Add support for building static library (#394)

* Change BUILDING_DLL to BUILDING_SDFORMAT
* Add SDFORMAT_STATIC_DEFINE in cmake
* Drop __GNUC__ conditional

Signed-off-by: Juan Oxoby <juan@vicarious.com>

Co-authored-by: Juan Oxoby <juan@vicarious.com>
Co-authored-by: Anonymous Maarten <madebr@users.noreply.github.com>
Co-authored-by: Louise Poubel <louise@openrobotics.org>
Co-authored-by: Michael Carroll <michael@openrobotics.org>
Co-authored-by: Steve Peters <scpeters@openrobotics.org>

CMakeLists.txt

@@ -146,6 +146,10 @@ else()
   endif()
 endif()
 
+#============================================================================
+# Ask whether we should make a shared or static library.
+option(BUILD_SHARED_LIBS "Set this to true to generate shared libraries (recommended), or false for static libraries" ON)
+
 #####################################
 # Handle CFlags
 unset (CMAKE_C_FLAGS_ALL CACHE)

cmake/SDFUtils.cmake

@@ -52,8 +52,11 @@ endmacro (BUILD_WARNING)
 #################################################
 macro (sdf_add_library _name)
   set(LIBS_DESTINATION ${PROJECT_BINARY_DIR}/src)
-  set_source_files_properties(${ARGN} PROPERTIES COMPILE_DEFINITIONS "BUILDING_DLL")
-  add_library(${_name} SHARED ${ARGN})
+  add_library(${_name} ${ARGN})
+  set_target_properties(${_name} PROPERTIES DEFINE_SYMBOL "BUILDING_SDFORMAT_SHARED")
+  if(NOT BUILD_SHARED_LIBS)
+    target_compile_definitions(${_name} PUBLIC SDFORMAT_STATIC_DEFINE)
+  endif()
   set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBS_DESTINATION})
   if (MSVC)
     set_target_properties( ${_name} PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${LIBS_DESTINATION})

include/sdf/system_util.hh

@@ -26,20 +26,13 @@
  */
 
 #if defined _WIN32 || defined __CYGWIN__
-  #ifdef BUILDING_DLL
-    #ifdef __GNUC__
-      #define SDFORMAT_VISIBLE __attribute__ ((dllexport))
-    #else
-      #define SDFORMAT_VISIBLE __declspec(dllexport)
-    #endif
+  #ifdef BUILDING_SDFORMAT_SHARED
+    #define SDFORMAT_VISIBLE __declspec(dllexport)
+  #elif !defined SDFORMAT_STATIC_DEFINE
+    #define SDFORMAT_VISIBLE __declspec(dllimport)
   #else
-    #ifdef __GNUC__
-      #define SDFORMAT_VISIBLE __attribute__ ((dllimport))
-    #else
-      #define SDFORMAT_VISIBLE __declspec(dllimport)
-    #endif
+    #define SDFORMAT_VISIBLE
   #endif
-  #define SDFORMAT_HIDDEN
 #else
   #if __GNUC__ >= 4 && !defined SDFORMAT_STATIC_DEFINE
     #define SDFORMAT_VISIBLE __attribute__ ((visibility ("default")))