oxr: Optionally install as the default runtime

CMakeLists.txt

@@ -12,6 +12,7 @@ endif()
 option(OPENXR_USE_LOADER "Application uses loader" ON)
 option(OPENXR_INSTALL_ABSOLUTE_RUNTIME_PATH "Use the absolute path to the runtime in the installed manifest, rather than a bare filename." ON)
 option(VULKAN_ENABLE_VALIDATION "Enable Vulkan validation for Compositor" ON)
+option(INSTALL_ACTIVE_RUNTIME "Make Monado the default OpenXR runtime on install" ON)
 
 ###
 # Dependencies

src/xrt/targets/openxr/CMakeLists.txt

@@ -85,7 +85,10 @@ file(GENERATE
 # by a script we generate now.
 if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
 	set(MANIFEST_RELATIVE_DIR share/openxr/${XR_API_MAJOR}/)
-
+	if(INSTALL_ACTIVE_RUNTIME)
+		configure_file(active_runtime.cmake ${CMAKE_CURRENT_BINARY_DIR}/active_runtime.cmake @ONLY)
+		install(SCRIPT ${CMAKE_CURRENT_BINARY_DIR}/active_runtime.cmake)
+	endif()
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows")
 	# TODO: install target on windows just needs to know where to install manifest
 	set(MANIFEST_RELATIVE_DIR)

src/xrt/targets/openxr/active_runtime.cmake

+# SPDX-License-Identifier: BSL-1.0
+
+include(GNUInstallDirs)
+
+set(MANIFEST_RELATIVE_DIR @MANIFEST_RELATIVE_DIR@)
+set(XR_API_MAJOR @XR_API_MAJOR@)
+set(RUNTIME_TARGET @RUNTIME_TARGET@)
+
+execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink 
+			${CMAKE_INSTALL_PREFIX}/${MANIFEST_RELATIVE_DIR}/${RUNTIME_TARGET}.json
+			${CMAKE_BINARY_DIR}/active_runtime.json)
+file(
+	INSTALL
+	DESTINATION "${CMAKE_INSTALL_FULL_SYSCONFDIR}/xdg/openxr/${XR_API_MAJOR}"
+	TYPE FILE
+	FILES "${CMAKE_BINARY_DIR}/active_runtime.json"
+)