1716906 - Shouldn't generate animations in the OOP iframe in the display:none tree

Status: NEW

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

Description

[Boris Chiou [:boris]]

For example:

1. parent.html

  <div style="height: 300px; display: none;">
    <iframe src="remote/index.html" width="300" height="300"></iframe>
  </div>

2. remote/index.html

<style>
  @keyframes anim {
    from { color: red; }
    to { color: blue; }
  }
</style>

<div style="width: 100px; height: 100px; animation: anim 2s;"></div>

<script>
  const anim = target.getAnimations()[0];
  console.log(anim);
</script>

Basically, we don't generate animations for better performance. Therefore, with Fission, we shouldn't have the animation object in the OOP iframe which is in the display:none tree.

However, common animations don't waste too much CPU, so I think this is not a high-priority issue. Just a backlog for this.

Comment 1

[Hiroyuki Ikezoe (:hiro)]

To be precise it's not for performance, any CSS animations/transitions in display:none subtree should NOT be generated. I suppose it's spec-ed.

Comment 2

[Boris Chiou [:boris]]

(In reply to Hiroyuki Ikezoe (:hiro) from comment #1)

To be precise it's not for performance, any CSS animations/transitions in display:none subtree should NOT be generated. I suppose it's spec-ed.

Thanks for the clarification.

From https://drafts.csswg.org/css-animations/#animations:

Setting the display property to none will terminate any running animation applied to the element and its descendants. If an element has a display of none, updating display to a value other than none will start all animations applied to the element by the animation-name property, as well as all animations applied to descendants with display other than none.

Comment 3

[Chris Peterson [:cpeterson]]

(In reply to Hiroyuki Ikezoe (:hiro) from comment #1)

To be precise it's not for performance, any CSS animations/transitions in display:none subtree should NOT be generated. I suppose it's spec-ed.

Emilio, did you recently add some code to check display:none subtree for OOP iframes? If so, Nika thinks this bug might be easy to fix.

Tracking for Fission MVP. If there is a known webcompat issue with a real site, then we should prioritize this bug sooner for Fission M8.

Comment 4

[Emilio Cobos Álvarez (:emilio)]

(In reply to Chris Peterson [:cpeterson] from comment #3)

Emilio, did you recently add some code to check display:none subtree for OOP iframes? If so, Nika thinks this bug might be easy to fix.

I did not. We have code to detect visibility of the frame (that's all the BrowserChild::IsVisible etc). But this check should be different as that would return false for frames scrolled out of view or what not.

Comment 5

[Emilio Cobos Álvarez (:emilio)]

However this is related to the work that's going on in bug 1716762, where we likely need to add something like this.

Comment 6

[Chris Peterson [:cpeterson]]

Nika says this bug probably doesn't need to block Fission MVP, so I am moving it from Fission MVP to Future.