1932814 - The Arabic text with Cursive font will fallback to Traditional Arabic font

Status: RESOLVED FIXED

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

Description

[blinky]

Steps to reproduce:

Open
data:text/html;charset=utf-8,<div style="font-family:cursive;font-size:80px">السلام عليكم

Expected result:

The Arabic text will be displayed in Arial font instead of Traditional Arabic font.

Comment 1

[blinky]

I can also reproduce with monospace font.

data:text/html;charset=utf-8,<div style="font-family:monospace;font-size:80px">السلام عليكم

Comment 2

[blinky]

Regression range:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=6840cc3786ac4ce90558c0082c0dae5cd1f997a5&tochange=73ae30d15fdda0ab65c7315f970a9d483359e29d

Regressed by: bug 1928012

Comment 3

[Jonathan Kew [:jfkthame]]

It doesn't look like we have an Arabic font configured for cursive by default: https://searchfox.org/mozilla-central/rev/5da13af5e6be251b70e994c8b4bd35fb5271f1e3/modules/libpref/init/all.js#2132-2135 shows that font.name-list.cursive.ar just lists Comic Sans, which would work for any Latin characters present in content tagged with lang=ar, but AFAIK doesn't include actual Arabic characters.

Given that, it's not clear what cursive should resolve to in Arabic; it's just a fallback of some kind. Specifying a suitable font in the font.name-list.cursive.ar pref would provide control over this.

Comment 4

[Jonathan Kew [:jfkthame]]

Regressed by: bug 1928012

Yes, the fallback rewrite in that bug did change behavior here; we previously tried Arial as a first-choice fallback for everything, whereas now we try more script-specific options first.

So basically this is suggesting -- in the absence of specific fonts being configured in the font.name-list.* prefs for these generics -- that Arial would be a preferable fallback, rather than the Traditional Arabic that we're now getting?

Comment 5

[blinky]

The Traditional Arabic font is not clear, Arial is best.

Comment 6

[Thorin [:thorin]]

Attachment: test.jpg

I'm not seeing this issue in Nightly - https://arkenfox.github.io/TZP/tests/fontdebug.html

edit: I need to learn to read expected result properly - enjoy the test page

Comment 7

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1932814 - Use Arial as default fallback font for Arabic script on Windows. r=#layout

This restores the preferred fallback font we were using prior to bug 1928012,
for better text clarity.

Comment 8

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

Set release status flags based on info from the regressing bug 1928012

Comment 9

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1932814 - Basic reftest for GetCommonFallbackFonts for Arabic on Windows. r=#layout

Not in WPT as the particular fonts used for fallback are not in any way specified
or standardized; this is just testing the particular behavior we have implemented
in Gecko (for now -- we might change the font configuration prefs in future, and
if so this test will potentially need adjusting to match).

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b6165cc77c14
Use Arial as default fallback font for Arabic script on Windows. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/b136e0dc43e3
Basic reftest for GetCommonFallbackFonts for Arabic on Windows. r=TYLin

Comment 11

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/b6165cc77c14
https://hg.mozilla.org/mozilla-central/rev/b136e0dc43e3

Comment 12

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

The patch landed in nightly and beta is affected.
:jfkthame, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox134 to wontfix.

For more information, please visit BugBot documentation.

Comment 13

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1932814 - Use Arial as default fallback font for Arabic script on Windows.

This restores the preferred fallback font we were using prior to bug 1928012,
for better text clarity.

Original Revision: https://phabricator.services.mozilla.com/D230049

Comment 14

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1932814 - Basic reftest for GetCommonFallbackFonts for Arabic on Windows.

Not in WPT as the particular fonts used for fallback are not in any way specified
or standardized; this is just testing the particular behavior we have implemented
in Gecko (for now -- we might change the font configuration prefs in future, and
if so this test will potentially need adjusting to match).

Original Revision: https://phabricator.services.mozilla.com/D230135

Comment 15

[Phabricator Automation]

beta Uplift Approval Request

• User impact if declined: Undesired fallback font choice for some Arabic content on Windows
• Code covered by automated testing: yes
• Fix verified in Nightly: no
• Needs manual QE test: no
• Steps to reproduce for manual QE testing: n/a
• Risk associated with taking this patch: minimal
• Explanation of risk level: Just a change to default fallback font for Arabic script
• String changes made/needed: none
• Is Android affected?: no

Comment 16

[Jonathan Kew [:jfkthame]]

While this isn't really a "correctness" issue, as there's no hard and fast rule about what fallback fonts should be used, in practice the changed default that resulted from the Windows font fallback rewrite was undesirable for users, so this just reverts to preferring Arial (matching our longstanding behavior).
So IMO we should uplift this to avoid shipping the unwanted change to Release for one cycle.

Comment 17

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/5c5d6766483b
https://hg.mozilla.org/releases/mozilla-beta/rev/0ede62a81bed