/// <summary>
 /// Scan is finished.
 /// </summary>
 private void BarcodeScanner_FrameScanFinished(object sender, FrameScanFinishedEventArgs e)
 {
     ((Activity)Context).RunOnUiThread(() =>
     {
         OnFrameScanFinished(e);
     });
 }
 /// <summary>
 /// Frame scanning is finished.
 /// </summary>
 private void OnFrameScanFinished(FrameScanFinishedEventArgs e)
 {
     _barcodes = e.FoundBarcodes;
     Invalidate();
 }