[Webkit-unassigned] [Bug 65645] Scroll animator changes to nail the framerate

Wed Aug 3 16:05:13 PDT 2011

https://bugs.webkit.org/show_bug.cgi?id=65645

--- Comment #4 from James Robinson <jamesr at chromium.org>  2011-08-03 16:05:13 PST ---
(In reply to comment #3)
> Ah, so the idea would be to register an animation callback with the parent Document's ScriptedAnimationController instead of using the Timer directly?

Yep.

> Are the frame rate tolerances for that tighter than for what I'm doing with Timer? This gets the Timer use behaving pretty nicely.

The ScriptedAnimationController callbacks are tied directly into the paint/compositing loops and are vsync-driven when GPU composited.  Timers have no explicit links to the rendering loop, so they just fire whenever.  This might line up with the display loop, or (much more likely) it might have all sorts of aliasing issues if it's close to but not exactly synchronized with the display loop.  Think lots and lots of dropped and doubled frames.

One major difference is that the ScriptedAnimationController callbacks will not fire if the tab is not visible, so you need to be aware of that in your logic.

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