Add MathJax support.

Readme.org

@@ -2,7 +2,7 @@
 #+Author: Yujie Wen
 #+Email: yjwen.ty@gmail.com
 
-#+OPTIONS: reveal_center:nil
+#+OPTIONS: reveal_center:nil reveal_progress:t reveal_history:nil reveal_control:t reveal_mathjax:t
 #+REVEAL_TRANS: cube
 #+REVEAL_THEME: moon
 #+REVEAL_HLEVEL: 2
@@ -198,7 +198,7 @@ $ git clone https://github.com/yjwen/org-reveal.git
    - reveal-progress : Show/hide progress bar.
    - reveal-history : Enable/disable slide history track.
    - reveal-center : Enable/disable slide centering.
-
+     
 *** Configure Plug-ins
 
     Each plug-ins can be set on/off by adding =#+OPTIONS= tags or
@@ -227,13 +227,30 @@ $ git clone https://github.com/yjwen/org-reveal.git
    If you saw odd indentation, please set variable =org-html-indent=
    to =nil= and export again.
 
+** MathJax
+
+   ${n! \over k!(n-k)!} = {n \choose k}$
+
+   LateX equation are renderred in native HTML5 contents.
+
+ *IMPORTANT*: Displaying equations requires internet connection to
+   [[mathjax.org]] or local MathJax installation.
+
+ *IMPORTANT 2*: MathJax is disabled by default to reduce internet
+   traffic. Set =#+OPTIONS= tag =reveal_mathjax= or variable
+ =org-reveal-mathjax= to true to enable it. For local MathJax
+   installation, set option =REVEAL_MATH_JAX_URL= to pointing to the
+   installation location.
+   
 * Thanks
 
   Courtesy to:
 
 #+ATTR_REVEAL: :frag roll-in
-  the powerful Org-mode, 
+  The powerful Org-mode, 
 #+ATTR_REVEAL: :frag roll-in
-  and the impressive Reveal.js
+  the impressive Reveal.js
+#+ATTR_REVEAL: :frag roll-in
+  and the precise MathJax
 
   

ox-reveal.el

@@ -40,6 +40,8 @@
    (:reveal-trans "REVEAL_TRANS" nil org-reveal-transition t)
    (:reveal-theme "REVEAL_THEME" nil org-reveal-theme t)
    (:reveal-hlevel "REVEAL_HLEVEL" nil nil t)
+   (:reveal-mathjax nil "reveal_mathjax" org-reveal-mathjax t)
+   (:reveal-mathjax-url "REVEAL_MATHJAX_URL" nil org-reveal-mathjax-url t)
    )
 
   :translate-alist
@@ -97,20 +99,31 @@ can be include."
   :type 'string)
 
 (defcustom org-reveal-progress t
-  "Reveal progress applit."
+  "Reveal progress applet."
   :group 'org-export-reveal
   :type 'boolean)
 
 (defcustom org-reveal-history t
-  "Reveal history applit."
+  "Reveal history applet."
   :group 'org-export-reveal
   :type 'boolean)
 
 (defcustom org-reveal-center t
-  "Reveal center applit."
+  "Reveal center applet."
   :group 'org-export-reveal
   :type 'boolean)
 
+(defcustom org-reveal-mathjax nil
+  "Enable MathJax script."
+  :group 'org-export-reveal
+  :type 'boolean)
+
+(defcustom org-reveal-mathjax-url
+  "http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"
+  "Default MathJax URL."
+  :group 'org-export-reveal
+  :type 'string)
+
 (defun if-format (fmt val)
   (if val (format fmt val) ""))
 
@@ -229,7 +242,7 @@ to form a legal path name."
 
   
 (defun org-reveal-stylesheets (info)
-  "Return the HTML contents for decalaring reveal stylesheets
+  "Return the HTML contents for declaring reveal stylesheets
 using custom variable `org-reveal-root'."
   (let* ((root-path (plist-get info :reveal-root))
          (css-dir-name (org-reveal--append-path root-path "css"))
@@ -238,9 +251,15 @@ using custom variable `org-reveal-root'."
          (theme-path (org-reveal--append-path css-dir-name "theme"))
          (theme-full (org-reveal--append-path theme-path theme-file)))
     (format "<link rel=\"stylesheet\" href=\"%s\">
-    <link rel=\"stylesheet\" href=\"%s\" id=\"theme\">"
+    <link rel=\"stylesheet\" href=\"%s\" id=\"theme\">\n"
                 min-css-file-name theme-full)))
 
+(defun org-reveal-mathjax-scripts (info)
+  "Return the HTML contents for declaring MathJax scripts"
+  (if (plist-get info :reveal-mathjax)
+      ;; MathJax enabled.
+      (format "<script type=\"text/javascript\" src=\"%s\"></script>\n"
+              (plist-get info :reveal-mathjax-url))))
 
 (defun org-reveal-scripts (info)
   "Return the necessary scripts for initializing reveal.js using
@@ -404,6 +423,7 @@ info is a plist holding export options."
    (if-format "<meta name=\"description\" content=\"%s\"/>\n" (plist-get info :description))
    (if-format "<meta name=\"keywords\" content=\"%s\"/>\n" (plist-get info :keywords))
    (org-reveal-stylesheets info)
+   (org-reveal-mathjax-scripts info)
    "</head>
 <body>
 <div class=\"reveal\">