Changing screen resolution in Excel by VBA?

[Sickbock]

I have a computer that can manually be switched to 2 monitors. Both monitors do not have the same screen resolution. I am running a macro controlled presentation in Excel 2010 and I want to change the screen resolution when switching to the other monitor. In a previous post, “Change Screen Resolution using VB”, I found the following solution:

'************************************************* ****************
' DECLARATIONS SECTION
'************************************************* ****************

Option Compare Database
Option Explicit

Type RECT
x1 As Long
y1 As Long
x2 As Long
y2 As Long
End Type

' NOTE: The following declare statements are case sensitive.

Declare Function GetDesktopWindow Lib "User32" () As Long
Declare Function GetWindowRect Lib "User32" _
(ByVal hWnd As Long, rectangle As RECT) As Long
'================================================= =====

'This code shows how to change the screen resolution.

'Call the function like this:

' ChangeResolution 640, 480

'This would change the screen resolution to 640 pixels x 480 pixels. Note
that
'you can only change the resolution to values supported by the display.

'Paste the following code into a module:'

Private Declare Function ChangeDisplaySettings Lib "User32" Alias _
"ChangeDisplaySettingsA" (lpDevMode As Any, ByVal dwFlags As Long) As Long
Private Declare Function EnumDisplaySettings Lib "User32" Alias _
"EnumDisplaySettingsA" (ByVal lpszDeviceName As Long, ByVal iModeNum As _
Long, lpDevMode As Any) As Boolean

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

Private 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

Public Function Change_Resolution(iWidth As Single, iHeight As Single)

Dim DevM As DEVMODE
Dim a As Boolean
Dim i As Long
Dim b As Long

i = 0

'Enumerate settings
Do
a = EnumDisplaySettings(0&, i&, DevM)
i = i + 1
Loop Until (a = False)

'Change settings
DevM.dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT

DevM.dmPelsWidth = iWidth
DevM.dmPelsHeight = iHeight

b = ChangeDisplaySettings(DevM, 0)

End Function

'************************************************* ****************
' FUNCTION: GetScreenResolution()
'
' PURPOSE:
' To determine the current screen size or resolution.
'
' RETURN:
' The current screen resolution. Typically one of the following:
' 640 x 480
' 800 x 600
' 1024 x 768
'
'************************************************* ****************
Function GetScreenResolution() As String

Dim R As RECT
Dim hWnd As Long
Dim RetVal As Long

hWnd = GetDesktopWindow()
RetVal = GetWindowRect(hWnd, R)
GetScreenResolution = (R.x2 - R.x1) & "x" & (R.y2 - R.y1)

End Function

I pasted the code to a module from a workbook but this does not function. Does anybody know what I am doing wrong an how to achieve my goal: Changing screen resolution in Excel by VBA?

[Rabbit]

You didn't call your function anywhere.

[Sickbock]

Thanks Rabbit for your quick response. This was a little bit stupid indeed. But now I am immediately facing the next problem. When I write a procedure to call the function to change the screen resolution, the automatic fill up function of VBA wants me to add a sign of equality behind the expression "change_resolut ion(1280, 1024)". But I do not know what to add behind the sign of equality. I now put a x behind it, and the screen resolution is changing by running this procedure. Nevertheless I get a failure message at the end:
"Failure 424 during running: Object necessary"
What do I need to change in the procedure as shown below to prevent the failure message?

Sub change()
change_resolution(1280, 1024) = x '????
End Sub

[Rabbit]

Subs are called without parentheses. Functions are called with parentheses.

[Sickbock]

Thanks Rabbit for your help
I have changed the code as shown below. This works

Sub change()
Call change_resolution(1280, 1024)
End Sub