'=====================================================================================
 ' Browse for a Folder using SHBrowseForFolder API function with a callback
 ' function BrowseCallbackProc.
 '
 ' This Extends the functionality that was given in the
 ' MSDN Knowledge Base article Q179497 "HOWTO: Select a Directory
 ' Without the Common Dialog Control".
 '
 ' After reading the MSDN knowledge base article Q179378 "HOWTO: Browse for
 ' Folders from the Current Directory", I was able to figure out how to add
 ' a callback function that sets the starting directory and displays the
 ' currently selected path in the "Browse For Folder" dialog.
 '
 ' I used VB 6.0 (SP3) to compile this code.  Should work in VB 5.0.
 ' However, because it uses the AddressOf operator this code will not
 ' work with versions below 5.0.
 '
 ' This code works in Window 95a so I assume it will work with later versions.
 '
 ' Stephen Fonnesbeck
 ' steev@xmission.com
 ' http://www.xmission.com/~steev
 ' Feb 20, 2000
 '
 '=====================================================================================
 ' Usage:
 '
 '    Dim folder As String
 '    folder = BrowseForFolder(Me, "Select A Directory", "C:\startdir\anywhere" )
 '    If Len(folder) = 0 Then Exit Sub  'User Selected Cancel
 '
 '=====================================================================================
   Option Explicit
   Private Const BIF_STATUSTEXT = &H4&
 Private Const BIF_RETURNONLYFSDIRS = 1
 Private Const BIF_DONTGOBELOWDOMAIN = 2
 Private Const MAX_PATH = 260
   Private Const WM_USER = &H400
 Private Const BFFM_INITIALIZED = 1
 Private Const BFFM_SELCHANGED = 2
 Private Const BFFM_SETSTATUSTEXT = (WM_USER + 100)
 Private Const BFFM_SETSELECTION = (WM_USER + 102)
   Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As String) As Long
 Private Declare Function SHBrowseForFolder Lib "shell32" (lpbi As BrowseInfo) As Long
 Private Declare Function SHGetPathFromIDList Lib "shell32" (ByVal pidList As Long, ByVal lpBuffer As String) As Long
 Private Declare Function lstrcat Lib "kernel32" Alias "lstrcatA" (ByVal lpString1 As String, ByVal lpString2 As String) As Long
   Private Type BrowseInfo
   hWndOwner      As Long
   pIDLRoot       As Long
   pszDisplayName As Long
   lpszTitle      As Long
   ulFlags        As Long
   lpfnCallback   As Long
   lParam         As Long
   iImage         As Long
 End Type
   Private m_CurrentDirectory As String   'The current directory
 '
   Public Function BrowseForFolder(owner As Form, Title As String, StartDir As String) As String
   'Opens a Treeview control that displays the directories in a computer
     Dim lpIDList As Long
   Dim szTitle As String
   Dim sBuffer As String
   Dim tBrowseInfo As BrowseInfo
   m_CurrentDirectory = StartDir & vbNullChar
     szTitle = Title
   With tBrowseInfo
     .hWndOwner = owner.hwnd
     .lpszTitle = lstrcat(szTitle, "" )
     .ulFlags = BIF_RETURNONLYFSDIRS + BIF_DONTGOBELOWDOMAIN + BIF_STATUSTEXT
     .lpfnCallback = GetAddressofFunction(AddressOf BrowseCallbackProc)  'get address of function.
   End With
     lpIDList = SHBrowseForFolder(tBrowseInfo)
   If (lpIDList) Then
     sBuffer = Space(MAX_PATH)
     SHGetPathFromIDList lpIDList, sBuffer
     sBuffer = Left(sBuffer, InStr(sBuffer, vbNullChar) - 1)
     BrowseForFolder = sBuffer
   Else
     BrowseForFolder = ""
   End If
     End Function
  
 Private Function BrowseCallbackProc(ByVal hwnd As Long, ByVal uMsg As Long, ByVal lp As Long, ByVal pData As Long) As Long
       Dim lpIDList As Long
   Dim ret As Long
   Dim sBuffer As String
       On Error Resume Next  'Sugested by MS to prevent an error from
                         'propagating back into the calling process.
      
   Select Case uMsg
         Case BFFM_INITIALIZED
       Call SendMessage(hwnd, BFFM_SETSELECTION, 1, m_CurrentDirectory)
             Case BFFM_SELCHANGED
       sBuffer = Space(MAX_PATH)
               ret = SHGetPathFromIDList(lp, sBuffer)
       If ret = 1 Then
         Call SendMessage(hwnd, BFFM_SETSTATUSTEXT, 0, sBuffer)
       End If
           End Select
       BrowseCallbackProc = 0
     End Function
   ' This function allows you to assign a function pointer to a vaiable.
 Private Function GetAddressofFunction(add As Long) As Long
   GetAddressofFunction = add
 End Function
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