On Tue, 2010-06-29 at 10:04 +0300, Alexander Shulgin wrote: > The other day I was using Alt+TAB to switch between windows in my > brand new Ubuntu desktop and was unpleasantly surprised how window > thumbnails quality was in striking contrast with the overall eye-candy > of the desktop (other effects seem to use OpenGL).
I think pixman and cairo are pretty irrelevant for this. Window downscaling for previews needs to: A) Leave the images in video memory B) Be fast and hardware accelerated The basic way that GPU's sample images is bilinear sampling. As we see with Cairo currently, that doesn't work nicely once you are scaling down more than a factor of two. In a normal game, the way that things work is that the game provides a version of the image with multiple level of details (a mipmap) and the GPU picks the closest one to avoid large amounts of scaling. Or there are extensions for automatic mipmap generation. Automatic mipmap generation doesn't really mix with the "texture_from_pixmap" extension used for OpenGL compositors in X. (Certainly not any of the free drivers), but it's possible to emulate the effect with a bit of programming. I wrote code to do this for Mutter, the GNOME 3 window manager. The effect isn't as good as you could do with real high quality filtering, but it's vastly better than what you are seeing. - Owen _______________________________________________ Pixman mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/pixman
