css - 如何获取使用 ExCSS 解析的 CSS 的十六进制代码
问题描述
我正在使用https://github.com/HockeyJustin/ExCSS_Core（ExCSS 的更新以支持 .NET4）来解析 CSS 文件，目的是提取在其定义中包含颜色引用的选择器的相关部分，无论是它们#、rgb 或 rgba。
例如
.selector {
border: 1px;
background-color: #ccc;
padding: 5px;
}
返回为
.selector {
background-color: #ccc;
}
我已经处理得很好，但是尽我所能将十六进制代码全部转换为rgb，给出
.selector {
background-color: rgb(204,204,204);
}
有人知道以原始格式返回颜色代码的方法吗？
或者，有没有更好的方法来实现这一点？非常感谢！
解决方案
我遇到了同样的问题，使用 ExCSS 并且需要将颜色样式 ( rgb(0,0,0)) 转换为可用格式。我们最终使用了一种自定义方法来尝试将 HTML/CSS 颜色转换为System.Drawing.Color. 下面处理一些我们需要的其他情况，#000000例如blue颜色，rgb(0,0,0)以及上面问题中提到的情况。不保证这符合规范，但似乎足以满足我们的需求（TODO：重构FromHtmlHexUnverified为 main 方法）。
using System.Drawing;
using System.Linq;
/// <summary>
/// Attempts to parse a color described by a CSS style to a standard color object.
/// This will first attempt to parse as a color with a leading "#".
/// If that fails, will check if this is a "rgb(0,0,0)" formatted string.
/// If that fails, will attempt to lookup the value according to standard
/// color definition names ("black", etc).
/// </summary>
/// <param name="value">CSS style color value.</param>
/// <returns>Parsed color.</returns>
public static Color FromCss(string value)
{
var trimmed = value?.Trim() ?? null;
if (string.IsNullOrEmpty(trimmed))
{
// check on trimmed, but throw against value
throw new ArgumentException(nameof(value));
}
int r, g, b;
// try leading hash color
if (trimmed[0] == '#')
{
if (trimmed.Length == 4)
{
// one digit hex values
r = Convert.ToInt32(trimmed.Substring(1, 1), 16);
g = Convert.ToInt32(trimmed.Substring(2, 1), 16);
b = Convert.ToInt32(trimmed.Substring(3, 1), 16);
}
else if (trimmed.Length == 7)
{
// two digit hex values
r = Convert.ToInt32(trimmed.Substring(1, 2), 16);
g = Convert.ToInt32(trimmed.Substring(3, 2), 16);
b = Convert.ToInt32(trimmed.Substring(5, 2), 16);
}
else
{
throw new ArgumentException(nameof(value));
}
var color = Color.FromArgb(r, g, b);
return color;
}
// try rgb(0,0,0) color
else if (trimmed.StartsWith("rgb"))
{
int start = trimmed.IndexOf('(') + 1;
int end = trimmed.IndexOf(')');
if (!(start > 0) || !(end > -1) || (end <= start))
{
throw new ArgumentException(nameof(value));
}
var inner = trimmed.Substring(start, end - start);
var values = inner.Split(",", StringSplitOptions.RemoveEmptyEntries).Select(x => x.Trim()).ToList();
if (!values.Any() || values.Count != 3)
{
throw new ArgumentException(nameof(value));
}
// RGB values are decimal
r = Convert.ToInt32(values[0]);
g = Convert.ToInt32(values[1]);
b = Convert.ToInt32(values[2]);
var color = Color.FromArgb(r, g, b);
return color;
}
// try standard name color
else
{
switch (trimmed.ToLower())
{
/*
* These are "standard"? CSS colors
*/
case "aliceblue": return FromHtmlHexUnverified("#f0f8ff");
case "antiquewhite": return FromHtmlHexUnverified("#faebd7");
case "aqua": return FromHtmlHexUnverified("#00ffff");
case "aquamarine": return FromHtmlHexUnverified("#7fffd4");
case "azure": return FromHtmlHexUnverified("#f0ffff");
case "beige": return FromHtmlHexUnverified("#f5f5dc");
case "bisque": return FromHtmlHexUnverified("#ffe4c4");
case "black": return FromHtmlHexUnverified("#000000");
case "blanchedalmond": return FromHtmlHexUnverified("#ffebcd");
case "blue": return FromHtmlHexUnverified("#0000ff");
case "blueviolet": return FromHtmlHexUnverified("#8a2be2");
case "brown": return FromHtmlHexUnverified("#a52a2a");
case "burlywood": return FromHtmlHexUnverified("#deb887");
case "cadetblue": return FromHtmlHexUnverified("#5f9ea0");
case "chartreuse": return FromHtmlHexUnverified("#7fff00");
case "chocolate": return FromHtmlHexUnverified("#d2691e");
case "coral": return FromHtmlHexUnverified("#ff7f50");
case "cornflowerblue": return FromHtmlHexUnverified("#6495ed");
case "cornsilk": return FromHtmlHexUnverified("#fff8dc");
case "crimson": return FromHtmlHexUnverified("#dc143c");
case "cyan": return FromHtmlHexUnverified("#00ffff");
case "darkblue": return FromHtmlHexUnverified("#00008b");
case "darkcyan": return FromHtmlHexUnverified("#008b8b");
case "darkgoldenrod": return FromHtmlHexUnverified("#b8860b");
case "darkgray": return FromHtmlHexUnverified("#a9a9a9");
case "darkgrey": return FromHtmlHexUnverified("#a9a9a9");
case "darkgreen": return FromHtmlHexUnverified("#006400");
case "darkkhaki": return FromHtmlHexUnverified("#bdb76b");
case "darkmagenta": return FromHtmlHexUnverified("#8b008b");
case "darkolivegreen": return FromHtmlHexUnverified("#556b2f");
case "darkorange": return FromHtmlHexUnverified("#ff8c00");
case "darkorchid": return FromHtmlHexUnverified("#9932cc");
case "darkred": return FromHtmlHexUnverified("#8b0000");
case "darksalmon": return FromHtmlHexUnverified("#e9967a");
case "darkseagreen": return FromHtmlHexUnverified("#8fbc8f");
case "darkslateblue": return FromHtmlHexUnverified("#483d8b");
case "darkslategray": return FromHtmlHexUnverified("#2f4f4f");
case "darkslategrey": return FromHtmlHexUnverified("#2f4f4f");
case "darkturquoise": return FromHtmlHexUnverified("#00ced1");
case "darkviolet": return FromHtmlHexUnverified("#9400d3");
case "deeppink": return FromHtmlHexUnverified("#ff1493");
case "deepskyblue": return FromHtmlHexUnverified("#00bfff");
case "dimgray": return FromHtmlHexUnverified("#696969");
case "dimgrey": return FromHtmlHexUnverified("#696969");
case "dodgerblue": return FromHtmlHexUnverified("#1e90ff");
case "firebrick": return FromHtmlHexUnverified("#b22222");
case "floralwhite": return FromHtmlHexUnverified("#fffaf0");
case "forestgreen": return FromHtmlHexUnverified("#228b22");
case "fuchsia": return FromHtmlHexUnverified("#ff00ff");
case "gainsboro": return FromHtmlHexUnverified("#dcdcdc");
case "ghostwhite": return FromHtmlHexUnverified("#f8f8ff");
case "gold": return FromHtmlHexUnverified("#ffd700");
case "goldenrod": return FromHtmlHexUnverified("#daa520");
case "gray": return FromHtmlHexUnverified("#808080");
case "grey": return FromHtmlHexUnverified("#808080");
case "green": return FromHtmlHexUnverified("#008000");
case "greenyellow": return FromHtmlHexUnverified("#adff2f");
case "honeydew": return FromHtmlHexUnverified("#f0fff0");
case "hotpink": return FromHtmlHexUnverified("#ff69b4");
case "indianred": return FromHtmlHexUnverified("#cd5c5c");
case "indigo": return FromHtmlHexUnverified("#4b0082");
case "ivory": return FromHtmlHexUnverified("#fffff0");
case "khaki": return FromHtmlHexUnverified("#f0e68c");
case "lavender": return FromHtmlHexUnverified("#e6e6fa");
case "lavenderblush": return FromHtmlHexUnverified("#fff0f5");
case "lawngreen": return FromHtmlHexUnverified("#7cfc00");
case "lemonchiffon": return FromHtmlHexUnverified("#fffacd");
case "lightblue": return FromHtmlHexUnverified("#add8e6");
case "lightcoral": return FromHtmlHexUnverified("#f08080");
case "lightcyan": return FromHtmlHexUnverified("#e0ffff");
case "lightgoldenrodyellow": return FromHtmlHexUnverified("#fafad2");
case "lightgray": return FromHtmlHexUnverified("#d3d3d3");
case "lightgrey": return FromHtmlHexUnverified("#d3d3d3");
case "lightgreen": return FromHtmlHexUnverified("#90ee90");
case "lightpink": return FromHtmlHexUnverified("#ffb6c1");
case "lightsalmon": return FromHtmlHexUnverified("#ffa07a");
case "lightseagreen": return FromHtmlHexUnverified("#20b2aa");
case "lightskyblue": return FromHtmlHexUnverified("#87cefa");
case "lightslategray": return FromHtmlHexUnverified("#778899");
case "lightslategrey": return FromHtmlHexUnverified("#778899");
case "lightsteelblue": return FromHtmlHexUnverified("#b0c4de");
case "lightyellow": return FromHtmlHexUnverified("#ffffe0");
case "lime": return FromHtmlHexUnverified("#00ff00");
case "limegreen": return FromHtmlHexUnverified("#32cd32");
case "linen": return FromHtmlHexUnverified("#faf0e6");
case "magenta": return FromHtmlHexUnverified("#ff00ff");
case "maroon": return FromHtmlHexUnverified("#800000");
case "mediumaquamarine": return FromHtmlHexUnverified("#66cdaa");
case "mediumblue": return FromHtmlHexUnverified("#0000cd");
case "mediumorchid": return FromHtmlHexUnverified("#ba55d3");
case "mediumpurple": return FromHtmlHexUnverified("#9370d8");
case "mediumseagreen": return FromHtmlHexUnverified("#3cb371");
case "mediumslateblue": return FromHtmlHexUnverified("#7b68ee");
case "mediumspringgreen": return FromHtmlHexUnverified("#00fa9a");
case "mediumturquoise": return FromHtmlHexUnverified("#48d1cc");
case "mediumvioletred": return FromHtmlHexUnverified("#c71585");
case "midnightblue": return FromHtmlHexUnverified("#191970");
case "mintcream": return FromHtmlHexUnverified("#f5fffa");
case "mistyrose": return FromHtmlHexUnverified("#ffe4e1");
case "moccasin": return FromHtmlHexUnverified("#ffe4b5");
case "navajowhite": return FromHtmlHexUnverified("#ffdead");
case "navy": return FromHtmlHexUnverified("#000080");
case "oldlace": return FromHtmlHexUnverified("#fdf5e6");
case "olive": return FromHtmlHexUnverified("#808000");
case "olivedrab": return FromHtmlHexUnverified("#6b8e23");
case "orange": return FromHtmlHexUnverified("#ffa500");
case "orangered": return FromHtmlHexUnverified("#ff4500");
case "orchid": return FromHtmlHexUnverified("#da70d6");
case "palegoldenrod": return FromHtmlHexUnverified("#eee8aa");
case "palegreen": return FromHtmlHexUnverified("#98fb98");
case "paleturquoise": return FromHtmlHexUnverified("#afeeee");
case "palevioletred": return FromHtmlHexUnverified("#d87093");
case "papayawhip": return FromHtmlHexUnverified("#ffefd5");
case "peachpuff": return FromHtmlHexUnverified("#ffdab9");
case "peru": return FromHtmlHexUnverified("#cd853f");
case "pink": return FromHtmlHexUnverified("#ffc0cb");
case "plum": return FromHtmlHexUnverified("#dda0dd");
case "powderblue": return FromHtmlHexUnverified("#b0e0e6");
case "purple": return FromHtmlHexUnverified("#800080");
case "red": return FromHtmlHexUnverified("#ff0000");
case "rosybrown": return FromHtmlHexUnverified("#bc8f8f");
case "royalblue": return FromHtmlHexUnverified("#4169e1");
case "saddlebrown": return FromHtmlHexUnverified("#8b4513");
case "salmon": return FromHtmlHexUnverified("#fa8072");
case "sandybrown": return FromHtmlHexUnverified("#f4a460");
case "seagreen": return FromHtmlHexUnverified("#2e8b57");
case "seashell": return FromHtmlHexUnverified("#fff5ee");
case "sienna": return FromHtmlHexUnverified("#a0522d");
case "silver": return FromHtmlHexUnverified("#c0c0c0");
case "skyblue": return FromHtmlHexUnverified("#87ceeb");
case "slateblue": return FromHtmlHexUnverified("#6a5acd");
case "slategray": return FromHtmlHexUnverified("#708090");
case "slategrey": return FromHtmlHexUnverified("#708090");
case "snow": return FromHtmlHexUnverified("#fffafa");
case "springgreen": return FromHtmlHexUnverified("#00ff7f");
case "steelblue": return FromHtmlHexUnverified("#4682b4");
case "tan": return FromHtmlHexUnverified("#d2b48c");
case "teal": return FromHtmlHexUnverified("#008080");
case "thistle": return FromHtmlHexUnverified("#d8bfd8");
case "tomato": return FromHtmlHexUnverified("#ff6347");
case "turquoise": return FromHtmlHexUnverified("#40e0d0");
case "violet": return FromHtmlHexUnverified("#ee82ee");
case "wheat": return FromHtmlHexUnverified("#f5deb3");
case "white": return FromHtmlHexUnverified("#ffffff");
case "whitesmoke": return FromHtmlHexUnverified("#f5f5f5");
case "yellow": return FromHtmlHexUnverified("#ffff00");
case "yellowgreen": return FromHtmlHexUnverified("#9acd32");
default: throw new NotSupportedException($"Can not resolve CSS color: {trimmed}");
}
}
}
// convert without safety checks
private static Color FromHtmlHexUnverified(string value)
{
int r, g, b;
r = Convert.ToInt32(value.Substring(1, 2), 16);
g = Convert.ToInt32(value.Substring(3, 2), 16);
b = Convert.ToInt32(value.Substring(5, 2), 16);
var color = Color.FromArgb(r, g, b);
return color;
}
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