backend/libinput: send touch frame events

backend/libinput/events.c

@@ -271,7 +271,7 @@ void handle_libinput_event(struct wlr_libinput_backend *backend,
 		handle_touch_cancel(event, libinput_dev);
 		break;
 	case LIBINPUT_EVENT_TOUCH_FRAME:
-		// no-op (at least for now)
+		handle_touch_frame(event, libinput_dev);
 		break;
 	case LIBINPUT_EVENT_TABLET_TOOL_AXIS:
 		handle_tablet_tool_axis(event, libinput_dev);

backend/libinput/touch.c

@@ -95,3 +95,14 @@ void handle_touch_cancel(struct libinput_event *event,
 	wlr_event.touch_id = libinput_event_touch_get_seat_slot(tevent);
 	wlr_signal_emit_safe(&wlr_dev->touch->events.cancel, &wlr_event);
 }
+
+void handle_touch_frame(struct libinput_event *event,
+		struct libinput_device *libinput_dev) {
+	struct wlr_input_device *wlr_dev =
+		get_appropriate_device(WLR_INPUT_DEVICE_TOUCH, libinput_dev);
+	if (!wlr_dev) {
+		wlr_log(WLR_DEBUG, "Got a touch event for a device with no touch?");
+		return;
+	}
+	wlr_signal_emit_safe(&wlr_dev->touch->events.frame, NULL);
+}

include/backend/libinput.h

@@ -82,6 +82,8 @@ void handle_touch_motion(struct libinput_event *event,
 		struct libinput_device *device);
 void handle_touch_cancel(struct libinput_event *event,
 		struct libinput_device *device);
+void handle_touch_frame(struct libinput_event *event,
+		struct libinput_device *device);
 
 struct wlr_tablet *create_libinput_tablet(
 		struct libinput_device *device);