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Problem with screen resolutation

Posted on 2014-07-28
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Last Modified: 2014-07-29
I have a program that runs best at 1280 x 800 resolutation.
The plan
prompt the user on load if running a different resolutation.
Change resolutation ?
Always change resolutationon program start ?
Change back when app closes ?
Always Change back when app closes ?
The problem I have run into is the changing back on program close is reported improper.
I am running 1280 x 800, but it is reporting 800 x 800
What is wrong with this code to report improper 800 x 800 ?


 OldX = Screen.Width / Screen.TwipsPerPixelX this says 800 should be 1280


Option Explicit
Const WM_DISPLAYCHANGE = &H7E
Const HWND_BROADCAST = &HFFFF&
Const EWX_LOGOFF = 0
Const EWX_SHUTDOWN = 1
Const EWX_REBOOT = 2
Const EWX_FORCE = 4
Const CCDEVICENAME = 32
Const CCFORMNAME = 32
Const DM_BITSPERPEL = &H40000
Const DM_PELSWIDTH = &H80000
Const DM_PELSHEIGHT = &H100000
Const CDS_UPDATEREGISTRY = &H1
Const CDS_TEST = &H4
Const DISP_CHANGE_SUCCESSFUL = 0
Const DISP_CHANGE_RESTART = 1
Const BITSPIXEL = 12
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
Private Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Long, ByVal dwReserved As Long) As Long
Private Declare Function GetDeviceCaps Lib "gdi32" (ByVal hdc As Long, ByVal nIndex As Long) As Long
Private Declare Function CreateDC Lib "gdi32" Alias "CreateDCA" (ByVal lpDriverName As String, ByVal lpDeviceName As String, ByVal lpOutput As String, ByVal lpInitData As Any) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Dim OldX As Long, OldY As Long, nDC As Long
Sub ChangeRes(X As Long, Y As Long, Bits As Long)
    Dim DevM As DEVMODE, ScInfo As Long, erg As Long, an As VbMsgBoxResult
    'Get the info into DevM
    erg = EnumDisplaySettings(0&, 0&, DevM)
    'This is what we're going to change
    DevM.dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT Or DM_BITSPERPEL
    DevM.dmPelsWidth = X 'ScreenWidth
    DevM.dmPelsHeight = Y 'ScreenHeight
    DevM.dmBitsPerPel = Bits '(can be 8, 16, 24, 32 or even 4)
    'Now change the display and check if possible
    erg = ChangeDisplaySettings(DevM, CDS_TEST)
    'Check if succesfull
    Select Case erg&
        Case DISP_CHANGE_RESTART
            an = MsgBox("You've to reboot", vbYesNo + vbSystemModal, "Info")
            If an = vbYes Then
                erg& = ExitWindowsEx(EWX_REBOOT, 0&)
            End If
        Case DISP_CHANGE_SUCCESSFUL
            erg = ChangeDisplaySettings(DevM, CDS_UPDATEREGISTRY)
            ScInfo = Y * 2 ^ 16 + X
            'Notify all the windows of the screen resolution change
            SendMessage HWND_BROADCAST, WM_DISPLAYCHANGE, ByVal Bits, ByVal ScInfo
            MsgBox "Everything's ok", vbOKOnly + vbSystemModal, "It worked!"
        Case Else
            MsgBox "Mode not supported", vbOKOnly + vbSystemModal, "Error"
    End Select
End Sub
Private Sub Form_Load()
     Dim nDC As Long
    'retrieve the screen's resolution
    OldX = Screen.Width / Screen.TwipsPerPixelX 'this wrong
    OldY = Screen.Height / Screen.TwipsPerPixelY
    'Create a device context, compatible with the screen
    nDC = CreateDC("DISPLAY", vbNullString, vbNullString, ByVal 0&)
    'Change the screen's resolution
    ChangeRes 1280, 800, GetDeviceCaps(nDC, BITSPIXEL)
End Sub
Private Sub Form_Unload(Cancel As Integer)
    'restore the screen resolution
    ChangeRes OldX, OldY, GetDeviceCaps(nDC, BITSPIXEL)
    'delete our device context
    DeleteDC nDC
End Sub

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Question by:isnoend2001
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Expert Comment

by:5teveo
ID: 40225813
Try remembering screens resolution prior to change using

        vScreenW = Screen.PrimaryScreen.WorkingArea.Width
        vScreenH = Screen.PrimaryScreen.WorkingArea.Height

'change screen resolution...

restore resolution using vScreen? vlaues

Then use prior value upon restore...
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Author Comment

by:isnoend2001
ID: 40225833
Thanks, but
.PrimaryScreen vb says method or data member not found
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LVL 8

Expert Comment

by:5teveo
ID: 40225939
Do don't have access to Screen.PrimaryScreen.WorkingArea.??? controls?

I thought it was embedded in vB... I do need imports to expose
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Expert Comment

by:eemit
ID: 40226262
Never change user Screen Resolution!
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Author Comment

by:isnoend2001
ID: 40226657
are you talking vb6
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Accepted Solution

by:
eemit earned 500 total points
ID: 40227262
Your program must be adapted to the user's monitor resolution, and not vice versa.

For error that you get:
Use GetDeviceCaps API

Private Declare Function GetDeviceCaps Lib "gdi32" (ByVal hdc As Long, ByVal nIndex As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long

Private Const HORZRES = 8
Private Const VERTRES = 10

Private Sub Form_Load()
    Dim hdc as Long

    hdc = GetDC(0)
    OldX = GetDeviceCaps(hdc, HORZRES)
    OldY = GetDeviceCaps(hdc, VERTRES)
End Sub

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Author Closing Comment

by:isnoend2001
ID: 40227411
Thanks that works
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