Color to hex

It's not a huge deal anymore to use Hex values for colors in web pages, since Netscape3+ and IE both handle basically the same set of user-friendly color text values, but sometimes we need to feel like getting geeky helps cover the bases.

As with most things on the smithvoice.com sitelett, we found that we were typing this out by memory just often enough to make it tedious yet not often enough that our fingers could do it while we were watching TV. So we put it here for our future cut & pasting, and if it helps you too then so much the better.

Public Class rcsColorUtil
'The FromName will return a
'Color with an rgb value of 0 if 
'the name you provide does not match any
'predefined names. 

'so you don't have to check the IsNamedColor 
'property for safety.  However, if you do want to check you
'have to iterate through a color array which is relatively intensive

Public Shared Function ColorToHex(ByVal Value As Color) As String
   Return InternalColorToHex(Value)
End Function

   
Public Shared Function ColorToHex(ByVal Value As String) As String
   Return InternalColorToHex(Color.FromName(Value))
End Function

Private Shared Function InternalColorToHex(ByVal Value As Color) As String
   Dim hr, hb, hg, fr, fg, fb As String
   hr = Hex(Value.R)
   If Len(hr) = 1 Then
      fr = "0" & hr
   Else
      fr = hr
   End If

   hg = Hex(Value.G)
   If Len(hg) = 1 Then
      fg = "0" & hg
   Else
      fg = hg
   End If

   hb = Hex(Value.B)
   If Len(hb) = 1 Then
      fb = "0" & hb
   Else
      fb = hb
   End If
   Return "#" & fr & fg & fb

End Function


End Class

Pass in a Color or a KnownColor string and the correct overloaded function will pass off to the internal worker function. Because the entry functions are defined as Shared you don't have to instantiate an rcsColorUtil object to do the do. The following will suffice:

MsgBox(rcsColorUtil.ColorToHex("PaleGoldenrod"))

'or...

Dim c As Color = Color.SeaGreen
MsgBox(rcsColorUtil.ColorToHex(c))

As the comment says, there's no need to do a check of [Value].IsNamedColor because passing anything, including Nothing will not throw an exception. If you pass junk to IsNamedColor then the result will still be True and the values of the R, G and B will all be zero.

Personally we wish an exception would be raised for garbage input, making it a bit more logically consistant, but such is life in .Net-land :)

Hope it helps!

Robert Smith
Kirkland, WA

added to smithvoice August 2004