Convert system color to RGB

[Andrex]

How can I convert a color constant (such as vbWindowBackground) to RGB? The method I'm now using (see below) only works with colors retrieved from a CommonDialog color dialog selector.

RVal = Int(lSourceColor Mod 256)
GVal = Int((lSourceColor \ 256) Mod 256)
BVal = lSourceColor \ 65536

But this doesn't work with when lSourceColor is a system color constant. Do I have to convert the color to another format before using that RGB function? How?

[dglienna]

Take a look at this. I've included the source so that you don't have to make the form.

Option Explicit

Private Type HSL
	Hue As Long
	Saturation As Long
	Luminance As Long
End Type

Private Function HSLToRGB(ByVal Hue As Long, ByVal Saturation As Long, ByVal Luminance As Long) As Long
Dim R As Long, G As Long, B As Long
Dim lMax As Long, lMid As Long, lMin As Long
Dim Delta As Single
lMax = (Luminance * 255) / 100
lMin = (100 - Saturation) * lMax / 100
Delta = (lMax - lMin) / 60
Select Case Hue
Case 0 To 60
	lMid = (Hue - 0) * Delta + lMin
	R = lMax: G = lMid: B = lMin
Case 60 To 120
	lMid = -(Hue - 120) * Delta + lMin
	R = lMid: G = lMax: B = lMin
Case 120 To 180
	lMid = (Hue - 120) * Delta + lMin
	R = lMin: G = lMax: B = lMid
Case 180 To 240
	lMid = -(Hue - 240) * Delta + lMin
	R = lMin: G = lMid: B = lMax
Case 240 To 300
	lMid = (Hue - 240) * Delta + lMin
	R = lMid: G = lMin: B = lMax
Case 300 To 360
	lMid = -(Hue - 360) * Delta + lMin
	R = lMax: G = lMin: B = lMid
End Select
HSLToRGB = B * &H10000 + G * &H100& + R
End Function

Private Function RGBToHSL(ByVal RGBValue As Long) As HSL
Dim R As Long, G As Long, B As Long
Dim lMax As Long, lMin As Long
Dim Delta As Single
R = RGBValue And &HFF
G = (RGBValue And &HFF00&) \ &H100&
B = (RGBValue And &HFF0000) \ &H10000
If R > G Then
	lMax = R: lMin = G
Else
	lMax = G: lMin = R
End If
If B > lMax Then
	lMax = B
ElseIf B < lMin Then
	lMin = B
End If
RGBToHSL.Luminance = lMax * 100 / 255
If lMax > lMin Then
	RGBToHSL.Saturation = (lMax - lMin) * 100 / lMax
	Delta = 60 / (lMax - lMin)
	Select Case lMax
	Case R
	If B > G Then
		RGBToHSL.Hue = Delta * (G - B) + 360
	Else
		RGBToHSL.Hue = Delta * (G - B)
	End If
	Case G
		RGBToHSL.Hue = Delta * (B - R) + 120
	Case B
		RGBToHSL.Hue = Delta * (R - G) + 240
	End Select
End If
End Function

Private Sub cmdGo_Click()
  Dim Color As HSL
  Color = RGBToHSL(Val("&H" & txtRGB.Text))
  For Color.Hue = 0 To 49
	  Picture1(Color.Hue).BackColor = HSLToRGB(Color.Hue, Color.Saturation, Color.Luminance)
  Next Color.Hue
End Sub

Sub form_load()
  Dim colour As Long, red As Byte, green As Byte, blue As Byte
  Dim str As String
	 red = 11
	 green = 22
	 blue = 33
  
  str = "Red : " & red & vbCrLf
  str = str & "Green : " & green & vbCrLf
  str = str & "Blue : " & blue & vbCrLf
  MsgBox str
  colour = RGB(red, green, blue)
  blue = (colour And &HFF0000) \ &H10000
  green = (colour And &HFF00&) \ &H100&
  red = colour And &HFF
  str = "Red : " & red & vbCrLf
  str = str & "Green : " & green & vbCrLf
  str = str & "Blue : " & blue & vbCrLf
  MsgBox str
  txtRGB.Text = RGB(100, 100, 100)  ' colour
End Sub

[MikeAThon]

I don't think it's necessary to convert from HSL coordinates.

I think the problem was that the OP is using modular division instead of shift-followed-by-AND:

colRed = lSourceColor  And &HFF
colGreen = (lSourceColor  / &H100) And &HFF
colBlue = (lSourceColor  / &H10000) And &HFF

See http://www.codeguru.com/forum/showthread.php?t=402310

Mike

[dglienna]

That's why I posted this:

 colour = RGB(red, green, blue)
  blue = (colour And &HFF0000) \ &H10000
  green = (colour And &HFF00&) \ &H100&
  red = colour And &HFF
  str = "Red : " & red & vbCrLf
  str = str & "Green : " & green & vbCrLf
  str = str & "Blue : " & blue & vbCrLf
MsgBox str

[Andrex]

Thanks, but it seems I didn't explain myself correctly. Neither of the functions posted worked.

Let's suppose I have a system color constant such as vbWindowBackground that I want to convert to RGB. All I need is a function to decompose this color to get the values:

Red=255
Green=255
Blue=255

which equals the white background of Windows' objects.

Thanks in advance (and merry christmas, )

[moa]

So ?

Colour is a long which you can express by a long or by a vbcolour or RGB(r,g,b) as you whish !

The valid range for a normal RGB color is 0 to 16,777,215 (&HFFFFFF). The high byte of a number in this range equals 0; the lower 3 bytes, from least to most significant byte, determine the amount of red, green, and blue, respectively. The red, green, and blue components are each represented by a number between 0 and 255 (&HFF). If the high byte isn't 0, Visual Basic uses the system colors, as defined in the user's Control Panel settings and by constants listed in the Visual Basic (VB) object library in the Object Browser.

edit : you may also use the TranslateColor function of the olepro32.dll library

[MikeAThon]

System colors (like vbWindowBackground) are stored differently.

See "Title: RGB values for vbWindowBackground, vbButtonFace" at http://www.experts-exchange.com/Prog..._10205021.html

Mike

[Andrex]

System colors (like vbWindowBackground) are stored differently.

See "Title: RGB values for vbWindowBackground, vbButtonFace" at http://www.experts-exchange.com/Prog..._10205021.html

Mike

Thanks, I finally made it work using that function.