Attribute VB_Name = "Res"
Private Const BITSPIXEL = 12
Private Const EWX_LOGOFF = 0
Private Const EWX_SHUTDOWN = 1
Private Const EWX_REBOOT = 2
Private Const EWX_FORCE = 4
Private Const CCDEVICENAME = 32
Private Const CCFORMNAME = 32
Private Const DM_BITSPERPEL = &H40000
Private Const DM_PELSWIDTH = &H80000
Private Const DM_PELSHEIGHT = &H100000
Private Const CDS_UPDATEREGISTRY = &H1
Private Const CDS_TEST = &H4
Private Const DISP_CHANGE_SUCCESSFUL = 0
Private Const DISP_CHANGE_RESTART = 1

Private Type OldSettings
  oldWidth As Long
  oldHeight As Long
  oldDepth As Long
End Type

Private Type DEVMODE
    dmDeviceName As String * CCDEVICENAME
    dmSpecVersion As Integer
    dmDriverVersion As Integer
    dmSize As Integer
    dmDriverExtra As Integer
    dmFields As Long
    dmOrientation As Integer
    dmPaperSize As Integer
    dmPaperLength As Integer
    dmPaperWidth As Integer
    dmScale As Integer
    dmCopies As Integer
    dmDefaultSource As Integer
    dmPrintQuality As Integer
    dmColor As Integer
    dmDuplex As Integer
    dmYResolution As Integer
    dmTTOption As Integer
    dmCollate As Integer
    dmFormName As String * CCFORMNAME
    dmUnusedPadding As Integer
    dmBitsPerPel As Integer
    dmPelsWidth As Long
    dmPelsHeight As Long
    dmDisplayFlags As Long
    dmDisplayFrequency As Long
End Type

Private Declare Function GetDesktopWindow Lib "user32" () As Long
Private Declare Function GetWindowDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function EnumDisplaySettings Lib "user32" Alias "EnumDisplaySettingsA" (ByVal lpszDeviceName As Long, ByVal iModeNum As Long, lpDevMode As Any) As Boolean
Private Declare Function ChangeDisplaySettings Lib "user32" Alias "ChangeDisplaySettingsA" (lpDevMode As Any, ByVal dwFlags As Long) As Long
Private Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Long, ByVal dwReserved As Long) As Long
Private Declare Function GetDeviceCaps Lib "gdi32" (ByVal hdc As Long, ByVal nIndex As Long) As Long
Private Declare Function CreateDC Lib "gdi32" Alias "CreateDCA" (ByVal lpDriverName As String, ByVal lpDeviceName As String, ByVal lpOutput As String, ByVal lpInitData As Any) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As Long

Dim OS As OldSettings

Public Sub SaveCurrentSettings()

 With OS
  .oldWidth = Screen.Width / 15
  .oldHeight = Screen.Height / 15
  .oldDepth = GetColorDepth
 End With
 
End Sub

Public Sub RestoreOldSettings()

 ChangeRes OS.oldWidth, OS.oldHeight, OS.oldDepth
 
End Sub
Public Sub ChangeRes(X As Long, Y As Long, Bits As Long)
    Dim DevM As DEVMODE
    'Get the info into DevM
    erg& = EnumDisplaySettings(0&, 0&, DevM)
    'This is what we're going to change
    DevM.dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT Or DM_BITSPERPEL
    DevM.dmPelsWidth = X 'ScreenWidth
    DevM.dmPelsHeight = Y 'ScreenHeight
    DevM.dmBitsPerPel = Bits '(can be 8, 16, 24, 32 or even 4)
    'Now change the display and check if possible
    erg& = ChangeDisplaySettings(DevM, CDS_TEST)
    'Check if succesfull
    Select Case erg&
        Case DISP_CHANGE_RESTART
            'an = MsgBox("You've to reboot", vbYesNo + vbSystemModal, "Info")
            'If an = vbYes Then
            '    erg& = ExitWindowsEx(EWX_REBOOT, 0&)
            'End If
        Case DISP_CHANGE_SUCCESSFUL
            'erg& = ChangeDisplaySettings(DevM, CDS_UPDATEREGISTRY)
            'MsgBox "Everything's ok", vbOKOnly + vbSystemModal, "It worked!"
        Case Else
            MsgBox "Mode not supported", vbOKOnly + vbSystemModal, "Error"
    End Select
End Sub

Private Function GetColorDepth() As Long

 Dim DeskHwnd As Long
 Dim DeskDC As Long
 
 DeskHwnd = GetDesktopWindow
 DeskDC = GetWindowDC(DeskHwnd)
 GetColorDepth = GetDeviceCaps(DeskDC, BITSPIXEL)
 
End Function