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Changed Hex2Color algorithm

I'm not sure that this is the most optimal Hex2Dec2Color code around, but it will do me for the time being. I ended up writing a tool to wrap that following function so that I could easily enter a Hex string and see the color representation of it.

    Dim c As Color = Color.FromArgb( _
            ByteFromHexString("#88A8B2", 0), _
            ByteFromHexString("#88A8B2", 2), _
            ByteFromHexString("#88A8B2", 4) _
        )


    Private Function ByteFromHexString(ByVal hexStrng As String, ByVal rgb As Byte) As Byte
        If Microsoft.VisualBasic.Left(hexStrng, 1) = "#" Then
            hexStrng = Mid(hexStrng, 2)
        End If
        hexStrng = UCase(hexStrng)

        Dim _hex As String = "0123456789ABCDEF"
        Dim iOut As Byte
        Try
            iOut = CByte((_hex.IndexOf(hexStrng.Chars(rgb + 1)) * 16))
            iOut += CByte((_hex.IndexOf(hexStrng.Chars(rgb))))
        Catch ex As System.OverflowException
        Catch ex As System.IndexOutOfRangeException
            ' bad formatted hexstring
        End Try
        Return iOut
    End Function
I must admit that I was amazed that I couldn't find a Hex2Dec method in the BCL though!











3 Comments


  • 

    

    
Er...Byte.Parse()? 
    

    

    

    

    

    
A simple example (in C#, without error-checking): 
    

    

    

    

    

    
using System; 
    

    

    
using System.Drawing; 
    

    

    
using System.Globalization; 
    

    

    

    

    

    
class Test 
    

    

    
{ 
    

    

    
	static void Main() 
    

    

    
	{ 
    

    

    
		string hexString = "#88A8B2"; 
    

    

    
		Color color = ConvertHexStringToColor(hexString); 
    

    

    
		Console.WriteLine(color); 
    

    

    
	} 
    

    

    

    

    

    
	static Color ConvertHexStringToColor(string hexString) 
    

    

    
	{ 
    

    

    
		Int32 colorValue = Int32.Parse(hexString.Substring(1), NumberStyles.AllowHexSpecifier); 
    

    

    

    

    

    
		return Color.FromArgb(colorValue); 
    

    

    
	} 
    

    

    
} 
    

    

    

    

    

    
Jim 
    

    


    

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  • 

    

    

    

    

    
Oops, Int32.Parse of course, not Byte... 
    

    

    

    

    

    
Remember that the Alpha channel of a color constructed from this will default to 0. 
    

    

    

    

    

    
Also, the reason there isn't a built-in method to do this is probably because '#' isn't the standard way to denote prefix numbers ('0x' is more common). 
    

    

    

    

    

    
Jim 
    

    


    

    • 

  • 

    

    
Or even Microsoft.VisualBasic.Hex("123") 
    

    


    

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