网页制作 发布日期:2024/12/29 浏览次数:1
navigator.mediaDevices.getUserMedia
应项目要求,需要实现移动端app嵌入H5页面完成实人认证的功能。打开getUserMedia文档,链接如下:
https://developer.mozilla.org/zh-CN/docs/Web/API/MediaDevices/getUserMedia
看上去很简单,最终却写的怀疑人生。
API环境
问题一:(为什么不管怎么配置都显示前置摄像头)
想正常使用API必须在https环境下进行,否则你会发现不管怎么写,都只能调用默认的摄像头(大部分都是前置,只有少部分是后置)
前端开发者可以将文件上传至"码云"仓库,获取https链接然后在手机上预览
链接:码云仓库入口
问题二:(API在安卓和ios效果一样吗?)
根据官方文档,目前navigator.mediaDevices.getUserMedia在ios上只支持11版本以上,且只能在safari正常运行。安卓目前没有发现版本限制,需要兼容的代码如下
if (navigator.mediaDevices === undefined) { navigator.mediaDevices = {}; } if (navigator.mediaDevices.getUserMedia === undefined) { navigator.mediaDevices.getUserMedia = function (constraints) { var getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia || navigator.oGetUserMedia; if (!getUserMedia) { return Promise.reject(new Error('getUserMedia is not implemented in this browser')); } return new Promise(function (resolve, reject) { getUserMedia.call(navigator, constraints, resolve, reject); }); } }
问题三:(第一次启用成功调用前置摄像头,第二次需要调用后置却黑屏或者失败)
失败的原因很多,列举两个一开始我遇到的问题
1.前置摄像头调用后,摄像功能需要关闭后才能正常执行第二次调用,否则会报错:设备被占用。解决方法,在每次执行调用方法前,先关闭摄像设备。
if (window.stream) { window.stream.getTracks().forEach(track => { track.stop(); }); }
亲测有用,别的找了很多停止的方法都没有效果。
2.调用后置API的方法还是无法唤醒后置摄像头,于是我找到另外一个方法,通过查看手机摄像头ID,来直接唤醒后置。
var deviceInfoId="", //摄像头ID num = 0, //摄像头数量 carema = []; //摄像头ID数组 //在页面加载完成后获得设备ID数组 window.onload = navigator.mediaDevices.enumerateDevices().then(gotDevices); function gotDevices(deviceInfos) { for (let i = 0; i < deviceInfos.length; ++i) { if (deviceInfos[i].kind === 'videoinput') { carema.push(deviceInfos[i].deviceId) } } deviceInfoId = carema[后置位置]; } var constraints = { audio: false, video: { deviceId: deviceInfoId, //放在app里面需要下面配置一下 "permissions": { "audio-capture": { "description": "Required to capture audio using getUserMedia()" }, "video-capture": { "description": "Required to capture video using getUserMedia()" } } } }; navigator.mediaDevices.getUserMedia(constraints) .then(function (stream) { var video = document.getElementById('video'); try { window.stream = stream; video.srcObject = stream; } catch (error) { video.src = window.URL.createObjectURL(stream); } this.localMediaStream = stream; // video.play(); 这个加不加好像没有影响 }) .catch(function (err) { console.log(err.name + ": " + err.message); });
如果只是一部手机可以这样,但是测试了多部手机发现摄像头数组毫无规律可循,这个方法慎用。
如果页面上添加选择摄像设备的按钮的话,这个方法还是不错的。查看设备能调用几个摄像头链接如下:https://webrtc.github.io/samples/src/content/devices/input-output/
由于我们的项目页面不希望出现切换按钮,面对后置出现的众多BUG,最终选择放弃,使用input调用摄像头。
<input class="card_input" v-on:change="appCapture($event)" type="file" accept="image/*" capture="camera" />
成功调用后用canvas实现成像并适应屏幕大小
我这里的代码是取video的宽高然后复制给canvas,这样可以让canvas和video保持一致,只用给video设置宽度100%,高度调节成合适的值,就实现了适应手机屏幕。
var video = document.getElementById('video'); var canvas = document.getElementById('canvas'), ctx = canvas.getContext('2d'), CHeight = video.clientHeight, //获取屏幕大小让canvas自适应 CWidth = video.clientWidth; canvas.width = CWidth; canvas.height = CHeight; //localMediaStream 在data里定义一个{} if (localMediaStream) { ctx.drawImage(video, 0, 0, CWidth, CHeight); var dataURL = canvas.toDataURL('image/jpeg'); //dataURL = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAA' img.src = dataURL;
video成像镜像问题
API唤醒的前置摄像头是相反的,很不舒服很不舒服。
之后用css处理一下给video添加 transform: rotate(180deg),可以实现反转,但是还是没有达到和手机一样的效果。
这时候可以选择通过设备ID调用前置摄像头,前置摄像头的laval一直都是“default”,也有的是空值,但是也能实现。
配置代码如下:
var constraints = window.constraints = { audio: false, video: { sourceId: 'default', facingMode: { exact: "user" } } };
完美调用自己手机的前置摄像头!!!
完整代码如下:
页面代码:
<div @click='moveToCameraAVG()' v-cloak> <img v-if="imginfo!==''" :src="imginfo" /> <div class="warm_title2">点击自拍一张头像</div> </div> <video id="video" class="pic_video" playsinline autoplay x5-video-player-type="h5" style='object-fit:fill'></video> <canvas id="canvas" class="canvas_pic" style='margin: 0;padding: 0;'></canvas> <div class="bottom_div"> <div>拍照</div> <img src='images/pic_btn.png' class="capture-btn" @click='captureAvg' /> </div>
// 头像相机 moveToCameraAVG() { var self = this; if (navigator.mediaDevices === undefined) { navigator.mediaDevices = {}; } if (navigator.mediaDevices.getUserMedia === undefined) { navigator.mediaDevices.getUserMedia = function (constraints) { var getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia || navigator.oGetUserMedia; if (!getUserMedia) { return Promise.reject(new Error('getUserMedia is not implemented in this browser')); } return new Promise(function (resolve, reject) { getUserMedia.call(navigator, constraints, resolve, reject); }); } } if (window.stream) { window.stream.getTracks().forEach(track => { track.stop(); }); } var constraints = window.constraints = { audio: false, video: { sourceId: 'default', facingMode: { exact: "user" } } }; navigator.mediaDevices.getUserMedia(constraints) .then(function (stream) { var video = document.getElementById('video'); try { window.stream = stream; video.srcObject = stream; } catch (error) { video.src = window.URL.createObjectURL(stream); } self.localMediaStream = stream; video.play(); }) .catch(function (err) { alert(err.name + ": " + err.message); }); }, //停止摄像机 stopCapture: function () { var video = document.getElementById('video'); if (!video.srcObject) return let stream = video.srcObject let tracks = stream.getTracks(); tracks.forEach(track => { track.stop() }) }, // 头像照片 captureAvg() { var vm = this; var video = document.getElementById('video'); var canvas = document.getElementById('canvas'), ctx = canvas.getContext('2d'), CHeight = video.clientHeight, //获取屏幕大小让canvas自适应 CWidth = video.clientWidth; canvas.width = CWidth; canvas.height = CHeight; if (vm.localMediaStream) { ctx.drawImage(video, 0, 0, CWidth, CHeight); var dataURL = canvas.toDataURL('image/jpeg'); //dataURL = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAA' vm.imginfo = dataURL; // 停止摄像机 video.pause(); this.stopCapture(); } },