WPF Canvas Copy and paste via Clipboard

//xaml
<Window x:Class="WpfApp62.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        WindowState="Maximized"
        xmlns:local="clr-namespace:WpfApp62"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Canvas x:Name="cvs"
                PreviewMouseDown="cvs_PreviewMouseDown"
                PreviewMouseMove="cvs_PreviewMouseMove"
                PreviewMouseUp="cvs_PreviewMouseUp"/>
    </Grid>
</Window>



//cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
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 WpfApp62
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            InitData();
        }

        int idx = 0;
        private void InitData()
        {
            Ellipse elp = new Ellipse();
            elp.Width = 100;
            elp.Height = 100;
            elp.Fill = new SolidColorBrush(Colors.Red);
            elp.Stroke = new SolidColorBrush(Colors.Black);
            elp.StrokeThickness = 5;
            elp.ToolTip = $"{++idx},{Guid.NewGuid().ToString("N")}";
            Canvas.SetLeft(elp, 100);
            Canvas.SetTop(elp, 100);
            cvs.Children.Add(elp);
        }

        Ellipse capElp { get; set; }

        Point oldPt { get; set; }
        Point newPt { get; set; }

        private void cvs_PreviewMouseDown(object sender, MouseButtonEventArgs e)
        {
            var elp=e.Source as Ellipse;
            if(elp!=null)
            {
                capElp = elp;
                if(Keyboard.Modifiers == ModifierKeys.Control)
                {
                   
                    oldPt = e.GetPosition(cvs);
                }
            }
        }

        private void cvs_PreviewMouseMove(object sender, MouseEventArgs e)
        {
            if (capElp!=null && Mouse.LeftButton==MouseButtonState.Pressed)
            {
                var newPt = e.GetPosition(cvs);
                Canvas.SetLeft(capElp, newPt.X-50);
                Canvas.SetTop(capElp,newPt.Y-50);
                if (Keyboard.Modifiers == ModifierKeys.Control)
                {
                    Clipboard.SetData(DataFormats.Text, capElp.ToolTip);
                }
            }
        }

        private void cvs_PreviewMouseUp(object sender, MouseButtonEventArgs e)
        {
            if (capElp != null && Keyboard.IsKeyDown(Key.LeftCtrl))
            { 
                if (Clipboard.ContainsData(DataFormats.Text))
                {
                    string str = Clipboard.GetData(DataFormats.Text) as string;
                    if (!string.IsNullOrEmpty(str))
                    {
                        newPt=e.GetPosition(cvs);
                        Canvas.SetLeft(capElp,oldPt.X-50);
                        Canvas.SetTop(capElp,oldPt.Y-50);
                        Ellipse newElp = new Ellipse();
                        newElp.Width = 100;
                        newElp.Height = 100;
                        newElp.ToolTip = $"{++idx}_Pasted,{Guid.NewGuid().ToString("N")}";
                        newElp.Fill = new SolidColorBrush(Colors.Blue);
                        newElp.Stroke = new SolidColorBrush(Colors.Black);
                        newElp.StrokeThickness = 5;
                        if(!cvs.Children.Contains(newElp))
                        {
                            Canvas.SetLeft(newElp,newPt.X-50);
                            Canvas.SetTop(newElp,newPt.Y-50);
                            cvs.Children.Add(newElp);
                        }
                    }
                }
            }
        }
    }
}