create bitmap with alpha from multiple drawables
<p>I am drawing multiple resources  onto a bitmap via a canvas.  I would like the end result of the composite image to have a certain alpha.  Right now I'm setting paint's alpha to the level i want and then drawing each bitmap with that alpha, but i know this would create a composite image of a lot of different alphas.  Is there a way to apply an alpha to the entire composite image in performance friendly manner?</p>
