input/cursor: pass gesture events to clients

Some wayland clients (mostly GTK3 apps) like eog or evince support
gestures like pinch-to-zoom. These gestures are given to clients
via the pointer_gestures_v1 protocol. This is already supported in
wlroots, so we just need to hook up the events here in sway.

Fixes swaywm#4724

include/sway/input/cursor.h

@@ -3,6 +3,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <wlr/types/wlr_pointer_constraints_v1.h>
+#include <wlr/types/wlr_pointer_gestures_v1.h>
 #include <wlr/types/wlr_surface.h>
 #include "sway/input/seat.h"
 
@@ -32,6 +33,11 @@ struct sway_cursor {
 	struct wlr_pointer_constraint_v1 *active_constraint;
 	pixman_region32_t confine; // invalid if active_constraint == NULL
 
+	struct wlr_pointer_gestures_v1 *pointer_gestures;
+	struct wl_listener pinch_begin;
+	struct wl_listener pinch_update;
+	struct wl_listener pinch_end;
+
 	struct wl_listener motion;
 	struct wl_listener motion_absolute;
 	struct wl_listener button;

sway/input/cursor.c

@@ -735,6 +735,34 @@ static void handle_request_set_cursor(struct wl_listener *listener,
 			event->hotspot_y, focused_client);
 }
 
+static void handle_pointer_pinch_begin(struct wl_listener *listener, void *data) {
+	struct sway_cursor *cursor = wl_container_of(
+			listener, cursor, pinch_begin);
+	struct wlr_event_pointer_pinch_begin *event = data;
+	wlr_pointer_gestures_v1_send_pinch_begin(
+			cursor->pointer_gestures, cursor->seat->wlr_seat,
+			event->time_msec, event->fingers);
+}
+
+static void handle_pointer_pinch_update(struct wl_listener *listener, void *data) {
+	struct sway_cursor *cursor = wl_container_of(
+			listener, cursor, pinch_update);
+	struct wlr_event_pointer_pinch_update *event = data;
+	wlr_pointer_gestures_v1_send_pinch_update(
+			cursor->pointer_gestures, cursor->seat->wlr_seat,
+			event->time_msec, event->dx, event->dy,
+			event->scale, event->rotation);
+}
+
+static void handle_pointer_pinch_end(struct wl_listener *listener, void *data) {
+	struct sway_cursor *cursor = wl_container_of(
+			listener, cursor, pinch_end);
+	struct wlr_event_pointer_pinch_end *event = data;
+	wlr_pointer_gestures_v1_send_pinch_end(
+			cursor->pointer_gestures, cursor->seat->wlr_seat,
+			event->time_msec, event->cancelled);
+}
+
 void cursor_set_image(struct sway_cursor *cursor, const char *image,
 		struct wl_client *client) {
 	if (!(cursor->seat->wlr_seat->capabilities & WL_SEAT_CAPABILITY_POINTER)) {
@@ -825,6 +853,15 @@ struct sway_cursor *sway_cursor_create(struct sway_seat *seat) {
 	cursor->hide_source = wl_event_loop_add_timer(server.wl_event_loop,
 			hide_notify, cursor);
 
+	cursor->pointer_gestures = wlr_pointer_gestures_v1_create(server.wl_display);
+
+	cursor->pinch_begin.notify = handle_pointer_pinch_begin;
+	wl_signal_add(&wlr_cursor->events.pinch_begin, &cursor->pinch_begin);
+	cursor->pinch_update.notify = handle_pointer_pinch_update;
+	wl_signal_add(&wlr_cursor->events.pinch_update, &cursor->pinch_update);
+	cursor->pinch_end.notify = handle_pointer_pinch_end;
+	wl_signal_add(&wlr_cursor->events.pinch_end, &cursor->pinch_end);
+
 	// input events
 	wl_signal_add(&wlr_cursor->events.motion, &cursor->motion);
 	cursor->motion.notify = handle_cursor_motion_relative;