Take a look at the android.graphics.drawable.ShapeDrawable class and the Shape class subclasses, suchs as:
- PathShape
- RectShape
- ArcShape
- OvalShape
- RoundRectShape
ShapeDrawable receives a shape in the constructor, and then you have a lot of function to modify the shape. Also, you can retrieve the Paint asociated to the ShapeDrawable so you can alter things like the color and so.
Also, take a look at this small example:
http://www.edumobile.org/android/android-tutorial/shape-drawing-example-in-android/
where you can see some diferent shapes, and some efects suchs as the CornerPathEffect,