WPF DataGrid behavior customize command and command parameter then invoke and implemented in MVVM

Install-Package Microsoft.Xaml.Behaviors.WPF

 

public class DataGridBehavior : Behavior<DataGrid>
{
    private ContextMenu ctxMenu;
    private MenuItem saveItem;

    public DataGridBehavior()
    {

    }



    public ICommand SaveCommand
    {
        get { return (ICommand)GetValue(SaveCommandProperty); }
        set { SetValue(SaveCommandProperty, value); }
    }

    // Using a DependencyProperty as the backing store for SaveCommand.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SaveCommandProperty =
        DependencyProperty.Register(nameof(SaveCommand), typeof(ICommand), typeof(DataGridBehavior),
            new PropertyMetadata(null));




    public object CmdPara
    {
        get { return (object)GetValue(CmdParaProperty); }
        set { SetValue(CmdParaProperty, value); }
    }

    // Using a DependencyProperty as the backing store for CmdPara.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty CmdParaProperty =
        DependencyProperty.Register(nameof(CmdPara), typeof(object), typeof(DataGridBehavior),
            new PropertyMetadata(null));



    protected override void OnAttached()
    {
        base.OnAttached();
        CreateContextMenu();
    }

    private void CreateContextMenu()
    {
        ctxMenu = new ContextMenu();
        saveItem = new MenuItem()
        {
            Header = "Save"
        };
        saveItem.Click += SaveItem_Click;
        ctxMenu.Items.Add(saveItem);
        AssociatedObject.ContextMenu = ctxMenu;
    }

    private void SaveItem_Click(object sender, RoutedEventArgs e)
    {
        SaveCommand?.Execute(CmdPara);
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if(saveItem!=null)
        {
            saveItem.Click -= SaveItem_Click;
            saveItem = null;
        }

        if(ctxMenu!=null)
        {
            ctxMenu.Items.Clear();
            ctxMenu = null;
        }

        AssociatedObject.ContextMenu = null;
    }
}

            <behavior:Interaction.Behaviors>
                <local:DataGridBehavior SaveCommand="{Binding DataContext.SaveCmd,RelativeSource={RelativeSource AncestorType=Window}}"
                                        CmdPara="{Binding Path=ItemsSource,RelativeSource={RelativeSource AncestorType=DataGrid}}"/>
            </behavior:Interaction.Behaviors>



public ICommand SaveCmd { get; set;  }
SaveCmd = new DelCommand(SaveCmdExecuted);


private void SaveCmdExecuted(object? obj)
{
    var items = ((System.Collections.IList)obj)?.Cast<Book>()?.ToList(); 
    if(items!=null && items.Any())
    {
        MessageBox.Show($"Command paramenters:{items.Count} items", $"{DateTime.Now}");
    }
}

 

 

<Window x:Class="WpfApp21.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:behavior="http://schemas.microsoft.com/xaml/behaviors"
        xmlns:local="clr-namespace:WpfApp21"
        mc:Ignorable="d"
        Title="{Binding MainTitle}" WindowState="Maximized">
    <Window.DataContext>
        <local:MainVM/>
    </Window.DataContext>
    <Window.Resources>
        <local:ImgUrlConverter x:Key="ImgUrlConverter"/>
    </Window.Resources>
    <Grid>
        <DataGrid ItemsSource="{Binding BooksCollection}"
                  VirtualizingPanel.IsVirtualizing="True"
                  VirtualizingPanel.VirtualizationMode="Recycling"
                  VirtualizingPanel.CacheLength="2,2"
                  VirtualizingPanel.CacheLengthUnit="Item"
                  ScrollViewer.IsDeferredScrollingEnabled="True"
                  ScrollViewer.CanContentScroll="True"
                  UseLayoutRounding="True"
                  SnapsToDevicePixels="True"
                  EnableColumnVirtualization="True"
                  EnableRowVirtualization="True"
                  CanUserAddRows="False"
                  IsReadOnly="True"
                  AutoGenerateColumns="False">
            <DataGrid.Columns>
                <DataGridTemplateColumn>
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <Grid Width="{x:Static SystemParameters.FullPrimaryScreenWidth}"
                                  Height="{x:Static SystemParameters.FullPrimaryScreenHeight}">
                                <Grid.Resources>
                                    <Style TargetType="TextBlock">
                                        <Setter Property="FontSize" Value="50"/>
                                        <Style.Triggers>
                                            <Trigger Property="IsMouseOver" Value="True">
                                                <Setter Property="FontSize" Value="100"/>
                                                <Setter Property="Foreground" Value="Red"/>
                                            </Trigger>
                                        </Style.Triggers>
                                    </Style>
                                </Grid.Resources>
                                <Grid.RowDefinitions>
                                    <RowDefinition/>
                                    <RowDefinition/>
                                </Grid.RowDefinitions>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition/>
                                    <ColumnDefinition/>
                                </Grid.ColumnDefinitions>
                                <Image Source="{Binding ImgUrl,Converter={StaticResource ImgUrlConverter}}"
                                       Grid.Row="0" Grid.RowSpan="2"
                                       Grid.Column="0" Grid.ColumnSpan="2"/>
                                <TextBlock Text="{Binding Id}" Grid.Row="0" Grid.Column="0"/>
                                <TextBlock Text="{Binding Name}" Grid.Row="0" Grid.Column="1"/>
                                <TextBlock Text="{Binding ISBN}" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="2"/>
                            </Grid>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
            </DataGrid.Columns>
            <behavior:Interaction.Behaviors>
                <local:DataGridBehavior SaveCommand="{Binding DataContext.SaveCmd,RelativeSource={RelativeSource AncestorType=Window}}"
                                        CmdPara="{Binding Path=ItemsSource,RelativeSource={RelativeSource AncestorType=DataGrid}}"/>
            </behavior:Interaction.Behaviors>
        </DataGrid>
    </Grid>
</Window>



using Microsoft.Xaml.Behaviors;
using System.Collections.ObjectModel;
using System.ComponentModel;
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 WpfApp21
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }

    public class MainVM : INotifyPropertyChanged
    {
        public ICommand SaveCmd { get; set;  }
        public MainVM()
        {
            SaveCmd = new DelCommand(SaveCmdExecuted);
            Task.Run(async () =>
            {
                await InitBooksCollectionAsync();
            });
        }

        private void SaveCmdExecuted(object? obj)
        {
            var items = ((System.Collections.IList)obj)?.Cast<Book>()?.ToList(); 
            if(items!=null && items.Any())
            {
                MessageBox.Show($"Command paramenters:{items.Count} items", $"{DateTime.Now}");
            }
        }

        private async Task InitBooksCollectionAsync(int cnt = 10000000)
        {
            var imgDir = @"../../../Images";
            if (!Directory.Exists(imgDir))
            {
                return;
            }

            var imgs = Directory.GetFiles(imgDir);
            if (imgs == null || !imgs.Any())
            {
                return;
            }

            int imgsCnt = imgs.Count();
            BooksCollection = new ObservableCollection<Book>();
            List<Book> bksList = new List<Book>();

            for (int i = 1; i < cnt + 1; i++)
            {
                bksList.Add(new Book()
                {
                    Id = i,
                    Name = $"Name_{i}",
                    ISBN = $"ISBN_{i}_{Guid.NewGuid():N}",
                    ImgUrl = $"{imgs[i % imgsCnt]}"
                });

                if (i % 1000000 == 0)
                {
                    await PopulateBooksCollectionAsync(bksList);
                }
            }

            if (bksList.Any())
            {
                await PopulateBooksCollectionAsync(bksList);
            }
        }

        private async Task PopulateBooksCollectionAsync(List<Book> bksList)
        {
            await Application.Current.Dispatcher.InvokeAsync(() =>
            {
                var tempList = bksList.ToList();
                bksList.Clear();
                foreach (var bk in tempList)
                {
                    BooksCollection.Add(bk);
                }
                MainTitle = $"{DateTime.Now},loaded {BooksCollection.Count},{GetMem()}";
            }, System.Windows.Threading.DispatcherPriority.Background);
        }

        private string GetMem()
        {
            return $"memory {System.Diagnostics.Process.GetCurrentProcess().PrivateMemorySize64 / 1024 / 1024:N2}";
        }

        private string mainTitle = $"{DateTime.Now},loading...";
        public string MainTitle
        {
            get
            {
                return mainTitle;
            }
            set
            {
                if (value != mainTitle)
                {
                    mainTitle = value;
                    OnPropertyChanged();
                }
            }
        }

        private ObservableCollection<Book> booksCollection;
        public ObservableCollection<Book> BooksCollection
        {
            get
            {
                return booksCollection;
            }
            set
            {
                if (value != booksCollection)
                {
                    booksCollection = value;
                    OnPropertyChanged();
                }
            }
        }

        public event PropertyChangedEventHandler? PropertyChanged;
        public void OnPropertyChanged([CallerMemberName] string propName = "")
        {
            var handler = PropertyChanged;
            handler?.Invoke(this, new PropertyChangedEventArgs(propName));
        }
    }

    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?.Invoke(parameter);
        }
    }

    public class DataGridBehavior : Behavior<DataGrid>
    {
        private ContextMenu ctxMenu;
        private MenuItem saveItem;

        public DataGridBehavior()
        {

        }



        public ICommand SaveCommand
        {
            get { return (ICommand)GetValue(SaveCommandProperty); }
            set { SetValue(SaveCommandProperty, value); }
        }

        // Using a DependencyProperty as the backing store for SaveCommand.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty SaveCommandProperty =
            DependencyProperty.Register(nameof(SaveCommand), typeof(ICommand), typeof(DataGridBehavior),
                new PropertyMetadata(null));




        public object CmdPara
        {
            get { return (object)GetValue(CmdParaProperty); }
            set { SetValue(CmdParaProperty, value); }
        }

        // Using a DependencyProperty as the backing store for CmdPara.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty CmdParaProperty =
            DependencyProperty.Register(nameof(CmdPara), typeof(object), typeof(DataGridBehavior),
                new PropertyMetadata(null));



        protected override void OnAttached()
        {
            base.OnAttached();
            CreateContextMenu();
        }

        private void CreateContextMenu()
        {
            ctxMenu = new ContextMenu();
            saveItem = new MenuItem()
            {
                Header = "Save"
            };
            saveItem.Click += SaveItem_Click;
            ctxMenu.Items.Add(saveItem);
            AssociatedObject.ContextMenu = ctxMenu;
        }

        private void SaveItem_Click(object sender, RoutedEventArgs e)
        {
            SaveCommand?.Execute(CmdPara);
        }

        protected override void OnDetaching()
        {
            base.OnDetaching();

            if(saveItem!=null)
            {
                saveItem.Click -= SaveItem_Click;
                saveItem = null;
            }

            if(ctxMenu!=null)
            {
                ctxMenu.Items.Clear();
                ctxMenu = null;
            }

            AssociatedObject.ContextMenu = null;
        }
    }

    public class ImgUrlConverter : IValueConverter
    {
        private Dictionary<string, ImageSource> imgCache = new Dictionary<string, ImageSource>();
        private readonly object objLock = new object();

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var imgUrl = value?.ToString();
            if (string.IsNullOrWhiteSpace(imgUrl) || !File.Exists(imgUrl))
            {
                return null;
            }

            lock (objLock)
            {
                if (imgCache.TryGetValue(imgUrl, out ImageSource img))
                {
                    return img;
                }

                using (FileStream fs = new FileStream(imgUrl, FileMode.Open, FileAccess.Read, FileShare.Read))
                {
                    BitmapImage bmi = new BitmapImage();
                    bmi.BeginInit();
                    bmi.StreamSource = fs;
                    bmi.CacheOption = BitmapCacheOption.OnLoad;
                    bmi.EndInit();

                    if (bmi.CanFreeze)
                    {
                        bmi.Freeze();
                    }

                    imgCache.TryAdd(imgUrl, bmi);
                    return bmi;
                }
            }
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return DependencyProperty.UnsetValue;
        }
    }

    public class Book
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string ISBN { get; set; }
        public string ImgUrl { get; set; }

        public override string ToString()
        {
            return $"{DateTime.Now},Id:{Id},Name:{Name},ISBN:{ISBN}";
        }
    }
}