data-device: fix drag icon position

include/rootston/input.h

@@ -75,6 +75,9 @@ struct roots_drag_icon {
 	struct wl_list link; // roots_input::drag_icons
 	bool mapped;
 
+	int32_t sx;
+	int32_t sy;
+
 	struct wl_listener surface_destroy;
 	struct wl_listener surface_commit;
 };

rootston/cursor.c

@@ -313,6 +313,9 @@ static void handle_drag_icon_commit(struct wl_listener *listener, void *data) {
 	// TODO the spec hints at rules that can determine whether the drag icon is
 	// mapped here, but it is not completely clear so we need to test more
 	// toolkits to see how we should interpret the surface state here.
+	drag_icon->sx += drag_icon->surface->current->sx;
+	drag_icon->sy += drag_icon->surface->current->sy;
+
 	drag_icon->mapped = drag_icon->surface->texture->valid;
 }
 

rootston/output.c

@@ -158,10 +158,8 @@ static void output_frame_notify(struct wl_listener *listener, void *data) {
 
 		struct wlr_surface *icon = drag_icon->surface;
 		struct wlr_cursor *cursor = server->input->cursor;
-		// TODO should also use the hotspot to determine the location, but
-		// hotspot is broken right now.
-		double icon_x = cursor->x - icon->current->sx;
-		double icon_y = cursor->y - icon->current->sy;
+		double icon_x = cursor->x + drag_icon->sx;
+		double icon_y = cursor->y + drag_icon->sy;
 		render_surface(icon, desktop, wlr_output, &now, icon_x, icon_y, 0);
 	}