drop down list for little vGL

• 下拉回調函數處理

  
  static void drop_down_list_event_handler(lv_obj_t* obj, lv_event_t event)
  {
      if (event == LV_EVENT_VALUE_CHANGED)
      {
          char buf[32];
          lv_ddlist_get_selected_str(obj, buf, sizeof(buf));
          printf("option: %s\n", buf);
      }
  }

• 下拉列表實現

  void drop_down_list_demo(void)
  {
      lv_obj_t* ddlist = lv_ddlist_create(lv_scr_act(), NULL);
      lv_ddlist_set_options(ddlist, "Apple\n"
          "Banana\n"
          "Orange\n"
          "Melon\n"
          "Grape\n"
          "Raspberry"
      );
  
      lv_ddlist_set_fix_width(ddlist, 150);
      lv_ddlist_set_draw_arrow(ddlist, true);
      lv_obj_align(ddlist, NULL, LV_ALIGN_IN_TOP_LEFT, 20, 20);
      lv_obj_set_event_cb(ddlist, drop_down_list_event_handler);
  
  
      //drop up list
  
      ddlist = lv_ddlist_create(lv_scr_act(), NULL);
      lv_ddlist_set_options(ddlist, "Apple2\n"
          "Banana2\n"
          "Orange2\n"
          "Melon2\n"
          "Grape2\n"
          "Raspberry2"
      );
      lv_ddlist_set_fix_width(ddlist, 150);
      lv_ddlist_set_fix_height(ddlist, 150);
      lv_ddlist_set_draw_arrow(ddlist, true);
      lv_obj_set_auto_realign(ddlist, true);
      lv_obj_align(ddlist, NULL, LV_ALIGN_IN_BOTTOM_MID, 0, -20);
  
      lv_obj_set_event_cb(ddlist, drop_down_list_event_handler);
  
  
  }

• 調用drop_down_list_demo函數，編譯運行