cmake: Support building with Qt5 and Qt6

This allows developers to pick their flavor of Qt, potentially enabling more advanced integrations with Qt in the future. Eventually Qt5 support may be dropped in favor of Qt6.

Fixes #811

CMakeLists.txt

@@ -899,7 +899,7 @@ endfunction()
 function(feature_frontend RESOLVE)
 	is_feature_enabled(FRONTEND T_CHECK)
 	if(RESOLVE AND T_CHECK)
-		if(NOT HAVE_QT)
+		if(NOT (Qt6_FOUND OR Qt5_FOUND))
 			message(WARNING "${LOGPREFIX}Front-End requires Qt. Disabling...")
 			set_feature_disabled(FRONTEND ON)
 		elseif(NOT HAVE_OBS_FRONTEND_API)
@@ -1095,13 +1095,46 @@ if(REQUIRE_NVIDIA_CUDA AND D_PLATFORM_WINDOWS)
 	set(HAVE_NVIDIA_CUDA ON)
 endif()
 
-#- Qt5
+#- Qt
-set(HAVE_QT OFF)
 if(REQUIRE_QT)
-	find_package(Qt5
+	# Try Qt6 first...
-		COMPONENTS Widgets Core REQUIRED
+	find_package(Qt6
+		COMPONENTS Core Gui Widgets
+		CONFIG
+		HINTS
+			"${Qt6_DIR}"
+			"${Qt6_DIR}/lib"
+			"${Qt6_DIR}/lib/cmake"
+			"${Qt6_DIR}/lib/cmake/Qt6"
+			"${QTDIR}"
+			"${QTDIR}/lib"
+			"${QTDIR}/lib/cmake"
+			"${QTDIR}/lib/cmake/Qt6"
+			"${DepsPath}"
+			"${DepsPath}/lib"
+			"${DepsPath}/lib/cmake"
+			"${DepsPath}/lib/cmake/Qt6"
 	)
-	set(HAVE_QT ${Qt5_FOUND})
+	if(NOT Qt6_FOUND)
+		# If Qt6 isn't present, try Qt5
+		find_package(Qt5
+			COMPONENTS Core Gui Widgets
+			CONFIG
+			HINTS
+				"${Qt5_DIR}"
+				"${Qt5_DIR}/lib"
+				"${Qt5_DIR}/lib/cmake"
+				"${Qt5_DIR}/lib/cmake/Qt5"
+				"${QTDIR}"
+				"${QTDIR}/lib"
+				"${QTDIR}/lib/cmake"
+				"${QTDIR}/lib/cmake/Qt5"
+				"${DepsPath}"
+				"${DepsPath}/lib"
+				"${DepsPath}/lib/cmake"
+				"${DepsPath}/lib/cmake/Qt5"
+		)
+	endif()
 endif()
 
 # Verify Requirements
@@ -1303,8 +1336,12 @@ if(REQUIRE_OBS_FRONTEND_API AND HAVE_OBS_FRONTEND_API)
 	list(APPEND PROJECT_LIBRARIES obs-frontend-api)
 endif()
 
-if(REQUIRE_QT AND HAVE_QT)
+if(REQUIRE_QT)
-	list(APPEND PROJECT_LIBRARIES Qt5::Core Qt5::Widgets)
+	if(Qt5_FOUND)
+		list(APPEND PROJECT_LIBRARIES Qt5::Core Qt5::Gui Qt5::Widgets)
+	elseif(Qt6_FOUND)
+		list(APPEND PROJECT_LIBRARIES Qt6::Core Qt6::Gui Qt6::Widgets)
+	endif()
 endif()
 
 ################################################################################
@@ -1949,7 +1986,7 @@ set_source_files_properties(${PROJECT_DATA} ${PROJECT_TEMPLATES} ${PROJECT_UI} P
 )
 
 # Prevent non-UI files from being Qt'd
-if(HAVE_QT)
+if(Qt5_Found OR Qt6_FOUND)
 	set_source_files_properties(${PROJECT_DATA} ${PROJECT_TEMPLATES} ${PROJECT_PRIVATE_GENERATED} ${PROJECT_PRIVATE_SOURCE} PROPERTIES
 		SKIP_AUTOGEN ON
 		SKIP_AUTOMOC ON
@@ -2197,7 +2234,7 @@ if(D_PLATFORM_WINDOWS)
 endif()
 
 # Enable Qt if needed
-if(HAVE_QT)
+if(Qt5_FOUND OR Qt6_FOUND)
 	set_target_properties(${PROJECT_NAME} PROPERTIES
 		AUTOUIC ON
 		AUTOUIC_SEARCH_PATHS "${PROJECT_SOURCE_DIR};${PROJECT_SOURCE_DIR}/ui"
@@ -2254,8 +2291,9 @@ if(D_PLATFORM_MAC)
 		message(STATUS "${LOGPREFIX}Added post-build step for adjusting libobs-frontend-api linking path.")
 	endif()
 
-	# Qt5
+	# Qt
-	if(REQUIRE_QT AND HAVE_QT)
+	if(REQUIRE_QT)
+		if(Qt5_FOUND)
 			# Figure out the linker location for Qt5::Core
 			mac_get_linker_id(TARGET Qt5::Core OUTPUT T_QT5CORE_LINK)
 
@@ -2276,6 +2314,28 @@ if(D_PLATFORM_MAC)
 			message(STATUS "${LOGPREFIX}Added post-build step for adjusting Qt5::Core linking path (Found: ${Qt5_DIR} resolved to ${T_QT5CORE_LINK}).")
 			message(STATUS "${LOGPREFIX}Added post-build step for adjusting Qt5::Gui linking path (Found: ${Qt5_DIR} resolved to ${T_QT5GUI_LINK}).")
 			message(STATUS "${LOGPREFIX}Added post-build step for adjusting Qt5::Widgets linking path (Found: ${Qt5_DIR} resolved to ${T_QT5WIDGETS_LINK}).")
+		elseif(Qt6_FOUND)
+			# Figure out the linker location for Qt6::Core
+			mac_get_linker_id(TARGET Qt6::Core OUTPUT T_QT6CORE_LINK)
+
+			# Figure out the linker location for Qt6::Gui
+			mac_get_linker_id(TARGET Qt6::Gui OUTPUT T_QT6GUI_LINK)
+
+			# Figure out the linker location for Qt6::Widsgets
+			mac_get_linker_id(TARGET Qt6::Widgets OUTPUT T_QT6WIDGETS_LINK)
+
+			add_custom_command(TARGET ${PROJECT_NAME} POST_BUILD
+			# - QtCore
+				COMMAND install_name_tool ARGS -change "${T_QT6CORE_LINK}" "@executable_path/../Frameworks/QtCore.framework/Versions/6/QtCore" $<TARGET_FILE:${PROJECT_NAME}>
+			# - QtGui
+				COMMAND install_name_tool ARGS -change "${T_QT6GUI_LINK}" "@executable_path/../Frameworks/QtGui.framework/Versions/6/QtGui" $<TARGET_FILE:${PROJECT_NAME}>
+			# - QtWidgets
+				COMMAND install_name_tool ARGS -change "${T_QT6WIDGETS_LINK}" "@executable_path/../Frameworks/QtWidgets.framework/Versions/6/QtWidgets" $<TARGET_FILE:${PROJECT_NAME}>
+			)
+			message(STATUS "${LOGPREFIX}Added post-build step for adjusting Qt6::Core linking path (Found: ${Qt6_DIR} resolved to ${T_QT6CORE_LINK}).")
+			message(STATUS "${LOGPREFIX}Added post-build step for adjusting Qt6::Gui linking path (Found: ${Qt6_DIR} resolved to ${T_QT6GUI_LINK}).")
+			message(STATUS "${LOGPREFIX}Added post-build step for adjusting Qt6::Widgets linking path (Found: ${Qt6_DIR} resolved to ${T_QT6WIDGETS_LINK}).")
+		endif()
 	endif()
 endif()