doc/filter-rewrite-style-attributes.html - incubator-pagespeed-website - Git at Google

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 <html>
   <head>
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <title>Rewrite Style Attributes</title>
     <link rel="stylesheet" href="doc.css">
   </head>
   <body>
 <!--#include virtual="_header.html" -->


   <div id=content>
 <h1>Rewrite Style Attributes</h1>


 <h2>Configuration</h2>
 <p>
 The 'Rewrite Style Attributes' filter is enabled by specifying <em>either</em>:
 <dl>
   <dt>Apache:<dd><pre class="prettyprint"
      >ModPagespeedEnableFilters rewrite_style_attributes,rewrite_css</pre>
   <dt>Nginx:<dd><pre class="prettyprint"
      >pagespeed EnableFilters rewrite_style_attributes,rewrite_css;</pre>
 </dl>
 or
 <dl>
   <dt>Apache:<dd><pre class="prettyprint"
      >ModPagespeedEnableFilters rewrite_style_attributes_with_url,rewrite_css,rewrite_images</pre>
   <dt>Nginx:<dd><pre class="prettyprint"
      >pagespeed EnableFilters rewrite_style_attributes_with_url,rewrite_css,rewrite_images;</pre>
 </dl>
 <p>
 in the configuration file. If both are enabled,
 <code>rewrite_style_sttributes</code> takes precedence.
 </p>
 <h2>Description</h2>
 <p>
 The "Rewrite Style Attributes" filter rewrites CSS inside elements' style
 attribute.  It requires <code>rewrite_css</code> to also be enabled.  See the settings for
 <a href="filter-css-rewrite.html">rewrite_css</a> to control CSS minification, image rewriting,
 image recompression, and cache extension.</p>
 <p>
 <code>rewrite_style_attributes</code> enables the filter for all style
 attributes.  <code>rewrite_style_attributes_with_url</code> enables it only
 for style attributes that contain the text '<code>url(</code>', for which you will generally
 want to enable one or more image optimization filters.</p>
 <p>
 <code>rewrite_style_attributes_with_url</code> is more efficient because it
 does not always parse the CSS, but it will not optimize CSS that doesn't
 reference any URLs. <code>rewrite_style_attributes</code> will always parse
 the CSS and optimize everything possible. Because images are generally the
 source for greatest improvement and are enclosed in <code>url()</code>,
 <code>rewrite_style_attributes_with_url</code> is a good balance for most uses,
 while <code>rewrite_style_attributes</code> is available for more aggressive
 optimization.
 </p>
 <h2>Operation</h2>
 <p>
 This filter inspects the style attributes of all tags other than
 <code>&lt;style&gt;</code> (since they cannot have a style attribute) and
 rewrites them according to the configured <a href="filter-css-rewrite.html"
 >rewrite_css</a> filter, which can include CSS minification, image rewriting,
 image recompression, and cache extension.
 </p>
 <p>
 As explained above, if <code>rewrite_style_attributes_with_url</code> is
 enabled the style attribute's contents are first scanned to ensure that they
 contain the text <code>url(</code> and are processed only if so.
 </p>
 <p>
 For example, if a <code>&lt;div&gt;</code> tag looks like this:
 </p>
 <pre class="prettyprint">
 &lt;div style=&quot;background-image: url('images/Puzzle.jpg');&quot;/&gt;
 </pre>
 <p>
 Then, if the image is optimizable, PageSpeed will convert it to something
 like:
 <pre class="prettyprint">
 &lt;div style=&quot;background-image:url('images/Puzzle.jpg.pagespeed.ic.7X5cYtoCx-.jpg');&quot;/&gt;
 </pre>
 <h3>Example</h3>
 <p>
 You can see the filter in action at <code>www.modpagespeed.com</code> on this
 <a href="https://www.modpagespeed.com/examples/rewrite_style_attributes.html?ModPagespeed=on&amp;ModPagespeedFilters=rewrite_style_attributes_with_url,rewrite_css,rewrite_images">example</a>.
 </p>

 <h2>Risks</h2>
 <p>
 This filter is considered minimal risk.
 <code>rewrite_style_attributes_with_url</code> is a core filter but
 <code>rewrite_style_attributes</code> is not.
 </p>


   </div>
   <!--#include virtual="_footer.html" -->
   </body>
 </html>
	<!--
	Licensed to the Apache Software Foundation (ASF) under one
	or more contributor license agreements. See the NOTICE file
	distributed with this work for additional information
	regarding copyright ownership. The ASF licenses this file
	to you under the Apache License, Version 2.0 (the
	"License"); you may not use this file except in compliance
	with the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing,
	software distributed under the License is distributed on an
	"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	KIND, either express or implied. See the License for the
	specific language governing permissions and limitations
	under the License.
	-->

	<html>
	<head>
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>Rewrite Style Attributes</title>
	<link rel="stylesheet" href="doc.css">
	</head>
	<body>
	<!--#include virtual="_header.html" -->


	<div id=content>
	<h1>Rewrite Style Attributes</h1>



	<h2>Configuration</h2>
	<p>
	The 'Rewrite Style Attributes' filter is enabled by specifying <em>either</em>:
	<dl>
	<dt>Apache:<dd><pre class="prettyprint"
	>ModPagespeedEnableFilters rewrite_style_attributes,rewrite_css</pre>
	<dt>Nginx:<dd><pre class="prettyprint"
	>pagespeed EnableFilters rewrite_style_attributes,rewrite_css;</pre>
	</dl>
	or
	<dl>
	<dt>Apache:<dd><pre class="prettyprint"
	>ModPagespeedEnableFilters rewrite_style_attributes_with_url,rewrite_css,rewrite_images</pre>
	<dt>Nginx:<dd><pre class="prettyprint"
	>pagespeed EnableFilters rewrite_style_attributes_with_url,rewrite_css,rewrite_images;</pre>
	</dl>
	<p>
	in the configuration file. If both are enabled,
	<code>rewrite_style_sttributes</code> takes precedence.
	</p>
	<h2>Description</h2>
	<p>
	The "Rewrite Style Attributes" filter rewrites CSS inside elements' style
	attribute. It requires <code>rewrite_css</code> to also be enabled. See the settings for
	<a href="filter-css-rewrite.html">rewrite_css</a> to control CSS minification, image rewriting,
	image recompression, and cache extension.</p>
	<p>
	<code>rewrite_style_attributes</code> enables the filter for all style
	attributes. <code>rewrite_style_attributes_with_url</code> enables it only
	for style attributes that contain the text '<code>url(</code>', for which you will generally
	want to enable one or more image optimization filters.</p>
	<p>
	<code>rewrite_style_attributes_with_url</code> is more efficient because it
	does not always parse the CSS, but it will not optimize CSS that doesn't
	reference any URLs. <code>rewrite_style_attributes</code> will always parse
	the CSS and optimize everything possible. Because images are generally the
	source for greatest improvement and are enclosed in <code>url()</code>,
	<code>rewrite_style_attributes_with_url</code> is a good balance for most uses,
	while <code>rewrite_style_attributes</code> is available for more aggressive
	optimization.
	</p>
	<h2>Operation</h2>
	<p>
	This filter inspects the style attributes of all tags other than
	<code><style></code> (since they cannot have a style attribute) and
	rewrites them according to the configured <a href="filter-css-rewrite.html"
	>rewrite_css</a> filter, which can include CSS minification, image rewriting,
	image recompression, and cache extension.
	</p>
	<p>
	As explained above, if <code>rewrite_style_attributes_with_url</code> is
	enabled the style attribute's contents are first scanned to ensure that they
	contain the text <code>url(</code> and are processed only if so.
	</p>
	<p>
	For example, if a <code><div></code> tag looks like this:
	</p>
	<pre class="prettyprint">
	<div style="background-image: url('images/Puzzle.jpg');"/>
	</pre>
	<p>
	Then, if the image is optimizable, PageSpeed will convert it to something
	like:
	<pre class="prettyprint">
	<div style="background-image:url('images/Puzzle.jpg.pagespeed.ic.7X5cYtoCx-.jpg');"/>
	</pre>
	<h3>Example</h3>
	<p>
	You can see the filter in action at <code>www.modpagespeed.com</code> on this
	<a href="https://www.modpagespeed.com/examples/rewrite_style_attributes.html?ModPagespeed=on&ModPagespeedFilters=rewrite_style_attributes_with_url,rewrite_css,rewrite_images">example</a>.
	</p>

	<h2>Risks</h2>
	<p>
	This filter is considered minimal risk.
	<code>rewrite_style_attributes_with_url</code> is a core filter but
	<code>rewrite_style_attributes</code> is not.
	</p>


	</div>
	<!--#include virtual="_footer.html" -->
	</body>
	</html>