Aggiunta di una ImageView rotonda alla finestra

Codice per l'aggiunta di una ImageView contenente una bitmap rotonda alla finestra.

MainActivity:

public class MainActivity extends Activity {


    Button button;
    Button button2;
    Button button3;
    ImageView imageView;
    RelativeLayout mainLayout;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button=(Button)findViewById(R.id.button);
        button2=(Button)findViewById(R.id.button2);
        button3=(Button)findViewById(R.id.button3);
        imageView=new ImageView(this);
        mainLayout=(RelativeLayout)findViewById(R.id.activity_main);

        WindowManager windowManager=(WindowManager) getSystemService(WINDOW_SERVICE);

        WindowManager.LayoutParams wParams= new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_PHONE,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT
        );

        Bitmap b= BitmapFactory.decodeResource(getResources(),R.drawable.gatto);
        RoundedImage roundedImage=new RoundedImage(this,b,200);

        windowManager.addView(roundedImage,wParams);
    }
}

RoundedImage:

public class RoundedImage extends ImageView{

    private Bitmap figura;
    private int radius;

    public RoundedImage(Context context, Bitmap figura, int radius){
        super(context);

        this.figura=figura;
        this.radius=radius;

        Bitmap bitmap=Bitmap.createBitmap(radius,radius,Bitmap.Config.ARGB_8888);

        Paint paint=new Paint();
        Canvas canvas=new Canvas(bitmap);
        canvas.drawCircle(bitmap.getWidth()/2,bitmap.getHeight()/2,bitmap.getWidth()/2,paint);

        Rect fromRect=new Rect(0,0,figura.getWidth(),figura.getHeight());
        Rect toRect=new Rect(0,0,bitmap.getWidth(),bitmap.getHeight());
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

        canvas.drawBitmap(figura,fromRect,toRect,paint);

        setImageBitmap(bitmap);

    }
}

E accidenti, se funziona!