[webkit-dev] Status of multithreaded image decoding

[Maciej Stachowiak]

I that case, starting async decoding at layout time makes sense if and only if at layout to e you can predict what you will paint. I don't know enough about our rendering to know of that is the case.

 - Maciej



On Aug 12, 2012, at 5:34 PM, Peter Kasting <pkasting at chromium.org> wrote:

> On Sun, Aug 12, 2012 at 1:24 PM, Maciej Stachowiak <mjs at apple.com> wrote:
> Why not start asynchronous decoding immediately as the image is loading, and synchronize at paint time? What is the benefit of waiting until layout time to start decoding the image data?
> 
> Uninformed guess (since I haven't touched the decoders in a while), but currently we don't decode unless the image is actually painted, which helps a ton on pages that are an enormous long string of images (common cases: Boston Big Picture blog, various porn sites), since most of the images can be decoded after initial layout, or not at all (if the user never scrolls down enough).  If we started decoding as images loaded I'd imagine we'd do (possibly a lot of) extra work compared to today.
> 
> PK
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