Color.FromArgb(r, g, b).ToKnownColor()

I was going through the code of CSAH when I came across the class HtmlColor.  It does a mapping of r, g, b colors to a name by doing this:

this.color = String.Format("#{0:x2}{1:x2}{2:x2}", r, g, b);

switch (this.color)

{

    case "#00ffff":

        this.color = "aqua";

        break;

    case "#000000":

        this.color = "black";

        break;

        // more code

 

I tried this:

Enum.GetName(typeof(KnownColor), Color.FromArgb(255, r, g, b).ToKnownColor());

 

Nope.. didn't work!  ToKnownColor() was returning zero.  A quick lookup in MSDN Documentation proved my worst fears.  Unless you create a Color FromName, ToKnownColor() will return zero!

I googled and found this solution.  Here's my improved(?) version:

Dictionary<int, string> colorCache = new Dictionary<int, string>();

public string GetKnownColorName(int r, int g, int b)

{

    int iArgb = Color.FromArgb(r, g, b).ToArgb();

    if (this.colorCache.ContainsKey(iArgb)) 

        return this.colorCache[iArgb];

    string namedColor = null;

    foreach (string name in Enum.GetNames(typeof(KnownColor)))

    {

        Color kc = Color.FromName(name);

        if (!kc.IsSystemColor && kc.ToArgb() == iArgb)

        {

            namedColor = kc.Name;

            this.colorCache.Add(iArgb, namedColor);

            break;

        }

    }

    return namedColor;

}

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