Convert tex formula into google chart API format (Jekyll/Octopress plugin)

googlechart_tex.rb

# Convert tex formula into google chart API format (Jekyll/Octopress plugin)
#
# Usage: {% gctex tex_formula %}
#
# Author: yag_ays (yanagi.ayase [at] gmail.com)
# blog: http://yagays.github.com/
#
# Ref: http://d.hatena.ne.jp/repose/20110506/1304612242

require "cgi"

module Jekyll
  class GoogleChartTexTag < Liquid::Tag

    def initialize(tag_name, text, tokens)
      super
      @text = text
    end

    def render(context)
      "![#{@text}](http://chart.apis.google.com/chart?cht=tx&chl=#{CGI.escape(@text)})"
    end
  end
end

Liquid::Template.register_tag('gctex', Jekyll::GoogleChartTexTag)