ViewLayer: Lazy sync of scene data.

When a change happens which invalidates view layers the syncing will be postponed until the first usage.
This will improve importing or adding many objects in a single operation/script.

`BKE_view_layer_need_resync_tag` is used to tag the view layer to be out of sync. Before accessing
`BKE_view_layer_active_base_get`, `BKE_view_layer_active_object_get`, `BKE_view_layer_active_collection`
or `BKE_view_layer_object_bases` the caller should call `BKE_view_layer_synced_ensure`.

Having two functions ensures that partial syncing could be added as smaller patches in the future. Tagging a
view layer out of sync could be replaced with a partial sync. Eventually the number of full resyncs could be
reduced. After all tagging has been replaced with partial syncs the ensure_sync could be phased out.

This patch has been added to discuss the details and consequences of the current approach. For clarity
the call to BKE_view_layer_ensure_sync is placed close to the getters.
In the future this could be placed in more strategical places to reduce the number of calls or improve
performance. Finding those strategical places isn't that clear. When multiple operations are grouped
in a single script you might want to always check for resync.

Some areas found that can be improved. This list isn't complete.
These areas aren't addressed by this patch as these changes would be hard to detect to the reviewer.
The idea is to add changes to these areas as a separate patch. It might be that the initial commit would reduce
performance compared to master, but will be fixed by the additional patches.

**Object duplication**
During object duplication the syncing is temporarily disabled. With this patch this isn't useful as when disabled
the view_layer is accessed to locate bases. This can be improved by first locating the source bases, then duplicate
and sync and locate the new bases. Will be solved in a separate patch for clarity reasons ({D15886}).

**Object add**
`BKE_object_add` not only adds a new object, but also selects and activates the new base. This requires the
view_layer to be resynced. Some callers reverse the selection and activation (See `get_new_constraint_target`).
We should make the selection and activation optional. This would make it possible to add multiple objects
without having to resync per object.

**Postpone Activate Base**
Setting the basact is done in many locations. They follow a rule as after an action find the base and set
the basact. Finding the base could require a resync. The idea is to store in the view_layer the object which
base will be set in the basact during the next sync, reducing the times resyncing needs to happen.

Reviewed By: mont29

Maniphest Tasks: T73411

Differential Revision: https://developer.blender.org/D15885

11 files changed, 121 insertions, 49 deletions

diff --git a/source/blender/editors/space_outliner/outliner_collections.cc b/source/blender/editors/space_outliner/outliner_collections.cc
index f24d82776ad..48e7aa381ef 100644
--- a/source/blender/editors/space_outliner/outliner_collections.cc
+++ b/source/blender/editors/space_outliner/outliner_collections.cc
@@ -411,7 +411,8 @@ static int collection_hierarchy_delete_exec(bContext *C, wmOperator *op)
   Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
   struct wmMsgBus *mbus = CTX_wm_message_bus(C);
-  const Base *basact_prev = view_layer->basact;
+  BKE_view_layer_synced_ensure(scene, view_layer);
+  const Base *basact_prev = BKE_view_layer_active_base_get(view_layer);
 
   outliner_collection_delete(C, bmain, scene, op->reports, true);
 
@@ -420,7 +421,8 @@ static int collection_hierarchy_delete_exec(bContext *C, wmOperator *op)
 
   WM_main_add_notifier(NC_SCENE | ND_LAYER, nullptr);
 
-  if (basact_prev != view_layer->basact) {
+  BKE_view_layer_synced_ensure(scene, view_layer);
+  if (basact_prev != BKE_view_layer_active_base_get(view_layer)) {
     WM_msg_publish_rna_prop(mbus, &scene->id, view_layer, LayerObjects, active);
   }
 
@@ -960,7 +962,7 @@ static int collection_view_layer_exec(bContext *C, wmOperator *op)
 
   BLI_gset_free(data.collections_to_edit, nullptr);
 
-  BKE_layer_collection_sync(scene, view_layer);
+  BKE_view_layer_need_resync_tag(view_layer);
   DEG_relations_tag_update(bmain);
 
   WM_main_add_notifier(NC_SCENE | ND_LAYER, nullptr);
@@ -1109,7 +1111,7 @@ static int collection_isolate_exec(bContext *C, wmOperator *op)
   }
   BLI_gset_free(data.collections_to_edit, nullptr);
 
-  BKE_layer_collection_sync(scene, view_layer);
+  BKE_view_layer_need_resync_tag(view_layer);
   DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS);
 
   WM_main_add_notifier(NC_SCENE | ND_LAYER_CONTENT, nullptr);
@@ -1193,7 +1195,7 @@ static int collection_visibility_exec(bContext *C, wmOperator *op)
   }
   BLI_gset_free(data.collections_to_edit, nullptr);
 
-  BKE_layer_collection_sync(scene, view_layer);
+  BKE_view_layer_need_resync_tag(view_layer);
   DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS);
 
   WM_main_add_notifier(NC_SCENE | ND_LAYER_CONTENT, nullptr);
@@ -1383,7 +1385,7 @@ static int collection_flag_exec(bContext *C, wmOperator *op)
     BLI_gset_free(data.collections_to_edit, nullptr);
   }
 
-  BKE_layer_collection_sync(scene, view_layer);
+  BKE_view_layer_need_resync_tag(view_layer);
   DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS);
 
   if (!is_render) {
@@ -1492,6 +1494,7 @@ static TreeTraversalAction outliner_hide_collect_data_to_edit(TreeElement *te, v
   }
   else if ((tselem->type == TSE_SOME_ID) && (te->idcode == ID_OB)) {
     Object *ob = (Object *)tselem->id;
+    BKE_view_layer_synced_ensure(data->scene, data->view_layer);
     Base *base = BKE_view_layer_base_find(data->view_layer, ob);
     BLI_gset_add(data->bases_to_edit, base);
   }
@@ -1533,7 +1536,7 @@ static int outliner_hide_exec(bContext *C, wmOperator *UNUSED(op))
   }
   BLI_gset_free(data.bases_to_edit, nullptr);
 
-  BKE_layer_collection_sync(scene, view_layer);
+  BKE_view_layer_need_resync_tag(view_layer);
   DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS);
 
   WM_main_add_notifier(NC_SCENE | ND_LAYER_CONTENT, nullptr);
@@ -1567,11 +1570,12 @@ static int outliner_unhide_all_exec(bContext *C, wmOperator *UNUSED(op))
   }
 
   /* Unhide all objects. */
-  LISTBASE_FOREACH (Base *, base, &view_layer->object_bases) {
+  BKE_view_layer_synced_ensure(scene, view_layer);
+  LISTBASE_FOREACH (Base *, base, BKE_view_layer_object_bases_get(view_layer)) {
     base->flag &= ~BASE_HIDDEN;
   }
 
-  BKE_layer_collection_sync(scene, view_layer);
+  BKE_view_layer_need_resync_tag(view_layer);
   DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS);
 
   WM_main_add_notifier(NC_SCENE | ND_LAYER_CONTENT, nullptr);
diff --git a/source/blender/editors/space_outliner/outliner_dragdrop.cc b/source/blender/editors/space_outliner/outliner_dragdrop.cc
index 4a0e00b8bf1..758928fed8e 100644
--- a/source/blender/editors/space_outliner/outliner_dragdrop.cc
+++ b/source/blender/editors/space_outliner/outliner_dragdrop.cc
@@ -293,6 +293,7 @@ static bool parent_drop_allowed(TreeElement *te, Object *potential_child)
    * active scene and parenting them is allowed (sergey) */
   if (scene) {
     LISTBASE_FOREACH (ViewLayer *, view_layer, &scene->view_layers) {
+      BKE_view_layer_synced_ensure(scene, view_layer);
       if (BKE_view_layer_base_find(view_layer, potential_child)) {
         return true;
       }
@@ -580,6 +581,7 @@ static int scene_drop_invoke(bContext *C, wmOperator *UNUSED(op), const wmEvent
   BKE_collection_object_add(bmain, collection, ob);
 
   LISTBASE_FOREACH (ViewLayer *, view_layer, &scene->view_layers) {
+    BKE_view_layer_synced_ensure(scene, view_layer);
     Base *base = BKE_view_layer_base_find(view_layer, ob);
     if (base) {
       ED_object_base_select(base, BA_SELECT);
diff --git a/source/blender/editors/space_outliner/outliner_draw.cc b/source/blender/editors/space_outliner/outliner_draw.cc
index 4259d3572be..912dc436a95 100644
--- a/source/blender/editors/space_outliner/outliner_draw.cc
+++ b/source/blender/editors/space_outliner/outliner_draw.cc
@@ -284,6 +284,7 @@ static void outliner_object_set_flag_recursive_fn(bContext *C,
         DEG_id_tag_update(&ob_iter->id, ID_RECALC_COPY_ON_WRITE);
       }
       else {
+        BKE_view_layer_synced_ensure(scene, view_layer);
         Base *base_iter = BKE_view_layer_base_find(view_layer, ob_iter);
         /* Child can be in a collection excluded from view-layer. */
         if (base_iter == nullptr) {
@@ -301,7 +302,7 @@ static void outliner_object_set_flag_recursive_fn(bContext *C,
     DEG_relations_tag_update(bmain);
   }
   else {
-    BKE_layer_collection_sync(scene, view_layer);
+    BKE_view_layer_need_resync_tag(view_layer);
     DEG_id_tag_update(&scene->id, ID_RECALC_BASE_FLAGS);
   }
 }
@@ -348,6 +349,7 @@ static void outliner_base_or_object_pointer_create(
     RNA_id_pointer_create(&ob->id, ptr);
   }
   else {
+    BKE_view_layer_synced_ensure(scene, view_layer);
     Base *base = BKE_view_layer_base_find(view_layer, ob);
     RNA_pointer_create(&scene->id, &RNA_ObjectBase, base, ptr);
   }
@@ -1146,6 +1148,7 @@ static void outliner_draw_restrictbuts(uiBlock *block,
         RNA_id_pointer_create(&ob->id, &ptr);
 
         if (space_outliner->show_restrict_flags & SO_RESTRICT_HIDE) {
+          BKE_view_layer_synced_ensure(scene, view_layer);
           Base *base = (te->directdata) ? (Base *)te->directdata :
                                           BKE_view_layer_base_find(view_layer, ob);
           if (base) {
@@ -3213,6 +3216,7 @@ static bool element_should_draw_faded(const TreeViewContext *tvc,
       case ID_OB: {
         const Object *ob = (const Object *)tselem->id;
         /* Lookup in view layer is logically const as it only checks a cache. */
+        BKE_view_layer_synced_ensure(tvc->scene, tvc->view_layer);
         const Base *base = (te->directdata) ? (const Base *)te->directdata :
                                               BKE_view_layer_base_find(
                                                   (ViewLayer *)tvc->view_layer, (Object *)ob);
@@ -3281,6 +3285,7 @@ static void outliner_draw_tree_element(bContext *C,
     if (tselem->type == TSE_SOME_ID) {
       if (te->idcode == ID_OB) {
         Object *ob = (Object *)tselem->id;
+        BKE_view_layer_synced_ensure(tvc->scene, tvc->view_layer);
         Base *base = (te->directdata) ? (Base *)te->directdata :
                                         BKE_view_layer_base_find(tvc->view_layer, ob);
         const bool is_selected = (base != nullptr) && ((base->flag & BASE_SELECTED) != 0);
diff --git a/source/blender/editors/space_outliner/outliner_edit.cc b/source/blender/editors/space_outliner/outliner_edit.cc
index 8618c2999c2..be3c1547579 100644
--- a/source/blender/editors/space_outliner/outliner_edit.cc
+++ b/source/blender/editors/space_outliner/outliner_edit.cc
@@ -1262,10 +1262,12 @@ static int outliner_open_back(TreeElement *te)
 /* Return element representing the active base or bone in the outliner, or NULL if none exists */
 static TreeElement *outliner_show_active_get_element(bContext *C,
                                                      SpaceOutliner *space_outliner,
+                                                     const Scene *scene,
                                                      ViewLayer *view_layer)
 {
   TreeElement *te;
 
+  BKE_view_layer_synced_ensure(scene, view_layer);
   Object *obact = BKE_view_layer_active_object_get(view_layer);
 
   if (!obact) {
@@ -1317,11 +1319,13 @@ static void outliner_show_active(SpaceOutliner *space_outliner,
 static int outliner_show_active_exec(bContext *C, wmOperator *UNUSED(op))
 {
   SpaceOutliner *space_outliner = CTX_wm_space_outliner(C);
+  const Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
   ARegion *region = CTX_wm_region(C);
   View2D *v2d = &region->v2d;
 
-  TreeElement *active_element = outliner_show_active_get_element(C, space_outliner, view_layer);
+  TreeElement *active_element = outliner_show_active_get_element(
+      C, space_outliner, scene, view_layer);
 
   if (active_element) {
     ID *id = TREESTORE(active_element)->id;
diff --git a/source/blender/editors/space_outliner/outliner_select.cc b/source/blender/editors/space_outliner/outliner_select.cc
index ffd3e08fe24..15079448317 100644
--- a/source/blender/editors/space_outliner/outliner_select.cc
+++ b/source/blender/editors/space_outliner/outliner_select.cc
@@ -164,6 +164,7 @@ static void do_outliner_item_mode_toggle_generic(bContext *C, TreeViewContext *t
   ED_undo_group_begin(C);
 
   if (ED_object_mode_set(C, OB_MODE_OBJECT)) {
+    BKE_view_layer_synced_ensure(tvc->scene, tvc->view_layer);
     Base *base_active = BKE_view_layer_base_find(tvc->view_layer, tvc->obact);
     if (base_active != base) {
       BKE_view_layer_base_deselect_all(tvc->scene, tvc->view_layer);
@@ -188,6 +189,7 @@ void outliner_item_mode_toggle(bContext *C,
 
   if ((tselem->type == TSE_SOME_ID) && (te->idcode == ID_OB)) {
     Object *ob = (Object *)tselem->id;
+    BKE_view_layer_synced_ensure(tvc->scene, tvc->view_layer);
     Base *base = BKE_view_layer_base_find(tvc->view_layer, ob);
 
     /* Hidden objects can be removed from the mode. */
@@ -234,11 +236,13 @@ static void tree_element_viewlayer_activate(bContext *C, TreeElement *te)
 /**
  * Select object tree
  */
-static void do_outliner_object_select_recursive(ViewLayer *view_layer,
+static void do_outliner_object_select_recursive(const Scene *scene,
+                                                ViewLayer *view_layer,
                                                 Object *ob_parent,
                                                 bool select)
 {
-  LISTBASE_FOREACH (Base *, base, &view_layer->object_bases) {
+  BKE_view_layer_synced_ensure(scene, view_layer);
+  LISTBASE_FOREACH (Base *, base, BKE_view_layer_object_bases_get(view_layer)) {
     Object *ob = base->object;
     if ((((base->flag & BASE_ENABLED_AND_MAYBE_VISIBLE_IN_VIEWPORT) != 0) &&
          BKE_object_is_child_recursive(ob_parent, ob))) {
@@ -300,6 +304,7 @@ static void tree_element_object_activate(bContext *C,
       ob = (Object *)parent_tselem->id;
 
       /* Don't return when activating children of the previous active object. */
+      BKE_view_layer_synced_ensure(scene, view_layer);
       if (ob == BKE_view_layer_active_object_get(view_layer) && set == OL_SETSEL_NONE) {
         return;
       }
@@ -316,6 +321,7 @@ static void tree_element_object_activate(bContext *C,
   }
 
   /* find associated base in current scene */
+  BKE_view_layer_synced_ensure(sce, view_layer);
   base = BKE_view_layer_base_find(view_layer, ob);
 
   if (scene->toolsettings->object_flag & SCE_OBJECT_MODE_LOCK) {
@@ -371,7 +377,8 @@ static void tree_element_object_activate(bContext *C,
 
     if (recursive) {
       /* Recursive select/deselect for Object hierarchies */
-      do_outliner_object_select_recursive(view_layer, ob, (base->flag & BASE_SELECTED) != 0);
+      do_outliner_object_select_recursive(
+          scene, view_layer, ob, (base->flag & BASE_SELECTED) != 0);
     }
 
     if (set != OL_SETSEL_NONE) {
@@ -382,11 +389,15 @@ static void tree_element_object_activate(bContext *C,
   }
 }
 
-static void tree_element_material_activate(bContext *C, ViewLayer *view_layer, TreeElement *te)
+static void tree_element_material_activate(bContext *C,
+                                           const Scene *scene,
+                                           ViewLayer *view_layer,
+                                           TreeElement *te)
 {
   /* we search for the object parent */
   Object *ob = (Object *)outliner_search_back(te, ID_OB);
   /* Note : ob->matbits can be nullptr when a local object points to a library mesh. */
+  BKE_view_layer_synced_ensure(scene, view_layer);
   if (ob == nullptr || ob != BKE_view_layer_active_object_get(view_layer) ||
       ob->matbits == nullptr) {
     return; /* just paranoia */
@@ -536,6 +547,7 @@ static void tree_element_posechannel_activate(bContext *C,
 }
 
 static void tree_element_bone_activate(bContext *C,
+                                       const Scene *scene,
                                        ViewLayer *view_layer,
                                        TreeElement *te,
                                        TreeStoreElem *tselem,
@@ -546,6 +558,7 @@ static void tree_element_bone_activate(bContext *C,
   Bone *bone = static_cast<Bone *>(te->directdata);
 
   if (!(bone->flag & BONE_HIDDEN_P)) {
+    BKE_view_layer_synced_ensure(scene, view_layer);
     Object *ob = BKE_view_layer_active_object_get(view_layer);
     if (ob) {
       if (set != OL_SETSEL_EXTEND) {
@@ -769,7 +782,7 @@ void tree_element_activate(bContext *C,
       }
       break;
     case ID_MA:
-      tree_element_material_activate(C, tvc->view_layer, te);
+      tree_element_material_activate(C, tvc->scene, tvc->view_layer, te);
       break;
     case ID_WO:
       tree_element_world_activate(C, tvc->scene, te);
@@ -796,7 +809,7 @@ void tree_element_type_active_set(bContext *C,
       tree_element_defgroup_activate(C, te, tselem);
       break;
     case TSE_BONE:
-      tree_element_bone_activate(C, tvc->view_layer, te, tselem, set, recursive);
+      tree_element_bone_activate(C, tvc->scene, tvc->view_layer, te, tselem, set, recursive);
       break;
     case TSE_EBONE:
       tree_element_ebone_activate(C, tvc->scene, tvc->view_layer, te, tselem, set, recursive);
@@ -844,11 +857,13 @@ void tree_element_type_active_set(bContext *C,
   }
 }
 
-static eOLDrawState tree_element_defgroup_state_get(const ViewLayer *view_layer,
+static eOLDrawState tree_element_defgroup_state_get(const Scene *scene,
+                                                    ViewLayer *view_layer,
                                                     const TreeElement *te,
                                                     const TreeStoreElem *tselem)
 {
   const Object *ob = (const Object *)tselem->id;
+  BKE_view_layer_synced_ensure(scene, view_layer);
   if (ob == BKE_view_layer_active_object_get(view_layer)) {
     if (BKE_object_defgroup_active_index_get(ob) == te->index + 1) {
       return OL_DRAWSEL_NORMAL;
@@ -857,12 +872,14 @@ static eOLDrawState tree_element_defgroup_state_get(const ViewLayer *view_layer,
   return OL_DRAWSEL_NONE;
 }
 
-static eOLDrawState tree_element_bone_state_get(const ViewLayer *view_layer,
+static eOLDrawState tree_element_bone_state_get(const Scene *scene,
+                                                ViewLayer *view_layer,
                                                 const TreeElement *te,
                                                 const TreeStoreElem *tselem)
 {
   const bArmature *arm = (const bArmature *)tselem->id;
   const Bone *bone = static_cast<Bone *>(te->directdata);
+  BKE_view_layer_synced_ensure(scene, view_layer);
   const Object *ob = BKE_view_layer_active_object_get(view_layer);
   if (ob && ob->data == arm) {
     if (bone->flag & BONE_SELECTED) {
@@ -896,11 +913,13 @@ static eOLDrawState tree_element_object_state_get(const TreeViewContext *tvc,
   return (tselem->id == (const ID *)tvc->obact) ? OL_DRAWSEL_NORMAL : OL_DRAWSEL_NONE;
 }
 
-static eOLDrawState tree_element_pose_state_get(const ViewLayer *view_layer,
+static eOLDrawState tree_element_pose_state_get(const Scene *scene,
+                                                const ViewLayer *view_layer,
                                                 const TreeStoreElem *tselem)
 {
   const Object *ob = (const Object *)tselem->id;
   /* This will just lookup in a cache, it will not change the arguments. */
+  BKE_view_layer_synced_ensure(scene, (ViewLayer *)view_layer);
   const Base *base = BKE_view_layer_base_find((ViewLayer *)view_layer, (Object *)ob);
   if (base == nullptr) {
     /* Armature not instantiated in current scene (e.g. inside an appended group). */
@@ -942,12 +961,14 @@ static eOLDrawState tree_element_viewlayer_state_get(const bContext *C, const Tr
   return OL_DRAWSEL_NONE;
 }
 
-static eOLDrawState tree_element_posegroup_state_get(const ViewLayer *view_layer,
+static eOLDrawState tree_element_posegroup_state_get(const Scene *scene,
+                                                     ViewLayer *view_layer,
                                                      const TreeElement *te,
                                                      const TreeStoreElem *tselem)
 {
   const Object *ob = (const Object *)tselem->id;
 
+  BKE_view_layer_synced_ensure(scene, view_layer);
   if (ob == BKE_view_layer_active_object_get(view_layer) && ob->pose) {
     if (ob->pose->active_group == te->index + 1) {
       return OL_DRAWSEL_NORMAL;
@@ -1008,12 +1029,14 @@ static eOLDrawState tree_element_layer_collection_state_get(const bContext *C,
   return OL_DRAWSEL_NONE;
 }
 
-static eOLDrawState tree_element_active_material_get(const ViewLayer *view_layer,
+static eOLDrawState tree_element_active_material_get(const Scene *scene,
+                                                     ViewLayer *view_layer,
                                                      const TreeElement *te)
 {
   /* we search for the object parent */
   const Object *ob = (const Object *)outliner_search_back((TreeElement *)te, ID_OB);
   /* Note : ob->matbits can be nullptr when a local object points to a library mesh. */
+  BKE_view_layer_synced_ensure(scene, view_layer);
   if (ob == nullptr || ob != BKE_view_layer_active_object_get(view_layer) ||
       ob->matbits == nullptr) {
     return OL_DRAWSEL_NONE; /* just paranoia */
@@ -1084,7 +1107,7 @@ eOLDrawState tree_element_active_state_get(const TreeViewContext *tvc,
       return OL_DRAWSEL_NONE;
       break;
     case ID_MA:
-      return tree_element_active_material_get(tvc->view_layer, te);
+      return tree_element_active_material_get(tvc->scene, tvc->view_layer, te);
     case ID_WO:
       return tree_element_active_world_get(tvc->scene, te);
     case ID_CA:
@@ -1100,9 +1123,9 @@ eOLDrawState tree_element_type_active_state_get(const bContext *C,
 {
   switch (tselem->type) {
     case TSE_DEFGROUP:
-      return tree_element_defgroup_state_get(tvc->view_layer, te, tselem);
+      return tree_element_defgroup_state_get(tvc->scene, tvc->view_layer, te, tselem);
     case TSE_BONE:
-      return tree_element_bone_state_get(tvc->view_layer, te, tselem);
+      return tree_element_bone_state_get(tvc->scene, tvc->view_layer, te, tselem);
     case TSE_EBONE:
       return tree_element_ebone_state_get(te);
     case TSE_MODIFIER:
@@ -1112,7 +1135,7 @@ eOLDrawState tree_element_type_active_state_get(const bContext *C,
     case TSE_LINKED_PSYS:
       return OL_DRAWSEL_NONE;
     case TSE_POSE_BASE:
-      return tree_element_pose_state_get(tvc->view_layer, tselem);
+      return tree_element_pose_state_get(tvc->scene, tvc->view_layer, tselem);
     case TSE_POSE_CHANNEL:
       return tree_element_posechannel_state_get(tvc->ob_pose, te, tselem);
     case TSE_CONSTRAINT_BASE:
@@ -1121,7 +1144,7 @@ eOLDrawState tree_element_type_active_state_get(const bContext *C,
     case TSE_R_LAYER:
       return tree_element_viewlayer_state_get(C, te);
     case TSE_POSEGRP:
-      return tree_element_posegroup_state_get(tvc->view_layer, te, tselem);
+      return tree_element_posegroup_state_get(tvc->scene, tvc->view_layer, te, tselem);
     case TSE_SEQUENCE:
       return tree_element_sequence_state_get(tvc->scene, te);
     case TSE_SEQUENCE_DUP:
@@ -1402,6 +1425,7 @@ static void do_outliner_item_activate_tree_element(bContext *C,
     }
     else if ((te->idcode == ID_GR) && (space_outliner->outlinevis != SO_VIEW_LAYER)) {
       Collection *gr = (Collection *)tselem->id;
+      BKE_view_layer_synced_ensure(tvc->scene, tvc->view_layer);
 
       if (extend) {
         eObjectSelect_Mode sel = BA_SELECT;
@@ -1575,7 +1599,9 @@ static bool outliner_is_co_within_active_mode_column(bContext *C,
                                                      SpaceOutliner *space_outliner,
                                                      const float view_mval[2])
 {
+  const Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
+  BKE_view_layer_synced_ensure(scene, view_layer);
   Object *obact = BKE_view_layer_active_object_get(view_layer);
 
   return outliner_is_co_within_mode_column(space_outliner, view_mval) && obact &&
diff --git a/source/blender/editors/space_outliner/outliner_sync.cc b/source/blender/editors/space_outliner/outliner_sync.cc
index 8f1c15873b4..995c83b589d 100644
--- a/source/blender/editors/space_outliner/outliner_sync.cc
+++ b/source/blender/editors/space_outliner/outliner_sync.cc
@@ -225,7 +225,8 @@ static void outliner_select_sync_to_object(ViewLayer *view_layer,
   }
 }
 
-static void outliner_select_sync_to_edit_bone(ViewLayer *view_layer,
+static void outliner_select_sync_to_edit_bone(const Scene *scene,
+                                              ViewLayer *view_layer,
                                               TreeElement *te,
                                               TreeStoreElem *tselem,
                                               GSet *selected_ebones)
@@ -250,6 +251,7 @@ static void outliner_select_sync_to_edit_bone(ViewLayer *view_layer,
 
   /* Tag if selection changed */
   if (bone_flag != ebone->flag) {
+    BKE_view_layer_synced_ensure(scene, view_layer);
     Object *obedit = BKE_view_layer_edit_object_get(view_layer);
     DEG_id_tag_update(&arm->id, ID_RECALC_SELECT);
     WM_main_add_notifier(NC_OBJECT | ND_BONE_SELECT, obedit);
@@ -318,7 +320,8 @@ static void outliner_sync_selection_from_outliner(Scene *scene,
     }
     else if (tselem->type == TSE_EBONE) {
       if (sync_types->edit_bone) {
-        outliner_select_sync_to_edit_bone(view_layer, te, tselem, selected_items->edit_bones);
+        outliner_select_sync_to_edit_bone(
+            scene, view_layer, te, tselem, selected_items->edit_bones);
       }
     }
     else if (tselem->type == TSE_POSE_CHANNEL) {
@@ -388,12 +391,14 @@ void ED_outliner_select_sync_from_outliner(bContext *C, SpaceOutliner *space_out
 
 namespace blender::ed::outliner {
 
-static void outliner_select_sync_from_object(ViewLayer *view_layer,
+static void outliner_select_sync_from_object(const Scene *scene,
+                                             ViewLayer *view_layer,
                                              Object *obact,
                                              TreeElement *te,
                                              TreeStoreElem *tselem)
 {
   Object *ob = (Object *)tselem->id;
+  BKE_view_layer_synced_ensure(scene, view_layer);
   Base *base = (te->directdata) ? (Base *)te->directdata :
                                   BKE_view_layer_base_find(view_layer, ob);
   const bool is_selected = (base != nullptr) && ((base->flag & BASE_SELECTED) != 0);
@@ -487,7 +492,8 @@ struct SyncSelectActiveData {
 };
 
 /** Sync select and active flags from active view layer, bones, and sequences to the outliner. */
-static void outliner_sync_selection_to_outliner(ViewLayer *view_layer,
+static void outliner_sync_selection_to_outliner(const Scene *scene,
+                                                ViewLayer *view_layer,
                                                 SpaceOutliner *space_outliner,
                                                 ListBase *tree,
                                                 SyncSelectActiveData *active_data,
@@ -498,7 +504,7 @@ static void outliner_sync_selection_to_outliner(ViewLayer *view_layer,
 
     if ((tselem->type == TSE_SOME_ID) && te->idcode == ID_OB) {
       if (sync_types->object) {
-        outliner_select_sync_from_object(view_layer, active_data->object, te, tselem);
+        outliner_select_sync_from_object(scene, view_layer, active_data->object, te, tselem);
       }
     }
     else if (tselem->type == TSE_EBONE) {
@@ -522,7 +528,7 @@ static void outliner_sync_selection_to_outliner(ViewLayer *view_layer,
 
     /* Sync subtree elements */
     outliner_sync_selection_to_outliner(
-        view_layer, space_outliner, &te->subtree, active_data, sync_types);
+        scene, view_layer, space_outliner, &te->subtree, active_data, sync_types);
   }
 }
 
@@ -531,6 +537,7 @@ static void get_sync_select_active_data(const bContext *C, SyncSelectActiveData
 {
   Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
+  BKE_view_layer_synced_ensure(scene, view_layer);
   active_data->object = BKE_view_layer_active_object_get(view_layer);
   active_data->edit_bone = CTX_data_active_bone(C);
   active_data->pose_channel = CTX_data_active_pose_bone(C);
@@ -545,6 +552,7 @@ void outliner_sync_selection(const bContext *C, SpaceOutliner *space_outliner)
       C, space_outliner, &sync_types);
 
   if (sync_required) {
+    const Scene *scene = CTX_data_scene(C);
     ViewLayer *view_layer = CTX_data_view_layer(C);
 
     /* Store active object, bones, and sequence */
@@ -552,7 +560,7 @@ void outliner_sync_selection(const bContext *C, SpaceOutliner *space_outliner)
     get_sync_select_active_data(C, &active_data);
 
     outliner_sync_selection_to_outliner(
-        view_layer, space_outliner, &space_outliner->tree, &active_data, &sync_types);
+        scene, view_layer, space_outliner, &space_outliner->tree, &active_data, &sync_types);
 
     /* Keep any un-synced data in the dirty flag. */
     if (sync_types.object) {
diff --git a/source/blender/editors/space_outliner/outliner_tools.cc b/source/blender/editors/space_outliner/outliner_tools.cc
index bab5b945d43..1628945c4cd 100644
--- a/source/blender/editors/space_outliner/outliner_tools.cc
+++ b/source/blender/editors/space_outliner/outliner_tools.cc
@@ -782,8 +782,10 @@ static void object_select_fn(bContext *C,
                              TreeStoreElem *tselem,
                              void *UNUSED(user_data))
 {
+  const Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
   Object *ob = (Object *)tselem->id;
+  BKE_view_layer_synced_ensure(scene, view_layer);
   Base *base = BKE_view_layer_base_find(view_layer, ob);
 
   if (base) {
@@ -820,8 +822,10 @@ static void object_deselect_fn(bContext *C,
                                TreeStoreElem *tselem,
                                void *UNUSED(user_data))
 {
+  const Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
   Object *ob = (Object *)tselem->id;
+  BKE_view_layer_synced_ensure(scene, view_layer);
   Base *base = BKE_view_layer_base_find(view_layer, ob);
 
   if (base) {
@@ -1317,6 +1321,7 @@ static void id_override_library_clear_single_fn(bContext *C,
    * override. */
   if (BKE_lib_override_library_is_hierarchy_leaf(bmain, id)) {
     bool do_remap_active = false;
+    BKE_view_layer_synced_ensure(CTX_data_scene(C), view_layer);
     if (BKE_view_layer_active_object_get(view_layer) == reinterpret_cast<Object *>(id)) {
       BLI_assert(GS(id->name) == ID_OB);
       do_remap_active = true;
@@ -2108,9 +2113,10 @@ static Base *outliner_batch_delete_hierarchy(
   if (!base) {
     return nullptr;
   }
-
+  BKE_view_layer_synced_ensure(scene, view_layer);
   object = base->object;
-  for (child_base = static_cast<Base *>(view_layer->object_bases.first); child_base;
+  for (child_base = static_cast<Base *>(BKE_view_layer_object_bases_get(view_layer)->first);
+       child_base;
        child_base = base_next) {
     base_next = child_base->next;
     for (parent = child_base->object->parent; parent && (parent != object);
@@ -2160,6 +2166,7 @@ static void object_batch_delete_hierarchy_fn(bContext *C,
   ViewLayer *view_layer = CTX_data_view_layer(C);
   Object *obedit = CTX_data_edit_object(C);
 
+  BKE_view_layer_synced_ensure(scene, view_layer);
   Base *base = BKE_view_layer_base_find(view_layer, ob);
 
   if (base) {
@@ -2384,7 +2391,8 @@ static int outliner_delete_exec(bContext *C, wmOperator *op)
   SpaceOutliner *space_outliner = CTX_wm_space_outliner(C);
   struct wmMsgBus *mbus = CTX_wm_message_bus(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
-  const Base *basact_prev = view_layer->basact;
+  BKE_view_layer_synced_ensure(scene, view_layer);
+  const Base *basact_prev = BKE_view_layer_active_base_get(view_layer);
 
   const bool delete_hierarchy = RNA_boolean_get(op->ptr, "hierarchy");
 
@@ -2428,7 +2436,8 @@ static int outliner_delete_exec(bContext *C, wmOperator *op)
   DEG_id_tag_update(&scene->id, ID_RECALC_COPY_ON_WRITE);
   DEG_relations_tag_update(bmain);
 
-  if (basact_prev != view_layer->basact) {
+  BKE_view_layer_synced_ensure(scene, view_layer);
+  if (basact_prev != BKE_view_layer_active_base_get(view_layer)) {
     WM_event_add_notifier(C, NC_SCENE | ND_OB_ACTIVE, scene);
     WM_msg_publish_rna_prop(mbus, &scene->id, view_layer, LayerObjects, active);
   }
diff --git a/source/blender/editors/space_outliner/outliner_tree.cc b/source/blender/editors/space_outliner/outliner_tree.cc
index a8f469c135a..8a2ff8c2ece 100644
--- a/source/blender/editors/space_outliner/outliner_tree.cc
+++ b/source/blender/editors/space_outliner/outliner_tree.cc
@@ -1395,7 +1395,8 @@ static int outliner_exclude_filter_get(const SpaceOutliner *space_outliner)
   return exclude_filter;
 }
 
-static bool outliner_element_visible_get(ViewLayer *view_layer,
+static bool outliner_element_visible_get(const Scene *scene,
+                                         ViewLayer *view_layer,
                                          TreeElement *te,
                                          const int exclude_filter)
 {
@@ -1450,6 +1451,7 @@ static bool outliner_element_visible_get(ViewLayer *view_layer,
 
     if (exclude_filter & SO_FILTER_OB_STATE) {
       if (base == nullptr) {
+        BKE_view_layer_synced_ensure(scene, view_layer);
         base = BKE_view_layer_base_find(view_layer, ob);
 
         if (base == nullptr) {
@@ -1475,7 +1477,8 @@ static bool outliner_element_visible_get(ViewLayer *view_layer,
       }
       else {
         BLI_assert(exclude_filter & SO_FILTER_OB_STATE_ACTIVE);
-        if (base != view_layer->basact) {
+        BKE_view_layer_synced_ensure(scene, view_layer);
+        if (base != BKE_view_layer_active_base_get(view_layer)) {
           is_visible = false;
         }
       }
@@ -1557,6 +1560,7 @@ static TreeElement *outliner_extract_children_from_subtree(TreeElement *element,
 }
 
 static int outliner_filter_subtree(SpaceOutliner *space_outliner,
+                                   const Scene *scene,
                                    ViewLayer *view_layer,
                                    ListBase *lb,
                                    const char *search_string,
@@ -1567,18 +1571,18 @@ static int outliner_filter_subtree(SpaceOutliner *space_outliner,
 
   for (te = static_cast<TreeElement *>(lb->first); te; te = te_next) {
     te_next = te->next;
-    if ((outliner_element_visible_get(view_layer, te, exclude_filter) == false)) {
+    if ((outliner_element_visible_get(scene, view_layer, te, exclude_filter) == false)) {
       /* Don't free the tree, but extract the children from the parent and add to this tree. */
       /* This also needs filtering the subtree prior (see T69246). */
       outliner_filter_subtree(
-          space_outliner, view_layer, &te->subtree, search_string, exclude_filter);
+          space_outliner, scene, view_layer, &te->subtree, search_string, exclude_filter);
       te_next = outliner_extract_children_from_subtree(te, lb);
       continue;
     }
     if ((exclude_filter & SO_FILTER_SEARCH) == 0) {
       /* Filter subtree too. */
       outliner_filter_subtree(
-          space_outliner, view_layer, &te->subtree, search_string, exclude_filter);
+          space_outliner, scene, view_layer, &te->subtree, search_string, exclude_filter);
       continue;
     }
 
@@ -1596,7 +1600,8 @@ static int outliner_filter_subtree(SpaceOutliner *space_outliner,
 
       if ((!TSELEM_OPEN(tselem, space_outliner)) ||
           outliner_filter_subtree(
-              space_outliner, view_layer, &te->subtree, search_string, exclude_filter) == 0) {
+              space_outliner, scene, view_layer, &te->subtree, search_string, exclude_filter) ==
+              0) {
         outliner_free_tree_element(te, lb);
       }
     }
@@ -1608,7 +1613,7 @@ static int outliner_filter_subtree(SpaceOutliner *space_outliner,
 
       /* filter subtree too */
       outliner_filter_subtree(
-          space_outliner, view_layer, &te->subtree, search_string, exclude_filter);
+          space_outliner, scene, view_layer, &te->subtree, search_string, exclude_filter);
     }
   }
 
@@ -1616,7 +1621,9 @@ static int outliner_filter_subtree(SpaceOutliner *space_outliner,
   return (BLI_listbase_is_empty(lb) == false);
 }
 
-static void outliner_filter_tree(SpaceOutliner *space_outliner, ViewLayer *view_layer)
+static void outliner_filter_tree(SpaceOutliner *space_outliner,
+                                 const Scene *scene,
+                                 ViewLayer *view_layer)
 {
   char search_buff[sizeof(((struct SpaceOutliner *)nullptr)->search_string) + 2];
   char *search_string;
@@ -1637,7 +1644,7 @@ static void outliner_filter_tree(SpaceOutliner *space_outliner, ViewLayer *view_
   }
 
   outliner_filter_subtree(
-      space_outliner, view_layer, &space_outliner->tree, search_string, exclude_filter);
+      space_outliner, scene, view_layer, &space_outliner->tree, search_string, exclude_filter);
 }
 
 static void outliner_clear_newid_from_main(Main *bmain)
@@ -1714,7 +1721,7 @@ void outliner_build_tree(Main *mainvar,
     outliner_collections_children_sort(&space_outliner->tree);
   }
 
-  outliner_filter_tree(space_outliner, view_layer);
+  outliner_filter_tree(space_outliner, scene, view_layer);
   outliner_restore_scrolling_position(space_outliner, region, &focus);
 
   /* `ID.newid` pointer is abused when building tree, DO NOT call #BKE_main_id_newptr_and_tag_clear
diff --git a/source/blender/editors/space_outliner/outliner_utils.cc b/source/blender/editors/space_outliner/outliner_utils.cc
index ff5292e2883..2deedccc29e 100644
--- a/source/blender/editors/space_outliner/outliner_utils.cc
+++ b/source/blender/editors/space_outliner/outliner_utils.cc
@@ -45,6 +45,7 @@ void outliner_viewcontext_init(const bContext *C, TreeViewContext *tvc)
   tvc->view_layer = CTX_data_view_layer(C);
 
   /* Objects. */
+  BKE_view_layer_synced_ensure(tvc->scene, tvc->view_layer);
   tvc->obact = BKE_view_layer_active_object_get(tvc->view_layer);
   if (tvc->obact != nullptr) {
     tvc->ob_edit = OBEDIT_FROM_OBACT(tvc->obact);
@@ -452,6 +453,7 @@ using namespace blender::ed::outliner;
 Base *ED_outliner_give_base_under_cursor(bContext *C, const int mval[2])
 {
   ARegion *region = CTX_wm_region(C);
+  const Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
   SpaceOutliner *space_outliner = CTX_wm_space_outliner(C);
   TreeElement *te;
@@ -465,6 +467,7 @@ Base *ED_outliner_give_base_under_cursor(bContext *C, const int mval[2])
     TreeStoreElem *tselem = TREESTORE(te);
     if ((tselem->type == TSE_SOME_ID) && (te->idcode == ID_OB)) {
       Object *ob = (Object *)tselem->id;
+      BKE_view_layer_synced_ensure(scene, view_layer);
       base = (te->directdata) ? (Base *)te->directdata : BKE_view_layer_base_find(view_layer, ob);
     }
   }
diff --git a/source/blender/editors/space_outliner/tree/tree_display.hh b/source/blender/editors/space_outliner/tree/tree_display.hh
index 295eeb59eaa..13b46651562 100644
--- a/source/blender/editors/space_outliner/tree/tree_display.hh
+++ b/source/blender/editors/space_outliner/tree/tree_display.hh
@@ -105,6 +105,7 @@ class AbstractTreeDisplay {
  * \brief Tree-Display for the View Layer display mode.
  */
 class TreeDisplayViewLayer final : public AbstractTreeDisplay {
+  Scene *scene_ = nullptr;
   ViewLayer *view_layer_ = nullptr;
   bool show_objects_ = true;
 
diff --git a/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc b/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc
index c8869d90eca..66c1fa34914 100644
--- a/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc
+++ b/source/blender/editors/space_outliner/tree/tree_display_view_layer.cc
@@ -64,6 +64,7 @@ ListBase TreeDisplayViewLayer::buildTree(const TreeSourceData &source_data)
 {
   ListBase tree = {nullptr};
   Scene *scene = source_data.scene;
+  scene_ = scene;
   show_objects_ = !(space_outliner_.filter & SO_FILTER_NO_OBJECT);
 
   for (auto *view_layer : ListBaseWrapper<ViewLayer>(scene->view_layers)) {
@@ -96,7 +97,8 @@ void TreeDisplayViewLayer::add_view_layer(Scene &scene, ListBase &tree, TreeElem
 
   if (space_outliner_.filter & SO_FILTER_NO_COLLECTION) {
     /* Show objects in the view layer. */
-    for (Base *base : List<Base>(view_layer_->object_bases)) {
+    BKE_view_layer_synced_ensure(&scene, view_layer_);
+    for (Base *base : List<Base>(*BKE_view_layer_object_bases_get(view_layer_))) {
       TreeElement *te_object = outliner_add_element(
           &space_outliner_, &tree, base->object, parent, TSE_SOME_ID, 0);
       te_object->directdata = base;
@@ -166,6 +168,7 @@ void TreeDisplayViewLayer::add_layer_collection_objects(ListBase &tree,
                                                         LayerCollection &lc,
                                                         TreeElement &ten)
 {
+  BKE_view_layer_synced_ensure(scene_, view_layer_);
   for (CollectionObject *cob : List<CollectionObject>(lc.collection->gobject)) {
     Base *base = BKE_view_layer_base_find(view_layer_, cob->ob);
     TreeElement *te_object = outliner_add_element(