Visual Basic Programming Code Examples

Visual Basic > Forms Code Examples

Return a dialog handle-class name from a caption

Return a dialog handle-class name from a caption

Most form related API calls require a window handle and unfortunately VBA doesn't provide these. The following routines will return both a forms window handle and it's class name from the forms caption.

Private Declare Function FindWindowA Lib "user32" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long


'Purpose   :    Returns the Windows Handle of a Dialog based on its caption.
'Inputs    :    sDialogCaption                  The dialog caption.
'               [sClassName]                    The class name of the dialog. If unknown, do not specify
'                                               this parameter.
'Outputs   :    The Dialogs Window Handle
'Notes     :    1/  Find windows scans down the Z Order of the dialogs currently displayed,
'               2/  To Call in a VBA form use:      lHwnd = DialogGetHwnd(Me.Caption)
'               3/  Class names:
'                   "bosa_sdm_XL"           Excel 5 Form class name
'                   "ThunderDFrame"         Excel 97/2000 Form class name
'               4/  Use Spy ++ (comes with Visual Studio), OR the function DialogGetClassName to
'                   return the class names of forms.
'Revisions :

Function DialogGetHwnd(ByVal sDialogCaption As String, Optional sClassName As String = vbNullString) As Long
    On Error Resume Next
    DialogGetHwnd = FindWindowA(sClassName, sDialogCaption)
    On Error GoTo 0
End Function


'Purpose     :  Returns the class name of a object given the handle or caption
'Inputs      :  [sCaption]      =       The objects caption
'               [lHwnd]         =       The objects handle
'Outputs     :
'Notes       :  Pass in either sCaption OR lHwnd, to get a class name


Function DialogGetClassName(Optional sCaption As String, Optional lHwnd As Long) As String
    Const clMaxLen As Long = 256
    Dim lRetVal As Long, sResult As String * clMaxLen
    
    If Len(sCaption) Then
        'Get Dialog Handle
        lHwnd = DialogGetHwnd(sCaption)
    End If
    If lHwnd Then
        'Get Class Name
        lRetVal = GetClassName(lHwnd, sResult, clMaxLen)
        DialogGetClassName = Left$(sResult, lRetVal)
    End If
End Function