wayland/subsurface: Drop unapplied subsurface state on unmap

To prevent it from getting spuriously applied if a wl_subsurface is
later created again for the same wl_surface.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3364>

src/wayland/meta-wayland-subsurface.c

@@ -397,11 +397,38 @@ wl_subsurface_place_below (struct wl_client   *client,
                     META_WAYLAND_SUBSURFACE_PLACEMENT_BELOW);
 }
 
+void
+meta_wayland_subsurface_drop_placement_ops (MetaWaylandSurfaceState *state,
+                                            MetaWaylandSurface      *surface)
+{
+  GSList **list = &state->subsurface_placement_ops;
+  GSList *link = *list;
+
+  while (link)
+    {
+      MetaWaylandSubsurfacePlacementOp *op = link->data;
+
+      if (op->surface == surface)
+        {
+          g_free (link->data);
+          *list = g_slist_delete_link (*list, link);
+        }
+      else
+        {
+          list = &link->next;
+        }
+
+      link = *list;
+    }
+}
+
 static void
 permanently_unmap_subsurface (MetaWaylandSurface *surface)
 {
   MetaWaylandSubsurfacePlacementOp *op;
   MetaWaylandTransaction *transaction;
+  MetaWaylandSurface *parent;
+  MetaWaylandSurfaceState *pending_state;
 
   op = get_subsurface_placement_op (surface, NULL,
                                     META_WAYLAND_SUBSURFACE_PLACEMENT_BELOW);
@@ -412,6 +439,24 @@ permanently_unmap_subsurface (MetaWaylandSurface *surface)
   meta_wayland_transaction_add_subsurface_position (transaction, surface, 0, 0);
   meta_wayland_transaction_commit (transaction);
 
+  if (surface->sub.transaction)
+    meta_wayland_transaction_drop_subsurface_state (surface->sub.transaction,
+                                                    surface);
+
+  parent = surface->protocol_state.parent;
+  pending_state = meta_wayland_surface_get_pending_state (parent);
+  if (pending_state && pending_state->subsurface_placement_ops)
+    meta_wayland_subsurface_drop_placement_ops (pending_state, surface);
+
+  while (parent)
+    {
+      if (parent->sub.transaction)
+        meta_wayland_transaction_drop_subsurface_state (parent->sub.transaction,
+                                                        surface);
+
+      parent = parent->protocol_state.parent;
+    }
+
   surface->protocol_state.parent = NULL;
 }
 

src/wayland/meta-wayland-subsurface.h

@@ -44,6 +44,9 @@ void meta_wayland_subsurface_union_geometry (MetaWaylandSubsurface *subsurface,
                                              int                    parent_y,
                                              MtkRectangle          *out_geometry);
 
+void meta_wayland_subsurface_drop_placement_ops (MetaWaylandSurfaceState *state,
+                                                 MetaWaylandSurface      *surface);
+
 void meta_wayland_subsurface_parent_destroyed (MetaWaylandSurface *surface);
 
 void meta_wayland_subsurfaces_init (MetaWaylandCompositor *compositor);

src/wayland/meta-wayland-transaction.c

@@ -101,6 +101,25 @@ meta_wayland_transaction_apply_subsurface_position (MetaWaylandSurface
   surface->sub.y = entry->y;
 }
 
+void
+meta_wayland_transaction_drop_subsurface_state (MetaWaylandTransaction *transaction,
+                                                MetaWaylandSurface     *surface)
+{
+  MetaWaylandSurface *parent = surface->protocol_state.parent;
+  MetaWaylandTransactionEntry *entry;
+
+  entry = meta_wayland_transaction_get_entry (transaction, surface);
+  if (entry)
+    entry->has_sub_pos = FALSE;
+
+  if (!parent)
+    return;
+
+  entry = meta_wayland_transaction_get_entry (transaction, parent);
+  if (entry && entry->state && entry->state->subsurface_placement_ops)
+    meta_wayland_subsurface_drop_placement_ops (entry->state, surface);
+}
+
 static gboolean
 is_ancestor (MetaWaylandSurface *candidate,
              MetaWaylandSurface *reference)

src/wayland/meta-wayland-transaction.h

@@ -20,6 +20,9 @@
 #include "wayland/meta-wayland-types.h"
 #include "wayland/meta-wayland-subsurface.h"
 
+void meta_wayland_transaction_drop_subsurface_state (MetaWaylandTransaction *transaction,
+                                                     MetaWaylandSurface     *surface);
+
 void meta_wayland_transaction_commit (MetaWaylandTransaction *transaction);
 
 MetaWaylandTransactionEntry *meta_wayland_transaction_ensure_entry (MetaWaylandTransaction *transaction,