Move cmake code to generate a C++ source file from a binary data file into a helper module

CMakeLists.txt

@@ -1,6 +1,7 @@
 project(updater)
 
 cmake_minimum_required(VERSION 2.6)
+set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/modules")
 
 include_directories(external)
 include_directories(external/TinyThread/source)

cmake/modules/GenerateCppResourceFile.cmake

@@ -0,0 +1,21 @@
+
+# Convert a binary data file into a C++
+# source file for embedding into an application binary
+#
+# Currently only implemented for Unix.  Requires the 'xxd'
+# tool to be installed.
+#
+# INPUT_FILE : The name of the binary data file to be converted into a C++
+#              source file.
+#
+# CPP_FILE   : The path of the C++ source file to be generated.
+#              See the documentation for xxd for information on
+#              the structure of the generated source file.
+#
+# INPUT_FILE_TARGET : The name of the target which generates INPUT_FILE
+#
+function (generate_cpp_resource_file INPUT_FILE CPP_FILE INPUT_FILE_TARGET)
+	add_custom_command(OUTPUT ${CPP_FILE}
+	                   COMMAND xxd -i ${INPUT_FILE} ${CPP_FILE}
+	                   DEPENDS ${INPUT_FILE_TARGET})
+endfunction()

src/CMakeLists.txt

@@ -2,6 +2,7 @@
 add_subdirectory(tests)
 
 find_package(Threads REQUIRED)
+include(GenerateCppResourceFile)
 
 if (UNIX)
 	add_definitions(-Wall -Werror -Wconversion)
@@ -60,13 +61,11 @@ if (ENABLE_GTK)
 	# embed the GTK helper library into the updater binary.
 	# At runtime it will be extracted and loaded if the
 	# GTK libraries are available
-
 	set(GTK_UPDATER_LIB libupdatergtk.so)
-	set(GTK_BIN_FILE ${CMAKE_CURRENT_BINARY_DIR}/libupdatergtk.cpp)
-	add_custom_command(OUTPUT ${GTK_BIN_FILE}
-	                   COMMAND xxd -i ${GTK_UPDATER_LIB} ${GTK_BIN_FILE}
-	                   DEPENDS updatergtk)
-	set(SOURCES ${SOURCES} UpdateDialogGtkWrapper.cpp ${GTK_BIN_FILE})
+	set(GTK_BIN_CPP_FILE ${CMAKE_CURRENT_BINARY_DIR}/libupdatergtk.cpp)
+	generate_cpp_resource_file(${GTK_UPDATER_LIB} ${GTK_BIN_CPP_FILE} updatergtk)
+
+	set(SOURCES ${SOURCES} UpdateDialogGtkWrapper.cpp ${GTK_BIN_CPP_FILE})
 	set(HEADERS ${HEADERS} UpdateDialogGtkWrapper.h)
 endif()