android2ddrawgeometric-arc

Android: looking for a drawArc() method with inner & outer radius


I have the following custom view:

alt text

This I have achieved by using the Canvas' drawArc() method. However, with this drawArc() method I cannot limit the arc's inner radius.

What I'd like to have is something like this:

alt text

where there is only an outer ring left.

What I need is an drawArc() function where I can set the inner radius of the arc. Anyone an idea how to do that?

(BTW, overpainting the inner area doesn't work, because it needs to be transparent. Painting an inner circle with Color.TRANSPARENT after painting the red and blue cones doesn't remove the old color. It just puts another layer on top, which is transparent and through which I can still see the red and blue)


Solution

  • You can paint over the inner area using the PorterDuff xfermode called "Clear." This will erase pixels.