将.Net Color Objects转换为HEX代码并返回

Question

根据问题标题,我如何获取十六进制代码并将其转换为.Net Color对象,并以其他方式执行？

我用Google搜索并继续采用不起作用的相同方式.

 ColorTranslator.ToHtml(renderedChart.ForeColor)

返回颜色的名称,如'White'而不是'#ffffff'!从另一个方面来看似乎有奇怪的结果,只在某些时候工作......

Answer 1

就像是 :

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

另一方面这样做有点复杂,因为#F00是一个有效的html颜色(意思是全红色),但它仍然可以使用正则表达式,这里是一个小样本类:

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());

Answer 2

"白色" 是有效的HTML颜色.请看ColorTranslator.ToHtml:

此方法将Color结构转换为HTML颜色的字符串表示形式.这是常用的颜色名称,例如"红色","蓝色"或"绿色",而不是数字颜色值的字符串表示,例如"FF33AA".

如果您的颜色无法映射到HTML颜色字符串,则此方法将返回颜色的有效十六进制.看这个例子:

using System;
using System.Drawing;

class Program
{
    static void Main()
    {
        Console.WriteLine(ColorTranslator.ToHtml(Color.White));
        Console.WriteLine(ColorTranslator.ToHtml(Color.FromArgb(32,67,89)));
    }
}