racergamecanvas.java

Programming java 2 microedition symbian os一书中作者编写的一个赛车游戏的半成品

/*
 * Copyright 2003, 2004 Symbian Ltd.
 * For License terms see http://www.symbian.com/developer/techlib/codelicense.html
 */

package demoracer;

/**
 * <p>Title: DemoRacer</p>
 * <p>Description: Game API Demo for Symbian MIDP 2.0 Book.</p>
 * @author Alan Newman - [e-mail]
 * @version 1.0
 */


/*
 * This is the class that provides the graphical context for the app.
 * It implements the runnanble interface to provide the thread which makes the animation
 * it also instatiates the LayerManager class which manages the sprites
 * it also creates an "Exit" command which has to be homebaked due to the Canvas being set to "Full".
 */
import javax.microedition.lcdui.game.*;
import javax.microedition.lcdui.*;
import java.io.IOException;

public class RacerGameCanvas extends GameCanvas implements Runnable {
    private RacerMidlet midlet;
    private RacerLayerManager layerManager;
    private Thread thread;
    private boolean running;
    private final int SLEEP = 0;
    
    public RacerGameCanvas(RacerMidlet midlet) throws IOException {
        super(false);
        this.midlet = midlet;
        layerManager = new RacerLayerManager(this);
    }
    
    public boolean isRunning(){return running;}
    
    synchronized void start() {
        running=true;
        thread=new Thread(this);
        thread.start();
    }
    
    public void run() {
        Graphics graphics=getGraphics();
        try {
            while (running) {
                // draw the current frames for each of the Sprites on screen
                paint(graphics);
                flushGraphics();
                // set the next frame to be displayed and reposition if required.
                layerManager.tick();
                Thread.sleep(SLEEP);
            }
        }catch(InterruptedException ie) {
            System.out.println(ie.toString());
        }
    }
    
    synchronized void stop() {
        running=false;
    }
    
    public void paint(Graphics g) {
        layerManager.draw(g);
    }
    
    public void keyPressed(int keyCode) {
        //Because the GameCanvas as been set to full screen we cannot add Comands to it
        //(think this is a bug). Therefore we have had to make our own "Exit" command to
        //exit from the MIDlet. This basically detects whether the left hand soft key has
        //been pressed and exits the MIDlet.
        if(keyCode==-6) {
            midlet.releaseResource();
            midlet.notifyDestroyed();
        }
    }
    
}