Open Bug 1641104 Opened 4 years ago Updated 4 years ago

CSS animations on transform property triggers transition when they start/end

Categories

(Core :: CSS Transitions and Animations, defect, P3)

defect

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()

People

(Reporter: birtles, Unassigned)

Details

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(1 file)

Attached file antoine.html

In the attached test case, an attempt is made to fire a transition on the transform property while a CSS animation is running on that same property. The running CSS animation should mean no transition is fired (since it affects the before- and after-change style).

I think that part is working, however transitions are triggered when the CSS animation starts and ends. You can observe that by looking at the animation inspector as well as by observing that transitionstart and transitionend events are fired, as reported in the console.

If you change the test to use the left property, however, no transitions are fired.

I'm not sure if this is another case of us failing to update the style on the main thread for OMT animations or if it is something amiss when we compare the before-change and after-change transform styles.

(In reply to Brian Birtles (:birtles) from comment #0)

I'm not sure if this is another case of us failing to update the style on the main thread for OMT animations or if it is something amiss when we compare the before-change and after-change transform styles.

My wild guess is, it's not related to the issue. It looks like another issue in updating cascading results (or in marking cascade update necessary stuff).

But it might be possible that it's the same root cause, I mean we can't properly detect the element dirtiness in animation stuff.

The odd thing is that it works correctly for other properties like left.

So it's possibly either specific to transform values, or specific to compositor animations.

yep, what I meant is cascading check (or detecting cascading necessity) may be failing for compositor running animations in pre-traversal stuff. The failure results not flushing throttled animations (bug 1623425) not update cascading results (this). Anyway it's my guess though.

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