Csharp/CSharp Tutorial/GUI Windows Forms/TreeView

Directory TreeView

<source lang="csharp">using System; using System.Drawing; using System.IO; using System.Windows.Forms; class MyClass : Form {

   public static void Main()
   {
       Application.Run(new MyClass());
   }
   public MyClass()
   {
       TreeView tree = new TreeView();
       tree.Parent = this;
       tree.Dock = DockStyle.Fill;
       TreeNode nodeDriveC = new TreeNode("C:\\");
       tree.Nodes.Add(nodeDriveC);
       AddDirectories(nodeDriveC);
   }
   void AddDirectories(TreeNode node)
   {
       string strPath = node.FullPath;
       DirectoryInfo dirinfo = new DirectoryInfo(strPath);
       DirectoryInfo[] adirinfo;
       adirinfo = dirinfo.GetDirectories();
       foreach (DirectoryInfo di in adirinfo)
       {
           TreeNode nodeDir = new TreeNode(di.Name);
           node.Nodes.Add(nodeDir);
           AddDirectories(nodeDir);
       }
   }

}</source>

Hierarchical Tree View for displaying database table

<source lang="csharp">using System.Data; using System.Data.SqlClient; using System; using System.Drawing; using System.Collections; using System.ruponentModel; using System.Windows.Forms;

 public class HierarchicalTreeView : System.Windows.Forms.Form
 {
   private System.Windows.Forms.TreeView tree;
   public HierarchicalTreeView()
   {
     this.tree = new System.Windows.Forms.TreeView();
     this.SuspendLayout();
     // 
     this.tree.ImageIndex = -1;
     this.tree.Location = new System.Drawing.Point(8, 8);
     this.tree.Name = "tree";
     this.tree.SelectedImageIndex = -1;
     this.tree.Size = new System.Drawing.Size(276, 248);
     this.tree.TabIndex = 0;
     this.AutoScaleBaseSize = new System.Drawing.Size(5, 14);
     this.ClientSize = new System.Drawing.Size(292, 266);
     this.Controls.AddRange(new System.Windows.Forms.Control[] {this.tree});
     this.Text = "Hierarchical TreeView";
     this.Load += new System.EventHandler(this.HierarchicalTreeView_Load);
     this.ResumeLayout(false);
   }
   string connectionString = "Data Source=localhost;Initial Catalog=Northwind;Integrated Security=SSPI";
   string categorySQL = "SELECT * FROM Categories";
   string productSQL = "SELECT * FROM Products";
   private void HierarchicalTreeView_Load(object sender, System.EventArgs e)
   {
     SqlConnection con = new SqlConnection(connectionString);
     SqlCommand com = new SqlCommand(categorySQL, con);
     SqlDataAdapter adapter = new SqlDataAdapter(com);
     DataSet ds = new DataSet();
   
     con.Open();
     adapter.Fill(ds, "Categories");
     adapter.SelectCommand.rumandText = productSQL;
     adapter.Fill(ds, "Products");
     con.Close();
     DataColumn parentCol = ds.Tables["Categories"].Columns["CategoryID"];
     DataColumn childCol = ds.Tables["Products"].Columns["CategoryID"];
     DataRelation relation = new DataRelation("Cat_Prod", parentCol, childCol);
     ds.Relations.Add(relation);
     foreach (DataRow parent in ds.Tables["Categories"].Rows)
     {
       TreeNode nodeParent = tree.Nodes.Add(parent["CategoryName"].ToString());
       foreach (DataRow child in parent.GetChildRows(relation))
       {
         nodeParent.Nodes.Add(child["ProductName"].ToString());
       }    
     }
   }
   public static void Main()
   {
     Application.Run(new HierarchicalTreeView());
   }
 }</source>

Simple Treeview

<source lang="csharp">using System; using System.Drawing; using System.Collections; using System.ruponentModel; using System.Windows.Forms; using System.Data;

 public class SimpleTvForm : System.Windows.Forms.Form
 {
   private System.Windows.Forms.TreeView tvSimple;
   private System.Windows.Forms.Button cmdExpandAll;
   private System.Windows.Forms.Button cmdCollapseAll;
   private System.Windows.Forms.ContextMenu ctxmTvNodes;
   private System.Windows.Forms.MenuItem mnuExpandNode;
   private System.Windows.Forms.MenuItem mnuCollapseNode;
   public SimpleTvForm()
   {
     this.tvSimple = new System.Windows.Forms.TreeView();
     this.ctxmTvNodes = new System.Windows.Forms.ContextMenu();
     this.mnuExpandNode = new System.Windows.Forms.MenuItem();
     this.mnuCollapseNode = new System.Windows.Forms.MenuItem();
     this.cmdExpandAll = new System.Windows.Forms.Button();
     this.cmdCollapseAll = new System.Windows.Forms.Button();
     this.SuspendLayout();
     // 
     // tvSimple
     // 
     this.tvSimple.ContextMenu = this.ctxmTvNodes;
     this.tvSimple.ImageIndex = -1;
     this.tvSimple.Location = new System.Drawing.Point(8, 8);
     this.tvSimple.Name = "tvSimple";
     this.tvSimple.Nodes.AddRange(new System.Windows.Forms.TreeNode[] {
                                        new System.Windows.Forms.TreeNode("Continents", new System.Windows.Forms.TreeNode[] {
                                                                                    new System.Windows.Forms.TreeNode("Africa"),
                                                                                    new System.Windows.Forms.TreeNode("America"),
                                                                                    new System.Windows.Forms.TreeNode("Europe"),
                                                                                    new System.Windows.Forms.TreeNode("Asia"),
                                                                                    new System.Windows.Forms.TreeNode("Australia")}),
                                        new System.Windows.Forms.TreeNode("SUV\"s", new System.Windows.Forms.TreeNode[] {
                                                                                  new System.Windows.Forms.TreeNode("Hummer"),
                                                                                  new System.Windows.Forms.TreeNode("Pinzgauer")})});
     this.tvSimple.SelectedImageIndex = -1;
     this.tvSimple.Size = new System.Drawing.Size(272, 232);
     this.tvSimple.TabIndex = 0;
     this.tvSimple.AfterSelect += new System.Windows.Forms.TreeViewEventHandler(this.AfterSelect);
     // 
     // ctxmTvNodes
     // 
     this.ctxmTvNodes.MenuItems.AddRange(new System.Windows.Forms.MenuItem[] {
                                           this.mnuExpandNode,
                                           this.mnuCollapseNode});
     // 
     // mnuExpandNode
     // 
     this.mnuExpandNode.Index = 0;
     this.mnuExpandNode.Text = "Expand node";
     this.mnuExpandNode.Click += new System.EventHandler(this.OnExpandNode);
     // 
     // mnuCollapseNode
     // 
     this.mnuCollapseNode.Index = 1;
     this.mnuCollapseNode.Text = "Collapse node";
     this.mnuCollapseNode.Click += new System.EventHandler(this.OnCollapseNode);
     // 
     // cmdExpandAll
     // 
     this.cmdExpandAll.Location = new System.Drawing.Point(8, 256);
     this.cmdExpandAll.Name = "cmdExpandAll";
     this.cmdExpandAll.TabIndex = 1;
     this.cmdExpandAll.Text = "expand all";
     this.cmdExpandAll.Click += new System.EventHandler(this.cmdExpandAll_Click);
     // 
     // cmdCollapseAll
     // 
     this.cmdCollapseAll.Location = new System.Drawing.Point(96, 256);
     this.cmdCollapseAll.Name = "cmdCollapseAll";
     this.cmdCollapseAll.TabIndex = 2;
     this.cmdCollapseAll.Text = "collapse all";
     this.cmdCollapseAll.Click += new System.EventHandler(this.cmdCollapseAll_Click);
     // 
     // SimpleTvForm
     // 
     this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
     this.ClientSize = new System.Drawing.Size(292, 301);
     this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                     this.cmdCollapseAll,
                                     this.cmdExpandAll,
                                     this.tvSimple});
     this.Name = "SimpleTvForm";
     this.Text = "Simple";
     this.ResumeLayout(false);
   }
   static void Main() 
   {
     Application.Run(new SimpleTvForm());
   }
   private void AfterSelect(object sender, System.Windows.Forms.TreeViewEventArgs e)
   {
     // MessageBox.Show("Node " +  e.Node.FullPath + " was selected");
   }
   private void cmdExpandAll_Click(object sender, System.EventArgs e)
   {
     tvSimple.ExpandAll();
   }
   private void cmdCollapseAll_Click(object sender, System.EventArgs e)
   {
     tvSimple.CollapseAll();
   }
   private void OnExpandNode(object sender, System.EventArgs e)
   {
     TreeNode tn = tvSimple.SelectedNode;
     if (null == tn) return;
     tn.ExpandAll();
   }
   private void OnCollapseNode(object sender, System.EventArgs e)
   {
     TreeNode tn = tvSimple.SelectedNode;
     if (null == tn) return;
     tn.Collapse();
   }
 }</source>

Tree node foreground and background color, tooltips

<source lang="csharp">using System; using System.Collections.Generic; using System.ruponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; public partial class Form1 : Form {

   public Form1()
   {
       InitializeComponent();
   }
   private void button1_Click(object sender, EventArgs e)
   {
       treeView1.Nodes.Clear();
       treeView1.ShowNodeToolTips = true;
       TreeNode evenNumbers = treeView1.Nodes.Add("Even", "Even Numbers", 0,1);
       evenNumbers.BackColor = Color.Blue;
       evenNumbers.ForeColor = Color.Yellow;
       evenNumbers.ToolTipText = "The even numbers";
       TreeNode oddNumbers =  treeView1.Nodes.Add("Odd", "Odd Numbers", 0,1);
       oddNumbers.BackColor = Color.Yellow;
       oddNumbers.ForeColor = Color.Blue;
       oddNumbers.ToolTipText = "The odd numbers";
       for (int i = 1; i < 50; i++)
       {
           if (i % 2 == 0)
           {
               evenNumbers.Nodes.Add(i.ToString());
           } else {
               oddNumbers.Nodes.Add(i.ToString() );
           }
       }
   }
   private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
   {
       TreeNode selectedNode = e.Node;
       if (selectedNode.Nodes.ContainsKey("1"))
       {
           Console.WriteLine("This node contains "1"");
       }
   }

} partial class Form1 {

   private void InitializeComponent()
   {
       this.treeView1 = new System.Windows.Forms.TreeView();
       this.button1 = new System.Windows.Forms.Button();
       this.SuspendLayout();
       // 
       // treeView1
       // 
       this.treeView1.Location = new System.Drawing.Point(16, 50);
       this.treeView1.Margin = new System.Windows.Forms.Padding(4, 4, 4, 4);
       this.treeView1.Name = "treeView1";
       this.treeView1.Size = new System.Drawing.Size(194, 149);
       this.treeView1.TabIndex = 0;
       this.treeView1.NodeMouseClick += new System.Windows.Forms.TreeNodeMouseClickEventHandler(this.treeView1_NodeMouseClick);
       // 
       // button1
       // 
       this.button1.Location = new System.Drawing.Point(16, 15);
       this.button1.Margin = new System.Windows.Forms.Padding(4, 4, 4, 4);
       this.button1.Name = "button1";
       this.button1.Size = new System.Drawing.Size(100, 28);
       this.button1.TabIndex = 1;
       this.button1.Text = "Load";
       this.button1.Click += new System.EventHandler(this.button1_Click);
       // 
       // Form1
       // 
       this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 16F);
       this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
       this.ClientSize = new System.Drawing.Size(229, 213);
       this.Controls.Add(this.button1);
       this.Controls.Add(this.treeView1);
       this.Margin = new System.Windows.Forms.Padding(4, 4, 4, 4);
       this.Name = "Form1";
       this.Text = "Form1";
       this.ResumeLayout(false);
   }
   private System.Windows.Forms.TreeView treeView1;
   private System.Windows.Forms.Button button1;
   private System.Windows.Forms.ImageList imageList1;

} public class TreeViewNodeBackgroundForegroundTooltip {

   [STAThread]
   static void Main()
   {
       Application.EnableVisualStyles();
       Application.Run(new Form1());
   }

}</source>

TreeView: Add Nodes

<source lang="csharp">using System; using System.Collections.Generic; using System.ruponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; public partial class Form1 : Form {

   public Form1()
   {
       InitializeComponent();
   }
   private void button1_Click(object sender, EventArgs e)
   {
       treeView1.Nodes.Clear();
       TreeNode evenNumbers = treeView1.Nodes.Add("Even Numbers");
       TreeNode oddNumbers =  treeView1.Nodes.Add("Odd Numbers");
       for (int i = 1; i < 500; i++)
       {
           if (i % 2 == 0)
           {
               evenNumbers.Nodes.Add(i.ToString());
           } else {
               oddNumbers.Nodes.Add(i.ToString() );
           }
       }
   }

} partial class Form1 {

   private void InitializeComponent()
   {
       this.treeView1 = new System.Windows.Forms.TreeView();
       this.button1 = new System.Windows.Forms.Button();
       this.SuspendLayout();
       // 
       // treeView1
       // 
       this.treeView1.Location = new System.Drawing.Point(16, 50);
       this.treeView1.Margin = new System.Windows.Forms.Padding(4);
       this.treeView1.Name = "treeView1";
       this.treeView1.Size = new System.Drawing.Size(286, 313);
       this.treeView1.TabIndex = 0;
       // 
       // button1
       // 
       this.button1.Location = new System.Drawing.Point(16, 15);
       this.button1.Margin = new System.Windows.Forms.Padding(4);
       this.button1.Name = "button1";
       this.button1.Size = new System.Drawing.Size(100, 28);
       this.button1.TabIndex = 1;
       this.button1.Text = "Load";
       this.button1.Click += new System.EventHandler(this.button1_Click);
       // 
       // Form1
       // 
       this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 16F);
       this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
       this.ClientSize = new System.Drawing.Size(316, 390);
       this.Controls.Add(this.button1);
       this.Controls.Add(this.treeView1);
       this.Margin = new System.Windows.Forms.Padding(4);
       this.Name = "Form1";
       this.Text = "Form1";
       this.ResumeLayout(false);
   }
   private System.Windows.Forms.TreeView treeView1;
   private System.Windows.Forms.Button button1;

} public class TreeViewAddItems {

   [STAThread]
   static void Main()
   {
       Application.EnableVisualStyles();
       Application.Run(new Form1());
   }

}</source>

TreeView selection event

<source lang="csharp">using System; using System.Drawing; using System.Collections; using System.ruponentModel; using System.Windows.Forms; using System.Data; public class Form1 : Form {

 private TreeView treeView1;
 private Splitter splitter1;
 private ListView listView1;
 public Form1()
 {
   InitializeComponent();
 }
 private void InitializeComponent()
 {
   this.treeView1 = new TreeView();
   this.splitter1 = new Splitter();
   this.listView1 = new ListView();
   this.SuspendLayout();
   this.treeView1.Dock = DockStyle.Left;
   this.treeView1.Name = "treeView1";
   this.treeView1.Nodes.AddRange(new TreeNode[] {new TreeNode("Vehicles", 0, 0, new TreeNode[] {new TreeNode("Cars", 0, 0, new TreeNode[] {new TreeNode("Item1", 0, 0),new TreeNode("Item2", 0, 0)}),new TreeNode("Trucks", 0, 0, new TreeNode[] {
       new TreeNode("Pickups"),new TreeNode("Utility vans")})})});
   this.treeView1.Size = new System.Drawing.Size(192, 293);
   this.treeView1.TabIndex = 0;
   this.treeView1.AfterSelect += new TreeViewEventHandler(this.treeView1_AfterSelect);
   // 
   // splitter1
   // 
   this.splitter1.Location = new System.Drawing.Point(192, 0);
   this.splitter1.Name = "splitter1";
   this.splitter1.Size = new System.Drawing.Size(3, 293);
   this.splitter1.TabIndex = 1;
   this.splitter1.TabStop = false;
   // 
   // listView1
   // 
   this.listView1.Dock = DockStyle.Fill;
   this.listView1.Location = new System.Drawing.Point(195, 0);
   this.listView1.Name = "listView1";
   this.listView1.Size = new System.Drawing.Size(141, 293);
   this.listView1.TabIndex = 2;
   this.listView1.View = View.List;
   this.listView1.ItemActivate += new System.EventHandler(this.listView1_ItemActivate);
   // 
   // Form1
   // 
   this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
   this.ClientSize = new System.Drawing.Size(336, 293);
   this.Controls.AddRange(new Control[] {
                                            this.listView1,
                                            this.splitter1,
                                            this.treeView1});
   this.Name = "Form1";
   this.Text = "Vehicle Hierarchy";
   this.ResumeLayout(false);
 }
 [STAThread]
 static void Main() 
 {
   Application.Run(new Form1());
 }
 private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
 {
    switch (e.Node.Text)
    {
       case "Item1":
          listView1.Clear();
          listView1.Items.Add("A",3);
          listView1.Items.Add("B", 4);
          listView1.Items.Add("C", 6);
          break;
          
       case "Item2":
          listView1.Clear();
          listView1.Items.Add("D", 1);
          listView1.Items.Add("E", 2);
          listView1.Items.Add("F", 5);
          break;
    }
 }
 
 private void listView1_ItemActivate(object sender, System.EventArgs e) {
  String strItem = listView1.FocusedItem.Text;
  MessageBox.Show(strItem);
 }

}</source>

Use TreeView to display Directories

<source lang="csharp">/* Quote from Programming .NET Windows Applications By Jesse Liberty, Dan Hurwitz First Edition October 2003 Pages: 1246 (More details)

• /

using System; using System.Drawing; using System.Windows.Forms; using System.IO; // necessary for Directory info public class TreeViewDirectories : Form {

 TreeView tvw;
 CheckBox cb;
 Button btnSelected;
 Button btnExpand;
 Button btnExpandAll;
 Button btnCollapse;
 Button btnCollapseAll;
 Button btnToggle;
 public TreeViewDirectories()
 {
   Size = new Size(400,600);
   ImageList imgList = new ImageList();
   Image img;
   String[] arFiles = {"1.ico","2.ico","3.ico",".ico"};

   for (int i = 0; i < arFiles.Length; i++)
   {
     img = Image.FromFile(arFiles[i]);
     imgList.Images.Add(img);
   }
   tvw = new TreeView();
   tvw.Parent = this;
   tvw.Location = new Point(10,10);
   tvw.Size = new Size(ClientSize.Width - 20, Height - 200);
   tvw.Anchor = AnchorStyles.Top | AnchorStyles.Left | 
         AnchorStyles.Right | AnchorStyles.Bottom;
   tvw.BackColor = Color.Moccasin;
   tvw.ForeColor = Color.DarkRed;
   tvw.BorderStyle = BorderStyle.Fixed3D;
   tvw.FullRowSelect = false;    
   tvw.ShowLines = true;      
   tvw.ShowPlusMinus = true;    
   tvw.Scrollable = true;      
   tvw.HideSelection = false;  
   tvw.HotTracking = true;  
   tvw.ImageList = imgList;
   tvw.ImageIndex = 1;
   tvw.SelectedImageIndex = 2;
   tvw.Indent = 35;
   tvw.Font = new Font("Times New Roman", 20f);
   tvw.ItemHeight = tvw.Font.Height * 2;
   tvw.BeforeExpand += new TreeViewCancelEventHandler(tvw_BeforeExpand);
   cb = new CheckBox();
   cb.Parent = this;
   cb.Location = new Point((Width - cb.Width) * 2 / 10, tvw.Bottom + 25);
   cb.Text = "Show Files";
   cb.Anchor = AnchorStyles.Bottom;
   cb.CheckedChanged += new EventHandler(cb_CheckedChanged);
   btnSelected = new Button();
   btnSelected.Parent = this;
   btnSelected.Text = "&SelectedNode";
   int xSize = ((int)(Font.Height * .75) * btnSelected.Text.Length);
   int ySize = Font.Height + 10;
   btnSelected.Size = new Size(xSize, ySize);
   btnSelected.Location = new Point(cb.Left, cb.Bottom + ySize);
   btnSelected.Anchor = AnchorStyles.Bottom;
   btnSelected.Click += new EventHandler(btnSelected_Click);
   btnToggle = new Button();
   btnToggle.Parent = this;
   btnToggle.Location = new Point((Width - cb.Width) * 7 / 10,
                                     cb.Top);
   btnToggle.Text = "&Toggle";
   btnToggle.Size = new Size(btnSelected.Width, btnSelected.Height);
   btnToggle.Anchor = AnchorStyles.Bottom;
   btnToggle.Click += new EventHandler(btnToggle_Click);
   btnExpand = new Button();
   btnExpand.Parent = this;
   btnExpand.Location = new Point(btnToggle.Left, btnToggle.Bottom);
   btnExpand.Text = "&Expand";
   btnExpand.Size = new Size(btnSelected.Width, btnSelected.Height);
   btnExpand.Anchor = AnchorStyles.Bottom;
   btnExpand.Click += new EventHandler(btnExpand_Click);
   btnExpandAll = new Button();
   btnExpandAll.Parent = this;
   btnExpandAll.Location = new Point(btnExpand.Left, btnExpand.Bottom);
   btnExpandAll.Text = "Expand &All";
   btnExpandAll.Size = new Size(btnSelected.Width, btnSelected.Height);
   btnExpandAll.Anchor = AnchorStyles.Bottom;
   btnExpandAll.Click += new EventHandler(btnExpandAll_Click);
   btnCollapse = new Button();
   btnCollapse.Parent = this;
   btnCollapse.Location = new Point(btnExpandAll.Left, btnExpandAll.Bottom);
   btnCollapse.Text = "&Collapse";
   btnCollapse.Size = new Size(btnSelected.Width, btnSelected.Height);
   btnCollapse.Anchor = AnchorStyles.Bottom;
   btnCollapse.Click += new EventHandler(btnCollapse_Click);
   btnCollapseAll = new Button();
   btnCollapseAll.Parent = this;
   btnCollapseAll.Location = new Point(btnCollapse.Left, btnCollapse.Bottom);
   btnCollapseAll.Text = "Colla&pse All";
   btnCollapseAll.Size = new Size(btnSelected.Width, btnSelected.Height);
   btnCollapseAll.Anchor = AnchorStyles.Bottom;
   btnCollapseAll.Click += new EventHandler(btnCollapseAll_Click);
   FillDirectoryTree();
 }
 static void Main() 
 {
   Application.Run(new TreeViewDirectories());
 }
 private void FillDirectoryTree()
 {
   tvw.BeginUpdate();
   tvw.Nodes.Clear();
   string[] strDrives = Environment.GetLogicalDrives();
       foreach (string rootDirectoryName in strDrives)
      {
     try 
     {
       Directory.GetDirectories(rootDirectoryName);
       TreeNode ndRoot = new TreeNode(rootDirectoryName);
       tvw.Nodes.Add(ndRoot);
       if (ndRoot.Index % 2 == 0)
       {
         ndRoot.BackColor = Color.LightYellow;
         ndRoot.ForeColor = Color.Green;
       }
       GetSubDirectoryNodes(ndRoot, cb.Checked);
     }
     catch  (System.IO.IOException)
     {
           }
     catch  (Exception e)
     {
       MessageBox.Show(e.Message);
           }
   }
    
     tvw.EndUpdate();
    
 }
 private void GetSubDirectoryNodes(TreeNode parentNode, bool getFileNames)
 {
   DirectoryInfo di = new DirectoryInfo(parentNode.FullPath);
   if ((di.Attributes & FileAttributes.Directory) == 0)
   {
     return;
   }
   parentNode.Nodes.Clear();
   string[] arSubs = Directory.GetDirectories(parentNode.FullPath);
   foreach (string subDir in arSubs)
   {
         DirectoryInfo dirInfo = new DirectoryInfo(subDir);
           if ((dirInfo.Attributes & FileAttributes.Hidden)!= 0)
           {
              continue;
           }
     TreeNode subNode = new TreeNode(dirInfo.Name);
     parentNode.Nodes.Add(subNode);
       
     //  Set colors based on Index property.
     if (subNode.Index % 2 == 0)
       subNode.BackColor = Color.LightPink;
   }
   if (getFileNames)
   {
           //  Get any files for this node.
         string[] files = Directory.GetFiles(parentNode.FullPath);
           // After placing the nodes, 
           // now place the files in that subdirectory.
           foreach (string str in files)
           {
       FileInfo fi = new FileInfo(str);
       TreeNode fileNode = new TreeNode(fi.Name);
       parentNode.Nodes.Add(fileNode);
       //  Set the icon
       fileNode.ImageIndex = 0;
       fileNode.SelectedImageIndex = 3;
       //  Set colors based on Index property.
       if (fileNode.Index % 2 == 0)
         fileNode.BackColor = Color.LightGreen;
           }
   }
 }  // close GetSubDirectoryNodes

 private void cb_CheckedChanged(object sender, EventArgs e)
 {
   FillDirectoryTree();
 }
 private void tvw_BeforeExpand(object sender, 
               TreeViewCancelEventArgs e)
 {
   tvw.BeginUpdate();
   foreach (TreeNode tn in e.Node.Nodes)
   {
     GetSubDirectoryNodes(tn, cb.Checked);
   }
   tvw.EndUpdate();      
 }    
 private void btnSelected_Click(object sender, EventArgs e)
 {
   MessageBox.Show(tvw.SelectedNode.ToString() + "\n" +
       "FullPath:\t" + tvw.SelectedNode.FullPath.ToString() + "\n" +
          "Index:\t" + tvw.SelectedNode.Index.ToString());
 }
 private void btnExpand_Click(object sender, EventArgs e)
 {
   tvw.SelectedNode.Expand();
 }
 private void btnExpandAll_Click(object sender, EventArgs e)
 {
   tvw.SelectedNode.ExpandAll();
 }
 private void btnCollapse_Click(object sender, EventArgs e)
 {
   tvw.SelectedNode.Collapse();
 }
 private void btnCollapseAll_Click(object sender, EventArgs e)
 {
   tvw.CollapseAll();
 }
 private void btnToggle_Click(object sender, EventArgs e)
 {
   tvw.SelectedNode.Toggle();
 }

}</source>