Cambiar la resolucion de la pantalla al entrar en un programa.

Laura
06 de Octubre del 2003
Bueno he visto algun ejemplo por ahi, pero no me funciona, yo concretamente, tengo una aplicacion hecha en Access, y quisiera que cuando se abra, te cambia la resolucion de tu pantalla a 1024x768, para que todos los formularios se vean bien.
Gracias

sdemingo
06 de Octubre del 2003
Hola Laura,
no se puede cambiar la resolución de todos los monitores a 1024x768 pixels. Hay monitores que no lo aceptan, y ya está, pero hay otros que petarían. Te recomiendo que busques otra alternativa.

Un saludo
sdemingo

Laura
06 de Octubre del 2003
Ya te entiendo, pero mi caso no es ese, realmente, todos los ordenadores que llevan esa aplicacion, estan en la empresa donde trabajo y si que admiten esa resolucion, el problema, es que hay un par de pencos, que no ven dos arriba de un burro y necesitan poner la resolucion de su pantalla a 800x600 y cuando abren la aplicacion les salen formularios con botones escondidos, y por esos dos cazurdos, no voy a cambiar todo la aplicacion que tiene 70 formularios.. Entiendes?, por eso quiero cambiarles la resolucion solo cuando entren en el programa.
Gracias

sdemingo
06 de Octubre del 2003
Ok, pues prueba esta código en una aplicación VB6.
Lo que hace es que en el Load del formulario guarda la configuración actual de la pantalla y la cambia a 800x600. Luego, al finalizar la aplicación. en el evento Form_Unload, reestablece la pantalla a sus dimensiones originales.
Pruébalo y modificalo a tu gusto.
Las variables, constantes y Funciones que declara son para acceder a la API.

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()
'KPD-Team 1999
'URL: http://www.allapi.net/
'E-Mail: [email protected]
Dim nDC As Long
'retrieve the screen's resolution
OldX = Screen.Width / Screen.TwipsPerPixelX
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 800, 600, 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

Un saludo
sdemingo