Contact emails
[email protected], [email protected], [email protected], 
[email protected]


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 eg 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.

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