Merge pull request #98 from iliis/cmake_use_as_subdirectory

Allow library to be used with add_subdirectory() in cmake.

CMakeLists.txt

@@ -28,18 +28,18 @@ add_library(QXlsx)
 # Target
 #------------------------------------------------------------------------------
 # Define target sources
-file(GLOB_RECURSE files ${CMAKE_SOURCE_DIR}/QXlsx/source/*.cpp ${CMAKE_SOURCE_DIR}/QXlsx/header/*.h)
+file(GLOB_RECURSE files ${PROJECT_SOURCE_DIR}/QXlsx/source/*.cpp ${PROJECT_SOURCE_DIR}/QXlsx/header/*.h)
 
 target_sources(QXlsx PRIVATE
   ${files}
 )
 
 target_link_libraries(QXlsx PUBLIC Qt5::Core Qt5::Gui Qt5::GuiPrivate)
-target_include_directories(QXlsx PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/QXlsx/header)
+target_include_directories(QXlsx PUBLIC ${PROJECT_SOURCE_DIR}/QXlsx/header)
 
 configure_file(
-  ${CMAKE_SOURCE_DIR}/CMake/QXlsxConfig.cmake.in
-  "${CMAKE_BINARY_DIR}/QXlsxConfig.cmake" @ONLY)
+  ${PROJECT_SOURCE_DIR}/CMake/QXlsxConfig.cmake.in
+  "${PROJECT_BINARY_DIR}/QXlsxConfig.cmake" @ONLY)
 
 export(TARGETS QXlsx
-  FILE "${CMAKE_BINARY_DIR}/QXlsxTargets.cmake")
+  FILE "${PROJECT_BINARY_DIR}/QXlsxTargets.cmake")