def makeExtension(configs=None) :
    return MathExtension()

from markdown.inlinepatterns import Pattern
import markdown, urllib

class MathPattern(Pattern):
    def __init__(self,md):
        Pattern.__init__(self,"\$\$(.*?)\$\$",md)
    def handleMatch(self, m):
            
        texcode=m.group(2)
        el = markdown.util.etree.Element('img')
        el.attrib["src"]="tex.cgi?"+self.unescape(texcode.replace(' ','%20'))
        
        el.attrib["alt"]=self.unescape(texcode)
        el.attrib["class"]='tex'
        return el
        
class MathExtension(markdown.Extension):
    def extendMarkdown(self, md, md_globals):
        md.inlinePatterns.add('math', MathPattern(md), '<image_link')