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TreeViewをカスタマイズして複数選択を可能にする

組み込みのWPF TreeViewコントロールでは、ListBoxとは異なり、複数選択はできません。 TreeViewをカスタマイズして、再選択せずに複数選択できるようにする方法を教えてください。

wpftreeviewmulti-select
43
Dylan

ツリービューなどのコントロールの基本的な動作をオーバーライドすることを検討するときは、常に、自分の決定に関連する操作性と労力を考慮したいと思います。

ツリービューの特定のケースでは、0、1、またはそれ以上のコントロールと組み合わせてリストビューに切り替えると、実装が簡単になることが多い、より使いやすいソリューションになることがわかります。

例として、一般的な[開く]ダイアログまたはWindowsエクスプローラーアプリケーションを考えます。

6
Zamboni

基本のTreeViewコントロールの派生で宣言された添付プロパティを使用してTreeViewItemの選択状態を追跡するSoMoS実装のバリエーションがあります。これにより、TreeViewItem要素自体の選択の追跡が維持され、ツリービューによって提示されているモデルオブジェクトから除外されます。

これは、新しいTreeViewクラスの派生です。

using System.Linq;
using System.Windows;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Controls;
using System.Collections;
using System.Collections.Generic;

namespace MultiSelectTreeViewDemo
{
    public sealed class MultiSelectTreeView : TreeView
    {
        #region Fields

        // Used in shift selections
        private TreeViewItem _lastItemSelected;

        #endregion Fields
        #region Dependency Properties

        public static readonly DependencyProperty IsItemSelectedProperty =
            DependencyProperty.RegisterAttached("IsItemSelected", typeof(bool), typeof(MultiSelectTreeView));

        public static void SetIsItemSelected(UIElement element, bool value)
        {
            element.SetValue(IsItemSelectedProperty, value);
        }
        public static bool GetIsItemSelected(UIElement element)
        {
            return (bool)element.GetValue(IsItemSelectedProperty);
        }

        #endregion Dependency Properties
        #region Properties

        private static bool IsCtrlPressed
        {
            get { return Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl); }
        }
        private static bool IsShiftPressed
        {
            get { return Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift); }
        }

        public IList SelectedItems
        {
            get
            {
                var selectedTreeViewItems = GetTreeViewItems(this, true).Where(GetIsItemSelected);
                var selectedModelItems = selectedTreeViewItems.Select(treeViewItem => treeViewItem.Header);

                return selectedModelItems.ToList();
            }
        }

        #endregion Properties
        #region Event Handlers

        protected override void OnPreviewMouseDown(MouseButtonEventArgs e)
        {
            base.OnPreviewMouseDown(e);

            // If clicking on a tree branch expander...
            if (e.OriginalSource is Shape || e.OriginalSource is Grid || e.OriginalSource is Border)
                return;

            var item = GetTreeViewItemClicked((FrameworkElement)e.OriginalSource);
            if (item != null) SelectedItemChangedInternal(item);
        }

        #endregion Event Handlers
        #region Utility Methods

        private void SelectedItemChangedInternal(TreeViewItem tvItem)
        {
            // Clear all previous selected item states if ctrl is NOT being held down
            if (!IsCtrlPressed)
            {
                var items = GetTreeViewItems(this, true);
                foreach (var treeViewItem in items)
                    SetIsItemSelected(treeViewItem, false);
            }

            // Is this an item range selection?
            if (IsShiftPressed && _lastItemSelected != null)
            {
                var items = GetTreeViewItemRange(_lastItemSelected, tvItem);
                if (items.Count > 0)
                {
                    foreach (var treeViewItem in items)
                        SetIsItemSelected(treeViewItem, true);

                    _lastItemSelected = items.Last();
                }
            }
            // Otherwise, individual selection
            else
            {
                SetIsItemSelected(tvItem, true);
                _lastItemSelected = tvItem;
            }
        }
        private static TreeViewItem GetTreeViewItemClicked(DependencyObject sender)
        {
            while (sender != null && !(sender is TreeViewItem))
                sender = VisualTreeHelper.GetParent(sender);
            return sender as TreeViewItem;
        }
        private static List<TreeViewItem> GetTreeViewItems(ItemsControl parentItem, bool includeCollapsedItems, List<TreeViewItem> itemList = null)
        {
            if (itemList == null)
                itemList = new List<TreeViewItem>();

            for (var index = 0; index < parentItem.Items.Count; index++)
            {
                var tvItem = parentItem.ItemContainerGenerator.ContainerFromIndex(index) as TreeViewItem;
                if (tvItem == null) continue;

                itemList.Add(tvItem);
                if (includeCollapsedItems || tvItem.IsExpanded)
                    GetTreeViewItems(tvItem, includeCollapsedItems, itemList);
            }
            return itemList;
        }
        private List<TreeViewItem> GetTreeViewItemRange(TreeViewItem start, TreeViewItem end)
        {
            var items = GetTreeViewItems(this, false);

            var startIndex = items.IndexOf(start);
            var endIndex = items.IndexOf(end);
            var rangeStart = startIndex > endIndex || startIndex == -1 ? endIndex : startIndex;
            var rangeCount = startIndex > endIndex ? startIndex - endIndex + 1 : endIndex - startIndex + 1;

            if (startIndex == -1 && endIndex == -1)
                rangeCount = 0;

            else if (startIndex == -1 || endIndex == -1)
                rangeCount = 1;

            return rangeCount > 0 ? items.GetRange(rangeStart, rangeCount) : new List<TreeViewItem>();
        }

        #endregion Utility Methods
    }
}

そして、これがXAMLです。突出部分は、単一の「IsSelected」プロパティを使用する2つのトリガーを、MultiSelectTreeViewItemStyleの新しい「IsItemSelected」添付プロパティに置き換えて、視覚的な状態を実現することに注意してください。

また、新しいTreeViewコントロールをUserControlに集約していないことに注意してください。

<Window 
    x:Class="MultiSelectTreeViewDemo.MainWindow"
    xmlns="http://schemas.Microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.Microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:MultiSelectTreeViewDemo"
    Title="MultiSelect TreeView Demo" Height="350" Width="525">

    <Window.Resources>
        <local:DemoViewModel x:Key="ViewModel"/>
        <Style x:Key="TreeViewItemFocusVisual">
            <Setter Property="Control.Template">
                <Setter.Value>
                    <ControlTemplate>
                        <Rectangle/>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Checked.Fill" Color="#FF595959"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Checked.Stroke" Color="#FF262626"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Stroke" Color="#FF1BBBFA"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Fill" Color="Transparent"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Checked.Stroke" Color="#FF262626"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.MouseOver.Checked.Fill" Color="#FF595959"/>
        <PathGeometry x:Key="TreeArrow" Figures="M0,0 L0,6 L6,0 z"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Fill" Color="Transparent"/>
        <SolidColorBrush x:Key="TreeViewItem.TreeArrow.Static.Stroke" Color="#FF989898"/>
        <Style x:Key="ExpandCollapseToggleStyle" TargetType="{x:Type ToggleButton}">
            <Setter Property="Focusable" Value="False"/>
            <Setter Property="Width" Value="16"/>
            <Setter Property="Height" Value="16"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type ToggleButton}">
                        <Border Background="Transparent" Height="16" Padding="5,5,5,5" Width="16">
                            <Path x:Name="ExpandPath" Data="{StaticResource TreeArrow}" Fill="{StaticResource TreeViewItem.TreeArrow.Static.Fill}" Stroke="{StaticResource TreeViewItem.TreeArrow.Static.Stroke}">
                                <Path.RenderTransform>
                                    <RotateTransform Angle="135" CenterY="3" CenterX="3"/>
                                </Path.RenderTransform>
                            </Path>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsChecked" Value="True">
                                <Setter Property="RenderTransform" TargetName="ExpandPath">
                                    <Setter.Value>
                                        <RotateTransform Angle="180" CenterY="3" CenterX="3"/>
                                    </Setter.Value>
                                </Setter>
                                <Setter Property="Fill" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.Static.Checked.Fill}"/>
                                <Setter Property="Stroke" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.Static.Checked.Stroke}"/>
                            </Trigger>
                            <Trigger Property="IsMouseOver" Value="True">
                                <Setter Property="Stroke" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Stroke}"/>
                                <Setter Property="Fill" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Fill}"/>
                            </Trigger>
                            <MultiTrigger>
                                <MultiTrigger.Conditions>
                                    <Condition Property="IsMouseOver" Value="True"/>
                                    <Condition Property="IsChecked" Value="True"/>
                                </MultiTrigger.Conditions>
                                <Setter Property="Stroke" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Checked.Stroke}"/>
                                <Setter Property="Fill" TargetName="ExpandPath" Value="{StaticResource TreeViewItem.TreeArrow.MouseOver.Checked.Fill}"/>
                            </MultiTrigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <Style x:Key="MultiSelectTreeViewItemStyle" TargetType="{x:Type TreeViewItem}">
            <Setter Property="Background" Value="Transparent"/>
            <Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
            <Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
            <Setter Property="Padding" Value="1,0,0,0"/>
            <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
            <Setter Property="FocusVisualStyle" Value="{StaticResource TreeViewItemFocusVisual}"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type TreeViewItem}">
                        <Grid>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition MinWidth="19" Width="Auto"/>
                                <ColumnDefinition Width="Auto"/>
                                <ColumnDefinition Width="*"/>
                            </Grid.ColumnDefinitions>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition/>
                            </Grid.RowDefinitions>
                            <ToggleButton 
                                x:Name="Expander" 
                                ClickMode="Press" 
                                IsChecked="{Binding IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" 
                                Style="{StaticResource ExpandCollapseToggleStyle}"/>
                            <Border 
                                x:Name="Bd" 
                                BorderBrush="{TemplateBinding BorderBrush}" 
                                BorderThickness="{TemplateBinding BorderThickness}" 
                                Background="{TemplateBinding Background}" 
                                Grid.Column="1" 
                                Padding="{TemplateBinding Padding}" 
                                SnapsToDevicePixels="true">
                                <ContentPresenter 
                                    x:Name="PART_Header" 
                                    ContentSource="Header" 
                                    HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" 
                                    SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                            </Border>
                            <ItemsPresenter 
                                x:Name="ItemsHost" 
                                Grid.ColumnSpan="2" 
                                Grid.Column="1" 
                                Grid.Row="1"/>
                        </Grid>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsExpanded" Value="false">
                                <Setter Property="Visibility" TargetName="ItemsHost" Value="Collapsed"/>
                            </Trigger>
                            <Trigger Property="HasItems" Value="false">
                                <Setter Property="Visibility" TargetName="Expander" Value="Hidden"/>
                            </Trigger>
                            <!--Trigger Property="IsSelected" Value="true"-->
                            <Trigger Property="local:MultiSelectTreeView.IsItemSelected" Value="true">
                                <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
                                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
                            </Trigger>
                            <MultiTrigger>
                                <MultiTrigger.Conditions>
                                    <!--Condition Property="IsSelected" Value="true"/-->
                                    <Condition Property="local:MultiSelectTreeView.IsItemSelected" Value="true"/>
                                    <Condition Property="IsSelectionActive" Value="false"/>
                                </MultiTrigger.Conditions>
                                <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
                                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightTextBrushKey}}"/>
                            </MultiTrigger>
                            <Trigger Property="IsEnabled" Value="false">
                                <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            <Style.Triggers>
                <Trigger Property="VirtualizingPanel.IsVirtualizing" Value="true">
                    <Setter Property="ItemsPanel">
                        <Setter.Value>
                            <ItemsPanelTemplate>
                                <VirtualizingStackPanel/>
                            </ItemsPanelTemplate>
                        </Setter.Value>
                    </Setter>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>

    <Grid
        Background="WhiteSmoke"
        DataContext="{DynamicResource ViewModel}">
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <local:MultiSelectTreeView
            x:Name="multiSelectTreeView"
            ItemContainerStyle="{StaticResource MultiSelectTreeViewItemStyle}"
            ItemsSource="{Binding FoodGroups}">
            <local:MultiSelectTreeView.ItemTemplate>
                <HierarchicalDataTemplate ItemsSource="{Binding Children}">
                    <Grid>
                        <TextBlock FontSize="14" Text="{Binding Name}"/>
                    </Grid>
                </HierarchicalDataTemplate>
            </local:MultiSelectTreeView.ItemTemplate>
        </local:MultiSelectTreeView>
        <Button 
            Grid.Row="1" 
            Margin="0,10" 
            Padding="20,2"
            HorizontalAlignment="Center"
            Content="Get Selections" 
            Click="GetSelectionsButton_OnClick"/>
    </Grid>
</Window>

そして、これを駆動するための安っぽいビューモデルがあります（デモ用）。

using System.Collections.ObjectModel;

namespace MultiSelectTreeViewDemo
{
    public sealed class DemoViewModel
    {
        public ObservableCollection<FoodItem> FoodGroups { get; set; }

        public DemoViewModel()
        {
            var redMeat = new FoodItem { Name = "Reds" };
            redMeat.Add(new FoodItem { Name = "Beef" });
            redMeat.Add(new FoodItem { Name = "Buffalo" });
            redMeat.Add(new FoodItem { Name = "Lamb" });

            var whiteMeat = new FoodItem { Name = "Whites" };
            whiteMeat.Add(new FoodItem { Name = "Chicken" });
            whiteMeat.Add(new FoodItem { Name = "Duck" });
            whiteMeat.Add(new FoodItem { Name = "Pork" });
            var meats = new FoodItem { Name = "Meats", Children = { redMeat, whiteMeat } };

            var veggies = new FoodItem { Name = "Vegetables" };
            veggies.Add(new FoodItem { Name = "Potato" });
            veggies.Add(new FoodItem { Name = "Corn" });
            veggies.Add(new FoodItem { Name = "Spinach" });

            var fruits = new FoodItem { Name = "Fruits" };
            fruits.Add(new FoodItem { Name = "Apple" });
            fruits.Add(new FoodItem { Name = "Orange" });
            fruits.Add(new FoodItem { Name = "Pear" });

            FoodGroups = new ObservableCollection<FoodItem> { meats, veggies, fruits };
        }
    }
    public sealed class FoodItem
    {
        public string Name { get; set; }
        public ObservableCollection<FoodItem> Children { get; set; }

        public FoodItem()
        {
            Children = new ObservableCollection<FoodItem>();
        }
        public void Add(FoodItem item)
        {
            Children.Add(item);
        }
    }
}

そして、ここに、メッセージボックスの選択を表示するMainWindowコードビハインドのボタンクリックハンドラがあります。

    private void GetSelectionsButton_OnClick(object sender, RoutedEventArgs e)
    {
        var selectedMesg = "";
        var selectedItems = multiSelectTreeView.SelectedItems;

        if (selectedItems.Count > 0)
        {
            selectedMesg = selectedItems.Cast<FoodItem>()
                .Where(modelItem => modelItem != null)
                .Aggregate(selectedMesg, (current, modelItem) => current + modelItem.Name + Environment.NewLine);
        }
        else
            selectedMesg = "No selected items!";

        MessageBox.Show(selectedMesg, "MultiSelect TreeView Demo", MessageBoxButton.OK);
    }

お役に立てれば。

6
Nishan Hossepian

各ツリービューアイテムのテキストの前にチェックボックスを追加するこのタスクを簡略化しました。

そこで、チェックボックス+テキストブロックの2つの項目を含むドックパネルを作成しました。

そう...

[〜＃〜] xaml [〜＃〜]

<TreeView x:Name="treeViewProcesso" Margin="1,30.351,1,5"  BorderBrush="{x:Null}" MinHeight="250" VerticalContentAlignment="Top" BorderThickness="0" >
  <TreeViewItem Header="Documents" x:Name="treeView" IsExpanded="True" DisplayMemberPath="DocumentsId" >            
  </TreeViewItem>
</TreeView>

[〜＃〜] cs [〜＃〜]

TreeViewItem treeViewItem = new TreeViewItem();
DockPanel dp = new DockPanel();
CheckBox cb = new CheckBox();
TextBlock tb = new TextBlock();
tb.Text = "Item";
dp.Children.Add(cb);
dp.Children.Add(tb);
treeViewItem.Header = dp;
treeViewItem.Selected += new RoutedEventHandler(item_Selected);
treeView.Items.Add(treeViewItem);

そして、チェックボックスの値にアクセスできます：

void item_Selected(object sender, RoutedEventArgs e)
{
  selectedTVI = ((TreeViewItem)sender);

  CheckBox cb = (Checkbox)((DockPanel)selectedTVI.Header).Children[0];
}

これは、複雑なものが必要ない場合の簡単な方法です。

3
Web Developer

最終的に、内部にTreeViewを含む独自のCustomControlのコーディングを終了しました。他の人の作業に基づいて、機能のキーはTreeViewのモデルのすべての項目にISelectableインターフェースを継承させることにあります：

public interface ISelectable
{
    public bool IsSelected {get; set}
}

このようにして、TreeViewItem IsSelectedとは何の関係もない新しい 'IsSelected'プロパティを取得します。ツリーのスタイルを設定して、モデルのIsSelectedプロパティを処理するだけです。ここでコード（それは http://code.google.com/p/gong-wpf-dragdrop/ で利用可能なドラッグ＆ドロップライブラリを使用しています）：

XAML

<UserControl x:Class="Picis.Wpf.Framework.ExtendedControls.TreeViewEx.TreeViewEx"

         xmlns="http://schemas.Microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.Microsoft.com/winfx/2006/xaml"
         xmlns:DragAndDrop="clr-namespace:Picis.Wpf.Framework.DragAndDrop">

<TreeView ItemsSource="{Binding ItemsSource, RelativeSource={RelativeSource AncestorType=UserControl}}" 
          ItemTemplate="{Binding ItemTemplate, RelativeSource={RelativeSource AncestorType=UserControl}}" 
          ItemContainerStyle="{Binding ItemContainerStyle, RelativeSource={RelativeSource AncestorType=UserControl}}" 
          DragAndDrop:DragDrop.DropHandler ="{Binding DropHandler, RelativeSource={RelativeSource AncestorType=UserControl}}" 
          PreviewMouseDown="TreeViewOnPreviewMouseDown" 
          PreviewMouseUp="TreeViewOnPreviewMouseUp"
          x:FieldModifier="private" x:Name="InnerTreeView" >
    <TreeView.Resources>
        <Style TargetType="TreeViewItem">
            <Style.Resources>
                <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="White" />
                <SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="Black" />
                <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="White" />
            </Style.Resources>
        </Style>
    </TreeView.Resources>
</TreeView>

C＃：

using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;
using GongSolutions.Wpf.DragDrop;
using DragDrop = GongSolutions.Wpf.DragDrop;

namespace <yournamespace>.TreeViewEx
{
public partial class TreeViewEx : UserControl
{
    #region Attributes

    private TreeViewItem _lastItemSelected; // Used in shift selections
    private TreeViewItem _itemToCheck; // Used when clicking on a selected item to check if we want to deselect it or to drag the current selection
    private bool _isDragEnabled;
    private bool _isDropEnabled;

    #endregion

    #region Dependency Properties

    public static readonly DependencyProperty ItemsSourceProperty = DependencyProperty.Register("ItemsSource", typeof(IEnumerable<ISelectable>), typeof(TreeViewEx));

    public IEnumerable<ISelectable> ItemsSource
    {
        get
        {
            return (IEnumerable<ISelectable>)this.GetValue(TreeViewEx.ItemsSourceProperty);
        }
        set
        {
            this.SetValue(TreeViewEx.ItemsSourceProperty, value);
        }
    }

    public static readonly DependencyProperty ItemTemplateProperty = DependencyProperty.Register("ItemTemplate", typeof(DataTemplate), typeof(TreeViewEx));

    public DataTemplate ItemTemplate
    {
        get
        {
            return (DataTemplate)GetValue(TreeViewEx.ItemTemplateProperty);
        }
        set
        {
            SetValue(TreeViewEx.ItemTemplateProperty, value);
        }
    }

    public static readonly DependencyProperty ItemContainerStyleProperty = DependencyProperty.Register("ItemContainerStyle", typeof(Style), typeof(TreeViewEx));

    public Style ItemContainerStyle
    {
        get
        {
            return (Style)GetValue(TreeViewEx.ItemContainerStyleProperty);
        }
        set
        {
            SetValue(TreeViewEx.ItemContainerStyleProperty, value);
        }
    }

    public static readonly DependencyProperty DropHandlerProperty = DependencyProperty.Register("DropHandler", typeof(IDropTarget), typeof(TreeViewEx));

    public IDropTarget DropHandler
    {
        get
        {
            return (IDropTarget)GetValue(TreeViewEx.DropHandlerProperty);
        }
        set
        {
            SetValue(TreeViewEx.DropHandlerProperty, value);
        }
    }

    #endregion

    #region Properties

    public bool IsDragEnabled
    {
        get
        {
            return _isDragEnabled;
        }
        set
        {
            if (_isDragEnabled != value)
            {
                _isDragEnabled = value;
                DragDrop.SetIsDragSource(this.InnerTreeView, _isDragEnabled);
            }
        }
    }

    public bool IsDropEnabled
    {
        get
        {
            return _isDropEnabled;
        }
        set
        {
            if (_isDropEnabled != value)
            {
                _isDropEnabled = value;
                DragDrop.SetIsDropTarget(this.InnerTreeView, _isDropEnabled);
            }
        }
    }

    #endregion

    #region Public Methods

    public TreeViewEx()
    {
        InitializeComponent();
    }

    #endregion

    #region Event Handlers

    private void TreeViewOnPreviewMouseDown(object sender, MouseButtonEventArgs e)
    {
        if (e.OriginalSource is Shape || e.OriginalSource is Grid || e.OriginalSource is Border) // If clicking on the + of the tree
            return;

        TreeViewItem item = this.GetTreeViewItemClicked((FrameworkElement)e.OriginalSource);

        if (item != null && item.Header != null)
        {
            this.SelectedItemChangedHandler(item);
        }
    }

    // Check done to avoid deselecting everything when clicking to drag
    private void TreeViewOnPreviewMouseUp(object sender, MouseButtonEventArgs e)
    {
        if (_itemToCheck != null)
        {
            TreeViewItem item = this.GetTreeViewItemClicked((FrameworkElement)e.OriginalSource);

            if (item != null && item.Header != null)
            {
                if (!TreeViewEx.IsCtrlPressed)
                {
                    GetTreeViewItems(true).Select(t => t.Header).Cast<ISelectable>().ToList().ForEach(f => f.IsSelected = false);
                    ((ISelectable)_itemToCheck.Header).IsSelected = true;
                    _lastItemSelected = _itemToCheck;
                }
                else
                {
                    ((ISelectable)_itemToCheck.Header).IsSelected = false;
                    _lastItemSelected = null;
                }
            }
        }
    }

    #endregion

    #region Private Methods

    private void SelectedItemChangedHandler(TreeViewItem item)
    {
        ISelectable content = (ISelectable)item.Header;

        _itemToCheck = null;

        if (content.IsSelected)
        {
            // Check it at the mouse up event to avoid deselecting everything when clicking to drag
            _itemToCheck = item;
        }
        else
        {
            if (!TreeViewEx.IsCtrlPressed)
            {
                GetTreeViewItems(true).Select(t => t.Header).Cast<ISelectable>().ToList().ForEach(f => f.IsSelected = false);
            }

            if (TreeViewEx.IsShiftPressed && _lastItemSelected != null)
            {
                foreach (TreeViewItem tempItem in GetTreeViewItemsBetween(_lastItemSelected, item))
                {
                    ((ISelectable)tempItem.Header).IsSelected = true;
                    _lastItemSelected = tempItem;
                }
            }
            else
            {
                content.IsSelected = true;
                _lastItemSelected = item;
            }
        }
    }

    private static bool IsCtrlPressed
    {
        get
        {
            return Keyboard.IsKeyDown(Key.LeftCtrl) || Keyboard.IsKeyDown(Key.RightCtrl);
        }
    }

    private static bool IsShiftPressed
    {
        get
        {
            return Keyboard.IsKeyDown(Key.LeftShift) || Keyboard.IsKeyDown(Key.RightShift);
        }
    }

    private TreeViewItem GetTreeViewItemClicked(UIElement sender)
    {
        Point point = sender.TranslatePoint(new Point(0, 0), this.InnerTreeView);
        DependencyObject visualItem = this.InnerTreeView.InputHitTest(point) as DependencyObject;
        while (visualItem != null && !(visualItem is TreeViewItem))
        {
            visualItem = VisualTreeHelper.GetParent(visualItem);
        }

        return visualItem as TreeViewItem;
    }

    private IEnumerable<TreeViewItem> GetTreeViewItemsBetween(TreeViewItem start, TreeViewItem end)
    {
        List<TreeViewItem> items = this.GetTreeViewItems(false);

        int startIndex = items.IndexOf(start);
        int endIndex = items.IndexOf(end);

        // It's possible that the start element has been removed after it was selected,
        // I don't find a way to happen on the end but I add the code to handle the situation just in case
        if (startIndex == -1 && endIndex == -1)
        {
            return new List<TreeViewItem>();
        }
        else if (startIndex == -1)
        {
            return new List<TreeViewItem>() {end};
        }
        else if (endIndex == -1)
        {
            return new List<TreeViewItem>() { start };
        }
        else
        {
            return startIndex > endIndex ? items.GetRange(endIndex, startIndex - endIndex + 1) : items.GetRange(startIndex, endIndex - startIndex + 1); 
        }
    }

    private List<TreeViewItem> GetTreeViewItems(bool includeCollapsedItems)
    {
        List<TreeViewItem> returnItems = new List<TreeViewItem>();

        for (int index = 0; index < this.InnerTreeView.Items.Count; index++)
        {
            TreeViewItem item = (TreeViewItem)this.InnerTreeView.ItemContainerGenerator.ContainerFromIndex(index);
            returnItems.Add(item);
            if (includeCollapsedItems || item.IsExpanded)
            {
                returnItems.AddRange(GetTreeViewItemItems(item, includeCollapsedItems));                    
            }
        }

        return returnItems;
    }

    private static IEnumerable<TreeViewItem> GetTreeViewItemItems(TreeViewItem treeViewItem, bool includeCollapsedItems)
    {
        List<TreeViewItem> returnItems = new List<TreeViewItem>();

        for (int index = 0; index < treeViewItem.Items.Count; index++)
        {
            TreeViewItem item = (TreeViewItem)treeViewItem.ItemContainerGenerator.ContainerFromIndex(index);
            if (item != null)
            {
                returnItems.Add(item);
                if (includeCollapsedItems || item.IsExpanded)
                {
                    returnItems.AddRange(GetTreeViewItemItems(item, includeCollapsedItems));
                }
            }
        }

        return returnItems;
    }

    #endregion
}
}
1
Ignacio Soler Garcia