Code Listing for 2005_10_20.aspx (VB)

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<%@ Page Language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

    ' Recursively searches the tree for all nodes at a given depth
    ' and adds them to a list of TreeNodes
    Private Sub FindNodesAtDepth(ByVal collection As TreeNodeCollection, _
                                 ByVal targetDepth As Integer, _
                                 ByVal targetNodes As Generic.List(Of TreeNode))

        For Each node As TreeNode In collection
            If node.Depth = targetDepth Then
                targetNodes.Add(node)
            ElseIf node.Depth < targetDepth Then
                FindNodesAtDepth(node.ChildNodes, targetDepth, targetNodes)
            End If
        Next
    End Sub

    ' Recursively creates a clone of a given TreeNode Hierarchy
    Private Sub CloneTreeNodeHierarchyRecursive(ByVal inCollection As TreeNodeCollection, _
                                                ByVal outCollection As TreeNodeCollection)

        For Each node As TreeNode In inCollection
            Dim clonedNode As TreeNode = CType(node, ICloneable).Clone()
            outCollection.Add(clonedNode)

            If node.ChildNodes.Count > 0 Then
                CloneTreeNodeHierarchyRecursive(node.ChildNodes, clonedNode.ChildNodes)
            End If
        Next
    End Sub

    ' Databound event handler for a TreeView
    Protected Sub TreeView_DataBound(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim Tree As TreeView = sender

        ' Only prune the tree if a node is selected
        If Tree.SelectedNode IsNot Nothing Then

            Dim childNodes As New Generic.List(Of TreeNode)()
            Dim childNodeCollection As New TreeNodeCollection()

            FindNodesAtDepth(Tree.Nodes, Tree.SelectedNode.Depth, childNodes)

            ' Copy from List(of TreeNode) to TreeNodeCollection
            For Each node As TreeNode In childNodes
                childNodeCollection.Add(node)
            Next

            ' Clear the TreeView nodes and add the nodes we found
            Tree.Nodes.Clear()
            CloneTreeNodeHierarchyRecursive(childNodeCollection, Tree.Nodes)

        End If


    End Sub

</script>