ACC2: How to Detect When MS Access Is Activated or Deactivated

• Microsoft Access version 2.0

SUMMARY

Advanced: Requires expert coding, interoperability, and multiuser skills.

This article describes how to detect and run code when Microsoft Access is activated or deactivated. Switching to Microsoft Access from another application activates Microsoft Access, and switching from Microsoft Access to another application deactivates Microsoft Access.

This article assumes that you are familiar with Access Basic and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Access Basic, please refer to the "Building Applications" manual.

MORE INFORMATION

The following steps demonstrate how to create a form called Access_Activation that will detect when Microsoft Access is activated or deactivated. The form contains two empty procedures called Access_Activate and Access_Deactivate into which you can insert the code you want to run when Microsoft Access is activated or deactivated. When the Access_Activation form is open in Form view, switching to Microsoft Access from another application will cause the Access_Activate procedure to run. Switching from Microsoft Access to another application will cause the Access_Deactivate procedure to run.

The Access_Activation form must be open in order to detect when Microsoft Access is activated and deactivated. To make sure the form is always open, you could open the form in a hidden state in your database's Autoexec macro. To open the form in a hidden state, set the Window Mode argument of the OpenForm macro action to Hidden.

1. Open any database and create a blank new form. Set the following properties for the form:

         OnTimer: [Event Procedure]
         TimerInterval: 500
   

2. From the View menu, choose Code. Type the following lines in the form module's Declarations section.

   NOTE: In the following sample code, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this code in Access Basic.

         Option Explicit
         Declare Function GetActiveWindow Lib "User" () As Integer
         Declare Function GetParent Lib "User" (ByVal hWnd As Integer) _
         As Integer
         Declare Function GetFocus Lib "User" () As Integer
   

3. Enter the following code for the OnTimer property event procedure:

         Sub Form_Timer ()
            Dim RetVal As Integer
            Dim CurrhWnd As Integer
            Dim AccesshWnd As Integer
            Static ActiveApphWnd As Integer
   
            ' Get the Microsoft Access window handle (hWnd).
            AccesshWnd = GetAccesshWnd()
   
            ' Get the active application window handle (hWnd).
            CurrhWnd = GetActiveApphWnd()
   
            ' The first time through, just record the current
            ' window handle.
            If ActiveApphWnd = 0 Then
               ActiveApphWnd = CurrhWnd
               Exit Sub
            End If
   
            ' Determine if the current window handle differs from the
            ' previous window handle (focus change).
            If CurrhWnd <> ActiveApphWnd Then
               ' Record the current window handle.
               ActiveApphWnd = CurrhWnd
   
               ' Determine if the current handle is the Microsoft Access
               ' handle (activate Microsoft Access?).
               If ActiveApphWnd = AccesshWnd Then
                  Access_Activate
               Else
                  Access_Deactivate
               End If
            End If
         End Sub
   
   

4. Enter the following procedures in the form module:

         Sub Access_Activate ()
            ' Insert the code that you want to run when Microsoft Access
            ' is activated here.
         End Sub
   
         Sub Access_Deactivate ()
            ' Insert the code that you want to run when Microsoft Access
            ' is deactivated here.
         End Sub
   
         Function GetAccesshWnd ()
            GetAccesshWnd = GetTopMosthWnd(Me.hWnd)
         End Function
   
         Function GetActiveApphWnd ()
            GetActiveApphWnd = GetTopMosthWnd(GetActiveWindow())
         End Function
   
         Function GetTopMosthWnd (ByVal hWnd)
            Dim hWndTopMost As Integer
            hWndTopMost = hWnd
   
            ' Find the top window without a parent window.
            While hWnd <> 0
               hWndTopMost = hWnd
               hWnd = GetParent(hWnd)
            Wend
   
            GetTopMosthWnd = hWndTopMost
         End Function
   
   

5. Close the module and save the form as Access_Activation.

How to Use the Access_Activation Form

The following steps demonstrate how to use the Access_Activation form:

1. Open any database and create the Access_Activation form as described above.

2. Substitute the following Access_Activate procedure for the Access_Activate procedure you created in step 4 above:

         Sub Access_Activate ()
            MsgBox "Microsoft Access was activated"
         End Sub
   
   

3. View the Access_Activation form in Form view.

4. Press ALT+TAB to switch from Microsoft Access to another application.

5. Press ALT+TAB to switch back to Microsoft Access. A message box with the text "Microsoft Access was activated" is displayed.

REFERENCES