RestrictionTarget: fromElement() static method
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
The fromElement()
static method of the RestrictionTarget
interface returns a RestrictionTarget
instance that can be used to restrict a captured video track to a specified DOM element (plus its descendants).
Syntax
RestrictionTarget.fromElement(element)
Parameters
element
-
A reference to an
Element
that you want to use as a restriction target. For an element to be used as a restriction target, it must:- Form a stacking context.
- Be flattened in 3D space (for example, it is not subjected to any 3D transforms).
- Be rendered (for example, not be off-screen or hidden via
display: none
). - Contain only one box fragment (for example, not be broken across multiple lines).
If it does not meet the above criteria, it is considered to be not eligible for restriction.
In addition, the element will not be captured if the track being restricted has clones (that is, created by
BrowserCaptureMediaStreamTrack.clone()
) or is captured from a different tab to the current user's tab (passed viaWindow.postMessage()
, for example).
Note: When the element is captured, any alpha-channel value set on it is not included. If the restriction target element is semi-transparent, it will end up completely opaque in the capture and therefore end up looking different.
Return value
A Promise
that resolves to a RestrictionTarget
object instance, which can then be passed to BrowserCaptureMediaStreamTrack.restrictTo()
to restrict the video captured in the track to just the particular DOM element the RestrictionTarget
was created with.
RestrictionTarget
objects are serializable. They can be passed to another document using mechanisms such as Window.postMessage()
.
The promise will reject if the restriction target element is not eligible for restriction.
Examples
// Options for getDisplayMedia()
const displayMediaOptions = {
preferCurrentTab: true,
};
// Create restriction target from DOM element
const demoElem = document.querySelector("#demo");
const restrictionTarget = await RestrictionTarget.fromElement(demoElem);
// Capture video stream from user's webcam and isolate video track
const stream =
await navigator.mediaDevices.getDisplayMedia(displayMediaOptions);
const [track] = stream.getVideoTracks();
// Restrict video track
await track.restrictTo(restrictionTarget);
// Broadcast restricted stream in <video> element
videoElem.srcObject = stream;
See Using the Element Capture and Region Capture APIs for in-context example code.
Specifications
Specification |
---|
Element Capture # dom-restrictiontarget-fromelement |
Browser compatibility
Report problems with this compatibility data on GitHubdesktop | mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
fromElement() static method |
Legend
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- Full support
- Full support
- In development. Supported in a pre-release version.
- In development. Supported in a pre-release version.
- No support
- No support
- Experimental. Expect behavior to change in the future.