= Using HTML in Wiki Text =

Trac supports inserting HTML into any wiki context, accomplished using the `#!html` [wiki:WikiProcessors WikiProcessor]. 

However a constraint is that this HTML has to be well-formed.
In particular you can't insert a start tag in an `#!html` block,
resume normal wiki text and insert the corresponding end tag in a 
second `#!html` block. 

Fortunately, for creating styled <div>s, <span>s  or even complex tables
containing arbitrary Wiki text, there's a powerful alternative: use of
dedicated `#!div`, `#!span` and `#!table`, `#!tr`, `#!td` and `#!th` blocks.

Those Wiki processors are built-in, and does not require installing any additional packages.

== How to Use `#!html` == #HowtoUseHTML
To inform the wiki engine that a block of text should be treated as HTML, use the ''html'' processor. 

||= Wiki Markup =||= Display =||
{{{#!td
  {{{
  {{{
  #!html
  <h1 style="text-align: right; color: blue">HTML Test</h1>
  }}}
  }}}
}}}
{{{#!td style="padding-left: 2em"
  {{{
  #!html
  <h1 style="text-align: right; color: blue">HTML Test</h1>
  }}}
}}}

Note that Trac sanitizes your HTML code before displaying it. That means that if you try to use potentially dangerous constructs such as Javascript event handlers, those will be removed from the output. 

Since 0.11, the filtering is done by Genshi, and as such, the produced output will be a well-formed fragment of HTML. As noted above in the introduction, this mean that you can no longer use two HTML blocks, one for opening a <div>, the second for closing it, in order to wrap arbitrary wiki text.
The new way to wrap any wiki content inside a <div> is to use the `#!div` Wiki  processor.

== How to Use `#!div` and `#!span` == #HowtoUseDivSpan

||= Wiki Markup =||= Display =||
{{{#!td
  {{{
  {{{
  #!div class=important style="border: 2pt solid; text-align: center"
  This is the ''only'' way to go in Trac 0.11
  }}}
  }}}
}}}
{{{#!td style="padding-left: 2em"
  {{{
  #!div class=important style="border: 2pt solid; text-align: center"
  This is the ''only'' way to go in Trac 0.11
  }}}
}}}

Note that the contents of a `#!div` block are contained in one or more paragraphs, which have a non-zero top and bottom margin by default. This leads to the top and bottom padding in the example above. To remove the top and bottom margin of the contents, add the `compact` class to the `#!div`.

For spans, you should rather use the Macro call syntax:
||= Wiki Markup =||= Display =||
{{{#!td
  {{{
  Hello 
  [[span(''WORLD'' (click [#anchor here]), style=color: green; font-size: 120%, id=anchor)]]!
  }}}
}}}
|---------------------------------------------------------------------------------
||= Display =||
{{{#!td style="padding-left: 2em"
  Hello
  [[span(''WORLD'' (click [#anchor here]), style=color: green; font-size: 120%, id=anchor)]]!
}}}


== HTML comments ==
HTML comments are stripped from the output of the `html` processor. To add an HTML comment to a wiki page, use the `htmlcomment` processor (available since 0.12). For example, the following code block:
||= Wiki Markup =||
{{{#!td
  {{{
  {{{
  #!htmlcomment
  This block is translated to an HTML comment.
  It can contain <tags> and &entities; that will not be escaped in the output.
  }}}
  }}}
}}}
|---------------------------------------------------------------------------------
||= Display =||
{{{#!td
  {{{
  <!--
  This block is translated to an HTML comment.
  It can contain <tags> and &entities; that will not be escaped in the output.
  -->
  }}}
}}}

Please note that the character sequence "--" is not allowed in HTML comments, and will generate a rendering error.


== More Information ==

 * http://www.w3.org/ -- World Wide Web Consortium
 * http://www.w3.org/MarkUp/ -- HTML Markup Home Page

----
See also:  WikiProcessors, WikiFormatting, WikiRestructuredText