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Enumerating Windows Using the API

Enumerating Windows Using the API

API Declarations


ByVal lpEnumFunc As Long, _
ByVal lparam As Long _
) As Long

Public Declare Function IsWindowVisible Lib "user32" ( _
ByVal hwnd As Long) As Long

Public Declare Function GetWindowText Lib "user32" _
Alias "GetWindowTextA" ( _
ByVal hwnd As Long, _
ByVal lpString As String, _
ByVal cch As Long _
) As Long

Public Declare Function GetWindowTextLength Lib "user32" _
Alias "GetWindowTextLengthA" ( _
ByVal hwnd As Long _
) As Long

Public Declare Function GetClassName Lib "user32" _
Alias "GetClassNameA" ( _
ByVal hwnd As Long, _
ByVal lpClassName As String, _
ByVal nMaxCount As Long _
) As Long




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Private m_cSink As IEnumWindowsSink

Private Function EnumWindowsProc( _
    ByVal hwnd As Long, _
    ByVal lparam As Long _
  ) As Long
Dim bStop As Boolean

    bStop = False
    m_cSink.EnumWindow hwnd, bStop
    If (bStop) Then
        EnumWindowsProc = 0
    Else
        EnumWindowsProc = 1
    End If
End Function

Public Function EnumerateWindows( _
        ByRef cSink As IEnumWindowsSink _
    ) As Boolean
    If Not (m_cSink Is Nothing) Then 
        Exit Function
    End If

    Set m_cSink = cSink
    EnumWindows AddressOf EnumWindowsProc, cSink.Identifier
    Set m_cSink = Nothing

End Function

'You are now in a position to use this from any form or class. By telling the
'form/class to implement the IEnumWindowsSink methods, VB will automatically 
'put the EnumWindow sub and Identifier Property Get into the code, requiring 
'you to code them. Here is a sample showing how to find all the Windows on the 
'system from a form. The items are placed into a ListView control called 
'lvwWindows with 4 columns: 

Implements IEnumWindowsSink

Private Sub IEnumWindowsSink_EnumWindow( _
    ByVal hwnd As Long, _
    bStop As Boolean _
    )
Dim itmX As ListItem
    Set itmX = lvwWindows.ListItems.Add(, , WindowTitle(hwnd))
    itmX.SubItems(1) = ClassName(hwnd)
    itmX.SubItems(2) = hwnd
    itmX.SubItems(3) = IsWindowVisible(hwnd)

End Sub

Private Property Get IEnumWindowsSink_Identifier() As Long
    IEnumWindowsSink_Identifier = Me.hwnd
End Property

'The definitions of the functions to get a Window's title, class and 
'visibility from a hWnd are as follows: 

Public Function WindowTitle(ByVal lHwnd As Long) As String
Dim lLen As Long
Dim sBuf As String

    ' Get the Window Title:
    lLen = GetWindowTextLength(lHwnd)
    If (lLen > 0) Then
        sBuf = String$(lLen + 1, 0)
        lLen = GetWindowText(lHwnd, sBuf, lLen + 1)
        WindowTitle = Left$(sBuf, lLen)
    End If
    
End Function

Public Function ClassName(ByVal lHwnd As Long) As String
Dim lLen As Long
Dim sBuf As String
    lLen = 260
    sBuf = String$(lLen, 0)
    lLen = GetClassName(lHwnd, sBuf, lLen)
    If (lLen <> 0) Then
        ClassName = Left$(sBuf, lLen)
    End If
End Function