Convert System.Drawing.Color to RGB and Hex Value

Question

Using C# I was trying to develop the following two. The way I am doing it may have some problem and need your kind advice. In addition, I dont know whether there is any existing method to do the same.

private static String HexConverter(System.Drawing.Color c)
{
    String rtn = String.Empty;
    try
    {
        rtn = "#" + c.R.ToString("X2") + c.G.ToString("X2") + c.B.ToString("X2");
    }
    catch (Exception ex)
    {
        //doing nothing
    }

    return rtn;
}

private static String RGBConverter(System.Drawing.Color c)
{
    String rtn = String.Empty;
    try
    {
        rtn = "RGB(" + c.R.ToString() + "," + c.G.ToString() + "," + c.B.ToString() + ")";
    }
    catch (Exception ex)
    {
        //doing nothing
    }

    return rtn;
}

Thanks.

Answer 1

I'm failing to see the problem here. The code looks good to me.

The only thing I can think of is that the try/catch blocks are redundant -- Color is a struct and R, G, and B are bytes, so c can't be null and c.R.ToString(), c.G.ToString(), and c.B.ToString() can't actually fail (the only way I can see them failing is with a NullReferenceException, and none of them can actually be null).

You could clean the whole thing up using the following:

private static String ToHex(System.Drawing.Color c)
    => $"#{c.R:X2}{c.G:X2}{c.B:X2}"
    
private static String ToRGB(System.Drawing.Color c)
    => $"RGB({c.R},{c.G},{c.B})"

Answer 2

You could keep it simple and use the native color translator:

Color red = ColorTranslator.FromHtml("#FF0000");
string redHex = ColorTranslator.ToHtml(red);

Then break the three color pairs into integer form:

int value = int.Parse(hexValue, System.Globalization.NumberStyles.HexNumber);

Answer 3

If you can use C#6 or higher, you can benefit from Interpolated Strings and rewrite @Ari Roth's solution like this:

C# 6:

public static class ColorConverterExtensions
{
    public static string ToHexString(this Color c) => $"#{c.R:X2}{c.G:X2}{c.B:X2}";

    public static string ToRgbString(this Color c) => $"RGB({c.R}, {c.G}, {c.B})";
}

Also:

• I add the keyword this to use them as extensions methods.
• We can use the type keyword string instead of the class name.
• We can use lambda syntax.
• I rename them to be more explicit for my taste.

Edit: If you want to support the alpha channel:

public static class ColorConverterExtensions
{
    // #RRGGBB
    public static string ToHexString(this Color c) => $"#{c.R:X2}{c.G:X2}{c.B:X2}";

    // RGB(R, G, B)
    public static string ToRgbString(this Color c) => $"RGB({c.R}, {c.G}, {c.B})";

    // #RRGGBBAA
    public static string ToHexaString(this Color c) => $"#{c.R:X2}{c.G:X2}{c.B:X2}{c.A:X2}";

    private static double ToProportion(byte b) => b / (double)Byte.MaxValue;

    // RGBA(R, G, B, A)
    public static string ToRgbaString(this Color c) => $"RGBA({c.R}, {c.G}, {c.B}, {ToProportion(c.A):N2})";
}

Fun fact: I have to search about the proportion name, because we want for a value in the interval [0, 1] not a percent which is in the interval [0, 100]

• https://english.stackexchange.com/a/286524/70403
• https://english.stackexchange.com/questions/218655/a-number-between-0-and-1-like-a-percentage-but-expressed-as-a-decimal
• https://math.stackexchange.com/questions/890617/name-for-percentage-as-a-decimal-between-0-and-1-inclusive
• https://math.stackexchange.com/questions/1626783/is-there-a-name-for-numbers-between-0-and-1

Answer 4

I found an extension method that works quite well

public static string ToHex(this Color color)
{
    return String.Format("#{0}{1}{2}{3}"
        , color.A.ToString("X").Length == 1 ? String.Format("0{0}", color.A.ToString("X")) : color.A.ToString("X")
        , color.R.ToString("X").Length == 1 ? String.Format("0{0}", color.R.ToString("X")) : color.R.ToString("X")
        , color.G.ToString("X").Length == 1 ? String.Format("0{0}", color.G.ToString("X")) : color.G.ToString("X")
        , color.B.ToString("X").Length == 1 ? String.Format("0{0}", color.B.ToString("X")) : color.B.ToString("X"));
}

Ref: https://social.msdn.microsoft.com/Forums/en-US/4c77ba6c-6659-4a46-920a-7261dd4a15d0/how-to-convert-rgba-value-into-its-equivalent-hex-code?forum=winappswithcsharp

Answer 5

e.g.

 ColorTranslator.ToHtml(Color.FromArgb(Color.Tomato.ToArgb()))

This can avoid the KnownColor trick.

Answer 6

For hexadecimal code try this

1. Get ARGB (Alpha, Red, Green, Blue) representation for the color
2. Filter out Alpha channel: & 0x00FFFFFF
3. Format out the value (as hexadecimal "X6" for hex)

For RGB one

1. Just format out Red, Green, Blue values

Implementation

private static string HexConverter(Color c) {
  return String.Format("#{0:X6}", c.ToArgb() & 0x00FFFFFF);
}

public static string RgbConverter(Color c) {
  return String.Format("RGB({0},{1},{2})", c.R, c.G, c.B);
}