Radiograph is a small Rails plugin to expose Ultraviolet (http://ultraviolet.rubyforge.org/) to Rails views. Ultraviolet is a syntax highlighting library which makes use of Textpow which parses Textmate bundles (whew!). This plugin lets you use Ultraviolet’s syntax highlighting capabilities in Rails applications. It parses a Textmate syntax and generates HTML based on a Textmate theme.

Usage

You can use it in views like so:

  <%= code("show_menu if current_user") %>

The default theme is ‘all_hallows_eve’ and the default syntax is ‘ruby.’ The above snippet would generate some simple XHTML that syntax highlights the code show. If you don’t want to type code(), you can use the convenience alias: c().

  <%= c("my_value ? puts 'Good!' : puts 'Oh noez!'", :theme => 'amy') %>

Note that this example changes the default theme (learn more about the parameters to Radiograph#code in its documentation).

CSS is required

You will also need to require the proper CSS file for the theme(s) you use using the require_syntax_css method.

  <%= require_syntax_css %>

If you’ve used anything other than the default theme (as I did with the ‘amy’ theme above), then you’ll need to link those also.

  <%= require_syntax_css 'amy' %>

You should now have a nicely highlighted block of code on your page. Look at the documentation for the individual methods for more information.

Setting defaults

You can set defaults in environment.rb by setting values on the Radiograph class.

  Radiograph.theme = 'cobalt'
  Radiograph.syntax = 'lisp'

These values will then become the defaults in your application.

Things left…

Here are some things I’d like to add in the future…

• Caching — Ultraviolet is a little slower than I’d like…it may be Oniguruma’s fault. Caching would alleviate some of the problem.
• Asset hosts — Right now the CSS is just dumped into your public/ folder; I’d like to hook into Rails and use whatever the app is using.