WPF ListBox mvvm contextmenu pass all and multiple items

 <MenuItem Header="Export All"
               Command="{Binding ExportAllCommand}"
               CommandParameter="{Binding RelativeSource={RelativeSource 
               Mode=FindAncestor,AncestorType={x:Type ContextMenu}},Path=PlacementTarget}" />

 <MenuItem Header="Export Selected"
               Command="{Binding ExportSelectedCommand}"
               CommandParameter="{Binding RelativeSource={RelativeSource 
               Mode=FindAncestor,AncestorType={x:Type ContextMenu}},Path=PlacementTarget.SelectedItems}" />

private void ExportAllCommandExecuted(object? obj)
{
var lbx = obj as ListBox;
if(lbx!=null)
{
var items =((System.Collections.IList)lbx.Items).Cast<Book>()?.ToList();
SaveListTAsJsonFile(items);
}
}

private void ExportSelectedCommandExecuted(object? obj)
{
var selectedItems = ((System.Collections.IList)obj)?.Cast<Book>()?.ToList();
SaveListTAsJsonFile(selectedItems);
}

 

 

1.
Install-package Microsoft.Xaml.Behaviors.Wpf
Install-package Newtonsoft.Json


2.
<Window x:Class="WpfApp43.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:i="http://schemas.microsoft.com/xaml/behaviors"
        xmlns:local="clr-namespace:WpfApp43"
        WindowState="Maximized"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid Background="#000000">
        <ListBox x:Name="lbx"
                 Focusable="True"                  
                 ItemsSource="{Binding BooksCollection,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                 SelectionMode="Extended">
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="SelectionChanged">
                    <i:CallMethodAction MethodName="ListBox_SelectionChanged"  
                             TargetObject="{Binding}"/>
                </i:EventTrigger>
                <i:EventTrigger EventName="PreviewMouseWheel">
                    <i:InvokeCommandAction Command="{Binding MouseWheelCommand}" 
                                           PassEventArgsToCommand="True"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
           
            
            <!--<ListBox.ItemsPanel>
                    <ItemsPanelTemplate>
                        <VirtualizingStackPanel Orientation="Vertical"/>
                    </ItemsPanelTemplate>
                </ListBox.ItemsPanel>-->
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <Grid.Background>
                                <ImageBrush ImageSource="{Binding ImgSource}"/>
                            </Grid.Background>
                        <Grid.Resources>
                            <Style TargetType="{x:Type Grid}">
                                <Setter Property="Height" Value="300"/>
                            </Style>
                            <Style TargetType="{x:Type TextBlock}">
                                <Setter Property="FontSize" Value="30"/>
                                <Setter Property="Foreground" Value="Black"/>
                                <Style.Triggers>
                                    <Trigger Property="IsMouseOver" Value="True">
                                        <Setter Property="FontSize" Value="80"/>
                                        <Setter Property="Foreground" Value="Red"/>
                                    </Trigger>
                                </Style.Triggers>
                            </Style>
                        </Grid.Resources>
                        <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 Title}"/>
                        <TextBlock Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="3" Text="{Binding ISBN}"/>
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.ContextMenu>
                <ContextMenu>

                    <MenuItem Header="Export All"
                                  Command="{Binding ExportAllCommand}"
                                  CommandParameter="{Binding RelativeSource={RelativeSource 
                                  Mode=FindAncestor,AncestorType={x:Type ContextMenu}},Path=PlacementTarget}" />

                    <MenuItem Header="Export Selected"
                                  Command="{Binding ExportSelectedCommand}"
                                  CommandParameter="{Binding RelativeSource={RelativeSource 
                                  Mode=FindAncestor,AncestorType={x:Type ContextMenu}},Path=PlacementTarget.SelectedItems}" />

                </ContextMenu>
            </ListBox.ContextMenu>
        </ListBox>

    </Grid>
</Window>



//cs
using Microsoft.Xaml.Behaviors;
using System.Collections;
using System.Collections.ObjectModel;
using System.ComponentModel;
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;
using Newtonsoft.Json;
using Microsoft.Win32;
using System.Windows.Controls.Primitives;

namespace WpfApp43
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {

            InitializeComponent();
            lbx.Items.Clear();
            var vm = new MainVM();
            this.DataContext = vm;
        }

        private void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            var lbx = sender as ListBox;
            if (lbx != null)
            {
                var items = lbx.SelectedItems;
            }
        }

        private void lbx_MouseWheel(object sender, MouseWheelEventArgs e)
        {

        }

        private void lbx_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
        {
            var bd = e.OriginalSource as Border;
            if (bd != null)
            {
                Console.WriteLine(bd.ActualHeight);
            }
        }
    }

    public class MainVM : INotifyPropertyChanged
    {
        public MainVM()
        {
            InitBooksCollection();
            //LbxMultiSelectCommand = new DelCommand(LbxMultiSelectCommandExecuted);
            ExportSelectedCommand = new DelCommand(ExportSelectedCommandExecuted);
            ExportAllCommand = new DelCommand(ExportAllCommandExecuted);
            MouseWheelCommand = new DelCommand(MouseWheelCommandExecuted);
        }

        private void MouseWheelCommandExecuted(object? obj)
        {
            
        }

        private void ExportAllCommandExecuted(object? obj)
        {
            var lbx = obj as ListBox;
            if(lbx!=null)
            {
                var items =((System.Collections.IList)lbx.Items).Cast<Book>()?.ToList();
                SaveListTAsJsonFile(items);
            }
        }

        private void ExportSelectedCommandExecuted(object? obj)
        {
            var selectedItems = ((System.Collections.IList)obj)?.Cast<Book>()?.ToList();
            SaveListTAsJsonFile(selectedItems);
        }

        private void SaveListTAsJsonFile<T>(List<T> dataList)
        {
            SaveFileDialog dialog = new SaveFileDialog();
            dialog.Filter = "Json Files|*.json|All Files|*.*";
            dialog.FileName = $"{DateTime.Now.ToString("yyyyMMddHHmmssffff")}_{Guid.NewGuid().ToString("N")}.json";
            if (dialog.ShowDialog() == true)
            {
                string jsonStr = JsonConvert.SerializeObject(dataList, Formatting.Indented);
                File.WriteAllText(dialog.FileName, jsonStr);
                MessageBox.Show($"Saved {dataList.Count} data in {dialog.FileName}");
            } 
        }

        public void lbx_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
        {

        }

        private void LbxMultiSelectCommandExecuted(object? obj)
        {

        }

        public void lbx_MouseWheel(object sender, MouseWheelEventArgs e)
        {

        }

        public void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            var lbx = sender as ListBox;
            if (lbx != null)
            {
                var items = lbx.SelectedItems;
            }
        }

        private void InitBooksCollection()
        {
            BooksCollection = new ObservableCollection<Book>();
            var dir = @"../../../Images";
            if (Directory.Exists(dir))
            {
                var imgs = Directory.GetFiles(dir);
                int imgsCount = imgs.Count();
                for (int i = 0; i < 1000; i++)
                {
                    BooksCollection.Add(new Book()
                    {
                        Id = i + 1,
                        Name = $"Name_{i + 1}",
                        Title = $"Title_{i + 1}",
                        ISBN = $"{Guid.NewGuid().ToString("N")}",
                        ImgSource = GetImgSourceVirUrl(imgs[i % imgsCount]),
                    });
                }
            }
        }

        private ImageSource GetImgSourceVirUrl(string imgUrl)
        {
            BitmapImage bmi = new BitmapImage();
            bmi.BeginInit();
            bmi.UriSource = new Uri(imgUrl, UriKind.RelativeOrAbsolute);
            bmi.EndInit();
            if (bmi.CanFreeze)
            {
                bmi.Freeze();
            }
            return bmi;
        }

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

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

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

        private bool isSelected;
        public bool IsSelected
        {
            get
            {
                return isSelected;
            }
            set
            {
                if (value != isSelected)
                {
                    isSelected = value;
                    OnPropertyChanged();
                }
            }
        }

        private IList _selectedItems;
        public IList SelectedItems
        {
            get => _selectedItems;
            set { _selectedItems = value; OnPropertyChanged(); }
        }

        public ICommand LbxMultiSelectCommand { get; set; }
        public ICommand ExportSelectedCommand { get; set; }
        public ICommand ExportAllCommand { get; set; }
        public ICommand MouseWheelCommand { get; set; }
    }


    public class DelCommand : ICommand
    {
        private Action<object?> execcute;
        private Predicate<object?> canExecute;
        public DelCommand(Action<object?> execcuteValue, Predicate<object?> canExecuteValue = null)
        {
            execcute = execcuteValue;
            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)
        {
            execcute(parameter);
        }
    }

    public class Book
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Title { get; set; }
        public string ISBN { get; set; }
        public ImageSource ImgSource { get; set; }
    }



}