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!

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

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

here 5 is my radius.