1324966 - Need a method to get nsStyleContext* without computing the style for a given property which is animating

Status: RESOLVED WONTFIX

(Core :: CSS Parsing and Computation, defect, P3)

Description

[Hiroyuki Ikezoe (:hiro)]

The methods is necessary to get the base style for the target element of animations.

It will be similar to nsStyleContext::ResolveStyleWithoutAnimation() but without nsStyleContext* argument. Also it requires to skip FileRules()[1] for animations and transitions level in nsStyleSet::ResolveStyleFor() because FileRules() for those level ends up calling KeyframeEffectReadOnly::ComposeStyle().

[1] https://hg.mozilla.org/mozilla-central/file/7083c0d30e75/layout/style/nsStyleSet.cpp#l1366

Comment 1

[Hiroyuki Ikezoe (:hiro)]

(In reply to Hiroyuki Ikezoe (:hiro) from comment #0)
> The methods is necessary to get the base style for the target element of
> animations.
> 
> It will be similar to nsStyleContext::ResolveStyleWithoutAnimation() but
> without nsStyleContext* argument. Also it requires to skip FileRules()[1]
> for animations and transitions level in nsStyleSet::ResolveStyleFor()
> because FileRules() for those level ends up calling
> KeyframeEffectReadOnly::ComposeStyle().

We might need just another variant of nsComputedDOMStyle::GetStyleContextForElement() that replaces 
 ResolvePseudoElementStyle[1] and ResolveStyleFor[2] with ResolveStyleWithoutAnimation()

[1] https://hg.mozilla.org/mozilla-central/file/f179934df0c1/layout/style/nsComputedDOMStyle.cpp#l495
[2] https://hg.mozilla.org/mozilla-central/file/f179934df0c1/layout/style/nsComputedDOMStyle.cpp#l498

Comment 2

[Hiroyuki Ikezoe (:hiro)]

After some thought, the method we need should skip only an nsCSSPropertyID that passed to the method, not skipping all of animation properties.
Fortunately, we have already passed an nsCSSPropertyIDSet, which contains property set to be skipped, to KeyframeEffectReadOnly::ComposeStyle()[1], so we can just add the target nsCSSPropertyID in the set.  I am really surprised that Brian suggested to use nsCSSPropertyIDSet, he is the wizard of animation!

[1] https://hg.mozilla.org/mozilla-central/file/5ea0c495d3b2/dom/animation/KeyframeEffectReadOnly.h#l292

Though we still need to pass the nsCSSPropertyID to EffectCompositor::ComposeAnimationRule() somethow.

Comment 3

[Joel Maher ( :jmaher ) (UTC -8)]

Thanks for filing this :hiro- is there someone who could work on this bug in the coming weeks?

Comment 4

[Hiroyuki Ikezoe (:hiro)]

Honestly, this is a tough work, I am hoping I can take time to fix in this Q1, but I am less sure. That's being said, I came up with some ideas to reduce that failure (bug 1244897) frequency.   I will post a comment there soon.

Comment 5

[Hiroyuki Ikezoe (:hiro)]

I will mark this invalid once we drop gecko style system in bug 1395112.

Comment 6

[Hiroyuki Ikezoe (:hiro)]

Closing we already dropped the old style system.