ImageCapture: grabFrame() method

Syntax

js

grabFrame()

Return value

A Promise that resolves to an ImageBitmap object.

Exceptions

InvalidStateError DOMException: Thrown if readyState property of the MediaStreamTrack passing in the constructor is not live.
UnknownError DOMException: Thrown if the operation can't complete for any reason.

This example is extracted from this Simple Image Capture demo. It shows how to use the Promise returned by grabFrame() to copy the returned frame to a <canvas> element. For simplicity it does not show how to instantiate the ImageCapture object.

js

let grabFrameButton = document.querySelector("button#grabFrame");
let canvas = document.querySelector("canvas");

grabFrameButton.onclick = grabFrame;

function grabFrame() {
  imageCapture
    .grabFrame()
    .then((imageBitmap) => {
      console.log("Grabbed frame:", imageBitmap);
      canvas.width = imageBitmap.width;
      canvas.height = imageBitmap.height;
      canvas.getContext("2d").drawImage(imageBitmap, 0, 0);
      canvas.classList.remove("hidden");
    })
    .catch((error) => {
      console.error("grabFrame() error: ", error);
    });
}