VB and VBA Users Source Code: Unload all forms currently in memory
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VB/VBA Source Code
Unload all forms currently in memory
By:
Andrew Baker
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Date:
Wednesday, July 05, 2000
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1129
Category:
Windows Forms/GUI/Controls/Graphics
Article:
One of the fundamental weeknesses with many VB applications is the lack of explicit unloading of unload objects. When dealing with forms, many programmers unload every form in a project on it's termination, even if only a few of the forms are actually loaded. This will cause the forms that aren't loaded to be loaded then unloaded, which may create further complications. The following code demonstrates how to explicitly unload all the forms currently in memory and even unloads them in the correct order, which is neccessary if modal forms are present. Note, two versions of this code have been supplied, one for VBA programmers and one for VB programmers. VBA ROUTINE ----------------------- Option Explicit Private Declare Function GetActiveWindow Lib "user32" () As Long Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) As Long 'Purpose : This routine unloads all forms in memory for this project. 'Inputs : bFormsModal If True the application contains modal forms and ' hence form the topmost first 'Outputs : Returns True if all the forms where successfully unloaded. 'Author : Andrew Baker 'Date : 03/09/2000 14:17 'Notes : Function FormsSafeUnload(Optional bFormsModal As Boolean = True) As Boolean Dim lForm As Long, fForm As Object, lLoopCount As Long, lActiveWindow As Long Dim sActiveCaption As String On Error GoTo ErrFailed If bFormsModal Then 'Unload all visible forms from topmost first. 'Note: cannot loop as uses the active window lActiveWindow = GetActiveWindow Do While lActiveWindow sActiveCaption = DialogGetCaption(lActiveWindow) For lForm = VBA.UserForms.Count - 1 To 0 Step -1 If VBA.UserForms(lForm).Caption = sActiveCaption Then 'Found topmost form, unload it '(Can add break point on line below) Unload VBA.UserForms(lForm) End If Next lActiveWindow = GetActiveWindow If VBA.UserForms.Count = 0 Then Exit Do ElseIf lForm = -1 Then 'Failed to find active form '(Make sure you are not debugging this loop) Exit Do End If Loop End If 'Unload forms (including hidden forms) For Each fForm In VBA.UserForms Unload fForm Next FormsSafeUnload = (VBA.UserForms.Count = 0) Exit Function ErrFailed: FormsSafeUnload = False End Function 'Purpose : Returns the window caption of a specified window. 'Inputs : lHwnd The handle of the window to determine the caption of. 'Outputs : Returns the window caption of a specified window. 'Author : Andrew Baker 'Date : 26/02/2001 21:21 'Notes : 'Assumptions : Function DialogGetCaption(lHwnd As Long) As String Const clMaxLen As Long = 255 Dim lLen As Long, sValue As String * clMaxLen lLen = GetWindowText(lHwnd, sValue, clMaxLen) If lLen Then DialogGetCaption = Left$(sValue, lLen) End If End Function VB ROUTINE ---------- Option Explicit Private Declare Function GetActiveWindow Lib "user32" () As Long 'Purpose : This routine unloads all forms in memory for this project. 'Inputs : bFormsModal If True the application contains modal forms and ' hence form the topmost first 'Outputs : Returns True if all the forms where successfully unloaded. 'Author : Andrew Baker 'Date : 03/09/2000 14:17 'Notes : Function FormsSafeUnload(Optional bFormsModal As Boolean = True) As Boolean Dim lForm As Long, fForm As Form, lLoopCount As Long, lActiveWindow As Long On Error GoTo ErrFailed If bFormsModal Then 'Unload all visible forms from topmost first. 'Note: cannot loop as uses the active window lActiveWindow = GetActiveWindow Do While lActiveWindow For lForm = VB.Forms.Count - 1 To 0 Step -1 If VB.Forms(lForm).hWnd = lActiveWindow Then 'Found topmost form, unload it '(Can add break point on line below) Unload VB.Forms(lForm) End If Next lActiveWindow = GetActiveWindow If VB.Forms.Count = 0 Then Exit Do ElseIf lForm = -1 Then 'Failed to find active form '(Make sure you are not debugging this loop) Exit Do End If Loop End If 'Unload forms (including hidden forms) For Each fForm In VB.Forms Unload fForm Next FormsSafeUnload = (VB.Forms.Count = 0) Exit Function ErrFailed: FormsSafeUnload = False End Function
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