SurfaceView 透明和半透明

import android.app.Activity;  
import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.graphics.Canvas;  
import android.graphics.PixelFormat;  
import android.os.Bundle;  
import android.view.MotionEvent;  
import android.view.SurfaceHolder;  
import android.view.SurfaceHolder.Callback;  
import android.view.SurfaceView;  
  
public class TransParentActivity extends Activity {  
    /** Called when the activity is first created. */  
    class MySurfaceView extends SurfaceView implements Callback{  
        float left,top;  
        Bitmap bitmap=BitmapFactory.decodeResource(getResources(), R.drawable.reen);  
        public MySurfaceView(Context context) {  
            super(context);  
            // TODO Auto-generated constructor stub  
            <span style="color:#ff0000;">getHolder().setFormat(PixelFormat.TRANSPARENT);//设置为透明  
            //getHolder().setFormat(PixelFormat.TRANSLUCENT);//半透明   
            getHolder().addCallback(this);  
            setFocusable(true);  
        }  
  
        @Override  
        public void surfaceChanged(SurfaceHolder holder, int format, int width,  
                int height) {  
            // TODO Auto-generated method stub  
              
        }  
  
        @Override  
        public void surfaceCreated(SurfaceHolder holder) {  
            // TODO Auto-generated method stub  
         doDraw();    
        }  
  
        private void doDraw() {  
            // TODO Auto-generated method stub  
            Canvas canvas=getHolder().lockCanvas();  
            canvas.drawBitmap(bitmap, left, top, null);  
            getHolder().unlockCanvasAndPost(canvas);  
        }  
  
        @Override  
        public void surfaceDestroyed(SurfaceHolder holder) {  
            // TODO Auto-generated method stub  
              
        }  
          
        /* (non-Javadoc) 
         * @see android.app.Activity#onTouchEvent(android.view.MotionEvent) 
         */  
        @Override  
        public boolean onTouchEvent(MotionEvent event) {  
            // TODO Auto-generated method stub  
            left=event.getX();  
            top=event.getY();  
            doDraw();  
              
            return super.onTouchEvent(event);  
        }  
    }  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(new MySurfaceView(getApplicationContext()));  
          
    }  
      
} 

<?xml version="1.0" encoding="utf-8"?>  
<manifest xmlns:android="<a href="http://schemas.android.com/apk/res/android">http://schemas.android.com/apk/res/android</a>"  
      package="rw.Trans"  
      android:versionCode="1"  
      android:versionName="1.0">  
    <uses-sdk android:minSdkVersion="10" />     <application android:icon="@drawable/icon" android:label="@string/app_name">  
        <activity android:name=".TransParentActivity"  
                  android:label="Transparent SurfaceView"  
                 android:theme="@android:style/Theme.Translucent"  
                  >                     
            <intent-filter>  
                <action android:name="android.intent.action.MAIN" />  
                <category android:name="android.intent.category.LAUNCHER" />  
            </intent-filter>  
        </activity>     </application>  
</manifest>