Ready for Developer Testing: Enhanced Canvas TextMetrics

[Chromestatus]

Contact emails

jlav...@google.com, andres...@chromium.org, fma...@chromium.org, sche...@chromium.org

Explainer

https://github.com/fserb/canvas2D/blob/master/spec/enhanced-textmetrics.md
https://github.com/Igalia/explainers/blob/main/canvas-formatted-text/text-metrics-additions.md
https://github.com/whatwg/html/issues/10677

Specification

https://github.com/whatwg/html/pull/11000

Summary

Expand the TextMetrics Canvas API to support selection rectangles, bounding box queries, and glyph cluster-based operations. This new functionality should enable complex text editing applications with accurate selection, caret positioning, and hit testing. Additionally, cluster-based rendering facilitates sophisticated text effects such as independent character animations and styling.

Blink component

Blink>Canvas

Web Feature ID

No information provided

Risks

Interoperability and Compatibility

These are new features and we will get vendor agreement at WHATWG before shipping. So minimal interop risks beyond platform-specific metrics differences.

Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1144)

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/436)

Web developers: Positive Developers want the ability to animated glyphs independendly (such as exploding sentences) and the ability to do e.g. selection on canvas text. The proposed APIs support these use cases and more.

Other signals:

Ergonomics

None.

Activation

None.

Security

There is always a fingerprinting concern with HTML canvas. THe new features expose no novel fingerprinting surface (text metrics are already a fingerprinting concern).

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?

No information provided

Debuggability

DevTools supports querying the APIs by default.

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
html/canvas/[element|offscreen]/text... 2d.text.measure.index-from-offset* 2d.text.measure.selection-rects* 2d.text.measure.text-clusters*

Flag name on about://flags

Experimental Web Platform Features

Finch feature name

ExtendedTextMetrics

Requires code in //chrome?

False

Tracking bug

https://issues.chromium.org/issues/341213359

Measurement

UMA counters will be added for the new APIs.

Estimated milestones

DevTrial on desktop	141
DevTrial on Android	141

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5075532483657728

Links to previous Intent discussions

Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CADgYMVdqo4PBs4OkGqVncRizs8vtX4YtFLDcK%2BRxdYo_wnaRJQ%40mail.gmail.com

This intent message was generated by Chrome Platform Status.