1 files changed, 39 insertions, 1 deletions
diff --git a/source/blender/editors/space_outliner/tree/tree_element_overrides.hh b/source/blender/editors/space_outliner/tree/tree_element_overrides.hh
index 1db46d9af1d..f8ca146a4ea 100644
--- a/source/blender/editors/space_outliner/tree/tree_element_overrides.hh
+++ b/source/blender/editors/space_outliner/tree/tree_element_overrides.hh
@@ -14,6 +14,7 @@
 
 struct ID;
 struct IDOverrideLibraryProperty;
+struct IDOverrideLibraryPropertyOperation;
 
 namespace blender::ed::outliner {
 
@@ -24,6 +25,11 @@ struct TreeElementOverridesData {
   PropertyRNA &override_rna_prop;
 
   bool is_rna_path_valid;
+
+  /* In case the property references a specific operation. Only used for collection overrides
+   * currently, where a single override may add/remove multiple collection items (only add
+   * currently). */
+  IDOverrideLibraryPropertyOperation *operation = nullptr;
 };
 
 class TreeElementOverridesBase final : public AbstractTreeElement {
@@ -38,7 +44,12 @@ class TreeElementOverridesBase final : public AbstractTreeElement {
   StringRefNull getWarning() const override;
 };
 
-class TreeElementOverridesProperty final : public AbstractTreeElement {
+/**
+ * Represent a single overridden property. Collection properties may support multiple override
+ * operations, e.g. to insert/remove multiple collection items. For these multiple operation cases,
+ * use #TreeElementOverridesPropertyOperation.
+ */
+class TreeElementOverridesProperty : public AbstractTreeElement {
  public:
   PointerRNA override_rna_ptr;
   PropertyRNA &override_rna_prop;
@@ -50,6 +61,33 @@ class TreeElementOverridesProperty final : public AbstractTreeElement {
   TreeElementOverridesProperty(TreeElement &legacy_te, TreeElementOverridesData &override_data);
 
   StringRefNull getWarning() const override;
+
+  bool isCollectionOperation() const;
+};
+
+/**
+ * Represent a single operation within an overridden property. While usually a single override
+ * property represents a single operation (changing the value), a single overridden collection
+ * property may have multiple operations, e.g. to insert or remove collection items.
+ *
+ * Inherits from the override property class since it should look/behave mostly the same.
+ */
+class TreeElementOverridesPropertyOperation final : public TreeElementOverridesProperty {
+  /** See #TreeElementOverridesData::operation. Operations are recreated as part of the diffing
+   * (e.g. on undo pushes) so store a copy of the data here. */
+  std::unique_ptr<IDOverrideLibraryPropertyOperation> operation_;
+
+ public:
+  TreeElementOverridesPropertyOperation(TreeElement &legacy_te,
+                                        TreeElementOverridesData &override_data);
+
+  /** Return a short string to display in the right column of the properties mode, indicating what
+   * the override operation did (e.g. added or removed a collection item). */
+  StringRefNull getOverrideOperationLabel() const;
+  std::optional<BIFIconID> getIcon() const override;
+
+ private:
+  std::optional<PointerRNA> get_collection_ptr() const;
 };
 
 }  // namespace blender::ed::outliner