Determine the Colour Depth

This piece of code shows you how to find out the colour depth of the screen using the GetDeviceCaps API.

Private Declare Function GetDeviceCaps Lib "GDI32" (ByVal hDC As Long, ByVal nIndex As Long) As Long

Function DeviceColors(hDC As Long) As Single
    Const PLANES = 14
    Const BITSPIXEL = 12
    DeviceColors = 2 ^ (GetDeviceCaps(hDC, PLANES) * GetDeviceCaps(hDC, BITSPIXEL))
End Function

Private Sub cmdGetColours_click()
    Dim fColours As Single
    fColours = DeviceColors((hDC))
    If fColours = "4.294967E+09" Then
        lblColours.Caption = "Colors: " & Colours & " -True Color (32 bit)"
    ElseIf fColours = "65536" Then
        lblColours.Caption = "Colors: " & Colours & " - High Color (16 bit)"
    Else
        lblColours.Caption = "Colors: " & Colours
    End If
End Sub