I tried to change the shape of some Android components like Button or View. What I can do is assign a shape to the background with the onDraw-Method. Well, it looks like reshape
You can define the shapes in xml (as you can see here). e.g. :
drawable/sample_shape.xml:
Then you can use the xml description as a drawable for an ImageButton.
drawable/samplebutton.xml:
in your layoutfile: