VB Snippet - Changing Resolution

[James Stanich]

Option Explicit
 
Private Const CCDEVICENAME = 32
Private Const CCFORMNAME = 32
 
Private Const DISP_CHANGE_SUCCESSFUL = 0
Private Const DISP_CHANGE_RESTART = 1
Private Const DISP_CHANGE_FAILED = -1
Private Const DISP_CHANGE_BADMODE = -2
Private Const DISP_CHANGE_NOTUPDATED = -3
Private Const DISP_CHANGE_BADFLAGS = -4
Private Const DISP_CHANGE_BADPARAM = -5
 
Private Const CDS_UPDATEREGISTRY = &H1
Private Const CDS_TEST = &H2
 
Private Const DM_BITSPERPEL = &H40000
Private Const DM_PELSWIDTH = &H80000
Private Const DM_PELSHEIGHT = &H100000
 
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
 
Private Declare Function EnumDisplaySettings Lib "user32" Alias "EnumDisplaySettingsA" (ByVal lpszDeviceName As Long, ByVal iModeNum As Long, lpDevMode As Any) As Boolean
Private Declare Function ChangeDisplaySettings Lib "user32" Alias "ChangeDisplaySettingsA" (lpDevMode As Any, ByVal dwflags As Long) As Long
 
Function ChangeScreenSettings(lWidth As Integer, lHeight As Integer, lColors As Integer)
Dim tDevMode As DEVMODE, lTemp As Long, lIndex As Long
lIndex = 0
Do
lTemp = EnumDisplaySettings(0&, lIndex, tDevMode)
If lTemp = 0 Then Exit Do
lIndex = lIndex + 1
 
With tDevMode
If .dmPelsWidth = lWidth And .dmPelsHeight = lHeight And .dmBitsPerPel = lColors Then
lTemp = ChangeDisplaySettings(tDevMode, CDS_UPDATEREGISTRY)
Exit Do
End If
End With
Loop
End Function
 
' Then Call
 
ChangeScreenSettings 800, 600, 16
 
' x, y, color depth in bits