TreeView Control

TreeView Control Drill Down interface Displays information in a hierarchical manner. Nodes collection: Root: No parent Other nodes have a single parent. Siblings: Children have the same parent. First Sibling, Last Sibling TreeNode Editor

TreeView Properties TopNode Nodes GetNodeCount(False) SelectedNode Nodes(Index) GetNodeCount(False) SelectedNode FullPath

Display Root Node’s Children Dim TrNode As TreeNode For Each TrNode In TreeView1.TopNode.Nodes MessageBox.Show(TrNode.Text) MessageBox.Show(TrNode.FullPath) Nextree Note: Nodes is a collection of children nodes directly belong to a parent node.

Displaying Selected Node’s Information Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect MessageBox.Show(TreeView1.SelectedNode.Text) MessageBox.Show(TreeView1.SelectedNode.FullPath()) End Sub

Adding a TreeNode Programmatically Nodes collection’s Add method: Add(string) TreeView1.Nodes.Add("Root") Add(a tree node) Define a tree node object Dim myNode As New TreeNode() myNode.Text = "Root" TreeView1.Nodes.Add(myNode)

TreeView1.Nodes.Add("Root") TreeView1.Nodes(0).Nodes.Add("Child1") TreeView1.Nodes(0).Nodes.Add("Child2") TreeView1.Nodes(0).Nodes.Add("child3") TreeView1.Nodes(0).Nodes(0).Nodes.Add("GrandC11") TreeView1.Nodes(0).Nodes(0).Nodes.Add("GrandC12") TreeView1.Nodes(0).Nodes(1).Nodes.Add("GrandC21") TreeView1.Nodes(0).Nodes(2).Nodes.Add("GrandC31") TreeView1.Nodes(0).Nodes(2).Nodes.Add("GrandC32") TreeView1.Nodes(0).Nodes(2).Nodes(0).Nodes.Add("GGrandC311")

Recursive Procedure A procedure that calls itself.

Creating a TreeView of Directories Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim DiskDrive As String = "C:\" TreeView1.Nodes.Add(DiskDrive) Call GetFolders(TreeView1.Nodes(0)) End Sub Private Sub GetFolders(ByVal CurrentFolder As TreeNode) Dim FolderPath As String FolderPath = CurrentFolder.Text Dim folder As String If Directory.GetDirectories(FolderPath).Length <> 0 Then For Each folder In Directory.GetDirectories(FolderPath) Dim newNode As New TreeNode(folder) CurrentFolder.Nodes.Add(newNode) Call GetFolders(newNode) Next End If

Displaying Files in Selected Folder Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect Dim currDir As String currDir = TreeView1.SelectedNode.Text Dim fName As String ListBox1.Items.Clear() For Each fName In Directory.GetFiles(currDir) ListBox1.Items.Add(fName) Next End Sub