even more changes

Signed-off-by: Paulchen-Panther <Paulchen--Panter@gmx.net>

dependencies/CMakeLists.txt

@@ -9,6 +9,48 @@ if(ENABLE_WS281XPWM)
 		external/rpi_ws281x/rpihw.c)
 endif()
 
+set(USE_SYSTEM_FLATBUFFERS_LIBS ${DEFAULT_USE_SYSTEM_FLATBUFFERS_LIBS} CACHE BOOL "use flatbuffers library from system")
+
+if (USE_SYSTEM_FLATBUFFERS_LIBS)
+	find_package(flatbuffers REQUIRED)
+	include_directories(${FLATBUFFERS_INCLUDE_DIRS})
+else ()
+	set(BUILD_SHARED_LIBS OFF CACHE BOOL "Build shared flatbuffers library")
+	set(FLATBUFFERS_BUILD_TESTS OFF CACHE BOOL "Build Flatbuffers with tests")
+	add_subdirectory(external/flatbuffers)
+
+	if(CMAKE_CROSSCOMPILING)
+		# when crosscompiling import the flatc executable targets from a file generated by a native build
+		option(IMPORT_FLATC "flatc export file (flatc_export.cmake) from a native build" "IMPORT_FLATC-FILE_NOT_FOUND")
+		include(${IMPORT_FLATC})
+	else()
+		# export the flatc compiler so it can be used when cross compiling
+		export(TARGETS flatc FILE "${CMAKE_BINARY_DIR}/flatc_export.cmake")
+	endif()
+
+	# define the include for the flatbuffers library at the parent scope
+	set(FLATBUFFERS_INCLUDE_DIRS "${CMAKE_CURRENT_SOURCE_DIR}/external/flatbuffers/include")
+	set(FLATBUFFERS_INCLUDE_DIRS ${FLATBUFFERS_INCLUDE_DIRS} PARENT_SCOPE)
+
+	# define the flatc executable at the parent scope
+	get_property(FLATBUFFERS_FLATC_EXECUTABLE TARGET flatc PROPERTY LOCATION)
+	set(FLATBUFFERS_FLATC_EXECUTABLE ${FLATBUFFERS_FLATC_EXECUTABLE} PARENT_SCOPE)
+endif()
+
+message(STATUS "Using flatbuffers compiler: " ${FLATBUFFERS_FLATC_EXECUTABLE})
+
+
+function(compile_flattbuffer_schema SRC_FBS OUTPUT_DIR)
+  string(REGEX REPLACE "\\.fbs$" "_generated.h" GEN_HEADER ${SRC_FBS})
+  add_custom_command(
+    OUTPUT ${GEN_HEADER}
+    COMMAND "${FLATBUFFERS_FLATC_EXECUTABLE}" -c --no-includes --gen-mutable
+			--gen-object-api
+			-o "${OUTPUT_DIR}"
+			"${SRC_FBS}"
+    DEPENDS flatc)
+endfunction()
+
 set(USE_SYSTEM_PROTO_LIBS ${DEFAULT_USE_SYSTEM_PROTO_LIBS} CACHE BOOL "use protobuf library from system")
 
 if (USE_SYSTEM_PROTO_LIBS)