Decrease the editor FPS cap when the window is unfocused

This decreases CPU/GPU usage when the window is unfocused, which can
be beneficial to laptop users.

This also makes the low-processor mode sleep project setting no longer
affect the editor. Instead, two new editor settings now define the
duration of sleeping when the editor is focused and unfocused.

This closes godotengine#24209 and partially addresses godotengine#29257.

Author: Calinou

editor/editor_node.cpp

@@ -288,6 +288,7 @@ void EditorNode::_notification(int p_what) {
 
 		Engine::get_singleton()->set_editor_hint(true);
 
+		OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/low_processor_mode_sleep_usec")));
 		get_tree()->get_root()->set_usage(Viewport::USAGE_2D_NO_SAMPLING); //reduce memory usage
 		get_tree()->get_root()->set_disable_3d(true);
 		get_tree()->get_root()->set_as_audio_listener(false);
@@ -323,9 +324,18 @@ void EditorNode::_notification(int p_what) {
 
 	if (p_what == MainLoop::NOTIFICATION_WM_FOCUS_IN) {
 
+		// Restore the original FPS cap after focusing back on the editor
+		OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/low_processor_mode_sleep_usec")));
+
 		EditorFileSystem::get_singleton()->scan_changes();
 	}
 
+	if (p_what == MainLoop::NOTIFICATION_WM_FOCUS_OUT) {
+
+		// Set a low FPS cap to decrease CPU/GPU usage while the editor is unfocused
+		OS::get_singleton()->set_low_processor_usage_mode_sleep_usec(int(EDITOR_GET("interface/editor/unfocused_low_processor_mode_sleep_usec")));
+	}
+
 	if (p_what == MainLoop::NOTIFICATION_WM_QUIT_REQUEST) {
 
 		_menu_option_confirm(FILE_QUIT, false);

editor/editor_settings.cpp

@@ -340,6 +340,10 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	hints["interface/editor/dim_amount"] = PropertyInfo(Variant::REAL, "interface/editor/dim_amount", PROPERTY_HINT_RANGE, "0,1,0.01", PROPERTY_USAGE_DEFAULT);
 	_initial_set("interface/editor/dim_transition_time", 0.08f);
 	hints["interface/editor/dim_transition_time"] = PropertyInfo(Variant::REAL, "interface/editor/dim_transition_time", PROPERTY_HINT_RANGE, "0,1,0.001", PROPERTY_USAGE_DEFAULT);
+	_initial_set("interface/editor/low_processor_mode_sleep_usec", 6900); // ~144 FPS
+	hints["interface/editor/low_processor_mode_sleep_usec"] = PropertyInfo(Variant::REAL, "interface/editor/low_processor_mode_sleep_usec", PROPERTY_HINT_RANGE, "1,100000,1", PROPERTY_USAGE_DEFAULT);
+	_initial_set("interface/editor/unfocused_low_processor_mode_sleep_usec", 50000); // 20 FPS
+	hints["interface/editor/unfocused_low_processor_mode_sleep_usec"] = PropertyInfo(Variant::REAL, "interface/editor/unfocused_low_processor_mode_sleep_usec", PROPERTY_HINT_RANGE, "1,100000,1", PROPERTY_USAGE_DEFAULT);
 	_initial_set("interface/editor/separate_distraction_mode", false);
 	_initial_set("interface/editor/save_each_scene_on_quit", true); // Regression
 	_initial_set("interface/editor/quit_confirmation", true);