How to draw a shape in Android as one of other layout objects?

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http://stackoverflow.com – I've been working on this for a while but can't find anything that exactly addresses my question (at least not something easy to understand). I have a main layout XML file where I define various layout objects like a Button or a TextView (and I know I can add SurfaceView, View, and view and other things too). I want to draw a shape (in my case it's an arc) in just one of these objects so it doesn't take up the whole screen and so I can position it relative to other things. (In my case it will ultimately re-draw the arc kind of like a circle with a gap in a different position every time I cal (HowTos)