Screen Resolution Change Example Complete!

[joshuaand]

Hi,

Not sure how useful this is to anyone but I had alot of trouble finding a VB.NET Screen Resolution Change functionality, so I managed to get it working, and the code is below.

Can be called by: ChangeRes(1024,768)

Any comments are welcome, as are bug fixes!!!!

Imports System.Runtime.InteropServices
 
Public Module resChanger
 
    Const ENUM_CURRENT_SETTINGS As Integer = -1
    Const CDS_UPDATEREGISTRY As Integer = &H1
    Const CDS_TEST As Long = &H2
 
    Const CCDEVICENAME As Integer = 32
    Const CCFORMNAME As Integer = 32
 
    Const DISP_CHANGE_SUCCESSFUL As Integer = 0
    Const DISP_CHANGE_RESTART As Integer = 1
    Const DISP_CHANGE_FAILED As Integer = -1
 
    Private Declare Function EnumDisplaySettings Lib "user32" Alias "EnumDisplaySettingsA" (ByVal lpszDeviceName As Integer, ByVal iModeNum As Integer, ByRef lpDevMode As DEVMODE) As Integer
    Private Declare Function ChangeDisplaySettings Lib "user32" Alias "ChangeDisplaySettingsA" (ByRef DEVMODE As DEVMODE, ByVal flags As Long) As Integer
 
    <StructLayout(LayoutKind.Sequential)> Public Structure DEVMODE
        <MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst:=CCDEVICENAME)> Public dmDeviceName As String
        Public dmSpecVersion As Short
        Public dmDriverVersion As Short
        Public dmSize As Short
        Public dmDriverExtra As Short
        Public dmFields As Integer
        Public dmOrientation As Short
        Public dmPaperSize As Short
        Public dmPaperLength As Short
        Public dmPaperWidth As Short
        Public dmScale As Short
        Public dmCopies As Short
        Public dmDefaultSource As Short
        Public dmPrintQuality As Short
        Public dmColor As Short
        Public dmDuplex As Short
        Public dmYResolution As Short
        Public dmTTOption As Short
        Public dmCollate As Short
        <MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst:=CCFORMNAME)> Public dmFormName As String
        Public dmUnusedPadding As Short
        Public dmBitsPerPel As Short
        Public dmPelsWidth As Integer
        Public dmPelsHeight As Integer
        Public dmDisplayFlags As Integer
        Public dmDisplayFrequency As Integer
    End Structure
 
    Public Sub changeRes(ByVal theWidth As Integer, ByVal theHeight As Integer)
 
        Dim DevM As DEVMODE
 
        DevM.dmDeviceName = New [String](New Char(32) {})
        DevM.dmFormName = New [String](New Char(32) {})
        DevM.dmSize = CShort(Marshal.SizeOf(GetType(DEVMODE)))
 
 
        If 0 <> EnumDisplaySettings(Nothing, ENUM_CURRENT_SETTINGS, DevM) Then
            Dim lResult As Integer
 
            DevM.dmPelsWidth = theWidth
            DevM.dmPelsHeight = theHeight
            DevM.dmPelsWidth = 1280
            DevM.dmPelsHeight = 1024
 
            lResult = ChangeDisplaySettings(DevM, CDS_TEST)
 
            If lResult = DISP_CHANGE_FAILED Then
                MsgBox("Display Change Failed.", MsgBoxStyle.OKOnly + MsgBoxStyle.Critical, "Screen Resolution Change Failed")
            Else
 
                lResult = ChangeDisplaySettings(DevM, CDS_UPDATEREGISTRY)
 
                Select Case lResult
                    Case DISP_CHANGE_RESTART
                        MsgBox("You must restart your computer to apply these changes.", MsgBoxStyle.OKOnly + MsgBoxStyle.Critical, "Screen Resolution Has Changed")
                    Case DISP_CHANGE_SUCCESSFUL
                        MsgBox("Display Change Successful.", MsgBoxStyle.OKOnly + MsgBoxStyle.Information, "Screen Resolution Successful")
                    Case Else
                        MsgBox("Display Change Failed.", MsgBoxStyle.OKOnly + MsgBoxStyle.Critical, "Screen Resolution Change Failed")
                End Select
            End If
 
 
        End If
    End Sub
 
End Module

[wordracr]

Wonderful code!

I just added some opt parameters that force the change to be... more smoother. (I hate when it's 60 Hertz and I can the monitor moving :P)

Public Sub Main()
        MessageBox.Show(changeRes(1280, 1024).ToString)
    End Sub
 
 
    Public Function changeRes(ByVal theWidth As Integer, ByVal theHeight As Integer, _
        Optional ByVal theFrequency As Integer = 85, Optional ByVal theBitDepth As Integer = 32) As Boolean
 
        Dim DevM As DEVMODE
 
        DevM.dmDeviceName = New [String](New Char(32) {})
        DevM.dmFormName = New [String](New Char(32) {})
        DevM.dmSize = CShort(Marshal.SizeOf(GetType(DEVMODE)))
 
 
        If 0 <> EnumDisplaySettings(Nothing, ENUM_CURRENT_SETTINGS, DevM) Then
            Dim lResult As Integer
 
            DevM.dmPelsWidth = theWidth
            DevM.dmPelsHeight = theHeight
            DevM.dmBitsPerPel = theBitDepth
            DevM.dmDisplayFrequency = theFrequency
 
            lResult = ChangeDisplaySettings(DevM, CDS_TEST)
 
            If lResult = DISP_CHANGE_FAILED Then
                Return False
            Else
 
                lResult = ChangeDisplaySettings(DevM, CDS_UPDATEREGISTRY)
 
                Select Case lResult
                    Case DISP_CHANGE_RESTART
                        Return False
                    Case DISP_CHANGE_SUCCESSFUL
                        Return True
                    Case Else
                        Return False
                End Select
 
            End If
 
 
        End If
    End Function

[AeroII]

SWEET! Just what ive been looking for. Just wondering, but how can i make it so it changes back to the original resolution on form close?

[SuperSparks]

Be aware that changing the screen resolution of a monitor can seriously mess up the display on any other monitors in a dual-monitor or multi-monitor setup. You can really annoy some people by doing that sort of thing - I'd probably be one of them!. Just because you can do something doesn't necessarily mean that you should

[Asgorath]

The code doesn't work i get a change sucessful but no changes on resolution... Anyway if a sold/distributed an application i would put Minimum Resolution 1024x768(for example) on the system requirement section