lv_example_menu_2.c

#include "../../lv_examples.h"
#if LV_USE_MENU && LV_USE_MSGBOX && LV_BUILD_EXAMPLES

static void back_event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_obj_t * menu = lv_event_get_user_data(e);

    if(lv_menu_back_btn_is_root(menu, obj)) {
        lv_obj_t * mbox1 = lv_msgbox_create(NULL, "Hello", "Root back btn click.", NULL, true);
        lv_obj_center(mbox1);
    }
}

void lv_example_menu_2(void)
{
    lv_obj_t * menu = lv_menu_create(lv_scr_act());
    lv_menu_set_mode_root_back_btn(menu, LV_MENU_ROOT_BACK_BTN_ENABLED);
    lv_obj_add_event_cb(menu, back_event_handler, LV_EVENT_CLICKED, menu);
    lv_obj_set_size(menu, lv_disp_get_hor_res(NULL), lv_disp_get_ver_res(NULL));
    lv_obj_center(menu);

    lv_obj_t * cont;
    lv_obj_t * label;

    /*Create a sub page*/
    lv_obj_t * sub_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(sub_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Hello, I am hiding here");

    /*Create a main page*/
    lv_obj_t * main_page = lv_menu_page_create(menu, NULL);

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 1");

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 2");

    cont = lv_menu_cont_create(main_page);
    label = lv_label_create(cont);
    lv_label_set_text(label, "Item 3 (Click me!)");
    lv_menu_set_load_page_event(menu, cont, sub_page);

    lv_menu_set_page(menu, main_page);
}

#endif