PopulatingEventArgs Class
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Provides data for the AutoCompleteBox.Populating event.
Inheritance Hierarchy
System.Object
System.EventArgs
System.Windows.RoutedEventArgs
System.Windows.Controls.PopulatingEventArgs
Namespace: System.Windows.Controls
Assembly: System.Windows.Controls.Input (in System.Windows.Controls.Input.dll)
Syntax
'Declaration
Public Class PopulatingEventArgs _
Inherits RoutedEventArgs
public class PopulatingEventArgs : RoutedEventArgs
The PopulatingEventArgs type exposes the following members.
Constructors
| Name | Description | |
|---|---|---|
.gif "Public method") |
PopulatingEventArgs | Initializes a new instance of the PopulatingEventArgs class. |
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Properties
| Name | Description | |
|---|---|---|
.gif "Public property") |
Cancel | Gets or sets a value that indicates whether the Populating event should be canceled. |
|
OriginalSource | Gets a reference to the object that raised the event. (Inherited from RoutedEventArgs.) |
|
Parameter | Gets the text that is used to determine which items to display in the AutoCompleteBox control. |
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Methods
| Name | Description | |
|---|---|---|
|
Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
.gif "Protected method") |
Finalize | Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.) |
|
GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
|
GetType | Gets the Type of the current instance. (Inherited from Object.) |
|
MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
|
ToString | Returns a string that represents the current object. (Inherited from Object.) |
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Examples
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()
InitializeComponent()
' Add some topics to the collection.
Dim UsingControls As New Topic("Using Controls and Dialog Boxes", _
Guid.NewGuid())
UsingControls.ChildTopics.Add(New Topic("Getting Started with Controls", _
Guid.NewGuid()))
Dim DataGridTopic As New Topic("DataGrid", Guid.NewGuid())
DataGridTopic.ChildTopics.Add( _
New Topic("Default Keyboard and Mouse Behavior in the DataGrid Control", _
Guid.NewGuid()))
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", _
Guid.NewGuid()))
UsingControls.ChildTopics.Add(DataGridTopic)
UsingControls.ChildTopics.Add(New Topic("Ink Presenter", Guid.NewGuid()))
Topics.Add(UsingControls)
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)), _
TreeViewItem)
If childItem IsNot Nothing Then
ExpandAllTreeViewItems(childItem)
End If
Next
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})
Else
For i As Integer = 0 To currentTreeViewItem.Items.Count - 1
Dim child As TreeViewItem = _
DirectCast(currentTreeViewItem.ItemContainerGenerator.ContainerFromIndex(i), _
TreeViewItem)
ExpandAllTreeViewItems(child)
Next
End If
End Sub
' Simple business object.
Public Class Topic
Private _Title As String
Public Property Title() As String
Get
Return _Title
End Get
Set(ByVal value As String)
_Title = value
End Set
End Property
Private _Id As Guid
Public Property Id() As Guid
Get
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)
Get
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)
Me.New()
Title = title__1
Id = idValue
End Sub
End Class
End Class
public partial class MainPage : UserControl
{
// Create the topics collection.
static public ObservableCollection<Topic> Topics =
new ObservableCollection<Topic>();
public MainPage()
{
InitializeComponent();
// Add some topics to the collection.
Topic UsingControls = new Topic("Using Controls and Dialog Boxes", Guid.NewGuid());
UsingControls.ChildTopics.Add(new Topic("Getting Started with Controls", Guid.NewGuid()));
Topic DataGridTopic = new Topic("DataGrid", Guid.NewGuid());
DataGridTopic.ChildTopics.Add(
new Topic("Default Keyboard and Mouse Behavior in the DataGrid Control",
Guid.NewGuid()));
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",
Guid.NewGuid()));
UsingControls.ChildTopics.Add(DataGridTopic);
UsingControls.ChildTopics.Add(new Topic("Ink Presenter", Guid.NewGuid()));
Topics.Add(UsingControls);
myTreeView.DataContext = Topics;
}
void myTreeView_MouseEnter(object sender, MouseEventArgs e)
{
ExpandAll(sender, e);
}
// Method to expand all the treeview children.
private void ExpandAll(object sender, RoutedEventArgs e)
{
for (int i = 0; i < myTreeView.Items.Count; i++)
{
TreeViewItem childItem =
myTreeView.ItemContainerGenerator.ContainerFromItem(myTreeView.Items[i])
as TreeViewItem;
if (childItem != null)
ExpandAllTreeViewItems(childItem);
}
}
// 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.
public delegate void ExpandChildren(TreeViewItem currentTreeViewItem);
// Exapand all the children of the current treeview item.
private void ExpandAllTreeViewItems(TreeViewItem currentTreeViewItem)
{
// If the current node is not expanded, call the expansion asynchronously
// to ensure the items are instantiated before expansion.
if (!currentTreeViewItem.IsExpanded)
{
currentTreeViewItem.IsExpanded = true;
// Asynchronous call to expand the children.
currentTreeViewItem.Dispatcher.BeginInvoke(new
ExpandChildren(ExpandAllTreeViewItems),
new object[] { currentTreeViewItem });
// Alternatively, you could make the call to ExpandAllTreeViewItems
// using lambda syntax.
// currentTreeViewItem.Dispatcher.BeginInvoke(() =>
// ExpandAllTreeViewItems(currentTreeViewItem));
}
else
{
for (int i = 0; i < currentTreeViewItem.Items.Count; i++)
{
TreeViewItem child = (TreeViewItem)
currentTreeViewItem.ItemContainerGenerator.ContainerFromIndex(i);
ExpandAllTreeViewItems(child);
}
}
}
// Simple business object.
public class Topic
{
public string Title { get; set; }
public Guid Id { get; set; }
public ObservableCollection<Topic> ChildTopics { get; set; }
public Topic()
{
ChildTopics = new ObservableCollection<Topic>();
}
public Topic(string title, Guid idValue)
: this()
{
Title = title;
Id = idValue;
}
}
}
<StackPanel x:Name="LayoutRoot" Background="White">
<StackPanel.Resources>
<sdk:HierarchicalDataTemplate x:Key="ChildTemplate" ItemsSource="{Binding Path=ChildTopics}" >
<TextBlock FontStyle="Italic" Text="{Binding Path=Title}" />
</sdk:HierarchicalDataTemplate>
<sdk:HierarchicalDataTemplate x:Key="RootTemplate"
ItemsSource="{Binding Path=ChildTopics}"
ItemTemplate="{StaticResource ChildTemplate}">
<TextBlock Text="{Binding Path=Title}" FontWeight="Bold" />
</sdk:HierarchicalDataTemplate>
</StackPanel.Resources>
<sdk:TreeView Width="400" Height="200" ItemsSource="{Binding}"
ItemTemplate="{StaticResource RootTemplate}" x:Name="myTreeView"
MouseEnter="myTreeView_MouseEnter" />
</StackPanel>
Version Information
Silverlight
Supported in: 5, 4, 3
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.