Intent to Ship: Captured Surface Control
Elad Alon
Contact emails
elad...@chromium.org, gui...@chromium.org
Explainer
https://github.com/w3c/mediacapture-surface-control/blob/main/README.md
Specification
https://w3c.github.io/mediacapture-surface-control
Design docs
https://docs.google.com/document/d/10UojDvTJ6ojBEOP7cgBIIaE7WZEfes_Qv1eN3A2A0nM/edit?usp=sharing
Summary
A Web API that allows Web applications to:
1. Forward wheel events to a captured tab.
2. Read and change the zoom level of a captured tab.
Blink component
TAG review
https://github.com/w3ctag/design-reviews/issues/962
TAG review status
Issues addressed
Origin Trial Name
Captured Surface Control
Chromium Trial Name
CapturedSurfaceControl
WebFeature UseCounter name
kCapturedSurfaceControl
Risks
Interoperability and Compatibility
Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1061) The request for a standards position has no official position. Both on that issue and in the WebRTC WG, Mozilla's representative supported the use case; but of the issues he had filed against the spec, some remain without consensus.
WebKit: No signal (https://github.com/WebKit/standards-positions/issues/388) The request for a standards position has no official position. In the WebRTC WG, Apple's representative supported the use case; but of the issues he had filed against the spec, some remain without consensus.
Web developers: Strongly positive (https://docs.google.com/document/d/1CyKBeo2tGsp_k2HhK6WjDM4dciWEbejUTflKrOVYFvM/edit?usp=sharing)
Security
https://w3c.github.io/mediacapture-surface-control/#privacy-and-security-considerations
WebView application risks
N/A - this feature is built on top of screen-capture, which is not currently supported on mobile platforms.
Debuggability
N/A
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?
No
Supported on all desktop platforms. (Screen-sharing is not currently supported on mobile platforms.)
Is this feature fully tested by web-platform-tests?
No. Given the interaction with the user, the browser's own UX, and between the capturing and captured tabs, browser tests produced more meaningful coverage. Substantial coverage of that form exists over multiple unit tests and end-to-end browser tests.
Flag name on about://flags
captured-surface-control
Finch feature name
CapturedDisplaySurface
Tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=1466247
Launch bug
https://launch.corp.google.com/launch/4268170
Sample links
https://captured-surface-control.glitch.me
Estimated milestones
Anticipated spec changes
Additional gestures (in addition to scrolling) may be supported in the future, if the need is articulated by Web developers, and subject to a separate privacy/security review of those particular gestures.
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5092615678066688?gate=5158502187663360
Links to previous Intent discussions
Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAMO6jDPSgR3kX39drHd9t-JvTKBk%2B7Dg03O6dvowzw-LjQ__1A%40mail.gmail.com
Intent to Experiment: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw-DF_BCtdwiaYqrXsan3YNBfT2pAeboT0f1F9wmViPPWQ%40mail.gmail.com
Intent to Extend Experiment 1: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAMO6jDN%3DJteucLtF5RU%2Bvx9Fbc_CBifdWzjGjtW1Z5zqhcvqgA%40mail.gmail.com
Intent to Extend Experiment 2: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra9vLNpe45swTf1Bgm1ZbH%3DhBt0iAjN_FK49Y%3DznEea3vg%40mail.gmail.com
Intent to Extend Experiment 3: https://groups.google.com/a/chromium.org/g/blink-dev/c/7MbIEBdHMck/m/UBbWTX-hAgAJ
This intent message was generated by Chrome Platform Status.
Domenic Denicola
Elad Alon
The remaining open issues are:
Whether the API shape should already support gestures other than wheel, or whether such a future extension should only be addressed in the future.
Whether the API should allow concurrent forwarding events from multiple source elements or just a single one.
Whether the API should explicitly limit forwarding to the intersection of the source element and a relevant rendering element, or whether this is up to the user agent.
Whether the API should be exposed on CaptureController, or exposed on HTMLVideoElement and HTMLCanvasElement.
During multiple OT extensions, we have made multiple compromises that have closed other issues. However, when it comes to these 4 issues, our suggested compromise that completely accommodated 1-3, was rejected on the grounds that it does not also fix #4. We do not believe that further progress on these issues is possible at this time.
We are confident that any future changes to this API will be compatible with what we are shipping now.
Alex Russell
Domenic Denicola
Chris Harrelson
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