relative_pointer: implement protocol events

Implement zwp_relative_pointer_v1.relative_motion event, along with some
glue code in wlr_seat_pointer and rootston.

include/wlr/types/wlr_relative_pointer_v1.h

@@ -66,4 +66,8 @@ struct wlr_relative_pointer_v1 {
 struct wlr_relative_pointer_manager_v1 *wlr_relative_pointer_v1_create(struct wl_display *display);
 void wlr_relative_pointer_v1_destroy(struct wlr_relative_pointer_manager_v1 *relative_pointer_manager);
 
+void wlr_relative_pointer_v1_send_relative_motion(struct wl_resource *resource,
+	uint64_t time, double dx, double dy, double dx_unaccel, double
+	dy_unaccel);
+
 #endif

include/wlr/types/wlr_seat.h

@@ -314,6 +314,18 @@ void wlr_seat_pointer_clear_focus(struct wlr_seat *wlr_seat);
 void wlr_seat_pointer_send_motion(struct wlr_seat *wlr_seat, uint32_t time,
 		double sx, double sy);
 
+/** Send relative motion events to the surface with pointer focus. Coordinates
+ * for the motion event are relative to current pointer location, both
+ * accelerated and unaccelerated. Compositors should use
+ * `wlr_seat_pointer_notify_relative_motion()` to send relative motion events
+ * to respect relative pointer requests by clients.
+ *
+ * Note that the timestamp is 64 bit, split into high 32 bits and low 32 bits.
+ */
+void wlr_seat_pointer_notify_relative_motion(struct wlr_seat *wlr_seat,
+		uint64_t time, double dx, double dy, double dx_unaccel,
+		double dy_unaccel);
+
 /**
  * Send a button event to the surface with pointer focus. Coordinates for the
  * button event are surface-local. Returns the serial. Compositors should use

rootston/cursor.c

@@ -310,6 +310,9 @@ void roots_cursor_handle_motion(struct roots_cursor *cursor,
 	double dx = event->delta_x;
 	double dy = event->delta_y;
 
+	wlr_seat_pointer_notify_relative_motion(cursor->seat->seat, (uint64_t)
+		event->time_msec, dx, dy, dx, dy);
+
 	if (cursor->active_constraint) {
 		struct roots_view *view = cursor->pointer_view->view;
 		assert(view);
@@ -349,6 +352,11 @@ void roots_cursor_handle_motion_absolute(struct roots_cursor *cursor,
 	wlr_cursor_absolute_to_layout_coords(cursor->cursor, event->device, event->x,
 		event->y, &lx, &ly);
 
+	double dx = lx - cursor->cursor->x;
+	double dy = ly - cursor->cursor->y;
+	wlr_seat_pointer_notify_relative_motion(cursor->seat->seat, (uint64_t)
+		event->time_msec, dx, dy, dx, dy);
+
 	if (cursor->pointer_view) {
 		struct roots_view *view = cursor->pointer_view->view;
 

types/seat/wlr_seat_pointer.c

@@ -5,6 +5,7 @@
 #include <time.h>
 #include <wayland-server.h>
 #include <wlr/types/wlr_input_device.h>
+#include <wlr/types/wlr_relative_pointer_v1.h>
 #include <wlr/util/log.h>
 #include "types/wlr_seat.h"
 #include "util/signal.h"
@@ -304,6 +305,20 @@ void wlr_seat_pointer_notify_motion(struct wlr_seat *wlr_seat, uint32_t time,
 	grab->interface->motion(grab, time, sx, sy);
 }
 
+void wlr_seat_pointer_notify_relative_motion(struct wlr_seat *wlr_seat,
+	uint64_t time, double dx, double dy, double dx_unaccel, double dy_unaccel) {
+	struct wlr_seat_client *client = wlr_seat->pointer_state.focused_client;
+	if (client == NULL) {
+		return;
+	}
+
+	struct wl_resource *resource;
+	wl_resource_for_each(resource, &client->relative_pointers) {
+		wlr_relative_pointer_v1_send_relative_motion(resource, time, dx, dy,
+			dx_unaccel, dy_unaccel);
+	}
+}
+
 uint32_t wlr_seat_pointer_notify_button(struct wlr_seat *wlr_seat,
 		uint32_t time, uint32_t button, uint32_t state) {
 	clock_gettime(CLOCK_MONOTONIC, &wlr_seat->last_event);

types/wlr_relative_pointer_v1.c

@@ -187,3 +187,16 @@ void wlr_relative_pointer_v1_destroy(struct wlr_relative_pointer_manager_v1 *rel
 
 	wlr_log(WLR_DEBUG, "relative_pointer_v1 manager destroyed");
 }
+
+
+void wlr_relative_pointer_v1_send_relative_motion(struct wl_resource *resource,
+	uint64_t time, double dx, double dy, double dx_unaccel, double
+	dy_unaccel)
+{
+	assert(wl_resource_instance_of(resource, &zwp_relative_pointer_v1_interface,
+		&relative_pointer_v1_impl));
+	zwp_relative_pointer_v1_send_relative_motion(resource,
+		(uint32_t) (time >> 32), (uint32_t) time, wl_fixed_from_double(dx),
+		wl_fixed_from_double(dy), wl_fixed_from_double(dx_unaccel),
+		wl_fixed_from_double(dy_unaccel));
+}