capturing screen in android

        setContentView(R.layout.main);
        bn=(Button)findViewById(R.id.button1);
        iv=(ImageView)findViewById(R.id.imageView1);
       
        bn.setOnClickListener(new OnClickListener(){

            public void onClick(View v) {
            // TODO Auto-generated method stub
            View v1=bn.getRootView(); //gives total view
            v1.setDrawingCacheEnabled(true);
            Bitmap bm=v1.getDrawingCache();
            if(bm!=null){
            iv.setImageBitmap(bm);
            }
            }

        });