> On Nov 14, 2017, at 20:18 , Jens Alfke <j...@mooseyard.com> wrote: > > > >> On Nov 14, 2017, at 8:11 PM, Rick Mann <rm...@latencyzero.com> wrote: >> >> Maybe, at least for the bonus question. The bigger question is around the >> copy. > > Where pixmaps live is a pretty complex issue — ideally they live in the GPU’s > address space as textures so they can be blitted efficiently, and that’s > often (depending on your hardware) not accessible to the CPU at all. But > there’s a lot of logic in CoreGraphics and the underlying graphics engines to > shuffle the pixmaps back and forth so software can read and write them. > > Another factor is that the pixmap may be rescaled or translated into > different color spaces to optimize rendering it. So there may not exist a > default rendering of it at the time you request one, meaning CG will generate > a new pixmap for you. (Also, I dunno about UIImage, but NSImage supports > image formats like PDF that don’t have a native pixmap representation at all.) > > I’m not super into graphics, but my gut feeling is that, if you care about > optimization details like whether pixmaps are being copied, you should really > be using a lower-level graphics API than UIImage, which is mostly a > cheap-and-cheerful convenience layer for apps that just need to splat a few > PNGs into their GUI.
Well, then let me rephrase it as "unnecessary copies." In this case, I (currently) need to manipulate the pixels to generate a new image. I will be moving this to a Metal 2 filter soon enough, but for pre-iOS 11 users, I'd still like to use as little memory as possible (we use a lot of memory in our app). -- Rick Mann rm...@latencyzero.com _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
