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Re: Concurrent loading of images ?
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Re: Concurrent loading of images ?


  • Subject: Re: Concurrent loading of images ?
  • From: Georg Seifert via Cocoa-dev <email@hidden>
  • Date: Sat, 9 May 2020 15:28:23 +0200

Have you profiled this? The first thing I would to is run that in Instruments.

Georg


> Am 9. May 2020 um 14:44 schrieb Gabriel Zachmann via Cocoa-dev
> <email@hidden>:
>
> Again, thanks a lot for all the helpful hints.
>
> Before restructuring my code, I did a few timings, using a set of test images
> ranging in size from 30 through 300 MB.
> I used mach_absolute_time() for this experiment.
> And now, I am confused.
>
> These are the execution times I have found for some of the methods that I
> invoke in the process of loading and displaying the next image:
>
> CGImageSourceCreateWithURL:         0.4-1.4 millisec
> CGImageSourceGetStatus:             10-600  microsec
> CGImageSourceCopyPropertiesAtIndex: 0.8-9   millisec
> CGImageSourceCreateImageAtIndex:    15      microsec
> convertToNSImage (*):               25      microsec
> imgLayer.contents = nsimage:        1-5     microsec
> removeFromSuperlayer:               0.1     microsec
> addSublayer:                        5-10    microsec
>
> (*): this is a wrapper method of mine that does a few calls to
> CIImage/NSImage/NSCIImageRep methods.
>
> Overall, none of the methods I invoke seems to incur a long execution time.
> Yet, there is a noticeable lag when my app switches from one image to the
> next one.
> I can tell because all layers have an animation assigned.
> Sometimes , there is even a stutter in the animation itself.
>
> But it doesn't seem like it makes sense at this point to load images in a
> concurrent/background dispatch queue, does it?
>
> So, I am confused: where is the lag coming from?
>
> Any ideas how I might be able to prevent the lag/stutter when loading and
> switching to big images?
>
>
> Best, G.
>
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References: 
 >Concurrent loading of images ? (From: Gabriel Zachmann via Cocoa-dev <email@hidden>)
 >Re: Concurrent loading of images ? (From: Jens Alfke via Cocoa-dev <email@hidden>)
 >Re: Concurrent loading of images ? (From: Rob Petrovec via Cocoa-dev <email@hidden>)
 >Re: Concurrent loading of images ? (From: Gabriel Zachmann via Cocoa-dev <email@hidden>)
 >Re: Concurrent loading of images ? (From: Alex Zavatone via Cocoa-dev <email@hidden>)
 >Re: Concurrent loading of images ? (From: Gabriel Zachmann via Cocoa-dev <email@hidden>)

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