Re: Throttling drawing to vertical refresh
Re: Throttling drawing to vertical refresh
- Subject: Re: Throttling drawing to vertical refresh
- From: Andreas Falkenhahn via Cocoa-dev <email@hidden>
- Date: Fri, 23 Oct 2020 17:54:34 +0200
Thanks, but once again, I still need a throttle because I obviously don't want
to call -setNeedsDisplay as often as the CPU permits, thereby causing 100% CPU
load. I still need some timer mechanism that only calls -setNeedsDisplay every
once in a while. So should I setup a timer based on the monitor's refresh
frequency rate that calls -setNeedsDisplay in intervals of the monitor's
vertical refresh rate or how is that supposed to be implemented?
On 19.10.2020 at 01:22 David Duncan wrote:
> On Oct 18, 2020, at 2:37 AM, Andreas Falkenhahn via Cocoa-dev
> <email@hidden> wrote:
> Not quite. AppKit throttle view refresh to 60fps but it certainly
> won't throttle code that changes the gfx more often than that, i.e. something
> like this
> for(;;) view.layer.contents = (id) getNextFrame();
> will hog the CPU. So I need some external timing mechanism to set
> layer.contents not more often than necessary. I need to see if CADisplayLink
> can do that...
> Instead of directly setting layer contents, call -setNeedsDisplay
> and set contents in either an override of -[CALayer display] or in
> the delegate’s -displayLayer: callout. This should have you only
> update once per commit cycle (which is typically coordinated with the refresh
> rate).
> On 16.10.2020 at 00:48 Graham Cox wrote:
> Appkit already throttles view refreshes to 60fps. There’s nothing you need to
> do.
> —Graham
> On 16 Oct 2020, at 6:13 am, Andreas Falkenhahn via Cocoa-dev
> <email@hidden> wrote:
> I'm drawing inside an NSView by simply setting its layer's contents
> to a CGImage which is updated for every frame, e.g. something like this:
> dp = CGDataProviderCreateWithData(NULL, frameBuf, frameBufSize, NULL);
> im = CGImageCreate(frameWidth, frameHeight, 8, 32,
> frameStride, theColorSpace, (CGBitmapInfo)
> kCGImageAlphaNoneSkipFirst, dp, NULL, FALSE, kCGRenderingIntentDefault);
> view.layer.contents = (id) im;
> CGImageRelease(im);
> CGDataProviderRelease(dp);
> This works fine except that there is no throttle so this will draw
> as fast as the CPU allows, which of course is a waste of CPU cycles
> because the monitor only refreshes a certain amount of times per second.
> So is there a convenient way to throttle drawing to the monitor's
> refresh rate or does this have to be done the hard way by querying
> the monitor's refresh rate and then setting up a timer which draws
> in exactly those refresh intervals or how should this be done?
> Note that I'd like to avoid using OpenGL or Metal or whatever is
> the standard nowadays but I'm mainly interested in an AppKit solution...
> --
> Best regards,
> Andreas Falkenhahn mailto:email@hidden
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--
Best regards,
Andreas Falkenhahn mailto:email@hidden
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