添加项目文件。

gong-wpf-dragdrop/src/Showcase/ViewModels/MainViewModel.cs

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+using System.Diagnostics;
+using System.Windows.Data;
+using System.Windows.Input;
+using Showcase.WPF.DragDrop.Models;
+
+namespace Showcase.WPF.DragDrop.ViewModels
+{
+    using System.Collections.Generic;
+    using System.Collections.ObjectModel;
+
+    public class ListMember : List<SubMember>
+    {
+        public string Name { get; set; }
+    }
+
+    public class SubMember
+    {
+        public string Name { get; set; }
+    }
+
+    public class MainViewModel : ViewModelBase
+    {
+        private SampleData _data;
+        private ICommand _openIssueCommand;
+        private ICommand _openPullRequestCommand;
+        private ICommand _openLinkCommand;
+        private ICommand _filterCollectionCommand;
+
+        public ObservableCollection<ListMember> Members { get; set; } = new ObservableCollection<ListMember>();
+
+        /// <summary>
+        /// Initializes a new instance of the MainViewModel class.
+        /// </summary>
+        public MainViewModel()
+        {
+            ////if (IsInDesignMode)
+            ////{
+            ////    // Code runs in Blend --> create design time data.
+            ////}
+            ////else
+            ////{
+            ////    // Code runs "for real"
+            ////}
+
+            var listMember = new ListMember() { Name = "Item 1" };
+            Members.Add(listMember);
+
+            listMember = new ListMember() { Name = "Item 2 with SubItems" };
+            listMember.Add(new SubMember() { Name = "SubItem 1" });
+            listMember.Add(new SubMember() { Name = "SubItem 2" });
+            Members.Add(listMember);
+
+            listMember = new ListMember() { Name = "Item 3" };
+            Members.Add(listMember);
+
+            this.Data = new SampleData();
+            this.OpenIssueCommand = new SimpleCommand(issue => { Process.Start($"https://github.com/punker76/gong-wpf-dragdrop/issues/{issue}"); });
+            this.OpenPullRequestCommand = new SimpleCommand(pr => { Process.Start($"https://github.com/punker76/gong-wpf-dragdrop/pull/{pr}"); });
+            this.OpenLinkCommand = new SimpleCommand(link => { Process.Start(link.ToString()); });
+            this.FilterCollectionCommand = new SimpleCommand(isChecked =>
+                {
+                    var coll = Data.FilterCollection1;
+                    var collView = CollectionViewSource.GetDefaultView(coll);
+                    collView.Filter += o =>
+                        {
+                            if (!(isChecked as bool?).GetValueOrDefault())
+                            {
+                                return true;
+                            }
+                            var itemModel = (ItemModel)o;
+                            var number = itemModel.Index;
+                            return (number & 0x01) == 0;
+                        };
+                });
+        }
+
+        public SampleData Data
+        {
+            get { return _data; }
+            set
+            {
+                if (Equals(value, _data)) return;
+                _data = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public ICommand OpenIssueCommand
+        {
+            get { return _openIssueCommand; }
+            set
+            {
+                if (Equals(value, _openIssueCommand)) return;
+                _openIssueCommand = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public ICommand OpenPullRequestCommand
+        {
+            get { return _openPullRequestCommand; }
+            set
+            {
+                if (Equals(value, _openPullRequestCommand)) return;
+                _openPullRequestCommand = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public ICommand OpenLinkCommand
+        {
+            get { return _openLinkCommand; }
+            set
+            {
+                if (Equals(value, _openLinkCommand)) return;
+                _openLinkCommand = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public ICommand FilterCollectionCommand
+        {
+            get { return _filterCollectionCommand; }
+            set
+            {
+                if (Equals(value, _filterCollectionCommand)) return;
+                _filterCollectionCommand = value;
+                OnPropertyChanged();
+            }
+        }
+    }
+}

gong-wpf-dragdrop/src/Showcase/ViewModels/SimpleCommand.cs

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+using System;
+using System.Windows.Input;
+
+namespace Showcase.WPF.DragDrop.ViewModels
+{
+    public class SimpleCommand : ICommand
+    {
+        public SimpleCommand(Action<object> execute = null, Predicate<object> canExecute = null)
+        {
+            this.CanExecuteDelegate = canExecute;
+            this.ExecuteDelegate = execute;
+        }
+
+        public Predicate<object> CanExecuteDelegate { get; set; }
+
+        public Action<object> ExecuteDelegate { get; set; }
+
+        public bool CanExecute(object parameter)
+        {
+            var canExecute = this.CanExecuteDelegate;
+            return canExecute == null || canExecute(parameter);
+        }
+
+        public event EventHandler CanExecuteChanged
+        {
+            add { CommandManager.RequerySuggested += value; }
+            remove { CommandManager.RequerySuggested -= value; }
+        }
+
+        public void Execute(object parameter)
+        {
+            this.ExecuteDelegate?.Invoke(parameter);
+        }
+    }
+}

gong-wpf-dragdrop/src/Showcase/ViewModels/ViewModelBase.cs

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+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+using JetBrains.Annotations;
+
+namespace Showcase.WPF.DragDrop.ViewModels
+{
+    public class ViewModelBase : INotifyPropertyChanged
+    {
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        [NotifyPropertyChangedInvocator]
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}