Android游戏开发：实现手势操作切换图片的实例

package com.himi;  
import java.util.Vector;  
import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.graphics.Canvas;  
import android.graphics.Color;  
import android.graphics.Paint;  
import android.util.Log;  
import android.view.GestureDetector;  
import android.view.MotionEvent;  
import android.view.SurfaceHolder;  
import android.view.SurfaceView;  
import android.view.View;  
import android.view.GestureDetector.OnGestureListener;  
import android.view.SurfaceHolder.Callback;  
import android.view.View.OnTouchListener;  
/** 
 *@author Himi 
 *@ Gesture （上文）触摸屏手势识别 
 */ 
public class MySurfaceViewAnimation extends SurfaceView implements Callback,  
    Runnable, OnGestureListener, OnTouchListener {  
  private Thread th = new Thread(this);  
  private SurfaceHolder sfh;  
  private Canvas canvas;  
  private Paint paint;  
  private Bitmap bmp;  
  private GestureDetector gd;  
  private int bmp_x, bmp_y;  
  private boolean isChagePage;  
  private Vector v_str;// 备注1  
  public MySurfaceViewAnimation(Context context) {  
    super(context);  
    v_str = new Vector();  
    this.setKeepScreenOn(true);  
    bmp = BitmapFactory.decodeResource(getResources(),  
        R.drawable.himi_dream);  
    sfh = this.getHolder();  
    sfh.addCallback(this);  
    paint = new Paint();  
    paint.setAntiAlias(true);  
    this.setLongClickable(true);  
    // setLongClickable( true )是必须的，因为 只有这样，  
    // 我们当前的SurfaceView(view)才能够处理不同于触屏形式;  
    // 例如：ACTION_MOVE，或者多个ACTION_DOWN  
    this.setOnTouchListener(this);// 将本类绑定触屏监听器  
    gd = new GestureDetector(this);  
    gd.setIsLongpressEnabled(true);  
  }  
  public void surfaceCreated(SurfaceHolder holder) {  
    // 当系统调用了此方法才创建了view所以在这里才能取到view的宽高！！有些童鞋总是把东西都放在初始化函数里！  
    // 线程最好放在这里来启动，因为放在初始化里的画，那view还没有呢,到了提交画布unlockCanvasAndPost的时候就异常啦！  
    bmp_x = (getWidth() - bmp.getWidth()) >> 2;  
    bmp_y = (getHeight() - bmp.getHeight()) >> 2;  
    th.start();  
  }  
  public void draw() {  
    try {  
      canvas = sfh.lockCanvas();  
      if (canvas != null) {  
        canvas.drawColor(Color.WHITE);// 画布刷屏  
        canvas.drawBitmap(bmp, bmp_x, bmp_y, paint);  
        paint.setTextSize(20);// 设置文字大小  
        paint.setColor(Color.WHITE);  
        //这里画出一个矩形方便童鞋们看到手势操作调用的函数都是哪些  
        canvas.drawRect(50, 30, 175,120, paint);  
        paint.setColor(Color.RED);// 设置文字颜色  
        if (v_str != null) {  
          for (int i = 0; i