1504884 - Change AnimationInfo::mAnimationGeneration to Maybe<uint64_t> to represent the state there is actually no animation

Status: RESOLVED FIXED

(Core :: DOM: Animation, enhancement, P3)

Description

[Hiroyuki Ikezoe (:hiro)]

While I was debugging the patch for bug 1504065, I noticed that we sometimes apply unwanted change hints in RestyleManager::AddLayerChangesForAnimation() because AnimationInfo::GetGenerationFromFrame returns 0 even if the layer has no animation.  This situation happens when we created a layer for a display item (corresponding to a css property) but the layer has no animation, e.g. will-change property is specified.

Comment 1

[Hiroyuki Ikezoe (:hiro)]

Attachment: An example to see this issue

I can come up with any ideas to write automated test cases for this, so I am going to attach an example to observe the issue on debugger.

The example has an element having an opacity animation and fixed transform style rotate(360deg).  We generate a transform layer and an opacity layer for this element respectively.  When we call RequestRestyle(Layer), we increase the generation on RestyleManager, and unfortunately at the time, the animation generation of the opacity layer is zero, and it will never be increased since there is no opacity animation on the layer.  Thus, every time we call RequestRestyle(Layer) we generate nsChangeHint_UpdateOpacityLayer, it's unwanted change hint.

Comment 2

[Hiroyuki Ikezoe (:hiro)]

(In reply to Hiroyuki Ikezoe (:hiro) from comment #1)
> Created attachment 9022809 [details]
> An example to see this issue
> 
> I can come up with any ideas to write automated test cases for this, so I am
> going to attach an example to observe the issue on debugger.

I *can't*

Comment 3

[Hiroyuki Ikezoe (:hiro)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=8582351503a6b79ee30b37e40618a2dd4f905a0a

Comment 4

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 1504884 - Drop AnimationInfo::mLayerManager. r?birtles!

It's not used at all.

Comment 5

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 1504884 - Wrap AnimationInfo::mAnimationGeneration into Maybe<> and returns Nothing() if there is no animation. r?birtles!

So that we don't generate anymore unnecessary change hints in
RestyleManager::AddLayerChangesForAnimation for the layer has no corresponding
animations.

Depends on D11105

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/bf7b500919fe
Drop AnimationInfo::mLayerManager. r=birtles
https://hg.mozilla.org/integration/autoland/rev/88a82ede1bc4
Wrap AnimationInfo::mAnimationGeneration into Maybe<> and returns Nothing() if there is no animation. r=birtles

Comment 7

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/bf7b500919fe
https://hg.mozilla.org/mozilla-central/rev/88a82ede1bc4