// QR-Code
  var track;

  function readQR() {
    removeQRCodeLink();
    var video = document.getElementById('webcamVideo');
    setupVideo(video);
    //Scanner
    let scanner = new Instascan.Scanner({
      video
    });

    //Listens for valid QRCode read by webcam
    scanner.addListener('scan', function(content) {
      qrCode_content = content; // content returns QRCode
      $.fn.getXMLData("qrCode");
      //stop scanning
      stopScan(scanner);
      addQRCodeLink();
    });

    //Again, ask for camera access, check if camera was found ...
    Instascan.Camera.getCameras().then(function(cameras) {
      if (cameras.length > 0) {
        scanner.start(cameras[0]); //Start scanning on first webcam
      } else {
        alert("No cameras found.");
      }
    }).catch(function(e) {
      alert("Error opening camera");
    });
  }

  function setupVideo(video) {
    //Access Camera to get Stream to play video
    navigator.mediaDevices.getUserMedia({
      video: true,
      audio: false
    })
    .then(function(stream) {
      track = stream;
      video.srcObject = track;
      video.play();
    })
    .catch(function(err) {
      console.log("An error occured! " + err);
    });
//video dimensions
    var width = 400;
    var height = 0;

    height = video.videoHeight / (video.videoWidth / width); //height ist abhängig von stream width(hor oder ver)

    video.setAttribute('width', width);
    video.setAttribute('height', height);
  }

  function stopScan(scanner) {
    scanner.stop();
    var video = document.getElementById('webcamVideo');
    stopStreamedVideo(video);
  }

  function removeQRCodeLink() {
    /var qrcodeSection = document.getElementById('qrVideoDiv');
    qrcodeSection.removeChild(document.getElementById('qrCodeLink'));/
    var qrCodeLink = $("#qrCodeLink");
    qrCodeLink.css("display", "none");
  }

  function addQRCodeLink() {
    /var a = document.createElement("a");
    a.setAttribute("id", "qrCodeLink");
    a.setAttribute("href", "javascript:readQR()");
    var img = document.createElement("img");
    img.setAttribute("src", "res/img/qrcode.png");
    img.setAttribute("alt", "Press to Scan QR Code");
    a.appendChild(img);
    var qrCodeSection = document.getElementById('roomsQrCode');
    qrCodeSection.insertAdjacentElement('afterbegin', a);/
    var qrCodeLink = $("#qrCodeLink");
    qrCodeLink.css("display", "inline");
  }

  function stopStreamedVideo(videoElem) {
    let stream = videoElem.srcObject;
    let tracks = stream.getTracks();

    tracks.forEach(function(track) {
      track.stop();
    });

    videoElem.src = null;

  }