[Webkit-unassigned] [Bug 42390] Multi-layer backgrounds repaint (in low quality) every 0.5 seconds

Thu Sep 16 14:33:22 PDT 2010

https://bugs.webkit.org/show_bug.cgi?id=42390

--- Comment #16 from Stephen White <senorblanco at chromium.org>  2010-09-16 14:33:22 PST ---
(In reply to comment #15)
> (In reply to comment #14)
> > I can't repro this on r67642 using Safari, nor Chrome or Chrome's test_shell.  Andreas, is there some other way I can reproduce this?
> 
> Just repro'd on ToT Qt. Are you sure that you can't reproduce? Perhaps it's just more apparent on Qt since the difference between low and high quality scaling is very noticeable with QPainter.

Hmm, I still can't see the difference visually, but setting some breakpoints reveals that the timer is definitely firing repeatedly.  (Chrome has some further criteria for drawing high quality in platform/graphics/skia which may be obscuring the result, although it's usually pretty easy to see in Safari).

It definitely looks like there are some ping-pong effects going on here.  I don't know how much time I'll have to look into this just now, so if you want to go ahead and commit your patch in the interim (with the fixes Darin suggested), I'm ok with that.  Perhaps leave a comment suggesting that this is only an interim fix until we track down why it's ping-ponging in this case.

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