How to get the TreeView from inside the ItemTemplate class? - wpf

Question

I have a TreeView class like so, which has my own class "EntryPanel" as an ItemTemplate:
<TreeView x:Class="PowerNote.MyEntriesView"
xmlns:local="clr-namespace:PowerNote"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
ItemsSource = "{Binding viewStudents}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Children}">
<local:EntryPanel/>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
In my EntryPanel.xaml.cs code, I would like to access the TreeView. I tried Parent, and TemplateParent, but neither would work. How can I achieve this?

Answer 1

Try Doing in this way to Find the Parent.
public static T TryFindParent<T>(this DependencyObject child)
where T : DependencyObject
{
//get parent item
DependencyObject parentObject = GetParentObject(child);
//we've reached the end of the tree
if (parentObject == null) return null;
//check if the parent matches the type we're looking for
T parent = parentObject as T;
if (parent != null)
{
return parent;
}
else
{
//use recursion to proceed with next level
return TryFindParent<T>(parentObject);
}
}
This one will find the parent object.
public static DependencyObject GetParentObject(this DependencyObject child)
{
if (child == null) return null;
//handle content elements separately
ContentElement contentElement = child as ContentElement;
if (contentElement != null)
{
DependencyObject parent = ContentOperations.GetParent(contentElement);
if (parent != null) return parent;
FrameworkContentElement fce = contentElement as FrameworkContentElement;
return fce != null ? fce.Parent : null;
}
//also try searching for parent in framework elements (such as DockPanel, etc)
FrameworkElement frameworkElement = child as FrameworkElement;
if (frameworkElement != null)
{
DependencyObject parent = frameworkElement.Parent;
if (parent != null) return parent;
}
//if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper
return VisualTreeHelper.GetParent(child);
}
This snippet works with arbitrary dependency objects that are of Type Visual or Visual3D. So let’s say you need a reference to the Window that hosts a given Button control somewhere, all you need is this:
Button myButton = ...
Window parentWindow = UIHelper.TryFindParent<Window>(myButton);
The above TryFindParent method also makes it easy to get an item at a given position. The method below performs a hit test based on a given position. If hit testing does not return the requested item (e.g. a clicked CheckBox on a tree, while you are keen on the TreeViewItem that hosts the CheckBox), the procedure delegates the lookup to TryFindParent.
This comes in very handy for mouse-related events if you just need to now what’s under your mouse pointer:
public static T TryFindFromPoint<T>(UIElement reference, Point point)
where T:DependencyObject
{
DependencyObject element = reference.InputHitTest(point)
as DependencyObject;
if (element == null) return null;
else if (element is T) return (T)element;
else return TryFindParent<T>(element);
}
Reference