On Android how do I make oddly shaped clipping areas?

Question

Here is how to create a clipping area the shape of a circle:

Path path = new Path();
path.addCircle(200,200,100,Direction.CW);
c.clipPath(path); // c is a Canvas         


        

Answer 1

From the Canvas javadoc:

Canvas#clipPath(Path path, Region.Op op) - Modify the current clip with the specified path.

So, for your donut example:

1. Create 2 Paths. One for the larger circle, one for the smaller circle.
2. Canvas#clipPath( Path ) with larger circle Path.

3. Call the Canvas#clipPath( Path, Region.Op ) method on your canvas with the smaller circle Path for the first argument and the appropriate Region.Op enum value for the second argument.

   Path largePath = new Path();
   largePath.addCircle(200,200,100,Direction.CW);
   Path smallPath = new Path();
   smallPath.addCircle(200,200,40,Direction.CW);
   c.clipPath(largePath); // c is a Canvas
   c.clipPath(smallPath, Region.Op.DIFFERENCE);
   

Again, modify the Region.Op enum value to get different effects...