Image is duplicated using setShadowLayer() in Android

I'm using the method "setShadowLayer" of the class "Paint" on Andro开发者_开发百科id to apply a shadow effect on a Bitmap image. However, instead of creating the shadow effect, the image is duplicated.

Does anyone know why this happens?

Thanks!

Just increase radius of it and it will give shadow effect:

mPaint.setShadowLayer(5, getWidth(), getHeight()-2, Color.BLUE);

here 5 is my radius.