2017709 - styling paused view transition animation makes it jump to the end

Status: NEW

(Core :: CSS Transitions and Animations, defect)

Description

[martin.trapp]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:149.0) Gecko/20100101 Firefox/149.0

Steps to reproduce:

• I start a same-document view transition that would take 5 seconds to move a button
• after 1 seconds, I add styling to outline the group pseudo
• after 2 seconds, I remove the styling
• after 3 seconds, I pause all animations
• after 4 seconds, add styling to outline the group pseudo
• after 5 seconds, I remove the styling
• after 6 seconds, I let all animations play to their end

codepen: https://codepen.io/editor/martrapp/pen/019c7143-052a-775e-a0e4-8c83ec578448

Actual results:

• Style change during animations works as expected.
• Style change while the animations are paused does not work as expected: The pseudo-elements jump to the end position of the animtion and stay there.
• When the animtions continue to play, the peudos jump back, continuing from the position where they were when the animation was paused.

Expected results:

in paused view transition animations, pseudos shoud stay at their position when styling changes

Comment 1

[BugBot [:suhaib / :marco]]

The Bugbug bot thinks this bug should belong to the 'Core::CSS Transitions and Animations' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Emilio Cobos Álvarez [:emilio]]

Attachment: Test-case from reporter.

I agree in principle it shouldn't jump.

Comment 3

[Emilio Cobos Álvarez [:emilio]]

Needs some debugging, we're maybe reframing, or maybe ending the animation too eagerly or something.

Comment 4

[martin.trapp]

Thank you, Emilio, for taking a look, I really appreciate it. I am not familiar with the implementation, but it might be related to copying the geometry of the new element into the group pseudo during the render loop. Perhaps an active animation then reapplies the position corresponding to the current time, whereas a paused one might not?