HierarchicalDataTemplate.ItemContainerStyleSelector Property
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Gets or sets custom style-selection logic for a style that can be applied to each item container.
public:
property System::Windows::Controls::StyleSelector ^ ItemContainerStyleSelector { System::Windows::Controls::StyleSelector ^ get(); void set(System::Windows::Controls::StyleSelector ^ value); };
public System.Windows.Controls.StyleSelector ItemContainerStyleSelector { get; set; }
member this.ItemContainerStyleSelector : System.Windows.Controls.StyleSelector with get, set
Public Property ItemContainerStyleSelector As StyleSelector
A StyleSelector that chooses which style to use as the ItemContainerStyle. The default is null
.
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;
}
}
}
Public Class TreeViewItemStyleSelector
Inherits StyleSelector
Public Overloads Overrides Function SelectStyle(ByVal item As Object, ByVal container As DependencyObject) As Style
Dim itemString As String = TryCast(item, String)
Dim strings As String() = itemString.Split(Nothing)
Dim value As Integer
If Not Int32.TryParse(strings(strings.Length - 1), value) Then
Return Nothing
End If
Dim win1 As Window1 = CType(Application.Current.MainWindow, Window1)
Dim sp As StackPanel = win1.sp1
If value < 5 Then
Return TryCast(sp.FindResource("TreeViewItemStyle1"), Style)
Else
Return TryCast(sp.FindResource("TreeViewItemStyle2"), Style)
End If
End Function
End Class
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
{
level2Items ??= new ObservableCollection<string>();
return level2Items;
}
}
public ItemsForTreeView()
{
for (int i = 0; i < 10; ++i)
{
SecondLevelItems.Add("Second Level " + i.ToString());
}
}
}
Public Class TreeViewData
Inherits ObservableCollection(Of ItemsForTreeView)
Public Sub New()
For i As Integer = 0 To 99
Dim item As New ItemsForTreeView()
item.TopLevelName = "item " & i.ToString()
Add(item)
Next
End Sub
End Class
Public Class ItemsForTreeView
Private _TopLevelName As String
Public Property TopLevelName() As String
Get
Return _TopLevelName
End Get
Set(ByVal value As String)
_TopLevelName = value
End Set
End Property
Private level2Items As ObservableCollection(Of String)
Public ReadOnly Property SecondLevelItems() As ObservableCollection(Of String)
Get
If level2Items Is Nothing Then
level2Items = New ObservableCollection(Of String)()
End If
Return level2Items
End Get
End Property
Public Sub New()
For i As Integer = 0 To 9
SecondLevelItems.Add("Second Level " & i.ToString())
Next
End Sub
End Class
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.
Product | Versions |
---|---|
.NET Framework | 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
Windows Desktop | 3.0, 3.1, 5, 6, 7, 8, 9 |
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