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。更多详情敬请关注亿速云行业资讯频道。
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