wayland: Replace manual GNode subsurface iteration with macro

Similar to wl_list_foreach(), add
META_WAYLAND_SURFACE_FOREACH_SUBSURFACE() that iterates over all the
subsurfaces of a surface, without the caller needing to care about
implementation details, such as leaf nodes vs non-leaf nodes.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/961

src/wayland/meta-wayland-actor-surface.c

@@ -147,9 +147,9 @@ meta_wayland_actor_surface_real_sync_actor_state (MetaWaylandActorSurface *actor
     meta_wayland_surface_role_get_surface (surface_role);
   MetaSurfaceActor *surface_actor;
   MetaShapedTexture *stex;
-  GNode *n;
   cairo_rectangle_int_t surface_rect;
   int geometry_scale;
+  MetaWaylandSurface *subsurface_surface;
 
   surface_actor = priv->actor;
   stex = meta_surface_actor_get_texture (surface_actor);
@@ -213,19 +213,12 @@ meta_wayland_actor_surface_real_sync_actor_state (MetaWaylandActorSurface *actor
       meta_surface_actor_reset_viewport_dst_size (surface_actor);
     }
 
-  for (n = g_node_first_child (surface->subsurface_branch_node);
+  META_WAYLAND_SURFACE_FOREACH_SUBSURFACE (surface, subsurface_surface)
-       n;
-       n = g_node_next_sibling (n))
     {
-      MetaWaylandSurface *subsurface_surface = n->data;
+      MetaWaylandActorSurface *actor_surface;
-      MetaWaylandActorSurface *subsurface_actor_surface;
 
-      if (G_NODE_IS_LEAF (n))
+      actor_surface = META_WAYLAND_ACTOR_SURFACE (subsurface_surface->role);
-        continue;
+      meta_wayland_actor_surface_sync_actor_state (actor_surface);
-
-      subsurface_actor_surface =
-        META_WAYLAND_ACTOR_SURFACE (subsurface_surface->role);
-      meta_wayland_actor_surface_sync_actor_state (subsurface_actor_surface);
     }
 }
 

src/wayland/meta-wayland-pointer.c

@@ -1205,20 +1205,13 @@ static gboolean
 pointer_can_grab_surface (MetaWaylandPointer *pointer,
                           MetaWaylandSurface *surface)
 {
-  GNode *n;
+  MetaWaylandSurface *subsurface;
 
   if (pointer->focus_surface == surface)
     return TRUE;
 
-  for (n = g_node_first_child (surface->subsurface_branch_node);
+  META_WAYLAND_SURFACE_FOREACH_SUBSURFACE (surface, subsurface)
-       n;
-       n = g_node_next_sibling (n))
     {
-      MetaWaylandSurface *subsurface = n->data;
-
-      if (G_NODE_IS_LEAF (n))
-        continue;
-
       if (pointer_can_grab_surface (pointer, subsurface))
         return TRUE;
     }

src/wayland/meta-wayland-shell-surface.c

@@ -43,23 +43,17 @@ meta_wayland_shell_surface_calculate_geometry (MetaWaylandShellSurface *shell_su
   MetaWaylandSurface *surface =
     meta_wayland_surface_role_get_surface (surface_role);
   MetaRectangle geometry;
-  GNode *n;
+  MetaWaylandSurface *subsurface_surface;
 
   geometry = (MetaRectangle) {
     .width = meta_wayland_surface_get_width (surface),
     .height = meta_wayland_surface_get_height (surface),
   };
 
-  for (n = g_node_first_child (surface->subsurface_branch_node);
+  META_WAYLAND_SURFACE_FOREACH_SUBSURFACE (surface, subsurface_surface)
-       n;
-       n = g_node_next_sibling (n))
     {
-      MetaWaylandSurface *subsurface_surface = n->data;
       MetaWaylandSubsurface *subsurface;
 
-      if (G_NODE_IS_LEAF (n))
-        continue;
-
       subsurface = META_WAYLAND_SUBSURFACE (subsurface_surface->role);
       meta_wayland_subsurface_union_geometry (subsurface,
                                               0, 0,

src/wayland/meta-wayland-subsurface.c

@@ -204,7 +204,7 @@ meta_wayland_subsurface_union_geometry (MetaWaylandSubsurface *subsurface,
   MetaWaylandSurface *surface =
     meta_wayland_surface_role_get_surface (surface_role);
   MetaRectangle geometry;
-  GNode *n;
+  MetaWaylandSurface *subsurface_surface;
 
   geometry = (MetaRectangle) {
     .x = surface->offset_x + surface->sub.x,
@@ -215,16 +215,10 @@ meta_wayland_subsurface_union_geometry (MetaWaylandSubsurface *subsurface,
 
   meta_rectangle_union (out_geometry, &geometry, out_geometry);
 
-  for (n = g_node_first_child (surface->subsurface_branch_node);
+  META_WAYLAND_SURFACE_FOREACH_SUBSURFACE (surface, subsurface_surface)
-       n;
-       n = g_node_next_sibling (n))
     {
-      MetaWaylandSurface *subsurface_surface = n->data;
       MetaWaylandSubsurface *subsurface;
 
-      if (G_NODE_IS_LEAF (n))
-        continue;
-
       subsurface = META_WAYLAND_SUBSURFACE (subsurface_surface->role);
       meta_wayland_subsurface_union_geometry (subsurface,
                                               parent_x + geometry.x,

src/wayland/meta-wayland-surface.c

@@ -600,20 +600,6 @@ meta_wayland_surface_state_class_init (MetaWaylandSurfaceStateClass *klass)
                   G_TYPE_NONE, 0);
 }
 
-static void
-parent_surface_state_applied (GNode    *subsurface_node,
-                              gpointer  user_data)
-{
-  MetaWaylandSurface *surface = subsurface_node->data;
-  MetaWaylandSubsurface *subsurface;
-
-  if (G_NODE_IS_LEAF (subsurface_node))
-    return;
-
-  subsurface = META_WAYLAND_SUBSURFACE (surface->role);
-  meta_wayland_subsurface_parent_state_applied (subsurface);
-}
-
 void
 meta_wayland_surface_cache_pending_frame_callbacks (MetaWaylandSurface      *surface,
                                                     MetaWaylandSurfaceState *pending)
@@ -627,6 +613,7 @@ static void
 meta_wayland_surface_apply_state (MetaWaylandSurface      *surface,
                                   MetaWaylandSurfaceState *state)
 {
+  MetaWaylandSurface *subsurface_surface;
   gboolean had_damage = FALSE;
 
   g_signal_emit (surface, surface_signals[SURFACE_PRE_STATE_APPLIED], 0);
@@ -802,10 +789,13 @@ cleanup:
 
   meta_wayland_surface_state_reset (state);
 
-  g_node_children_foreach (surface->subsurface_branch_node,
+  META_WAYLAND_SURFACE_FOREACH_SUBSURFACE (surface, subsurface_surface)
-                           G_TRAVERSE_ALL,
+    {
-                           parent_surface_state_applied,
+      MetaWaylandSubsurface *subsurface;
-                           NULL);
+
+      subsurface = META_WAYLAND_SUBSURFACE (subsurface_surface->role);
+      meta_wayland_subsurface_parent_state_applied (subsurface);
+    }
 
   if (had_damage)
     {
@@ -1287,22 +1277,14 @@ meta_wayland_surface_update_outputs (MetaWaylandSurface *surface)
 static void
 meta_wayland_surface_update_outputs_recursively (MetaWaylandSurface *surface)
 {
-  GNode *n;
+  MetaWaylandSurface *subsurface_surface;
 
   meta_wayland_surface_update_outputs (surface);
 
-  for (n = g_node_first_child (surface->subsurface_branch_node);
+  META_WAYLAND_SURFACE_FOREACH_SUBSURFACE (surface, subsurface_surface)
-       n;
+    meta_wayland_surface_update_outputs_recursively (subsurface_surface);
-       n = g_node_next_sibling (n))
-    {
-      if (G_NODE_IS_LEAF (n))
-        continue;
-
-      meta_wayland_surface_update_outputs_recursively (n->data);
-    }
 }
 
-
 void
 meta_wayland_surface_set_window (MetaWaylandSurface *surface,
                                  MetaWindow         *window)

src/wayland/meta-wayland-surface.h

@@ -328,4 +328,38 @@ void                meta_wayland_surface_notify_geometry_changed (MetaWaylandSur
 int                 meta_wayland_surface_get_width (MetaWaylandSurface *surface);
 int                 meta_wayland_surface_get_height (MetaWaylandSurface *surface);
 
+static inline GNode *
+meta_get_next_subsurface_sibling (GNode *n)
+{
+  GNode *next;
+
+  if (!n)
+    return NULL;
+
+  next = g_node_next_sibling (n);
+  if (!next)
+    return NULL;
+  if (!G_NODE_IS_LEAF (next))
+    return next;
+  else
+    return meta_get_next_subsurface_sibling (next);
+}
+
+static inline GNode *
+meta_get_first_subsurface_node (MetaWaylandSurface *surface)
+{
+  GNode *n;
+
+  n = g_node_first_child (surface->subsurface_branch_node);
+  if (!G_NODE_IS_LEAF (n))
+    return n;
+  else
+    return meta_get_next_subsurface_sibling (n);
+}
+
+#define META_WAYLAND_SURFACE_FOREACH_SUBSURFACE(surface, subsurface) \
+  for (GNode *G_PASTE(__n, __LINE__) = meta_get_first_subsurface_node ((surface)); \
+       (subsurface = (G_PASTE (__n, __LINE__) ? G_PASTE (__n, __LINE__)->data : NULL)); \
+       G_PASTE (__n, __LINE__) = meta_get_next_subsurface_sibling (G_PASTE (__n, __LINE__)))
+
 #endif

src/wayland/meta-wayland-tablet-tool.c

@@ -989,20 +989,13 @@ static gboolean
 tablet_tool_can_grab_surface (MetaWaylandTabletTool *tool,
                               MetaWaylandSurface    *surface)
 {
-  GNode *n;
+  MetaWaylandSurface *subsurface;
 
   if (tool->focus_surface == surface)
     return TRUE;
 
-  for (n = g_node_first_child (surface->subsurface_branch_node);
+  META_WAYLAND_SURFACE_FOREACH_SUBSURFACE (surface, subsurface)
-       n;
-       n = g_node_next_sibling (n))
     {
-      MetaWaylandSurface *subsurface = n->data;
-
-      if (G_NODE_IS_LEAF (n))
-        continue;
-
       if (tablet_tool_can_grab_surface (tool, subsurface))
         return TRUE;
     }