Introduction
This Code Shows How to detect Windows / Workstation locked & unlocked in .NET
Public Class WorkStationReader
#Region "API Calls"
Private Const DESKTOP_CREATEMENU As Int32 = &H4&
Private Const DESKTOP_CREATEWINDOW As Int32 = &H2&
Private Const DESKTOP_ENUMERATE As Int32 = &H40&
Private Const DESKTOP_HOOKCONTROL As Int32 = &H8&
Private Const DESKTOP_READOBJECTS As Int32 = &H1&
Private Const DESKTOP_SWITCHDESKTOP As Int32 = &H100&
Private Const DESKTOP_WRITEOBJECTS As Int32 = &H80&
Private Const GENERIC_WRITE As Int32 = &H40000000
Private Const HWND_BROADCAST As Int32 = &HFFFF&
Private Const WM_HOTKEY As Int32 = &H312
Private Const MOD_ALT As Int32 = &H1
Private Const MOD_CONTROL As Int32 = &H2
Private Const VK_DELETE As Int32 = &H2E
Private Const UOI_NAME As Int32 = 2
Private Declare Function OpenDesktop Lib "user32" Alias "OpenDesktopA" (ByVal lpszDesktop As String, ByVal dwFlags As Int32, ByVal fInherit As Boolean, ByVal dwDesiredAccess As Int32) As Int32
Private Declare Function CloseDesktop Lib "user32" (ByVal hDesktop As Int32) As Int32
Private Declare Function SwitchDesktop Lib "user32" (ByVal hDesktop As Int32) As Int32
#End Region
#Region "WorkStationReader Global Variables"
Dim p_lngHwnd As Int32
Dim p_lngRtn As Int32
Dim p_lngErr As Int32
Dim l_lkwkst As Int32
#End Region
#Region "WorkStationReader Events"
Event locked(ByVal ivarreturn As Object)
#End Region
#Region "WorkStationReader Functions"
Function WorkStationISLocked() As Object
Dim ivarreturn(2) As Object
p_lngHwnd = OpenDesktop("Default", 0, False, DESKTOP_SWITCHDESKTOP)
If p_lngHwnd = 0 Then
ivarreturn(0) = "Error with OpenDesktop: " & Err.LastDllError
ivarreturn(1) = False
WorkStationISLocked = ivarreturn
RaiseEvent locked(ivarreturn)
Exit Function
Else
p_lngRtn = SwitchDesktop(hDesktop:=p_lngHwnd)
p_lngErr = Err.LastDllError
If p_lngRtn = 0 Then
If p_lngErr = 0 Then
'ivarreturn(0) = "Desktop is locked: " & Err.LastDllError
ivarreturn(0) = "Locked : " '& Err.LastDllError
ivarreturn(1) = True
WorkStationISLocked = ivarreturn
RaiseEvent locked(ivarreturn)
GoTo CleanUpProc
Else
ivarreturn(0) = "Error with SwitchDesktop: " & Err.LastDllError
ivarreturn(1) = False
WorkStationISLocked = ivarreturn
GoTo CleanUpProc
End If
Else
'ivarreturn(0) = "Not locked!"
ivarreturn(0) = "Unlocked : "
ivarreturn(1) = False
WorkStationISLocked = ivarreturn
RaiseEvent locked(ivarreturn)
GoTo CleanUpProc
End If
End If
Exit Function
CleanUpProc:
p_lngHwnd = CloseDesktop(p_lngHwnd)
End Function
#End Region
End Class
