I have got a Canvas. Its associated Bitmap is some image (see 1st image).
On top of that (see 4th image), I want to draw a part (see 3rd image) of a Bitmap (see 2nd image).
Now, I could create a cropped version of the bitmap. But that would require me to copy the entire Bitmap (which I would need to do many times each frame).
From what I have seen, PorterDuff doesn't really help either as using a pattern-Bitmap to cut the unwanted pixels after drawing would remove the original image below.
Is there any efficient way of "telling android what pixels of the bitmap to draw"? I am thinking of something like an implementation of an interface that takes an x- and y- coordinate and returns a boolean of whether to paint the according pixel.