input/tablet: allow moving floating tablet v2 surfaces by pen input

Refs swaywm#5293.

sway/input/seatop_default.c

@@ -194,33 +194,58 @@ static void state_add_button(struct seatop_default_event *e, uint32_t button) {
 	e->pressed_button_count++;
 }
 
-/*----------------------------------\
- * Functions used by handle_button  /
- *--------------------------------*/
+/*-------------------------------------------\
+ * Functions used by handle_tablet_tool_tip  /
+ *----------------------------------------*/
 
 static void handle_tablet_tool_tip(struct sway_seat *seat,
 		struct sway_tablet_tool *tool, uint32_t time_msec,
 		enum wlr_tablet_tool_tip_state state) {
 	if (state == WLR_TABLET_TOOL_TIP_UP) {
 		wlr_tablet_v2_tablet_tool_notify_up(tool->tablet_v2_tool);
 		return;
-	} else if (state == WLR_TABLET_TOOL_TIP_DOWN) {
-		wlr_tablet_v2_tablet_tool_notify_down(tool->tablet_v2_tool);
-		wlr_tablet_tool_v2_start_implicit_grab(tool->tablet_v2_tool);
 	}
 
 	struct sway_cursor *cursor = seat->cursor;
-
 	struct wlr_surface *surface = NULL;
 	double sx, sy;
 	struct sway_node *node = node_at_coords(seat,
 		cursor->cursor->x, cursor->cursor->y, &surface, &sx, &sy);
 
-	if (surface && node && node->type == N_CONTAINER) {
+	if (!sway_assert(surface,
+			"Expected null-surface tablet input to route through pointer emulation")) {
+		return;
+	}
+
+	struct sway_container *cont = node && node->type == N_CONTAINER ?
+		node->sway_container : NULL;
+
+	if (cont) {
+		bool is_floating_or_child = container_is_floating_or_child(cont);
+		bool is_fullscreen_or_child = container_is_fullscreen_or_child(cont);
+		struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->wlr_seat);
+		bool mod_pressed = keyboard &&
+			(wlr_keyboard_get_modifiers(keyboard) & config->floating_mod);
+
+		// Handle beginning floating move
+		if (is_floating_or_child && !is_fullscreen_or_child && mod_pressed) {
+			seat_set_focus_container(seat,
+				seat_get_focus_inactive_view(seat, &cont->node));
+			seatop_begin_move_floating(seat, container_toplevel_ancestor(cont));
+			return;
+		}
+
 		seatop_begin_down(seat, node->sway_container, time_msec, sx, sy);
 	}
+
+	wlr_tablet_v2_tablet_tool_notify_down(tool->tablet_v2_tool);
+	wlr_tablet_tool_v2_start_implicit_grab(tool->tablet_v2_tool);
 }
 
+/*----------------------------------\
+ * Functions used by handle_button  /
+ *--------------------------------*/
+
 static void handle_button(struct sway_seat *seat, uint32_t time_msec,
 		struct wlr_input_device *device, uint32_t button,
 		enum wlr_button_state state) {

sway/input/seatop_move_floating.c

@@ -9,20 +9,31 @@ struct seatop_move_floating_event {
 	double dx, dy; // cursor offset in container
 };
 
+static void finalize_move(struct sway_seat *seat) {
+	struct seatop_move_floating_event *e = seat->seatop_data;
+
+	// We "move" the container to its own location
+	// so it discovers its output again.
+	container_floating_move_to(e->con, e->con->x, e->con->y);
+
+	seatop_begin_default(seat);
+}
+
 static void handle_button(struct sway_seat *seat, uint32_t time_msec,
 		struct wlr_input_device *device, uint32_t button,
 		enum wlr_button_state state) {
 	if (seat->cursor->pressed_button_count == 0) {
-		struct seatop_move_floating_event *e = seat->seatop_data;
-
-		// We "move" the container to its own location
-		// so it discovers its output again.
-		container_floating_move_to(e->con, e->con->x, e->con->y);
-
-		seatop_begin_default(seat);
+		finalize_move(seat);
 	}
 }
 
+static void handle_tablet_tool_tip(struct sway_seat *seat,
+		struct sway_tablet_tool *tool, uint32_t time_msec,
+		enum wlr_tablet_tool_tip_state state) {
+	if (state == WLR_TABLET_TOOL_TIP_UP) {
+		finalize_move(seat);
+	}
+}
 static void handle_pointer_motion(struct sway_seat *seat, uint32_t time_msec,
 		double dx, double dy) {
 	struct seatop_move_floating_event *e = seat->seatop_data;
@@ -42,6 +53,7 @@ static void handle_unref(struct sway_seat *seat, struct sway_container *con) {
 static const struct sway_seatop_impl seatop_impl = {
 	.button = handle_button,
 	.pointer_motion = handle_pointer_motion,
+	.tablet_tool_tip = handle_tablet_tool_tip,
 	.unref = handle_unref,
 };