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Get an RGB Colour from an OLE_COLOR

Author:

Steve McMahon(steve@vbaccelerator.com)

Keywords:

API,GDI,Graphics,Windows Controls

Updated:

09/08/98

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Sometimes you need to know the Red, Green and Blue values of a Visual Basic OLE Colour, particularly if you are going to use the colour in an API function. This tip shows you how to correctly convert an OLE_COLOR type to a RGB value using the OleTranslateColor API call exposed by OLEPRO32.DLL. It works for all colours, whether they are RGB colours, system colours of the type &H80000000F (vbButtonFace) or palette-matching colours such as &H2EECC99.

Start a new project in VB. Add the following code to the project's form:

Private Declare Function OleTranslateColor Lib "OLEPRO32.DLL" (ByVal OLE_COLOR As Long, ByVal HPALETTE As Long, pccolorref As Long) As Long
Private Const CLR_INVALID = -1

Private Function TranslateColor(ByVal oClr As OLE_COLOR, _
&nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp Optional hPal As Long = 0) As Long
&nbsp &nbsp
' Convert Automation color to Windows color
&nbsp &nbsp If OleTranslateColor(oClr, hPal, TranslateColor) Then
&nbsp &nbsp &nbsp &nbsp TranslateColor = CLR_INVALID
&nbsp &nbsp End If
End Function

To test out the function, add a Combo box, a Label and a Text Box to the project's form. Set the style of the Combo box to 2 (Drop Down List) and then add the following code:

Private Sub Combo1_Click()
Dim lRGB As Long
&nbsp &nbsp
&nbsp &nbsp Label1.BackColor = Combo1.ItemData(Combo1.ListIndex)
&nbsp &nbsp lRGB = TranslateColor(Combo1.ItemData(Combo1.ListIndex))
&nbsp &nbsp Text1.Text = "R=" & (lRGB And &HFF&) & ",G=" & (lRGB And &HFF00&) \ &H100 & ",B=" & (lRGB And &HFF0000) \ &H10000

End Sub

Private Sub Form_Load()
Dim i As Long
Dim sNum As String
&nbsp &nbsp For i = 1 To &H18&
&nbsp &nbsp &nbsp &nbsp sNum = Hex$(i)
&nbsp &nbsp &nbsp &nbsp If Len(sNum) = 1 Then sNum = "0" & sNum
&nbsp &nbsp &nbsp &nbsp Combo1.AddItem "&H800000" & sNum
&nbsp &nbsp &nbsp &nbsp Combo1.ItemData(Combo1.NewIndex) = &H80000000 + i
&nbsp &nbsp Next i
&nbsp &nbsp Combo1.ListIndex = 0
End Sub

When you change the selected item in the combo box , the text box will be set to the R,G,B components of the colour.


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Copyright 1998-1999, Steve McMahon ( steve@vbaccelerator.com). All Rights Reserved.
Last updated: 09/08/98