Option Strict On
Option Explicit On
 
Imports System.Runtime.InteropServices
 
Partial Public Class MainForm
 
    Public Const TV_FIRST As Integer = 4352
    Public Const TVSIL_NORMAL As Integer = 0
    Public Const TVSIL_STATE As Integer = 2
    Public Const TVM_SETIMAGELIST As Integer = TV_FIRST + 9
    Public Const TVM_GETNEXTITEM As Integer = TV_FIRST + 10
    Public Const TVIF_HANDLE As Integer = 16
    Public Const TVIF_STATE As Integer = 8
    Public Const TVIF_IMAGE As Integer = 2
    Public Const TVIS_STATEIMAGEMASK As Integer = 61440
    Public Const TVM_SETITEM As Integer = TV_FIRST + 13
    Public Const TVGN_ROOT As Integer = 0
    '// Public Const TVM_GETITEM As Integer = TV_FIRST + 62
    '// TVM_GETITEMA (TV_FIRST + 12)
    Public Const TVM_GETITEM As Integer = TV_FIRST + 12
    Public Const MY_MAXLVITEMTEXT As Integer = 127
    Private Const TVIF_TEXT As Int32 = &H1
 
    <StructLayout(LayoutKind.Sequential, Pack:=8, CharSet:=CharSet.Auto)> _
    Public Structure TVITEM
        Dim mask As Integer
        Dim hItem As IntPtr
        Dim state As Integer
        Dim stateMask As Integer
        Dim pszText As IntPtr
        Dim cchTextMax As Integer
        Dim iImage As Integer
        Dim iSelectedImage As Integer
        Dim cChildren As Integer
        Dim lParam As IntPtr
    End Structure
 
    <DllImport("user32.dll")> _
    Public Overloads Shared Function SendMessage _
        (ByVal hWnd As IntPtr, ByVal Msg As Integer, _
        ByVal wParam As Integer, ByVal lParam As Integer) As Integer
    End Function
 
    <DllImport("User32.dll", CharSet:=CharSet.Auto)> _
    Public Overloads Shared Function SendMessage _
        (ByVal hWnd As IntPtr, ByVal msg As Integer, _
        ByVal wParam As Integer, ByRef lParam As TVITEM) As Integer
    End Function
 
    Private Declare Function LocalAlloc _
    Lib "kernel32.dll" (ByVal wFlags As Int32, ByVal wBytes As Int32) As Int32
 
    Public Sub New()
        ' The Me.InitializeComponent call is required for Windows Forms 
        ' designer support.
        Me.InitializeComponent()
        '
        ' TODO : Add constructor code after InitializeComponents
        '
    End Sub
 
    Sub FillTreeView()
        With Me.AxTreeView1
            .Nodes.Add(, "root", "root", "node0")
            .Nodes.Add(, "root", , "node1")
        End With
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim tvi As New TVITEM
        Dim hWnd As IntPtr = New IntPtr(Me.AxTreeView1.hWnd) _
          'Me.TreeView1.Handle
        Dim pszText As IntPtr = IntPtr.Zero
        Dim buffer As String = Nothing
        Dim hRoot As IntPtr = IntPtr.op_Explicit(SendMessage(hWnd, _
          TVM_GETNEXTITEM, TVGN_ROOT, 0))
        tvi.hItem = hRoot
        tvi.state = 0
        SendMessage(hWnd, TVM_GETITEM, 0, tvi)
        pszText = New IntPtr(LocalAlloc(&H40, MY_MAXLVITEMTEXT))
        tvi.mask = TVIF_TEXT
        tvi.hItem = hRoot
        tvi.cchTextMax = MY_MAXLVITEMTEXT
        tvi.pszText = pszText
        SendMessage(hWnd, TVM_GETITEM, 0, tvi)
        '// buffer = Marshal.PtrToStringUni(tvi.pszText, MY_MAXLVITEMTEXT)
        buffer = Marshal.PtrToStringAnsi(tvi.pszText, MY_MAXLVITEMTEXT)
        Debug.WriteLine(buffer)
        MessageBox.Show(buffer)
    End Sub
 
    Private Sub MainForm_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        FillTreeView()
    End Sub
 
End Class