html调用摄像头，并拍照下载

调用摄像头 https://developer.mozilla.org/zh-CN/docs/Web/API/MediaDevices/getUserMedia

<video id="video" width="1200" height="880" autoplay ></video>
<canvas id="canvas" width="1500" height="1100" style="display:none;"></canvas>

window.onload = function() {
			let video = document.getElementById("video")
			let videoObj = { video: { width: 1500, height: 1100 } }
			let errBack = function(error) {
				console.log(error.message);
				console.log("Video capture error: ", error.message+" " +error.code); 
			}
			navigator.mediaDevices.getUserMedia(videoObj).then(function(stream) {
				video.srcObject = stream
				video.play()
			}).catch(function(err){
				errBack(err)
			})
		}

拍照功能，实际是通过canvas获取，然后下载

<button onclick="catchPhoto()" style="border: none; border: 1px solid #1DA57A; padding: