WPF implement DelCommand inherited from ICommand from scratch

public class DelCommand : ICommand
{private Action<object?> execute;private Predicate<object?> canExecute;public DelCommand(Action<object?> executeValue, Predicate<object?> canExecuteValue =null){execute = executeValue;canExecute = canExecuteValue;}public event EventHandler? CanExecuteChanged{add{CommandManager.RequerySuggested += value;}remove{CommandManager.RequerySuggested -= value;}}public bool CanExecute(object? parameter){return canExecute == null ? true : canExecute(parameter);}public void Execute(object? parameter){execute(parameter);}
}

 

 

 

<Window x:Class="WpfApp1.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:WpfApp1"mc:Ignorable="d"WindowState="Maximized"Title="{Binding MainTitle}"><Window.DataContext><local:MainVM/></Window.DataContext><Window.Resources><local:ImgUrlToImageSourceConverter x:Key="ImgUrlToImageSourceConverter"/>        </Window.Resources><Grid><DataGrid ItemsSource="{Binding BooksCollection}"VirtualizingPanel.IsVirtualizing="True"VirtualizingPanel.VirtualizationMode="Recycling"VirtualizingPanel.CacheLength="2,2"VirtualizingPanel.CacheLengthUnit="Item"ScrollViewer.CanContentScroll="True"ScrollViewer.IsDeferredScrollingEnabled="True"AutoGenerateColumns="False"CanUserAddRows="False"><DataGrid.Columns><DataGridTemplateColumn><DataGridTemplateColumn.CellTemplate><DataTemplate><Grid Width="{Binding DataContext.GridWidth,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"Height="{Binding DataContext.GridHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"><Grid.Resources><Style TargetType="TextBlock"><Setter Property="FontSize" Value="30"/><Style.Triggers><Trigger Property="IsMouseOver" Value="True"><Setter Property="Foreground" Value="Red"/><Setter Property="FontSize" Value="100"/></Trigger></Style.Triggers></Style></Grid.Resources><Grid.Background><ImageBrush ImageSource="{Binding ImgUrl,Converter={StaticResource ImgUrlToImageSourceConverter}}"Stretch="Uniform"/></Grid.Background><Grid.RowDefinitions><RowDefinition/><RowDefinition/></Grid.RowDefinitions><Grid.ColumnDefinitions><ColumnDefinition/><ColumnDefinition/><ColumnDefinition/></Grid.ColumnDefinitions><TextBlock Grid.Row="0" Grid.Column="0" Text="{Binding Id}"/><TextBlock Grid.Row="0" Grid.Column="1" Text="{Binding Name}"/><TextBlock Grid.Row="0" Grid.Column="2" Text="{Binding Topic}"/><TextBlock Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="3" Text="{Binding ISBN}"/></Grid></DataTemplate></DataGridTemplateColumn.CellTemplate></DataGridTemplateColumn></DataGrid.Columns></DataGrid></Grid>
</Window>using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text;
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 WpfApp1
{/// <summary>/// Interaction logic for MainWindow.xaml/// </summary>public partial class MainWindow : Window{public MainWindow(){InitializeComponent();RenderOptions.ProcessRenderMode=System.Windows.Interop.RenderMode.Default;this.Loaded += async (s, e) =>{var vm = this.DataContext as MainVM;if(vm!=null){var fe = this.Content as FrameworkElement;if(fe!=null){vm.GridWidth= fe.ActualWidth;vm.GridHeight= fe.ActualHeight;}await vm.InitBooksCollection(30500100);}};}}public class MainVM : INotifyPropertyChanged{public MainVM(){}public async Task InitBooksCollection(int cnt=10000000){var img_dir = @"../../../Images";if (!Directory.Exists(img_dir)){return;}var imgs=Directory.GetFiles(img_dir);if(imgs==null ||!imgs.Any()){return;}int imgsCnt = imgs.Count();List<Book> booksList=new List<Book>();BooksCollection = new ObservableCollection<Book>();for (int i=0;i<cnt+1;i++){booksList.Add(new Book(){Id=i,Name=$"Name_{i}",ISBN=$"ISBN_{i}_{Guid.NewGuid():N}",Topic=$"Topic_{i}",ImgUrl = imgs[i%imgsCnt]});if (i%100000==0){await PopulateBooksCollectionAsync(booksList, i);}}if(booksList.Any()){await PopulateBooksCollectionAsync(booksList, cnt);}}private async Task PopulateBooksCollectionAsync(List<Book> booksList, int i){var tempList = booksList.ToList();booksList.Clear();            await Application.Current.Dispatcher.InvokeAsync(() =>{foreach (var item in tempList){BooksCollection.Add(item);}MainTitle = $"{DateTime.Now},i:{i},{GetMem()}";},System.Windows.Threading.DispatcherPriority.Background);}private ObservableCollection<Book> booksCollection;public ObservableCollection<Book> BooksCollection{get{return booksCollection; }set{if (booksCollection != value){booksCollection = value;OnPropertyChanged();}}}private double gridWidth;public double GridWidth{get{return gridWidth; }set{if (gridWidth != value){gridWidth = value;OnPropertyChanged();}}}private double gridHeight;public double GridHeight{get{return gridHeight; }set{if(gridHeight!=value){gridHeight = value;OnPropertyChanged();}}}private string mainTitle="";public string MainTitle{get{return mainTitle; }set{if(mainTitle!=value){mainTitle = value;OnPropertyChanged();}}}public string GetMem(){var proc=Process.GetCurrentProcess();return $"Memory {proc.PrivateMemorySize64 / 1024 / 1024:.2f}M";}public event PropertyChangedEventHandler? PropertyChanged;private void OnPropertyChanged([CallerMemberName]string propertyName=""){var handler = PropertyChanged;if(handler!=null){handler?.Invoke(this, new PropertyChangedEventArgs(propertyName));}}}public class ImgUrlToImageSourceConverter : IValueConverter{Dictionary<string,ImageSource> imgDic=new Dictionary<string,ImageSource>();public object Convert(object value, Type targetType, object parameter, CultureInfo culture){var imgUrl=value as string;if(!string.IsNullOrWhiteSpace(imgUrl) && File.Exists(imgUrl)){if(imgDic.ContainsKey(imgUrl)){return imgDic[imgUrl];}BitmapImage bmi=new BitmapImage();bmi.BeginInit();bmi.UriSource = new Uri(imgUrl, UriKind.RelativeOrAbsolute);bmi.CacheOption = BitmapCacheOption.OnDemand;bmi.EndInit();if(bmi.CanFreeze){bmi.Freeze();}imgDic[imgUrl] = bmi;return bmi;}return null;}public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture){throw new NotImplementedException();}}public class Book{public int Id { get; set; }public string Name { get; set; }public string Topic { get; set;  }public string ISBN { get; set; }public string ImgUrl { get; set;  }}public class DelCommand : ICommand{private Action<object?> execute;private Predicate<object?> canExecute;public DelCommand(Action<object?> executeValue, Predicate<object?> canExecuteValue =null){execute = executeValue;canExecute = canExecuteValue;}public event EventHandler? CanExecuteChanged{add{CommandManager.RequerySuggested += value;}remove{CommandManager.RequerySuggested -= value;}}public bool CanExecute(object? parameter){return canExecute == null ? true : canExecute(parameter);}public void Execute(object? parameter){execute(parameter);}}
}