title: How to merge two image in Xamarin Forms?
body: <p>I'm developing a Xamarin Forms iOS app. In the xaml file, there is a grid.</p>
  
  <pre><code>&lt;Grid x:Name="QrCodeSite" HeightRequest="300" Margin="37, 37, 37, 0"&gt;
  &lt;Grid.RowDefinitions&gt;
  &lt;RowDefinition Height="*" /&gt;
  &lt;/Grid.RowDefinitions&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>In the related .cs file, I use <code>ZXing.Net.Mobile.Forms</code> to generate a QR code and place it in the grid. And I put my logo in the same grid, which will finally appear at the center of the QR code.</p>
  
  <pre><code>var barcode = new ZXingBarcodeImageView
  {
  HorizontalOptions = LayoutOptions.FillAndExpand,
  VerticalOptions = LayoutOptions.FillAndExpand
  };
  barcode.BarcodeFormat = ZXing.BarcodeFormat.QR_CODE;
  barcode.BarcodeOptions.Width = 650;
  barcode.BarcodeOptions.Height = 650;
  barcode.BarcodeOptions.Margin = 1;
  barcode.BarcodeValue = value;
  
  
  var img = new Image
  {
  Source = "logo.png",
  WidthRequest = 70,
  HeightRequest = 70,
  VerticalOptions = LayoutOptions.Center,
  HorizontalOptions = LayoutOptions.Center
  };
  
  QrCodeSite.Children.Clear();
  
  QrCodeSite.Children.Add(barcode);
  QrCodeSite.Children.Add(img);
  </code></pre>
  
  <p>The problem is, maybe my phone (iPhone 6s plus) is too slow, sometimes the logo appears first and after a lag (around 1 second) the QR code is shown. How can I merge the QR code and the logo into one image and then add it to the grid? </p>