1364273 - stylo: Initial value of mask-repeat should be repeat instead of no-repeat

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, enhancement)

Description

[Xidorn Quan [:xidorn] UTC+11]

This is revealed by test layout/style/test_computed_style.html that there is a difference between Stylo and Gecko that Gecko fails to serialize the computed value of mask shorthand there.

It is because Gecko checks whether all subproperties of mask except mask-image are initial for serializing the computed value [1].

This check fails for "mask: url(#mask)" because in Stylo, mask-repeat is set to "no-repeat" for initial, while Gecko checks it against "repeat".

The spec seems to agree with Servo that initial value of mask-repeat is "no-repeat", and it specially notes that its initial value is different from background-repeat (which is "repeat").

However, although Blink doesn't have mask-repeat, its initial value of -webkit-mask-repeat seems to be "repeat", which matches Gecko.

It is unclear to me whether we should change Gecko to match the spec (and Servo) or we should change Servo (and spec) to match Gecko and Blink.

[1] https://dxr.mozilla.org/mozilla-central/rev/3b96f277325747fe668ca8cd896d2f581238e4ee/layout/style/nsComputedDOMStyle.cpp#6361-6377

Comment 1

[Xidorn Quan [:xidorn] UTC+11]

CJ, what do you think about this?

Comment 2

[Cameron McCormack (:heycam)]

Per bug 1346193 the WG agreed to change the initial value to "repeat", but the spec change still hasn't been made yet.

Comment 3

[Xidorn Quan [:xidorn] UTC+11]

Ok, so we should change Stylo to match the resolution.

Comment 4

[u459114]

Attachment: Bug 1364273 - Change mask-repeat initial value from no-repeat to repeat.

Review commit: https://reviewboard.mozilla.org/r/139176/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/139176/

Comment 5

[Cameron McCormack (:heycam)]

Comment on attachment 8867611 [details]
Bug 1364273 - Change mask-repeat initial value from no-repeat to repeat.

https://reviewboard.mozilla.org/r/139176/#review142402

::: commit-message-e66de:1
(Diff revision 1)
> +Bug 1364273 - Change mask-repeat initial value from no-preat to repeat.

no-repeat

Comment 6

[u459114]

Comment on attachment 8867611 [details]
Bug 1364273 - Change mask-repeat initial value from no-repeat to repeat.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/139176/diff/1-2/

Comment 7

[u459114]

https://github.com/servo/servo/pull/16864

Comment 8

[u459114]

Attachment: Bug 1364273 - (followup) update stylo-failures.md to reduce failure count of mask.

Review commit: https://reviewboard.mozilla.org/r/139514/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/139514/

Comment 9

[u459114]

Comment on attachment 8867976 [details]
Bug 1364273 - (followup) update stylo-failures.md to reduce failure count of mask.

https://reviewboard.mozilla.org/r/139514/#review142858

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/6028e667129f
(followup) update stylo-failures.md to reduce failure count of mask. r=cjku

Comment 11

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/6028e667129f