Outliner: Port deform group elements to new tree-element code design

No user visible changes expected.

Part of #96713, continuation of work started in 249e4df110 and 2e221de4ce.
Refer to these for a motivation and design overview.

Adds new classes for deform group elements.

Pull Request: https://projects.blender.org/blender/blender/pulls/110003

source/blender/editors/space_outliner/CMakeLists.txt

@@ -50,6 +50,7 @@ set(SRC
   tree/tree_element_anim_data.cc
   tree/tree_element_bone.cc
   tree/tree_element_collection.cc
+  tree/tree_element_defgroup.cc
   tree/tree_element_driver.cc
   tree/tree_element_edit_bone.cc
   tree/tree_element_gpencil_layer.cc
@@ -82,6 +83,7 @@ set(SRC
   tree/tree_element_anim_data.hh
   tree/tree_element_bone.hh
   tree/tree_element_collection.hh
+  tree/tree_element_defgroup.hh
   tree/tree_element_driver.hh
   tree/tree_element_edit_bone.hh
   tree/tree_element_gpencil_layer.hh

source/blender/editors/space_outliner/outliner_intern.hh

@@ -29,6 +29,7 @@ struct TreeStoreElem;
 struct ViewLayer;
 struct bContext;
 struct bContextDataResult;
+struct bDeformGroup;
 struct bPoseChannel;
 struct ParticleSystem;
 struct View2D;
@@ -297,6 +298,11 @@ struct EditBoneElementCreateData {
   EditBone *ebone;
 };
 
+struct DeformGroupElementCreateData {
+  Object *object;
+  bDeformGroup *defgroup;
+};
+
 struct ParticleSystemElementCreateData {
   Object *object;
   ParticleSystem *psys;

source/blender/editors/space_outliner/outliner_tree.cc

@@ -245,6 +245,9 @@ TreeElement *outliner_add_element(SpaceOutliner *space_outliner,
   else if (type == TSE_EBONE) {
     id = static_cast<EditBoneElementCreateData *>(idv)->armature_id;
   }
+  else if (type == TSE_DEFGROUP) {
+    id = &static_cast<DeformGroupElementCreateData *>(idv)->object->id;
+  }
   else if (type == TSE_LINKED_PSYS) {
     id = &static_cast<ParticleSystemElementCreateData *>(idv)->object->id;
   }
@@ -306,6 +309,9 @@ TreeElement *outliner_add_element(SpaceOutliner *space_outliner,
   else if (ELEM(type, TSE_BONE, TSE_EBONE)) {
     /* pass */
   }
+  else if (ELEM(type, TSE_DEFGROUP, TSE_DEFGROUP_BASE)) {
+    /* pass */
+  }
   else if (type == TSE_LINKED_PSYS) {
     /* pass */
   }
@@ -358,7 +364,8 @@ TreeElement *outliner_add_element(SpaceOutliner *space_outliner,
                 TSE_SEQUENCE,
                 TSE_SEQ_STRIP,
                 TSE_SEQUENCE_DUP,
-                TSE_GENERIC_LABEL))
+                TSE_GENERIC_LABEL) ||
+           ELEM(type, TSE_DEFGROUP, TSE_DEFGROUP_BASE))
   {
     BLI_assert_msg(false, "Element type should already use new AbstractTreeElement design");
   }

source/blender/editors/space_outliner/tree/tree_element.cc

@@ -20,6 +20,7 @@
 #include "tree_element_anim_data.hh"
 #include "tree_element_bone.hh"
 #include "tree_element_collection.hh"
+#include "tree_element_defgroup.hh"
 #include "tree_element_driver.hh"
 #include "tree_element_edit_bone.hh"
 #include "tree_element_gpencil_layer.hh"
@@ -115,6 +116,14 @@ std::unique_ptr<AbstractTreeElement> AbstractTreeElement::createFromType(const i
       return std::make_unique<TreeElementEditBone>(
           legacy_te, *ebone_data->armature_id, *ebone_data->ebone);
     }
+    case TSE_DEFGROUP_BASE:
+      return std::make_unique<TreeElementDeformGroupBase>(legacy_te, *static_cast<Object *>(idv));
+    case TSE_DEFGROUP: {
+      DeformGroupElementCreateData *defgroup_data = static_cast<DeformGroupElementCreateData *>(
+          idv);
+      return std::make_unique<TreeElementDeformGroup>(
+          legacy_te, *defgroup_data->object, *defgroup_data->defgroup);
+    }
     case TSE_LINKED_PSYS: {
       ParticleSystemElementCreateData *psys_data = static_cast<ParticleSystemElementCreateData *>(
           idv);

source/blender/editors/space_outliner/tree/tree_element_defgroup.cc

@@ -0,0 +1,51 @@
+/* SPDX-FileCopyrightText: 2023 Blender Foundation
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup spoutliner
+ */
+
+#include "DNA_object_types.h"
+#include "DNA_outliner_types.h"
+
+#include "BKE_deform.h"
+
+#include "BLT_translation.h"
+
+#include "../outliner_intern.hh"
+
+#include "tree_element_defgroup.hh"
+
+namespace blender::ed::outliner {
+
+TreeElementDeformGroupBase::TreeElementDeformGroupBase(TreeElement &legacy_te, Object &object)
+    : AbstractTreeElement(legacy_te), object_(object)
+{
+  legacy_te.name = IFACE_("Vertex Groups");
+}
+
+void TreeElementDeformGroupBase::expand(SpaceOutliner &space_outliner) const
+{
+  const ListBase *defbase = BKE_object_defgroup_list(&object_);
+
+  int index;
+  LISTBASE_FOREACH_INDEX (bDeformGroup *, defgroup, defbase, index) {
+
+    DeformGroupElementCreateData defgroup_data = {&object_, defgroup};
+
+    outliner_add_element(
+        &space_outliner, &legacy_te_.subtree, &defgroup_data, &legacy_te_, TSE_DEFGROUP, index);
+  }
+}
+
+TreeElementDeformGroup::TreeElementDeformGroup(TreeElement &legacy_te,
+                                               Object & /* object */,
+                                               bDeformGroup &defgroup)
+    : AbstractTreeElement(legacy_te), /* object_(object), */ defgroup_(defgroup)
+{
+  legacy_te.name = defgroup_.name;
+  legacy_te.directdata = &defgroup_;
+}
+
+}  // namespace blender::ed::outliner

source/blender/editors/space_outliner/tree/tree_element_defgroup.hh

@@ -0,0 +1,35 @@
+/* SPDX-FileCopyrightText: 2023 Blender Foundation
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup spoutliner
+ */
+
+#pragma once
+
+#include "tree_element.hh"
+
+struct Object;
+struct bDeformGroup;
+
+namespace blender::ed::outliner {
+
+class TreeElementDeformGroupBase final : public AbstractTreeElement {
+  Object &object_;
+
+ public:
+  TreeElementDeformGroupBase(TreeElement &legacy_te, Object &object);
+  void expand(SpaceOutliner &) const override;
+};
+
+class TreeElementDeformGroup final : public AbstractTreeElement {
+  /* Not needed right now, avoid unused member variable warning. */
+  // Object &object_;
+  bDeformGroup &defgroup_;
+
+ public:
+  TreeElementDeformGroup(TreeElement &legacy_te, Object &object, bDeformGroup &defgroup);
+};
+
+}  // namespace blender::ed::outliner

source/blender/editors/space_outliner/tree/tree_element_id_object.cc

@@ -290,17 +290,8 @@ void TreeElementIDObject::expand_vertex_groups(SpaceOutliner &space_outliner) co
   if (BLI_listbase_is_empty(defbase)) {
     return;
   }
-  TreeElement *tenla = outliner_add_element(
+  outliner_add_element(
       &space_outliner, &legacy_te_.subtree, &object_, &legacy_te_, TSE_DEFGROUP_BASE, 0);
-  tenla->name = IFACE_("Vertex Groups");
-
-  int index;
-  LISTBASE_FOREACH_INDEX (bDeformGroup *, defgroup, defbase, index) {
-    TreeElement *ten = outliner_add_element(
-        &space_outliner, &tenla->subtree, &object_, tenla, TSE_DEFGROUP, index);
-    ten->name = defgroup->name;
-    ten->directdata = defgroup;
-  }
 }
 
 void TreeElementIDObject::expand_duplicated_group(SpaceOutliner &space_outliner) const