我想实现它，如图所示。(在WPF中绘制对角线)

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;

namespace WpfApp
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DrawDiagonal();
        }

        private void DrawDiagonal()
        {
            Line diagonal = new Line();
            diagonal.Stroke = Brushes.Black;
            diagonal.X1 = 0;
            diagonal.Y1 = 0;
            diagonal.X2 = canvas.ActualWidth;
            diagonal.Y2 = canvas.ActualHeight;
            canvas.Children.Add(diagonal);
        }
    }
}