1505200 - The getComputedStyle() should return none If both from value and to value are 'none' for rotate

Status: RESOLVED FIXED

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

Description

[Boris Chiou [:boris]]

The spec [1] says:

> When translate, rotate or scale are animating or transitioning,
> and the from value or to value (but not both) is none, the
> value none is replaced by the equivalent identity value
> (0px for translate, 0deg for rotate, 1 for scale).

This means we shouldn't convert the `none` into the identity value if both from value and to value are `none`. (I guess this may affect the creation of stacking context during animation?). The related wpt is [2].

[1] https://drafts.csswg.org/css-transforms-2/#valdef-translate-none
[2] https://searchfox.org/mozilla-central/rev/b096dcf0ea226af628fe03f7e7acb56a25853533/testing/web-platform/tests/css/css-transforms/animation/translate-interpolation.html#64-75

Comment 1

[Brian Birtles (:birtles, Feb 26~ parental leave)]

It shouldn't affect the stacking context during animation. So long as there is a scheduled, running, or filling animation, there should be a stacking context as per:

"While an animation is applied but has not finished, or has finished but has an animation-fill-mode of forwards or both, the user agent must act as if the will-change property ([css-will-change-1]) on the element additionally includes all the properties animated by the animation."[1]

and:

"For every property targeted by at least one animation effect that is current or in effect, the user agent must act as if the will-change property ([css-will-change-1]) on the target element includes the property."[2]

[1] https://drafts.csswg.org/css-animations/#animations
[2] https://drafts.csswg.org/web-animations-1/#side-effects-section

Comment 2

[Boris Chiou [:boris]]

Attachment: Bug 1505200 - Part 1: Rewrite the interpolation of Rotate to return correct type.

It both from value and to value are none, we don't have to convert it
into identity value, so just return None. We have done this for
translate and scale in other bugs.

Comment 3

[Boris Chiou [:boris]]

Attachment: Bug 1505200 - Part 2: Serialize Rotate by servo.

So we can drop a lot of code.

Depends on D11247

Comment 4

[Boris Chiou [:boris]]

Attachment: Bug 1505200 - Part 3: Parse any order of number and angle for Rotate.

Rotate accepts rotate axis and angle in any order
(i.e. <number>{3} <angle> or <angle> <number>{3}), so we rewrite the
parser.

Comment 5

[Boris Chiou [:boris]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=3004573b068619ea02472d69f048848e08cdbc91

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f94bba680dc2
Part 1: Rewrite the interpolation of Rotate to return correct type. r=birtles
https://hg.mozilla.org/integration/autoland/rev/3bd1f4cc8f9e
Part 2: Serialize Rotate by servo. r=emilio
https://hg.mozilla.org/integration/autoland/rev/36e5bf9afd50
Part 3: Parse any order of number and angle for Rotate. r=emilio

Comment 7

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/f94bba680dc2
https://hg.mozilla.org/mozilla-central/rev/3bd1f4cc8f9e
https://hg.mozilla.org/mozilla-central/rev/36e5bf9afd50