html5调用摄像头功能的实现代码(3)

发布时间：2020-05-12 02:17 所属栏目：115 来源：站长网

导读：!doctype htmlhtml lang=enheadmeta charset=UTF-8title拍照2/title/headbodybutton id=take拍照/buttonbr /video id=v style=width: 640px;height: 480px;/videocanvas id=canvas style=display:none;/canvasbr /i

<!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <title>拍照2</title> </head> <body> <button id="take">拍照</button> <br /> <video id="v" style="width: 640px;height: 480px;"></video> <canvas id="canvas" style="display:none;"></canvas> <br /> <img src=http://www.jb51.net/html5/"http:/placehold.it/640&text=Your%20image%20here%20..." id="photo" alt="photo"> <script> !(function () { // 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('v'); 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; }; }).catch(err => { console.error(err.name + ": " + err.message); }) document.getElementById('take').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); let data = canvas.toDataURL('image/webp'); document.getElementById('photo').setAttribute('src', data); } }, false); })(); </script> </body> </html>

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