<html> <body> Hey guys, I'm testing an optimization to automatically switch from an OVER operator to SOURCE whenever the source is fully opaque. It's working very well, but I encounter a problem in the case where these three conditions are met: -the source is smaller the destination -the extend mode is none -we use the verb paint without specifying a clip area You can see the result of the filter-nearest-offset test as attachment with and without the optimization. With the optimization (Faulty.png), the last 4x4 is drawn and the SOURCE operator overwrite everything else in the image. I see two possible solutions: 1- I disable that optimization when the extend mode is at none (as there's a chance we'll sample transparent pixels outside the image) 2- The behavior shown is not the desired one and we never noticed it before because we were using an OVER operator My question is then: when painting (cairo_paint) a small source onto a larger destination, do we A) really want to sample the source for every pixel of the destination, or do we B) only want to paint the source within its bounds onto the destination (thus using its bounds as a clip area)? If the answer is A), then my second question is: do we have any better way to just paste a small source onto a larger destination (without having to define a clip area each time)? I suppose this is a very common thing to do and many users would see a speed boost. Our filter-nearest-offset is not in perf, but it would still go a lot faster if we weren't sampling (AND compositing) everywhere for each 4x4. I suspect many people would do that mistake. Antoine</body> </html>