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.

Solution 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 HexConverter(System.Drawing.Color c)
{
    return "#" + c.R.ToString("X2") + c.G.ToString("X2") + c.B.ToString("X2");
}

private static String RGBConverter(System.Drawing.Color c)
{
    return "RGB(" + c.R.ToString() + "," + c.G.ToString() + "," + c.B.ToString() + ")";
}

Solution 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);

Solution 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}";

    public 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

Solution 4

e.g.

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

This can avoid the KnownColor trick.

Solution 5

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);
}

View more solutions

Comments

[samgak]

@Rod stackoverflow.com/questions/20750062/…

[Nazmul]

But if I do this way, Color red = System.Drawing.Color.Red; string redHex = ColorTranslator.ToHtml(red); it does not provide the Hex Value.

[Troy Hunt]

Certainly should do, I tested that code specifically and got #"FF0000". What are you getting? You might also like to refer to the MSDN reference: msdn.microsoft.com/en-us/library/…

[Nazmul]

Try with Color red = System.Drawing.Color.Red; --> it does not provide #FF0000.

[Troy Hunt]

So using exactly the first code block I provided, what is the value of redHex? I think something on your side is missing.

[Nazmul]

The code you have provided works but when I change the first line of your code to : Color red = System.Drawing.Color.Red; --> Then it does not give the hex code. It gives "Red" as an output.

[anon]

@Hoque - Confirmed. ColorTranslator gives a "friendly" name to the color. How annoying!

[JMD]

I'd go so far as to say that empty try-catch blocks should (almost) universally be eradicated. They have great potential to lead to buggy code, if not now then down the road when this code is modified. Still, +1 for the cleaned up code, and to the OP +1 for a well-framed question.

[zacharydl]

Took me a while to find the VB equivelant: String.Format("#{0:X2}{1:X2}{2:X2}", c.R, c.G, c.B)

[Brad]

+1 bc this caused me to look at the .NET implementation of ColorTranslator which is the accepted answer + KnownColor logic. i didn't want that logic, so i went with the accepted answer (but made extension methods)

[mike]

This may not be suitable for some cases, because a quick test within a WinForm lead to the following result: System.Drawing.ColorTranslator.ToHtml(Me.BackColor) = "buttonface" instead of the (desired) hex value.

[aloisdg]

I post an adaptation of your code to C#6 as an alternative answer. You can see it here.

[Mohammed Noureldin]

I belive it should be Hex2, not Hex, otherwise the color maybe wrong interpolated.

[User1]

@MohammedNoureldin Where would Hex2 go in the code, I have seen colours being slightly different sometimes?

[Mohammed Noureldin]

I meant X2 instead of X, otherwise you might get 1 instead of 01 then it will be a problem.

[LarryBud]

This will produce the wrong color if the color has an alpha channel (transparency). You will get full opaqueness.

[Ari Roth]

@LarryBud Absolutely true, and thank you for pointing it out. My example skipped the alpha channel only because I was keying off of the original question, which also didn't include it. :)

[ProfK]

@MohammedNoureldin Yeah, with X2 then you don't need all the color.B.ToString("X").Length == 1 ? ternaries.

[Shockwaver]

So clean... +1!

[George Fabish]

To make this work with web browsers I had to switch the formatting so that the alpha parameter would be added last.