Bir 32-bit VB uygulamasý birden çok örneðini engelleme

Adým adým örnek

1. Yeni bir Visual Basic projesi oluþturun.
2. Proje Özellikleri gidin ve Sub Main için baþlangýç nesneyi (veya baþlangýç formu olarak VB4) ayarlayýn.
   
3. Standart modül projeye ekleyin.
4. Aþaðýdaki kodu modüle yapýþtýrýn:
   

         Option Explicit
   
         Public Const GW_HWNDPREV = 3
   
         Declare Function OpenIcon Lib "user32" (ByVal hwnd As Long) As Long
         Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
           (ByVal lpClassName As String, ByVal lpWindowName As String) _
            As Long
         Declare Function GetWindow Lib "user32" _
           (ByVal hwnd As Long, ByVal wCmd As Long) As Long
         Declare Function SetForegroundWindow Lib "user32" _
           (ByVal hwnd As Long) As Long
   
         Private Sub Form_Load()
               If App.PrevInstance Then
                  ActivatePrevInstance
               End If
            End Sub
   
         Sub ActivatePrevInstance()
            Dim OldTitle As String
            Dim PrevHndl As Long
            Dim result As Long
   
            'Save the title of the application.
            OldTitle = App.Title
   
            'Rename the title of this application so FindWindow
            'will not find this application instance.
            App.Title = "unwanted instance"
   
            'Attempt to get window handle using VB4 class name.
            PrevHndl = FindWindow("ThunderRTMain", OldTitle)
   
            'Check for no success.
            If PrevHndl = 0 Then
               'Attempt to get window handle using VB5 class name.
               PrevHndl = FindWindow("ThunderRT5Main", OldTitle)
            End If
   
            'Check if found
            If PrevHndl = 0 Then
            'Attempt to get window handle using VB6 class name
            PrevHndl = FindWindow("ThunderRT6Main", OldTitle)
            End If
   
            'Check if found
            If PrevHndl = 0 Then
               'No previous instance found.
               Exit Sub
            End If
   
            'Get handle to previous window.
            PrevHndl = GetWindow(PrevHndl, GW_HWNDPREV)
   
            'Restore the program.
            result = OpenIcon(PrevHndl)
   
            'Activate the application.
            result = SetForegroundWindow(PrevHndl)
   
            'End the application.
            Unload Me
         End Sub
   
   						

5. Projeyi bir EXE içinde derleyin.
6. Visual Basic çýkýn.
7. Oluþturduðunuz bir yürütülebilir dosyayý çalýþtýrýn.
8. 7. Adýmý yineleyin.
   
   Sonuç: Odaðý program ilk örneðini verilir ve ikinci örneði kapatýldý. Ilk uygulama örneðinin küçülttüyseniz, normal bir pencerede otomatik olarak geri yüklenecektir.

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