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Language: VB4/32,VB5,VB6
Expertise: Intermediate
Jan 20, 2001



Building the Right Environment to Support AI, Machine Learning and Deep Learning

GetDisplaySettings - Retrieve information about available display modes

Const DM_BITSPERPEL As Long = &H40000
Const DM_PELSWIDTH As Long = &H80000
Const DM_PELSHEIGHT As Long = &H100000

Const CCDEVICENAME As Long = 32
Const CCFORMNAME As Long = 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 Long
    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 modeIndex As Long, lpDevMode As Any) As Boolean

' Fill two arrays with information about all available display modes
' displayInfo() is a bi-dimentional matrix where each row is a display mode
'     displayInfo(n, 0) is the horizontal resolution
'     displayInfo(n, 1) is the vertical resolution
'     displayInfo(n, 2) is the number of colors
'     displayInfo(n, 0) is refresh rate (in MHz) or zero if not available
' displayDescr() is an array of string that contains the same information
'     but in a textual format, ready to be displayed in a menu or listbox

Sub GetDisplaySettings(displayInfo() As Long, displayDescr() As String)
    Dim lpDevMode As DEVMODE
    Dim index As Long
    Dim displayCount As Long
    Dim colorDescr As String
    ' set the DEVMODE flags and structure size
    lpDevMode.dmSize = Len(lpDevMode)
    ' count how many display settings are there
    Do While EnumDisplaySettings(0, displayCount, lpDevMode) > 0
        displayCount = displayCount + 1
    ' now displayCount holds the number of display settings
    ' and we can DIMension the result arrays
    ReDim displayInfo(0 To displayCount - 1, 0 To 3) As Long
    ReDim displayDescr(0 To displayCount - 1) As String
    For index = 0 To displayCount - 1
        ' retrieve info on the Nth display mode
        EnumDisplaySettings 0, index, lpDevMode
        ' fill the displayInfo structure
        displayInfo(index, 0) = lpDevMode.dmPelsWidth
        displayInfo(index, 1) = lpDevMode.dmPelsHeight
        displayInfo(index, 2) = 2 ^ IIf(lpDevMode.dmBitsPerPel > 24, 24, _
        If lpDevMode.dmDisplayFrequency > 1 Then
            displayInfo(index, 0) = lpDevMode.dmDisplayFrequency
        End If
        ' prepare a description for this display mode
        Select Case displayInfo(index, 2)
            Case 16
                colorDescr = "16 colors"
            Case 256
                colorDescr = "256 colors"
            Case Is <= 65536
                colorDescr = "High color"
            Case Else
                colorDescr = "True color"
        End Select
        displayDescr(index) = lpDevMode.dmPelsWidth & " x " & _
            lpDevMode.dmPelsHeight & ", " & colorDescr
        If lpDevMode.dmDisplayFrequency > 1 Then
            displayDescr(index) = displayDescr(index) & ", " & _
                lpDevMode.dmDisplayFrequency & " MHz"
        End If

End Sub
Francesco Balena
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