lvgl/examples/widgets/textarea/lv_example_textarea_1.c

#include "../../lv_examples.h"
#if LV_USE_TEXTAREA && LV_BUILD_EXAMPLES

static void textarea_event_handler(lv_event_t * e)
{
    lv_obj_t * ta = lv_event_get_target(e);
    LV_UNUSED(ta);
    LV_LOG_USER("Enter was pressed. The current text is: %s", lv_textarea_get_text(ta));
}

static void btnm_event_handler(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    lv_obj_t * ta = lv_event_get_user_data(e);
    const char * txt = lv_buttonmatrix_get_button_text(obj, lv_buttonmatrix_get_selected_button(obj));

    if(strcmp(txt, LV_SYMBOL_BACKSPACE) == 0) lv_textarea_delete_char(ta);
    else if(strcmp(txt, LV_SYMBOL_NEW_LINE) == 0) lv_obj_send_event(ta, LV_EVENT_READY, NULL);
    else lv_textarea_add_text(ta, txt);

}

void lv_example_textarea_1(void)
{
    lv_obj_t * ta = lv_textarea_create(lv_screen_active());
    lv_textarea_set_one_line(ta, true);
    lv_obj_align(ta, LV_ALIGN_TOP_MID, 0, 10);
    lv_obj_add_event_cb(ta, textarea_event_handler, LV_EVENT_READY, ta);
    lv_obj_add_state(ta, LV_STATE_FOCUSED); /*To be sure the cursor is visible*/

    static const char * btnm_map[] = {"1", "2", "3", "\n",
                                      "4", "5", "6", "\n",
                                      "7", "8", "9", "\n",
                                      LV_SYMBOL_BACKSPACE, "0", LV_SYMBOL_NEW_LINE, ""
                                     };

    lv_obj_t * btnm = lv_buttonmatrix_create(lv_screen_active());
    lv_obj_set_size(btnm, 200, 150);
    lv_obj_align(btnm, LV_ALIGN_BOTTOM_MID, 0, -10);
    lv_obj_add_event_cb(btnm, btnm_event_handler, LV_EVENT_VALUE_CHANGED, ta);
    lv_obj_remove_flag(btnm, LV_OBJ_FLAG_CLICK_FOCUSABLE); /*To keep the text area focused on button clicks*/
    lv_buttonmatrix_set_map(btnm, btnm_map);
}

#endif