implemented rendering of math ($…$) in HTML via MathJax

bibtexbrowser.php

@@ -56,6 +56,11 @@ function bibtexbrowser_configure($key, $value) {
 @define('BIBLIOGRAPHYSTYLE','DefaultBibliographyStyle');// this is the name of a function
 @define('BIBLIOGRAPHYSECTIONS','DefaultBibliographySections');// this is the name of a function
 @define('BIBLIOGRAPHYTITLE','DefaultBibliographyTitle');// this is the name of a function
+
+// shall we load MathJax to render math in $…$ in HTML?
+@define('BIBTEXBROWSER_RENDER_MATH', true);
+@define('MATHJAX_URI', '//cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS_HTML.js');
+
 // can we load bibtex files on external servers?
 @define('BIBTEXBROWSER_LOCAL_BIB_ONLY', true);
 
@@ -879,6 +884,13 @@ function char2html_case_sensitive($line,$latexmodifier,$char,$entitiyfragment) {
  */
 function latex2html($line) {
 
+  $line = preg_replace('/([^\\\\])~/','\\1 ', $line);
+
+  // performance increases with this test
+  // bug found by Serge Barral: what happens if we have curly braces only (typically to ensure case in Latex)
+  // added && strpos($line,'{')===false
+  if (strpos($line,'\\')===false && strpos($line,'{')===false) return $line;
+
   $maths = array();
   $index = 0;
   // first we escape the math env
@@ -889,13 +901,6 @@ function latex2html($line) {
     $index++;
   }
 
-  $line = preg_replace('/([^\\\\])~/','\\1 ', $line);
-
-  // performance increases with this test
-  // bug found by Serge Barral: what happens if we have curly braces only (typically to ensure case in Latex)
-  // added && strpos($line,'{')===false
-  if (strpos($line,'\\')===false && strpos($line,'{')===false) return $line;
-
   // we should better replace this before the others
   // in order not to mix with the HTML entities coming after (just in case)
   $line = str_replace('\\&','&', $line);
@@ -2318,6 +2323,19 @@ $('a.biburl').each(function() { // for each url "[bibtex]"
 } // end function javascript
 
 
+if (!function_exists('javascript_math')) {
+  function javascript_math() {
+    ?>
+    <script type="text/x-mathjax-config">
+      MathJax.Hub.Config({
+        tex2jax: {inlineMath: [["$","$"]]}
+      });
+    </script>
+    <script src="<?php echo MATHJAX_URI ?>"></script>
+    <?php
+  }
+}
+
 
 /** is used for creating menus (by type, by year, by author, etc.).
 usage:
@@ -3703,6 +3721,10 @@ if (method_exists($content, 'getTitle')) {
   if (BIBTEXBROWSER_USE_PROGRESSIVE_ENHANCEMENT) {
     javascript();
   }
+
+  if (BIBTEXBROWSER_RENDER_MATH) {
+    javascript_math();
+  }
 ?>
 </body>
 </html>