5 files changed, 115 insertions, 7 deletions

diff --git a/include/wlr/types/wlr_data_device.h b/include/wlr/types/wlr_data_device.h
index b21e53bc..189ab59b 100644
--- a/include/wlr/types/wlr_data_device.h
+++ b/include/wlr/types/wlr_data_device.h
@@ -71,6 +71,7 @@ struct wlr_drag {
 	bool cancelling;
 	int32_t grab_touch_id;
 
+	struct wl_listener point_destroy;
 	struct wl_listener icon_destroy;
 	struct wl_listener source_destroy;
 	struct wl_listener seat_client_unbound;
diff --git a/include/wlr/types/wlr_seat.h b/include/wlr/types/wlr_seat.h
index e05bea47..ee13f99d 100644
--- a/include/wlr/types/wlr_seat.h
+++ b/include/wlr/types/wlr_seat.h
@@ -28,9 +28,13 @@ struct wlr_touch_point {
 	int32_t touch_id;
 	struct wlr_surface *surface;
 	struct wlr_seat_client *client;
+
+	struct wlr_surface *focus_surface;
+	struct wlr_seat_client *focus_client;
 	double sx, sy;
 
 	struct wl_listener surface_destroy;
+	struct wl_listener focus_surface_destroy;
 	struct wl_listener resource_destroy;
 
 	struct {
@@ -74,6 +78,8 @@ struct wlr_touch_grab_interface {
 			struct wlr_touch_point *point);
 	void (*motion)(struct wlr_seat_touch_grab *grab, uint32_t time,
 			struct wlr_touch_point *point);
+	void (*enter)(struct wlr_seat_touch_grab *grab, uint32_t time,
+			struct wlr_touch_point *point);
 	// XXX this will conflict with the actual touch cancel which is different so
 	// we need to rename this
 	void (*cancel)(struct wlr_seat_touch_grab *grab);
@@ -423,11 +429,25 @@ void wlr_seat_touch_notify_up(struct wlr_seat *seat, uint32_t time,
  * even if the surface is not the owner of the touch point for processing by
  * grabs.
  */
-void wlr_seat_touch_notify_motion(struct wlr_seat *seat,
+void wlr_seat_touch_notify_motion(struct wlr_seat *seat, uint32_t time,
+		int32_t touch_id, double sx, double sy);
+
+/**
+ * Notify the seat that the touch point given by `touch_id` has entered a new
+ * surface. The surface is required. To clear focus, use
+ * `wlr_seat_touch_point_clear_focus()`.
+ */
+void wlr_seat_touch_point_focus(struct wlr_seat *seat,
 		struct wlr_surface *surface, uint32_t time, int32_t touch_id, double sx,
 		double sy);
 
 /**
+ * Clear the focused surface for the touch point given by `touch_id`.
+ */
+void wlr_seat_touch_point_clear_focus(struct wlr_seat *seat, uint32_t time,
+		int32_t touch_id);
+
+/**
  * Send a touch down event to the client of the given surface. All future touch
  * events for this point will go to this surface. If the touch down is valid,
  * this will add a new touch point with the given `touch_id`. The touch down may
diff --git a/rootston/cursor.c b/rootston/cursor.c
index eff81104..16441f4b 100644
--- a/rootston/cursor.c
+++ b/rootston/cursor.c
@@ -262,8 +262,13 @@ void roots_cursor_handle_touch_motion(struct roots_cursor *cursor,
 	view_at(desktop, lx, ly, &surface, &sx, &sy);
 
 	if (surface) {
-		wlr_seat_touch_notify_motion(cursor->seat->seat, surface, event->time_msec,
+		wlr_seat_touch_point_focus(cursor->seat->seat, surface,
+			event->time_msec, event->slot, sx, sy);
+		wlr_seat_touch_notify_motion(cursor->seat->seat, event->time_msec,
 			event->slot, sx, sy);
+	} else {
+		wlr_seat_touch_point_clear_focus(cursor->seat->seat, event->time_msec,
+			event->slot);
 	}
 }
 
diff --git a/types/wlr_data_device.c b/types/wlr_data_device.c
index 462320e0..57122818 100644
--- a/types/wlr_data_device.c
+++ b/types/wlr_data_device.c
@@ -554,6 +554,12 @@ static void touch_drag_motion(struct wlr_seat_touch_grab *grab, uint32_t time,
 	}
 }
 
+static void touch_drag_enter(struct wlr_seat_touch_grab *grab, uint32_t time,
+		struct wlr_touch_point *point) {
+	struct wlr_drag *drag = grab->data;
+	wlr_drag_set_focus(drag, point->focus_surface, point->sx, point->sy);
+}
+
 static void touch_drag_cancel(struct wlr_seat_touch_grab *grab) {
 	struct wlr_drag *drag = grab->data;
 	wlr_drag_end(drag);
@@ -563,6 +569,7 @@ const struct wlr_touch_grab_interface wlr_data_device_touch_drag_interface = {
 	.down = touch_drag_down,
 	.up = touch_drag_up,
 	.motion = touch_drag_motion,
+	.enter = touch_drag_enter,
 	.cancel = touch_drag_cancel,
 };
 
diff --git a/types/wlr_seat.c b/types/wlr_seat.c
index 80b9a7c3..eb73b174 100644
--- a/types/wlr_seat.c
+++ b/types/wlr_seat.c
@@ -313,8 +313,15 @@ static void default_touch_up(struct wlr_seat_touch_grab *grab, uint32_t time,
 
 static void default_touch_motion(struct wlr_seat_touch_grab *grab,
 		uint32_t time, struct wlr_touch_point *point) {
-	wlr_seat_touch_send_motion(grab->seat, time, point->touch_id, point->sx,
-		point->sy);
+	if (!point->focus_surface || point->focus_surface == point->surface) {
+		wlr_seat_touch_send_motion(grab->seat, time, point->touch_id, point->sx,
+			point->sy);
+	}
+}
+
+static void default_touch_enter(struct wlr_seat_touch_grab *grab,
+		uint32_t time, struct wlr_touch_point *point) {
+	// not handled by default
 }
 
 static void default_touch_cancel(struct wlr_seat_touch_grab *grab) {
@@ -325,6 +332,7 @@ static const struct wlr_touch_grab_interface default_touch_grab_impl = {
 	.down = default_touch_down,
 	.up = default_touch_up,
 	.motion = default_touch_motion,
+	.enter = default_touch_enter,
 	.cancel = default_touch_cancel,
 };
 
@@ -998,9 +1006,8 @@ void wlr_seat_touch_notify_up(struct wlr_seat *seat, uint32_t time,
 	touch_point_destroy(point);
 }
 
-void wlr_seat_touch_notify_motion(struct wlr_seat *seat,
-		struct wlr_surface *surface, uint32_t time, int32_t touch_id, double sx,
-		double sy) {
+void wlr_seat_touch_notify_motion(struct wlr_seat *seat, uint32_t time,
+		int32_t touch_id, double sx, double sy) {
 	clock_gettime(CLOCK_MONOTONIC, &seat->last_event);
 	struct wlr_seat_touch_grab *grab = seat->touch_state.grab;
 	struct wlr_touch_point *point = wlr_seat_touch_get_point(seat, touch_id);
@@ -1015,6 +1022,74 @@ void wlr_seat_touch_notify_motion(struct wlr_seat *seat,
 	grab->interface->motion(grab, time, point);
 }
 
+static void touch_point_clear_focus(struct wlr_touch_point *point) {
+	if (point->focus_surface) {
+		wl_list_remove(&point->focus_surface_destroy.link);
+		point->focus_client = NULL;
+		point->focus_surface = NULL;
+	}
+}
+
+static void handle_point_focus_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_touch_point *point =
+		wl_container_of(listener, point, focus_surface_destroy);
+	touch_point_clear_focus(point);
+}
+
+static void touch_point_set_focus(struct wlr_touch_point *point,
+		struct wlr_surface *surface, double sx, double sy) {
+	if (point->focus_surface == surface) {
+		return;
+	}
+
+	touch_point_clear_focus(point);
+
+	if (surface && surface->resource) {
+		struct wlr_seat_client *client =
+			wlr_seat_client_for_wl_client(point->client->seat,
+				wl_resource_get_client(surface->resource));
+
+		if (client && client->touch) {
+			wl_signal_add(&surface->events.destroy, &point->focus_surface_destroy);
+			point->focus_surface_destroy.notify = handle_point_focus_destroy;
+			point->focus_surface = surface;
+			point->focus_client = client;
+			point->sx = sx;
+			point->sy = sy;
+		}
+	}
+}
+
+void wlr_seat_touch_point_focus(struct wlr_seat *seat,
+		struct wlr_surface *surface, uint32_t time, int32_t touch_id, double sx,
+		double sy) {
+	assert(surface);
+	struct wlr_touch_point *point = wlr_seat_touch_get_point(seat, touch_id);
+	if (!point) {
+		wlr_log(L_ERROR, "got touch point focus for unknown touch point");
+		return;
+	}
+	struct wlr_surface *focus = point->focus_surface;
+	touch_point_set_focus(point, surface, sx, sy);
+
+	if (focus != point->focus_surface) {
+		struct wlr_seat_touch_grab *grab = seat->touch_state.grab;
+		grab->interface->enter(grab, time, point);
+	}
+}
+
+void wlr_seat_touch_point_clear_focus(struct wlr_seat *seat, uint32_t time,
+		int32_t touch_id) {
+	struct wlr_touch_point *point = wlr_seat_touch_get_point(seat, touch_id);
+	if (!point) {
+		wlr_log(L_ERROR, "got touch point focus for unknown touch point");
+		return;
+	}
+
+	touch_point_set_focus(point, NULL, 0, 0);
+}
+
 void wlr_seat_touch_send_down(struct wlr_seat *seat,
 		struct wlr_surface *surface, uint32_t time, int32_t touch_id, double sx,
 		double sy) {