Add Connecting Lines to WPF TreeView Programmatically (with no XAML)

Question

How might I do THIS: How to make WPF TreeView style as WinForms TreeView? in code, with no XAML? The reason I need to do this is the TreeView I have been given is defined in code, so there is no XAML at all. While I can start with XAML, I do not know how to 'add XAML' to something that doesn't have it to begin with. I am very new to WPF, but have been doing Winforms for years. The TreeView is comprised only of a large hierarchy of TreeViewItem objects with Header and Tag values.

Answer 1

If you look at the answer to the article you linked to, it details a TreeViewItem style defined like this:-

<Style x:Key="{x:Type TreeViewItem}" TargetType="{x:Type TreeViewItem}">

When the x:Key is set to the target type (or omitted entirely), the style should become the application default for that control type.

If you add the styles detailed in that article's answer to your App.xaml file, all TreeViewItems throughout your application should take on this default style.

If this doesn't work, you can try one more thing. Change the style's key to a string, e.g.:-

<Style x:Key="WindowsTreeViewItemStyle" TargetType="{x:Type TreeViewItem}">

Then in your code, iterate through the TreeViewItems in the TreeView, and assign the style to each one programmatically:-

var style = (Style)Application.Current.FindResource("WindowsTreeViewItemStyle");

foreach (var treeViewItem in ...)
{
   treeviewitem.Style = style;
}

(Use that article's XAML at your own risk - the link to the complete source zip is dead, and what's detailed in his SO answer may be incomplete!)