[webkit-reviews] review requested: [Bug 22108] REGRESSION: Animated gifs sometimes don't animate (wunderground.com weather radar) : [Attachment 25693] patch v1

[bugzilla-daemon at webkit.org]

Peter Kasting <pkasting at google.com> has asked Dave Hyatt <hyatt at apple.com> for
review:
Bug 22108: REGRESSION: Animated gifs sometimes don't animate (wunderground.com
weather radar)
https://bugs.webkit.org/show_bug.cgi?id=22108

Attachment 25693: patch v1
https://bugs.webkit.org/attachment.cgi?id=25693&action=review

------- Additional Comments from Peter Kasting <pkasting at google.com>
hyatt and I have already chatted some on IRC about this patch.

This fixes animations by not deleting the decoder, meaning the loop count can
stay valid across frames.  I didn't actually determine for sure that this was
the problem in CG WebKit, but it was the problem in Chromium, and patching the
fix in here made the testcases seem to work in my Safari Win build.

It turns out the CG decoder was already doing a pretty good job of dropping
frames when their external references were released, and of deleting frames
internally during re-decoding, so it didn't suffer from the peak memory issues
Cairo/Chromium did, and the old "delete ImageDecoder" code wasn't really
necessary for it at all.  Unfortunately it also decodes from the beginning of
the stream more than it needs to, so it still uses far more CPU than it should
(i.e. this patch does not fix the underlying problem in bug 22280).  Perhaps
hyatt can use the framework in this patch to help address things.