Intent to Extend Experiment: HTML-in-canvas

[Chromestatus]

Contact emails

chri...@chromium.org, sche...@chromium.org, p...@chromium.org, sza...@chromium.org, foo...@chromium.org

Explainer

https://github.com/WICG/html-in-canvas

Specification

https://github.com/whatwg/html/pull/11588

Summary

HTML-in-canvas enables customizing the rendering of html using canvas with three new primitives: an attribute to opt-in canvas elements (layoutsubtree), methods to draw child elements (2d: drawElementImage, webgl: texElementImage2D, webgpu: copyElementImageToTexture), and a paint event which fires to handle updates.

Blink component

Blink>Canvas

Web Feature ID

canvas

TAG review

https://github.com/w3ctag/design-reviews/issues/1204

TAG review status

Pending

Origin Trial Name

html-in-canvas

Goals for experimentation

API shape

Chromium Trial Name

HTMLInCanvas

Origin Trial documentation link

https://github.com/WICG/html-in-canvas

WebFeature UseCounter name

kHTMLInCanvas

Goals for experimentation

None

Risks

Interoperability and Compatibility

This API exposes a small amount of new information which carries an interop risk, such as the pixels of gradients and form controls.

Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1076) Mozilla did not object to advancing the spec to stage 2 (consensus around rough API shape), and we are actively working to address their concerns about fingerprinting and compatibility.

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/630)

Web developers: Positive (https://github.com/whatwg/html/issues/10650#issuecomment-3324124682) We have positive signals from users of the DevTrial: https://github.com/whatwg/html/issues/10650#issuecomment-3324124682

Other signals:

Security

https://github.com/WICG/html-in-canvas?tab=readme-ov-file#privacy-preserving-painting

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

Reason this experiment is being extended

We have received substantial feedback, have made significant changes (WebGL/WebGPU APIs, privacy), and would like to continue collecting feedback. Draft spec: https://github.com/whatwg/html/pull/11588 TAG review: https://github.com/w3ctag/design-reviews/issues/1204 Signals requests: https://github.com/mozilla/standards-positions/issues/1076, https://github.com/WebKit/standards-positions/issues/630 Outreach for feedback from the spec community: https://github.com/whatwg/html/issues/10650 WPT tests: https://wpt.fyi/results/html/canvas/element/manual/draw-element-image

Ongoing technical constraints

No information provided

Debuggability

Content under canvas can be debugged like regular DOM content via devtools.

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
https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/web_tests/wpt_internal/html/canvas/drawElementImage/

DevTrial instructions

https://github.com/WICG/html-in-canvas?tab=readme-ov-file#developer-trial-dev-trial-information

Flag name on about://flags

chrome://flags/#canvas-draw-element

Finch feature name

CanvasDrawElement

Requires code in //chrome?

False

Tracking bug

https://crbug.com/500967896

Measurement

HTMLInCanvas UseCounter

Estimated milestones

Origin trial desktop first	148
Origin trial desktop last	150
Origin trial extension 1 end milestone	154
DevTrial on desktop	138
Origin trial Android first	148
Origin trial Android last	150
DevTrial on Android	138
Origin trial WebView first	148
Origin trial WebView last	150

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5172548013916160?gate=5154315363811328

Links to previous Intent discussions

Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/a473b17f-def6-4bb7-85ee-344947c5ecabn%40chromium.org
Intent to Experiment: https://groups.google.com/a/chromium.org/g/blink-dev/c/t_nGEmJ_v4s

This intent message was generated by Chrome Platform Status.