Support Mathjax version 4

Added support for Mathjax version 4 and updated documentation

Author: albert-github

src/config.xml

@@ -2800,14 +2800,16 @@ obfuscate email addresses.
       </docs>
       <value name="MathJax_2"/>
       <value name="MathJax_3"/>
+      <value name="MathJax_4"/>
     </option>
     <option type='enum' id='MATHJAX_FORMAT' defval='HTML-CSS' depends='USE_MATHJAX'>
       <docs>
 <![CDATA[
  When MathJax is enabled you can set the default output format to be used for
  the MathJax output.
- For more details about the output format see <a href="http://docs.mathjax.org/en/v2.7-latest/output.html">MathJax version 2</a>
- and <a href="http://docs.mathjax.org/en/latest/web/components/output.html">MathJax version 3</a>.
+ For more details about the output format see <a href="https://docs.mathjax.org/en/v2.7/output.html">MathJax version 2</a>,
+ <a href="https://docs.mathjax.org/en/v3.2/output/index.html">MathJax version 3</a>
+ and <a href="https://docs.mathjax.org/en/v4.0/output/index.htm">MathJax version 4</a>.
 ]]>
       </docs>
       <value name="HTML-CSS" desc="(which is slower, but has the best compatibility. This is the name for Mathjax version 2, for MathJax version 3 this will be translated into \c chtml)"/>
@@ -2819,33 +2821,42 @@ obfuscate email addresses.
       <docs>
 <![CDATA[
  When MathJax is enabled you need to specify the location relative to the
- HTML output directory using the \c MATHJAX_RELPATH option. The destination
+ HTML output directory using the \c MATHJAX_RELPATH option. For Mathjax version 2 the destination
  directory should contain the `MathJax.js` script. For instance, if the \c mathjax
  directory is located at the same level as the HTML output directory, then
- \c MATHJAX_RELPATH should be <code>../mathjax</code>. The default value points to
+ \c MATHJAX_RELPATH should be <code>../mathjax</code>.s
+ For Mathjax versions 3 and 3 the destination directory should contain the
+ `tex-<format>.js` script (where `<format>` is either `chtml` or `svg`).
+ The default value points to
  the MathJax Content Delivery Network so you can quickly see the result without
  installing MathJax.  However, it is strongly recommended to install a local
  copy of MathJax from https://www.mathjax.org before deployment.
 
  The default value is:
- - in case of  MathJax version 2: https://cdn.jsdelivr.net/npm/mathjax@2
- - in case of  MathJax version 3: https://cdn.jsdelivr.net/npm/mathjax@3
+ - in case of MathJax version 2: https://cdn.jsdelivr.net/npm/mathjax@2
+ - in case of MathJax version 3: https://cdn.jsdelivr.net/npm/mathjax@3
+ - in case of MathJax version 4: https://cdn.jsdelivr.net/npm/mathjax@4
 ]]>
       </docs>
     </option>
     <option type='list' id='MATHJAX_EXTENSIONS' format='string' depends='USE_MATHJAX'>
       <docs>
 <![CDATA[
  The \c MATHJAX_EXTENSIONS tag can be used to specify one or more MathJax extension
- names that should be enabled during MathJax rendering. For example for MathJax version 2
- (see https://docs.mathjax.org/en/v2.7-latest/tex.html#tex-and-latex-extensions):
+ names that should be enabled during MathJax rendering. 
+For example for MathJax version 2 (see https://docs.mathjax.org/en/v2.7/tex.html):
 \verbatim
 MATHJAX_EXTENSIONS     = TeX/AMSmath TeX/AMSsymbols
 \endverbatim
-For example for MathJax version 3 (see http://docs.mathjax.org/en/latest/input/tex/extensions/index.html):
+For example for MathJax version 3 (see https://docs.mathjax.org/en/v3.2/input/tex/extensions/):
 \verbatim
 MATHJAX_EXTENSIONS     = ams
 \endverbatim
+For example for MathJax version 4 (see https://docs.mathjax.org/en/v4.0/input/tex/extensions/):
+\verbatim
+MATHJAX_EXTENSIONS     = units
+\endverbatim
+Note that for Matjax version 4 quite a few extensions are already automatically loaded.
 ]]>
       </docs>
     </option>
@@ -2854,9 +2865,10 @@ MATHJAX_EXTENSIONS     = ams
 <![CDATA[
  The \c MATHJAX_CODEFILE tag can be used to specify a file with JavaScript
  pieces of code that will be used on startup of the MathJax code.
- See
-<a href="http://docs.mathjax.org/en/v2.7-latest/output.html">the MathJax site</a>
- for more details.
+ See the Mathjax site for more details:
+ - <a href="https://docs.mathjax.org/en/v2.7/">MathJax version 2</a>
+ - <a href="https://docs.mathjax.org/en/v3.2/">MathJax version 3</a>
+ - <a href="https://docs.mathjax.org/en/v4.0/">MathJax version 4</a>
 ]]>
       </docs>
       <docs doxywizard='0' doxyfile='0'>

src/configimpl.l

@@ -1839,19 +1839,26 @@ void Config::checkAndCorrect(bool quiet, const bool check)
   {
     auto mathJaxFormat = Config_getEnum(MATHJAX_FORMAT);
     auto mathjaxVersion = Config_getEnum(MATHJAX_VERSION);
-    if (mathjaxVersion == MATHJAX_VERSION_t::MathJax_2)
+    switch (mathjaxVersion)
     {
-      if (mathJaxFormat==MATHJAX_FORMAT_t::chtml)
-      {
-        Config_updateEnum(MATHJAX_FORMAT,MATHJAX_FORMAT_t::HTML_CSS);
-      }
-    }
-    else
-    {
-      if (mathJaxFormat==MATHJAX_FORMAT_t::HTML_CSS || mathJaxFormat==MATHJAX_FORMAT_t::NativeMML)
-      {
-        Config_updateEnum(MATHJAX_FORMAT,MATHJAX_FORMAT_t::chtml);
-      }
+      case MATHJAX_VERSION_t::MathJax_2:
+        if (mathJaxFormat==MATHJAX_FORMAT_t::chtml)
+        {
+          Config_updateEnum(MATHJAX_FORMAT,MATHJAX_FORMAT_t::HTML_CSS);
+        }
+        break;
+      case MATHJAX_VERSION_t::MathJax_3:
+        if (mathJaxFormat==MATHJAX_FORMAT_t::HTML_CSS || mathJaxFormat==MATHJAX_FORMAT_t::NativeMML)
+        {
+          Config_updateEnum(MATHJAX_FORMAT,MATHJAX_FORMAT_t::chtml);
+        }
+        break;
+      case MATHJAX_VERSION_t::MathJax_4:
+        if (mathJaxFormat==MATHJAX_FORMAT_t::HTML_CSS || mathJaxFormat==MATHJAX_FORMAT_t::NativeMML)
+        {
+          Config_updateEnum(MATHJAX_FORMAT,MATHJAX_FORMAT_t::chtml);
+        }
+        break;
     }
 
     QCString mathJaxCodefile = Config_getString(MATHJAX_CODEFILE);
@@ -1872,6 +1879,7 @@ void Config::checkAndCorrect(bool quiet, const bool check)
       {
         case MATHJAX_VERSION_t::MathJax_2: path += "2"; break;
         case MATHJAX_VERSION_t::MathJax_3: path += "3"; break;
+        case MATHJAX_VERSION_t::MathJax_4: path += "4"; break;
       }
     }
 

src/htmlgen.cpp

@@ -464,6 +464,69 @@ static QCString substituteHtmlKeywords(const QCString &file,
 
     switch (mathJaxVersion)
     {
+      case MATHJAX_VERSION_t::MathJax_4:
+        {
+          mathJaxJs += "<script type=\"text/javascript\">\n"
+                       "window.MathJax = {\n"
+                       "  options: {\n"
+                       "    ignoreHtmlClass: 'tex2jax_ignore',\n"
+                       "    processHtmlClass: 'tex2jax_process'\n"
+                       "  }";
+         // MACRO / EXT
+         const StringVector &mathJaxExtensions = Config_getList(MATHJAX_EXTENSIONS);
+         if (!mathJaxExtensions.empty() || !g_latex_macro.isEmpty())
+         {
+           mathJaxJs+= ",\n";
+           if (!mathJaxExtensions.empty())
+           {
+             bool first = true;
+             mathJaxJs+= "  loader: {\n"
+                         "    load: [";
+             for (const auto &s : mathJaxExtensions)
+             {
+               if (!first) mathJaxJs+= ",";
+               mathJaxJs+= "'[tex]/"+QCString(s.c_str())+"'";
+               first = false;
+             }
+             mathJaxJs+= "]\n"
+                         "  },\n";
+           }
+           mathJaxJs+= "  tex: {\n"
+                       "    macros: {";
+           if (!g_latex_macro.isEmpty())
+           {
+             mathJaxJs += g_latex_macro+"    ";
+           }
+           mathJaxJs+="},\n"
+                       "    packages: {\n";
+           bool first = true;
+           for (const auto &s : mathJaxExtensions)
+           {
+             if (!first) mathJaxJs+= ",";
+             mathJaxJs+= "\n";
+             mathJaxJs+= "        '[+]': ['"+QCString(s.c_str())+"']";
+             first = false;
+           }
+           mathJaxJs += "\n    }\n";
+           mathJaxJs += "  }\n";
+         }
+         else
+         {
+           mathJaxJs += "\n";
+         }
+         mathJaxJs += "};\n";
+         // MATHJAX_CODEFILE
+         if (!g_mathjax_code.isEmpty())
+         {
+           mathJaxJs += g_mathjax_code;
+           mathJaxJs += "\n";
+         }
+         mathJaxJs+="</script>\n";
+         mathJaxJs += "<script type=\"text/javascript\" id=\"MathJax-script\" async=\"async\" src=\"" +
+                      path + "tex-" + mathJaxFormat.lower() + ".js\">";
+         mathJaxJs+="</script>\n";
+        }
+        break;
       case MATHJAX_VERSION_t::MathJax_3:
         {
           mathJaxJs += // "<script src=\"https://polyfill.io/v3/polyfill.min.js?features=es6\"></script>\n" // needed for IE11 only, see #10354