maincanvas.java

J2ME编程的50个例子,适合掌上系统的编程

package demo;
import java.io.IOException;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.GameCanvas;

public class MainCanvas extends GameCanvas implements Runnable{
	private boolean	m_bRunning;				//控制项目运行
	private MySprite m_CockSprite;				//小鸡精灵
	private Image m_BackImg;						//背景图像
	private boolean	m_bLeft = true;				
	public MainCanvas(){
		super(true);
		try{
			//读取图片信息
			m_BackImg	= Image.createImage("/demo/back.png");
			Image image = Image.createImage("/demo/cock.png");	        
			//创建小鸡精灵			
			m_CockSprite = new MySprite( image, 95, 85 );	
			//设置精灵当前显示的“帧”编号
			m_CockSprite.setFrame( 0 );      
				
			//getWidth与getHeight可分别获取屏幕的宽度和高度	
			int nPosX = getWidth();			
			int nPosY = getHeight() - 90;	
			//设置精灵左上角的位置		
			m_CockSprite.setPosition( nPosX , nPosY );
		}
		catch (IOException e){}                //此处不进行错误处理
		Start();								//启动线程
	}
	public void Start(){
		m_bRunning = true;
		Thread thread = new Thread(this);		//分配新线程
		thread.start();							//线程启动
	}
	public void run() {						//新线程自动调用此方法
		//获得系统当前时间,并将时间换算成毫秒
		long T1 = System.currentTimeMillis();
		long T2 = T1;
		while(m_bRunning){
			T2 = System.currentTimeMillis();
			if( T2 - T1 > 100 ){			    //间隔100毫秒
				T1 = T2;
				Input();
				Logic();
				Paint();
			}
		}
	}
	public void Stop(){						//终止游戏
		m_bRunning = false;
	}
	public void Input(){
	}
	public void Logic(){
		//更换精灵当前显示的“帧”编号，“帧”编号不能大于上限
		int n = m_CockSprite.getFrame();
		n ++;
		//getFrameSequenceLength可获取精灵图像中“帧”的个数
		if( n >= m_CockSprite.getFrameSequenceLength() )
			n = 0;
		m_CockSprite.setFrame(n);
		//设置精灵的位置,如果精灵超出屏幕左侧,则让精灵从右侧重新出现
		int nPosX = m_CockSprite.getX();
		int nPosY = m_CockSprite.getY();
		if( m_bLeft ){
			m_CockSprite.setTansform(MySprite.TRANS_NONE);
			nPosX -= 3;
			if( nPosX < -95 )
				m_bLeft = false;
		}
		else{
			m_CockSprite.setTansform(MySprite.TRANS_MIRROR);
			nPosX += 3;
			if( nPosX > getWidth() )
				m_bLeft = true;
		}
		m_CockSprite.setPosition( nPosX, nPosY );
	}
	public void Paint(){
		Graphics g = getGraphics();
		//用黑色清屏
		g.setColor(0);
		g.fillRect( 0, 0, getWidth(), getHeight() );
		
		//显示背景,并将背景图像的中心点对应到屏幕中心点
		int nPosX = getWidth()/2 - 100;			
		int nPosY = getHeight()/2 - 100;	
		g.drawImage( m_BackImg, nPosX, nPosY, 0);
		
		//显示精灵的当前“帧”
		m_CockSprite.paint(g);
		
		flushGraphics();
	}
}