USER_DATA free user data function

How-to
1

Description

what to do do clean user data.

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

STM32H7 serie

What LVGL version are you using?

7.8.1 DEV

Question

is it important to implement to free user data function ( i dont use it now ).

What is the impact if i dont implement it ?

How should i do it if needed it ?

My custom data type is void* and i always pass the same struct to it

	struct param_s{
		float value; 
		int32_t valueInt;
		float asign; 
                lv_obj_t *myobj;
	};
2

The impact depends on what your user data is. If it’s being allocated from a heap, it’ll slowly continue using up memory as you create objects till memory runs out. In general, if it’s possible to free anything you are not using, do so.

3

so my user data type is void pointer.
And i pass a pointer to a static structure to it.

How should i clean it ?

4

If the structure is static (not allocated dynamically), there is no need to free it.

5

Here is structure i pass as pointer

struct param_s param{
float num1;
float num2;
}


struct data_t{
	 lv_obj_t * arc;
	 lv_obj_t * label;
	 lv_obj_t * labelVal;
	 struct param_s *param;
	 lv_obj_t * knob;
};

.
.
.
struct data_t myData;


lv_obj_set_user_data(pot_t->arc, (void*)&myData);