Android Gauge Animation Question

Question

Okay so i\'ve been trying to do this for a couple of days and i am getting no where. So i have the following two images:

The First is a RPM Gauge

Answer 1

This is how to draw arcs, from Android ApiDemos: http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/Arcs.html

Then you need to use xfermode to remove a part of the top image by using a canvas derived from a bitmap. You can see one example of this approach here: Make certain area of bitmap transparent on touch