ImageCapture
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The ImageCapture
interface of the MediaStream Image Capture API provides methods to enable the capture of images or photos from a camera or other photographic device. It provides an interface for capturing images from a photographic device referenced through a valid MediaStreamTrack
.
Constructor
ImageCapture()
Experimental-
Creates a new
ImageCapture
object which can be used to capture still frames (photos) from a givenMediaStreamTrack
which represents a video stream.
Instance properties
ImageCapture.track
Read only Experimental-
Returns a reference to the
MediaStreamTrack
passed to the constructor.
Instance methods
The ImageCapture
interface is based on EventTarget
, so it includes the methods defined by that interface as well as the ones listed below.
ImageCapture.takePhoto()
Experimental-
Takes a single exposure using the video capture device sourcing a
MediaStreamTrack
and returns aPromise
that resolves with aBlob
containing the data. ImageCapture.getPhotoCapabilities()
Experimental-
Returns a
Promise
that resolves with aPhotoCapabilities
object containing the ranges of available configuration options. ImageCapture.getPhotoSettings()
Experimental-
Returns a
Promise
that resolves with aPhotoSettings
object containing the current photo configuration settings. ImageCapture.grabFrame()
Experimental-
Takes a snapshot of the live video in a
MediaStreamTrack
, returning anImageBitmap
, if successful.
Example
The following code is taken from Chrome's Grab Frame - Take Photo Sample. Since ImageCapture
requires some place to capture an image from, the example below starts with a device's media device (in other words a camera).
This example shows, roughly, a MediaStreamTrack
extracted from a device's MediaStream
. The track is then used to create an ImageCapture
object so that takePhoto()
and grabFrame()
can be called. Finally, it shows how to apply the results of these calls to a canvas object.
js
let imageCapture;
function onGetUserMediaButtonClick() {
navigator.mediaDevices
.getUserMedia({ video: true })
.then((mediaStream) => {
document.querySelector("video").srcObject = mediaStream;
const track = mediaStream.getVideoTracks()[0];
imageCapture = new ImageCapture(track);
})
.catch((error) => console.error(error));
}
function onGrabFrameButtonClick() {
imageCapture
.grabFrame()
.then((imageBitmap) => {
const canvas = document.querySelector("#grabFrameCanvas");
drawCanvas(canvas, imageBitmap);
})
.catch((error) => console.error(error));
}
function onTakePhotoButtonClick() {
imageCapture
.takePhoto()
.then((blob) => createImageBitmap(blob))
.then((imageBitmap) => {
const canvas = document.querySelector("#takePhotoCanvas");
drawCanvas(canvas, imageBitmap);
})
.catch((error) => console.error(error));
}
/* Utils */
function drawCanvas(canvas, img) {
canvas.width = getComputedStyle(canvas).width.split("px")[0];
canvas.height = getComputedStyle(canvas).height.split("px")[0];
let ratio = Math.min(canvas.width / img.width, canvas.height / img.height);
let x = (canvas.width - img.width * ratio) / 2;
let y = (canvas.height - img.height * ratio) / 2;
canvas.getContext("2d").clearRect(0, 0, canvas.width, canvas.height);
canvas
.getContext("2d")
.drawImage(
img,
0,
0,
img.width,
img.height,
x,
y,
img.width * ratio,
img.height * ratio
);
}
document.querySelector("video").addEventListener("play", () => {
document.querySelector("#grabFrameButton").disabled = false;
document.querySelector("#takePhotoButton").disabled = false;
});
Specifications
Specification |
---|
MediaStream Image Capture # imagecaptureapi |
Browser compatibility
BCD tables only load in the browser