822236 - css3 transitions are sometimes jerky

Status: RESOLVED DUPLICATE of bug 822231

(Core :: Graphics: Layers, defect)

Description

[Julien Wajsberg [:julienw]]

STR:
* go to http://everlong.org/mozilla/animation/transition.html
* click on "trigger the animation"

Expected:
* the animation is fluid

Actual:
* the animation is sometimes fluid, sometimes jerky.

Note: it's often more jerky at the first animation. If you hit reset and then trigger again, it's never as jerky.

This maybe the same problem as in Bug 822231, but I'm not sure.

Comment 1

[Julien Wajsberg [:julienw]]

Flipping the preference "layers.offmainthreadcomposition.animate-transform" to false make the problem go away, as in Bug 822231.

I know this is most probably a different bug though.

Comment 2

[Nick Cameron [:nrc]]

Hmm, so it seems that starting at scale=0 is causing the problem here. The smaller the starting scale the more broken the transition becomes. But 0 seems to be a special case. I'm not sure why this should only affect us when throttling is on and not just regular OMTA, but I'm guessing it is because without throttling the compositor gets kept inline with regular redraws from layout.

Comment 3

[Nick Cameron [:nrc]]

The fix I'm working on for 822231 fixes this problem, so I am convinced they are the same bug (actually 822231 is a little bit more complex than this one, only patch 2 is required to fix this bug).