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HierarchicalDataTemplate.ItemContainerStyleSelector Property

Gets or sets custom style-selection logic for a style that can be applied to each item container.

Namespace:  System.Windows
Assembly:  PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation

public StyleSelector ItemContainerStyleSelector { get; set; }
<object>
  <object.ItemContainerStyleSelector>
    <StyleSelector .../>
  </object.ItemContainerStyleSelector>
</object>

Property Value

Type: System.Windows.Controls.StyleSelector
A StyleSelector that chooses which style to use as the ItemContainerStyle. The default is null.

You use the ItemContainerStyle property to set a style to affect the appearance of the elements that contain the data items. For example, for TreeView, the generated containers are TreeViewItem controls; for Menu, they are MenuItem controls. If you have more than one style defined and need to supply logic to choose which one to apply, then you use the ItemContainerStyleSelector property instead of the ItemContainerStyle property. Note that this property is ignored if the ItemContainerStyle property is set.

The following example creates a TreeView that uses the ItemContainerStyle of a HierarchicalDataTemplate to choose between two styles for items in the second level of the TreeView.


<StackPanel Name="sp1" x:FieldModifier="public">
  <StackPanel.Resources>
    <src:TreeViewData x:Key="dataItems"/>

    <Style x:Key="TreeViewItemStyle1"  TargetType="TreeViewItem">
      <Setter Property="Foreground" Value="Navy"/>
      <Setter Property="FontStyle" Value="Italic"/>
    </Style>

    <Style x:Key="TreeViewItemStyle2"  TargetType="TreeViewItem">
      <Setter Property="Foreground" Value="Green"/>
      <Setter Property="FontWeight" Value="Bold"/>
    </Style>

    <src:TreeViewItemStyleSelector x:Key="tviSelector"/>

    <HierarchicalDataTemplate DataType="{x:Type src:ItemsForTreeView}"
                              ItemsSource="{Binding Path=SecondLevelItems}"
                              ItemContainerStyleSelector="{StaticResource tviSelector}">

      <!--Display the TopLevelName property in the first level.-->
      <TextBlock Text="{Binding Path=TopLevelName}"/>

      <!--Display each string in the SecondLevelItems property in
          the second level.-->
      <HierarchicalDataTemplate.ItemTemplate>
          <DataTemplate>
              <TextBlock Text="{Binding}"/>
          </DataTemplate>
      </HierarchicalDataTemplate.ItemTemplate>

    </HierarchicalDataTemplate>
  </StackPanel.Resources>

  <TreeView Height="200" ItemsSource="{Binding Source={StaticResource dataItems}}"
            VirtualizingStackPanel.IsVirtualizing="True">
    <TreeView.ItemContainerStyle>

      <!--Expand each TreeViewItem in the first level.-->
      <Style TargetType="TreeViewItem">
        <Setter Property="IsExpanded" Value="True"/>
      </Style>
    </TreeView.ItemContainerStyle>
  </TreeView>
</StackPanel>


The following example shows the StyleSelector that is used in the previous example.


public class TreeViewItemStyleSelector : StyleSelector
{
    public override Style SelectStyle(object item, DependencyObject container)
    {
        string itemString = item as string;

        string[] strings = itemString.Split(null);
        int value;

        if (!Int32.TryParse(strings[strings.Length - 1], out value))
        {
            return null;
        }

        StackPanel sp = ((Window1) Application.Current.MainWindow).sp1;

        if (value < 5)
        {
            return sp.FindResource("TreeViewItemStyle1") as Style;
        }
        else
        {
            return sp.FindResource("TreeViewItemStyle2") as Style;
        }

    }
}


The following example creates the data that is used in the previous example.


public class TreeViewData : ObservableCollection<ItemsForTreeView>
{

    public TreeViewData()
    {
        for (int i = 0; i < 100; ++i)
        {
            ItemsForTreeView item = new ItemsForTreeView();
            item.TopLevelName = "item " + i.ToString();
            Add(item);
        }
    }
}


public class ItemsForTreeView
{
    public string TopLevelName { get; set; }
    private ObservableCollection<string> level2Items;

    public ObservableCollection<string> SecondLevelItems
    {
        get 
        {
            if (level2Items == null)
            {
                level2Items = new ObservableCollection<string>();
            }
            return level2Items;
        }
    }

    public ItemsForTreeView()
    {
        for (int i = 0; i < 10; ++i)
        {
            SecondLevelItems.Add("Second Level " + i.ToString());
        }
    }
}


.NET Framework

Supported in: 4, 3.5 SP1, 3.0 SP2

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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