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;
import javax.microedition.lcdui.game.LayerManager;
import javax.microedition.lcdui.game.Sprite;
import javax.microedition.lcdui.game.TiledLayer;


public class MainCanvas extends GameCanvas implements Runnable{
	private boolean	m_bRunning;			//控制线程运行
	public TiledLayer m_TLayer;				//管理场景
	public int m_aCells[][] =              //存储m_TLayer中各cell的取值
		   {{	2,	2,	3,	2,	2,	2,	2,	2 },
			{   2,	3,	2,	4,	3,	4,	3,	2 },
			{   2,	3,	3,	3,	4,	2,	4,	2 },
			{   2,	3,	2,	3,	3,	4,	1,	2 },
			{	2,	4,	3,	3,	3,	3,	4,	2 },
			{	2,	3,	2,	3,	3,	4,	3,	2 },
			{	2,	3,	3,	4,	1,	3,	3,	2 },
			{	4,	2,	2,	4,	2,	2,	4,	4 } };
	public Sprite m_ManSprite;				//用于显示精灵动画
	public LayerManager m_Manager;			//图层管理器，管理各个图层
	public int m_nX = 0;					//显示区域左上角的横坐标
	public int m_nY = 0;   				//显示区域左上角的纵坐标
	public MainCanvas(){
		super(true);
		try{			
			//读取tile图片
			Image image = Image.createImage("/demo/map.png");
			//创建TiledLayer场景
			m_TLayer = new TiledLayer( 8, 8, image, 32, 32 ); 
			//设置场景的位置
			m_TLayer.setPosition( 0, 0 );
			LoadMap();			
			//读取精灵图片，创建精灵，精灵的像素大小为27*36
			Image image2 = Image.createImage("/demo/Man.png");
			m_ManSprite = new Sprite( image2, 27, 36 );
			//设置精灵左上角的位置		
			m_ManSprite.setPosition( 80 , 80 );	
			
			//将各个图层添入m_Manager
			m_Manager = new LayerManager();
			m_Manager.append(m_ManSprite);
			m_Manager.append(m_TLayer);
			//设置m_Manager的显示区域
			m_Manager.setViewWindow( m_nX, m_nY, getWidth(), getHeight() );
		}
		catch (IOException e){}
		Start();								//启动线程
	}
	public void LoadMap(){
		//设置m_TLayer中各cell的值
		for( int row = 0; row < 8; row ++ ){
			for( int col = 0; col < 8; col ++ ){
				m_TLayer.setCell( row, col, m_aCells[row][col] );
			}
		}
	}
	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
		//获取系统当前时间，并将时间换算成以毫秒为单位的数
		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(){
		int keyStates = getKeyStates();			//得到当前按键状态

		boolean m_bKeyDown = false;           //有无按键的标志
		//如果按下方向键的上键，则显示区域向上移动
		if( ( keyStates & GameCanvas.UP_PRESSED ) != 0 ){
			m_nY -= 2; 
			m_bKeyDown = true;
		}
		//如果按下方向键的下键，则显示区域向下移动
		if( ( keyStates & GameCanvas.DOWN_PRESSED ) != 0 ){
			m_nY += 2;
			m_bKeyDown = true;
		}	
		//如果按下方向键的左键，则显示区域向左移动
		if( ( keyStates & GameCanvas.LEFT_PRESSED ) != 0 ){
			m_nX -= 2; 
			m_bKeyDown = true;
		}
		//如果按下方向键的右键，则显示区域向右移动
		if( ( keyStates & GameCanvas.RIGHT_PRESSED ) != 0 ){
			m_nX += 2;
			m_bKeyDown = true;
		}
		if( m_bKeyDown ){
			//调整显示区域，使显示区域不超出场景
			if( m_nX < 0 )
				m_nX = 0;
			//m_TLayer中存储的场景图像的宽度为8*32，高度也为8*32
			if( m_nX > 8 * 32 - getWidth() )
				m_nX = 8 * 32 - getWidth();
			if( m_nY < 0 )
				m_nY = 0;
			if( m_nY > 8 * 32 - getHeight() )
				m_nY = 8 * 32 - getHeight();
			//重新设置显示区域
			m_Manager.setViewWindow( m_nX, m_nY, getWidth(), getHeight() );
		}
	}
	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_ManSprite.getFrame();
		n ++;
		//getFrameSequenceLength可获取精灵图像中“帧”的个数
		if( n >= m_ManSprite.getFrameSequenceLength() )
			n = 0;
		m_ManSprite.setFrame(n);
	}
	public void Paint(){
		Graphics g = getGraphics();
		//用黑色清屏
		g.setColor(0);
		g.fillRect( 0, 0, getWidth(), getHeight() );
		
		//从屏幕的(0,0)点开始显示图像
		m_Manager.paint( g, 0, 0 );
		
		flushGraphics();
	}
}