title: Xamarin Forms QR code scanner blank screen
body: <p>I have a Xamarin Forms 2.0 application that uses ZXing.Net.Mobile and ZXing.Net.Mobile.Forms version 2.0.3.1. I'm trying to build a simple QR code scanner, but whenever I launch the <code>ZXingScannerPage</code> on Android I can see the default overlay (with the text and the red line) but I don't see the output of the camera so I can't actually scan anything. I have already listed the Camera permission in my AndroidManifest:</p>
  
  <pre><code>&lt;uses-permission android:name="android.permission.CAMERA" /&gt;
  </code></pre>
  
  <p>I tried the sample code from the readme: <a href="https://github.com/Redth/ZXing.Net.Mobile" rel="nofollow">https://github.com/Redth/ZXing.Net.Mobile</a> as well as from their Samples/Forms project. I now have this code:</p>
  
  <pre><code>private async void OnScanQrClicked(object sender, EventArgs e)
  {
      _scannerPage = new ZXingScannerPage();
      _scannerPage.OnScanResult += HandleScanResult;
  
      await Navigation.PushAsync(_scannerPage);
  }
  
  private void HandleScanResult(Result result)
  {
      _scannerPage.IsScanning = false;
  
      Device.BeginInvokeOnMainThread(() =&gt;
      {
          Navigation.PopAsync();
          DisplayAlert("Scanned code", result.Text, "OK");
      });
  }
  </code></pre>
  
  <p>Some more specs: I'm running Android 5.1 on a Moto G (v1).</p>
  
  <p>Why am I not seeing the output of the camera?</p>