Get a list of all tree nodes (in all levels) in TreeView Controls

Question

How can I get a list of all tree nodes (in all levels) in a TreeView control?

Answer 1

I think my solution is more elegant, it uses generics (because TreeView can store each kind of objects derived from TreeNode) and has a single function recursively called. It should be straightforward also convert this as extension.

    List EnumerateAllTreeNodes(TreeView tree, T parentNode = null) where T : TreeNode
    {
        if (parentNode != null && parentNode.Nodes.Count == 0)
            return new List() { };

        TreeNodeCollection nodes = parentNode != null ? parentNode.Nodes : tree.Nodes;
        List childList = nodes.Cast().ToList();

        List result = new List(1024); //Preallocate space for children
        result.AddRange(childList); //Level first

        //Recursion on each child node
        childList.ForEach(n => result.AddRange(EnumerateAllTreeNodes(tree,n)));

        return result;
    }

The usage is straightforward, just call:

    List allnodes = EnumerateAllTreeNodes(tree);