In pngmath, don't call latex again if an image with the given SHA sum already

exists.

1 files changed, 8 insertions, 0 deletions

diff --git a/sphinx/ext/pngmath.py b/sphinx/ext/pngmath.py
index 08fb93892..77d08eef1 100644
--- a/sphinx/ext/pngmath.py
+++ b/sphinx/ext/pngmath.py
@@ -78,6 +78,8 @@ def render_math(self, math):
     shasum = "%s.png" % sha(math).hexdigest()
     relfn = posixpath.join(self.builder.imgpath, 'math', shasum)
     outfn = path.join(self.builder.outdir, '_images', 'math', shasum)
+    if path.isfile(outfn):
+        return relfn, self.builder.env._pngmath_depth.get(shasum, None)
 
     latex = DOC_HEAD + self.builder.config.pngmath_latex_preamble
     latex += (use_preview and DOC_BODY_PREVIEW or DOC_BODY) % math
@@ -156,10 +158,15 @@ def render_math(self, math):
             m = depth_re.match(line)
             if m:
                 depth = int(m.group(1))
+                self.builder.env._pngmath_depth[shasum] = depth
                 break
 
     return relfn, depth
 
+def ensure_depthcache(app, env):
+    if not hasattr(env, '_pngmath_depth'):
+        env._pngmath_depth = {}
+
 def cleanup_tempdir(app, exc):
     if exc:
         return
@@ -200,4 +207,5 @@ def setup(app):
     app.add_config_value('pngmath_use_preview', False, False)
     app.add_config_value('pngmath_dvipng_args', ['-gamma 1.5', '-D 110'], False)
     app.add_config_value('pngmath_latex_preamble', '', False)
+    app.connect('env-updated', ensure_depthcache)
     app.connect('build-finished', cleanup_tempdir)