> On Aug 24, 2016, at 12:59 PM, Jeff Szuhay <j...@szuhay.org> wrote: > > >> On Aug 24, 2016, at 10:37 AM, Jean-Daniel Dupas <mail...@xenonium.com >> <mailto:mail...@xenonium.com>> wrote: >> >>> Moreover, the performance will greatly depends the sampling algorithm you >>> choose. CGImage provide a couple of algorithms with different tradeoff (see >>> CGContextSetInterpolationQuality() and NSImage and UIImage equivalents). >> >> Just for the record, here is a link with different technics available on OS >> X to do that: >> >> http://nshipster.com/image-resizing/ <http://nshipster.com/image-resizing/> > > Yeah, but CoreImage is a different kettle of fish. CoreImage has deprecated > the creation of a core image from layers, in favor of bitmaps and > static image sources. > > I’m writing an app for Mac OS X/macOS using primarily CoreGraphics and > Quartz2D with a smattering of image filters for special effects. > I draw my images (clocks) into a “reference” sized rectangle—for simplified > position calculations—and then have CoreGraphics scale into the destination > view rect. > > On my rather old but quite functional 2007 MBP, I notice a considerable > difference in CPU use when the clocks are on the laptop main screen (low CPU) > versus on a 2nd monitor (high CPU—about 4x). I’ve surmised that the main > screen is GPU assisted wheres the 2nd monitor is not. Same clock, just on > different screens. I have yet to test whether this will be true on newer > MacBookPros with different video cabling/interfaces. > > I’m in the process of converting my clocks to draw exclusively into offscreen > layers (instead of drawing their parts into the device context directly), > composing them only when needed, and finally drawing into the view’s graphic > context. This, as we’ll soon see, depends upon how efficient the > CGContextDrawLayerInRect is when the sour layer and target context are of > different sizes—in a single call. > > Now I’m wondering if an intermediate transformation to scale the layer to the > same size as the context and then just call CGContextDrawLayerAtPoint would > be more efficient. > > And, yeah, I’m trying to trade off CPU work for GPU work, and get more work > done on the GPU. >
Oh, maybe I spoke too soon… Reading the Interpolation section in Programming With Quartz _______________________________________________ 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
