Getting the SelectedIndex of a child node in a TreeView

Question

I am currently working on a wpf project in C#.

I have a treeview created that has parent nodes with childen nodes inside of it.

I was wondering if there was a way to get the index of the child node the user clicked on. (Simmilar to ".SelectedIndex" when using comboboxes)

I have tried Various ways such as:

int val =TreeView.SelectedItemProperty.GlobalIndex;

and

fileInput.IndexOf(treeView1.SelectedItem);

But they dont seem to work.

Any suggestions or comments are greatly appreciated.

Thanks