[Webkit-unassigned] [Bug 100257] Don't fire requestAnimationFrame for scripts in frames that are out of view

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=100257


Darin Adler <darin at apple.com> changed:

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--- Comment #13 from Darin Adler <darin at apple.com>  2012-11-08 07:25:21 PST ---
(From update of attachment 171278)
View in context: https://bugs.webkit.org/attachment.cgi?id=171278&action=review

>>> Source/WebCore/dom/ScriptedAnimationController.cpp:123
>>> +    }
>> 
>> Two things seem not quite right to me.
>> 
>> 1)  I don’t think that windowClipRect(false).isEmpty() is the correct visibility check; I can’t find any other code that’s using that and this can’t be the only place we care about visibility.
>> 2) I don’t think that polling is the right way to detect when the frame becomes visible again. We want to actively trigger it rather than running the timer over and over again.
> 
> I spent a lot of time reading the code to try and understand the rendering process; I found windowClipRect in use in ScrollView::scrollContents to determine the visible part of the window. If there's a better method to use, I'm happy to change it; I just wasn't able to find a better choice myself.

OK. That’s a fine explanation for why you did what you did, but not reason to land this patch as-is. We need to find others expert on this enough that they can help us find the right way to do it.

We do want this behavior change, but we need a correct implementation.

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