JS调用安卓手机摄像头扫描二维码

来源：jb51　　时间：2018/10/17 8:45:26　　对本文有异议

项目要求：

使用H5模仿微信扫一扫付款功能

经过一系列的查找最后发现可以使用 JS调用手机摄像头然后用画布把当前摄像头的数据转成Base64的png图片，经过QrCode直接再本地识别。

优点：

兼容大多数浏览器

本地识别不占用服务端资源

代码比较简单只有一个页面

<html lang="ZH-CN">
<head>
 <meta charset="utf-8">
 <title>Web QrCode Test</title>
<script type="text/javascript" src="jquery-1.8.3.min.js"></script>
 
<script type="text/javascript" src="jsqrcode/src/grid.js"></script>
<script type="text/javascript" src="jsqrcode/src/version.js"></script>
<script type="text/javascript" src="jsqrcode/src/detector.js"></script>
<script type="text/javascript" src="jsqrcode/src/formatinf.js"></script>
<script type="text/javascript" src="jsqrcode/src/errorlevel.js"></script>
<script type="text/javascript" src="jsqrcode/src/bitmat.js"></script>
<script type="text/javascript" src="jsqrcode/src/datablock.js"></script>
<script type="text/javascript" src="jsqrcode/src/bmparser.js"></script>
<script type="text/javascript" src="jsqrcode/src/datamask.js"></script>
<script type="text/javascript" src="jsqrcode/src/rsdecoder.js"></script>
<script type="text/javascript" src="jsqrcode/src/gf256poly.js"></script>
<script type="text/javascript" src="jsqrcode/src/gf256.js"></script>
<script type="text/javascript" src="jsqrcode/src/decoder.js"></script>
<script type="text/javascript" src="jsqrcode/src/qrcode.js"></script>
<script type="text/javascript" src="jsqrcode/src/findpat.js"></script>
<script type="text/javascript" src="jsqrcode/src/alignpat.js"></script>
<script type="text/javascript" src="jsqrcode/src/databr.js"></script>
</head>
<body>
 <div class="booth">
 <video id="video" width="400" height="400"></video>
 <canvas id='canvas' width='400' height='400'></canvas>
 <img id='img' src=''>
 </div>
 
 <div id="mmm"></div>
 
 <canvas id="qr-canvas" width="640" height="480"></canvas>
<script>
 
 
 //初始化媒体对象
 var c=0;
 var video = document.getElementById('video'),
  canvas = document.getElementById('canvas'),
  img = document.getElementById('img'),
  vendorUrl = window.URL || window.webkitURL;
  
 //媒体对象
 navigator.getMedia = navigator.getUserMedia ||
       navagator.webkitGetUserMedia ||
       navigator.mozGetUserMedia ||
       navigator.msGetUserMedia;
 navigator.getMedia({
  video: true, //使用摄像头对象
  audio: false //不适用音频
 }, function(strem){
  console.log(strem);
  video.src = vendorUrl.createObjectURL(strem);
  video.play();
 }, function(error) {
  //error.code
  console.log(error);
 });
 
 //启动定时器
 setTimeout("actionP(null)","1000");
 
 //定时器
 function actionP(data){
  if(data==null){
  Screenshot()
   
  }else{
  if(data!=null & data!="error decoding QR Code"){//识别出数据
   if(data.indexOf("http")!=-1){
   window.location.href=data;
   }else alert(data);
   
   }else{//没有数据循环十次
    c++;
    if(c<10){
     setTimeout("actionP(null)","1000");
    }
    
   }
  }
  
 }
 
 
 function Screenshot(){//截取图像
 canvas.getContext('2d').drawImage(video, 0, 0, 400, 400);
 var imgData = canvas.toDataURL("image/png");
 load(imgData);
 img.src=imgData;
  
 }
 ////////////////////////////////////////识别二维码////////////////////////////////////////////
 
 function dragenter(e) {
 e.stopPropagation();
 e.preventDefault();
 }
 
 function dragover(e) {
 e.stopPropagation();
 e.preventDefault();
 }
 function drop(e) {
 e.stopPropagation();
 e.preventDefault();
 
 var dt = e.dataTransfer;
 var files = dt.files;
 
 
 }
 
 
 function load(name)
 {
 initCanvas(640,480);
 //识别二维码并回调方法
 qrcode.callback = actionP;
 qrcode.decode(name);
 }
 
 function initCanvas(ww,hh)//创建画板
 {
 gCanvas = document.getElementById("qr-canvas");
 gCanvas.addEventListener("dragenter", dragenter, false); 
 gCanvas.addEventListener("dragover", dragover, false); 
 gCanvas.addEventListener("drop", drop, false);
 var w = ww;
 var h = hh;
 gCanvas.style.width = w + "px";
 gCanvas.style.height = h + "px";
 gCanvas.width = w;
 gCanvas.height = h;
 gCtx = gCanvas.getContext("2d");
 gCtx.clearRect(0, 0, w, h);
 imageData = gCtx.getImageData( 0,0,320,240);
 }
 
 
 </script>
</body>
</html>