wlr-seat: touch grab begin and end

include/wlr/types/wlr_seat.h

@@ -175,6 +175,9 @@ struct wlr_seat {
 		struct wl_signal keyboard_grab_begin;
 		struct wl_signal keyboard_grab_end;
 
+		struct wl_signal touch_grab_begin;
+		struct wl_signal touch_grab_end;
+
 		struct wl_signal request_set_cursor;
 
 		struct wl_signal selection;
@@ -371,6 +374,19 @@ void wlr_seat_keyboard_enter(struct wlr_seat *wlr_seat,
  */
 void wlr_seat_keyboard_clear_focus(struct wlr_seat *wlr_seat);
 
+/**
+ * Start a grab of the touch device of this seat. The grabber is responsible for
+ * handling all touch events until the grab ends.
+ */
+void wlr_seat_touch_start_grab(struct wlr_seat *wlr_seat,
+		struct wlr_seat_touch_grab *grab);
+
+/**
+ * End the grab of the touch device of this seat. This reverts the grab back to
+ * the default grab for the touch device.
+ */
+void wlr_seat_touch_end_grab(struct wlr_seat *wlr_seat);
+
 /**
  * Get the active touch point with the given `touch_id`. If the touch point does
  * not exist or is no longer active, returns NULL.

types/wlr_seat.c

@@ -407,6 +407,9 @@ struct wlr_seat *wlr_seat_create(struct wl_display *display, const char *name) {
 	wl_signal_init(&wlr_seat->events.keyboard_grab_begin);
 	wl_signal_init(&wlr_seat->events.keyboard_grab_end);
 
+	wl_signal_init(&wlr_seat->events.touch_grab_begin);
+	wl_signal_init(&wlr_seat->events.touch_grab_end);
+
 	return wlr_seat;
 }
 
@@ -867,6 +870,26 @@ void wlr_seat_keyboard_notify_key(struct wlr_seat *seat, uint32_t time,
 	grab->interface->key(grab, time, key, state);
 }
 
+void wlr_seat_touch_start_grab(struct wlr_seat *wlr_seat,
+		struct wlr_seat_touch_grab *grab) {
+	grab->seat = wlr_seat;
+	wlr_seat->touch_state.grab = grab;
+
+	wl_signal_emit(&wlr_seat->events.touch_grab_begin, grab);
+}
+
+void wlr_seat_touch_end_grab(struct wlr_seat *wlr_seat) {
+	struct wlr_seat_touch_grab *grab = wlr_seat->touch_state.grab;
+
+	if (grab != wlr_seat->touch_state.default_grab) {
+		wlr_seat->touch_state.grab = wlr_seat->touch_state.default_grab;
+		wl_signal_emit(&wlr_seat->events.touch_grab_end, grab);
+		if (grab->interface->cancel) {
+			grab->interface->cancel(grab);
+		}
+	}
+}
+
 static void touch_point_destroy(struct wlr_touch_point *point) {
 	wl_list_remove(&point->surface_destroy.link);
 	wl_list_remove(&point->resource_destroy.link);