feat: add hierarchical demo.

demo/Semi.Avalonia.TreeDataGrid.Demo/Converters/FileIconConverter.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using Avalonia;
+using Avalonia.Data.Converters;
+using Avalonia.Media;
+using Avalonia.Metadata;
+
+namespace Semi.Avalonia.TreeDataGrid.Demo.Converters;
+
+public class FileIconConverter: IMultiValueConverter
+{
+    [Content] 
+    public Dictionary<string, PathGeometry> Items { get; set; } = new Dictionary<string, PathGeometry>();
+
+    public object? Convert(IList<object?> values, Type targetType, object? parameter, CultureInfo culture)
+    {
+        if (values[0] is bool isDirectory && values[1] is bool isOpen)
+        {
+            if (!isDirectory)
+            {
+                return Items["file"];
+            }
+            return isOpen ? Items["folderOpen"] : Items["folderClosed"];
+        }
+        return AvaloniaProperty.UnsetValue;
+    }
+}

demo/Semi.Avalonia.TreeDataGrid.Demo/MainWindow.axaml

@@ -2,19 +2,128 @@
     x:Class="Semi.Avalonia.TreeDataGrid.Demo.MainWindow"
     xmlns="https://github.com/avaloniaui"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:converters="clr-namespace:Semi.Avalonia.TreeDataGrid.Demo.Converters"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:vm="clr-namespace:Semi.Avalonia.TreeDataGrid.Demo.ViewModels;assembly=Semi.Avalonia.TreeDataGrid.Demo"
     Title="Semi.Avalonia.TreeDataGrid.Demo"
     d:DesignHeight="450"
     d:DesignWidth="800"
-    x:DataType="vm:SongsPageViewModel"
+    x:DataType="vm:MainViewModel"
     mc:Ignorable="d">
+    <Window.Resources>
+        <converters:FileIconConverter x:Key="FileIconConverter">
+            <PathGeometry x:Key="file">M14,2H6A2,2 0 0,0 4,4V20A2,2 0 0,0 6,22H18A2,2 0 0,0 20,20V8L14,2M18,20H6V4H13V9H18V20Z</PathGeometry>
+            <PathGeometry x:Key="folderOpen">M6.1,10L4,18V8H21A2,2 0 0,0 19,6H12L10,4H4A2,2 0 0,0 2,6V18A2,2 0 0,0 4,20H19C19.9,20 20.7,19.4 20.9,18.5L23.2,10H6.1M19,18H6L7.6,12H20.6L19,18Z</PathGeometry>
+            <PathGeometry x:Key="folderClosed">M20,18H4V8H20M20,6H12L10,4H4C2.89,4 2,4.89 2,6V18A2,2 0 0,0 4,20H20A2,2 0 0,0 22,18V8C22,6.89 21.1,6 20,6Z</PathGeometry>
+        </converters:FileIconConverter>
+    </Window.Resources>
     <Grid RowDefinitions="Auto, *">
-        <Button Click="Button_OnClick" Content="Theme" />
+        <Button
+            HorizontalAlignment="Right"
+            Click="Button_OnClick"
+            Content="Theme" />
         <TabControl Grid.Row="1">
             <TabItem Header="Songs">
-                <TreeDataGrid Source="{Binding Songs}" />
+                <TreeDataGrid
+                    AutoDragDropRows="True"
+                    DataContext="{Binding SongsContext}"
+                    Source="{Binding Songs}">
+                    <TreeDataGrid.Resources>
+                        <DataTemplate x:Key="AlbumCell" DataType="vm:SongViewModel">
+                            <TextBlock
+                                HorizontalAlignment="Stretch"
+                                VerticalAlignment="Center"
+                                Background="Transparent"
+                                Text="{Binding Album}" />
+                        </DataTemplate>
+                        <DataTemplate x:Key="AlbumEditCell" DataType="vm:SongViewModel">
+                            <ComboBox
+                                VerticalAlignment="Center"
+                                Classes="Small"
+                                ItemsSource="{x:Static vm:Song.Albums}"
+                                SelectedItem="{Binding Album}" />
+                        </DataTemplate>
+                        <DataTemplate x:Key="CommentsCell" DataType="vm:SongViewModel">
+                            <TextBlock VerticalAlignment="Center" Text="{Binding CountOfComment}" />
+                        </DataTemplate>
+                        <DataTemplate x:Key="CommentsEditCell" DataType="vm:SongViewModel">
+                            <NumericUpDown
+                                Width="100"
+                                HorizontalAlignment="Left"
+                                VerticalAlignment="Center"
+                                Classes="Small"
+                                Value="{Binding CountOfComment}" />
+                        </DataTemplate>
+                    </TreeDataGrid.Resources>
+                    <TreeDataGrid.Styles>
+                        <Style Selector="TreeDataGrid TreeDataGridRow:nth-last-child(2n)">
+                            <Setter Property="Background" Value="#20808080" />
+                        </Style>
+                    </TreeDataGrid.Styles>
+                </TreeDataGrid>
+            </TabItem>
+            <TabItem Header="Files">
+                <Grid DataContext="{Binding FilesContext}" RowDefinitions="Auto, *">
+                    <DockPanel Margin="0,4" DockPanel.Dock="Top">
+                        <ComboBox
+                            DockPanel.Dock="Left"
+                            ItemsSource="{Binding Drives}"
+                            SelectedItem="{Binding SelectedDrive}" />
+                        <TextBox
+                            Margin="4,0,0,0"
+                            VerticalContentAlignment="Center"
+                            KeyDown="SelectedPath_KeyDown"
+                            Text="{Binding SelectedPath, Mode=OneWay}" />
+                    </DockPanel>
+                    <TreeDataGrid
+                        Name="fileViewer"
+                        Grid.Row="1"
+                        Source="{Binding Source}">
+                        <TreeDataGrid.Resources>
+
+                            <!--  Template for Name column cells  -->
+                            <DataTemplate x:Key="FileNameCell" DataType="vm:FileNodeViewModel">
+                                <StackPanel Orientation="Horizontal">
+                                    <PathIcon
+                                        Width="16"
+                                        Height="16"
+                                        Margin="8,0"
+                                        VerticalAlignment="Center">
+                                        <PathIcon.Data>
+                                            <MultiBinding Converter="{StaticResource FileIconConverter}">
+                                                <Binding Path="IsDirectory" />
+                                                <Binding Path="IsExpanded" />
+                                            </MultiBinding>
+                                        </PathIcon.Data>
+                                    </PathIcon>
+                                    <TextBlock VerticalAlignment="Center" Text="{Binding Name}" />
+                                </StackPanel>
+                            </DataTemplate>
+
+                            <!--  Edit template for Name column cells  -->
+                            <DataTemplate x:Key="FileNameEditCell" DataType="vm:FileNodeViewModel">
+                                <StackPanel Orientation="Horizontal">
+                                    <Image Margin="0,0,4,0" VerticalAlignment="Center">
+                                        <Image.Source>
+                                            <MultiBinding Converter="{StaticResource FileIconConverter}">
+                                                <Binding Path="IsDirectory" />
+                                                <Binding Path="IsExpanded" />
+                                            </MultiBinding>
+                                        </Image.Source>
+                                    </Image>
+                                    <TextBox VerticalAlignment="Center" Text="{Binding Name}" />
+                                </StackPanel>
+                            </DataTemplate>
+
+                        </TreeDataGrid.Resources>
+                        <TreeDataGrid.Styles>
+                            <Style Selector="TreeDataGrid TreeDataGridRow:nth-child(2n)">
+                                <Setter Property="Background" Value="#20808080" />
+                            </Style>
+                        </TreeDataGrid.Styles>
+                    </TreeDataGrid>
+                </Grid>
             </TabItem>
         </TabControl>
     </Grid>

demo/Semi.Avalonia.TreeDataGrid.Demo/MainWindow.axaml.cs

@@ -1,5 +1,6 @@
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Styling;
 using Semi.Avalonia.TreeDataGrid.Demo.ViewModels;
@@ -11,7 +12,7 @@ public partial class MainWindow : Window
     public MainWindow()
     {
         InitializeComponent();
-        this.DataContext = new SongsPageViewModel();
+        this.DataContext = new MainViewModel();
     }
 
     private void Button_OnClick(object? sender, RoutedEventArgs e)
@@ -23,4 +24,13 @@ public partial class MainWindow : Window
             app.RequestedThemeVariant = theme == ThemeVariant.Dark ? ThemeVariant.Light : ThemeVariant.Dark;
         }
     }
+    
+    private void SelectedPath_KeyDown(object? sender, KeyEventArgs e)
+    {
+        if (e.Key == Key.Enter)
+        {
+            var vm = (MainViewModel)DataContext!;
+            vm.FilesContext.SelectedPath = ((TextBox)sender!).Text;
+        }
+    }
 }

demo/Semi.Avalonia.TreeDataGrid.Demo/ViewModels/FilesPageViewModel.cs

@@ -1,7 +1,14 @@
+using System;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.ComponentModel;
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
+using Avalonia.Controls;
+using Avalonia.Controls.Models.TreeDataGrid;
+using Avalonia.Controls.Selection;
+using Avalonia.Threading;
 using CommunityToolkit.Mvvm.ComponentModel;
 
 namespace Semi.Avalonia.TreeDataGrid.Demo.ViewModels;
@@ -10,6 +17,26 @@ public class FilesPageViewModel: ObservableObject
 {
     public IList<string> Drives { get; }
     private string _selectedDrive;
+    private string? _selectedPath;
+    private FileNodeViewModel? _root;
+    public string SelectedDrive
+    {
+        get => _selectedDrive;
+        set
+        {
+            SetProperty(ref _selectedDrive, value);
+            _root = new FileNodeViewModel(_selectedDrive, isDirectory: true, isRoot: true);
+            Source.Items = new[] { _root };
+        }
+    }
+    
+    public string? SelectedPath
+    {
+        get => _selectedPath;
+        set => SetSelectedPath(value);
+    }
+    
+    public HierarchicalTreeDataGridSource<FileNodeViewModel> Source { get; }
 
     public FilesPageViewModel()
     {
@@ -22,5 +49,354 @@ public class FilesPageViewModel: ObservableObject
         {
             _selectedDrive = Drives.FirstOrDefault() ?? "/";
         }
+
+        Source = new HierarchicalTreeDataGridSource<FileNodeViewModel>(Array.Empty<FileNodeViewModel>())
+        {
+            Columns =
+            {
+                new CheckBoxColumn<FileNodeViewModel>(
+                    null,
+                    x => x.IsChecked,
+                    (o, v) => o.IsChecked = v,
+                    options: new()
+                    {
+                        CanUserResizeColumn = false,
+                    }),
+                new HierarchicalExpanderColumn<FileNodeViewModel>(
+                    new TemplateColumn<FileNodeViewModel>(
+                        "Name",
+                        "FileNameCell",
+                        "FileNameEditCell",
+                        new GridLength(1, GridUnitType.Star),
+                        new()
+                        {
+                            CompareAscending = FileNodeViewModel.SortAscending(x => x.Name),
+                            CompareDescending = FileNodeViewModel.SortDescending(x => x.Name),
+                            IsTextSearchEnabled = true,
+                            TextSearchValueSelector = x => x.Name
+                        }),
+                    x => x.Children,
+                    x => x.HasChildren,
+                    x => x.IsExpanded),
+                new TextColumn<FileNodeViewModel, long?>(
+                    "Size",
+                    x => x.Size,
+                    options: new()
+                    {
+                        CompareAscending = FileNodeViewModel.SortAscending(x => x.Size),
+                        CompareDescending = FileNodeViewModel.SortDescending(x => x.Size),
+                    }),
+                new TextColumn<FileNodeViewModel, DateTimeOffset?>(
+                    "Modified",
+                    x => x.Modified,
+                    options: new()
+                    {
+                        CompareAscending = FileNodeViewModel.SortAscending(x => x.Modified),
+                        CompareDescending = FileNodeViewModel.SortDescending(x => x.Modified),
+                    }),
+            }
+        };
+        Source.RowSelection!.SingleSelect = false;
+        Source.RowSelection.SelectionChanged += SelectionChanged;
+    }
+    
+    private void SelectionChanged(object? sender, TreeSelectionModelSelectionChangedEventArgs<FileNodeViewModel> e)
+    {
+        var selectedPath = Source.RowSelection?.SelectedItem?.Path;
+        this.SetProperty(ref _selectedPath, selectedPath, nameof(SelectedPath));
+
+        foreach (var i in e.DeselectedItems)
+            System.Diagnostics.Trace.WriteLine($"Deselected '{i?.Path}'");
+        foreach (var i in e.SelectedItems)
+            System.Diagnostics.Trace.WriteLine($"Selected '{i?.Path}'");
+    }
+    
+    private void SetSelectedPath(string? value)
+    {
+        if (string.IsNullOrEmpty(value))
+        {
+            Source.RowSelection!.Clear();
+            return;
+        }
+
+        var path = value;
+        var components = new Stack<string>();
+        DirectoryInfo? d = null;
+
+        if (File.Exists(path))
+        {
+            var f = new FileInfo(path);
+            components.Push(f.Name);
+            d = f.Directory;
+        }
+        else if (Directory.Exists(path))
+        {
+            d = new DirectoryInfo(path);
+        }
+
+        while (d is not null)
+        {
+            components.Push(d.Name);
+            d = d.Parent;
+        }
+
+        var index = IndexPath.Unselected;
+
+        if (components.Count > 0)
+        {
+            var drive = components.Pop();
+            var driveIndex = Drives.FindIndex(x => string.Equals(x, drive, StringComparison.OrdinalIgnoreCase));
+
+            if (driveIndex >= 0)
+                SelectedDrive = Drives[driveIndex];
+
+            FileNodeViewModel? node = _root;
+            index = new IndexPath(0);
+
+            while (node is not null && components.Count > 0)
+            {
+                node.IsExpanded = true;
+
+                var component = components.Pop();
+                var i = node.Children.FindIndex(x => string.Equals(x.Name, component, StringComparison.OrdinalIgnoreCase));
+                node = i >= 0 ? node.Children[i] : null;
+                index = i >= 0 ? index.Append(i) : default;
+            }
+        }
+
+        Source.RowSelection!.SelectedIndex = index;
+    }
+}
+
+public class FileNodeViewModel: ObservableObject, IEditableObject
+{
+    private string _path;
+        private string _name;
+        private string? _undoName;
+        private long? _size;
+        private DateTimeOffset? _modified;
+        private FileSystemWatcher? _watcher;
+        private ObservableCollection<FileNodeViewModel>? _children;
+        private bool _hasChildren = true;
+        private bool _isExpanded;
+
+        public FileNodeViewModel(
+            string path,
+            bool isDirectory,
+            bool isRoot = false)
+        {
+            _path = path;
+            _name = isRoot ? path : System.IO.Path.GetFileName(Path);
+            _isExpanded = isRoot;
+            IsDirectory = isDirectory;
+            HasChildren = isDirectory;
+
+            if (!isDirectory)
+            {
+                var info = new FileInfo(path);
+                Size = info.Length;
+                Modified = info.LastWriteTimeUtc;
+            }
+        }
+
+        public string Path 
+        {
+            get => _path;
+            private set => SetProperty(ref _path, value);
+        }
+
+        public string Name 
+        {
+            get => _name;
+            private set => SetProperty(ref _name, value);
+        }
+
+        public long? Size 
+        {
+            get => _size;
+            private set => SetProperty(ref _size, value);
+        }
+
+        public DateTimeOffset? Modified 
+        {
+            get => _modified;
+            private set => SetProperty(ref _modified, value);
+        }
+
+        public bool HasChildren
+        {
+            get => _hasChildren;
+            private set => SetProperty(ref _hasChildren, value);
+        }
+
+        public bool IsExpanded
+        {
+            get => _isExpanded;
+            set => SetProperty(ref _isExpanded, value);
+        }
+
+        public bool IsChecked { get; set; }
+        public bool IsDirectory { get; }
+        public IReadOnlyList<FileNodeViewModel> Children => _children ??= LoadChildren();
+
+        private ObservableCollection<FileNodeViewModel> LoadChildren()
+        {
+            if (!IsDirectory)
+            {
+                throw new NotSupportedException();
+            }
+
+            var options = new EnumerationOptions { IgnoreInaccessible = true };
+            var result = new ObservableCollection<FileNodeViewModel>();
+
+            foreach (var d in Directory.EnumerateDirectories(Path, "*", options))
+            {
+                result.Add(new FileNodeViewModel(d, true));
+            }
+
+            foreach (var f in Directory.EnumerateFiles(Path, "*", options))
+            {
+                result.Add(new FileNodeViewModel(f, false));
+            }
+
+            _watcher = new FileSystemWatcher
+            {
+                Path = Path,
+                NotifyFilter = NotifyFilters.FileName | NotifyFilters.Size | NotifyFilters.LastWrite,
+            };
+
+            _watcher.Changed += OnChanged;
+            _watcher.Created += OnCreated;
+            _watcher.Deleted += OnDeleted;
+            _watcher.Renamed += OnRenamed;
+            _watcher.EnableRaisingEvents = true;
+
+            if (result.Count == 0)
+                HasChildren = false;
+
+            return result;
+        }
+
+        public static Comparison<FileNodeViewModel?> SortAscending<T>(Func<FileNodeViewModel, T> selector)
+        {
+            return (x, y) =>
+            {
+                if (x is null && y is null)
+                    return 0;
+                else if (x is null)
+                    return -1;
+                else if (y is null)
+                    return 1;
+                if (x.IsDirectory == y.IsDirectory)
+                    return Comparer<T>.Default.Compare(selector(x), selector(y));
+                else if (x.IsDirectory)
+                    return -1;
+                else
+                    return 1;
+            };
+        }
+
+        public static Comparison<FileNodeViewModel?> SortDescending<T>(Func<FileNodeViewModel, T> selector)
+        {
+            return (x, y) =>
+            {
+                if (x is null && y is null)
+                    return 0;
+                else if (x is null)
+                    return 1;
+                else if (y is null)
+                    return -1;
+                if (x.IsDirectory == y.IsDirectory)
+                    return Comparer<T>.Default.Compare(selector(y), selector(x));
+                else if (x.IsDirectory)
+                    return -1;
+                else
+                    return 1;
+            };
+        }
+
+        void IEditableObject.BeginEdit() => _undoName = _name;
+        void IEditableObject.CancelEdit() => _name = _undoName!;
+        void IEditableObject.EndEdit() => _undoName = null;
+
+        private void OnChanged(object sender, FileSystemEventArgs e)
+        {
+            if (e.ChangeType == WatcherChangeTypes.Changed && File.Exists(e.FullPath))
+            {
+                Dispatcher.UIThread.Post(() =>
+                {
+                    foreach (var child in _children!)
+                    {
+                        if (child.Path == e.FullPath)
+                        {
+                            if (!child.IsDirectory)
+                            {
+                                var info = new FileInfo(e.FullPath);
+                                child.Size = info.Length;
+                                child.Modified = info.LastWriteTimeUtc;
+                            }
+                            break;
+                        }
+                    }
+                });
+            }
+        }
+
+        private void OnCreated(object sender, FileSystemEventArgs e)
+        {
+            Dispatcher.UIThread.Post(() =>
+            {
+                var node = new FileNodeViewModel(
+                    e.FullPath,
+                    File.GetAttributes(e.FullPath).HasFlag(FileAttributes.Directory));
+                _children!.Add(node);
+            });
+        }
+
+        private void OnDeleted(object sender, FileSystemEventArgs e)
+        {
+            Dispatcher.UIThread.Post(() =>
+            {
+                for (var i = 0; i < _children!.Count; ++i)
+                {
+                    if (_children[i].Path == e.FullPath)
+                    {
+                        _children.RemoveAt(i);
+                        System.Diagnostics.Debug.WriteLine($"Removed {e.FullPath}");
+                        break;
+                    }
+                }
+            });
+        }
+
+        private void OnRenamed(object sender, RenamedEventArgs e)
+        {
+            Dispatcher.UIThread.Post(() =>
+            {
+                foreach (var child in _children!)
+                {
+                    if (child.Path == e.OldFullPath)
+                    {
+                        child.Path = e.FullPath;
+                        child.Name = e.Name ?? string.Empty;
+                        break;
+                    }
+                }
+            });
+        }
+}
+
+internal static class ListExtensions
+{
+    public static int FindIndex<T>(this IEnumerable<T> source, Func<T, bool> predicate)
+    {
+        int i = 0;
+        foreach (var item in source)
+        {
+            if (predicate(item))
+                return i;
+            i++;
+        }
+        return -1;
     }
 }

demo/Semi.Avalonia.TreeDataGrid.Demo/ViewModels/MainViewModel.cs

@@ -4,5 +4,6 @@ namespace Semi.Avalonia.TreeDataGrid.Demo.ViewModels;
 
 public class MainViewModel: ObservableObject
 {
-    
+    public SongsPageViewModel SongsContext { get; } = new();
+    public FilesPageViewModel FilesContext { get; } = new();
 }

demo/Semi.Avalonia.TreeDataGrid.Demo/ViewModels/SongsPageViewModel.cs

@@ -21,15 +21,21 @@ public class SongsPageViewModel: ObservableObject
             Title = a.Title, Artist = a.Artist, Album = a.Album, CountOfComment = a.CountOfComment,
             IsSelected = false
         }));
-        
+
         Songs = new FlatTreeDataGridSource<SongViewModel>(_songs)
         {
             Columns =
             {
-                new CheckBoxColumn<SongViewModel>("IsSelected", a=>a.IsSelected, (model, b) => { model.IsSelected = b; }, new GridLength(72, GridUnitType.Pixel)),
-                new TextColumn<SongViewModel,string>("Title", a=>a.Title, (o, a) => o.Title = a, new GridLength(6, GridUnitType.Star)),
-                new TextColumn<SongViewModel,string>("Artist", a=>a.Artist, (o, a) => o.Artist = a, new GridLength(6, GridUnitType.Star)),
-                new TextColumn<SongViewModel,string>("Album", a=>a.Album, (o, a) => o.Album = a, new GridLength(6, GridUnitType.Star)),
+                new CheckBoxColumn<SongViewModel>("IsSelected", a => a.IsSelected,
+                    (model, b) => { model.IsSelected = b; }, new GridLength(108, GridUnitType.Pixel)),
+                new TextColumn<SongViewModel, string>("Title", a => a.Title, (o, a) => o.Title = a,
+                    new GridLength(6, GridUnitType.Star)),
+                new TextColumn<SongViewModel, string>("Artist", a => a.Artist, (o, a) => o.Artist = a,
+                    new GridLength(6, GridUnitType.Star)),
+                new TemplateColumn<SongViewModel>("Album", "AlbumCell", "AlbumEditCell",
+                    new GridLength(6, GridUnitType.Star)),
+                new TemplateColumn<SongViewModel>("Comments", "CommentsCell", "CommentsEditCell",
+                    new GridLength(6, GridUnitType.Star)),
             }
         };
     }
@@ -57,6 +63,25 @@ public class Song
         
     }
 
+    public static List<string> Albums { get; set; } = new List<string>()
+    {
+        "A.S.I.A",
+        "饕餮人间",
+        "七步咙咚呛",
+        "大惊小怪",
+        "The ONE",
+        "以梦为马 (壮志骄阳版)",
+        "emo了",
+        "一眼万年",
+        "冲刺吧",
+        "爱的赏味期限",
+        "COSMIC ANTHEM / 手紙",
+        "世界晚安",
+        "明年也要好好长大",
+        "320万年前",
+        "W.O.R.L.D.",
+    };
+
     public static List<Song> Songs { get; set; } = new List<Song>()
     {
         new("好肚有肚(feat.李玲玉)", "熊猫堂ProducePandas", 2, 50, "A.S.I.A", 730, 1487039339),