我需要从 c# 中的样式表中内联 css。
就像这是如何工作的。
http://www.mailchimp.com/labs/inlinecss.php
CSS 很简单，只有类，没有花哨的选择器。
我正在考虑使用正则表达式(?<rule>(?<selector>[^{}]+){(?<style>[^{}]+)})+从 css 中删除规则，然后尝试在调用类的位置进行简单的字符串替换，但是一些 html 元素已经有一个样式标签，所以我必须考虑到这一点好。
有没有更简单的方法？或者已经用c#编写的东西？
更新 - 2010 年 9 月 16 日
只要您的 html 也是有效的 xml，我就能够想出一个简单的 CSS 内联器。它使用正则表达式来获取<style />元素中的所有样式。然后将 css 选择器转换为 xpath 表达式，并在任何预先存在的内联样式之前将样式内联添加到匹配元素。
请注意，CssToXpath 没有完全实现，有些事情它还不能做......
CssInliner.cs
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Xml.Linq;
using System.Xml.XPath;
namespace CssInliner
{
public class CssInliner
{
private static Regex _matchStyles = new Regex("\\s*(?<rule>(?<selector>[^{}]+){(?<style>[^{}]+)})",
RegexOptions.IgnoreCase
| RegexOptions.CultureInvariant
| RegexOptions.IgnorePatternWhitespace
| RegexOptions.Compiled
);
public List<Match> Styles { get; private set; }
public string InlinedXhtml { get; private set; }
private XElement XhtmlDocument { get; set; }
public CssInliner(string xhtml)
{
XhtmlDocument = ParseXhtml(xhtml);
Styles = GetStyleMatches();
foreach (var style in Styles)
{
if (!style.Success)
return;
var cssSelector = style.Groups["selector"].Value.Trim();
var xpathSelector = CssToXpath.Transform(cssSelector);
var cssStyle = style.Groups["style"].Value.Trim();
foreach (var element in XhtmlDocument.XPathSelectElements(xpathSelector))
{
var inlineStyle = element.Attribute("style");
var newInlineStyle = cssStyle + ";";
if (inlineStyle != null && !string.IsNullOrEmpty(inlineStyle.Value))
{
newInlineStyle += inlineStyle.Value;
}
element.SetAttributeValue("style", newInlineStyle.Trim().NormalizeCharacter(';').NormalizeSpace());
}
}
XhtmlDocument.Descendants("style").Remove();
InlinedXhtml = XhtmlDocument.ToString();
}
private List<Match> GetStyleMatches()
{
var styles = new List<Match>();
var styleElements = XhtmlDocument.Descendants("style");
foreach (var styleElement in styleElements)
{
var matches = _matchStyles.Matches(styleElement.Value);
foreach (Match match in matches)
{
styles.Add(match);
}
}
return styles;
}
private static XElement ParseXhtml(string xhtml)
{
return XElement.Parse(xhtml);
}
}
}
CssToXpath.cs
using System.Text.RegularExpressions;
namespace CssInliner
{
public static class CssToXpath
{
public static string Transform(string css)
{
#region Translation Rules
// References: http://ejohn.org/blog/xpath-css-selectors/
// http://code.google.com/p/css2xpath/source/browse/trunk/src/css2xpath.js
var regexReplaces = new[] {
// add @ for attribs
new RegexReplace {
Regex = new Regex(@"\[([^\]~\$\*\^\|\!]+)(=[^\]]+)?\]", RegexOptions.Multiline),
Replace = @"[@$1$2]"
},
// multiple queries
new RegexReplace {
Regex = new Regex(@"\s*,\s*", RegexOptions.Multiline),
Replace = @"|"
},
// , + ~ >
new RegexReplace {
Regex = new Regex(@"\s*(\+|~|>)\s*", RegexOptions.Multiline),
Replace = @"$1"
},
//* ~ + >
new RegexReplace {
Regex = new Regex(@"([a-zA-Z0-9_\-\*])~([a-zA-Z0-9_\-\*])", RegexOptions.Multiline),
Replace = @"$1/following-sibling::$2"
},
new RegexReplace {
Regex = new Regex(@"([a-zA-Z0-9_\-\*])\+([a-zA-Z0-9_\-\*])", RegexOptions.Multiline),
Replace = @"$1/following-sibling::*[1]/self::$2"
},
new RegexReplace {
Regex = new Regex(@"([a-zA-Z0-9_\-\*])>([a-zA-Z0-9_\-\*])", RegexOptions.Multiline),
Replace = @"$1/$2"
},
// all unescaped stuff escaped
new RegexReplace {
Regex = new Regex(@"\[([^=]+)=([^'|""][^\]]*)\]", RegexOptions.Multiline),
Replace = @"[$1='$2']"
},
// all descendant or self to //
new RegexReplace {
Regex = new Regex(@"(^|[^a-zA-Z0-9_\-\*])(#|\.)([a-zA-Z0-9_\-]+)", RegexOptions.Multiline),
Replace = @"$1*$2$3"
},
new RegexReplace {
Regex = new Regex(@"([\>\+\|\~\,\s])([a-zA-Z\*]+)", RegexOptions.Multiline),
Replace = @"$1//$2"
},
new RegexReplace {
Regex = new Regex(@"\s+\/\/", RegexOptions.Multiline),
Replace = @"//"
},
// :first-child
new RegexReplace {
Regex = new Regex(@"([a-zA-Z0-9_\-\*]+):first-child", RegexOptions.Multiline),
Replace = @"*[1]/self::$1"
},
// :last-child
new RegexReplace {
Regex = new Regex(@"([a-zA-Z0-9_\-\*]+):last-child", RegexOptions.Multiline),
Replace = @"$1[not(following-sibling::*)]"
},
// :only-child
new RegexReplace {
Regex = new Regex(@"([a-zA-Z0-9_\-\*]+):only-child", RegexOptions.Multiline),
Replace = @"*[last()=1]/self::$1"
},
// :empty
new RegexReplace {
Regex = new Regex(@"([a-zA-Z0-9_\-\*]+):empty", RegexOptions.Multiline),
Replace = @"$1[not(*) and not(normalize-space())]"
},
// |= attrib
new RegexReplace {
Regex = new Regex(@"\[([a-zA-Z0-9_\-]+)\|=([^\]]+)\]", RegexOptions.Multiline),
Replace = @"[@$1=$2 or starts-with(@$1,concat($2,'-'))]"
},
// *= attrib
new RegexReplace {
Regex = new Regex(@"\[([a-zA-Z0-9_\-]+)\*=([^\]]+)\]", RegexOptions.Multiline),
Replace = @"[contains(@$1,$2)]"
},
// ~= attrib
new RegexReplace {
Regex = new Regex(@"\[([a-zA-Z0-9_\-]+)~=([^\]]+)\]", RegexOptions.Multiline),
Replace = @"[contains(concat(' ',normalize-space(@$1),' '),concat(' ',$2,' '))]"
},
// ^= attrib
new RegexReplace {
Regex = new Regex(@"\[([a-zA-Z0-9_\-]+)\^=([^\]]+)\]", RegexOptions.Multiline),
Replace = @"[starts-with(@$1,$2)]"
},
// != attrib
new RegexReplace {
Regex = new Regex(@"\[([a-zA-Z0-9_\-]+)\!=([^\]]+)\]", RegexOptions.Multiline),
Replace = @"[not(@$1) or @$1!=$2]"
},
// ids
new RegexReplace {
Regex = new Regex(@"#([a-zA-Z0-9_\-]+)", RegexOptions.Multiline),
Replace = @"[@id='$1']"
},
// classes
new RegexReplace {
Regex = new Regex(@"\.([a-zA-Z0-9_\-]+)", RegexOptions.Multiline),
Replace = @"[contains(concat(' ',normalize-space(@class),' '),' $1 ')]"
},
// normalize multiple filters
new RegexReplace {
Regex = new Regex(@"\]\[([^\]]+)", RegexOptions.Multiline),
Replace = @" and ($1)"
},
};
#endregion
foreach (var regexReplace in regexReplaces)
{
css = regexReplace.Regex.Replace(css, regexReplace.Replace);
}
return "//" + css;
}
}
struct RegexReplace
{
public Regex Regex;
public string Replace;
}
}
还有一些测试
[TestMethod]
public void TestCssToXpathRules()
{
var translations = new Dictionary<string, string>
{
{ "*", "//*" },
{ "p", "//p" },
{ "p > *", "//p/*" },
{ "#foo", "//*[@id='foo']" },
{ "*[title]", "//*[@title]" },
{ ".bar", "//*[contains(concat(' ',normalize-space(@class),' '),' bar ')]" },
{ "div#test .note span:first-child", "//div[@id='test']//*[contains(concat(' ',normalize-space(@class),' '),' note ')]//*[1]/self::span" }
};
foreach (var translation in translations)
{
var expected = translation.Value;
var result = CssInliner.CssToXpath.Transform(translation.Key);
Assert.AreEqual(expected, result);
}
}
[TestMethod]
public void HtmlWithMultiLineClassStyleReturnsInline()
{
#region var html = ...
var html = XElement.Parse(@"<html>
<head>
<title>Hello, World Page!</title>
<style>
.redClass {
background: red;
color: purple;
}
</style>
</head>
<body>
<div class=""redClass"">Hello, World!</div>
</body>
</html>").ToString();
#endregion
#region const string expected ...
var expected = XElement.Parse(@"<html>
<head>
<title>Hello, World Page!</title>
</head>
<body>
<div class=""redClass"" style=""background: red; color: purple;"">Hello, World!</div>
</body>
</html>").ToString();
#endregion
var result = new CssInliner.CssInliner(html);
Assert.AreEqual(expected, result.InlinedXhtml);
}
还有更多测试，但是，它们为输入和预期输出导入 html 文件，我没有发布所有这些！
但我应该发布规范化扩展方法！
private static readonly Regex NormalizeSpaceRegex = new Regex(@"\s{2,}", RegexOptions.None);
public static string NormalizeSpace(this string data)
{
return NormalizeSpaceRegex.Replace(data, @" ");
}
public static string NormalizeCharacter(this string data, char character)
{
var normalizeCharacterRegex = new Regex(character + "{2,}", RegexOptions.None);
return normalizeCharacterRegex.Replace(data, character.ToString());
}