cmake: Add FindObs helper for external plugin use

This is meant to be copied and used by external plugin projects for the
sake of finding and depending on OBS.

cmake/external/FindObs.cmake

@@ -0,0 +1,105 @@
+# This module can be copied and used by external plugins for OBS
+#
+# Once done these will be defined:
+#
+#  LIBOBS_FOUND
+#  LIBOBS_INCLUDE_DIRS
+#  LIBOBS_LIBRARIES
+#
+# For use in OBS:
+#
+#  OBS_INCLUDE_DIR
+
+find_package(PkgConfig QUIET)
+if (PKG_CONFIG_FOUND)
+	pkg_check_modules(_OBS QUIET obs)
+endif()
+
+if(CMAKE_SIZEOF_VOID_P EQUAL 8)
+	set(_lib_suffix 64)
+else()
+	set(_lib_suffix 32)
+endif()
+
+if(DEFINED CMAKE_BUILD_TYPE)
+	if(CMAKE_BUILD_TYPE STREQUAL "Debug")
+		set(_build_type_base "debug")
+	else()
+		set(_build_type_base "release")
+	endif()
+endif()
+
+find_path(OBS_INCLUDE_DIR
+	NAMES obs.h
+	HINTS
+		ENV obsPath${_lib_suffix}
+		ENV obsPath
+		${obsPath}
+	PATHS
+		/usr/include /usr/local/include /opt/local/include /sw/include
+	PATH_SUFFIXES
+		libobs
+	)
+
+function(find_obs_lib base_name repo_build_path lib_name)
+	string(TOUPPER "${base_name}" base_name_u)
+
+	if(DEFINED _build_type_base)
+		set(_build_type_${repo_build_path} "${_build_type_base}/${repo_build_path}")
+		set(_build_type_${repo_build_path}${_lib_suffix} "${_build_type_base}${_lib_suffix}/${repo_build_path}")
+	endif()
+
+	find_library(${base_name_u}_LIB
+		NAMES ${_${base_name_u}_LIBRARIES} ${lib_name} lib${lib_name}
+		HINTS
+			ENV obsPath${_lib_suffix}
+			ENV obsPath
+			${obsPath}
+			${_${base_name_u}_LIBRARY_DIRS}
+		PATHS
+			/usr/lib /usr/local/lib /opt/local/lib /sw/lib
+		PATH_SUFFIXES
+			lib${_lib_suffix} lib
+			libs${_lib_suffix} libs
+			bin${_lib_suffix} bin
+			../lib${_lib_suffix} ../lib
+			../libs${_lib_suffix} ../libs
+			../bin${_lib_suffix} ../bin
+			# base repo non-msvc-specific search paths
+			${_build_type_${repo_build_path}}
+			${_build_type_${repo_build_path}${_lib_suffix}}
+			build/${repo_build_path}
+			build${_lib_suffix}/${repo_build_path}
+			# base repo msvc-specific search paths on windows
+			build${_lib_suffix}/${repo_build_path}/Debug
+			build${_lib_suffix}/${repo_build_path}/RelWithDebInfo
+			build/${repo_build_path}/Debug
+			build/${repo_build_path}/RelWithDebInfo
+		)
+endfunction()
+
+find_obs_lib(OBS libobs obs)
+
+if(MSVC)
+	find_obs_lib(W32_PTHREADS deps/w32-pthreads w32-pthreads)
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Libobs DEFAULT_MSG OBS_LIB OBS_INCLUDE_DIR)
+mark_as_advanced(OBS_INCLUDE_DIR OBS_LIB)
+
+if(LIBOBS_FOUND)
+	if(MSVC)
+		if (NOT DEFINED W32_PTHREADS_LIB)
+			message(FATAL_ERROR "Could not find the w32-pthreads library" )
+		endif()
+
+		set(W32_PTHREADS_INCLUDE_DIR ${OBS_INCLUDE_DIR}/../deps/w32-pthreads)
+	endif()
+
+	set(LIBOBS_INCLUDE_DIRS ${OBS_INCLUDE_DIR} ${W32_PTHREADS_INCLUDE_DIR})
+	set(LIBOBS_LIBRARIES ${OBS_LIB} ${W32_PTHREADS_LIB})
+	include(${OBS_INCLUDE_DIR}/../cmake/external/ObsPluginHelpers.cmake)
+else()
+	message(FATAL_ERROR "Could not find the libobs library" )
+endif()