#include <Elementary.h>
typedef struct
{
   Eina_List *transitions;
   Evas_Object *box;
   Evas_Object_Box_Layout last_layout;
} Transitions_Data;
static void
_add_cb(void *data, Evas_Object *obj, void *ev)
{
   Evas_Object *btn;
   Eina_List *children;
   Transitions_Data *tdata = data;
   elm_object_text_set(btn, "I do nothing");
   if (children)
     {
        eina_list_free(children);
     }
   else
   evas_object_show(btn);
}
static void
_clear_cb(void *data, Evas_Object *obj, void *ev)
{
   Transitions_Data *tdata = data;
}
static void
_unpack_cb(void *data, Evas_Object *obj, void *ev)
{
   Transitions_Data *tdata = data;
   evas_object_move(obj, 0, 50);
   evas_object_color_set(obj, 128, 64, 0, 128);
}
static void
_test_box_transition_change(void *data)
{
   Transitions_Data *tdata = data;
   Evas_Object_Box_Layout next_layout;
   if (!data) return;
   next_layout = eina_list_data_get(tdata->transitions);
                                        NULL, NULL, next_layout, NULL, NULL,
                                        _test_box_transition_change, tdata);
   tdata->last_layout = next_layout;
   tdata->transitions = eina_list_demote_list(tdata->transitions,
                                              tdata->transitions);
}
EAPI_MAIN int
elm_main(int argc, char *argv[])
{
   Evas_Object *win, *bigbox, *bx, *bt;
   static Transitions_Data tdata = {
        .transitions = NULL,
        .box = NULL,
        .last_layout = NULL
   };
   evas_object_size_hint_weight_set(bigbox, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
   evas_object_show(bigbox);
   evas_object_show(bx);
   elm_object_text_set(bt, "Add");
   evas_object_show(bt);
   evas_object_smart_callback_add(bt, "clicked", _add_cb, &tdata);
   elm_object_text_set(bt, "Clear");
   evas_object_show(bt);
   evas_object_smart_callback_add(bt, "clicked", _clear_cb, &tdata);
   evas_object_size_hint_weight_set(bx, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
   evas_object_size_hint_align_set(bx, EVAS_HINT_FILL, EVAS_HINT_FILL);
   evas_object_show(bx);
   elm_object_text_set(bt, "Button 1");
   evas_object_smart_callback_add(bt, "clicked", _unpack_cb, &tdata);
   evas_object_size_hint_weight_set(bt, EVAS_HINT_EXPAND, EVAS_HINT_EXPAND);
   evas_object_size_hint_align_set(bt, EVAS_HINT_FILL, EVAS_HINT_FILL);
   evas_object_show(bt);
   elm_object_text_set(bt, "Button 2");
   evas_object_size_hint_weight_set(bt, EVAS_HINT_EXPAND, 0.0);
   evas_object_size_hint_align_set(bt, 1.0, 0.5);
   evas_object_smart_callback_add(bt, "clicked", _unpack_cb, &tdata);
   evas_object_show(bt);
   elm_object_text_set(bt, "Button 3");
   evas_object_smart_callback_add(bt, "clicked", _unpack_cb, &tdata);
   evas_object_show(bt);
   tdata.box = bx;
   tdata.last_layout = evas_object_box_layout_horizontal;
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_vertical);
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_horizontal);
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_stack);
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_homogeneous_vertical);
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_homogeneous_horizontal);
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_flow_vertical);
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_flow_horizontal);
   tdata.transitions = eina_list_append(tdata.transitions,
                                        evas_object_box_layout_stack);
   _test_box_transition_change(&tdata);
   evas_object_resize(win, 300, 320);
   evas_object_show(win);
   return 0;
}