232 lines
8.6 KiB
HTML
Vendored
232 lines
8.6 KiB
HTML
Vendored
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
|
|
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
|
|
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
|
|
<meta name="description" content="Tutorial for tweaking HTML Purifier's Tidy-like behavior." />
|
|
<link rel="stylesheet" type="text/css" href="style.css" />
|
|
|
|
<title>Tidy - HTML Purifier</title>
|
|
|
|
</head><body>
|
|
|
|
<h1>Tidy</h1>
|
|
|
|
<div id="filing">Filed under Development</div>
|
|
<div id="index">Return to the <a href="index.html">index</a>.</div>
|
|
<div id="home"><a href="http://htmlpurifier.org/">HTML Purifier</a> End-User Documentation</div>
|
|
|
|
<p>You've probably heard of HTML Tidy, Dave Raggett's little piece
|
|
of software that cleans up poorly written HTML. Let me say it straight
|
|
out:</p>
|
|
|
|
<p class="emphasis">This ain't HTML Tidy!</p>
|
|
|
|
<p>Rather, Tidy stands for a cool set of Tidy-inspired features in HTML Purifier
|
|
that allows users to submit deprecated elements and attributes and get
|
|
valid strict markup back. For example:</p>
|
|
|
|
<pre><center>Centered</center></pre>
|
|
|
|
<p>...becomes:</p>
|
|
|
|
<pre><div style="text-align:center;">Centered</div></pre>
|
|
|
|
<p>...when this particular fix is run on the HTML. This tutorial will give
|
|
you the lowdown of what exactly HTML Purifier will do when Tidy
|
|
is on, and how to fine-tune this behavior. Once again, <strong>you do
|
|
not need Tidy installed on your PHP to use these features!</strong></p>
|
|
|
|
<h2>What does it do?</h2>
|
|
|
|
<p>Tidy will do several things to your HTML:</p>
|
|
|
|
<ul>
|
|
<li>Convert deprecated elements and attributes to standards-compliant
|
|
alternatives</li>
|
|
<li>Enforce XHTML compatibility guidelines and other best practices</li>
|
|
<li>Preserve data that would normally be removed as per W3C</li>
|
|
</ul>
|
|
|
|
<h2>What are levels?</h2>
|
|
|
|
<p>Levels describe how aggressive the Tidy module should be when
|
|
cleaning up HTML. There are four levels to pick: none, light, medium
|
|
and heavy. Each of these levels has a well-defined set of behavior
|
|
associated with it, although it may change depending on your doctype.</p>
|
|
|
|
<dl>
|
|
<dt>light</dt>
|
|
<dd>This is the <strong>lenient</strong> level. If a tag or attribute
|
|
is about to be removed because it isn't supported by the
|
|
doctype, Tidy will step in and change into an alternative that
|
|
is supported.</dd>
|
|
<dt>medium</dt>
|
|
<dd>This is the <strong>correctional</strong> level. At this level,
|
|
all the functions of light are performed, as well as some extra,
|
|
non-essential best practices enforcement. Changes made on this
|
|
level are very benign and are unlikely to cause problems.</dd>
|
|
<dt>heavy</dt>
|
|
<dd>This is the <strong>aggressive</strong> level. If a tag or
|
|
attribute is deprecated, it will be converted into a non-deprecated
|
|
version, no ifs ands or buts.</dd>
|
|
</dl>
|
|
|
|
<p>By default, Tidy operates on the <strong>medium</strong> level. You can
|
|
change the level of cleaning by setting the %HTML.TidyLevel configuration
|
|
directive:</p>
|
|
|
|
<pre>$config->set('HTML.TidyLevel', 'heavy'); // burn baby burn!</pre>
|
|
|
|
<h2>Is the light level really light?</h2>
|
|
|
|
<p>It depends on what doctype you're using. If your documents are HTML
|
|
4.01 <em>Transitional</em>, HTML Purifier will be lazy
|
|
and won't clean up your <code>center</code>
|
|
or <code>font</code> tags. But if you're using HTML 4.01 <em>Strict</em>,
|
|
HTML Purifier has no choice: it has to convert them, or they will
|
|
be nuked out of existence. So while light on Transitional will result
|
|
in little to no changes, light on Strict will still result in quite
|
|
a lot of fixes.</p>
|
|
|
|
<p>This is different behavior from 1.6 or before, where deprecated
|
|
tags in transitional documents would
|
|
always be cleaned up regardless. This is also better behavior.</p>
|
|
|
|
<h2>My pages look different!</h2>
|
|
|
|
<p>HTML Purifier is tasked with converting deprecated tags and
|
|
attributes to standards-compliant alternatives, which usually
|
|
need copious amounts of CSS. It's also not foolproof: sometimes
|
|
things do get lost in the translation. This is why when HTML Purifier
|
|
can get away with not doing cleaning, it won't; this is why
|
|
the default value is <strong>medium</strong> and not heavy.</p>
|
|
|
|
<p>Fortunately, only a few attributes have problems with the switch
|
|
over. They are described below:</p>
|
|
|
|
<table class="table">
|
|
<thead><tr>
|
|
<th>Element@Attr</th>
|
|
<th>Changes</th>
|
|
</tr></thead>
|
|
<tbody>
|
|
<tr>
|
|
<td>caption@align</td>
|
|
<td>Firefox supports stuffing the caption on the
|
|
left and right side of the table, a feature that
|
|
Internet Explorer, understandably, does not have.
|
|
When align equals right or left, the text will simply
|
|
be aligned on the left or right side.</td>
|
|
</tr>
|
|
<tr>
|
|
<td>img@align</td>
|
|
<td>The implementation for align bottom is good, but not
|
|
perfect. There are a few pixel differences.</td>
|
|
</tr>
|
|
<tr>
|
|
<td>br@clear</td>
|
|
<td>Clear both gets a little wonky in Internet Explorer. Haven't
|
|
really been able to figure out why.</td>
|
|
</tr>
|
|
<tr>
|
|
<td>hr@noshade</td>
|
|
<td>All browsers implement this slightly differently: we've
|
|
chosen to make noshade horizontal rules gray.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<p>There are a few more minor, although irritating, bugs.
|
|
Some older browsers support deprecated attributes,
|
|
but not CSS. Transformed elements and attributes will look unstyled
|
|
to said browsers. Also, CSS precedence is slightly different for
|
|
inline styles versus presentational markup. In increasing precedence:</p>
|
|
|
|
<ol>
|
|
<li>Presentational attributes</li>
|
|
<li>External style sheets</li>
|
|
<li>Inline styling</li>
|
|
</ol>
|
|
|
|
<p>This means that styling that may have been masked by external CSS
|
|
declarations will start showing up (a good thing, perhaps). Finally,
|
|
if you've turned off the style attribute, almost all of
|
|
these transformations will not work. Sorry mates.</p>
|
|
|
|
<p>You can review the rendering before and after of these transformations
|
|
by consulting the <a
|
|
href="http://htmlpurifier.org/live/smoketests/attrTransform.php">attrTransform.php
|
|
smoketest</a>.</p>
|
|
|
|
<h2>I like the general idea, but the specifics bug me!</h2>
|
|
|
|
<p>So you want HTML Purifier to clean up your HTML, but you're not
|
|
so happy about the br@clear implementation. That's perfectly fine!
|
|
HTML Purifier will make accomodations:</p>
|
|
|
|
<pre>$config->set('HTML.Doctype', 'XHTML 1.0 Transitional');
|
|
$config->set('HTML.TidyLevel', 'heavy'); // all changes, minus...
|
|
<strong>$config->set('HTML.TidyRemove', 'br@clear');</strong></pre>
|
|
|
|
<p>That third line does the magic, removing the br@clear fix
|
|
from the module, ensuring that <code><br clear="both" /></code>
|
|
will pass through unharmed. The reverse is possible too:</p>
|
|
|
|
<pre>$config->set('HTML.Doctype', 'XHTML 1.0 Transitional');
|
|
$config->set('HTML.TidyLevel', 'none'); // no changes, plus...
|
|
<strong>$config->set('HTML.TidyAdd', 'p@align');</strong></pre>
|
|
|
|
<p>In this case, all transformations are shut off, except for the p@align
|
|
one, which you found handy.</p>
|
|
|
|
<p>To find out what the names of fixes you want to turn on or off are,
|
|
you'll have to consult the source code, specifically the files in
|
|
<code>HTMLPurifier/HTMLModule/Tidy/</code>. There is, however, a
|
|
general syntax:</p>
|
|
|
|
<table class="table">
|
|
<thead>
|
|
<tr>
|
|
<th>Name</th>
|
|
<th>Example</th>
|
|
<th>Interpretation</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr>
|
|
<td>element</td>
|
|
<td>font</td>
|
|
<td>Tag transform for <em>element</em></td>
|
|
</tr>
|
|
<tr>
|
|
<td>element@attr</td>
|
|
<td>br@clear</td>
|
|
<td>Attribute transform for <em>attr</em> on <em>element</em></td>
|
|
</tr>
|
|
<tr>
|
|
<td>@attr</td>
|
|
<td>@lang</td>
|
|
<td>Global attribute transform for <em>attr</em></td>
|
|
</tr>
|
|
<tr>
|
|
<td>e#content_model_type</td>
|
|
<td>blockquote#content_model_type</td>
|
|
<td>Change of child processing implementation for <em>e</em></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
|
|
<h2>So... what's the lowdown?</h2>
|
|
|
|
<p>The lowdown is, quite frankly, HTML Purifier's default settings are
|
|
probably good enough. The next step is to bump the level up to heavy,
|
|
and if that still doesn't satisfy your appetite, do some fine-tuning.
|
|
Other than that, don't worry about it: this all works silently and
|
|
effectively in the background.</p>
|
|
|
|
</body></html>
|
|
|
|
<!-- vim: et sw=4 sts=4
|
|
-->
|