本篇文章给大家分享的是有关怎么在html5中调用摄像头，小编觉得挺实用的，因此分享给大家学习，希望大家阅读完这篇文章后可以有所收获，话不多说，跟着小编一起来看看吧。
调用摄像头
第一种方法navigator.getUserMedia用法详见mdn ，代码如下：
<!doctype html><html lang="en"><head> <meta charset="UTF-8"> <title>摄像头调用1</title></head><body> <video id="v"></video> <script> !(function () { function userMedia() { return navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia || null; } if (userMedia()) { var constraints = { video: true, audio: false }; var media = navigator.getUserMedia(constraints, function (stream) { var v = document.getElementById('v'); var url = window.URL || window.webkitURL; v.src = url ? url.createObjectURL(stream) : stream; v.play(); }, function (error) { console.log("ERROR"); console.log(error); }); } else { console.log("不支持"); } })(); </script></body></html>第二种方法navigator.mediaDevices.getUserMedia用法详见mdn。navigator.mediaDevices.getUserMedia 其实和第一种差不多，主要第二种返回是一个 Promise 对象，代码如下：
<!doctype html><html lang="en"><head> <meta charset="UTF-8"> <title>摄像头调用2</title></head><body> <video id="v"></video> <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 promise = navigator.mediaDevices.getUserMedia(constraints); promise.then(stream => { let v = document.getElementById('v'); // 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(); }; }).catch(err => { console.error(err.name + ": " + err.message); }) })(); </script></body></html>拍照
思路是设置一个标志变量 videoPlaying 看看是否 video 有在 play，监听拍照按钮的点击事件，如果videoPlaying 为 true ，使用一个canvas 获取 video 的宽高（默认 canvas 是不显示的），然后使用 canvas 的drawImage,然后使用 canvas 的 toDataURL返回一个 data url，将这个 url，设置在一个 img 标签上即可?
第一种方法navigator.getUserMedia实现代码：
<!doctype html><html lang="en"><head> <meta charset="UTF-8"> <title>拍照1</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://placehold.it/640&text=Your%20image%20here%20..." id="photo" alt="photo"> <script> !(function () { function userMedia() { return navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia || null; } if (userMedia()) { let videoPlaying = false; let constraints = { video: true, audio: false }; let video = document.getElementById('v'); let media = navigator.getUserMedia(constraints, function (stream) { let url = window.URL || window.webkitURL; video.src = url ? url.createObjectURL(stream) : stream; video.play(); videoPlaying = true; }, function (error) { console.log("ERROR"); console.log(error); }); document.getElementById('take').addEventListener('click', function () { if (videoPlaying) { let canvas = document.getElementById('canvas'); canvas.width = video.videoWidth; canvas.height = video.videoHeight; canvas.getContext('2d').drawImage(video, 0, 0); let data = canvas.toDataURL('image/webp'); document.getElementById('photo').setAttribute('src', data); } }, false); } else { console.log("不支持"); } })(); </script></body></html>第二种navigator.mediaDevices.getUserMedia实现方法:
<!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://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>以上就是怎么在html5中调用摄像头，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注编程网行业资讯频道。
