Non Collapsible TreeViewItem

Question

I am working on a WPF project and I have a TreeView using HierarchicalDataTemplates. I have been able to establish some different levels of nodes. Everything is going well so far.

<TreeView Margin="14,14,14,14" Name="treeView" ItemsSource="{Binding Tree}"                                BorderThickness="0">
                   <TreeView.Resources>
                     <!--
                         First Level
                     -->
                     <HierarchicalDataTemplate DataType="{x:Type vm:FirstLevelViewModel}"                                                ItemsSource="{Binding Children}" >
                         <StackPanel Orientation="Horizontal" >
                         <TextBlock Text="{Binding SomeText}" FontSize="14" FontWeight="Bold" Foreground="DarkBlue"  />
                         </StackPanel>
                                                </HierarchicalDataTemplate>
                     <!--
                         Second Level
                     -->
                     <HierarchicalDataTemplate DataType="{x:Type vm:SecondLevelViewModel}"                                                ItemsSource="{Binding Children}" >
                             <CheckBox Name="checkBox" IsChecked="{Binding IsChecked}" IsEnabled="{Binding IsEnabled}">
                             <StackPanel Orientation="Horizontal">
                             <TextBlock Text="{Binding SomeText}" FontSize="14" />
                             </StackPanel>
                         </CheckBox>
                     </HierarchicalDataTemplate> . . . .  

My problem is that: I need some nodes to be non collapsible.

Is there any way to achieve that? I have been searching about it with no luck.

Answer 1

For the TreeView, you need to set up the ItemContainerStyle and then use a style something like

 <Style x:Key="TreeViewStyle" TargetType="{x:Type TreeViewItem}">
     <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
 </Style>

You can set the IsExpanded based on different criteria.  Another option would be using a Converter to set the IsExpanded property and putting your criteria in there instead. 

Hope that helps!

---

Christine A. Piffat

Answer 2

Hi

you need to set like this for treeviewitem to be expanded and toggled button to be noncollapsible

 <Style TargetType="TreeViewItem">
                <Setter Property="IsExpanded" Value="True" />
                <Setter Property="IsHitTestVisible" Value="False" />
            </Style>

so you need to set the binding for these from your property like this

<Style  TargetType="TreeViewItem">
                <Setter Property="IsExpanded" Value="{Binding ToBeExpanded}" />
                <Setter Property="IsHitTestVisible" Value="{Binding TobeToggled}" />
            </Style>