web-h5- 启用摄像头 

<!doctype html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>拍照2</title>
</head>

<body>
    <button id="btnDoCapture">拍照</button>
    <br />
    <video id="camera" style="width: 320px;height: 240px;"></video>
    <canvas id="canvas" style="display:none;"></canvas>
    <br />
    <img src="" id="photo" alt="photo">
    <script>
        !(function () {
            //定义一个全局的变量
            var mediaStreamTrack;
debugger;
            // 老的浏览器可能根本没有实现 mediaDevices，所以我们可以先设置一个空的对象
            if (navigator.mediaDevices === undefined) {
                navigator.mediaDevices = {};
            }
            if (navigator.mediaDevices.getUserMedia === undefined) {
                navigator.mediaDevices.getUserMedia = function (constraints) {
                    // 首先，如果有getUserMedia的话，就获得它
                    var getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;

                    // 一些浏览器根本没实现它 - 那么就返回一个error到promise的reject来保持一个统一的接口
                    if (!getUserMedia) {
                        return Promise.reject(new Error('getUserMedia is not implemented in this browser'));
                    }

                    // 否则，为老的navigator.getUserMedia方法包裹一个Promise
                    return new Promise(function (resolve, reject) {
                        getUserMedia.call(navigator, constraints, resolve, reject);
                    });
                }
            }
            const constraints = {
                video: true,
                audio: false
            };
            let videoPlaying = false;
            let v = document.getElementById('camera');
            let promise = navigator.mediaDevices.getUserMedia(constraints);
            promise.then(stream => {
                // 旧的浏览器可能没有srcObject
                if ("srcObject" in v) {
                    v.srcObject = stream;
                } else {
                    // 防止再新的浏览器里使用它，应为它已经不再支持了
                    v.src = window.URL.createObjectURL(stream);
                }
                v.onloadedmetadata = function (e) {
                    v.play();
                    videoPlaying = true;
                    //用于关闭摄像头用
                    mediaStreamTrack = typeof stream.stop === 'undefined' ? stream : stream.getTracks()[1];
                                
                };
            }).catch(err => {
                console.error(err.name + ": " + err.message);
            })
            document.getElementById('btnDoCapture').addEventListener('click', function () {
                if (videoPlaying) {
                    let canvas = document.getElementById('canvas');
                    
                    canvas.width = v.videoWidth;
                    canvas.height = v.videoHeight;
                    canvas.getContext('2d').drawImage(v, 0, 0);
                    
                    console.log(v);
                    
                    //拍完照关闭
                    mediaStreamTrack && mediaStreamTrack.getTracks()[0].stop();        
                    
                    let data = canvas.toDataURL('image/webp');
                    document.getElementById('photo').setAttribute('src', data);
                }
            }, false);
        })();
    </script>
</body>

</html>

 

posted @ 2020-11-12 12:02  春夏秋冬的千山万水  阅读(222)  评论(0)    收藏  举报