LibOverride: Abstract a bit handling of local items of RNA collections.

RNA collections that support insertion of new items in liboverride
data-block need a special way to distiguish between locale and
orig-from-linked items (since some operations are allowed on the forer,
but no the latter).

In future we want a proper solution to abstract that at the
`BKE_lib_override` level, but for now we need to add some code for each
case.

Note that this commit also fixes a few potential issues with GPencil
modifiers, and constraints, regarding their handling of local overrides.

1 files changed, 13 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/gpencil_modifier.c b/source/blender/blenkernel/intern/gpencil_modifier.c
index 09f9e9e891c..7425a1a5f7a 100644
--- a/source/blender/blenkernel/intern/gpencil_modifier.c
+++ b/source/blender/blenkernel/intern/gpencil_modifier.c
@@ -531,6 +531,19 @@ void BKE_gpencil_modifier_set_error(GpencilModifierData *md, const char *_format
 }
 
 /**
+ * Check whether given modifier is local when the object is a library override.
+ *
+ * \param gmd May be NULL, in which case we consider it as a non-local modifier case.
+ *
+ * \note This check is only valid for a liboverride data-block, it always return \a true otherwise.
+ */
+bool BKE_gpencil_modifier_is_local_in_liboverride(const Object *ob, const GpencilModifierData *gmd)
+{
+  return (!ID_IS_OVERRIDE_LIBRARY(ob) ||
+          (gmd != NULL && (gmd->flag & eGpencilModifierFlag_OverrideLibrary_Local) != 0));
+}
+
+/**
  * Link grease pencil modifier related IDs.
  * \param ob: Grease pencil object
  * \param walk: Walk option