HTML5调用手机前置摄像头或后置摄像头拍照，canvas显示,通过Android测试

时间 2019-11-07

标签 html5 html 调用手机前置摄像头后置拍照 canvas 显示通过 android 测试栏目 HTML5 繁體版

原文原文链接

HTML5能够经过调用navigator.getUserMedia来获取手机设备摄像头，兼容性写法以下javascript

window.navigator.getUserMedia = navigator.getUserMedia || navigator.webKitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;css

可是navigator.getUserMediau已经从 Web 标准中删除，虽然部分浏览器可使用，生产环境中仍是要作好兼容。新的API更替为MediaDevices.getUserMedia。MediaDevices.getUserMedia能够经过video的facingMode属性指定调用手机的前置或后置摄像头
video:{ 'facingMode': "user" }//调用前置摄像头
video: { facingMode: { exact: "environment" } }//后置html

具体代码：java

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0,maximum-scale=1.0,minimum-scale=1.0,user-scalable=no">
    <title>Document1</title>
    <style type='text/css'>
        * { margin: 0; padding: 0; }

        html, body { height: 100%; }

        .flex { display: flex; }

        .flex-row { flex-direction: row; justify-content: space-around; align-items: center; }

        .flex-column { flex-direction: column; justify-content: flex-start; align-items: center; }

        body { overflow: auto; background: #fff; }

        .title { width: 920px; padding: 30px; align-items: flex-end; }

        .title h1 { padding-bottom: 20px; font-size: 38px; color: #ffffff; text-shadow: 0 1px 3px #222222; }

        .title p { font-size: 18px; color: #f5f5f5; text-shadow: 0 1px 3px #565656; }

        .wrap { width: 1220px; }

        .wrap .reference { position: relative; padding: 10px; background-color: rgba(255, 255, 255, 0); border-radius: 10px; box-shadow: 0 0 20px #a1a19f; }

        .wrap .reference img.face { display: block; width: 320px; height: auto; border-radius: 10px; }

        .wrap .reference img.toggle { position: absolute; right: 10px; top: 10px; width: 50px; height: 50px; }

        .wrap .scan video { background-color: rgba(0, 0, 0, .8); border-radius: 10px; }

        .wrap .control { justify-content: space-around; height: 456px; padding: 0 20px; }

        .wrap .control p { width: 160px; height: 60px; background-color: #f9f9f9; text-align: center; line-height: 60px; color: #ffffff; font-size: 24px; border-radius: 8px; cursor: pointer; box-shadow: -8px -8px 150px -8px #b2b3b5 inset, 0 0 5px #222222; text-shadow: 0 0 1px #222222; transition: .5s; }

        .wrap .control p:hover { box-shadow: -8px -8px 150px -8px #50c4f1 inset, 0 0 5px #ffffff; }

        .wrap .scan { position: relative; overflow: hidden; }

        .wrap .scan .strainer { position: absolute; top: 10px; width: 320px; z-index: 999; height: 3px; }

        .wrap .scan .capture { width: 320px; height: 456px; }

        .wrap .scan .strainer.on { background: linear-gradient(to left, transparent, #0bffb2, transparent); animation: scan 1s linear infinite; }

        @keyframes scan {
            0% { top: 10px; }
            50% { top: 456px; }
            100% { top: 10px; }
        }

    </style>
    <script type="text/javascript" src="vconsole.min.js"></script>
</head>
<body>
    <div class="title flex flex-column">
</div>
<div class="wrap flex flex-row">
    <div class="control flex flex-column">
        <p class="open">开启摄像头</p>
        <p class="recognition">显示到Canvas</p>
        <p class="close">关闭摄像头</p>
    </div>
    <div class="scan reference">
        <div class="strainer"></div>
        <video class="capture" width="320" height="456" src=""></video>
    </div>

</div>

    <script type="text/javascript">
        var buffer;
        var oCapture = document.querySelector(".capture"),
        open = document.querySelector(".open"),
        recognition = document.querySelector(".recognition"),
        close = document.querySelector(".close");
        var control = document.querySelector(".control");

        window.navigator.getUserMedia = navigator.getUserMedia || navigator.webKitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;

        function invokingCarera(){
            if(navigator.mediaDevices&&navigator.mediaDevices.getUserMedia){
                navigator.mediaDevices.getUserMedia({
                    'audio':true,
                    'video':{ 'facingMode': "user" }//调用前置摄像头，后置摄像头使用video: { facingMode: { exact: "environment" } }
                })
                .then(function(mediaStream) {console.log(555);getVideoStream(mediaStream)})
                .catch(function(error) { console.log(666);console.log(error) })
            }else if(navigator.getUserMedia){
                navigator.getUserMedia({
                    'video':true,
                    'audio':true
                },getVideoStream,getFail)
            }else{
                alert('不支持摄像头调用！')
            }
        }
        //调用成功
        function getVideoStream(stream){
            buffer = stream;
            if(oCapture.mozSrcObject !== undefined){
                oCapture.mozSrcObject = buffer;
            }else{
                oCapture.src = window.URL && window.URL.createObjectURL(buffer);                
            }
            oCapture.play();
        }
        function getFail(){

        }
        recognition.onclick = function(){

        }
        control.addEventListener('click',function(e){
            e = e || window.event;
            var className = e.target.className;
            switch(className){
                case 'open':
                invokingCarera();
                break;
                case 'close':
                closeCamera();
                break;
                case 'recognition':
                screenShot();
                break;
                default:
                break;
            }
        })
        function closeCamera(){
            buffer&&buffer.getTracks()[1].stop();//关闭摄像头
        }        
        window.requestAnimFrame = (function(){
          return  window.requestAnimationFrame       ||
                  window.webkitRequestAnimationFrame ||
                  window.mozRequestAnimationFrame    ||
                  function( callback ){
                    window.setTimeout(callback, 1000 / 60);
                  };
        })();
        function screenShot(){
            var canvas = document.createElement('canvas');
            canvas.width=320,canvas.height = 456;
            document.querySelector(".wrap").appendChild(canvas);
            var ctx =  canvas.getContext('2d');
            function drawVideo(){
                ctx.drawImage(oCapture,0,0,320,456);
                ctx.font = "30px sans-serif";
                ctx.fillStyle = "blue";
                ctx.fillText("请眨眼", 50, 50);
                requestAnimationFrame(drawVideo);
            }
            window.requestAnimationFrame(drawVideo);
        }
    </script>
</body>
</html>

以上代码并无进行太多的错误处理，好比用户拒绝受权访问摄像头或浏览器不支持等状况，生产环境使用需添加错误处理代码web

以上代码在PC端和Android手机端和微信测试经过，IOS下浏览器均不支持，听说IOS11会开放权限。
注意，以上HTML须要在HTTPS下访问方可正常工做
查看在线DEMO，若是使用微信访问可能被屏蔽，微信打开连接后点击右下角“访问原网页”
如需本地测试请使用Chrome插件：web-server;
webserver使用方法：chrome://apps > web-server > choose folder 勾选 Show Advanced Settings下Set CORS Headers便可
使用input type=”file”调用摄像头拍照能够参考camera APIchrome

补充下，获取vedio的实际尺寸，能够经过：this.videoWidth，this.videoHeight获取。canvas

HTML5之drawImage函数

可用函数浏览器

drawImage(image, x, y) //按原图片大小绘制。
drawImage(image, x, y, width, height) //按指定大小绘制。
drawImage(image, sourceX, sourceY, sourceWidth, sourceHeight, 
destX, destY, destWidth, destHeight) //经常使用于图片裁剪

参数微信

image:所要绘制的图像。这必须是表示  标记或者屏幕外图像的 Image 对象，或者是 Canvas 元素。 
x和y：图片在文档中的坐标位置。 
width和height：图片的宽高。 
对于drawImage(image, sourceX, sourceY, sourceWidth, sourceHeight, 
destX, destY, destWidth, destHeight) 经常使用有图片的裁剪。其参数含义是原来image上从某一个位置开始(sourceX,sourceY)，指定长宽进行剪切(sourceX,sourceY),而后将剪切的内容放到位置为(destX,destY),宽度为(destWidth),高度为(destHeight)的位置上，固然裁剪后的会覆盖原来的图片。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>drawImage</title>
</head>
<body>
    <canvas id="myCanvas" width="500" height="400"></canvas>
    <script type="text/javascript">
        var canv=document.getElementById("myCanvas");
        var ctx = canv.getContext("2d");
            img = new Image();
            img.src = "2.jpg";
        //当图片加载完毕的时候在drawImage,不然可能图片尚未加载完毕
        //固然画不上去喽，这就和浏览器的性能有关了。
            img.onload=function(){
                ctx.drawImage(img,0,0,500,500);
            //ctx.drawImage(img,0,0,100,100,300,100,100,100);

            }
    </script>
</body>
</html>

除此以外，drawImage()还能够画video，参考连接app