Android 游戏开发 SurfaceView框架

SurfaceView和View的明显不同在于Surface不需要通过线程来更新视图，但在绘制之前必须使用lockCanvas方法锁定画布，并得到画布，然后绘制，完成后用unlockCanvasAndPost方法解锁画布。SurfaceView类的事件处理和View一样。
绘制界面的类：
package com.yarin.Android.Examples_05_02;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class GameSurfaceView extends SurfaceView
                             implements SurfaceHolder.Callback,Runnable
{
    //控制循环
    boolean            mbLoop            = false;
  
    //定义SurfaceHolder对象
    SurfaceHolder    mSurfaceHolder    = null;
    int                miCount            = 0;
    int                y                = 50;

    public GameSurfaceView(Context context)
    {
        super(context);

        // 实例化SurfaceHolder
        mSurfaceHolder = this.getHolder();

        // 添加回调
        mSurfaceHolder.addCallback(this);
        this.setFocusable(true);

        mbLoop = true;
    }

    // 在surface的大小发生改变时激发
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
    {

    }

    // 在surface创建时激发
    public void surfaceCreated(SurfaceHolder holder)
    {
        //开启绘图线程
        new Thread(this).start();
    }

    // 在surface销毁时激发
    public void surfaceDestroyed(SurfaceHolder holder)
    {
        // 停止循环
        mbLoop = false;
    }

    // 绘图循环
    public void run()
    {
        while (mbLoop)
        {
            try
            {
                Thread.sleep(200);
            }
            catch (Exception e)
            {
              
            }
            synchronized( mSurfaceHolder )
            {
                Draw();
            }
          
        }
    }

    // 绘图方法
    public void Draw()
    {
        //锁定画布，得到canvas
        Canvas canvas= mSurfaceHolder.lockCanvas();

        if (mSurfaceHolder==null || canvas == null )
        {
            return;
        }
      
        if (miCount < 100)
        {
            miCount++;
        }
        else
        {
            miCount = 0;
        }
        // 绘图
        Paint mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setColor(Color.BLACK);
        //绘制矩形–清屏作用
        canvas.drawRect(0, 0, 320, 480, mPaint);
        switch (miCount % 4)
        {
        case 0:
            mPaint.setColor(Color.BLUE);
            break;
        case 1:
            mPaint.setColor(Color.GREEN);
            break;
        case 2:
            mPaint.setColor(Color.RED);
            break;
        case 3:
            mPaint.setColor(Color.YELLOW);
            break;
        default:
            mPaint.setColor(Color.WHITE);
            break;
        }
      
        canvas.drawCircle((320 – 25) / 2, y, 50, m