DataTemplateに使用されているコントロールの操作から、どのデータが操作されたのか取得する方法

Question

例えば次のようなDataTemplateにおいて
CheckBoxをチェックされたタイミングで、どのLabel(TestDataインスタンス)がチェックされたのか
コード側に通知してくれるようなイベントを作れないかと模索しています。

<DataTemplate DataType="TestData">
    <StackPanel Orientation="Horizontal">
        <CheckBox IsChecked="{Binding Path=IsChecked}" />
        <TextBlock Text="{Binding Path=Label}" />
    </StackPanel>
</DataTemplate>

添付イベントを使ってみたりと四苦八苦してみたのですがうまい方法が思いつきませんでした。
何か良い方法をご存じの方がいらっしゃいましたらご教示願います。

以下にもう少し具体的なソースコードを記します。

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:t="clr-namespace:TestAssembly"
    Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.Resources>
            <HierarchicalDataTemplate x:Key="TreeViewItemDataTemplate" DataType="{x:Type t:TreeViewItemData}" ItemsSource="{Binding Path=Items}">
                <StackPanel Orientation="Horizontal">
                    <CheckBox VerticalAlignment="Center" IsChecked="{Binding Path=IsChecked}" Focusable="False" />
                    <TextBlock  VerticalAlignment="Center" Margin="3,0,0,0" Text="{Binding Path=Label}" />
                </StackPanel>
            </HierarchicalDataTemplate>
        </Grid.Resources>
        <TreeView ItemsSource="{Binding Path=Items}" ItemTemplate="{StaticResource TreeViewItemDataTemplate}" />
    </Grid>
</Window>

Class MainWindow 

    Private Sub MainWindow_Initialized(sender As Object, e As System.EventArgs) Handles Me.Initialized

        Dim rootItem As TreeViewItemData = New TreeViewItemData
        Dim item1 As TreeViewItemData = New TreeViewItemData("項目１")
        Dim item1_1 As TreeViewItemData = New TreeViewItemData("項目１－１")
        Dim item1_2 As TreeViewItemData = New TreeViewItemData("項目１－２")
        Dim item1_3 As TreeViewItemData = New TreeViewItemData("項目１－３")
        Dim item2 As TreeViewItemData = New TreeViewItemData("項目２")
        Dim item2_1 As TreeViewItemData = New TreeViewItemData("項目２－１")
        Dim item2_2 As TreeViewItemData = New TreeViewItemData("項目２－２")
        Dim item2_1_1 As TreeViewItemData = New TreeViewItemData("項目２－１－１")

        item1.Items.Add(item1_1)
        item1.Items.Add(item1_2)
        item1.Items.Add(item1_3)

        item2_1.Items.Add(item2_1_1)

        item2.Items.Add(item2_1)
        item2.Items.Add(item2_2)

        rootItem.Items.Add(item1)
        rootItem.Items.Add(item2)

        Me.DataContext = rootItem
    End Sub
End Class

Imports System.Collections.ObjectModel

Public Class TreeViewItemData
    Inherits DependencyObject

    Public Shared ReadOnly IsCheckedProperty As DependencyProperty = DependencyProperty.Register("IsChecked", GetType(Boolean), GetType(TreeViewItemData))
    Public Shared ReadOnly LabelProperty As DependencyProperty = DependencyProperty.Register("Label", GetType(String), GetType(TreeViewItemData))
    Private _items As ObservableCollection(Of TreeViewItemData) = New ObservableCollection(Of TreeViewItemData)

    Public Sub New()

    End Sub

    Public Sub New(ByVal label As String)
        Me.Label = label
    End Sub

    Public Property IsChecked As Boolean
        Get
            Return GetValue(IsCheckedProperty)
        End Get
        Set(value As Boolean)
            SetValue(IsCheckedProperty, value)
        End Set
    End Property
    Public Property Label As String
        Get
            Return GetValue(LabelProperty)
        End Get
        Set(value As String)
            SetValue(LabelProperty, value)
        End Set
    End Property
    Public ReadOnly Property Items As ObservableCollection(Of TreeViewItemData)
        Get
            Return _items
        End Get
    End Property
End Class

↑実行結果

上記のようなツリービューにおいて
「項目１－１」のチェックボックスをチェックされたタイミングで
「項目１－１」がチェックされたということをコード側で拾いたいのです。

※可能であれば
Private Sub TreeViewItemData_Checked(sender As Object, e As RoutedEventArgs)
で、sender、あるいはe.OriginalSourceの型がTreeViewItemData型のようなイメージで…

添付イベントで<TreeView CheckBox.Checked="～" />のようにすればチェックイベントを拾うことはできるのですが（この場合うまくやらないとTreeViewItemのToggleButtonのCheckedイベントも拾いますが）、肝心のどのTreeViewItemDataインスタンスがチェックされたのかということが分かりません。。。

開発環境
VS2010
実行環境
.NET4.0

以上、よろしくお願い致します。

Answer 1

選択に使用するCheckBoxに添付プロパティで目印を設定してやれば間違えることないと思いますけどね。

それでも選択した要素を知るためのイベントがほしいなら、ToggleButton.Checkedイベントを捕まえて、選択されたということを通知するRoutedEventを新たに投げてやればできると思います。

Public Class ItemsControlChecker
    Public Delegate Sub ItemCheckedRoutedEventHandler(ByVal sender As Object, ByVal e As ItemCheckedRoutedEventArgs)

    ''' <summary>>ItemsControlの要素で、要素のチェックがあった時に発生するイベント</summary>
    Public Shared ReadOnly ItemCheckedEvent As RoutedEvent = _
                      EventManager.RegisterRoutedEvent("ItemChecked", _
                      RoutingStrategy.Bubble, _
                      GetType(ItemCheckedRoutedEventHandler), GetType(ItemsControlChecker))

    Public Shared Sub AddItemCheckedHandler(ByVal d As DependencyObject, ByVal handler As ItemCheckedRoutedEventHandler)
        Dim uie As UIElement = TryCast(d, UIElement)
        If uie IsNot Nothing Then
            uie.AddHandler(ItemCheckedEvent, handler)
        End If
    End Sub
    Public Shared Sub RemoveItemCheckedHandler(ByVal d As DependencyObject, ByVal handler As ItemCheckedRoutedEventHandler)
        Dim uie As UIElement = TryCast(d, UIElement)
        If uie IsNot Nothing Then
            uie.RemoveHandler(ItemCheckedEvent, handler)
        End If
    End Sub

    Public Shared Function GetIsItemChecker(ByVal element As DependencyObject) As Boolean
        Return element.GetValue(IsItemCheckerProperty)
    End Function

    Public Shared Sub SetIsItemChecker(ByVal element As DependencyObject, ByVal value As Boolean)
        element.SetValue(IsItemCheckerProperty, value)
    End Sub


    ''' <summary>ItemsControlの要素でこの添付プロパティがTrueのCheckBoxでItemCheckedRoutedEventが発生する</summary>
    Public Shared ReadOnly IsItemCheckerProperty As  _
                           DependencyProperty = DependencyProperty.RegisterAttached("IsItemChecker", _
                           GetType(Boolean), GetType(ItemsControlChecker), _
                           New FrameworkPropertyMetadata(False, AddressOf PropertyChangedCallback))

    Public Shared Sub PropertyChangedCallback(d As System.Windows.DependencyObject, e As System.Windows.DependencyPropertyChangedEventArgs)
        Dim uie As UIElement = TryCast(d, UIElement)
        If (DirectCast(e.NewValue, Boolean)) Then
            uie.AddHandler(Primitives.ToggleButton.CheckedEvent, New RoutedEventHandler(AddressOf Checked))
        Else
            uie.RemoveHandler(Primitives.ToggleButton.CheckedEvent, New RoutedEventHandler(AddressOf Checked))
        End If
    End Sub

    Private Shared Sub Checked(ByVal sender As Object, ByVal e As RoutedEventArgs)
        If (sender Is e.OriginalSource) Then
            e.Handled = True
            Dim uie As UIElement = TryCast(sender, UIElement)
            uie.RaiseEvent(New ItemCheckedRoutedEventArgs(uie, uie.GetValue(FrameworkElement.DataContextProperty)))
        End If
    End Sub
End Class

Public Class ItemCheckedRoutedEventArgs
    Inherits System.Windows.RoutedEventArgs
    Public Sub New(ByVal source As Object, ByVal datacontext As Object)
        MyBase.New(ItemsControlChecker.ItemCheckedEvent, source)
        Me.CheckedItemData = datacontext
    End Sub
    Public Property CheckedItemData As Object
End Class

<Grid>
    <Grid.Resources>
        <HierarchicalDataTemplate x:Key="TreeViewItemDataTemplate" DataType="{x:Type app:TreeViewItemData}" ItemsSource="{Binding Path=Items}">
            <StackPanel Orientation="Horizontal">
                <CheckBox VerticalAlignment="Center" IsChecked="{Binding Path=IsChecked}" Focusable="False" 
                        app:ItemsControlChecker.IsItemChecker="true"  />
                <CheckBox Content="Dummy" />
                <TextBlock  VerticalAlignment="Center" Margin="3,0,0,0" Text="{Binding Path=Label}" />
            </StackPanel>
        </HierarchicalDataTemplate>
    </Grid.Resources>

    <TreeView ItemsSource="{Binding Path=Items}" ItemTemplate="{StaticResource TreeViewItemDataTemplate}" 
        app:ItemsControlChecker.ItemChecked="treeview_ItemChecked"/>
</Grid>

#自作添付イベントはエラーが表示されっぱなしになるのがなぁ

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個別に明示されていない限りgekkaがフォーラムに投稿したコードにはフォーラム使用条件に基づき「MICROSOFT LIMITED PUBLIC LICENSE」が適用されます。(かなり自由に使ってOK!)

Answer 2

コードビハインドにベタ書きで良いなら、CheckBox.Checkedイベントを拾ってsender（中身はCheckBox）からDataContextを取ってくれば良いだけのような気がしますが・・・
（添付イベントでも同様の方法で特定できるはず）

あるいはTreeViewItemData内でイベントを拾いたいなら、RelayCommandというクラスを作って、BlendSDKのCallMethodBehaviorと組み合わせるという手段もあります。

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:t="clr-namespace:TestAssembly"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    xmlns:core="clr-namespace:Microsoft.Expression.Interactivity.Core;assembly=Microsoft.Expression.Interactions"
    Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.Resources>
            <HierarchicalDataTemplate x:Key="TreeViewItemDataTemplate" DataType="{x:Type t:TreeViewItemData}" ItemsSource="{Binding Path=Items}">
                <StackPanel Orientation="Horizontal">
                    <!--※ベタ書きの場合。一応参考までに-->
                    <!--<CheckBox VerticalAlignment="Center" IsChecked="{Binding Path=IsChecked}" Focusable="False" Checked="CheckBox_Checked"/>-->
                    
                    <CheckBox VerticalAlignment="Center" IsChecked="{Binding Path=IsChecked}" Focusable="False" >
                        <i:Interaction.Triggers>
                            <i:EventTrigger EventName="Checked">
                                <core:CallMethodAction TargetObject="{Binding}" MethodName="OnChecked"/>
                            </i:EventTrigger>
                        </i:Interaction.Triggers>
                    </CheckBox>
                    <TextBlock  VerticalAlignment="Center" Margin="3,0,0,0" Text="{Binding Path=Label}" />
                </StackPanel>
            </HierarchicalDataTemplate>
        </Grid.Resources>
        <TreeView ItemsSource="{Binding Path=Items}" ItemTemplate="{StaticResource TreeViewItemDataTemplate}" />
    </Grid>
</Window>

Class MainWindow 

    Private Sub MainWindow_Initialized(sender As Object, e As System.EventArgs) Handles Me.Initialized

        Dim rootItem As TreeViewItemData = New TreeViewItemData
        Dim item1 As TreeViewItemData = New TreeViewItemData("項目１")
        Dim item1_1 As TreeViewItemData = New TreeViewItemData("項目１－１")
        Dim item1_2 As TreeViewItemData = New TreeViewItemData("項目１－２")
        Dim item1_3 As TreeViewItemData = New TreeViewItemData("項目１－３")
        Dim item2 As TreeViewItemData = New TreeViewItemData("項目２")
        Dim item2_1 As TreeViewItemData = New TreeViewItemData("項目２－１")
        Dim item2_2 As TreeViewItemData = New TreeViewItemData("項目２－２")
        Dim item2_1_1 As TreeViewItemData = New TreeViewItemData("項目２－１－１")

        item1.Items.Add(item1_1)
        item1.Items.Add(item1_2)
        item1.Items.Add(item1_3)

        item2_1.Items.Add(item2_1_1)

        item2.Items.Add(item2_1)
        item2.Items.Add(item2_2)

        rootItem.Items.Add(item1)
        rootItem.Items.Add(item2)

        Me.DataContext = rootItem
    End Sub

    '※ベタ書きの場合はここが呼ばれる。
    Private Sub CheckBox_Checked(sender As System.Object, e As System.Windows.RoutedEventArgs)
        Dim checkBox As CheckBox = CType(sender, CheckBox)
        Dim item As TreeViewItemData = checkBox.DataContext
        MessageBox.Show(item.Label)
    End Sub

End Class

Imports System.Collections.ObjectModel

Public Class TreeViewItemData
    Inherits DependencyObject

    Public Shared ReadOnly IsCheckedProperty As DependencyProperty = DependencyProperty.Register("IsChecked", GetType(Boolean), GetType(TreeViewItemData))
    Public Shared ReadOnly LabelProperty As DependencyProperty = DependencyProperty.Register("Label", GetType(String), GetType(TreeViewItemData))
    Private _items As ObservableCollection(Of TreeViewItemData) = New ObservableCollection(Of TreeViewItemData)

    Public Sub New()

    End Sub

    Public Sub New(ByVal label As String)
        Me.Label = label
    End Sub

    Public Property IsChecked As Boolean
        Get
            Return GetValue(IsCheckedProperty)
        End Get
        Set(value As Boolean)
            SetValue(IsCheckedProperty, value)
        End Set
    End Property
    Public Property Label As String
        Get
            Return GetValue(LabelProperty)
        End Get
        Set(value As String)
            SetValue(LabelProperty, value)
        End Set
    End Property
    Public ReadOnly Property Items As ObservableCollection(Of TreeViewItemData)
        Get
            Return _items
        End Get
    End Property

    Public Sub OnChecked(sender As System.Object, e As System.Windows.RoutedEventArgs)
        MessageBox.Show(Me.Label)
    End Sub
End Class

Public Class RelayCommand
    Implements ICommand

    Private _canExecuteAction As Func(Of Object, Boolean)
    Private _executeAction As Action(Of Object)

    Public Sub New(ByVal executeAction As Action(Of Object),
                   ByVal canExecuteAction As Func(Of Object, Boolean))
        Me._executeAction = executeAction
        Me._canExecuteAction = canExecuteAction
    End Sub

    Public Function CanExecute(ByVal parameter As Object) As Boolean _
                                                        Implements ICommand.CanExecute
        Return _canExecuteAction(parameter)
    End Function

    Public Event CanExecuteChanged(ByVal sender As Object, ByVal e As System.EventArgs) _
                                                        Implements ICommand.CanExecuteChanged

    Public Sub Execute(ByVal parameter As Object) Implements ICommand.Execute
        _executeAction(parameter)
    End Sub

End Class

コードを実行するにはBlendSDKをインストールしてMicrosoft.Expression.InteractionsとSystem.Windows.Interactivityへの参照を追加して下さい。
RelayCommandの詳細については　http://msdn.microsoft.com/ja-jp/magazine/dd419663.aspx　に詳しいことが載ってます。
あと、コードビハインドにベタ書きの場合のコードもコメントアウトして含まれてますので、そっちで良ければそのほうが簡単です。

Answer 3

私もみっとさんと同じで、Microsoft.Expression.InteractionsとSystem.Windows.Interactivityを使うと思います。以下、TriggerActionクラスを継承し、RelayCommandによりハンドラを起動しています。

<Window x:Class="DataTemplateCheckBox"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
	xmlns:t="clr-namespace:test2010wpfvb"
	xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    xmlns:core="clr-namespace:Microsoft.Expression.Interactivity.Core;assembly=Microsoft.Expression.Interactions"
	Title="DataTemplateCheckBox" Height="300" Width="300">
    
	<Grid Name="Grid1">
		<Grid.Resources>
			<HierarchicalDataTemplate x:Key="TreeViewItemDataTemplate" DataType="{x:Type t:TreeViewItemData}" ItemsSource="{Binding Items}">
				<StackPanel Orientation="Horizontal">
					<CheckBox VerticalAlignment="Center" IsChecked="{Binding Path=IsChecked}" Focusable="False">
						<i:Interaction.Triggers>
							<i:EventTrigger EventName="Checked">
								<t:MyCommandAction Command="{Binding DataContext.CheckBoxCheckedCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, Mode=OneWay}"
												   CommandParameter="{Binding }" />
							</i:EventTrigger>
						</i:Interaction.Triggers>
					</CheckBox>
					<TextBlock  VerticalAlignment="Center" Margin="3,0,0,0" Text="{Binding Path=Label}" />
				</StackPanel>
			</HierarchicalDataTemplate>
		</Grid.Resources>
		<TreeView ItemsSource="{Binding データ.Items}" ItemTemplate="{StaticResource TreeViewItemDataTemplate}" />
	</Grid>
	
</Window>

Imports System.Collections.ObjectModel
Imports System.Windows.Interactivity
Public Class DataTemplateCheckBox
    Private Sub DataTemplateCheckBox_Initialized(sender As System.Object, e As System.EventArgs) Handles MyBase.Initialized
        Dim rootItem As TreeViewItemData = New TreeViewItemData
        Dim item1 As TreeViewItemData = New TreeViewItemData("項目１")
        Dim item1_1 As TreeViewItemData = New TreeViewItemData("項目１－１")
        Dim item1_2 As TreeViewItemData = New TreeViewItemData("項目１－２")
        Dim item1_3 As TreeViewItemData = New TreeViewItemData("項目１－３")
        Dim item2 As TreeViewItemData = New TreeViewItemData("項目２")
        Dim item2_1 As TreeViewItemData = New TreeViewItemData("項目２－１")
        Dim item2_2 As TreeViewItemData = New TreeViewItemData("項目２－２")
        Dim item2_1_1 As TreeViewItemData = New TreeViewItemData("項目２－１－１")
        item1.Items.Add(item1_1)
        item1.Items.Add(item1_2)
        item1.Items.Add(item1_3)
        item2_1.Items.Add(item2_1_1)
        item2.Items.Add(item2_1)
        item2.Items.Add(item2_2)
        rootItem.Items.Add(item1)
        rootItem.Items.Add(item2)
        Me.データ = rootItem
        'コマンドの設定
        CheckBoxCheckedCommand = New RelayCommand(AddressOf CheckedChanged)
        Me.DataContext = Me
    End Sub
    'プロパティ
    Public Property データ As TreeViewItemData
    'コマンドの定義
    Public Property CheckBoxCheckedCommand As ICommand
    'コマンドハンドラ
    Private Sub CheckedChanged(ByVal obj As Object)
        System.Diagnostics.Debug.WriteLine(DirectCast(obj, TreeViewItemData).Label)
    End Sub
End Class

Public Class TreeViewItemData
    Inherits DependencyObject
    Public Shared ReadOnly IsCheckedProperty As DependencyProperty = DependencyProperty.Register("IsChecked", GetType(Boolean), GetType(TreeViewItemData))
    Public Shared ReadOnly LabelProperty As DependencyProperty = DependencyProperty.Register("Label", GetType(String), GetType(TreeViewItemData))
    Private _items As ObservableCollection(Of TreeViewItemData) = New ObservableCollection(Of TreeViewItemData)
    Public Sub New()
    End Sub
    Public Sub New(ByVal label As String)
        Me.Label = label
    End Sub
    Public Property IsChecked As Boolean
        Get
            Return GetValue(IsCheckedProperty)
        End Get
        Set(value As Boolean)
            SetValue(IsCheckedProperty, value)
        End Set
    End Property
    Public Property Label As String
        Get
            Return GetValue(LabelProperty)
        End Get
        Set(value As String)
            SetValue(LabelProperty, value)
        End Set
    End Property
    Public ReadOnly Property Items As ObservableCollection(Of TreeViewItemData)
        Get
            Return _items
        End Get
    End Property
End Class

Public Class MyCommandAction
    Inherits TriggerAction(Of FrameworkElement)
    Public Shared ReadOnly CommandProperty As DependencyProperty = DependencyProperty.Register("Command", GetType(ICommand), GetType(MyCommandAction), New UIPropertyMetadata())
    Public Property Command() As ICommand
        Get
            Return DirectCast(GetValue(CommandProperty), ICommand)
        End Get
        Set(value As ICommand)
            SetValue(CommandProperty, value)
        End Set
    End Property
    Public Shared ReadOnly CommandParameterProperty As DependencyProperty = DependencyProperty.Register("CommandParameter", GetType(Object), GetType(MyCommandAction), New UIPropertyMetadata())
    Public Property CommandParameter() As Object
        Get
            Return DirectCast(GetValue(CommandParameterProperty), Object)
        End Get
        Set(value As Object)
            SetValue(CommandParameterProperty, value)
        End Set
    End Property
    Protected Overrides Sub Invoke(obj As Object)
        Command.Execute(CommandParameter)
    End Sub
End Class

Imports System.ComponentModel
Imports System.Windows.Input
Public Class RelayCommand
    Implements ICommand
    Private _canExecuteAction As Func(Of Object, Boolean)
    Private _executeAction As Action(Of Object)
    Public Sub New(ByVal executeAction As Action(Of Object),
                   ByVal canExecuteAction As Func(Of Object, Boolean))
        Me._executeAction = executeAction
        Me._canExecuteAction = canExecuteAction
    End Sub
    Public Sub New(ByVal executeAction As Action(Of Object))
        Me._executeAction = executeAction
        _canExecuteAction = Function()
                                Return True
                            End Function
    End Sub
    Public Function CanExecute(ByVal parameter As Object) As Boolean _
                                                        Implements ICommand.CanExecute
        Return _canExecuteAction(parameter)
    End Function
    Public Event CanExecuteChanged(ByVal sender As Object, ByVal e As System.EventArgs) _
                                                        Implements ICommand.CanExecuteChanged
    Public Sub Execute(ByVal parameter As Object) Implements ICommand.Execute
        _executeAction(parameter)
    End Sub
End Class

＃う～ん、空白行がねぐられたり、うまくコードが載っけられないなぁ・・・・

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★良い回答には回答済みマークを付けよう！ わんくま同盟 MVP - Visual C# http://d.hatena.ne.jp/trapemiya/

Answer 4

にーもにっくさん、こんにちは。
返信下さった皆さまの投稿が参考になったと思われますので、勝手ながら私の方で回答マークを付けさせて頂きました。

参考になった投稿には、質問者が回答マークを付けることができます。またマークは にーもにっくさんが後から外すことも可能です。
他の方が後から閲覧した際参考にして頂くためにも、ぜひ回答をマークして頂くようお勧めいたします。

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ひらぽん http://d.hatena.ne.jp/hilapon/