hurrah! equations in latex and html

TODO: center images in html
TODO: track equations in a database?

1 files changed, 129 insertions, 0 deletions

diff --git a/bn_django/git_wiki/latex_directive.py b/bn_django/git_wiki/latex_directive.py
new file mode 100644
index 0000000..823cc6a
--- /dev/null
+++ b/bn_django/git_wiki/latex_directive.py
@@ -0,0 +1,129 @@
+"""
+Implement latex directive.
+
+"""
+import os
+import shutil
+import sha
+import tempfile
+import subprocess
+
+from docutils import nodes
+from docutils.parsers.rst.directives import register_directive, flag
+from docutils.parsers.rst.roles import register_canonical_role
+
+from settings import *
+
+dorawtexstuff = False
+
+def latex_math(tex,centerize=False):
+    """ Process `tex` and produce image nodes. """
+    if not dorawtexstuff:
+        image_names = latex_snippet_to_png(tex)
+        the_nodes = []
+        alt = tex
+        styleclasses = ("equation",)
+        if tex[:2] =='$$':
+            centerize=True
+        if centerize:
+            styleclasses += ("centered-equ",)
+        for pageno, name in enumerate(image_names):
+            the_nodes.append(nodes.image(uri=name, alt=alt, 
+                                classes=styleclasses,))
+            alt = ''
+        return the_nodes
+    else:
+        return [nodes.raw(tex,tex,format='latex')]
+
+def latex_directive(name, arguments, options, content, lineno,
+                    content_offset, block_text, state, state_machine):
+    """ Latex directive. """
+    tex = '\n'.join(content)
+    return latex_math(tex)
+latex_directive.content = True
+
+
+def latex_role(role, rawtext, text, lineno, inliner,
+               options={}, content=[]):
+    """ Latex role. """
+    i = rawtext.find('`')
+    tex = rawtext[i+1:-1]
+    return latex_math(tex,), []
+
+def register():
+    register_directive('latex', latex_directive)
+    register_canonical_role('latex', latex_role)
+    register_canonical_role('m', latex_role)
+
+def call_command_in_dir(app, args, targetdir):
+
+    cwd = os.getcwd()
+    try:
+        os.chdir(targetdir)
+        #print args
+        #print ' '.join(args)
+        p = subprocess.Popen(app + ' ' + ' '.join(args), shell=True)
+        sts = os.waitpid(p.pid, 0)
+
+        # FIXME -- should we raise an exception of status is non-zero?
+        
+    finally:
+        # Restore working directory
+        os.chdir(cwd)
+
+latex_template = r'''
+\documentclass[12pt]{article}
+\pagestyle{empty}
+%(prologue)s
+\begin{document}
+%(raw)s
+\end{document}
+'''
+max_pages = 10
+MAX_RUN_TIME = 5 # seconds
+latex_name_template = 'latex2png_%s'
+latex = "latex"
+dvipng = "dvipng"
+latex_args = ("--interaction=nonstopmode", "%s.tex")
+dvipng_args = ("-q", "-bgTransparent", "-Ttight", "--noghostscript", "-l%s" % max_pages, "%s.dvi")
+
+def latex_snippet_to_png(inputtex, prologue=''):
+    """ Convert a latex snippet into a png. """
+    import shutil
+    
+    tex = latex_template % { 'raw': inputtex, 'prologue': prologue }
+    namebase = latex_name_template % sha.new(tex).hexdigest()
+    dst = namebase + '%d.png'
+
+    tmpdir = tempfile.mkdtemp()
+    try:
+        data = open("%s/%s.tex" % (tmpdir, namebase), "w")
+        data.write(tex)
+        data.close()
+        args = list(latex_args)
+        args[-1] = args[-1] % namebase
+        res = call_command_in_dir(latex, args, tmpdir)
+        if not res is None:
+            # FIXME need to return some sort of error
+            return []
+        args = list(dvipng_args)
+        args[-1] = args[-1] % namebase
+        res = call_command_in_dir(dvipng, args, tmpdir)
+        if not res is None:
+            # FIXME need to return some sort of error
+            return []
+
+        page = 1
+        pagenames = []
+        while os.access("%s/%s%d.png" % (tmpdir, namebase, page), os.R_OK):
+            pagename = dst % page
+            shutil.copyfile("%s/%s%d.png" % (tmpdir, namebase, page), 
+                EQU_FOLDER + pagename)
+            page += 1
+            pagenames.append(EQU_PREFIX + pagename)
+    finally:
+        # FIXME do some tidy up here
+        pass
+    shutil.rmtree(tmpdir)
+    return pagenames
+