Anim: New/Un-assign Slot operators

Add two new operators, `anim.slot_new_for_id` and
`anim.slot_unassign_from_id`. These are used in the Action editor and
the Animation panels in the Properties editor, to respectively create a
new Action Slot for an ID and to unassign whatever slot is currently
assigned to that ID.

The latter operator also replaces the C++ operator
`anim.slot_unassign_object`, which was specifically made for the
Dopesheet header. The Python ones are generic enough to be used there
too.

Pull Request: #126943

scripts/startup/bl_operators/anim.py

@@ -668,6 +668,69 @@ class ARMATURE_OT_collection_remove_unused(Operator):
         )
 
 
+class ANIM_OT_slot_new_for_id(Operator):
+    """Create a new Action Slot for an ID.
+
+    Note that _which_ ID should get this slot must be set in the 'animated_id' context pointer, using:
+
+    >>> layout.context_pointer_set("animated_id", animated_id)
+    """
+    bl_idname = "anim.slot_new_for_id"
+    bl_label = "New Slot"
+    bl_description = "Create a new action slot for this data-block, to hold its animation"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    @classmethod
+    def poll(cls, context):
+        animated_id = getattr(context, 'animated_id', None)
+        if not animated_id:
+            return False
+        if not animated_id.animation_data or not animated_id.animation_data.action:
+            cls.poll_message_set("An action slot can only be created when an action was assigned")
+            return False
+        if not animated_id.animation_data.action.is_action_layered:
+            cls.poll_message_set("Action slots are only supported by layered Actions. Upgrade this Action first")
+            return False
+        return True
+
+    def execute(self, context):
+        animated_id = getattr(context, 'animated_id', None)
+
+        action = animated_id.animation_data.action
+        slot = action.slots.new(for_id=animated_id)
+        animated_id.animation_data.action_slot = slot
+        return {'FINISHED'}
+
+
+class ANIM_OT_slot_unassign_from_id(Operator):
+    """Un-assign the assigned Action Slot from an ID.
+
+    Note that _which_ ID should get this slot unassigned must be set in the
+    'animated_id' context pointer, using:
+
+    >>> layout.context_pointer_set("animated_id", animated_id)
+    """
+    bl_idname = "anim.slot_unassign_from_id"
+    bl_label = "Unassign Slot"
+    bl_description = "Un-assign the action slot, effectively making this data-block non-animated"
+    bl_options = {'REGISTER', 'UNDO'}
+
+    @classmethod
+    def poll(cls, context):
+        animated_id = getattr(context, 'animated_id', None)
+        if not animated_id:
+            return False
+        if not animated_id.animation_data or not animated_id.animation_data.action_slot:
+            cls.poll_message_set("This data-block has no Action slot assigned")
+            return False
+        return True
+
+    def execute(self, context):
+        animated_id = getattr(context, 'animated_id', None)
+        animated_id.animation_data.action_slot = None
+        return {'FINISHED'}
+
+
 classes = (
     ANIM_OT_keying_set_export,
     NLA_OT_bake,
@@ -677,4 +740,6 @@ classes = (
     ARMATURE_OT_collection_show_all,
     ARMATURE_OT_collection_unsolo_all,
     ARMATURE_OT_collection_remove_unused,
+    ANIM_OT_slot_new_for_id,
+    ANIM_OT_slot_unassign_from_id,
 )

scripts/startup/bl_ui/space_dopesheet.py

@@ -225,8 +225,8 @@ class DOPESHEET_HT_header(Header):
 # Header for "normal" dopesheet editor modes (e.g. Dope Sheet, Action, Shape Keys, etc.)
 class DOPESHEET_HT_editor_buttons:
 
-    @staticmethod
-    def draw_header(context, layout):
+    @classmethod
+    def draw_header(cls, context, layout):
         st = context.space_data
         tool_settings = context.tool_settings
 
@@ -243,19 +243,7 @@ class DOPESHEET_HT_editor_buttons:
 
             if context.object:
                 layout.separator_spacer()
-                layout.template_action(context.object, new="action.new", unlink="action.unlink")
-
-                # Show slot selector.
-                if context.preferences.experimental.use_animation_baklava:
-                    # context.space_data.action comes from the active object.
-                    adt = context.object and context.object.animation_data
-                    if adt and st.action and st.action.is_action_layered:
-                        layout.template_search(
-                            adt, "action_slot",
-                            adt, "action_slots",
-                            new="anim.slot_new_for_object",
-                            unlink="anim.slot_unassign_object",
-                        )
+                cls._draw_action_selector(context, layout)
 
         # Layer management
         if st.mode == 'GPENCIL':
@@ -318,6 +306,27 @@ class DOPESHEET_HT_editor_buttons:
             panel="DOPESHEET_PT_proportional_edit",
         )
 
+    @staticmethod
+    def _draw_action_selector(context, layout):
+        layout.template_action(context.object, new="action.new", unlink="action.unlink")
+
+        if not context.preferences.experimental.use_animation_baklava:
+            return
+
+        adt = context.object and context.object.animation_data
+        if not adt or not adt.action or not adt.action.is_action_layered:
+            return
+
+        # Store the animated ID in the context, so that the new/unlink operators
+        # have access to it.
+        layout.context_pointer_set("animated_id", context.object)
+        layout.template_search(
+            adt, "action_slot",
+            adt, "action_slots",
+            new="anim.slot_new_for_id",
+            unlink="anim.slot_unassign_from_id",
+        )
+
 
 class DOPESHEET_PT_snapping(Panel):
     bl_space_type = 'DOPESHEET_EDITOR'

scripts/startup/bl_ui/space_properties.py

@@ -125,11 +125,12 @@ class PropertiesAnimationMixin:
 
         # Only show the slot selector when a layered Action is assigned.
         if adt.action.is_action_layered:
+            layout.context_pointer_set("animated_id", animated_id)
             layout.template_search(
                 adt, "action_slot",
                 adt, "action_slots",
-                new="",  # TODO: add this operator.
-                unlink="",  # TODO: add this operator.
+                new="anim.slot_new_for_id",
+                unlink="anim.slot_unassign_from_id",
             )
 
 

source/blender/editors/animation/anim_ops.cc

@@ -715,7 +715,7 @@ static void ANIM_OT_scene_range_frame(wmOperatorType *ot)
 /** \} */
 
 /* -------------------------------------------------------------------- */
-/** \name Slots
+/** \name Conversion
  * \{ */
 
 static bool slot_new_for_object_poll(bContext *C)
@@ -770,49 +770,6 @@ static void ANIM_OT_slot_new_for_object(wmOperatorType *ot)
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-static bool slot_unassign_object_poll(bContext *C)
-{
-  Object *object = CTX_data_active_object(C);
-  if (!object) {
-    return false;
-  }
-
-  AnimData *adt = BKE_animdata_from_id(&object->id);
-  if (!adt) {
-    return false;
-  }
-
-  return adt->slot_handle != blender::animrig::Slot::unassigned;
-}
-
-static int slot_unassign_object_exec(bContext *C, wmOperator * /*op*/)
-{
-  using namespace blender;
-
-  Object *object = CTX_data_active_object(C);
-  animrig::unassign_slot(object->id);
-
-  DEG_relations_tag_update(CTX_data_main(C));
-  WM_event_add_notifier(C, NC_ANIMATION | ND_ANIMCHAN, nullptr);
-  return OPERATOR_FINISHED;
-}
-
-static void ANIM_OT_slot_unassign_object(wmOperatorType *ot)
-{
-  /* identifiers */
-  ot->name = "Unassign Slot";
-  ot->idname = "ANIM_OT_slot_unassign_object";
-  ot->description =
-      "Clear the assigned action slot, effectively making this data-block non-animated";
-
-  /* api callbacks */
-  ot->exec = slot_unassign_object_exec;
-  ot->poll = slot_unassign_object_poll;
-
-  /* flags */
-  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-}
-
 static int convert_action_exec(bContext *C, wmOperator * /*op*/)
 {
   using namespace blender;
@@ -926,7 +883,6 @@ void ED_operatortypes_anim()
   WM_operatortype_append(ANIM_OT_keying_set_active_set);
 
   WM_operatortype_append(ANIM_OT_slot_new_for_object);
-  WM_operatortype_append(ANIM_OT_slot_unassign_object);
   WM_operatortype_append(ANIM_OT_convert_legacy_action);
 }