Switch to Doxygen

clang-doc is nice and good, but there are features missing such as the ability to manually create a reference (link)...

api/sixtyfps-cpp/cmake/CMakeLists.txt

@@ -83,20 +83,8 @@ install(FILES
     DESTINATION lib/cmake/SixtyFPS
 )
 
-if(APPLE)
-    execute_process(COMMAND brew --prefix llvm RESULT_VARIABLE prefix_status OUTPUT_VARIABLE llvm_prefix ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
-    if(prefix_status EQUAL "0")
-        set(clang_doc_hint "HINTS;${llvm_prefix}/bin")
-    endif()
+find_package(Doxygen)
+if (DOXYGEN_FOUND)
+    configure_file(Doxyfile.in Doxyfile)
+    add_custom_target(docs ALL COMMAND ${DOXYGEN_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
 endif()
-
-find_program(clang_doc NAMES clang-doc clang-doc-10 ${clang_doc_hint})
-if(clang_doc)
-    message(STATUS "Clang doc found at ${clang_doc}. Will build API documentation")
-    add_library(api_docs lib.cpp)
-    target_link_libraries(api_docs SixtyFPS)
-    add_custom_target(docs ALL COMMAND ${clang_doc} -p ${CMAKE_CURRENT_BINARY_DIR} --format=html --public --project-name "SixtyFPS C++" ${CMAKE_CURRENT_SOURCE_DIR}/lib.cpp)
-else()
-    message(STATUS "Clang doc NOT found. Will NOT build API documentation")
-    add_custom_target(docs COMMAND ${CMAKE} -E echo "Not building documentation because clang-doc wasn't found in PATH")
-endif()