备份留着万一用到，转自：https://cloud.tencent.com/developer/article/1357730?from=15425
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title></title>
<style type="text/css">
</style>
</head>
<body>
<div>
<b>调用移动端摄像头</b><br>
<label>照相机： <input type="file" id='image' accept="image/*" capture='camera'></label>
<label>摄像机： <input type="file" id='video' accept="video/*" capture='camcorder'></label>
</div>
<hr>
<div class="box1">
<div>
<button onclick="getMedia()">开启摄像头</button>
<video id="video" width="600" height="400" autoplay="autoplay"></video>
</div>
<div>
<button onclick="takePhoto()">拍照</button>
<canvas id="canvas" width="600" height="400"></canvas>
</div>
</div>
</body>
</html>
<script type="text/javascript">
function getMedia() {
let constraints = {
video: {
width: 600,
height: 400
},
audio: true
};
//获得video摄像头区域
let video = document.getElementById("video");
// 这里介绍新的方法，返回一个 Promise对象
// 这个Promise对象返回成功后的回调函数带一个 MediaStream 对象作为其参数
// then()是Promise对象里的方法
// then()方法是异步执行，当then()前的方法执行完后再执行then()内部的程序
// 避免数据没有获取到
let promise = navigator.mediaDevices.getUserMedia(constraints);
// 成功调用
promise.then(function (MediaStream) {
/* 使用这个MediaStream */
video.srcObject = MediaStream;
video.play();
console.log(MediaStream); // 对象
})
// 失败调用
promise.catch(function (err) {
/* 处理error */
console.log(err); // 拒签
});
}
function takePhoto() {
//获得Canvas对象
let video = document.getElementById("video");
let canvas = document.getElementById("canvas");
let ctx = canvas.getContext('2d');
ctx.drawImage(video, 0, 0, 600, 400);
}
</script>
标签：function,摄像,canvas,js,let,video,摄像头,MediaStream From： https://www.cnblogs.com/yyy251/p/17856917.html