BrowserCaptureMediaStreamTrack: cropTo() 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 cropTo() method of the BrowserCaptureMediaStreamTrack interface crops a self-capture stream to the area in which a specified DOM element is rendered.

Syntax

js
cropTo(cropTarget)

Parameters

cropTarget

A CropTarget instance representing the element rendering area the stream should be cropped to, or null/undefined, in which case any previously-set cropping is removed from the track.

Return value

A Promise that resolves to undefined.

The promise will reject if:

  • The track kind is not "video", or its readyState is not "live".
  • The crop target element no longer exists.
  • The track being cropped is not a track captured from the user's screen.
  • cropTarget is not a CropTarget instance, null, or undefined.
  • cropTarget was created in a tab other than the one being captured.

Note: In Chromium, if a track has clones, cropTo() will reject (see Chrome issue 41482026).

Examples

Basic cropping example

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.

Stopping the cropping

You can stop the cropping by making a call to cropTo() on a previously-cropped track, passing an argument of null to it:

js
// Stop cropping
await track.cropTo(null);

Specifications

Specification
Region Capture
# dom-browsercapturemediastreamtrack-cropto

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
cropTo
Experimental

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.

See also