WPF canvas locate

//xaml
<Window x:Class="WpfApp210.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"
        xmlns:local="clr-namespace:WpfApp210"
        mc:Ignorable="d" WindowState="Maximized"
        Title="{Binding LocatedPt,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
        Height="450" Width="800">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="200"/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <DataGrid Grid.Column="0" x:Name="dg" 
            ItemsSource="{Binding BooksList,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
            SelectionChanged="dg_SelectionChanged" />
        <Canvas Grid.Column="1" x:Name="cvs" ClipToBounds="True"/>
    </Grid>
</Window>


//cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
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 WpfApp210
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window, INotifyPropertyChanged
    {
        public MainWindow()
        {
            InitializeComponent();
            
            this.Loaded += MainWindow_Loaded;
            this.DataContext = this;
        }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(string propName)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler?.Invoke(this, new PropertyChangedEventArgs(propName));
            }
        }

        private ObservableCollection<Book> booksList;
        public ObservableCollection<Book> BooksList
        {
            get
            {
                return booksList;
            }
            set
            {
                if (value != booksList)
                {
                    booksList = value;
                    OnPropertyChanged(nameof(BooksList));
                }
            }
        }

        private string locatedPt;
        public string LocatedPt
        {
            get
            {
                return locatedPt;
            }
            set
            {
                if(value!= locatedPt) 
                {
                    locatedPt = value;
                    OnPropertyChanged(nameof(LocatedPt));
                }
            }
        }

        Ellipse markedElp { get; set; }

        private void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            double width = this.ActualWidth-200;
            double height = this.ActualHeight;
            Random rnd = new Random();
            BooksList = new ObservableCollection<Book>();
            for (int i = 0; i < 200; i++)
            {
                int ptX = rnd.Next(0, (int)width - 30);
                int ptY = rnd.Next(0, (int)height - 30);

                BooksList.Add(new Book()
                {
                    Id = i + 1,
                    Name = $"Name_{i + 1}",
                    Pt = new Point(ptX, ptY)
                });
                Ellipse elp = new Ellipse();
                elp.Width = 30;
                elp.Height = 30;
                elp.StrokeThickness = 5;
                elp.Stroke = new SolidColorBrush(Colors.Cyan);
                //elp.Fill = new SolidColorBrush(Colors.Cyan);
                Canvas.SetLeft(elp, ptX);
                Canvas.SetTop(elp, ptY);
                cvs.Children.Add(elp);
            }

            markedElp = new Ellipse();
            markedElp.Width = 50;
            markedElp.Height = 50;
            markedElp.Stroke = new SolidColorBrush(Colors.Red);
            markedElp.StrokeThickness = 15;
            markedElp.Fill = new SolidColorBrush(Colors.Transparent);
        }

        private void DrawEllipses()
        {

        }

        private void dg_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if(dg.SelectedItem!=null)
            {
                var bk=dg.SelectedItem as Book;
                if(bk!=null)
                { 
                    Canvas.SetLeft(markedElp, bk.Pt.X-10);
                    Canvas.SetTop(markedElp, bk.Pt.Y-10);
                    if(cvs.Children.Contains(markedElp))
                    {
                        cvs.Children.Remove(markedElp);
                    }
                    cvs.Children.Add(markedElp);
                    LocatedPt = $"({bk.Pt.X},{bk.Pt.Y})";
                }
            }
        }
    }

    public class Book
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public Point Pt { get; set; }
    }
}