转换的.Net颜色对象为十六进制codeS和返回 [英] Convert .Net Color Objects to HEX codes and Back

问题描述

按问题的标题，我怎么会拿一个十六进制code，并将其转换为.NET Color对象，做它的其他方式？

As per the question title, How could I take a hex code and convert it to a .Net Color object, and do it the other way?

我用Google搜索，并不断收到不相同的方式工作。

I googled and keep getting the same way which doesn't work.

 ColorTranslator.ToHtml(renderedChart.ForeColor)

这将返回，而不是#FFFFFF颜色的名字如白！做它的其他方式似乎有奇怪的结果，唯一的工作在某些时候...

Which returns the name of the color as in 'White' instead of '#ffffff'! Doing it the other way seems to have odd results, only working some of the time...

推荐答案

是这样的：

Color color = Color.Red;
string colorString = string.Format("#{0:X2}{1:X2}{2:X2}",
    color.R, color.G, color.B);

做它的另一种方法是有点复杂，因为＃F00是一个有效的HTML颜色（指全红），但它仍然是可行的使用正则表达式，这里是一个小样本的类：

Doing it the other way is a little more complex as #F00 is a valid html color (meaning full red) but it is still doable using regex, here is a small sample class :

using System;
using System.Diagnostics;
using System.Drawing;
using System.Text.RegularExpressions;
using System.Collections.Generic;

public static class HtmlColors
{
    public static string ToHtmlHexadecimal(this Color color)
    {
        return string.Format("#{0:X2}{1:X2}{2:X2}", color.R, color.G, color.B);
    }

    static Regex htmlColorRegex = new Regex(
        @"^#((?'R'[0-9a-f]{2})(?'G'[0-9a-f]{2})(?'B'[0-9a-f]{2}))"
        + @"|((?'R'[0-9a-f])(?'G'[0-9a-f])(?'B'[0-9a-f]))$",
        RegexOptions.Compiled | RegexOptions.IgnoreCase);

    public static Color FromHtmlHexadecimal(string colorString)
    {
        if (colorString == null)
        {
            throw new ArgumentNullException("colorString");
        }

        var match = htmlColorRegex.Match(colorString);
        if (!match.Success)
        {
            var msg = "The string \"{0}\" doesn't represent"
            msg += "a valid HTML hexadecimal color";
            msg = string.Format(msg, colorString);

            throw new ArgumentException(msg,
                "colorString");
        }

        return Color.FromArgb(
            ColorComponentToValue(match.Groups["R"].Value),
            ColorComponentToValue(match.Groups["G"].Value),
            ColorComponentToValue(match.Groups["B"].Value));
    }

    static int ColorComponentToValue(string component)
    {
        Debug.Assert(component != null);
        Debug.Assert(component.Length > 0);
        Debug.Assert(component.Length <= 2);

        if (component.Length == 1)
        {
            component += component;
        }

        return int.Parse(component,
            System.Globalization.NumberStyles.HexNumber);
    }
}

用法：

// Display #FF0000
Console.WriteLine(Color.Red.ToHtmlHexadecimal());

// Display #00FF00
Console.WriteLine(HtmlColors.FromHtmlHexadecimal("#0F0").ToHtmlHexadecimal());

// Display #FAF0FE
Console.WriteLine(HtmlColors.FromHtmlHexadecimal("#FAF0FE").ToHtmlHexadecimal());

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