Replaying recording surfaces with OVER has far worse performance than when using the SOURCE operator
Submitted by Emanuele Aina
Assigned to Chris Wilson @ickle
Description
I have some code that collects some partial redrawing of a surface in a recording surface and then later replays it on the target surface.
I've noticed that when using the OVER operator the replay is surprisingly slow, ie. the overhead over painting directly on the target is noticeable.
When using the SOURCE operator things get back to my expectations and the overhead is negligible, but unfortunately the SOURCE operators clears the target surface, destroying all the areas that don't get redrawn and thus making it unfit for my purposes.
I'd like to have a way to replay the recording surface without any clearing and without any intermediate surface.
Shouldn't the OVER operator do that? In what cases replaying directly on the target would differ from replaying to an intermediate surface and composite it with OVER?
Version: 1.12.16