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Re: Is QuickLook implemented upon CGImage or CGImageSource under the hood?
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Re: Is QuickLook implemented upon CGImage or CGImageSource under the hood?


  • Subject: Re: Is QuickLook implemented upon CGImage or CGImageSource under the hood?
  • From: Oleg Krupnov <email@hidden>
  • Date: Fri, 07 Sep 2012 15:02:51 +0300

I guess I should have asked "Is QuickLook implemented upon
CGImageSource/CGImage or lower-level libraries under the hood?" I
mean, the question is not I CGImageSource vs. CGImage, but rather
CGImageSource/CGImage vs. lower-level libraries like libjpeg etc.

I tried to measure the performance of QuickLook vs CGImageSource but
it's hard to make a clean experiment. I keep getting different figures
each time. At superficial glance, it seems that they show nearly equal
performance.

But it would be really curious what libraries QuickLook uses under the hood.

Thanks!

On Fri, Sep 7, 2012 at 2:09 PM, Mike Abdullah <email@hidden> wrote:
> Your question in the subject makes little sense. CGImageSource is a means to
> create CGImages. Quick Look likely uses both therefore.
>
> Ultimately, you need to test different image loading routes to see which
> suits your needs.
>
> CGImageSourceCreateImageAtIndex
> Generates full-size images as fast as it can
>
> QLThumbnailImageCreate
> Generates thumbnails
> Might have the thumbnail already cached for speed
> Is going to spend a little time in cross-process communication
> Logs warnings if used on the main thread in my experience
> Can handle any file type, not just images
>
> CGImageSourceCreateThumbnailAtIndex
> Generates thumbnails
> Very fast
>
> On 7 Sep 2012, at 10:21, Oleg Krupnov <email@hidden> wrote:
>
> And what is the fastest method for image loading,
> QLThumbnailImageCreate or CGImageSourceCreateImageAtIndex?
>
> Thanks!
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  • Follow-Ups:
    • Re: Is QuickLook implemented upon CGImage or CGImageSource under the hood?
      • From: Mike Abdullah <email@hidden>
References: 
 >Is QuickLook implemented upon CGImage or CGImageSource under the hood? (From: Oleg Krupnov <email@hidden>)
 >Re: Is QuickLook implemented upon CGImage or CGImageSource under the hood? (From: Mike Abdullah <email@hidden>)

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