How To Enumerate Windows Using the WIN32 API (183009)

MORE INFORMATION

Step-by-Step Example

1. Start a new project in Visual Basic. Form1 is created by default.
2. Add two CommandButtons and a TextBox.
3. Copy the following code into the Form's module:

         Option Explicit
   
         Private Sub Command1_Click()
            Dim lRet As Long, lParam As Long
            Dim lhWnd As Long
   
            lhWnd = Me.hwnd  ' Find the Form's Child Windows
            ' Comment the line above and uncomment the line below to
            ' enumerate Windows for the DeskTop rather than for the Form
            'lhWnd = GetDesktopWindow()  ' Find the Desktop's Child Windows
            ' enumerate the list
            lRet = EnumChildWindows(lhWnd, AddressOf EnumChildProc, lParam)
         End Sub
   
         Private Sub Command2_Click()
            Dim lRet As Long
            Dim lParam As Long
   
            'enumerate the list
            lRet = EnumWindows(AddressOf EnumWinProc, lParam)
            ' How many Windows did we find?
            Debug.Print TopCount; " Total Top level Windows"
            Debug.Print ChildCount; " Total Child Windows"
            Debug.Print ThreadCount; " Total Thread Windows"
            Debug.Print "For a grand total of "; TopCount + _
            ChildCount + ThreadCount; " Windows!"
         End Sub
   					

4. Add a Module with the following code:

         Option Explicit
   
         Type RECT
            Left As Long
            Top As Long
            Right As Long
            Bottom As Long
         End Type
   
         Declare Function GetWindowRect Lib "user32" (ByVal hwnd As Long, _
            lpRect As RECT) As Long
   
         Declare Function MoveWindow Lib "user32" (ByVal hwnd As Long, _
            ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, _
            ByVal nHeight As Long, ByVal bRepaint As Long) As Long
   
         Declare Function GetDesktopWindow Lib "user32" () As Long
   
         Declare Function EnumWindows Lib "user32" _
            (ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
   
         Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent _
            As Long, ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
   
         Declare Function EnumThreadWindows Lib "user32" (ByVal dwThreadId _
            As Long, ByVal lpfn As Long, ByVal lParam As Long) As Long
   
         Declare Function GetWindowThreadProcessId Lib "user32" _
            (ByVal hwnd As Long, lpdwProcessId As Long) As Long
   
         Declare Function GetClassName Lib "user32" Alias "GetClassNameA" _
            (ByVal hwnd As Long, ByVal lpClassName As String, _
            ByVal nMaxCount As Long) As Long
   
         Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" _
            (ByVal hwnd As Long, ByVal lpString As String, _
            ByVal cch As Long) As Long
   
         Public TopCount As Integer     ' Number of Top level Windows
         Public ChildCount As Integer   ' Number of Child Windows
         Public ThreadCount As Integer  ' Number of Thread Windows
   
         Function EnumWinProc(ByVal lhWnd As Long, ByVal lParam As Long) _
            As Long
            Dim RetVal As Long, ProcessID As Long, ThreadID As Long
            Dim WinClassBuf As String * 255, WinTitleBuf As String * 255
            Dim WinClass As String, WinTitle As String
   
            RetVal = GetClassName(lhWnd, WinClassBuf, 255)
            WinClass = StripNulls(WinClassBuf)  ' remove extra Nulls & spaces
            RetVal = GetWindowText(lhWnd, WinTitleBuf, 255)
            WinTitle = StripNulls(WinTitleBuf)
            TopCount = TopCount + 1
            ' see the Windows Class and Title for each top level Window
            Debug.Print "Top level Class = "; WinClass; ", Title = "; WinTitle
            ' Usually either enumerate Child or Thread Windows, not both.
            ' In this example, EnumThreadWindows may produce a very long list!
            RetVal = EnumChildWindows(lhWnd, AddressOf EnumChildProc, lParam)
            ThreadID = GetWindowThreadProcessId(lhWnd, ProcessID)
            RetVal = EnumThreadWindows(ThreadID, AddressOf EnumThreadProc, _
            lParam)
            EnumWinProc = True
         End Function
   
         Function EnumChildProc(ByVal lhWnd As Long, ByVal lParam As Long) _
            As Long
            Dim RetVal As Long
            Dim WinClassBuf As String * 255, WinTitleBuf As String * 255
            Dim WinClass As String, WinTitle As String
            Dim WinRect As RECT
            Dim WinWidth As Long, WinHeight As Long
   
            RetVal = GetClassName(lhWnd, WinClassBuf, 255)
            WinClass = StripNulls(WinClassBuf)  ' remove extra Nulls & spaces
            RetVal = GetWindowText(lhWnd, WinTitleBuf, 255)
            WinTitle = StripNulls(WinTitleBuf)
            ChildCount = ChildCount + 1
            ' see the Windows Class and Title for each Child Window enumerated
            Debug.Print "   Child Class = "; WinClass; ", Title = "; WinTitle
            ' You can find any type of Window by searching for its WinClass
            If WinClass = "ThunderTextBox" Then    ' TextBox Window
               RetVal = GetWindowRect(lhWnd, WinRect)  ' get current size
               WinWidth = WinRect.Right - WinRect.Left ' keep current width
               WinHeight = (WinRect.Bottom - WinRect.Top) * 2 ' double height
               RetVal = MoveWindow(lhWnd, 0, 0, WinWidth, WinHeight, True)
               EnumChildProc = False
            Else
               EnumChildProc = True
            End If
         End Function
   
         Function EnumThreadProc(ByVal lhWnd As Long, ByVal lParam As Long) _
            As Long
            Dim RetVal As Long
            Dim WinClassBuf As String * 255, WinTitleBuf As String * 255
            Dim WinClass As String, WinTitle As String
   
            RetVal = GetClassName(lhWnd, WinClassBuf, 255)
            WinClass = StripNulls(WinClassBuf)  ' remove extra Nulls & spaces
            RetVal = GetWindowText(lhWnd, WinTitleBuf, 255)
            WinTitle = StripNulls(WinTitleBuf)
            ThreadCount = ThreadCount + 1
            ' see the Windows Class and Title for top level Window
            Debug.Print "Thread Window Class = "; WinClass; ", Title = "; _
            WinTitle
            EnumThreadProc = True
         End Function
   
         Public Function StripNulls(OriginalStr As String) As String
            ' This removes the extra Nulls so String comparisons will work
            If (InStr(OriginalStr, Chr(0)) > 0) Then
               OriginalStr = Left(OriginalStr, InStr(OriginalStr, Chr(0)) - 1)
            End If
            StripNulls = OriginalStr
         End Function
   
   					

5. Run the project and click on Command1. This enumerates the Form's child Windows until it finds the TextBox, then doubles the height of the TextBox and moves it to position 0, 0 (upper-left of the Form.)
6. Click on Command2. It now lists the Class and Title (if there is one) for all top-level Windows, for their Child Windows, and any non-child Windows associated with their threads, to the Immediate Window. Note that this can be a very long list and may take a minute to complete.
7. From the Run Menu, choose End, or click the END button to stop the program. Change the code in Sub Command1_Click according to the comments to pass the handle from GetDesktopWindow. Run the project and click on Command1 to enumerate all child Windows of the DeskTop. Note that this procedure can take some time to complete.