Convert System.Drawing.Color to RGB and Hex Value

问题

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.

回答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() + ")";
}

回答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);

回答3:

If you can use C#6, 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.

回答4:

e.g.

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

This can avoid the KnownColor trick.

回答5:

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

回答6:

For hexadecimal code try this

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

For RGB one

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);
}

来源：https://stackoverflow.com/questions/2395438/convert-system-drawing-color-to-rgb-and-hex-value

标签

ASP.NET

rgb

system.drawing.color