google charts math tag fallback

lib/wikicloth/extensions/math.rb

@@ -7,25 +7,30 @@ class MathExtension < Extension
       blahtex_png_path = @options[:blahtex_png_path] || '/tmp'
       blahtex_options = @options[:blahtex_options] || '--texvc-compatible-commands --mathml-version-1-fonts --disallow-plane-1 --spacing strict'
 
-      if File.exists?(blahtex_path)
+      if File.exists?(blahtex_path) && @options[:math_formatter] != :google
         begin
+          # pass tex markup to blahtex
           response = `echo '#{buffer.element_content}' | #{blahtex_path} #{blahtex_options} --png --mathml --png-directory #{blahtex_png_path}`
           xml_response = REXML::Document.new(response).root
 
           if @options[:blahtex_html_prefix]
+            # render as embedded image
             file_md5 = xml_response.elements["png/md5"].text
             return "<img src=\"#{File.join(@options[:blahtex_html_prefix],"#{file_md5}.png")}\" />"
           else
+            # render as mathml
             html = xml_response.elements["mathml/markup"].text
             return "<math xmlns=\"http://www.w3.org/1998/Math/MathML\">#{xml_response.elements["mathml/markup"].children.to_s}</math>"
           end
         rescue => err
+          # blahtex error
           return "<span class=\"error\">#{I18n.t("unable to parse mathml", :error => err)}</span>"
         end
       else
-        return "<span class=\"error\">#{I18n.t("blahtex binary not found", :path => blahtex_path)}</span>"
+        # if blahtex does not exist fallback to google charts api
+        encoded_string = URI.escape(buffer.element_content, Regexp.new("[^#{URI::PATTERN::UNRESERVED}]"))
+        return "<img src=\"https://chart.googleapis.com/chart?cht=tx&chl=#{encoded_string}\" />"
       end
-
     end
 
   end