Getting the display bitcount (i.e. 'colour depth')

[Robbie]

Hi again, does anybody know how to get the number of colours / colour depth which the display is set to use, in Visual Basic 6?
(i.e. 8-bit, 16-bit or 32-bit)

I know how to find out the horizontal/vertical resolution, but it's the depth I need...

[Killer42]

Hi again, does anybody know how to get the number of colours / colour depth which the display is set to use, in Visual Basic 6?
(i.e. 8-bit, 16-bit or 32-bit)

I know how to find out the horizontal/vertical resolution, but it's the depth I need...

Sourced from another forum...

Author: James Crowley

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 = 4294967296# Then
        Debug.Print "Colors: " & fColours & " - True Color (32 bit)"
    ElseIf fColours = 65536# Then
        Debug.Print "Colors: " & fColours & " - High Color (16 bit)"
    Else
        Debug.Print "Colors: " & fColours
    End If
End Sub

(Edited by Killer42. The original code contained bugs. I'll post it in another message, for historical interest.)

[Killer42]

Just in case anyone is interested, here is the original code, before I edited it.

Warning: This code contains at least one serious bug (in the test code, not the actual function)

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

[Robbie]

Sourced from another forum...

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

...

(Edited by Killer42. The original code contained bugs. I'll post it in another message, for historical interest.)

Thanks very much! ^^
Works just like it should.

[Killer42]

Thanks very much! ^^
Works just like it should.

Glad to hear it! :)

I might add this to the Articles area.