html5挪用攝像頭功用

2023年3月7日 142次阅读来源: Moorez

媒介

前些天，線上筆試的時刻，發明須要瀏覽器贊同開啟攝像頭，覺得像是 js 挪用的，因為當時筆試，也就沒想到這麼多🤣。本日閑來無事，看了下本身的 todo，發明有這個挪用攝像頭的todo，才想到😂。網上查了一下，果真 js 有挪用攝像頭的 api，為此本身寫一個 demo ，防備遺忘。

正文

挪用攝像頭

一共有兩種完成體式格局，一種是運用navigator.getUserMedia（該特徵已從 Web 規範中刪除，雖然一些瀏覽器現在依然支撐它，但或許會在將來的某個時候住手支撐，請只管不要運用該特徵），前面一種已從 Web 規範中刪除，僅為了向後兼容而存在，第二種是運用navigator.mediaDevices.getUserMedia(引薦運用),這兩種要領 Safari 貌似都不支撐。。。。

第一種要領navigator.getUserMedia用法詳見 mdn ，代碼以下：

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

<head>
    <meta charset="UTF-8">
    <title>攝像頭挪用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("不支撐");
            }
        })();
    </script>
</body>
</html>

第二種要領navigator.mediaDevices.getUserMedia用法詳見mdn。navigator.mediaDevices.getUserMedia 實在和第一種差不多，重要第二種返回是一個 Promise 對象，代碼以下：

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

<head>
    <meta charset="UTF-8">
    <title>攝像頭挪用2</title>
</head>

<body>
    <video id="v"></video>
    <script>
        !(function () {
            // 老的瀏覽器能夠基礎沒有完成 mediaDevices，所以我們能夠先設置一個空的對象
            if (navigator.mediaDevices === undefined) {
                navigator.mediaDevices = {};
            }
            if (navigator.mediaDevices.getUserMedia === undefined) {
                navigator.mediaDevices.getUserMedia = function (constraints) {
                    // 起首，假如有getUserMedia的話，就取得它
                    var getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;

                    // 一些瀏覽器基礎沒完成它 - 那末就返回一個error到promise的reject來堅持一個一致的接口
                    if (!getUserMedia) {
                        return Promise.reject(new Error('getUserMedia is not implemented in this browser'));
                    }

                    // 不然，為老的navigator.getUserMedia要領包裹一個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');
                // 舊的瀏覽器能夠沒有srcObject
                if ("srcObject" in v) {
                    v.srcObject = stream;
                } else {
                    // 防備再新的瀏覽器里運用它，應為它已不再支撐了
                    v.src = window.URL.createObjectURL(stream);
                }
                v.onloadedmetadata = function (e) {
                    v.play();
                };
            }).catch(err => {
                console.error(err.name + ": " + err.message);
            })
        })();
    </script>
</body>
</html>

照相

思緒是設置一個標誌變量 videoPlaying 看看是不是 video 有在 play，監聽照相按鈕的點擊事宜，假如videoPlaying 為 true ，運用一個canvas 獵取 video 的寬高（默許 canvas 是不顯現的），然後運用 canvas 的drawImage,然後運用 canvas 的 toDataURL返回一個 data url，將這個 url，設置在一個 img 標籤上即可😀

第一種要領navigator.getUserMedia完成代碼：

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>照相1</title>
</head>
<body>
    <button id="take">照相</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("不支撐");
            }
        })();
    </script>
</body>
</html>

第二種navigator.mediaDevices.getUserMedia完成要領:

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

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

<body>
    <button id="take">照相</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 () {
            // 老的瀏覽器能夠基礎沒有完成 mediaDevices，所以我們能夠先設置一個空的對象
            if (navigator.mediaDevices === undefined) {
                navigator.mediaDevices = {};
            }
            if (navigator.mediaDevices.getUserMedia === undefined) {
                navigator.mediaDevices.getUserMedia = function (constraints) {
                    // 起首，假如有getUserMedia的話，就取得它
                    var getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;

                    // 一些瀏覽器基礎沒完成它 - 那末就返回一個error到promise的reject來堅持一個一致的接口
                    if (!getUserMedia) {
                        return Promise.reject(new Error('getUserMedia is not implemented in this browser'));
                    }

                    // 不然，為老的navigator.getUserMedia要領包裹一個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 => {
                // 舊的瀏覽器能夠沒有srcObject
                if ("srcObject" in v) {
                    v.srcObject = stream;
                } else {
                    // 防備再新的瀏覽器里運用它，應為它已不再支撐了
                    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>

    原文作者：Moorez
    原文地址: https://segmentfault.com/a/1190000014741852
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。