How to change list's element?

How-to
1

Hello!
I would like to change dinamically icons on the buttons which are on the lv_list.
I create buttons like it is written in documentation

lv_list_add_btn(list1, LV_ICON_CALL, "kot3");

And I am not able to change the icon because there are only 4 functions for list widget: lv_list_create, lv_list_add_text, lv_list_add_btn and lv_list_get_btn_text
So, I decided to re-create the button (find the button with text “kot3”, remove it and create again with another icon).
So, the code is:

    uint32_t i;
    for(i = 0; i < lv_obj_get_child_cnt(list1); i++) {
      lv_obj_t * child = lv_obj_get_child(list1, i);
      char * s = (char*)lv_list_get_btn_text(list1, child);
      Serial.println(s);
      if (!strcmp(s, "kot3")){
          lv_obj_del(child);
          lv_obj_t * btn;
          btn = lv_list_add_btn(list1, LV_SYMBOL_EYE_OPEN, s);         // I also tried (const char*)s
      };

But now I see kot3 in serial and hT?ht?dp? on the screen

I also think that the icon is the first child of the element and I should re-create it and move background. Is it right?

What MCU/Processor/Board and compiler are you using?

Arduino IDE + ESP32 + LCD display

What LVGL version are you using?

8.3

Screenshot and/or video

later…

2

Yes! The problem was solved. Finally, I did it!
I have “list1” widget with buttons inside and to change button’s icon I wrote a simple function:

void change_icon(const char* username, const char * icon){
    uint32_t i;           // maybe type 'byte' because there are a few buttons...
    for(i = 0; i < lv_obj_get_child_cnt(list1); i++) {
        lv_obj_t * child = lv_obj_get_child(list1, i);
        char * s = (char*)lv_list_get_btn_text(list1, child);
        if (!strcmp(s, username)){
            lv_obj_t * label_icon = lv_obj_get_child(child, 0);
            lv_label_set_text(label_icon, icon);
        };
    }
}

To use it you need just type something like that

change_icon("kot-obormot", LV_SYMBOL_TRASH);

[kisvegabor], what about adding a new function like ‘lv_list_change_icon’ ?