1837272 - abspos placeholder between adjacent inline elements prevents `text-transform:capitalize` from working on the second one

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, defect)

Description

[Chris]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/113.0
Firefox for Android

Steps to reproduce:

Create a list of links:
<a href="#">about</a>
<a href="#">blogs</a>
<a href="#">contact</a>

Apply text-transform: capitalize:
a{
text-transform: capitalize;
position: relative;
}
Add a pseudo-element "::after":
a::after{
content: "";
position: absolute;
inset: 0;
outline:1px dashed red;
}

Note - this only happens on the "after" pseudo-element. When using "before" the capitalisation occurs correctly.

Actual results:

Only the first anchor text got the capitalization.
All other links remained in lower case

Expected results:

The first letter of each word should be capitalized

Comment 1

[Simona Badau, Desktop QA]

Setting this issue to Core > CSS Parsing and Computation component, to allow our engineers to take a closer look at it. If this is not the right component, please assign a more appropriate one. Thanks!

Comment 2

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

Thanks for the bug report! I can reproduce. Here's a testcase, not using ::after but instead just using an actual element in place of the pseudo-element that ::after generates. So: this isn't specific to pseudo-elements. It seems to be related to the absence of whitespace, too, as shown when comparing the upper vs. lower half of this testcase.

It looks like when we've got two inline elements side by side, we treat each one as being a capitalizeable word. But when we've got an abspos element spliced between them with no whitespace, then we treat the second one as if it weren't a new word.

Comment 3

[Daniel Holbert [:dholbert]]

This seems to be a regression, though it's an old one.

Regression range:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=257f2c96cef502a1d674df56c8e39d76d8ed4d89&tochange=aaae630f30291056f4f40bbd9e12a917309e401e

Looks like a regression from bug 1418472. jfkthame, maybe you could take a look?

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1418472

Comment 5

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1837272 - patch 1 - Ensure the 8-bit version of nsLineBreaker::AppendText clears the word-continuation flag on encountering space. r=#layout-reviewers

The issue here was that the 8-bit version of AppendText failed to reset the flag on space.
Where text-transform:capitalize is applied to a multi-word chunk of text, this wasn't an issue
because AppendText delegates to the more comprehensive 16-bit version whenever capitalization
is requested, so only that version cares about the word-continuation flag.

However, in this case the whitespace between the spans does not itself have the capitalization
property set, and so it doesn't go via the 16-bit function, and we failed to clear the flag.

Comment 6

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1837272 - patch 2 - Clean up some trivial code-style violations in nsLineBreaker. r=#layout-reviewers

No functional change, just cleaning up minor code formatting issues I noticed while reading this file.

Depends on D183251

Comment 7

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1837272 - patch 3 - Add the testcase here as a WPT reftest. r=#layout-reviewers

Depends on D183252

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9733569bfd85
patch 1 - Ensure the 8-bit version of nsLineBreaker::AppendText clears the word-continuation flag on encountering space. r=emilio
https://hg.mozilla.org/integration/autoland/rev/a7a9a2467492
patch 2 - Clean up some trivial code-style violations in nsLineBreaker. r=emilio
https://hg.mozilla.org/integration/autoland/rev/e3c9958afc20
patch 3 - Add the testcase here as a WPT reftest. r=emilio

Comment 9

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

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/40989 for changes under testing/web-platform/tests

Comment 10

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/9733569bfd85
https://hg.mozilla.org/mozilla-central/rev/a7a9a2467492
https://hg.mozilla.org/mozilla-central/rev/e3c9958afc20

Comment 11

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

Upstream PR merged by moz-wptsync-bot