Changing the screen resolution
A big problem for many vb-programmers is how to change the screen resolution, also
because in the Api-viewer the variable for EnumDisplaySettings and ChangeDisplaySettings
is missing!
1. Code for the basic-module 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
Example
Changes
the resolution to 640x480 with the current
colordepth. 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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