Option Explicit On
Option Strict On
 
Public Class Form1
    '// DesignerRegion
 
    Dim imgList As ImageList
    Dim idx As Integer
    Dim imgRoot As String = "D:\images"
 
    Private Sub Button1_Click(ByVal sender As System.Object, _
                              ByVal e As System.EventArgs) Handles Button1.Click
 
        Dim root As New MyTreeNode("My Images", MyTreeNode.NodeType.IsRootNode, _
          0)
        Me.imgList.Images.Clear()
        idx = 0
        imgList.Images.Add(New Bitmap(4, 4))
        Me.TreeView1.ImageList = imgList
        Me.TreeView1.BeginUpdate()
        Me.TreeView1.Nodes.Add(root)
        Me.SearchImages(imgRoot, root.Nodes)
        Me.TreeView1.EndUpdate()
    End Sub
 
    Private Sub FillImageListAndNode(ByVal fileName As String, _
                                     ByRef NodeColl As TreeNodeCollection)
 
        Dim img As Image = Image.FromFile(fileName)
        imgList.Images.Add(img)
        idx += 1
        NodeColl.Add(New MyTreeNode(fileName, MyTreeNode.NodeType.IsImage, idx))
    End Sub
 
    Private Sub GetImages(ByVal Dir As String, _
                          ByRef NodeColl As TreeNodeCollection)
 
        For Each f As String In IO.Directory.GetFiles(Dir)
            FillImageListAndNode(f, NodeColl)
        Next
    End Sub
 
    Private Sub SearchImages(ByVal Dir As String, _
                             ByRef NodeColl As TreeNodeCollection)
 
        Dim tn As New MyTreeNode(Dir, MyTreeNode.NodeType.IsFolder, 0)
        GetImages(Dir, tn.Nodes)
        NodeColl.Add(tn)
        For Each d As String In IO.Directory.GetDirectories(Dir)
            SearchImages(d, tn.Nodes)
        Next
    End Sub
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        imgList = New ImageList
    End Sub
 
    Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As _
      System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
        Dim tn As MyTreeNode = CType(Me.TreeView1.SelectedNode, MyTreeNode)
        Me.Label1.Text = "INFO: " + tn.ToString()
    End Sub
End Class
 
Public Class MyTreeNode
    Inherits TreeNode
    Public TreeNodeType As NodeType
 
    Public Sub New(ByVal Text As String, _
                   ByVal NodeType As NodeType, _
                   ByVal ImageIndex As Integer)
 
        Me.Text = Text
        Me.TreeNodeType = NodeType
        Me.ImageIndex = ImageIndex
        Me.SelectedImageIndex = Me.ImageIndex
    End Sub
 
    Public Enum NodeType
        IsFolder
        IsImage
        IsRootNode
    End Enum
 
    Public Overrides Function ToString() As String
        Return String.Format( _
                              "Text: {0} " + _
                              "ImageIndex: {1} " + _
                              "NodeType: {2} ", _
                              Me.Text, _
                              Me.ImageIndex, _
                              Me.TreeNodeType.ToString() _
                            )
    End Function
 
End Class

D:\IMAGES
+---img1
|   +---img1
|   \---img2
+---img2
|   +---img1
|   \---img2
\---img3
    +---img1
    \---img2