Chaning screen resolutions from VB.Net application

2010-11-08

Question

_{Monday, November 8, 2010 3:15 PM}

Hi,

I need to change screen resolutions using my application.

How to:

1) Read current resolution

2) Changing it using my application and then returning to current on exit.

Thanks

Furqan

All replies (2)

_{Monday, November 8, 2010 3:39 PM ✅Answered | 1 vote}

You can get the current resolution using the Screen class. The following assumes it is the primary display you are interested in:

Dim height As Integer = Screen.PrimaryScreen.Bounds.Height
Dim width As Integer = Screen.PrimaryScreen.Bounds.Width

Changing the resolution is more difficult. This CodeProject describes how to do it in C# http://www.codeproject.com/KB/dotnet/changing-display-settings.aspx and you can use this following website to help you translate the C# code to VB http://www.developerfusion.com/tools/convert/csharp-to-vb/

To change the resolution back before you exit, save the initial resolution before you change it, and restore it in your main form's closing event.

_{Tuesday, November 9, 2010 4:39 PM ✅Answered | 1 vote}

First, I want to say that changing the resolution in somebody computer is usualy not welcome and you should avoid that as mich as possible. You should resize your control and font instead.

However, if you realy need to do it here the code

The example gives you a class that change the resolution ant that return "Success/fail/restart/notsupported" to give the result of the resolution change attempt.

Fail: means that the resolution was not changed.. Either the registery could not be updated or the driver returned an error

ResolutionNotSupported: Means the resolution value passed as argument to the function represente a resolution not supported by the system

Restart: Means that this system need to be restarted for the new resolution to be active. This will always be if the windows version is 9x. And it may also comes on some XP, Vista, Windows7 system (Usualy laptop system). If you have changed the resolution and had a "Restart" result, if you change the resolution again before the system was restarted, you will get as result "Success". But even if the result is success, the resolution will not change before you restart the system.

Success: Means that the resolution was probably changed successfuly. But this result is not an absolute guaranty that the resolution change was successful, it only means that the registery was updated and that the driver did not return an error. But a lot of system are using some generic driver that are not perfectly adapted to recognize if the graphic hardware or the screen can actualy render this resolution successfuly

Here is the code: ( I added to the class a short example to show the usage of the class )

Public Class Form1

  Private Resolution As New ResolutionChanger
  Private OldWidth As UInteger
  Private OldHeight As UInteger

  Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
    Resolution.SetResolution(OldWidth, OldHeight)
  End Sub

  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    OldHeight = CUInt(Screen.PrimaryScreen.Bounds.Height)
    OldWidth = CUInt(Screen.PrimaryScreen.Bounds.Width)
    Select Case Resolution.SetResolution(800, 600)
      Case ResolutionChanger.ChangeResult.Success
        MsgBox("The Resolution was changed", MsgBoxStyle.OkOnly)
      Case ResolutionChanger.ChangeResult.Restart
        MsgBox("Restart your system to activate the new resolution setting", MsgBoxStyle.OkOnly)
      Case ResolutionChanger.ChangeResult.Fail
        MsgBox("The resolution couldn't be changed", MsgBoxStyle.OkOnly)
      Case ResolutionChanger.ChangeResult.ResolutionNotSupported
        MsgBox("The requested resolution is not supported by your system", MsgBoxStyle.OkOnly)
    End Select
  End Sub

End Class
'
'========== RESOLUTION CHANGER ===============================
'
'
Class ResolutionChanger
  Public Enum ChangeResult
    Success
    Restart
    Fail
    ResolutionNotSupported
  End Enum

  Public Function SetResolution(ByVal Width As UInteger, ByVal Height As UInteger) As ChangeResult
    Dim DevMode As New DEVMODEA
    If User_32.EnumDisplaySettingsA(Screen.PrimaryScreen.DeviceName, ENUM_CURRENT_SETTINGS, DevMode) Then
      DevMode.dmPelsWidth = Width
      DevMode.dmPelsHeight = Height
      Dim ReturnValue = User_32.ChangeDisplaySettingsA(DevMode, CDS_TEST)
      If ReturnValue = DISP_CHANGE_FAILED Then
        'The Requested resolution is not supported by the system
        Return ChangeResult.ResolutionNotSupported
      Else
        ReturnValue = User_32.ChangeDisplaySettingsA(DevMode, CDS_UPDATEREGISTRY)
        Select Case ReturnValue
          Case DISP_CHANGE_RESTART
            'The resolution cannot be change dynamically on every system
            'Windows 9x and some Laptop (XP,Vista,Windows7) have to reboot.
            Return ChangeResult.Restart
          Case DISP_CHANGE_SUCCESSFUL
            'Resolution was changed
            'This is not an assurance that the new resolution will render 
            'proprely on every system. It only means that the registery was
            'updated succesfuly and that the driver have not return any
            'error
            Return ChangeResult.Success
          Case Else
            'An error has caused the resolution not to be changed
            Return ChangeResult.Fail
        End Select
      End If
    End If
  End Function
  '
  '============Region Interop ==============================================
  '
  '
  Private Const ENUM_CURRENT_SETTINGS As Integer = -1
  Private Const CDS_UPDATEREGISTRY As Integer = 1
  Private Const CDS_TEST As Integer = 2
  Private Const DISP_CHANGE_SUCCESSFUL As Integer = 0
  Private Const DISP_CHANGE_RESTART As Integer = 1
  Private Const DISP_CHANGE_FAILED As Integer = -1

  <System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)> _
  Public Structure DEVMODEA
    'BYTE[32]
    <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValArray, SizeConst:=32, ArraySubType:=System.Runtime.InteropServices.UnmanagedType.I1)> _
    Public dmDeviceName() As Byte
    Public dmSpecVersion As UShort
    Public dmDriverVersion As UShort
    Public dmSize As UShort
    Public dmDriverExtra As UShort
    Public dmFields As UInteger
    Public Union1 As Anonymous_2338c0fc_03a3_4514_b536_fb9bb5df14c5
    Public dmColor As Short
    Public dmDuplex As Short
    Public dmYResolution As Short
    Public dmTTOption As Short
    Public dmCollate As Short
    <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValArray, SizeConst:=32, ArraySubType:=System.Runtime.InteropServices.UnmanagedType.I1)> _
    Public dmFormName() As Byte
    Public dmLogPixels As UShort
    Public dmBitsPerPel As UInteger
    Public dmPelsWidth As UInteger
    Public dmPelsHeight As UInteger
    Public Union2 As Anonymous_7557e508_845c_4777_b9f2_a1496c1c7b21
    Public dmDisplayFrequency As UInteger
    Public dmICMMethod As UInteger
    Public dmICMIntent As UInteger
    Public dmMediaType As UInteger
    Public dmDitherType As UInteger
    Public dmReserved1 As UInteger
    Public dmReserved2 As UInteger
    Public dmPanningWidth As UInteger
    Public dmPanningHeight As UInteger
  End Structure

  <System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Explicit)> _
  Public Structure Anonymous_2338c0fc_03a3_4514_b536_fb9bb5df14c5
    <System.Runtime.InteropServices.FieldOffsetAttribute(0)> _
    Public Struct1 As Anonymous_a67d541d_da92_408e_8852_89977e56cead
    <System.Runtime.InteropServices.FieldOffsetAttribute(0)> _
    Public Struct2 As Anonymous_d973d7e7_ad4c_4155_86fe_6d2b51ab5f04
  End Structure

  <System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Explicit)> _
  Public Structure Anonymous_7557e508_845c_4777_b9f2_a1496c1c7b21
    <System.Runtime.InteropServices.FieldOffsetAttribute(0)> _
    Public dmDisplayFlags As UInteger
    <System.Runtime.InteropServices.FieldOffsetAttribute(0)> _
    Public dmNup As UInteger
  End Structure

  <System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)> _
  Public Structure Anonymous_a67d541d_da92_408e_8852_89977e56cead
    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
  End Structure

  <System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)> _
  Public Structure Anonymous_d973d7e7_ad4c_4155_86fe_6d2b51ab5f04
    Public dmPosition As POINTL
    Public dmDisplayOrientation As UInteger
    Public dmDisplayFixedOutput As UInteger
  End Structure

  <System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)> _
  Public Structure POINTL
    Public x As Integer
    Public y As Integer
  End Structure

  Partial Public Class User_32
    <System.Runtime.InteropServices.DllImportAttribute("user32.dll", EntryPoint:="EnumDisplaySettingsA")> _
    Public Shared Function EnumDisplaySettingsA(<System.Runtime.InteropServices.InAttribute(), System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPStr)> ByVal lpszDeviceName As String, ByVal iModeNum As Integer, <System.Runtime.InteropServices.OutAttribute()> ByRef lpDevMode As DEVMODEA) As <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.Bool)> Boolean
    End Function

    <System.Runtime.InteropServices.DllImportAttribute("user32.dll", EntryPoint:="ChangeDisplaySettingsA")> _
    Public Shared Function ChangeDisplaySettingsA(<System.Runtime.InteropServices.OutAttribute()> ByRef lpDevMode As DEVMODEA, ByVal dwFlags As UInteger) As Integer
    End Function
  End Class

End Class

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Chaning screen resolutions from VB.Net application

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