I can use following codes to change resolution but problem is that when I run my program it changes resolution(1280*1024) & show form which doesnt fit the screen though its width is 1280 & height is 1024. But when I close that program & run it again then it works I mean fit with the screen. It means first time when I run my program it changes resolution but cant fit form with screen. So can you tell me how should I do three things together like when I run my program it changes resolution & fit my form with screen & when I close it it will get back its previous resolution. Please help me.

Code :

Imports System.Runtime.InteropServices
Public Module resChanger
Const CDS_TEST As Long = &H2
Const CCDEVICENAME As Integer = 32
Const CCFORMNAME As Integer = 32
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)
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)
lResult = ChangeDisplaySettings(DevM, CDS_UPDATEREGISTRY)
End If
End Sub
End Module

Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Call changeRes(1280, 1024)
End Sub
End Class

Try this:
After Call ChangeRes(1280, 1024) , add the line Me.WindowState = FormWindowState.Maximized .

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