1600165 - mask-image-interpolation CSS-transition failed

Status: UNCONFIRMED

(Core :: Layout, defect, P3)

Description

[hao]

Attachment: Screenshot_2019-11-28 mask-image-interpolation.png

User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.108 Safari/537.36

Steps to reproduce:

Create a local server under wpt, and open localhost:8000/ + path to the test
Run the attached test with Firefox nightly build.

Actual results:

See the attached image.

Expected results:

Pass all the test

Comment 1

[hao]

Attachment: mask-image.tar.gz

Comment 2

[hao]

The spec is here: https://drafts.fxtf.org/css-masking-1/#the-mask-image

Comment 3

[hao]

Attachment: mask-image-test.tar.gz

Comment 4

[Florencia Di Ciocco, NI to vbalducci]

Hi ,

I wasn't able to reproduce the bug but I've chosen a component for this bug in hope that someone with more expertise may look at it. We'll await their answer. If you consider that there's another component that's more proper for this case you may change it.

Regards, Flor.

Comment 5

[Sean Voisen (:svoisen)]

Boris: Do you know if we are supposed to support mask-image transitions?

Comment 6

[Boris Chiou [:boris]]

(In reply to Sean Voisen (:svoisen) from comment #5)

Boris: Do you know if we are supposed to support mask-image transitions?

It's discrete animation (i.e. flip at 50%), based on the spec definition. So I suspect we should use test_no_interpolation() in wpt.

[css-transitions] defines transitionable: When comparing the before-change style and after-change style for a given property, the property values are transitionable if they have an animation type that is neither not animatable nor discrete.

In other words, mask-image is a non-transitionable property (i.e. its value should be flipped immediately after specifying a new one). That's why we don't pass the incorrect wpt.

Comment 7

[Boris Chiou [:boris]]

A similar case is border-image-source, whose animation type is also discrete. We use test_no_interpolation in wpt [1] and we pass all.

[1] https://searchfox.org/mozilla-central/source/testing/web-platform/tests/css/css-backgrounds/animations/border-image-source-interpolation.html

Comment 8

[Boris Chiou [:boris]]

Just notice there is a related spec issue: https://github.com/w3c/csswg-drafts/issues/4441

Comment 9

[Brian Birtles (:birtles)]

I imagine at some point that spec will be updated to interpolate using computed value so that <image> values get cross-fade() interpolation (which we don't support per bug 546052)--although there are still a few spec issues surrounding that.