Fix #137041: Bugs with Slotted Actions and the Available Keying Set

Make the 'Available' keying set look at the F-Curves for the assigned
slot, instead of the backward-compatible API (which only sees the F-Curves
for the first slot).

Pull Request: https://projects.blender.org/blender/blender/pulls/137131

scripts/modules/bpy_extras/anim_utils.py

@@ -75,12 +75,19 @@ class BakeOptions:
     """Bake custom properties."""
 
 
-def action_get_channelbag_for_slot(action: Action, slot: ActionSlot) -> ActionChannelbag | None:
+def action_get_channelbag_for_slot(action: Action | None, slot: ActionSlot | None) -> ActionChannelbag | None:
     """
     Returns the first channelbag found for the slot.
     In case there are multiple layers or strips they are iterated until a
     channelbag for that slot is found. In case no matching channelbag is found, returns None.
     """
+    if not action or not slot:
+        # This is just for convenience so that you can call
+        # action_get_channelbag_for_slot(adt.action, adt.action_slot) and check
+        # the return value for None, without having to also check the action and
+        # the slot for None.
+        return None
+
     for layer in action.layers:
         for strip in layer.strips:
             channelbag = strip.channelbag(slot)

scripts/modules/keyingsets_utils.py

@@ -25,6 +25,8 @@ __all__ = (
 
 import bpy
 
+from bpy_extras import anim_utils
+
 ###########################
 # General Utilities
 
@@ -117,7 +119,11 @@ def RKS_GEN_available(_ksi, _context, ks, data):
 
     # for each F-Curve, include a path to key it
     # NOTE: we don't need to set the group settings here
-    for fcu in adt.action.fcurves:
+    cbag = anim_utils.action_get_channelbag_for_slot(adt.action, adt.action_slot)
+    if not cbag:
+        return
+
+    for fcu in cbag.fcurves:
         if basePath:
             if basePath in fcu.data_path:
                 ks.paths.add(id_block, fcu.data_path, index=fcu.array_index)

scripts/startup/keyingsets_builtins.py

@@ -17,6 +17,7 @@ are supported.
 import bpy
 import keyingsets_utils
 from bpy.types import KeyingSetInfo
+from bpy_extras import anim_utils
 
 ###############################
 # Built-In KeyingSets
@@ -355,7 +356,13 @@ class BUILTIN_KSI_Available(KeyingSetInfo):
         ob = context.active_object
         if ob:
             # TODO: this fails if one animation-less object is active, but many others are selected
-            return ob.animation_data and ob.animation_data.action
+            adt = ob.animation_data
+            if not adt:
+                return False
+            cbag = anim_utils.action_get_channelbag_for_slot(adt.action, adt.action_slot)
+            if not cbag:
+                return False
+            return bool(cbag.fcurves)
         else:
             return bool(context.selected_objects)
 

source/blender/makesrna/intern/rna_action.cc

@@ -745,9 +745,15 @@ static void rna_Channelbag_group_remove(ActionChannelbag *dna_channelbag,
 
 static ActionChannelbag *rna_ActionStrip_channelbag(ID *dna_action_id,
                                                     ActionStrip *self,
+                                                    ReportList *reports,
                                                     const ActionSlot *dna_slot,
                                                     const bool ensure)
 {
+  if (!dna_slot) {
+    BKE_report(reports, RPT_ERROR, "Cannot return channelbag when slot is None");
+    return nullptr;
+  }
+
   animrig::Action &action = reinterpret_cast<bAction *>(dna_action_id)->wrap();
   animrig::StripKeyframeData &strip_data = self->wrap().data<animrig::StripKeyframeData>(action);
   const animrig::Slot &slot = dna_slot->wrap();
@@ -2377,7 +2383,7 @@ static void rna_def_action_keyframe_strip(BlenderRNA *brna)
 
     /* Strip.channelbag(...). */
     func = RNA_def_function(srna, "channelbag", "rna_ActionStrip_channelbag");
-    RNA_def_function_flag(func, FUNC_USE_SELF_ID);
+    RNA_def_function_flag(func, FUNC_USE_SELF_ID | FUNC_USE_REPORTS);
     RNA_def_function_ui_description(func, "Find the ActionChannelbag for a specific Slot");
     parm = RNA_def_pointer(
         func, "slot", "ActionSlot", "Slot", "The slot for which to find the channelbag");