Fix #117970: Fix RNA checks for animatable properties, add a check for drivable ones.

The `RNA_property_animateable` would check for some conditions, where it
is not valid to add or edit animations (e.g. if using a linked Action
ID...).

Add a new `RNA_property_drivable`, which is essentially a call to
`RNA_property_animateable` with extra checks in liboverride cases, as
drivers are stored directly in the AnimData struct, instead of their own
dedicated ID.

Pull Request: https://projects.blender.org/blender/blender/pulls/118809

source/blender/editors/animation/drivers.cc

@@ -891,7 +891,7 @@ static const EnumPropertyItem *driver_mapping_type_itemf(bContext *C,
 
   UI_context_active_but_prop_get(C, &ptr, &prop, &index);
 
-  if (ptr.owner_id && ptr.data && prop && RNA_property_animateable(&ptr, prop)) {
+  if (ptr.owner_id && ptr.data && prop && RNA_property_drivable(&ptr, prop)) {
     const bool is_array = RNA_property_array_check(prop);
 
     while (input->identifier) {
@@ -927,7 +927,7 @@ static bool add_driver_button_poll(bContext *C)
   if (!(ptr.owner_id && ptr.data && prop)) {
     return false;
   }
-  if (!RNA_property_animateable(&ptr, prop)) {
+  if (!RNA_property_drivable(&ptr, prop)) {
     return false;
   }
 
@@ -952,7 +952,7 @@ static int add_driver_button_none(bContext *C, wmOperator *op, short mapping_typ
     index = -1;
   }
 
-  if (ptr.owner_id && ptr.data && prop && RNA_property_animateable(&ptr, prop)) {
+  if (ptr.owner_id && ptr.data && prop && RNA_property_drivable(&ptr, prop)) {
     short flags = CREATEDRIVER_WITH_DEFAULT_DVAR;
 
     if (const std::optional<std::string> path = RNA_path_from_ID_to_property(&ptr, prop)) {
@@ -1043,7 +1043,7 @@ static int add_driver_button_invoke(bContext *C, wmOperator *op, const wmEvent *
 
   UI_context_active_but_prop_get(C, &ptr, &prop, &index);
 
-  if (ptr.owner_id && ptr.data && prop && RNA_property_animateable(&ptr, prop)) {
+  if (ptr.owner_id && ptr.data && prop && RNA_property_drivable(&ptr, prop)) {
     /* 1) Create a new "empty" driver for this property */
     short flags = CREATEDRIVER_WITH_DEFAULT_DVAR;
     bool changed = false;
@@ -1181,7 +1181,7 @@ static int copy_driver_button_exec(bContext *C, wmOperator *op)
 
   UI_context_active_but_prop_get(C, &ptr, &prop, &index);
 
-  if (ptr.owner_id && ptr.data && prop && RNA_property_animateable(&ptr, prop)) {
+  if (ptr.owner_id && ptr.data && prop && RNA_property_drivable(&ptr, prop)) {
     if (const std::optional<std::string> path = RNA_path_from_ID_to_property(&ptr, prop)) {
       /* only copy the driver for the button that this was involved for */
       changed = ANIM_copy_driver(op->reports, ptr.owner_id, path->c_str(), index, 0);
@@ -1220,7 +1220,7 @@ static int paste_driver_button_exec(bContext *C, wmOperator *op)
 
   UI_context_active_but_prop_get(C, &ptr, &prop, &index);
 
-  if (ptr.owner_id && ptr.data && prop && RNA_property_animateable(&ptr, prop)) {
+  if (ptr.owner_id && ptr.data && prop && RNA_property_drivable(&ptr, prop)) {
     if (const std::optional<std::string> path = RNA_path_from_ID_to_property(&ptr, prop)) {
       /* only copy the driver for the button that this was involved for */
       changed = ANIM_paste_driver(op->reports, ptr.owner_id, path->c_str(), index, 0);

source/blender/editors/interface/eyedroppers/eyedropper_driver.cc

@@ -54,8 +54,7 @@ static bool driverdropper_init(bContext *C, wmOperator *op)
   uiBut *but = UI_context_active_but_prop_get(C, &ddr->ptr, &ddr->prop, &ddr->index);
 
   if ((ddr->ptr.data == nullptr) || (ddr->prop == nullptr) ||
-      (RNA_property_editable(&ddr->ptr, ddr->prop) == false) ||
-      (RNA_property_animateable(&ddr->ptr, ddr->prop) == false) || (but->flag & UI_BUT_DRIVEN))
+      (RNA_property_drivable(&ddr->ptr, ddr->prop) == false) || (but->flag & UI_BUT_DRIVEN))
   {
     MEM_freeN(ddr);
     return false;

source/blender/makesrna/RNA_access.hh

@@ -305,6 +305,12 @@ bool RNA_property_editable_flag(const PointerRNA *ptr, PropertyRNA *prop);
 
 bool RNA_property_animateable(const PointerRNA *ptr, PropertyRNA *prop);
 bool RNA_property_animated(PointerRNA *ptr, PropertyRNA *prop);
+/**
+ * With LibOverrides, a property may be animatable, but not drivable (in case the reference data
+ * already has an animation data, its Action can ba an editable local ID, but the drivers are
+ * directly stored in the animdata, overriding these is not supported currently).
+ */
+bool RNA_property_drivable(const PointerRNA *ptr, PropertyRNA *prop);
 /**
  * \note Does not take into account editable status, this has to be checked separately
  * (using #RNA_property_editable_flag() usually).

source/blender/makesrna/intern/rna_access.cc

@@ -17,6 +17,7 @@
 #include "MEM_guardedalloc.h"
 
 #include "DNA_ID.h"
+#include "DNA_anim_types.h"
 #include "DNA_constraint_types.h"
 #include "DNA_modifier_types.h"
 #include "DNA_scene_types.h"
@@ -2191,13 +2192,45 @@ bool RNA_property_animateable(const PointerRNA *ptr, PropertyRNA *prop)
     return false;
   }
 
+  /* Linked or LibOverride Action IDs are not editable at the FCurve level. */
+  if (ptr->owner_id) {
+    AnimData *anim_data = BKE_animdata_from_id(ptr->owner_id);
+    if (anim_data && anim_data->action &&
+        (ID_IS_LINKED(anim_data->action) || ID_IS_OVERRIDE_LIBRARY(anim_data->action)))
+    {
+      return false;
+    }
+  }
+
   prop = rna_ensure_property(prop);
 
   if (!(prop->flag & PROP_ANIMATABLE)) {
     return false;
   }
 
-  return (prop->flag & PROP_EDITABLE) != 0;
+  return RNA_property_editable(const_cast<PointerRNA *>(ptr), prop);
+}
+
+bool RNA_property_drivable(const PointerRNA *ptr, PropertyRNA *prop)
+{
+  if (!RNA_property_animateable(ptr, prop)) {
+    return false;
+  }
+
+  /* LibOverrides can only get drivers if their animdata (if any) was created for the local
+   * liboverride, and there is none in the linked reference.
+   *
+   * See also #rna_AnimaData_override_apply. */
+  if (ptr->owner_id && ID_IS_OVERRIDE_LIBRARY(ptr->owner_id)) {
+    IDOverrideLibrary *liboverride = BKE_lib_override_library_get(
+        nullptr, ptr->owner_id, nullptr, nullptr);
+    AnimData *linked_reference_anim_data = BKE_animdata_from_id(liboverride->reference);
+    if (linked_reference_anim_data) {
+      return false;
+    }
+  }
+
+  return true;
 }
 
 bool RNA_property_animated(PointerRNA *ptr, PropertyRNA *prop)