camera preview覆盖图片

摘自：http://groups.google.com/group/android-developers/browse_thread/thread/0d8587b4b2139a85/6e1f453ac051f6bd?#6e1f453ac051f6bd

import android.app.Activity; 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.hardware.Camera; 
import android.os.Bundle; 
import android.view.SurfaceHolder; 
import android.view.SurfaceView; 
import android.view.View; 
import android.view.Window; 
import android.view.ViewGroup.LayoutParams; 


public class TestCameraOverlay extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 


        requestWindowFeature(Window.FEATURE_NO_TITLE); 


        Preview mPreview = new Preview(this); 
        DrawOnTop mDraw = new DrawOnTop(this); 


        setContentView(mPreview); 
        addContentView(mDraw, new LayoutParams 
(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); 


    } 



} 


class DrawOnTop extends View { 

        public DrawOnTop(Context context) { 
                super(context); 
                // TODO Auto-generated constructor stub 
        } 


        @Override 
        protected void onDraw(Canvas canvas) { 
                // TODO Auto-generated method stub 


                Paint paint = new Paint(); 
                paint.setStyle(Paint.Style.FILL); 
                paint.setColor(Color.BLACK); 
                canvas.drawText("Test Text", 10, 10, paint); 


                super.onDraw(canvas); 
        } 



} 


//---------------------------------------------------------------------- 

class Preview extends SurfaceView implements SurfaceHolder.Callback { 
    SurfaceHolder mHolder; 
    Camera mCamera; 


    Preview(Context context) { 
        super(context); 


        // Install a SurfaceHolder.Callback so we get notified when 
the 
        // underlying surface is created and destroyed. 
        mHolder = getHolder(); 
        mHolder.addCallback(this); 
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
    } 


    public void surfaceCreated(SurfaceHolder holder) { 
        // The Surface has been created, acquire the camera and tell 
it where 
        // to draw. 
        mCamera = Camera.open(); 
        mCamera.setPreviewDisplay(holder); 
    } 


    public void surfaceDestroyed(SurfaceHolder holder) { 
        // Surface will be destroyed when we return, so stop the 
preview. 
        // Because the CameraDevice object is not a shared resource, 
it's very 
        // important to release it when the activity is paused. 
        mCamera.stopPreview(); 
        mCamera = null; 
    } 


    public void surfaceChanged(SurfaceHolder holder, int format, int 
w, int h) { 
        // Now that the size is known, set up the camera parameters 
and begin 
        // the preview. 
        Camera.Parameters parameters = mCamera.getParameters(); 
        parameters.setPreviewSize(w, h); 
        mCamera.setParameters(parameters); 
        mCamera.startPreview(); 
    } 



}