function (win, doc) {
	    function QRScan(div_id) {
	        this.div_id = div_id;
	        this.div_can = null;
	        this.videos = [];
	        this.medioConfig = {};
	        this.can_open = false;
	        this.init();
	    }
	
	    QRScan.prototype = {
	        init: function () {
	            win.URL = (win.URL || win.webkitURL || win.mozURL || win.msURL);
	            var promisifiedOldGUM = function(constraints) {
	                var getUserMedia = (navigator.getUserMedia ||
	                    navigator.webkitGetUserMedia || navigator.mozGetUserMedia);
	                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(navigator.mediaDevices === undefined) {
	                navigator.mediaDevices = {};
	            }
	            if(navigator.mediaDevices.getUserMedia === undefined) {
	                navigator.mediaDevices.getUserMedia = promisifiedOldGUM;
	            }
	
	            var self = this;
	            self.div_can = doc.getElementById(self.div_id);
	            navigator.mediaDevices.enumerateDevices().then(function(devices) {
	                devices.forEach(function (dv) {
	                    var kind = dv.kind;
	                    if (kind.match(/^video.*/)) {
	                        self.videos.push(dv.deviceId);
	                        console.log(dv);
	                    }
	                });
	                var len = self.videos.length;
	                self.can_open = true;
	                self.medioConfig = {
	                    audio: false,
	                    video: { deviceId: self.videos[len - 1] }
	                }
	            });
	        },
	        openScan: function () {
	            var self = this;
	            if (self.can_open) {
	                var vd = doc.createElement('video');
	                vd.setAttribute('id', 'video_id');
	                navigator.mediaDevices.getUserMedia(self.medioConfig).then(function (stream) {
	                    vd.src = win.URL.createObjectURL(stream);
	                    self.div_can.appendChild(vd);
	                }).catch(function (err) {
	                    var p = doc.createElement('p');
	                    p.innerHTML = 'ERROR: ' + err.name +
	                                  '<br>该浏览器不支持调用摄像头，请使用夸克浏览器';
	                    self.div_can.appendChild(p);
	                });
	                //vd.play();
	            }
	        },
	
	        closeScan: function () {
	            this.div_can.innerHTML = '';
	        },
	        // 截图上传
	        getImgDecode: function (func) {
	            var self = this;
	            var video = doc.getElementById('video_id');
	            var canvas = doc.createElement('canvas');
	            canvas.width = 340;
	            canvas.height = 305;
	            var ctx = canvas.getContext('2d');
	            ctx.drawImage(video, 0, 0, 340, 305);
	            var scan=this;
	            blob2text(self.Base64ToBlob(canvas.toDataURL())).then(
	
	                function(code){
	                    alert(code.data);
	                    this.closeScan();
	                }
	
	            );
	
	                // alert(qrcode.decode(,1024));
	            // if (canvas.toBlob === undefined) {
	            //     var base64 = canvas.toDataURL();
	            //     var blob = self.Base64ToBlob(base64);
	            //     self.sendBlob(blob, func);
	            // } else {
	            //     canvas.toBlob(function (blob) {
	            //         self.sendBlob(blob, func);
	            //     });
	            // }
	        },
	
	        Base64ToBlob: function (base64) {
	            var code = win.atob(base64.split(',')[1]);
	            var len = code.length;
	            var as = new Uint8Array(len);
	            for (var i = 0; i < len; i++) {
	                as[i] = code.charCodeAt(i);
	            }
	            return new Blob([as], {type: 'image/png'});
	        }
	    }
	
	    win.QRScan = QRScan;
	}(window, document));
	
	
	
	function blob2text(blob) {
		return new Promise((resolve, reject) => {
		  const myReader = new FileReader();
		  myReader.readAsArrayBuffer(blob);
		  myReader.addEventListener('loadend', e => {
			const buffer = e.srcElement.result; // arraybuffer object
	
			const img = UPNG.decode(buffer); // put ArrayBuffer of the PNG file into UPNG.decode
	  
			const rgba = UPNG.toRGBA8(img)[0]; // UPNG.toRGBA8 returns array of frames, size: width * height * 4 bytes.
	
			const code = jsQR(new Uint8ClampedArray(rgba), img.width, img.height);
			
			if (code) {
			  resolve(code);
			} else {
			  reject(new Error('decode failed'));
			}
		  });
		});
	  }