D14823: Adds operator to duplicate the active color attribute layer

Fixes T97706

Adds operator to duplicate the active color attribute layer.
Adds `"Color Attribute Specials"` menu to color attribute ui to access the `"geometry.color_attribute_duplicate"` operator.
Internally adds a function that duplicates a referenced CustomDataLayer
- `BKE_id_attribute_duplicate` mostly copies the existing `BKE_id_attribute_new`
- but gets the type and domain from the referenced layer
- and copies the data from the old layer into the new layer

Reviewed By: Joseph Eagar & Hans Goudey & Julien Kaspar
Differential Revision: https://developer.blender.org/D14823
Ref D14823

1 files changed, 7 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_attribute.h b/source/blender/blenkernel/BKE_attribute.h
index 52a3e01026c..5755ddb3018 100644
--- a/source/blender/blenkernel/BKE_attribute.h
+++ b/source/blender/blenkernel/BKE_attribute.h
@@ -60,6 +60,13 @@ struct CustomDataLayer *BKE_id_attribute_new(
     struct ID *id, const char *name, int type, eAttrDomain domain, struct ReportList *reports);
 bool BKE_id_attribute_remove(struct ID *id, const char *name, struct ReportList *reports);
 
+/**
+ * Creates a duplicate attribute layer.
+ */
+struct CustomDataLayer *BKE_id_attribute_duplicate(struct ID *id,
+                                                   struct CustomDataLayer *layer,
+                                                   struct ReportList *reports);
+
 struct CustomDataLayer *BKE_id_attribute_find(const struct ID *id,
                                               const char *name,
                                               int type,