Condividi tramite

  • Articolo

ItemContainerGenerator Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Provides mappings between the items of an ItemsControl and their container elements.

Inheritance Hierarchy

System.Object
  System.Windows.Controls.ItemContainerGenerator

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

Syntax

'Declaration
Public NotInheritable Class ItemContainerGenerator _
    Implements IRecyclingItemContainerGenerator, IItemContainerGenerator

public sealed class ItemContainerGenerator : IRecyclingItemContainerGenerator, 
    IItemContainerGenerator

The ItemContainerGenerator type exposes the following members.

Methods

  Name Description
Public methodSupported by Silverlight for Windows Phone ContainerFromIndex Returns the container for the item at the specified index within the ItemCollection.
Public methodSupported by Silverlight for Windows Phone ContainerFromItem Returns the container corresponding to the specified item.
Public methodSupported by Silverlight for Windows Phone Equals(Object) Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows Phone 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.)
Public methodSupported by Silverlight for Windows Phone GeneratorPositionFromIndex Gets the generated position of the item at the specified index.
Public methodSupported by Silverlight for Windows Phone GetHashCode Serves as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by Silverlight for Windows Phone GetType Gets the Type of the current instance. (Inherited from Object.)
Public methodSupported by Silverlight for Windows Phone IndexFromContainer Returns the index to the item that has the specified, generated container.
Public methodSupported by Silverlight for Windows Phone IndexFromGeneratorPosition Returns the index that maps to the specified GeneratorPosition.
Public methodSupported by Silverlight for Windows Phone ItemFromContainer Returns the item that corresponds to the specified, generated container.
Protected methodSupported by Silverlight for Windows Phone MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by Silverlight for Windows Phone ToString Returns a string that represents the current object. (Inherited from Object.)

Top

Events

  Name Description
Public eventSupported by Silverlight for Windows Phone ItemsChanged Occurs when the contents of the items collection changes.

Top

Explicit Interface Implementations

  Name Description
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows Phone IItemContainerGenerator.GenerateNext Returns the container element used to display the next item, and whether the container element has been newly generated (realized).
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows Phone IItemContainerGenerator.GetItemContainerGeneratorForPanel Returns the ItemContainerGenerator appropriate for use by the specified panel.
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows Phone IItemContainerGenerator.PrepareItemContainer Prepares the specified element as the container for the corresponding item.
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows Phone IItemContainerGenerator.Remove Removes one or more generated (realized) items.
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows Phone IItemContainerGenerator.RemoveAll Removes all generated (realized) items.
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows Phone IItemContainerGenerator.StartAt Prepares the generator to generate items, starting at the specified GeneratorPosition, and in the specified GeneratorDirection, and controlling whether or not to start at a generated (realized) item.
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows Phone IRecyclingItemContainerGenerator.Recycle Disassociates item containers from their data items and saves the containers so they can be reused later for other data items.

Top

Remarks

The ItemContainerGenerator class maintains associations between items controls and their item containers, such as ListBox and ListBoxItem. If a control has an associated ItemContainerGenerator, you will be able to retrieve it through a property on the control

You can use the ItemContainerGenerator to retrieve items based on their index or containers by specifying the data item. For example, if you have a data-bound TreeView, and you want to get a TreeViewItem based on its index, you can use the ContainerFromIndex method. If you want to retrieve the data item, use ItemFromContainer method.

Examples

The following example shows how to retrieve an ItemContainerGenerator for a TreeView object and use the ContainerFromIndex method.

Run this sample

Public Sub New()
    InitializeComponent()
    Dim myItems As String() = New String() {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"}
    myTreeView.DataContext = myItems
End Sub
Shared count As Integer = 1
Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim item As TreeViewItem = DirectCast(myTreeView.ItemContainerGenerator.ContainerFromIndex(3), TreeViewItem)
    item.IsExpanded = True
    If count < 5 Then
        item.Items.Add("Child " & count.ToString())
        count += 1
    End If
End Sub

public MainPage()
{
    InitializeComponent();
    string[] myItems = new string[]{"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"};
    myTreeView.DataContext = myItems;
}
static int count = 1;
private void Button_Click(object sender, RoutedEventArgs e)
{
    TreeViewItem item = (TreeViewItem)myTreeView.ItemContainerGenerator.ContainerFromIndex(3);
    item.IsExpanded = true;
    if (count < 5)
    {
        item.Items.Add("Child " + count.ToString());
        count++;
    }
}

<StackPanel x:Name="LayoutRoot" Background="White">
    <sdk:TreeView x:Name="myTreeView" Width="200" ItemsSource="{Binding}" Margin="5"/>
    <Button Content="Add Child to Item 4" Width="150" Click="Button_Click"/>
</StackPanel>

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

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.