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I want to make a program on the web which will capture an image via the user's webcam.
I am using the getUserMedia Web API. Here is my code, but it does not work. How can I change it to capture the webcam image?
<div id="container">
<video autoplay="true" id="videoElement">
</video>
</div>
<script>
</script>
There is the JS:
var video = document.querySelector("#videoElement");
navigator.getUserMedia, elem = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia || navigator.oGetUserMedia;
console.log(navigator.getUserMedia);
if (navigator.getUserMedia) {
navigator.getUserMedia({video: true}, handleVideo, videoError);
}
function handleVideo(stream) {
video.src = window.URL.createObjectURL(stream);
}
function videoError(e) {
// do something
}
892
You can use this working sample
<!DOCTYPE html>
<html>
<head>
</head>
<body onload="init();">
<h1>Take a snapshot of the current video stream</h1>
Click on the Start WebCam button.
<p>
<button onclick="startWebcam();">Start WebCam</button>
<button onclick="stopWebcam();">Stop WebCam</button>
<button onclick="snapshot();">Take Snapshot</button>
</p>
<video onclick="snapshot(this);" width=400 height=400 id="video" controls autoplay></video>
<p>
Screenshots : <p>
<canvas id="myCanvas" width="400" height="350"></canvas>
</body>
<script>
//--------------------
// GET USER MEDIA CODE
//--------------------
navigator.getUserMedia = ( navigator.getUserMedia ||
navigator.webkitGetUserMedia ||
navigator.mozGetUserMedia ||
navigator.msGetUserMedia);
var video;
var webcamStream;
function startWebcam() {
if (navigator.getUserMedia) {
navigator.getUserMedia (
// constraints
{
video: true,
audio: false
},
// successCallback
function(localMediaStream) {
video = document.querySelector('video');
video.srcObject=localMediaStream;
webcamStream = localMediaStream;
},
// errorCallback
function(err) {
console.log("The following error occured: " + err);
}
);
} else {
console.log("getUserMedia not supported");
}
}
function stopWebcam() {
webcamStream.stop();
}
//---------------------
// TAKE A SNAPSHOT CODE
//---------------------
var canvas, ctx;
function init() {
// Get the canvas and obtain a context for
// drawing in it
canvas = document.getElementById("myCanvas");
ctx = canvas.getContext('2d');
}
function snapshot() {
// Draws current image from the video element into the canvas
ctx.drawImage(video, 0,0, canvas.width, canvas.height);
}
</script>
</html>
There have been updates to the getUserMedia api that now expose takePhoto and grabFrame. The grabFramemethod is less exciting because it does what we have been doing all along and just returning the next video frame from the stream but takePhoto interupts the stream to use the cameras "highest available photographic camera resolution" to capture a compressed image blob. More details here: google devs
var stream, imageCapture;
function getMediaStream()
{
window.navigator.mediaDevices.getUserMedia({video: true})
.then(function(mediaStream)
{
stream = mediaStream;
let mediaStreamTrack = mediaStream.getVideoTracks()[0];
imageCapture = new ImageCapture(mediaStreamTrack);
console.log(imageCapture);
})
.catch(error);
}
function error(error)
{
console.error('error:', error);
}
function takePhoto(img)
{
const img = img || document.querySelector('img');
imageCapture.takePhoto()
.then(blob => {
let url = window.URL.createObjectURL(blob);
img.src = url;
window.URL.revokeObjectURL(url);
})
.catch(error);
};
/* just call */
getMediaStream();
/* and when you want to capture an image */
takePhoto();
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