Add new building option ENABLE_EXTERNAL_MATHJAX, set to ON by default.

If set to ON, it generates HTML documentation using MathJax from an external CDN when doing 'make doc'. If set to OFF, MathJax is still looked for in the system and used if found, so it can be used offline. If not found, it is not used.

CMakeLists.txt

@@ -117,6 +117,8 @@ if(CMAKE_VERSION VERSION_LESS 3.5.1)
     set(ENABLE_BENCHMARKS OFF)
 endif()
 
+option(ENABLE_EXTERNAL_MATHJAX "Use MathJax from an external CDN in HTML docs" ON)
+
 
 ################################################################################
 # GNSS-SDR version information
@@ -330,6 +332,7 @@ set(GNSSSDR_MATIO_LOCAL_VERSION "1.5.18")
 set(GNSSSDR_PUGIXML_LOCAL_VERSION "1.10")
 set(GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION "3.13.0")
 set(GNSSSDR_BENCHMARK_LOCAL_VERSION "1.5.2")
+set(GNSSSDR_MATHJAX_EXTERNAL_VERSION "2.7.7")
 
 if(CMAKE_VERSION VERSION_LESS "3.0.2")
     set(GNSSSDR_GFLAGS_LOCAL_VERSION "2.2.1")  # Fix for CentOS 7
@@ -2533,7 +2536,7 @@ endif()
 
 
 ################################################################################
-# Doxygen - http://www.doxygen.nl (OPTIONAL, used if found)
+# Doxygen - https://www.doxygen.nl (OPTIONAL, used if found)
 ################################################################################
 if(CMAKE_VERSION VERSION_LESS 3.6.9)
     find_package(Doxygen)
@@ -2541,7 +2544,7 @@ else()
     find_package(Doxygen OPTIONAL_COMPONENTS dot)
 endif()
 set_package_properties(Doxygen PROPERTIES
-    URL "http://www.doxygen.nl"
+    URL "https://www.doxygen.nl"
     PURPOSE "Used to generate code documentation by doing '${CMAKE_MAKE_PROGRAM_PRETTY_NAME} doc'"
     TYPE OPTIONAL
 )
@@ -2562,14 +2565,21 @@ endif()
 set_package_properties(LATEX PROPERTIES
     URL "https://www.latex-project.org"
     DESCRIPTION "High-quality typesetting system"
-    PURPOSE "Used to generate a PDF manual by doing '${CMAKE_MAKE_PROGRAM_PRETTY_NAME} pdfmanual'"
+    PURPOSE "Used to generate a PDF manual by doing '${CMAKE_MAKE_PROGRAM_PRETTY_NAME} pdfmanual'."
     TYPE OPTIONAL
 )
+if(DEFINED MATHJAX2_ROOT)
+    set(ENABLE_EXTERNAL_MATHJAX OFF)
+endif()
+if(ENABLE_EXTERNAL_MATHJAX AND NOT DEFINED MATHJAX2_USE_ROOT)
+    set(MATHJAX2_USE_ROOT "https://cdnjs.cloudflare.com/ajax/libs/mathjax/${GNSSSDR_MATHJAX_EXTERNAL_VERSION}")
+endif()
+unset(MATHJAX2_FOUND CACHE)
 find_package(MATHJAX2)
 set_package_properties(MATHJAX2 PROPERTIES
     URL "https://www.mathjax.org"
     DESCRIPTION "Beautiful and accessible math in all browsers"
-    PURPOSE "Used to generate equations in HTML docs."
+    PURPOSE "Used to generate equations in HTML docs when doing '${CMAKE_MAKE_PROGRAM_PRETTY_NAME} doc'."
     TYPE OPTIONAL
 )
 
@@ -2660,7 +2670,7 @@ if(DOXYGEN_FOUND)
 else()
     message(STATUS " Doxygen has not been found in your system.")
     message(STATUS " You can get nice code documentation by using it!")
-    message(STATUS " Get it from http://www.doxygen.nl/download.html")
+    message(STATUS " Get it from https://www.doxygen.nl/download.html")
     if(${CMAKE_SYSTEM_NAME} MATCHES "Linux|kFreeBSD|GNU")
         if(${LINUX_DISTRIBUTION} MATCHES "Fedora" OR ${LINUX_DISTRIBUTION} MATCHES "Red Hat")
             message(STATUS " or simply by doing 'sudo yum install doxygen-latex'.")
@@ -2672,6 +2682,7 @@ else()
         message(STATUS " or simply by doing 'sudo port install doxygen +docs', if you are using Macports,")
         message(STATUS " or 'brew cask install mactex', then restart Terminal and do 'brew install graphviz doxygen', if you use Homebrew.")
     endif()
+    set(ENABLE_EXTERNAL_MATHJAX OFF)
 endif()
 
 
@@ -3188,6 +3199,7 @@ add_feature_info(ENABLE_OWN_GPSTK ENABLE_OWN_GPSTK "Forces the downloading and b
 add_feature_info(ENABLE_GNSS_SIM_INSTALL ENABLE_GNSS_SIM_INSTALL "Enables downloading and building of gnss-sim.")
 add_feature_info(ENABLE_INSTALL_TESTS ENABLE_INSTALL_TESTS "Install test binaries when doing '${CMAKE_MAKE_PROGRAM_PRETTY_NAME} install'.")
 add_feature_info(ENABLE_BENCHMARKS ENABLE_BENCHMARKS "Enables building of code snippet benchmarks.")
+add_feature_info(ENABLE_EXTERNAL_MATHJAX ENABLE_EXTERNAL_MATHJAX "Use MathJax from an external CDN in HTML docs when doing '${CMAKE_MAKE_PROGRAM_PRETTY_NAME} doc'.")
 
 message(STATUS "")
 message(STATUS "***************************************")

cmake/Modules/FindMATHJAX2.cmake

@@ -28,15 +28,6 @@
 #  - MATHJAX2_PATH      - Path to the MathJax root directory
 
 
-if(CMAKE_VERSION VERSION_LESS 3.11)
-    if(__INCLUDED_MATHJAX2)
-        return()
-    endif()
-    set(__INCLUDED_MATHJAX2 TRUE)
-else()
-    include_guard()
-endif()
-
 if(DEFINED MATHJAX2_USE_ROOT)
     set(MATHJAX2_FOUND TRUE)
     set(MATHJAX2_PATH "${MATHJAX2_USE_ROOT}/")

docs/doxygen/other/main_page.dox

@@ -157,7 +157,7 @@ You can create the documentation by doing:
 $ make doc
 \endverbatim
 
-from the <tt>gnss-sdr/build</tt> folder. In both cases, <a href="http://www.doxygen.nl/" target="_blank">Doxygen</a> will generate HTML documentation that can be
+from the <tt>gnss-sdr/build</tt> folder. In both cases, <a href="https://www.doxygen.nl/" target="_blank">Doxygen</a> will generate HTML documentation that can be
 retrieved pointing your browser of preference to <tt>gnss-sdr/docs/html/index.html</tt>.
 
 There are two more extra targets available. From the <tt>gnss-sdr/build</tt> folder: