efl_ui_focus_object: introduce prepare_logical

with this call a registered logical item could prepare itself for a
deeper traversal

src/lib/elementary/efl_ui_focus_manager_calc.c

@@ -1035,6 +1035,10 @@ _prev_item(Node *node)
    Eina_List *lnode;
 
    parent = T(node).parent;
+
+   //we are accessing the parents children, prepare!
+   efl_ui_focus_object_prepare_logical(parent->focusable);
+
    lnode = eina_list_data_find_list(T(parent).children, node);
    lnode = eina_list_prev(lnode);
 
@@ -1048,6 +1052,9 @@ _next(Node *node)
 {
    Node *n;
 
+   //prepare the node itself so if there are probebly no children, then they are here.
+   efl_ui_focus_object_prepare_logical(node->focusable);
+
    //Case 1 we are having children
    //But only enter the children if it does NOT have a redirect manager
    if (T(node).children && !node->redirect_manager)
@@ -1069,6 +1076,10 @@ _next(Node *node)
         Eina_List *lnode;
 
         parent = T(n).parent;
+
+        //we are accessing the parents children, prepare!
+        efl_ui_focus_object_prepare_logical(parent->focusable);
+
         lnode = eina_list_data_find_list(T(parent).children, n);
         lnode = eina_list_next(lnode);
 
@@ -1094,6 +1105,11 @@ _prev(Node *node)
      return NULL;
 
    n =_prev_item(node);
+
+   //we are accessing prev items children, prepare them!
+   if (n && n->focusable)
+     efl_ui_focus_object_prepare_logical(n->focusable);
+
    //case 1 there is a item in the parent previous to node, which has children
    if (n && T(n).children)
      {
@@ -1232,6 +1248,7 @@ _efl_ui_focus_manager_calc_efl_ui_focus_manager_focus_set(Eo *obj, Efl_Ui_Focus_
         F_DBG(" %p is logical, fetching the next subnode that is either a redirect or a regular", obj);
 
         //important! if there are no children _next would return the parent of node which will exceed the limit of children of node
+        efl_ui_focus_object_prepare_logical(node->focusable);
         if (node->tree.children)
           {
              target = node;
@@ -1240,7 +1257,6 @@ _efl_ui_focus_manager_calc_efl_ui_focus_manager_focus_set(Eo *obj, Efl_Ui_Focus_
              while (target && target->type == NODE_TYPE_ONLY_LOGICAL && !target->redirect_manager)
                {
                   target = _next(target);
-
                   //abort if we are exceeding the childrens of node
                   if (target == node) target = NULL;
                }
@@ -1470,6 +1486,10 @@ _efl_ui_focus_manager_calc_efl_ui_focus_manager_fetch(Eo *obj, Efl_Ui_Focus_Mana
 
    dirty_flush(obj, pd, n);
 
+   //make sure to prepare_logical so next and prev are correctly
+   if (n->tree.parent)
+     efl_ui_focus_object_prepare_logical(n->tree.parent->focusable);
+
 #define DIR_CLONE(dir) _convert(DIRECTION_ACCESS(n,dir).partners);
 
    res->right = DIR_CLONE(EFL_UI_FOCUS_DIRECTION_RIGHT);

src/lib/elementary/efl_ui_focus_object.eo

@@ -30,9 +30,16 @@ mixin Efl.Ui.Focus.Object
                 focus : bool; [[The state in which the object should be put]]
             }
         }
+        prepare_logical {
+            [[Tells the object that the children of it will be queried soon by the given manager.
+
+              Deleting items in the manager in this call will result in undefied behaviour and may crash. Dont do that!
+            ]]
+        }
     }
     implements {
         @empty .focus_geometry;
+        @empty .prepare_logical;
     }
     events {
         focus,changed : bool; [[Emitted if the focus state has changed]]