PopulatingEventArgs Class


Provides data for the AutoCompleteBox.Populating event.


Namespace:  System.Windows.Controls
Assembly:  System.Windows.Controls.Input (in System.Windows.Controls.Input.dll)

Public Class PopulatingEventArgs _
	Inherits RoutedEventArgs

The PopulatingEventArgs type exposes the following members.

Public methodPopulatingEventArgsInitializes a new instance of the PopulatingEventArgs class.

Public propertyCancelGets or sets a value that indicates whether the Populating event should be canceled.
Public propertyOriginalSourceGets a reference to the object that raised the event. (Inherited from RoutedEventArgs.)
Public propertyParameterGets the text that is used to determine which items to display in the AutoCompleteBox control.

Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)

Run this sample

The following example shows how to use the ItemContainerGenerator to expand all the nodes of a TreeView when the mouse enters the control.

Partial Public Class MainPage
    Inherits UserControl

    ' Create the topics collection. 
    Public Shared Topics As New ObservableCollection(Of Topic)()
    Public Sub New()

        ' Add some topics to the collection. 
        Dim UsingControls As New Topic("Using Controls and Dialog Boxes", _
        UsingControls.ChildTopics.Add(New Topic("Getting Started with Controls", _
        Dim DataGridTopic As New Topic("DataGrid", Guid.NewGuid())
        DataGridTopic.ChildTopics.Add( _
            New Topic("Default Keyboard and Mouse Behavior in the DataGrid Control", _
        DataGridTopic.ChildTopics.Add( _
            New Topic("How to: Add a DataGrid Control to a Page", Guid.NewGuid()))
        DataGridTopic.ChildTopics.Add( _
            New Topic("How to: Display and Configure Row Details in the DataGrid Control", _
        UsingControls.ChildTopics.Add(New Topic("Ink Presenter", Guid.NewGuid()))
        myTreeView.DataContext = Topics

    End Sub

    Private Sub myTreeView_MouseEnter(ByVal sender As Object, ByVal e As MouseEventArgs)
        ExpandAll(sender, e)
    End Sub

    Private Sub ExpandAll(ByVal sender As Object, ByVal e As RoutedEventArgs)
        For i As Integer = 0 To myTreeView.Items.Count - 1
            Dim childItem As TreeViewItem = _
                TryCast(myTreeView.ItemContainerGenerator.ContainerFromItem(myTreeView.Items(i)),  _
            If childItem IsNot Nothing Then
            End If
    End Sub

    ' Declare a delegate for the method to expand all children. 
    Public Delegate Sub ExpandChildren(ByVal currentTreeViewItem As TreeViewItem)

    '   Declare a delegate for the method to expand all children. You'll do this
    ' asynchronously to ensure the items are instatiated before they are expanded. 
    Private Sub ExpandAllTreeViewItems(ByVal currentTreeViewItem As TreeViewItem)
        If Not currentTreeViewItem.IsExpanded Then

            currentTreeViewItem.IsExpanded = True

            ' Call this method asynchronously to ensure the items are 
            ' instantiated before expansion. 
            currentTreeViewItem.Dispatcher.BeginInvoke( _
                New ExpandChildren(AddressOf ExpandAllTreeViewItems), _
                New Object() {currentTreeViewItem})

            For i As Integer = 0 To currentTreeViewItem.Items.Count - 1
                Dim child As TreeViewItem = _
                    DirectCast(currentTreeViewItem.ItemContainerGenerator.ContainerFromIndex(i),  _
        End If
    End Sub

    ' Simple business object. 
    Public Class Topic
        Private _Title As String
        Public Property Title() As String
                Return _Title
            End Get
            Set(ByVal value As String)
                _Title = value
            End Set
        End Property
        Private _Id As Guid
        Public Property Id() As Guid
                Return _Id
            End Get
            Set(ByVal value As Guid)
                _Id = value
            End Set
        End Property
        Private _ChildTopics As ObservableCollection(Of Topic)
        Public Property ChildTopics() As ObservableCollection(Of Topic)
                Return _ChildTopics
            End Get
            Set(ByVal value As ObservableCollection(Of Topic))
                _ChildTopics = value
            End Set
        End Property
        Public Sub New()
            ChildTopics = New ObservableCollection(Of Topic)()
        End Sub
        Public Sub New(ByVal title__1 As String, ByVal idValue As Guid)
            Title = title__1
            Id = idValue
        End Sub
    End Class
End Class

<StackPanel x:Name="LayoutRoot" Background="White">
        <sdk:HierarchicalDataTemplate x:Key="ChildTemplate" ItemsSource="{Binding Path=ChildTopics}"  >
            <TextBlock FontStyle="Italic" Text="{Binding Path=Title}"  />
        <sdk:HierarchicalDataTemplate x:Key="RootTemplate" 
            ItemsSource="{Binding Path=ChildTopics}" 
            ItemTemplate="{StaticResource ChildTemplate}">
            <TextBlock Text="{Binding Path=Title}" FontWeight="Bold" />
    <sdk:TreeView Width="400" Height="200" ItemsSource="{Binding}" 
        ItemTemplate="{StaticResource RootTemplate}" x:Name="myTreeView" 
        MouseEnter="myTreeView_MouseEnter" />


Supported in: 5, 4, 3

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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