WPF RenderTargetBitmap DrawingVisual DrawingContext DrawImage DrawRectangle DrawEllipse DrawText DrawGeometry

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp166
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private VisualCollection childrenValue;
        public MainWindow()
        {
            InitializeComponent();
            this.Loaded += MainWindow_Loaded;
        }         

        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            Image img = new Image();
            img.Source = DrawingVisualContextRenderBmp();
            this.Content = img;
        } 

        private ImageSource DrawingVisualContextRenderBmp()
        {
            int width = (int)this.ActualWidth;
            int height = (int)this.ActualHeight;
            RenderTargetBitmap renderBmp = new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Default);
            DrawingVisual visual = new DrawingVisual();
            using (DrawingContext context = visual.RenderOpen())
            {
                context.DrawEllipse(new SolidColorBrush(Colors.Black),
                   new Pen(new SolidColorBrush(Colors.Blue), 5),
                   new Point(600, 500), 200, 200);
                context.DrawRectangle(new SolidColorBrush(Colors.Red),
                    new Pen(new SolidColorBrush(Colors.Blue), 5), 
                    new Rect(0, 0, 400, 400)); 
                context.DrawImage(new BitmapImage(new Uri(@"..\..\cl1.jpg",UriKind.RelativeOrAbsolute)),
                    new Rect(900, 200, 500, 500)); 
                context.DrawText(
                    new FormattedText("Draw Text", CultureInfo.InvariantCulture,
                    FlowDirection.LeftToRight, new Typeface("Verdana"), 96,
                    new SolidColorBrush(Colors.Cyan),1.25),
                    new Point(700, 700));
                context.DrawGeometry(new SolidColorBrush(Colors.Red),
                    new Pen(new SolidColorBrush(Colors.Black), 5),
                    new LineGeometry(new Point(100,900),new Point(1200,900)));
            }
            renderBmp.Render(visual);
            return renderBmp;
        }  
    }
}