1195142 - set CSS_PROPERTY_CREATES_STACKING_CONTEXT for the opacity property

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Per https://lists.w3.org/Archives/Public/www-style/2015Aug/0145.html we're missing the fact that will-change:opacity should force the creation of a stacking context.

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Looks like this got lost between bug 964885 comment 6 and bug 964885 comment 9.

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

It's actually not a bug because other code handles it.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=987219ca8e47

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: MozReview Request: Bug 1195142 patch 1 - Set CSS_PROPERTY_CREATES_STACKING_CONTEXT for the opacity property. r?BenWa

Bug 1195142 patch 1 - Set CSS_PROPERTY_CREATES_STACKING_CONTEXT for the opacity property.  r?BenWa

This isn't actually needed for the only caller (which ensures that
frames with will-change: opacity create a stacking context), since
nsIFrame::BuildDisplayListForChild checks HasOpacity, which checks for
NS_STYLE_WILL_CHANGE_OPACITY.  However, it's good to have the bit set
for consistency in case we use it elsewhere.

Comment 5

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Attachment: MozReview Request: Bug 1195142 patch 2 - Add reftests for will-change creating a stacking context. r?BenWa

Bug 1195142 patch 2 - Add reftests for will-change creating a stacking context.  r?BenWa

Comment 6

[Benoit Girard (:BenWa)]

Comment on attachment 8648579 [details]
MozReview Request: Bug 1195142 patch 1 - Set CSS_PROPERTY_CREATES_STACKING_CONTEXT for the opacity property.  r?BenWa

https://reviewboard.mozilla.org/r/16249/#review14517

Ship It!

Comment 7

[Benoit Girard (:BenWa)]

Comment on attachment 8648580 [details]
MozReview Request: Bug 1195142 patch 2 - Add reftests for will-change creating a stacking context.  r?BenWa

https://reviewboard.mozilla.org/r/16251/#review14519

This is good. If we want better test coverage it would probably be useful to: 1) Test more properties that don't cause a stack context, 2) Have tests that have a list of will-change properties that mix and match permutations of properties a) that cause stacking context, b) that don't cause stacking context, c) that don't exist. ni? me if you'd like more to write these.

Comment 8

[Benoit Girard (:BenWa)]

Comment on attachment 8648580 [details]
MozReview Request: Bug 1195142 patch 2 - Add reftests for will-change creating a stacking context.  r?BenWa

https://reviewboard.mozilla.org/r/16251/#review14521

Ship It!

Comment 9

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/0e3dbc9c729c
https://hg.mozilla.org/integration/mozilla-inbound/rev/0a9680123c5f

Comment 10

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/550b193f8f99

Comment 11

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/0e3dbc9c729c
https://hg.mozilla.org/mozilla-central/rev/0a9680123c5f
https://hg.mozilla.org/mozilla-central/rev/550b193f8f99