_ChangeScreenRes UDF issue

[psychopyro212]

Im Currently using this udf:

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;===============================================================================
;
; Function Name: _ChangeScreenRes()
; Description: Changes the current screen geometry, colour and refresh rate.
; Version: 1.0.0.1
; Parameter(s): $i_Width - Width of the desktop screen in pixels. (horizontal resolution)
; $i_Height - Height of the desktop screen in pixels. (vertical resolution)
; $i_BitsPP - Depth of the desktop screen in bits per pixel.
; $i_RefreshRate - Refresh rate of the desktop screen in hertz.
; Requirement(s): AutoIt Beta > 3.1
; Return Value(s): On Success - Screen is adjusted, @ERROR = 0
; On Failure - sets @ERROR = 1
; Forum(s): http://www.autoitscript.com/forum/index.php?showtopic=20121
; Author(s): Original code - psandu.ro
; Modifications - PartyPooper
;
;===============================================================================

Func _ChangeScreenRes($i_Width = @DesktopWidth, $i_Height = @DesktopHeight, $i_BitsPP = @DesktopDepth, $i_RefreshRate = @DesktopRefresh)
Local Const $DM_PELSWIDTH = 0x00080000
Local Const $DM_PELSHEIGHT = 0x00100000
Local Const $DM_BITSPERPEL = 0x00040000
Local Const $DM_DISPLAYFREQUENCY = 0x00400000
Local Const $CDS_TEST = 0x00000002
Local Const $CDS_UPDATEREGISTRY = 0x00000001
Local Const $DISP_CHANGE_RESTART = 1
Local Const $DISP_CHANGE_SUCCESSFUL = 0
Local Const $HWND_BROADCAST = 0xffff
Local Const $WM_DISPLAYCHANGE = 0x007E
If $i_Width = "" Or $i_Width = -1 Then $i_Width = @DesktopWidth ; default to current setting
If $i_Height = "" Or $i_Height = -1 Then $i_Height = @DesktopHeight ; default to current setting
If $i_BitsPP = "" Or $i_BitsPP = -1 Then $i_BitsPP = @DesktopDepth ; default to current setting
If $i_RefreshRate = "" Or $i_RefreshRate = -1 Then $i_RefreshRate = @DesktopRefresh ; default to current setting
Local $DEVMODE = DllStructCreate("byte[32];int[10];byte[32];int[6]")
Local $B = DllCall("user32.dll", "int", "EnumDisplaySettings", "ptr", 0, "long", 0, "ptr", DllStructGetPtr($DEVMODE))
If @error Then
$B = 0
SetError(1)
Return $B
Else
$B = $B[0]
EndIf
If $B <> 0 Then
DllStructSetData($DEVMODE, 2, BitOR($DM_PELSWIDTH, $DM_PELSHEIGHT, $DM_BITSPERPEL, $DM_DISPLAYFREQUENCY), 5)
DllStructSetData($DEVMODE, 4, $i_Width, 2)
DllStructSetData($DEVMODE, 4, $i_Height, 3)
DllStructSetData($DEVMODE, 4, $i_BitsPP, 1)
DllStructSetData($DEVMODE, 4, $i_RefreshRate, 5)
$B = DllCall("user32.dll", "int", "ChangeDisplaySettings", "ptr", DllStructGetPtr($DEVMODE), "int", $CDS_TEST)
If @error Then
$B = -1
Else
$B = $B[0]
EndIf
Select
Case $B = $DISP_CHANGE_RESTART
$DEVMODE = ""
Return 2
Case $B = $DISP_CHANGE_SUCCESSFUL
DllCall("user32.dll", "int", "ChangeDisplaySettings", "ptr", DllStructGetPtr($DEVMODE), "int", $CDS_UPDATEREGISTRY)
DllCall("user32.dll", "int", "SendMessage", "hwnd", $HWND_BROADCAST, "int", $WM_DISPLAYCHANGE, _
"int", $i_BitsPP, "int", $i_Height * 2 ^ 16 + $i_Width)
$DEVMODE = ""
Return 1
Case Else
$DEVMODE = ""
SetError(1)
Return $B
EndSelect
EndIf
EndFunc ;==>_ChangeScreenRes

This works great when changing my resolution to 1024 X 768 but it will not change my resolution to 1366 x 768 anyone care to take a stab at this? Im using windows 7 home premium X64

[psychopyro212]

Bump I simply dont understand why this does not work... all its doing is changing the width.... it has no problem setting to 1024x768

[JohnOne]

Perhaps your display device does not support that resolution.

[TechEngr]

I am using the same function on WinXP..  setting displays of greater than 1024x768.  But having problem setting display on Win7.  And since I am not familiar with codes used (DllStructCreate, DllStructSetData and DllCall), I tried modifying the first $devmode preset to:

Local $DEVMODE = DllStructCreate("byte[32];int64[10];byte[32];int[6]") 

the output changed, but not the output I wanted.

Could anyone shed a light on how to manipulate the codes or why it was used?