size-adjust

[firefoxic]

Description

The size-adjust descriptor for the @font-face at-rule defines a multiplier for glyph outlines and metrics associated with this font, to allow the author to harmonize the designs of various fonts when rendered at the same font-size.

Specification

https://drafts.csswg.org/css-fonts-5/#size-adjust-desc

Open Issues

No response

Tests

https://wpt.fyi/results/css/css-fonts/size-adjust-01.html
https://wpt.fyi/results/css/css-fonts/size-adjust-02.html
https://wpt.fyi/results/css/css-fonts/size-adjust-03.html
https://wpt.fyi/results/css/css-fonts/size-adjust-text-decoration.tentative.html
https://wpt.fyi/results/css/css-fonts/size-adjust-unicode-range-system-fallback.html
https://wpt.fyi/results/css/css-fonts/size-adjust.tentative.html

Current Implementations

• Blink
• Gecko
• WebKit

Standards Positions

No response

Browser bug reports

https://bugs.webkit.org/show_bug.cgi?id=256081

Developer discussions

No response

Polls & Surveys

No response

Existing Usage

No response

Workarounds

No response

Accessibility Impact

No response

Privacy Impact

No response

Other

https://developer.mozilla.org/en-US/docs/Web/CSS/@font-face/size-adjust
https://caniuse.com/mdn-css_at-rules_font-face_size-adjust

[shivamidow]

I think WebKit already implemented this feature and shipped it in Safari 17 although not all tests are green. Check your setting Develop > Feature Flags after enabling the developer option.

[nt1m]

This is already implemented and mostly interoperable across browsers. Safari implemented in v17 and Safari Technology Preview.

There are 2 minor bugs that differ:

• Firefox & Safari fail: size-adjust-unicode-range-system-fallback.html
• Safari fails: size-adjust-text-decoration.tentative.html, although this is pretty trivial to fix and doesn't necessarily prevent using the feature.

[foolip]

https://wpt.fyi/results/css/css-fonts/size-adjust-01.html is failing in Chrome, and that failure is linked to https://crbug.com/451346. But that's about font-size-adjust, not sure if the failure is linked to the wrong bug or what.

[nt1m]

The Safari failure on https://wpt.fyi/results/css/css-fonts/size-adjust-text-decoration.tentative.html is due to https://bugs.webkit.org/show_bug.cgi?id=262866 which is orthogonal to the size-adjust functionality.

[nt1m]

https://wpt.fyi/results/css/css-fonts/size-adjust-01.html is failing in Chrome, and that failure is linked to https://crbug.com/451346. But that's about font-size-adjust, not sure if the failure is linked to the wrong bug or what.

It looks like the Chrome failure is just fuzziness.

[dholbert]

• Firefox & Safari fail: size-adjust-unicode-range-system-fallback.html

At least for Firefox, we're only failing on the wpt.fyi CI for some reason. The test passes in our own CI, and it passes locally on my machine. I filed https://bugzilla.mozilla.org/show_bug.cgi?id=1860124 to investigate.

(Update: it's in part due to the fact that this^ test uses a Japanese glyph that doesn't seem to be available in any system fonts, in Firefox's wpt.fyi test-runner environment. If I ensure that a system-font is available with this glyph, then we pass the test. So, our failure there is more of an environment configuration issue, not matching what the test requires in terms of system fonts, rather than a size-adjust correctness issue, I think.)

[dholbert]

The other Firefox failure here is size-adjust.tentative.html, tracked in bug 1837533, thought the failure there seems to be a subtle vertical-spacing thing -- to-be-determined whether it's a Firefox bug or a test bug, but in any case, that test-failure is unrelated to the size-adjust feature.

[gsnedders]

See https://wpt.fyi/results/css/css-fonts?label=master&label=experimental&aligned&q=size-adjust%20%21font-size-adjust for all the tests.

[shivamidow]

https://wpt.fyi/results/css/css-fonts/size-adjust-01.html is failing in Chrome, and that failure is linked to https://crbug.com/451346. But that's about font-size-adjust, not sure if the failure is linked to the wrong bug or what.

I think the failure indicates a wrong pointer. font-size-adjust is irrelevant to that test. Also, the failure on size-adjust-01.html seems limited to the Chrome product. When I tested it with a Chromium build on Linux, the test passed.

I found that size-adjust-01.html.ini has the following lines. Perhaps, the Google Chrome team has a better understanding about this.

[size-adjust-01.html]                                                                                                                                                     
  expected:                                                                                                                                                               
    if product == "chrome": FAIL

[foolip]

@shivamidow the size-adjust-01.html.ini file is just a way of recording that the failure is known and these files are generated automatically. We'd need to take a closer look at size-adjust-01.html, but as @nt1m points out it's just a very minor difference between expected and actual, so probably not very impactful.

[jgraham]

Thank you for proposing size-adjust for inclusion in Interop 2024.

We wanted to let you know that this proposal was not selected to be part of Interop this year.

This proposal was not included in Interop 2024 because when we looked at its Web Platform Tests results, we found that it is already largely interoperable between tested browsers and does not need special coordinated attention.

For an overview of our process, see proposal selection. Thank you again for contributing to Interop 2024!

Posted on behalf of the Interop team.