Xamarin.Forms RadBarcode to Bitmap

MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:telerikBarcode="clr-namespace:Telerik.XamarinForms.Barcode;assembly=Telerik.XamarinForms.Barcode"
             x:Class="BarcodeCanvasToBitmap.Portable.MainPage">

    <Grid>
        <telerikBarcode:RadBarcode x:Name="barcode"
                                   Value="https://www.telerik.com/xamarin-ui"
                                   WidthRequest="100"
                                   HeightRequest="100">
            <telerikBarcode:RadBarcode.Symbology>
                <telerikBarcode:QRCode SizingMode="Stretch" />
            </telerikBarcode:RadBarcode.Symbology>
        </telerikBarcode:RadBarcode>

        <Button Text="Export As PNG"
                HorizontalOptions="Center"
                Margin="0,0,0,10"
                VerticalOptions="End"
                Clicked="Button_OnClicked" />
    </Grid>
</ContentPage>

MainPage.xaml.cs

using System;
using System.IO;
using System.Linq;
using SkiaSharp;
using SkiaSharp.Views.Forms;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

[assembly:XamlCompilation(XamlCompilationOptions.Compile)]
namespace BarcodeCanvasToBitmap.Portable
{
    public partial class MainPage : ContentPage
    {
        private SKPixmap pixmap;

        public MainPage()
        {
            InitializeComponent();

            // Get a reference to the SKCanvasView inside the RadBarcode
            SKCanvasView canvasView = barcode.Children.FirstOrDefault(c => c.GetType() == typeof(SKCanvasView)) as SKCanvasView;

            // subscribe to the PaintSurface event
            if(canvasView != null)
            {
                canvasView.PaintSurface += CanvasView_PaintSurface;
            }
        }

        private async void Button_OnClicked(object sender, EventArgs e)
        {
            // Choose the format you want the image in
            var chosenImageFormat = SKEncodedImageFormat.Png;

            // Use SKManagedStream, this will prevent you from needing pointers!
            using (MemoryStream ms = new MemoryStream())
            using (SKManagedWStream ws = new SKManagedWStream(ms))
            {
                // Get the image from the pixel map, encoded as your chosen image file format
                pixmap.Encode(ws, chosenImageFormat, 90);

                // Get the byte array from the stream
                byte[] encodedImageBytes = ms.ToArray();

                // Save the byte array to a file. this example saves it to the platform's app local folder
                // Install "CommonHelpers" NuGet package to class library project
                await CommonHelpers.Extensions.FileExtensions.SaveToLocalFolderAsync(encodedImageBytes, $"Barcode.{chosenImageFormat}");
            }
        }

        private void CanvasView_PaintSurface(object sender, SKPaintSurfaceEventArgs e)
        {
            // after the canvas is painted, you can get a pixel map
            this.pixmap = e.Surface.PeekPixels();
        }
    }
}