Intent to Ship: font-variant-alternates and the @font-feature-values at-rule
Dominik Röttsches
Contact emails
dr...@chromium.orgExplainer / Specification
https://drafts.csswg.org/css-fonts-4/#font-variant-alternates-propSummary
font-variant-alternates enables simpler access to glyph alternates in fonts such as swashes, character-variants, ornaments and more. It provides an easier method over having to use 4-letter-codes (e.g. 'swsh', 'cv01'...) as arguments to font-feature-settings. font-variant-alternates refers to the @font-feature-values at-rule to map speaking feature names to OpenType feature numbers. In the font-variant-alternates style rule, the requested feature activation becomes easy to use and to read and allows flexible combination of font features.
Motivation
As part of Interop 2022 we committed to supporting font-variant-alternates and @font-feature-values in order to reach parity with Firefox and Safari on this aspect of OpenType feature selection through CSS.
The ergonomics of font-variant-alternates are better than having to know OpenType feature codes and passing them to font-feature-settings.
Blink component
Blink>FontsTAG review
Shipping in two browsers for a long time.TAG review status
Not applicableRisks
Interoperability and Compatibility
Low, extensively tested in WPT, shipped in Firefox and Safari.
Gecko: Shipped/Shipping (https://caniuse.com/?search=font-variant-alternates) Shipped in Firefox since 34.
WebKit: Shipped/Shipping (https://caniuse.com/?search=font-variant-alternates) Shipped in Safari since 9.1
Web developers: Web developers opinions were taken into account in the interop 2022 process - so I'd tend to say the fact it's part of Interop 2022 indicates: "positive".
Other signals: https://wpt.fyi/interop-2022 - font-variant-alternates amounts to 16% improvement in the Fonts and Typography Category of Interop 2022, about ~1% of the total score.
Ergonomics
This feature provides an ergonomics improvement over font-feature-settings.
Activation
Developers can immediately benefit from this feature when they write their own @font-feature-values mappings to font features, based on the font's documentation or tools such as https://wakamaifondue.com/. On top of that, if the font foundry provides a @font-feature-values block, it becomes even easier to activate font features.
WebView application risks
Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?
Debuggability
The font-variant-alternates property is debugged through DevTools as usual. This way parsing issues or invalid values can be detected. There's no extra support for the @font-feature-values rule.
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?
YesIs this feature fully tested by web-platform-tests?
YesFlag name
Atm available behind experimental web platform features (sson in Canary, from 12/8/22)Requires code in //chrome?
FalseTracking bug
https://crbug.com/716567Sample links
https://roettsch.es/montecarlo.htmlEstimated milestones
110
Anticipated spec changes
None
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5070560260784128
Philip Jägenstedt
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Chris Harrelson
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Yoav Weiss
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