1411922 - [css-text-decor-4] Implement text-decoration-skip-ink

Status: VERIFIED FIXED

(Core :: Layout: Block and Inline, enhancement, P3)

Description

This bug is meant for the implementation of the text-decoration-skip-ink property defined in the CSS Text Decoration Module Level 4:

https://drafts.csswg.org/css-text-decor-4/#text-decoration-skip-ink-property
[EDIT by dholbert: updating link to point to "*-skip-ink" rather than more-general hypothetical "*-skip" property]

Google intends to ship support for it in Chrome:
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/47BHtmz0jVY

Sebastian

Comment 1

[Sebastian Zartner [:sebo]]

See https://twitter.com/malyw/status/928250363647610881.

Sebastian

Comment 2

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

Duplicate of bug 812990?

Comment 4

[Dominik Moritz]

Chrome beta has implemented this and skips ink for underlined text automatically.

Comment 5

[Jean-Yves Perrier [:teoli]]

Paul Irish created an interactive example for text-decoration-skip-ink on MDN: https://developer.mozilla.org/en-US/docs/Web/CSS/text-decoration-skip-ink

Comment 8

[ebrahim]

As https://bugs.chromium.org/p/chromium/issues/detail?id=581456 it is implemented and made default later so now Chrome (Opera/Edge) and Safari supports it but Firefox don't.

Comment 9

[Jonathan Kew [:jfkthame]]

A couple notes that may be helpful as a starting point:

See https://bugs.chromium.org/p/chromium/issues/detail?id=581456#c24 for
the heart of Blink's implementation. In brief, if skip-ink is in effect,
the InlineTextBoxPainter::paintDecorations method calls
TextPainter::clipDecorationsStripe each time it's going to paint a
decoration line. This is responsible for getting the "intercepts"
(coordinates where the glyph outlines in the text run intersect with the
intended decoration line) and clipping out those areas.

For where the ability to get intercepts (based on Skia APIs) was added
to Chromium's Font, see
https://bugs.chromium.org/p/chromium/issues/detail?id=655166.

See also https://bugs.chromium.org/p/chromium/issues/detail?id=581456#c8
for a link back to the underlying Skia facilities they're using.

Comment 10

[fantasai]

I'll also note that the spec is not entirely up-to-date or worked out on this feature. :( Don't expect it to be a reliable reference.

Comment 11

[Charlie Marlow [:cmarlow]]

Attachment: Bug 1411922: Part 1: Add rendering support for text-decoration-skip-ink r?jfkthame

Comment 12

[Charlie Marlow [:cmarlow]]

Attachment: Bug 1411922: Part 2: Added reftests for text-decoration-skip-ink r?jfkthame

Comment 13

[Charlie Marlow [:cmarlow]]

https://treeherder.mozilla.org/#/jobs?repo=try&selectedJob=260235273&revision=620b92d1d2f7500956eaedf5b6bdac698c0fa58a

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/61f08c7faaca
Part 1: Add rendering support for text-decoration-skip-ink r=jfkthame
https://hg.mozilla.org/integration/autoland/rev/5a8a2d0bc859
Part 2: Added reftests for text-decoration-skip-ink r=jfkthame

Comment 15

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/18318 for changes under testing/web-platform/tests

Comment 16

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream web-platform-tests status checks passed, PR will merge once commit reaches central.

Comment 17

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/61f08c7faaca
https://hg.mozilla.org/mozilla-central/rev/5a8a2d0bc859

Comment 18

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged

Comment 19

[Sebastian Zartner [:sebo]]

I've tested the feature right now in the latest Nightly and at first sight it looks great! Thank you for implementing it!

I've also already created a PR for updating the browser compatibility info on MDN:
https://github.com/mdn/browser-compat-data/pull/4587

And I have updated https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Experimental_features#text-decoration-skip-ink accordingly.

Charlie, do you plan to ship this in 70 or are there any things this should wait for?

Sebastian

Comment 20

[Charlie Marlow [:cmarlow]]

We are planning to wait to ship it in Firefox 71. Because it's on by default, we want to have a full cycle to monitor potential performance issues. Thanks for updating the MDN pages!

Comment 21

[Xidorn Quan [:xidorn] UTC+10]

Maybe better enable that in Nightly since now, so that you have an even longer time to monitor issues.

Comment 22

[Daniel Holbert [:dholbert]]

(In reply to Xidorn Quan [:xidorn] UTC+10 from comment #21)

Maybe better enable that in Nightly since now, so that you have an even longer time to monitor issues.

Good idea. I filed bug 1572800 on doing this.

Comment 23

[Sean Voisen (:svoisen)]

(In reply to Daniel Holbert [:dholbert] (mostly AFK Aug 8th-12th) from comment #22)

(In reply to Xidorn Quan [:xidorn] UTC+10 from comment #21)

Maybe better enable that in Nightly since now, so that you have an even longer time to monitor issues.

Good idea. I filed bug 1572800 on doing this.

Yes, let's please do this. We won't have much time in the Nightly cycle at this point since soft freeze is only a few weeks away, but better than nothing.

Comment 24

[Chris Mills [:cmills]]

Documented; see https://bugzilla.mozilla.org/show_bug.cgi?id=1573631#c14