c# - the level of a treeview in WPF?

Question

In a WinForms application, the level of a treeview is given by node.level
What is the corresponding command in WPF?

Answer 1

Given the Question:-

so when I click a node, how do I know which level it is? is there workaround?

Here's a possible workaround:-

If you have a reference to a Control in the Visual Tree, possibly from a Click event then you can use that control to work out which level it is in the tree view by calling a function like this, that I've used in the past.

private int FindTreeLevel(DependencyObject control)
{
  var level = -1;
  if (control != null)
  {
    var parent = VisualTreeHelper.GetParent(control);
    while (!(parent is TreeView) && (parent != null))
    {
      if (parent is TreeViewItem)
        level++;
      parent = VisualTreeHelper.GetParent(parent);
    }
  }
  return level;
}

This method will walk up the VisualTree and count how many TreeViewItem controls it finds before stopping when it finds the TreeView Control.

If you need this available in XAML, for example, a DataTrigger of a HierarchicalDataTemplate then you could package this up in to a IValueConverter class

<Window.Resources>
  <local:TreeLevelConverter x:Key="treeLevelConverter"/>

  <HierarchicalDataTemplate DataType="{x:Type local:MyType}" >
  ...
     <Grid ... >
         <TextBlock x:Name="MyControl" ... />
     ...
     </Grid>
     <HierarchicalDataTemplate.Triggers>
        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Converter={StaticResource treeLevelConverter}}" Value="0" >
              <Setter TargetName="MyControl" Property="Background" Value="Red"/>
        </DataTrigger>
    </HierarchicalDataTemplate.Triggers>
  </HierarchicalDataTemplate>
</Window.Resources>

Then use the following Converter

  public class TreeLevelConverter : IValueConverter
  {
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
      var level = -1;
      if (value is DependencyObject )
      {
        var parent = VisualTreeHelper.GetParent(value as DependencyObject );
        while (!(parent is TreeView) && (parent != null))
        {
          if (parent is TreeViewItem) 
            level++;
          parent = VisualTreeHelper.GetParent(parent);
        }
      }
      return level;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
      throw new System.NotImplementedException();
    }
  }