simplify CMakeList with cmake scripts

build/cmake/enable_audio.cmake

@@ -0,0 +1,15 @@
+option(NANA_CMAKE_ENABLE_AUDIO "Enable class audio::play for PCM playback." OFF)
+
+# todo: decide - PUBLIC vs PRIVATE
+if(NANA_CMAKE_ENABLE_AUDIO)
+    target_compile_definitions(nana PUBLIC NANA_ENABLE_AUDIO)
+    if(UNIX)
+        find_package(ASOUND)
+        if(ASOUND_FOUND)
+            target_include_directories(nana PUBLIC ${ASOUND_INCLUDE_DIRS})
+            target_compile_options(nana PUBLIC  -lasound)
+        else()
+            message(FATAL_ERROR "libasound is not found")
+        endif()
+    endif()
+endif()

build/cmake/enable_jpeg.cmake

@@ -0,0 +1,17 @@
+option(NANA_CMAKE_ENABLE_JPEG "Enable the use of JPEG" OFF)
+option(NANA_CMAKE_LIBJPEG_FROM_OS "Use libjpeg from operating system." ON)
+
+# todo: decide - PUBLIC vs PRIVATE
+
+if(NANA_CMAKE_ENABLE_JPEG)
+    if(NANA_CMAKE_LIBJPEG_FROM_OS)
+        find_package(JPEG)
+        if(JPEG_FOUND)
+            target_include_directories(nana PUBLIC  ${JPEG_INCLUDE_DIR})
+            target_compile_options    (nana PUBLIC  ${JPEG_LIBRARY})
+            target_compile_definitions(nana PUBLIC NANA_ENABLE_JPEG USE_LIBJPEG_FROM_OS)
+        endif()
+    else()
+        target_compile_definitions(nana PUBLIC NANA_ENABLE_JPEG)
+    endif()
+endif()

build/cmake/enable_png.cmake

@@ -0,0 +1,17 @@
+option(NANA_CMAKE_ENABLE_PNG "Enable the use of PNG" OFF)
+option(NANA_CMAKE_LIBPNG_FROM_OS "Use libpng from operating system." ON)
+
+# todo: decide - PUBLIC vs PRIVATE
+
+if(NANA_CMAKE_ENABLE_PNG)
+    if(NANA_CMAKE_LIBPNG_FROM_OS)
+        find_package(PNG)
+        if(PNG_FOUND)
+            target_include_directories(nana PUBLIC ${PNG_INCLUDE_DIRS})
+            target_compile_options    (nana PUBLIC ${PNG_LIBRARIES})
+            target_compile_definitions(nana PUBLIC NANA_ENABLE_PNG USE_LIBPNG_FROM_OS)
+        endif()
+    else()
+        target_compile_definitions(nana PUBLIC NANA_ENABLE_PNG)
+    endif()
+endif()

build/cmake/select_filesystem.cmake

@@ -0,0 +1,47 @@
+# The ISO C++ File System Technical Specification (ISO-TS, or STD) is optional.
+#              http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4100.pdf
+# This is not a workaround, but an user option.
+# The library maybe available in the std library in use or from Boost (almost compatible)
+#              http://www.boost.org/doc/libs/1_60_0/libs/filesystem/doc/index.htm
+# or you can choose to use the (partial, but functional) implementation provided by nana.
+# If you include the file <nana/filesystem/filesystem.hpp> or <nana/filesystem/filesystem_ext.hpp>
+# the selected option will be set by nana into std::experimental::filesystem
+# By default Nana will try to use the STD. If STD is not available and NANA_CMAKE_FIND_BOOST_FILESYSTEM
+# is set to ON nana will try to use boost if available. Nana own implementation will be use if none of
+# the previus were selected or available.
+# You can change that default if you change one of the following
+# (please don't define more than one of the _XX_FORCE options):
+option(NANA_CMAKE_FIND_BOOST_FILESYSTEM "Search: Is Boost filesystem available?" OFF)
+option(NANA_CMAKE_NANA_FILESYSTEM_FORCE "Force nana filesystem over ISO and boost?" OFF)
+option(NANA_CMAKE_STD_FILESYSTEM_FORCE "Use of STD filesystem?(a compilation error will ocurre if not available)" OFF)
+option(NANA_CMAKE_BOOST_FILESYSTEM_FORCE "Force use of Boost filesystem if available (over STD)?" OFF)
+
+if(NANA_CMAKE_NANA_FILESYSTEM_FORCE)
+    target_compile_definitions(nana PUBLIC NANA_FILESYSTEM_FORCE)
+
+elseif(NANA_CMAKE_STD_FILESYSTEM_FORCE)
+    target_compile_definitions(nana PUBLIC STD_FILESYSTEM_FORCE)
+    target_compile_options    (nana PUBLIC -lstdc++fs)
+
+elseif(NANA_CMAKE_FIND_BOOST_FILESYSTEM OR NANA_CMAKE_BOOST_FILESYSTEM_FORCE)
+    if(NANA_CMAKE_BOOST_FILESYSTEM_FORCE)
+        target_compile_definitions(nana PUBLIC BOOST_FILESYSTEM_FORCE)
+    else()
+        target_compile_options    (nana PUBLIC -lstdc++fs)
+    endif()
+
+    # https://cmake.org/cmake/help/git-master/module/FindBoost.html
+    # Implicit dependencies such as Boost::filesystem requiring Boost::system will be automatically detected and satisfied,
+    # even if system is not specified when using find_package and if Boost::system is not added to target_link_libraries.
+    # If using Boost::thread, then Thread::Thread will also be added automatically.
+    find_package(Boost COMPONENTS filesystem)
+    if(Boost_FOUND)
+        target_compile_definitions(nana PUBLIC BOOST_FILESYSTEM_AVAILABLE)
+        target_include_directories(nana PUBLIC "${Boost_INCLUDE_DIR}")    # ?? SYSTEM
+        target_link_libraries     (nana PUBLIC ${Boost_LIBRARIES})
+    endif()
+    set(Boost_USE_STATIC_LIBS ON)
+    set(Boost_USE_STATIC_RUNTIME ON)
+endif()
+
+

build/cmake/shared_libs.cmake

@@ -0,0 +1,30 @@
+    if(WIN32)
+        set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
+        if(MSVC)
+            set(DLLTOOL OFF)
+        else()
+            # mingw: If dlltool is found the def and lib file will be created
+            find_program (DLLTOOL dlltool)
+            if(NOT DLLTOOL)
+                message(WARNING "dlltool not found. Skipping import library generation.")
+            endif()
+        endif()
+        if(DLLTOOL)
+            #generate the lib and def files needed by msvc
+            set_target_properties (nana   PROPERTIES
+                    OUTPUT_NAME         nana
+                    ARCHIVE_OUTPUT_NAME nana
+                    LINK_FLAGS "${CMAKE_SHARED_LINKER_FLAGS_INIT} -Wl,--output-def=${CMAKE_CURRENT_BINARY_DIR}/libnana.def"
+                    )
+
+            add_custom_command(TARGET nana POST_BUILD
+                    WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
+                    COMMAND echo "       Generating import library"
+                    COMMAND "${DLLTOOL}" --dllname    "libnana.dll"
+                    --input-def  "libnana.def"
+                    --output-lib "libnana.lib")
+
+            install(FILES "${CMAKE_CURRENT_BINARY_DIR}/libnana.def"
+                    "${CMAKE_CURRENT_BINARY_DIR}/libnana.lib" DESTINATION lib)
+        endif()
+    endif()