Anim: operator to move Slots to new action

This adds an operator that moves slots of slot channels selected in
the channel box to a new action.

All slots are moved together into that new action instead of
moving them into separate actions.
I think that's more reasonable because that way the "move slots into separate actions" is
still possible by selecting the slots one by one.
The "explode action" operator that does just that can be a separate operator.

The new action is named after the slot for the case when only one slot is moved.
When multiple slots are moved, the name "CombinedAction" is used.

This also adds a menu entry "Action" to the action editor.

Pull Request: https://projects.blender.org/blender/blender/pulls/128171

scripts/startup/bl_ui/space_dopesheet.py

@@ -402,6 +402,10 @@ class DOPESHEET_MT_editor_menus(Menu):
         else:
             layout.menu("DOPESHEET_MT_gpencil_key")
 
+        if st.mode in {'ACTION', 'SHAPEKEY'} and st.action is not None:
+            if context.preferences.experimental.use_animation_baklava:
+                layout.menu("DOPESHEET_MT_action")
+
 
 class DOPESHEET_MT_view(Menu):
     bl_label = "View"
@@ -581,6 +585,15 @@ class DOPESHEET_MT_channel(Menu):
         layout.operator("anim.channels_view_selected")
 
 
+class DOPESHEET_MT_action(Menu):
+    bl_label = "Action"
+
+    def draw(self, context):
+        layout = self.layout
+        layout.operator("anim.slot_channels_move_to_new_action")
+        layout.operator("anim.merge_animation")
+
+
 class DOPESHEET_MT_key(Menu):
     bl_label = "Key"
 
@@ -1044,6 +1057,7 @@ classes = (
     DOPESHEET_MT_select,
     DOPESHEET_MT_marker,
     DOPESHEET_MT_channel,
+    DOPESHEET_MT_action,
     DOPESHEET_MT_key,
     DOPESHEET_MT_key_transform,
     DOPESHEET_MT_gpencil_channel,

source/blender/animrig/ANIM_action.hh

@@ -109,7 +109,7 @@ class Action : public ::bAction {
   const Layer *layer(int64_t index) const;
   Layer *layer(int64_t index);
 
-  Layer &layer_add(StringRefNull name);
+  Layer &layer_add(std::optional<StringRefNull> name);
 
   /**
    * Remove the layer from this Action.

source/blender/animrig/intern/action.cc

@@ -245,10 +245,15 @@ Layer *Action::layer(const int64_t index)
   return &this->layer_array[index]->wrap();
 }
 
-Layer &Action::layer_add(const StringRefNull name)
+Layer &Action::layer_add(const std::optional<StringRefNull> name)
 {
   Layer &new_layer = ActionLayer_alloc();
-  STRNCPY_UTF8(new_layer.name, name.c_str());
+  if (name.has_value()) {
+    STRNCPY_UTF8(new_layer.name, name.value().c_str());
+  }
+  else {
+    STRNCPY_UTF8(new_layer.name, layer_default_name);
+  }
 
   grow_array_and_append<::ActionLayer *>(&this->layer_array, &this->layer_array_num, &new_layer);
   this->layer_active_index = this->layer_array_num - 1;

source/blender/editors/animation/anim_channels_edit.cc

@@ -65,6 +65,8 @@
 #include "WM_api.hh"
 #include "WM_types.hh"
 
+#include "BLT_translation.hh"
+
 /* -------------------------------------------------------------------- */
 /** \name Channel helper functions
  * \{ */
@@ -5185,6 +5187,105 @@ static void ANIM_OT_channels_bake(wmOperatorType *ot)
                   "Bake Modifiers into keyframes and delete them after");
 }
 
+#ifdef WITH_ANIM_BAKLAVA
+
+static int slot_channels_move_to_new_action_exec(bContext *C, wmOperator * /* op */)
+{
+  using namespace blender::animrig;
+  bAnimContext ac;
+
+  /* Get editor data. */
+  if (ANIM_animdata_get_context(C, &ac) == 0) {
+    return OPERATOR_CANCELLED;
+  }
+
+  ListBase anim_data = {nullptr, nullptr};
+  const eAnimFilter_Flags filter = (ANIMFILTER_SEL | ANIMFILTER_NODUPLIS |
+                                    ANIMFILTER_DATA_VISIBLE | ANIMFILTER_LIST_CHANNELS);
+
+  size_t anim_data_length = ANIM_animdata_filter(&ac, &anim_data, filter, ac.data, ac.datatype);
+
+  if (anim_data_length == 0) {
+    WM_report(RPT_WARNING, "No channels to operate on");
+    return OPERATOR_CANCELLED;
+  }
+
+  blender::Vector<std::pair<Slot *, bAction *>> slots;
+  LISTBASE_FOREACH (bAnimListElem *, ale, &anim_data) {
+    if (ale->type != ANIMTYPE_ACTION_SLOT) {
+      continue;
+    }
+    BLI_assert(GS(ale->fcurve_owner_id->name) == ID_AC);
+    bAction *owning_action = reinterpret_cast<bAction *>(ale->fcurve_owner_id);
+    slots.append({reinterpret_cast<Slot *>(ale->data), owning_action});
+  }
+  ANIM_animdata_freelist(&anim_data);
+
+  if (slots.size() == 0) {
+    WM_report(RPT_WARNING, "None of the selected channels is an Action Slot");
+    return OPERATOR_CANCELLED;
+  }
+
+  /* If multiple slots are selected they are moved to the new action together. In that case it is
+   * hard to determine a name, so a constant default is used. */
+  Action *target_action;
+  Main *bmain = CTX_data_main(C);
+  if (slots.size() == 1) {
+    char actname[MAX_ID_NAME - 2];
+    SNPRINTF(actname, DATA_("%sAction"), slots[0].first->name + 2);
+    target_action = &action_add(*bmain, actname);
+  }
+  else {
+    target_action = &action_add(*bmain, DATA_("CombinedAction"));
+  }
+
+  Layer &layer = target_action->layer_add(std::nullopt);
+  layer.strip_add(*target_action, Strip::Type::Keyframe);
+
+  for (std::pair<Slot *, bAction *> &slot_data : slots) {
+    Action &source_action = slot_data.second->wrap();
+    move_slot(*bmain, *slot_data.first, source_action, *target_action);
+    DEG_id_tag_update(&source_action.id, ID_RECALC_ANIMATION_NO_FLUSH);
+  }
+
+  DEG_id_tag_update(&target_action->id, ID_RECALC_ANIMATION_NO_FLUSH);
+  DEG_relations_tag_update(bmain);
+  WM_event_add_notifier(C, NC_ANIMATION | ND_NLA_ACTCHANGE | NA_EDITED, nullptr);
+
+  return OPERATOR_FINISHED;
+}
+
+static bool slot_channels_move_to_new_action_poll(bContext *C)
+{
+  SpaceAction *space_action = CTX_wm_space_action(C);
+  if (!space_action) {
+    return false;
+  }
+  if (!space_action->action) {
+    CTX_wm_operator_poll_msg_set(C, "No active action to operate on");
+    return false;
+  }
+  if (!space_action->action->wrap().is_action_layered()) {
+    CTX_wm_operator_poll_msg_set(C, "Active action is not layered");
+    return false;
+  }
+  return true;
+}
+
+static void ANIM_OT_slot_channels_move_to_new_action(wmOperatorType *ot)
+{
+  ot->name = "Move Slots to new Action";
+  ot->idname = "ANIM_OT_slot_channels_move_to_new_action";
+  ot->description = "Move the selected slots into a newly created action";
+
+  ot->exec = slot_channels_move_to_new_action_exec;
+  ot->poll = slot_channels_move_to_new_action_poll;
+
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+}
+
+#endif /* WITH_ANIM_BAKLAVA */
+
 /**
  *  Find a Graph Editor area and set the context arguments accordingly.
  */
@@ -5566,6 +5667,10 @@ void ED_operatortypes_animchannels()
   WM_operatortype_append(ANIM_OT_channels_ungroup);
 
   WM_operatortype_append(ANIM_OT_channels_bake);
+
+#ifdef WITH_ANIM_BAKLAVA
+  WM_operatortype_append(ANIM_OT_slot_channels_move_to_new_action);
+#endif
 }
 
 void ED_keymap_animchannels(wmKeyConfig *keyconf)