Web-Facing Change PSA: Support currentcolor in Relative Color Syntax
Kevin Babbitt
Contact emails
Specification
https://www.w3.org/TR/css-color-5/#resolving-rcs
Design docs
https://docs.google.com/document/d/1568wVjrIRbrU9_O37gPu10cj0CDWRiAc6ZMk9t0JpXs/edit
Summary
Allow relative colors in CSS (using the 'from' keyword) to use 'currentcolor' as a base. This will make it easy for web developers to set complementary colors, based on an element's text color, for that element's borders, shadows, backgrounds, etc.
Blink component
TAG review
https://github.com/w3ctag/design-reviews/issues/894
TAG review status
Satisfied. The link above is for Relative Color Syntax in general. Tests for currentcolor cases were added as part of the discussion before the TAG signed off on the review; I interpret that to mean that they're satisfied with this use case.
Risks
Interoperability and Compatibility
Interoperability: Relative Color Syntax is a focus area for Interop 2024, and inclusion of currentcolor is well covered by existing WPTs, so the risk of other engines not converging on an interoperable implementation is low.
Compatibility: The only risk here is that enabling currentcolor support will "light up" color declarations that are being rejected at present. Total usage of Relative Color Syntax on the Web (including currentcolor or otherwise) is ~0.09% of page loads as of May 1, 2024[1]. I haven't done an analysis of currentcolor in RCS, but given that no major engine supported it as of that date, I would expect it to be a tiny fraction of those. [1] https://chromestatus.com/metrics/feature/timeline/popularity/4632
Gecko: Positive (https://github.com/mozilla/standards-positions/issues/841) Implementation bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1893966
WebKit: Shipped/Shipping (https://bugs.webkit.org/show_bug.cgi?id=245970) Changes landed May 13.
Web developers: Positive (https://github.com/web-platform-tests/interop/issues/426) This feature is part of Interop 2024.
Other signals:
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?
None
Debuggability
Covered by existing DevTools support for debugging CSS properties.
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
Yes
Is this feature fully tested by web-platform-tests?
Yes
Flag name on chrome://flags
None
Finch feature name
CSSRelativeColorSupportsCurrentcolor
Requires code in //chrome?
False
Tracking bug
https://issues.chromium.org/issues/325309578
Estimated milestones
|
Shipping on desktop |
129 |
|
Shipping on Android |
129 |
|
Shipping on WebView |
129 |
Anticipated spec changes
Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).
None
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5307971793059840?gate=6194544847880192
This intent message was generated by Chrome Platform Status.