Fix pointer events with multiple outputs in wayland backend

backend/wayland/backend.c

@@ -1,6 +1,7 @@
 #include <stdlib.h>
 #include <stdint.h>
 #include <assert.h>
+#include <limits.h>
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 #include <wayland-server.h>
@@ -117,6 +118,38 @@ struct wlr_wl_backend_output *wlr_wl_output_for_surface(
 	return NULL;
 }
 
+void wlr_wl_output_layout_get_box(struct wlr_wl_backend *backend,
+		struct wlr_box *box) {
+	int min_x = INT_MAX, min_y = INT_MAX;
+	int max_x = INT_MIN, max_y = INT_MIN;
+
+	struct wlr_wl_backend_output *output;
+	wl_list_for_each(output, &backend->outputs, link) {
+		struct wlr_output *wlr_output = &output->wlr_output;
+
+		int width, height;
+		wlr_output_effective_resolution(wlr_output, &width, &height);
+
+		if (wlr_output->lx < min_x) {
+			min_x = wlr_output->lx;
+		}
+		if (wlr_output->ly < min_y) {
+			min_y = wlr_output->ly;
+		}
+		if (wlr_output->lx + width > max_x) {
+			max_x = wlr_output->lx + width;
+		}
+		if (wlr_output->ly + height > max_y) {
+			max_y = wlr_output->ly + height;
+		}
+	}
+
+	box->x = min_x;
+	box->y = min_y;
+	box->width = max_x - min_x;
+	box->height = max_y - min_y;
+}
+
 struct wlr_backend *wlr_wl_backend_create(struct wl_display *display) {
 	wlr_log(L_INFO, "Creating wayland backend");
 

backend/wayland/wl_seat.c

@@ -52,23 +52,28 @@ static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
 		return;
 	}
 
+	struct wlr_output *wlr_output = &wlr_wl_pointer->current_output->wlr_output;
+
 	struct wlr_box box;
 	wl_egl_window_get_attached_size(wlr_wl_pointer->current_output->egl_window,
 		&box.width, &box.height);
 	box.x = wl_fixed_to_int(surface_x);
 	box.y = wl_fixed_to_int(surface_y);
 	struct wlr_box transformed;
-	wlr_output_transform_apply_to_box(
+	wlr_output_transform_apply_to_box(wlr_output->transform, &box, &transformed);
-		wlr_wl_pointer->current_output->wlr_output.transform, &box,
+	box.x /= wlr_output->scale;
-		&transformed);
+	box.y /= wlr_output->scale;
+
+	struct wlr_box layout_box;
+	wlr_wl_output_layout_get_box(wlr_wl_pointer->current_output->backend, &layout_box);
 
 	struct wlr_event_pointer_motion_absolute wlr_event;
 	wlr_event.device = dev;
 	wlr_event.time_msec = time;
-	wlr_event.width_mm = transformed.width;
+	wlr_event.width_mm = layout_box.width;
-	wlr_event.height_mm = transformed.height;
+	wlr_event.height_mm = layout_box.height;
-	wlr_event.x_mm = transformed.x;
+	wlr_event.x_mm = transformed.x + wlr_output->lx + layout_box.x;
-	wlr_event.y_mm = transformed.y;
+	wlr_event.y_mm = transformed.y + wlr_output->ly + layout_box.y;
 	wl_signal_emit(&dev->pointer->events.motion_absolute, &wlr_event);
 }
 

include/backend/wayland.h

@@ -7,6 +7,7 @@
 #include <wayland-egl.h>
 #include <wlr/render/egl.h>
 #include <wlr/backend/wayland.h>
+#include <wlr/types/wlr_box.h>
 #include <wlr/types/wlr_output.h>
 #include <wlr/types/wlr_input_device.h>
 #include <wayland-util.h>
@@ -75,6 +76,8 @@ void wlr_wl_registry_poll(struct wlr_wl_backend *backend);
 void wlr_wl_output_update_cursor(struct wlr_wl_backend_output *output);
 struct wlr_wl_backend_output *wlr_wl_output_for_surface(
 		struct wlr_wl_backend *backend, struct wl_surface *surface);
+void wlr_wl_output_layout_get_box(struct wlr_wl_backend *backend,
+		struct wlr_box *box);
 
 extern const struct wl_seat_listener seat_listener;