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Change screen resolution from vb.net Application

Hi All,
I need to change the screen resolution from my vb.net application.
I have some code in vb.net which change the resolution but the task bar change its place
and go to middle of screen when the resolution is changed to 1024x768.
Any help on correcting the code or another example code will be appreciated.
The code is given below,
Add a module and add this code,
Option Strict Off
Option Explicit On
Module Module1

      Public Const EWX_LOGOFF As Short = 0
      Public Const EWX_SHUTDOWN As Short = 1
      Public Const EWX_REBOOT As Short = 2
      Public Const EWX_FORCE As Short = 4
      Public Const CCDEVICENAME As Short = 32
      Public Const CCFORMNAME As Short = 32
      Public Const DM_BITSPERPEL As Integer = &H40000
      Public Const DM_PELSWIDTH As Integer = &H80000
      Public Const DM_PELSHEIGHT As Integer = &H100000
      Public Const CDS_UPDATEREGISTRY As Short = &H1s
      Public Const CDS_TEST As Short = &H4s
      Public Const DISP_CHANGE_SUCCESSFUL As Short = 0
      Public Const DISP_CHANGE_RESTART As Short = 1

      Structure DEVMODE
            <VBFixedString(CCDEVICENAME),System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValTStr,SizeConst:=CCDEVICENAME)> Public dmDeviceName As String
            Dim dmSpecVersion As Short
            Dim dmDriverVersion As Short
            Dim dmSize As Short
            Dim dmDriverExtra As Short
            Dim dmFields As Integer
            Dim dmOrientation As Short
            Dim dmPaperSize As Short
            Dim dmPaperLength As Short
            Dim dmPaperWidth As Short
            Dim dmScale As Short
            Dim dmCopies As Short
            Dim dmDefaultSource As Short
            Dim dmPrintQuality As Short
            Dim dmColor As Short
            Dim dmDuplex As Short
            Dim dmYResolution As Short
            Dim dmTTOption As Short
            Dim dmCollate As Short
            <VBFixedString(CCFORMNAME),System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValTStr,SizeConst:=CCFORMNAME)> Public dmFormName As String
            Dim dmUnusedPadding As Short
            Dim dmBitsPerPel As Short
            Dim dmPelsWidth As Integer
            Dim dmPelsHeight As Integer
            Dim dmDisplayFlags As Integer
            Dim dmDisplayFrequency As Integer
      End Structure

Declare Function EnumDisplaySettings Lib "user32" Alias "EnumDisplaySettingsA" (ByVal lpszDeviceName As Integer, ByVal iModeNum As Integer, ByRef lpDevMode As DEVMODE) As Boolean
Declare Function ChangeDisplaySettings Lib "user32" Alias "ChangeDisplaySettingsA" (ByRef lpDevMode As DEVMODE, ByVal dwFlags As Integer) As Integer
Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Integer, ByVal dwReserved As Integer) As Integer
End Module
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
And the form code is
Option Strict Off
Option Explicit On
Friend Class Form1
Inherits System.Windows.Forms.Form
#Region "Windows Form Designer generated code "
Public Sub New()
MyBase.New()

'This call is required by the Windows Form Designer.
InitializeComponent()
End Sub
'Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal Disposing As Boolean)
If Disposing Then
If Not components Is Nothing Then
components.Dispose()
End If
End If
MyBase.Dispose(Disposing)
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer
Public ToolTip1 As System.Windows.Forms.ToolTip
Public WithEvents _optRes_2 As System.Windows.Forms.RadioButton
Public WithEvents _optRes_1 As System.Windows.Forms.RadioButton
Public WithEvents _optRes_0 As System.Windows.Forms.RadioButton
Public WithEvents cmdChange As System.Windows.Forms.Button
Public WithEvents optRes As Microsoft.VisualBasic.Compatibility.VB6.RadioButtonArray
Public WithEvents optShut As Microsoft.VisualBasic.Compatibility.VB6.RadioButtonArray
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.components = New System.ComponentModel.Container
Me.ToolTip1 = New System.Windows.Forms.ToolTip(Me.components)
Me._optRes_2 = New System.Windows.Forms.RadioButton
Me._optRes_1 = New System.Windows.Forms.RadioButton
Me._optRes_0 = New System.Windows.Forms.RadioButton
Me.cmdChange = New System.Windows.Forms.Button
Me.optRes = New Microsoft.VisualBasic.Compatibility.VB6.RadioButtonArray(Me.components)
Me.optShut = New Microsoft.VisualBasic.Compatibility.VB6.RadioButtonArray(Me.components)
CType(Me.optRes, System.ComponentModel.ISupportInitialize).BeginInit()
CType(Me.optShut, System.ComponentModel.ISupportInitialize).BeginInit()
Me.SuspendLayout()
'
'_optRes_2
'
Me._optRes_2.BackColor = System.Drawing.SystemColors.Control
Me._optRes_2.Cursor = System.Windows.Forms.Cursors.Default
Me._optRes_2.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me._optRes_2.ForeColor = System.Drawing.SystemColors.ControlText
Me.optRes.SetIndex(Me._optRes_2, CType(2, Short))
Me._optRes_2.Location = New System.Drawing.Point(53, 64)
Me._optRes_2.Name = "_optRes_2"
Me._optRes_2.RightToLeft = System.Windows.Forms.RightToLeft.No
Me._optRes_2.Size = New System.Drawing.Size(81, 13)
Me._optRes_2.TabIndex = 4
Me._optRes_2.TabStop = True
Me._optRes_2.Text = "1024 x 768"
'
'_optRes_1
'
Me._optRes_1.BackColor = System.Drawing.SystemColors.Control
Me._optRes_1.Cursor = System.Windows.Forms.Cursors.Default
Me._optRes_1.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me._optRes_1.ForeColor = System.Drawing.SystemColors.ControlText
Me.optRes.SetIndex(Me._optRes_1, CType(1, Short))
Me._optRes_1.Location = New System.Drawing.Point(53, 40)
Me._optRes_1.Name = "_optRes_1"
Me._optRes_1.RightToLeft = System.Windows.Forms.RightToLeft.No
Me._optRes_1.Size = New System.Drawing.Size(89, 13)
Me._optRes_1.TabIndex = 3
Me._optRes_1.TabStop = True
Me._optRes_1.Text = "800 x 600"
'
'_optRes_0
'
Me._optRes_0.BackColor = System.Drawing.SystemColors.Control
Me._optRes_0.Cursor = System.Windows.Forms.Cursors.Default
Me._optRes_0.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me._optRes_0.ForeColor = System.Drawing.SystemColors.ControlText
Me.optRes.SetIndex(Me._optRes_0, CType(0, Short))
Me._optRes_0.Location = New System.Drawing.Point(53, 16)
Me._optRes_0.Name = "_optRes_0"
Me._optRes_0.RightToLeft = System.Windows.Forms.RightToLeft.No
Me._optRes_0.Size = New System.Drawing.Size(81, 13)
Me._optRes_0.TabIndex = 2
Me._optRes_0.TabStop = True
Me._optRes_0.Text = "640 x 480"
'
'cmdChange
'
Me.cmdChange.BackColor = System.Drawing.SystemColors.Control
Me.cmdChange.Cursor = System.Windows.Forms.Cursors.Default
Me.cmdChange.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me.cmdChange.ForeColor = System.Drawing.SystemColors.ControlText
Me.cmdChange.Location = New System.Drawing.Point(53, 87)
Me.cmdChange.Name = "cmdChange"
Me.cmdChange.RightToLeft = System.Windows.Forms.RightToLeft.No
Me.cmdChange.Size = New System.Drawing.Size(113, 25)
Me.cmdChange.TabIndex = 0
Me.cmdChange.Text = "&Change Resolution"
'
'Form1
'
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.BackColor = System.Drawing.SystemColors.Control
Me.ClientSize = New System.Drawing.Size(241, 125)
Me.Controls.Add(Me._optRes_2)
Me.Controls.Add(Me._optRes_1)
Me.Controls.Add(Me._optRes_0)
Me.Controls.Add(Me.cmdChange)
Me.Cursor = System.Windows.Forms.Cursors.Default
Me.Font = New System.Drawing.Font("Arial", 8.0!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle
Me.Location = New System.Drawing.Point(355, 151)
Me.MaximizeBox = False
Me.MinimizeBox = False
Me.Name = "Form1"
Me.RightToLeft = System.Windows.Forms.RightToLeft.No
Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen
Me.Text = "Change the Screen Resolution"
CType(Me.optRes, System.ComponentModel.ISupportInitialize).EndInit()
CType(Me.optShut, System.ComponentModel.ISupportInitialize).EndInit()
Me.ResumeLayout(False)
End Sub
#End Region
Private Sub cmdChange_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdChange.Click
Dim x As DEVMODE
Dim y As Integer
Dim z As Short

y = EnumDisplaySettings(0, 0, x)
With x
.dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT
If optRes(0).Checked Then
.dmPelsWidth = 640
.dmPelsHeight = 480
ElseIf optRes(1).Checked Then
.dmPelsWidth = 800
.dmPelsHeight = 600
Else
.dmPelsWidth = 1024
.dmPelsHeight = 768
End If

End With

y = ChangeDisplaySettings(x, CDS_TEST)

Select Case y
Case DISP_CHANGE_RESTART
z = MsgBox("You must restart your computer to apply these changes." & vbCrLf & vbCrLf & "Do you want to restart now?", MsgBoxStyle.YesNo + MsgBoxStyle.SystemModal, "Screen Resolution")
If z = MsgBoxResult.Yes Then Call ExitWindowsEx(EWX_REBOOT, 0)
Case DISP_CHANGE_SUCCESSFUL
Call ChangeDisplaySettings(x, CDS_UPDATEREGISTRY)
MsgBox("Screen resolution changed", MsgBoxStyle.Information, "Resolution Changed")
Case Else
MsgBox("Mode not supported", MsgBoxStyle.SystemModal, "Error")
End Select
End Sub
End Class

Bob Learned

I took the code, and made it a little more modular, and tested it against some different resolutions and I don't see the problem with the taskbar (Windows 2000 SP4):

Public Class Screen

Public Structure DeviceMode

Private Const CCDEVICENAME As Short = 32
Private Const CCFORMNAME As Short = 32

<VBFixedString(CCDEVICENAME), System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst:=CCDEVICENAME)> Public dmDeviceName As String
Dim dmSpecVersion As Short
Dim dmDriverVersion As Short
Dim dmSize As Short
Dim dmDriverExtra As Short
Dim dmFields As Integer
Dim dmOrientation As Short
Dim dmPaperSize As Short
Dim dmPaperLength As Short
Dim dmPaperWidth As Short
Dim dmScale As Short
Dim dmCopies As Short
Dim dmDefaultSource As Short
Dim dmPrintQuality As Short
Dim dmColor As Short
Dim dmDuplex As Short
Dim dmYResolution As Short
Dim dmTTOption As Short
Dim dmCollate As Short
<VBFixedString(CCFORMNAME), System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst:=CCFORMNAME)> Public dmFormName As String
Dim dmUnusedPadding As Short
Dim dmBitsPerPel As Short
Dim dmPelsWidth As Integer
Dim dmPelsHeight As Integer
Dim dmDisplayFlags As Integer
Dim dmDisplayFrequency As Integer
End Structure 'DeviceMode'

Private Declare Function EnumDisplaySettings _
Lib "user32" Alias "EnumDisplaySettingsA" _
(ByVal lpszDeviceName As Integer, ByVal iModeNum As Integer, _
ByRef lpDevMode As DeviceMode) As Boolean

Private Declare Function ChangeDisplaySettings _
Lib "user32" Alias "ChangeDisplaySettingsA" _
(ByRef lpDevMode As DeviceMode, ByVal dwFlags As Integer) _
As Integer

Private Declare Function ExitWindowsEx Lib "user32" _
(ByVal uFlags As Integer, ByVal dwReserved As Integer) As Integer

Public Shared Function ChangeResolution( _
ByVal resWidth As Integer, ByVal resHeight As Integer) As Boolean

Const CDS_TEST As Short = &H4
Const CDS_UPDATEREGISTRY As Short = &H1
Const DISP_CHANGE_SUCCESSFUL As Short = 0
Const DISP_CHANGE_RESTART As Short = 1
Const EWX_REBOOT As Short = 2

' Get all the available device modes.
Dim deviceList As DeviceMode() = _
EnumerateScreenModes()

' Assume the resolution settings are valid.
Dim validResolution As Boolean = True

' Pick the corresponding resolution with the
' highest frequency.
Dim selectedDevice As DeviceMode = _
SelectResolution(deviceList, resWidth, resHeight)

' If there isn't a matching resolution for the
' desired width x height, then throw an
' exception.
If selectedDevice.Equals(New DeviceMode) Then
Throw New ArgumentException("Unsupported screen resolution: " & _
resWidth & " x " & resHeight)
End If

Dim restartMode As Integer = _
ChangeDisplaySettings(selectedDevice, CDS_TEST)

Select Case restartMode

Case DISP_CHANGE_RESTART

' Ask to restart.
Dim resultRestart As MsgBoxResult = _
MsgBox("You must restart your computer to apply these changes." & vbCrLf & vbCrLf & "Do you want to restart now?", MsgBoxStyle.YesNo + MsgBoxStyle.SystemModal, "Screen Resolution")

If resultRestart = MsgBoxResult.Yes Then
' Reboot the machine.
ExitWindowsEx(EWX_REBOOT, 0)
End If

Case DISP_CHANGE_SUCCESSFUL

' Automatically change the resolution.
Call ChangeDisplaySettings(selectedDevice, CDS_UPDATEREGISTRY)

Case Else
Throw New Exception("Mode not supported")

End Select 'restartMode'

End Function 'ChangeResolution'

Public Shared Function EnumerateScreenModes() As DeviceMode()

Const DM_DISPLAYFREQUENCY As Integer = &H400000
Const DM_PELSWIDTH As Integer = &H80000
Const DM_PELSHEIGHT As Integer = &H100000

Dim deviceList As DeviceMode()
Dim errorResult As Integer
Dim countDevice As Integer = 0

Do

' Call the enumerate function until no more
' settings are found.
Dim deviceTest As DeviceMode

errorResult = EnumDisplaySettings(0, countDevice, deviceTest)

If errorResult <> 0 Then

ReDim Preserve deviceList(countDevice)

deviceList(countDevice) = deviceTest

' Set up the device to change the resolution
' and frequency.
deviceList(countDevice).dmFields = DM_PELSWIDTH Or _
DM_PELSHEIGHT Or DM_DISPLAYFREQUENCY

' Increment the counter.
countDevice += 1
End If

Loop Until errorResult = 0

Return deviceList

End Function 'EnumerateScreenModes'

Private Shared Function SelectResolution( _
ByVal deviceList As DeviceMode(), ByVal resWidth As Integer, _
ByVal resHeight As Integer) As DeviceMode

' Find the highest frequency for the
' desired screen dimensions.

Dim maxFrequency As Integer = 0
Dim selectDevice As DeviceMode = New DeviceMode

' Loop through each screen mode, and find the
' highest frequency.

For Each currentDevice As DeviceMode In deviceList

' Only test modes where the screen dimensions
' match.

If currentDevice.dmPelsWidth = resWidth And _
currentDevice.dmPelsHeight = resHeight Then

' Test the current device mode to see if the
' frequency is the maximum.

If currentDevice.dmDisplayFrequency > maxFrequency Then
maxFrequency = currentDevice.dmDisplayFrequency

selectDevice = currentDevice
End If

End If

Next currentDevice

Return selectDevice

End Function 'SelectResolution'

End Class 'Screen'

Bob

graye

Here is yet another version of the same thing...

Private Const CCDEVICENAME = 32
Private Const CCFORMNAME = 32
Private Const DM_PELSWIDTH = &H80000
Private Const DM_PELSHEIGHT = &H100000

'typedef struct _devicemode {
' BCHAR dmDeviceName[CCHDEVICENAME];
' WORD dmSpecVersion;
' WORD dmDriverVersion;
' WORD dmSize;
' WORD dmDriverExtra;
' DWORD dmFields;
' union {
' struct {
' short dmOrientation;
' short dmPaperSize;
' short dmPaperLength;
' short dmPaperWidth;
' short dmScale;
' short dmCopies;
' short dmDefaultSource;
' short dmPrintQuality;
' };
' POINTL dmPosition;
' DWORD dmDisplayOrientation;
' DWORD dmDisplayFixedOutput;
' };
' short dmColor;
' short dmDuplex;
' short dmYResolution;
' short dmTTOption;
' short dmCollate;
' BYTE dmFormName[CCHFORMNAME];
' WORD dmLogPixels;
' DWORD dmBitsPerPel;
' DWORD dmPelsWidth;
' DWORD dmPelsHeight;
' union {
' DWORD dmDisplayFlags;
' DWORD dmNup;
' }
' DWORD dmDisplayFrequency;
'#if(WINVER >= 0x0400)
' DWORD dmICMMethod;
' DWORD dmICMIntent;
' DWORD dmMediaType;
' DWORD dmDitherType;
' DWORD dmReserved1;
' DWORD dmReserved2;
'#if (WINVER >= 0x0500) || (_WIN32_WINNT >= 0x0400)
' DWORD dmPanningWidth;
' DWORD dmPanningHeight;
'#End If
'#endif /* WINVER >= 0x0400 */
'} DEVMODE;

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi, Pack:=4)> _
Private Structure DEVMODE
<MarshalAs(UnmanagedType.ByValTStr, sizeconst:=CCDEVICENAME)> Dim dmDeviceName As String
Dim dmSpecVersion As Short
Dim dmDriverVersion As Short
Dim dmSize As Short
Dim dmDriverExtra As Short
Dim dmFields As Integer
Dim dmOrientation As Short
Dim dmPaperSize As Short
Dim dmPaperLength As Short
Dim dmPaperWidth As Short
Dim dmScale As Short
Dim dmCopies As Short
Dim dmDefaultSource As Short
Dim dmPrintQuality As Short
Dim dmColor As Short
Dim dmDuplex As Short
Dim dmYResolution As Short
Dim dmTTOption As Short
Dim dmCollate As Short
<MarshalAs(UnmanagedType.ByValTStr, sizeconst:=CCFORMNAME)> Dim dmFormName As String
Dim dmUnusedPadding As Short
Dim dmBitsPerPel As Short
Dim dmPelsWidth As Integer
Dim dmPelsHeight As Integer
Dim dmDisplayFlags As Integer
Dim dmDisplayFrequency As Integer
End Structure

'BOOL EnumDisplaySettings(
' LPCTSTR lpszDeviceName, // display device
' DWORD iModeNum, // graphics mode
' LPDEVMODE lpDevMode // graphics mode settings
');
Private Declare Ansi Function EnumDisplaySettings Lib "user32" _
Alias "EnumDisplaySettingsA" _
(ByVal lpszDeviceName As Integer, _
ByVal iModeNum As Integer, _
ByRef lpDevMode As DEVMODE) As Boolean

'LONG ChangeDisplaySettings(
' LPDEVMODE lpDevMode, // graphics mode
' DWORD dwflags // graphics mode options
');
Private Declare Ansi Function ChangeDisplaySettings Lib "user32" _
Alias "ChangeDisplaySettingsA" _
(ByRef lpDevMode As DEVMODE, _
ByVal dwflags As Integer) As Integer

Private Sub ChangeRes(ByVal iWidth As Integer, ByVal iHeight As Integer, Optional ByVal iColorDepth As Integer = 0)
Dim blnWorked As Boolean
Dim i As Integer
Dim DevM As DEVMODE

i = 0
Do
blnWorked = EnumDisplaySettings(0, i, DevM)
If blnWorked Then
If DevM.dmPelsWidth = iWidth And DevM.dmPelsHeight = iHeight Then
Debug.WriteLine(DevM.dmBitsPerPel)
If iColorDepth > 0 Then
DevM.dmBitsPerPel = iColorDepth
End If
ChangeDisplaySettings(DevM, 0)
Exit Sub
End If
End If
i = i + 1
Loop Until (blnWorked = False)
End Sub

bkniazi

ASKER

Hi TheLearnedOne
Sorry for giving a late comment,I have checked your class code it working nice for changing resolution from 800x600
to 1024x768, but when we change resolution from 1024x768 to 800x600 then the task bar hides from the screen
Same problem occur in changing to 640x480.I have also windows 2000 and Sp4 like you.
Please check it ,Thanks

bkniazi

ASKER

Hi graye,
Thanks for replying to my question I have used your example Module but the taskbar hides when we change
the resolution to 800x600.Please work on this problem area.Many thanks.................................................

Bob Learned

In my code, this is the line that causes problems:

ChangeDisplaySettings(selectedDevice, CDS_TEST)

If you comment this line out, then it works fine changing from 1024 x 768 to 800 x 600. I don't know why this messes things up.

Bob

ASKER CERTIFIED SOLUTION

Bob Learned

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bkniazi

ASKER

Hi TheLearnedOne,
Many thanks for solving the problem in my code.You have answered in a best way
A lot of thanks again..................