ikiwiki/doc/users/jasonblevins.mdwn

[[!meta title="Jason Blevins"]]

I am a former Ikiwiki user who wrote several plugins and patches
related to MathML, [[SVG|todo/svg]], and [[todo/syntax highlighting]].
Some related links and notes are archived below.

Homepage: <http://jblevins.org/>

## Plugins

The following [plugins](http://jblevins.org/projects/ikiwiki/)
are no longer maintained, but please feel free to use, modify, and
redistribute them.  Read the corresponding perldoc documentation for
more details.

 * [mdwn_itex][] - Works with the [[`mdwn`|plugins/mdwn]] plugin to convert
   inline [[todo/LaTeX]] expressions to MathML using `itex2MML`.

 * [h1title][] - If present, use the leading level 1 Markdown header to
   set the page title and remove it from the page body.

 * [code][] - Whole file and inline code snippet [[todo/syntax highlighting]]
   via GNU Source-highlight.  The list of supported file extensions is
   configurable.

 * [metamail][] - a plugin for loading metadata from email-style
   headers at top of a file (e.g., `title: Page Title` or
   `date: November 2, 2008 11:14 EST`).

 * [pandoc][] - [[ikiwiki/Markdown]] page processing via
   [Pandoc](http://johnmacfarlane.net/pandoc/) (a Haskell library for
   converting from one markup format to another).  [[todo/LaTeX]] and
   [[reStructuredText|plugins/rst]] are optional.

 * [path][] - Provides path-specific template conditionals such as
   `IS_HOMEPAGE` and `IN_DIR_SUBDIR`.

 [mdwn_itex]: http://jblevins.org/git/ikiwiki/plugins.git/plain/mdwn_itex.pm
 [h1title]: http://jblevins.org/git/ikiwiki/plugins.git/plain/h1title.pm
 [code]: http://jblevins.org/projects/ikiwiki/code
 [metamail]: http://jblevins.org/git/ikiwiki/plugins.git/plain/metamail.pm
 [pandoc]: http://jblevins.org/git/ikiwiki/plugins.git/plain/pandoc.pm
 [path]: http://jblevins.org/git/ikiwiki/plugins.git/plain/path.pm

## MathML and SVG support

So far, I've made some notes on sanitizing MathML and SVG via
htmlscrubber on the [[todo/svg]] todo item.

I've also worked out some content-negotiation issues.  First of all,
one needs to modify the default templates to use the
XHTML+MathML+SVG doctype (see e.g., this [patch][template-patch]).
For most browsers, the content type of the pages should be
`application/xhtml+xml`.  The solution is easy if you want to
just send `application/xhtml+xml` to everybody:
just change the content type of `.html` files across the board.

However, if you want to support browsers that don't accept
`application/xhtml+xml` (and those that will but say they
don't, such as IE with the MathPlayer plugin), then one
needs a `mod_rewrite` rule like the following:

    RewriteCond %{HTTP_ACCEPT} application\/xhtml\+xml [OR]
    RewriteCond %{HTTP_USER_AGENT} (W3C.*Validator|MathPlayer)
    RewriteRule \.html$ - [T=application/xhtml+xml]

This solves the problem of MathML and inline SVG in static pages
but some additional work is required for dynamically generated
pages, like page previews, that are generated by `ikiwiki.cgi`.
We need to allow `ikiwiki.cgi` to set the content type dynamically
based on the `HTTP_CONTENT_TYPE` environment variable
(e.g., with the following [patch][cgi-patch]).  Then, the following
rewrite rules can pass the correct content type to ikiwiki:

    RewriteCond %{HTTP_ACCEPT} application\/xhtml\+xml [OR]
    RewriteCond %{HTTP_USER_AGENT} (W3C.*Validator|MathPlayer)
    RewriteRule ikiwiki.cgi$ - [T=application/xhtml+xml]

One final critical issue is that a production-ready setup needs to
implement some sort of on-the-fly error handling.  If a user submits
an invalid LaTeX expression or SVG code (not malicious, just invalid)
and saves the page, then browsers like Firefox will halt processing of
the page, preventing any further viewing or editing.  A less than
optimal solution is to force users to preview the page before saving.
That way if someone introduces invalid XHTML then they can't save the
page in the first place (unless they post directly to the right URL).

 [template-patch]: http://jblevins.org/git/ikiwiki.git/commit/?h=xbeta&id=416d5d1b15b94e604442e4e209a30dee4b77b684
 [cgi-patch]: http://jblevins.org/git/ikiwiki.git/commit/?id=fa538c375250ab08f396634135f7d79fce2a9d36