Programmers often need to know whether only a part of a window is visible. This can require a difficult calculation with coordinates. Use this routine to easily determine the visible part of your window or any control that has an hWnd property:
Option ExplicitPublic Type RECT ' Declare API type Left As Long Top As Long Right As Long Bottom As LongEnd Type' Declare API functions:Private Declare Function InvalidateRect Lib _ "user32" (ByVal hWnd As Long, lpRect As _ RECT, ByVal bErase As Long) As LongPrivate Declare Function GetUpdateRect Lib _ "user32" (ByVal hWnd As Long, lpRect As _ RECT, ByVal bErase As Long) As LongPrivate Declare Function GetClientRect Lib _ "user32" (ByVal hWnd As Long, lpRect As _ RECT) As LongPublic Function GetVisibleRect(ByVal hWnd As _ Long, lpRect As RECT) As Boolean Dim lpClientRect As RECT Call GetClientRect(hWnd, lpClientRect) Call InvalidateRect(hWnd, lpClientRect, False) GetVisibleRect = GetUpdateRect(hWnd, lpRect, _ False)End Function
