cmake : Add install target to support consuming WIL through cmake. (#137)

* cmake : Use PROJECT_SOURCE_DIR to support FetchContent.

* cmake : Add install target.

* cmake : Add options to disable packaging and unit tests.

* cmake : Typos and cleanup.

CMakeLists.txt

@@ -1,8 +1,12 @@
 cmake_minimum_required(VERSION 3.11)
 project(WIL)
 
+include(GNUInstallDirs)
+
 # Set by build server to speed up build/reduce file/object size
 option(FAST_BUILD "Sets options to speed up build/reduce obj/executable size" OFF)
+option(WIL_BUILD_PACKAGING "Sets option to build the packaging, default on" On)
+option(WIL_BUILD_TESTS "Sets option to build the unit tests, default on" On)
 
 if (NOT DEFINED WIL_BUILD_VERSION)
     set(WIL_BUILD_VERSION "0.0.0")
@@ -17,5 +21,31 @@ else()
     string(REGEX REPLACE "\\\\$" "" WIL_WINDOWS_SDK_VERSION "$ENV{WindowsSDKVersion}")
 endif()
 
-add_subdirectory(packaging)
-add_subdirectory(tests)
+if (${WIL_BUILD_PACKAGING})
+    add_subdirectory(packaging)
+endif()
+
+if (${WIL_BUILD_TESTS})
+    add_subdirectory(tests)
+endif()
+
+# Gather headers into an interface library.
+file(GLOB_RECURSE HEADER_FILES "${PROJECT_SOURCE_DIR}/include/${PROJECT_NAME}/*.h")
+add_library(${PROJECT_NAME} INTERFACE)
+
+# The interface's include directory.
+target_include_directories(${PROJECT_NAME} INTERFACE
+    $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
+    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+)
+
+# Install Package Configuration
+install(TARGETS ${PROJECT_NAME} EXPORT ${PROJECT_NAME}_targets)
+install(EXPORT ${PROJECT_NAME}_targets
+    NAMESPACE ${PROJECT_NAME}::
+    FILE ${PROJECT_NAME}-config.cmake
+    DESTINATION "${CMAKE_INSTALL_DATADIR}/cmake/${PROJECT_NAME}"
+)
+
+# Install the headers at a standard cmake location.
+install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/include/${PROJECT_NAME}" DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")

tests/CMakeLists.txt

@@ -1,8 +1,8 @@
-
-include(${CMAKE_SOURCE_DIR}/cmake/common_build_flags.cmake)
+include(${PROJECT_SOURCE_DIR}/cmake/common_build_flags.cmake)
+cmake_minimum_required(VERSION 3.11)
 
 # All projects need to reference the WIL headers
-include_directories(${CMAKE_SOURCE_DIR}/include)
+include_directories(${PROJECT_SOURCE_DIR}/include)
 
 # TODO: Might be worth trying to conditionally do this on SDK version, assuming there's a semi-easy way to detect that
 include_directories(BEFORE SYSTEM ./workarounds/wrl)