WPF TreeView Selection

Question

3.00/5 (2 votes)

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Hi!

I would like to create a treeview, that behaves the following way: If I click on an item in the treeview, the item will be selected. This is the default behaviour, if I use a treeview with TextBlocks. But if I use TextBoxes instead, the behaviour is lost. The item will only be selected, if I click on the border of the item. I use the following code to repair this:

XML

<TreeView.Resources>
    <Style TargetType="TreeViewItem">
        <Style.Triggers>
            <Trigger Property="FrameworkElement.IsKeyboardFocusWithin" Value="True">
                <Setter Property="IsSelected" Value="True" />
            </Trigger>
        </Style.Triggers>
    </Style>
</TreeView.Resources>

It works quite fine, but if I select a child item before the parent, the parent will be selected, and if I select a parent before its child items and I select the parent again, the parent won't be selected. I don't really understand why. Could someone give a solution to this problem?

Posted 27-Jun-12 7:24am

Csaba Czine

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Comments

Sergey Alexandrovich Kryukov 27-Jun-12 13:56pm

Yes, this is a problem; I voted 5 for the question.
--SA

3 solutions

Solution 1

I would be interested is seeing a full example. I might suggest trying code behind instead. Since this is a View issue that should be fine, keeping with the MVVM pattern. Voted 5 for question.

Posted 28-Jun-12 6:47am

Clifford Nelson

Comments

Clifford Nelson 29-Jun-12 12:08pm

Whoever gave me the one, my code behind was obviously the solution. If I had had more code, I would have gotten further, like the solution.

Solution 3

Thank you for the hint and the code. I added finally a handler to the GotKeyboardFocus event of the TextBox the following way, and it works fine.

private void TextBox_GotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
    DependencyObject item = sender as DependencyObject;

    while (item != null && !(item is TreeViewItem))
    {
        item = VisualTreeHelper.GetParent(item);
    }

    if (item != null)
    {
        ((TreeViewItem)item).IsSelected = true;
    }
}

Posted 29-Jun-12 0:36am

Csaba Czine

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User 2179238 · Accepted Answer · 2012-06-28T23:37:00

Thanks for a nice question. I think there could be several solutions for that. One solution could be to find the Visual Parent in the Code behind and then select the treeViewitem. So What i have done is given below,

The XAML Code,

C#

<StackPanel>
       <TreeView>
           <TreeView.Resources>
               <Style TargetType="TreeViewItem">
                   <Setter Property="Padding" Value="5"/>
                   <Setter Property="HeaderTemplate">
                       <Setter.Value>
                           <DataTemplate>
                               <TextBox Text="{Binding Mode=OneWay}"  IsKeyboardFocusedChanged="TextBox_IsKeyboardFocusedChanged"/>
                           </DataTemplate>
                       </Setter.Value>
                   </Setter>
                   <!--<Style.Triggers>
                       <Trigger Property="IsKeyboardFocusWithin" Value="True">
                           <Setter Property="IsSelected" Value="True"/>
                       </Trigger>
                   </Style.Triggers>-->
               </Style>
           </TreeView.Resources>
           <TreeViewItem Header="One">
               <TreeViewItem Header="ChildOne"/>
           </TreeViewItem>
           <TreeViewItem Header="One">
               <TreeViewItem Header="ChildOne"/>
           </TreeViewItem>
           <TreeViewItem Header="One">
               <TreeViewItem Header="ChildOne"/>
           </TreeViewItem>
       </TreeView>
       <TreeView>
           <TreeViewItem Header="One">
               <TreeViewItem Header="ChildOne"/>
           </TreeViewItem>
           <TreeViewItem Header="One">
               <TreeViewItem Header="ChildOne"/>
           </TreeViewItem>
           <TreeViewItem Header="One">
               <TreeViewItem Header="ChildOne"/>
           </TreeViewItem>
       </TreeView>
   </StackPanel>

And in the code behind you need to write some code,

C#

private void TextBox_IsKeyboardFocusedChanged(object sender, DependencyPropertyChangedEventArgs e)
       {
           if (Convert.ToBoolean(e.NewValue) == true)
           {
               var v = FindVisualParent<TreeViewItem>(sender as UIElement);
               v.IsSelected = true;
           }

       }

       public static T FindVisualParent<T>(UIElement element) where T : UIElement
       {
           UIElement parent = element; while (parent != null)
           {
               T correctlyTyped = parent as T; if (correctlyTyped != null)
               {
                   return correctlyTyped;
               }
               parent = VisualTreeHelper.GetParent(parent) as UIElement;
           } return null;
       }

That's all. Enjoy it.