedition.lcdui.*;

/**
 * This class is derived from a MIDlet canvas.
 * It contains the main functionality of the game.
 * It does three things basically
 * -# Contains A GameBoard, which contains the game primitives and drawing code.
 * -# Runs a FrameTrigger, which spawns a thread to periodically
 *    update the frames.
 * -# Listens for key-presses, and notifies apropriate objects in the gameboard.
 **/
public class GameCanvas extends javax.microedition.lcdui.Canvas 
{	
	/**
	 * The default display for this midlet.
	 * This variable is assigned during object construction.
	 **/
	private Display disp_;
	
	/**
	 * The game board contains the game primitives, logic, and drawing code.
	 * This object is created during construction.
	 **/
	private GameBoard gameBoard_;
	
	/**
	 * frameTrigger object is responsible for periodically calling back to
	 * this object to trigger a frame update.
	 **/
	private FrameTrigger frameTrigger_;
	
	/**
	 * Add this in attempts to get back to the intro screen
	 */
	private pacman parentApp_;

	/**
	 * Constructor.
	 * @param disp The display where the game should run.
	 **/
	public GameCanvas(pacman app, Display disp)
	{
		this.parentApp_ = app;
		disp_ = disp;
		gameBoard_ = GameBoardFactory.test();
		//frameTrigger_ = new FrameTrigger(this, 50);
	}

	/**
	 * Called by the system to repaint the screen.
	 * @param g Graphics object where drawing should take place.
	 **/
	protected void paint(Graphics g)
	{
		// clear the screen:
		g.setColor(255,255,255);
		g.fillRect(0,0,this.getWidth(),this.getHeight());

		// draw the board
		gameBoard_.paint(g);
	}

	/**
	 * Stops the frame trigger thread
	 */
	public void destroyFrameTrigger()
	{
		frameTrigger_.stopTrigger();
	}

	/**
	 * Shows the gameboard and starts the game.
	 **/
	public void show()
	{
		disp_.setCurrent(this);
		frameTrigger_ = new FrameTrigger(this, 50);
		frameTrigger_.startTrigger();
		frameTrigger_.start();
	}

	/**
	 * This function is called periodically by FrameTrigger.
	 * It simply tells the gameboard to advance it's logic
	 * by one frame, then it requests a repaint from the system.
	 **/
	public void advanceFrame()
	{
		if (gameBoard_.advanceFrame())
		{
			parentApp_.gameOver =0;
			repaint();
		}
		else
		{
			destroyFrameTrigger();
			parentApp_.gameOver = 1;
			System.out.println("set gameover to 1");
			try {
				//parentApp_.gameOver = 1;
				parentApp_.restartApp();
			} catch (javax.microedition.midlet.MIDletStateChangeException midException) {
				midException.printStackTrace();
				System.exit(1);
			}
		}
	}

	/**
	 * This function is called by the system when the user
	 * presses a key.
	 * @param keyCode The unique int value of the key being pressed'
	 * 
	 * Modified: 3/4/03 : Paul Force
	 *	Changed to use a more general key binding.  Should work
	 *    on any phone now
	 **/
	protected void keyPressed(int keyCode)
	{
		int action = getGameAction(keyCode);

		switch (action)
		{
			case UP:
			  gameBoard_.getPacman().setDesiredDirection(
			    PacmanActor.UP);
			break;

			case DOWN:
			  gameBoard_.getPacman().setDesiredDirection(
			    PacmanActor.DOWN);
			break;

			case LEFT:
			  gameBoard_.getPacman().setDesiredDirection(
			    PacmanActor.LEFT);
			break;

			case RIGHT:
			  gameBoard_.getPacman().setDesiredDirection(
			    PacmanActor.RIGHT);
			break;
		}
	}
}

//----------------------------------------------------------------------------//