Android SurviceView的触控和轨迹球事件

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceView;

public class Touch_TrackActivity extends Activity {
/** Called when the activity is first created. */
class MYSurFaceView extends SurfaceView{
float x;
float y;
Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.chart_pie);//用Bitmap获取Android图标

public MYSurFaceView(Context context) {
super(context);
setFocusable(true);//使用Key event,setFocusable(true)可以聚焦
// TODO Auto-generated constructor stub
}

@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
x=event.getX();//获取触控的X坐标
y=event.getY();//获取触控的Y坐标
Draw();
return true;
}

@Override
public boolean onTrackballEvent(MotionEvent event) {
// TODO Auto-generated method stub
x=event.getX();//获取轨迹的X坐标
y=event.getY();//获取轨迹的Y坐标
Draw();
return true;
}
private void Draw()
{
Canvas canvas=getHolder().lockCanvas();//定义Canvas，用SurfaceHolder的lockCanvas()方法锁住画布
canvas.drawBitmap(bitmap, x, y,null);//绘画
getHolder().unlockCanvasAndPost(canvas);//解锁画布
}
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MYSurFaceView(this));
}
}