CropTarget: 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 CropTarget interface returns a CropTarget instance that can be used to crop a captured video track to the area in which a specified element is rendered.

Because the Region Capture API crops to an area of the current browser tab rather than capturing a specific element, any content drawn on top of the cropped area will be shown in the capture.

Syntax

js
CropTarget.fromElement(element)

Parameters

element

A reference to an Element that you want to use as a crop target. For an element to be used as a crop target, it must be:

  • On-screen
  • Visible, that is, not hidden via display: none for example.

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 via Window.postMessage(), for example).

Return value

A Promise that resolves to a CropTarget object instance, which can then be passed to BrowserCaptureMediaStreamTrack.CropTo() to crop the video captured in the track to just the area the specified DOM element is rendered in.

CropTarget objects are serializable. They can be passed to another document using mechanisms such as Window.postMessage().

Examples

js
// Options for getDisplayMedia()
const displayMediaOptions = {
  preferCurrentTab: true,
};

// Create crop target from DOM element
const demoElem = document.querySelector("#demo");
const cropTarget = await CropTarget.fromElement(demoElem);

// Capture video stream from user's webcam and isolate video track
const stream =
  await navigator.mediaDevices.getDisplayMedia(displayMediaOptions);
const [track] = stream.getVideoTracks();

// Crop video track
await track.cropTo(cropTarget);

// Broadcast cropped stream in <video> element
videoElem.srcObject = stream;

See Using the Element Capture and Region Capture APIs for in-context example code.

Specifications

Specification
Region Capture
# dom-croptarget-fromelement

Browser compatibility

BCD tables only load in the browser

See also