[Webkit-unassigned] [Bug 90375] Parallel image decoders

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=90375





--- Comment #54 from Huang Dongsung <luxtella at company100.net>  2012-08-01 18:20:47 PST ---
(In reply to comment #52)
> Now that I have drafted patch to remove currentFrameHasAlpha() and understand the problem better I'm going back to our discussion before.
> 
> I think having a wrapper class is fine, as long as there's only one way to trigger image decoding, i.e. nativeImageForCurrentFrame().

Yes, we use the wrapper class only with nativeImageForCurrentFrame() and GraphicsContext::draw().


> > I think your concern is in that ImageSource delegates ImageDecoder to ParallelImageDecoder. Maybe because ImageSource must directly call ImageDecoder::frameHasAlphaAtIndex and other metadata query functions.
> > If ParallelImageDecoder creates its own ImageDecoder, it will be ok.
> 
> My concern here is to have a simpler interface and contract between classes, and having fewer asynchronous interfaces helps. My suggestion is to keep ImageDecoder synchronous but ImageSource doing the work to make things parallel.

Frankly, I don't understand fully what you concerned. Our parallel image decoder implementation keeps ImageDecoder synchronous. Our implementation introduced ParallelImageDecoder, and ParallelImageDecoder has asynchronous API, because ParallelImageDecoder decodes image asynchronously. I think it is the implementation detail of ImageSource, and other classes can not know what is ParallelImageDecoder.
If I may misunderstand your opinion, could you feedback to me again?

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