EnigmaCurry · April 17, 2011 15:23 · Apr 17, 2011 · Apr 17, 2011 · Apr 17, 2011 · Apr 17, 2011
diff --git a/blogofile_latex_filter.py → latex.py b/blogofile_latex_filter.py → latex.py
diff --git a/blogofile_latex.py → blogofile_latex_filter.py b/blogofile_latex.py → blogofile_latex_filter.py
@@ -1,5 +1,7 @@
 """
 Render TeX blocks to png
+
+This is a Blogofile filter. Place it in your _filters directory.
 """
 import tempfile
 import subprocess

diff --git a/sample_post.markdown → sample_post b/sample_post.markdown → sample_post
diff --git a/sample_post.markdown b/sample_post.markdown
@@ -0,0 +1,21 @@
+---
+categories: Category 1, Category 2
+date: 2009/07/24 16:20:00
+title: Sample LaTeX post
+filter: latex, markdown
+tags: test, blogofile, cool-stuff
+author: Ryan
+---
+This is a sample post with TeX blocks.
+
+This is a TeX block:
+$$latex
+y = \int_0^\infty \gamma^2 \cos(x) dx $ this is after the block.
+
+This is an inline Tex block: $$latex \cos(x) $ and this is after.
+
+This is two seperate inline Tex blocks: $$latex \sin(x) $ and then $$latex \tan(x) $ and this is after.
+
+This is a mistyped TeX block because I didn't terminate it properly. $$latex \tan(x)$ and this text is rendered too because I didn't put a space before the dollar sign $
+
+This is a broken TeX block because I didn't put a space before it$$latex \tan(x) $
diff --git a/blogofile_latex.py b/blogofile_latex.py
@@ -0,0 +1,106 @@
+"""
+Render TeX blocks to png
+"""
+import tempfile
+import subprocess
+import shutil
+import shlex
+import os
+import re
+import hashlib
+import blogofile_bf as bf
+
+tex_template = r"""
+\documentclass{article}
+\usepackage{amsmath}
+\usepackage{amsthm}
+\usepackage{amssymb}
+\usepackage{bm}
+\newcommand{\mx}[1]{\mathbf{\bm{#1}}}
+\newcommand{\vc}[1]{\mathbf{\bm{#1}}}
+\newcommand{\T}{\text{T}}
+\pagestyle{empty}
+\begin{document}
+%s
+\newpage 
+\end{document}
+"""
+
+latex_block_re = re.compile(r"\s\$\$latex\s(.*?)\s\$", re.DOTALL)
+
+def render_tex_math_expr_to_png(math_block, png_location):
+    """Wrap a mathematical TeX expression in $ symbols and render"""
+    render_tex_to_png("$%s$" % math_block, png_location)
+
+def render_tex_to_png(latex_block, png_location):
+    """Render a TeX formatted string to an image file
+
+    Depends on 'latex' and 'dvipng' binaries on the system path
+    """
+
+    #Create a temporary directory and go into it
+    tmp_dir = tempfile.mkdtemp()
+    previous_dir = os.getcwd()
+    os.chdir(tmp_dir)
+
+    tex_f = open(os.path.join(tmp_dir,"source.tex"),"w")
+    tex_f.write((tex_template % latex_block))
+    tex_f.close()
+
+    try:
+        #Generate the .dvi
+        p = subprocess.Popen(shlex.split(
+                'latex -interaction=nonstopmode source.tex'),
+                             stdout=subprocess.PIPE)
+        p.wait()
+        #Generate the .ps
+        p = subprocess.Popen(shlex.split('dvips source.dvi'),
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        p.wait()
+        #Generate the .png
+        p = subprocess.Popen(shlex.split(
+                'convert -density 120 -trim -transparent'
+                ' "#FFFFFF" source.ps rendered.png'),stdout=subprocess.PIPE)
+        p.wait()
+        #Copy the .png to the png_location
+        os.chdir(previous_dir)
+        shutil.copyfile(os.path.join(tmp_dir,"rendered.png"),png_location)
+    finally:
+        #Go back to the original directory and clean up the temp files
+        os.chdir(previous_dir)
+        shutil.rmtree(tmp_dir)
+
+def render_latex_blocks(src, cache_dir="_tmp", site_images_dir="images"):
+    """Render a document with LaTeX blocks
+
+    1) Extract all the $$latex blocks
+    2) Render each TeX block to an image to the cache
+    3) Copy the (pre)rendered image from the cache to the _site dir
+    4) Replace the $$latex blocks with <img> tags
+    """
+    img_substitutions = {}
+    for m in latex_block_re.finditer(src):
+        tex_expr = m.groups()[0]
+        fn = hashlib.md5(tex_expr).hexdigest()+".png"
+        png_cached = os.path.join(cache_dir,fn)
+        site_png_dir = bf.util.path_join("_site",bf.util.fs_site_path_helper(
+                site_images_dir))
+        site_png = bf.util.path_join(site_png_dir,fn)
+        #only render the image if the image is not already cached
+        if(not os.path.isfile(png_cached)):
+            bf.util.mkdir(cache_dir)
+            bf.filter.logger.info("Rendering LaTeX: "+tex_expr)
+            render_tex_math_expr_to_png(tex_expr,png_cached)
+        #copy the rendered image to the site dir
+        bf.util.mkdir(site_png_dir)
+        shutil.copyfile(png_cached,site_png)
+        #record the $$latex block and it's replacement <img> tag
+        img_substitutions[m.group()] = "<img src=\"%s\">" % \
+            (bf.util.site_path_helper(site_images_dir,fn))
+    #Make the <img> tag replacements in a single pass
+    p = re.compile('|'.join(map(re.escape, img_substitutions)))
+    return p.sub(lambda x: img_substitutions[x.group(0)], src)
+
+def run(src):
+    return render_latex_blocks(src)