Snippet Library

Declare Function EnumDisplaySettings Lib "user32" _ 
Alias "EnumDisplaySettingsA" _ 
(ByVal lpszDeviceName As Long, _ 
ByVal iModeNum As Long, _ 
lpDevMode As Any) As Boolean 
Declare Function ChangeDisplaySettings Lib "user32" _ 
Alias "ChangeDisplaySettingsA" _ 
(lpDevMode As Any, ByVal dwFlags As Long) As Long 

Declare Function ExitWindowsEx Lib "user32" _ 
(ByVal uFlags As Long, ByVal dwReserved As Long) As Long 
Public Const EWX_LOGOFF = 0 
Public Const EWX_SHUTDOWN = 1 
Public Const EWX_REBOOT = 2 
Public Const EWX_FORCE = 4 
Public Const CCDEVICENAME = 32 
Public Const CCFORMNAME = 32 
Public Const DM_BITSPERPEL = &H40000 
Public Const DM_PELSWIDTH = &H80000 
Public Const DM_PELSHEIGHT = &H100000 
Public Const CDS_UPDATEREGISTRY = &H1 
Public Const CDS_TEST = &H4 
Public Const DISP_CHANGE_SUCCESSFUL = 0 
Public Const DISP_CHANGE_RESTART = 1 
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

'And..... 

Dim DevM As DEVMODE 
'Get the info into DevM 
erg& = EnumDisplaySettings(0&, 0&, DevM) 
'We don't change the colordepth, because a 
'rebot will be necessary 

DevM.dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT 'Or DM_BITSPERPEL 
DevM.dmPelsWidth = 640 'ScreenWidth 
DevM.dmPelsHeight = 480 'ScreenHeight 
'DevM.dmBitsPerPel = 32 (could be 8, 16, 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 
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