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 an interface for capturing images from a photographic device referenced through a valid MediaStreamTrack
.
Constructor
ImageCapture.ImageCapture()
- Creates a new
ImageCapture
object.
Properties
ImageCapture.track
Read only- Returns a reference to the
MediaStreamTrack
passed to the constructor.
Methods
ImageCapture.takePhoto()
- Takes a single exposure using the video capture device sourcing a
MediaStreamTrack
and returns aPromise
that resolves with aBlob
containing the data. ImageCapture.getPhotoCapabilities()
- Returns a
Promise
that resolves with aPhotoCapabilities
object containing the ranges of available configuration options. ImageCapture.getPhotoSettings()
- Returns a
Promise
that resolves with aPhotoSettings
object containing the current photo configuration settings. ImageCapture.grabFrame()
- Takes a snapshot of the live video in a
MediaStreamTrack
, returning an ImageBitmap, 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.
var 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.log(error));
}
function onGrabFrameButtonClick() {
imageCapture.grabFrame()
.then(imageBitmap => {
const canvas = document.querySelector('#grabFrameCanvas');
drawCanvas(canvas, imageBitmap);
})
.catch(error => console.log(error));
}
function onTakePhotoButtonClick() {
imageCapture.takePhoto()
.then(blob => createImageBitmap(blob))
.then(imageBitmap => {
const canvas = document.querySelector('#takePhotoCanvas');
drawCanvas(canvas, imageBitmap);
})
.catch(error => console.log(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', function() {
document.querySelector('#grabFrameButton').disabled = false;
document.querySelector('#takePhotoButton').disabled = false;
});
Specifications
Specification | Status | Comment |
---|---|---|
MediaStream Image Capture The definition of 'ImageCapture' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 59 | ? | ? | 46 | ? |
getPhotoSettings() | 61 | ? | ? | 48 | ? |
Feature | Android Webview | Chrome for Android | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | 59 | 59 | ? | ? | ? | 46 | ? |
getPhotoSettings() | 61 | 61 | ? | ? | ? | 48 | ? |