desktop-shell: Invalidate saved position when output is destroyed

If the saved position for a fullscreen or maximized output view is in an
output that has been unplugged, the coordinates don't make sense
anymore. In that case, invalidate them and use the initial position
algorithm when changing them back to the basic state.

Signed-off-by: Zhang, Xiong Y <xiong.y.zhang@intel.com>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>

src/compositor.c

@@ -409,6 +409,9 @@ weston_view_output_destroy_handler(struct wl_listener *listener,
 	}
 
 	weston_view_set_position(ev, x, y);
+
+	if (ev->surface->output_destroyed)
+		ev->surface->output_destroyed(ev->surface);
 }
 
 WL_EXPORT struct weston_view *

src/compositor.h

@@ -885,6 +885,12 @@ struct weston_surface {
 	void (*configure)(struct weston_surface *es, int32_t sx, int32_t sy);
 	void *configure_private;
 
+	/* If non-NULL, this function will be called on surface->output::
+	 * destroy, after the output is removed from the compositor's
+	 * output list and the remaining outputs moved.
+	 */
+	void (*output_destroyed)(struct weston_surface *surface);
+
 	/* Parent's list of its sub-surfaces, weston_subsurface:parent_link.
 	 * Contains also the parent itself as a dummy weston_subsurface,
 	 * if the list is not empty.