/**
 * @file lv_chart.c
 *
 */

/*********************
 *      INCLUDES
 *********************/
#include "lv_chart.h"
#if LV_USE_CHART != 0

#include "../lv_core/lv_debug.h"
#include "../lv_core/lv_refr.h"
#include "../lv_draw/lv_draw.h"
#include "../lv_misc/lv_math.h"
#include "../lv_themes/lv_theme.h"

/*********************
 *      DEFINES
 *********************/
#define LV_OBJX_NAME "lv_chart"

#define LV_CHART_YMIN_DEF 0
#define LV_CHART_YMAX_DEF 100
#define LV_CHART_HDIV_DEF 3
#define LV_CHART_VDIV_DEF 5
#define LV_CHART_PNUM_DEF 10
#define LV_CHART_AXIS_MAJOR_TICK_LEN_COE 1 / 15
#define LV_CHART_AXIS_MINOR_TICK_LEN_COE 2 / 3
#define LV_CHART_AXIS_PRIMARY_Y 1
#define LV_CHART_AXIS_SECONDARY_Y 0
#define LV_CHART_LABEL_ITERATOR_FORWARD 1
#define LV_CHART_LABEL_ITERATOR_REVERSE 0

/**********************
 *      TYPEDEFS
 **********************/

typedef struct {
    const char * list_start;
    const char * current_pos;
    uint8_t items_left;
    uint8_t is_reverse_iter;
} lv_chart_label_iterator_t;

/**********************
 *  STATIC PROTOTYPES
 **********************/
static lv_design_res_t lv_chart_design(lv_obj_t * chart, const lv_area_t * clip_area, lv_design_mode_t mode);
static lv_res_t lv_chart_signal(lv_obj_t * chart, lv_signal_t sign, void * param);
static lv_style_list_t * lv_chart_get_style(lv_obj_t * chart, uint8_t part);

static void draw_series_bg(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * mask);
static void draw_series_line(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * clip_area);
static void draw_series_column(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * clip_area);
static void draw_axes(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * mask);
static void invalidate_lines(lv_obj_t * chart, uint16_t i);
static void invalidate_columns(lv_obj_t * chart, uint16_t i);
static void get_series_area(lv_obj_t * chart, lv_area_t * series_area);
static void get_next_axis_label(lv_chart_label_iterator_t * iterator, char * buf);
static inline bool is_tick_with_label(uint8_t tick_num, lv_chart_axis_cfg_t * axis);
static lv_chart_label_iterator_t create_axis_label_iter(const char * list, uint8_t iterator_dir);

/**********************
 *  STATIC VARIABLES
 **********************/
static lv_design_cb_t ancestor_design;
static lv_signal_cb_t ancestor_signal;

/**********************
 *      MACROS
 **********************/

/**********************
 *   GLOBAL FUNCTIONS
 **********************/

/**
 * Create a chart background objects
 * @param par pointer to an object, it will be the parent of the new chart background
 * @param copy pointer to a chart background object, if not NULL then the new object will be copied
 * from it
 * @return pointer to the created chart background
 */
lv_obj_t * lv_chart_create(lv_obj_t * par, const lv_obj_t * copy)
{
    LV_LOG_TRACE("chart create started");

    /*Create the ancestor basic object*/
    lv_obj_t * chart = lv_obj_create(par, copy);
    LV_ASSERT_MEM(chart);
    if(chart == NULL) return NULL;

    /*Allocate the object type specific extended data*/
    lv_chart_ext_t * ext = lv_obj_allocate_ext_attr(chart, sizeof(lv_chart_ext_t));
    LV_ASSERT_MEM(ext);
    if(ext == NULL) {
        lv_obj_del(chart);
        return NULL;
    }

    lv_ll_init(&ext->series_ll, sizeof(lv_chart_series_t));

    ext->ymin                  = LV_CHART_YMIN_DEF;
    ext->ymax                  = LV_CHART_YMAX_DEF;
    ext->hdiv_cnt              = LV_CHART_HDIV_DEF;
    ext->vdiv_cnt              = LV_CHART_VDIV_DEF;
    ext->point_cnt             = LV_CHART_PNUM_DEF;
    ext->type                  = LV_CHART_TYPE_LINE;
    ext->update_mode           = LV_CHART_UPDATE_MODE_SHIFT;
    memset(&ext->x_axis, 0, sizeof(ext->x_axis));
    memset(&ext->y_axis, 0, sizeof(ext->y_axis));
    memset(&ext->secondary_y_axis, 0, sizeof(ext->secondary_y_axis));
    ext->x_axis.major_tick_len = LV_CHART_TICK_LENGTH_AUTO;
    ext->x_axis.minor_tick_len = LV_CHART_TICK_LENGTH_AUTO;
    ext->y_axis.major_tick_len = LV_CHART_TICK_LENGTH_AUTO;
    ext->y_axis.minor_tick_len = LV_CHART_TICK_LENGTH_AUTO;
    ext->secondary_y_axis.major_tick_len = LV_CHART_TICK_LENGTH_AUTO;
    ext->secondary_y_axis.minor_tick_len = LV_CHART_TICK_LENGTH_AUTO;


    lv_style_list_init(&ext->style_series_bg);
    lv_style_list_init(&ext->style_series);

    if(ancestor_design == NULL) ancestor_design = lv_obj_get_design_cb(chart);
    if(ancestor_signal == NULL) ancestor_signal = lv_obj_get_signal_cb(chart);

    lv_obj_set_signal_cb(chart, lv_chart_signal);
    lv_obj_set_design_cb(chart, lv_chart_design);

    /*Init the new chart background object*/
    if(copy == NULL) {
        lv_obj_set_size(chart, LV_DPI * 3, LV_DPI * 2);

        lv_theme_apply(chart, LV_THEME_CHART);

    }
    else {
        lv_chart_ext_t * ext_copy = lv_obj_get_ext_attr(copy);

        lv_style_list_copy(&ext->style_series, &ext_copy->style_series);
        lv_style_list_copy(&ext->style_series_bg, &ext_copy->style_series_bg);

        ext->type       = ext_copy->type;
        ext->ymin       = ext_copy->ymin;
        ext->ymax       = ext_copy->ymax;
        ext->hdiv_cnt   = ext_copy->hdiv_cnt;
        ext->vdiv_cnt   = ext_copy->vdiv_cnt;
        ext->point_cnt  = ext_copy->point_cnt;
        memcpy(&ext->x_axis, &ext_copy->x_axis, sizeof(lv_chart_axis_cfg_t));
        memcpy(&ext->y_axis, &ext_copy->y_axis, sizeof(lv_chart_axis_cfg_t));
        memcpy(&ext->secondary_y_axis, &ext_copy->secondary_y_axis, sizeof(lv_chart_axis_cfg_t));

        /*Refresh the style with new signal function*/
        lv_obj_refresh_style(chart);
    }

    LV_LOG_INFO("chart created");

    return chart;
}

/*======================
 * Add/remove functions
 *=====================*/

/**
 * Allocate and add a data series to the chart
 * @param chart pointer to a chart object
 * @param color color of the data series
 * @return pointer to the allocated data series
 */
lv_chart_series_t * lv_chart_add_series(lv_obj_t * chart, lv_color_t color)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext    = lv_obj_get_ext_attr(chart);
    lv_chart_series_t * ser = lv_ll_ins_head(&ext->series_ll);
    LV_ASSERT_MEM(ser);
    if(ser == NULL) return NULL;

    lv_coord_t def = LV_CHART_POINT_DEF;

    ser->color  = color;
    ser->points = lv_mem_alloc(sizeof(lv_coord_t) * ext->point_cnt);
    LV_ASSERT_MEM(ser->points);
    if(ser->points == NULL) {
        lv_ll_remove(&ext->series_ll, ser);
        lv_mem_free(ser);
        return NULL;
    }

    ser->start_point = 0;

    uint16_t i;
    lv_coord_t * p_tmp = ser->points;
    for(i = 0; i < ext->point_cnt; i++) {
        *p_tmp = def;
        p_tmp++;
    }

    return ser;
}

/**
 * Clear the point of a serie
 * @param chart pointer to a chart object
 * @param serie pointer to the chart's serie to clear
 */
void lv_chart_clear_serie(lv_obj_t * chart, lv_chart_series_t * serie)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
    LV_ASSERT_NULL(serie);

    if(chart == NULL || serie == NULL) return;
    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(ext == NULL) return;

    uint32_t i;
    for(i = 0; i < ext->point_cnt; i++) {
        serie->points[i] = LV_CHART_POINT_DEF;
    }

    serie->start_point = 0;
}

/*=====================
 * Setter functions
 *====================*/

/**
 * Set the number of horizontal and vertical division lines
 * @param chart pointer to a graph background object
 * @param hdiv number of horizontal division lines
 * @param vdiv number of vertical division lines
 */
void lv_chart_set_div_line_count(lv_obj_t * chart, uint8_t hdiv, uint8_t vdiv)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(ext->hdiv_cnt == hdiv && ext->vdiv_cnt == vdiv) return;

    ext->hdiv_cnt = hdiv;
    ext->vdiv_cnt = vdiv;

    lv_obj_invalidate(chart);
}

/**
 * Set the minimal and maximal y values
 * @param chart pointer to a graph background object
 * @param ymin y minimum value
 * @param ymax y maximum value
 */
void lv_chart_set_range(lv_obj_t * chart, lv_coord_t ymin, lv_coord_t ymax)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(ext->ymin == ymin && ext->ymax == ymax) return;

    ext->ymin = ymin;
    ext->ymax = ymax;

    lv_chart_refresh(chart);
}

/**
 * Set a new type for a chart
 * @param chart pointer to a chart object
 * @param type new type of the chart (from 'lv_chart_type_t' enum)
 */
void lv_chart_set_type(lv_obj_t * chart, lv_chart_type_t type)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(ext->type == type) return;

    ext->type = type;

    lv_chart_refresh(chart);
}

/**
 * Set the number of points on a data line on a chart
 * @param chart pointer r to chart object
 * @param point_cnt new number of points on the data lines
 */
void lv_chart_set_point_count(lv_obj_t * chart, uint16_t point_cnt)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(ext->point_cnt == point_cnt) return;

    lv_chart_series_t * ser;
    uint16_t point_cnt_old = ext->point_cnt;
    uint16_t i;
    lv_coord_t def = LV_CHART_POINT_DEF;

    if(point_cnt < 1) point_cnt = 1;

    LV_LL_READ_BACK(ext->series_ll, ser) {
        if(ser->start_point != 0) {
            lv_coord_t * new_points = lv_mem_alloc(sizeof(lv_coord_t) * point_cnt);
            LV_ASSERT_MEM(new_points);
            if(new_points == NULL) return;

            if(point_cnt >= point_cnt_old) {
                for(i = 0; i < point_cnt_old; i++) {
                    new_points[i] =
                        ser->points[(i + ser->start_point) % point_cnt_old]; /*Copy old contents to new array*/
                }
                for(i = point_cnt_old; i < point_cnt; i++) {
                    new_points[i] = def; /*Fill up the rest with default value*/
                }
            }
            else {
                for(i = 0; i < point_cnt; i++) {
                    new_points[i] =
                        ser->points[(i + ser->start_point) % point_cnt_old]; /*Copy old contents to new array*/
                }
            }

            /*Switch over pointer from old to new*/
            lv_mem_free(ser->points);
            ser->points = new_points;
        }
        else {
            ser->points = lv_mem_realloc(ser->points, sizeof(lv_coord_t) * point_cnt);
            LV_ASSERT_MEM(ser->points);
            if(ser->points == NULL) return;
            /*Initialize the new points*/
            if(point_cnt > point_cnt_old) {
                for(i = point_cnt_old - 1; i < point_cnt; i++) {
                    ser->points[i] = def;
                }
            }
        }

        ser->start_point = 0;
    }

    ext->point_cnt = point_cnt;

    lv_chart_refresh(chart);
}

/**
 * Initialize all data points with a value
 * @param chart pointer to chart object
 * @param ser pointer to a data series on 'chart'
 * @param y the new value  for all points
 */
void lv_chart_init_points(lv_obj_t * chart, lv_chart_series_t * ser, lv_coord_t y)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
    LV_ASSERT_NULL(ser);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    uint16_t i;
    for(i = 0; i < ext->point_cnt; i++) {
        ser->points[i] = y;
    }
    ser->start_point = 0;
    lv_chart_refresh(chart);
}

/**
 * Set the value of points from an array
 * @param chart pointer to chart object
 * @param ser pointer to a data series on 'chart'
 * @param y_array array of 'lv_coord_t' points (with 'points count' elements )
 */
void lv_chart_set_points(lv_obj_t * chart, lv_chart_series_t * ser, lv_coord_t y_array[])
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
    LV_ASSERT_NULL(ser);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    memcpy(ser->points, y_array, ext->point_cnt * (sizeof(lv_coord_t)));
    ser->start_point = 0;
    lv_chart_refresh(chart);
}

/**
 * Shift all data left and set the rightmost data on a data line
 * @param chart pointer to chart object
 * @param ser pointer to a data series on 'chart'
 * @param y the new value of the rightmost data
 */
void lv_chart_set_next(lv_obj_t * chart, lv_chart_series_t * ser, lv_coord_t y)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
    LV_ASSERT_NULL(ser);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(ext->update_mode == LV_CHART_UPDATE_MODE_SHIFT) {
        ser->points[ser->start_point] =
            y; /*This was the place of the former left most value, after shifting it is the rightmost*/
        ser->start_point = (ser->start_point + 1) % ext->point_cnt;
        lv_chart_refresh(chart);
    }
    else if(ext->update_mode == LV_CHART_UPDATE_MODE_CIRCULAR) {
        ser->points[ser->start_point] = y;

        if(ext->type & LV_CHART_TYPE_LINE) invalidate_lines(chart, ser->start_point);
        if(ext->type & LV_CHART_TYPE_COLUMN) invalidate_columns(chart, ser->start_point);

        ser->start_point = (ser->start_point + 1) % ext->point_cnt; /*update the x for next incoming y*/
    }
}

/**
 * Set update mode of the chart object.
 * @param chart pointer to a chart object
 * @param update mode
 */
void lv_chart_set_update_mode(lv_obj_t * chart, lv_chart_update_mode_t update_mode)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(ext->update_mode == update_mode) return;

    ext->update_mode = update_mode;
    lv_obj_invalidate(chart);
}

/**
 * Set the length of the tick marks on the x axis
 * @param chart pointer to the chart
 * @param major_tick_len the length of the major tick or `LV_CHART_TICK_LENGTH_AUTO` to set automatically
 *                       (where labels are added)
 * @param minor_tick_len the length of the minor tick, `LV_CHART_TICK_LENGTH_AUTO` to set automatically
 *                       (where no labels are added)
 */
void lv_chart_set_x_tick_length(lv_obj_t * chart, uint8_t major_tick_len, uint8_t minor_tick_len)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext       = lv_obj_get_ext_attr(chart);
    ext->x_axis.major_tick_len = major_tick_len;
    ext->x_axis.minor_tick_len = minor_tick_len;
}

/**
 * Set the length of the tick marks on the y axis
 * @param chart pointer to the chart
 * @param major_tick_len the length of the major tick or `LV_CHART_TICK_LENGTH_AUTO` to set automatically
 *                       (where labels are added)
 * @param minor_tick_len the length of the minor tick, `LV_CHART_TICK_LENGTH_AUTO` to set automatically
 *                       (where no labels are added)
 */
void lv_chart_set_y_tick_length(lv_obj_t * chart, uint8_t major_tick_len, uint8_t minor_tick_len)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext       = lv_obj_get_ext_attr(chart);
    ext->y_axis.major_tick_len = major_tick_len;
    ext->y_axis.minor_tick_len = minor_tick_len;
}

/**
 * Set the length of the tick marks on the secondary y axis
 * @param chart pointer to the chart
 * @param major_tick_len the length of the major tick or `LV_CHART_TICK_LENGTH_AUTO` to set automatically
 *                       (where labels are added)
 * @param minor_tick_len the length of the minor tick, `LV_CHART_TICK_LENGTH_AUTO` to set automatically
 *                       (where no labels are added)
 */
void lv_chart_set_secondary_y_tick_length(lv_obj_t * chart, uint8_t major_tick_len, uint8_t minor_tick_len)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext       = lv_obj_get_ext_attr(chart);
    ext->secondary_y_axis.major_tick_len = major_tick_len;
    ext->secondary_y_axis.minor_tick_len = minor_tick_len;
}

/**
 * Set the x-axis tick count and labels of a chart
 * @param chart             pointer to a chart object
 * @param list_of_values    list of string values, terminated with \n, except the last
 * @param num_tick_marks    if list_of_values is NULL: total number of ticks per axis
 *                          else number of ticks between two value labels
 * @param options           extra options
 */
void lv_chart_set_x_tick_texts(lv_obj_t * chart, const char * list_of_values, uint8_t num_tick_marks,
                               lv_chart_axis_options_t options)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
    LV_ASSERT_NULL(list_of_values);

    lv_chart_ext_t * ext       = lv_obj_get_ext_attr(chart);
    ext->x_axis.num_tick_marks = num_tick_marks;
    ext->x_axis.list_of_values = list_of_values;
    ext->x_axis.options        = options;
}

/**
 * Set the y-axis tick count and labels of a chart
 * @param chart             pointer to a chart object
 * @param list_of_values    list of string values, terminated with \n, except the last
 * @param num_tick_marks    if list_of_values is NULL: total number of ticks per axis
 *                          else number of ticks between two value labels
 * @param options           extra options
 */
void lv_chart_set_y_tick_texts(lv_obj_t * chart, const char * list_of_values, uint8_t num_tick_marks,
                               lv_chart_axis_options_t options)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
    LV_ASSERT_NULL(list_of_values);

    lv_chart_ext_t * ext       = lv_obj_get_ext_attr(chart);
    ext->y_axis.num_tick_marks = num_tick_marks;
    ext->y_axis.list_of_values = list_of_values;
    ext->y_axis.options        = options;
}

/**
 * Set the secondary y-axis tick count and labels of a chart
 * @param chart             pointer to a chart object
 * @param list_of_values    list of string values, terminated with \n, except the last
 * @param num_tick_marks    if list_of_values is NULL: total number of ticks per axis
 *                          else number of ticks between two value labels
 * @param options           extra options
 */
void lv_chart_set_secondary_y_tick_texts(lv_obj_t * chart, const char * list_of_values, uint8_t num_tick_marks,
                                         lv_chart_axis_options_t options)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);
    LV_ASSERT_NULL(list_of_values);

    lv_chart_ext_t * ext       = lv_obj_get_ext_attr(chart);
    ext->secondary_y_axis.num_tick_marks = num_tick_marks;
    ext->secondary_y_axis.list_of_values = list_of_values;
    ext->secondary_y_axis.options        = options;
}

/*=====================
 * Getter functions
 *====================*/

/**
 * Get the type of a chart
 * @param chart pointer to chart object
 * @return type of the chart (from 'lv_chart_t' enum)
 */
lv_chart_type_t lv_chart_get_type(const lv_obj_t * chart)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    return ext->type;
}

/**
 * Get the data point number per data line on chart
 * @param chart pointer to chart object
 * @return point number on each data line
 */
uint16_t lv_chart_get_point_count(const lv_obj_t * chart)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    return ext->point_cnt;
}

/*=====================
 * Other functions
 *====================*/

/**
 * Refresh a chart if its data line has changed
 * @param chart pointer to chart object
 */
void lv_chart_refresh(lv_obj_t * chart)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_obj_invalidate(chart);
}

/**********************
 *   STATIC FUNCTIONS
 **********************/

/**
 * Handle the drawing related tasks of the chart backgrounds
 * @param chart pointer to an object
 * @param clip_area the object will be drawn only in this area
 * @param mode LV_DESIGN_COVER_CHK: only check if the object fully covers the 'mask_p' area
 *                                  (return 'true' if yes)
 *             LV_DESIGN_DRAW: draw the object (always return 'true')
 *             LV_DESIGN_DRAW_POST: drawing after every children are drawn
 * @param return an element of `lv_design_res_t`
 */
static lv_design_res_t lv_chart_design(lv_obj_t * chart, const lv_area_t * clip_area, lv_design_mode_t mode)
{
    if(mode == LV_DESIGN_COVER_CHK) {
        return ancestor_design(chart, clip_area, mode);
    }
    else if(mode == LV_DESIGN_DRAW_MAIN) {
        /*Draw the background*/
        lv_draw_rect_dsc_t bg_dsc;
        lv_draw_rect_dsc_init(&bg_dsc);
        lv_obj_init_draw_rect_dsc(chart, LV_CHART_PART_BG, &bg_dsc);
        lv_draw_rect(&chart->coords, clip_area, &bg_dsc);

        lv_area_t series_area;
        get_series_area(chart, &series_area);

        draw_series_bg(chart, &series_area, clip_area);
        draw_axes(chart, &series_area, clip_area);


        lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
        if(ext->type & LV_CHART_TYPE_LINE) draw_series_line(chart, &series_area, clip_area);
        if(ext->type & LV_CHART_TYPE_COLUMN) draw_series_column(chart, &series_area, clip_area);

    }
    return LV_DESIGN_RES_OK;
}

/**
 * Signal function of the chart background
 * @param chart pointer to a chart background object
 * @param sign a signal type from lv_signal_t enum
 * @param param pointer to a signal specific variable
 */
static lv_res_t lv_chart_signal(lv_obj_t * chart, lv_signal_t sign, void * param)
{
    /* Include the ancient signal function */
    lv_res_t res;
    if(sign == LV_SIGNAL_GET_STYLE) {
        lv_get_style_info_t * info = param;
        info->result = lv_chart_get_style(chart, info->part);
        if(info->result != NULL) return LV_RES_OK;
        else return ancestor_signal(chart, sign, param);
    }

    res = ancestor_signal(chart, sign, param);
    if(res != LV_RES_OK) return res;
    if(sign == LV_SIGNAL_GET_TYPE) return lv_obj_handle_get_type_signal(param, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);

    if(sign == LV_SIGNAL_CLEANUP) {
        lv_coord_t ** datal;
        LV_LL_READ(ext->series_ll, datal) {
            lv_mem_free(*datal);
        }
        lv_ll_clear(&ext->series_ll);

        lv_obj_clean_style_list(chart, LV_CHART_PART_SERIES);
        lv_obj_clean_style_list(chart, LV_CHART_PART_SERIES_BG);
    }

    return res;
}


/**
 * Get the style descriptor of a part of the object
 * @param chart pointer the object
 * @param part the part of the chart. (LV_CHART_PART_...)
 * @return pointer to the style descriptor of the specified part
 */
static lv_style_list_t * lv_chart_get_style(lv_obj_t * chart, uint8_t part)
{
    LV_ASSERT_OBJ(chart, LV_OBJX_NAME);

    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    lv_style_list_t * style_dsc_p;

    switch(part) {
        case LV_CHART_PART_BG:
            style_dsc_p = &chart->style_list;
            break;
        case LV_CHART_PART_SERIES_BG:
            style_dsc_p = &ext->style_series_bg;
            break;
        case LV_CHART_PART_SERIES:
            style_dsc_p = &ext->style_series;
            break;
        default:
            style_dsc_p = NULL;
    }

    return style_dsc_p;
}

/**
 * Draw the division lines on chart background
 * @param chart pointer to chart object
 * @param clip_area mask, inherited from the design function
 */
static void draw_series_bg(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * clip_area)
{
    /*Draw the background of the series*/
    lv_draw_rect_dsc_t bg_dsc;
    lv_draw_rect_dsc_init(&bg_dsc);
    lv_obj_init_draw_rect_dsc(chart, LV_CHART_PART_SERIES_BG, &bg_dsc);
    lv_draw_rect(series_area, clip_area, &bg_dsc);

    lv_chart_ext_t * ext     = lv_obj_get_ext_attr(chart);

    uint8_t div_i;
    uint8_t div_i_end;
    uint8_t div_i_start;
    lv_point_t p1;
    lv_point_t p2;
    lv_coord_t w     = lv_area_get_width(series_area);
    lv_coord_t h     = lv_area_get_height(series_area);
    lv_coord_t x_ofs = series_area->x1;
    lv_coord_t y_ofs = series_area->y1;

    lv_draw_line_dsc_t line_dsc;
    lv_draw_line_dsc_init(&line_dsc);
    lv_obj_init_draw_line_dsc(chart, LV_CHART_PART_SERIES_BG, &line_dsc);

    if(ext->hdiv_cnt != 0) {
        /*Draw side lines if no border*/
        if(bg_dsc.border_width != 0) {
            div_i_start = 1;
            div_i_end   = ext->hdiv_cnt;
        }
        else {
            div_i_start = 0;
            div_i_end   = ext->hdiv_cnt + 1;
        }

        p1.x = 0 + x_ofs;
        p2.x = w - 1 + x_ofs;
        for(div_i = div_i_start; div_i <= div_i_end; div_i++) {
            p1.y = (int32_t)((int32_t)(h - line_dsc.width) * div_i) / (ext->hdiv_cnt + 1);
            p1.y += y_ofs;
            p2.y = p1.y;
            lv_draw_line(&p1, &p2, clip_area, &line_dsc);
        }
    }

    if(ext->vdiv_cnt != 0) {
        /*Draw side lines if no border*/
        if(bg_dsc.border_width != 0) {
            div_i_start = 1;
            div_i_end   = ext->vdiv_cnt;
        }
        else {
            div_i_start = 0;
            div_i_end   = ext->vdiv_cnt + 1;
        }

        p1.y = 0 + y_ofs;
        p2.y = h + y_ofs - 1;
        for(div_i = div_i_start; div_i <= div_i_end; div_i++) {
            p1.x = (int32_t)((int32_t)(w - line_dsc.width) * div_i) / (ext->vdiv_cnt + 1);
            p1.x += x_ofs;
            p2.x = p1.x;
            lv_draw_line(&p1, &p2, clip_area, &line_dsc);
        }
    }
}

/**
 * Draw the data lines as lines on a chart
 * @param obj pointer to chart object
 */
static void draw_series_line(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * clip_area)
{
    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);

    uint16_t i;
    lv_point_t p1;
    lv_point_t p2;
    lv_coord_t w     = lv_area_get_width(series_area);
    lv_coord_t h     = lv_area_get_height(series_area);
    lv_coord_t x_ofs = series_area->x1;
    lv_coord_t y_ofs = series_area->y1;
    lv_chart_series_t * ser;

    lv_area_t series_mask;
    bool mask_ret = lv_area_intersect(&series_mask, series_area, clip_area);
    if(mask_ret == false) return;

    lv_draw_line_dsc_t line_dsc;
    lv_draw_line_dsc_init(&line_dsc);
    lv_obj_init_draw_line_dsc(chart, LV_CHART_PART_SERIES, &line_dsc);

    lv_draw_mask_fade_param_t mask_fade_p;
    int16_t mask_fade_id = LV_MASK_ID_INV;
    lv_draw_rect_dsc_t area_dsc;
    bool has_area = lv_obj_get_style_bg_opa(chart, LV_CHART_PART_SERIES) > LV_OPA_MIN ? true : false;
    bool has_fade = false;
    if(has_area) {
        lv_draw_rect_dsc_init(&area_dsc);
        lv_obj_init_draw_rect_dsc(chart, LV_CHART_PART_SERIES, &area_dsc);

        has_fade = area_dsc.bg_grad_dir == LV_GRAD_DIR_VER ? true : false;
        if(has_fade) {
            lv_draw_mask_fade_init(&mask_fade_p, &chart->coords, area_dsc.bg_main_color_stop, chart->coords.y1,
                                   area_dsc.bg_grad_color_stop, chart->coords.y2);
        }
    }

    lv_draw_rect_dsc_t point_dsc;
    lv_draw_rect_dsc_init(&point_dsc);
    point_dsc.bg_opa = line_dsc.opa;
    point_dsc.radius = LV_RADIUS_CIRCLE;

    lv_coord_t point_radius = lv_obj_get_style_size(chart, LV_CHART_PART_SERIES);

    /*Go through all data lines*/
    LV_LL_READ_BACK(ext->series_ll, ser) {
        line_dsc.color = ser->color;
        point_dsc.bg_color = ser->color;
        area_dsc.bg_color = ser->color;
        area_dsc.bg_grad_color = ser->color;

        lv_coord_t start_point = ext->update_mode == LV_CHART_UPDATE_MODE_SHIFT ? ser->start_point : 0;

        p1.x = 0 + x_ofs;
        p2.x = 0 + x_ofs;

        lv_coord_t p_act = start_point;
        lv_coord_t p_prev = start_point;
        int32_t y_tmp = (int32_t)((int32_t)ser->points[p_prev] - ext->ymin) * h;
        y_tmp  = y_tmp / (ext->ymax - ext->ymin);
        p2.y   = h - y_tmp + y_ofs;

        for(i = 0; i < ext->point_cnt; i++) {
            p1.x = p2.x;
            p1.y = p2.y;

            p2.x = ((w * i) / (ext->point_cnt - 1)) + x_ofs;

            p_act = (start_point + i) % ext->point_cnt;

            y_tmp = (int32_t)((int32_t)ser->points[p_act] - ext->ymin) * h;
            y_tmp = y_tmp / (ext->ymax - ext->ymin);
            p2.y  = h - y_tmp + y_ofs;

            /*Don't draw the first point. A second point is also required to draw the line*/
            if(i != 0 && ser->points[p_prev] != LV_CHART_POINT_DEF && ser->points[p_act] != LV_CHART_POINT_DEF) {
                lv_draw_line(&p1, &p2, &series_mask, &line_dsc);

                lv_coord_t y_top = LV_MATH_MIN(p1.y, p2.y);
                if(has_area && y_top <= clip_area->y2) {
                    int16_t mask_line_id;
                    lv_draw_mask_line_param_t mask_line_p;
                    lv_draw_mask_line_points_init(&mask_line_p, p1.x, p1.y, p2.x, p2.y, LV_DRAW_MASK_LINE_SIDE_BOTTOM);
                    mask_line_id = lv_draw_mask_add(&mask_line_p, NULL);

                    lv_area_t a;
                    a.x1 = p1.x;
                    a.x2 = p2.x - 1;
                    a.y1 = y_top;
                    a.y2 = series_area->y2;

                    if(has_fade) mask_fade_id = lv_draw_mask_add(&mask_fade_p, NULL);

                    lv_draw_rect(&a, &series_mask, &area_dsc);

                    lv_draw_mask_remove_id(mask_line_id);
                    lv_draw_mask_remove_id(mask_fade_id);
                }
            }

            if(point_radius) {
                lv_area_t point_area;

                point_area.x1 = p1.x;
                point_area.x2 = point_area.x1 + point_radius;
                point_area.x1 -= point_radius;

                point_area.y1 = p1.y;
                point_area.y2 = point_area.y1 + point_radius;
                point_area.y1 -= point_radius;

                if(ser->points[p_act] != LV_CHART_POINT_DEF) {
                    /*Don't limit to `series_mask` to get full circles on the ends*/
                    lv_draw_rect(&point_area, &series_mask, &point_dsc);
                }
            }

            p_prev = p_act;
        }

        /*Draw the last point*/
        if(point_radius) {
            lv_area_t point_area;

            point_area.x1 = p2.x;
            point_area.x2 = point_area.x1 + point_radius;
            point_area.x1 -= point_radius;

            point_area.y1 = p2.y;
            point_area.y2 = point_area.y1 + point_radius;
            point_area.y1 -= point_radius;

            if(ser->points[p_act] != LV_CHART_POINT_DEF) {
                /*Don't limit to `series_mask` to get full circles on the ends*/
                lv_draw_rect(&point_area, clip_area, &point_dsc);
            }
        }
    }
}

/**
 * Draw the data lines as columns on a chart
 * @param chart pointer to chart object
 * @param mask mask, inherited from the design function
 */
static void draw_series_column(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * clip_area)
{
    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);

    uint16_t i;
    lv_area_t col_a;
    lv_coord_t w = lv_area_get_width(series_area);
    lv_coord_t h = lv_area_get_height(series_area);
    int32_t y_tmp;
    lv_chart_series_t * ser;
    lv_coord_t col_w = w / ((lv_ll_get_len(&ext->series_ll) + 1) * ext->point_cnt); /* Suppose + 1 series as separator*/
    lv_coord_t x_ofs = col_w / 2;                                    /*Shift with a half col.*/
    lv_style_int_t col_space = lv_obj_get_style_pad_inner(chart, LV_CHART_PART_SERIES);

    lv_draw_rect_dsc_t col_dsc;
    lv_draw_rect_dsc_init(&col_dsc);
    lv_obj_init_draw_rect_dsc(chart, LV_CHART_PART_SERIES, &col_dsc);
    col_dsc.bg_grad_dir = LV_GRAD_DIR_NONE;

    /*Make the cols longer with `radius` to clip the rounding from the bottom*/
    col_a.y2 = series_area->y2 + col_dsc.radius;

    lv_area_t series_mask;
    bool mask_ret = lv_area_intersect(&series_mask, series_area, clip_area);
    if(mask_ret == false) return;

    /*Go through all points*/
    for(i = 0; i < ext->point_cnt; i++) {
        lv_coord_t x_act = (int32_t)((int32_t)w * i) / ext->point_cnt;
        x_act += series_area->x1 + x_ofs;

        /*Draw the current point of all data line*/
        LV_LL_READ_BACK(ext->series_ll, ser) {
            lv_coord_t start_point = ext->update_mode == LV_CHART_UPDATE_MODE_SHIFT ? ser->start_point : 0;

            col_a.x1 = x_act;
            col_a.x2 = col_a.x1 + col_w - col_space;
            x_act += col_w;

            if(col_a.x2 < series_mask.x1) continue;
            if(col_a.x1 > series_mask.x2) break;

            col_dsc.bg_color = ser->color;

            lv_coord_t p_act = (start_point + i) % ext->point_cnt;
            y_tmp            = (int32_t)((int32_t)ser->points[p_act] - ext->ymin) * h;
            y_tmp            = y_tmp / (ext->ymax - ext->ymin);
            col_a.y1         = h - y_tmp + series_area->y1;

            if(ser->points[p_act] != LV_CHART_POINT_DEF) {
                lv_draw_rect(&col_a, &series_mask, &col_dsc);
            }
        }
    }
}

///**
// * Draw the data lines as vertical lines on a chart if there is only 1px between point
// * @param obj pointer to chart object
// */
//static void lv_chart_draw_vertical_lines(lv_obj_t * chart, const lv_area_t * mask)
//{
//
//    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
//    lv_coord_t w         = lv_obj_get_width(chart);
//    /*Vertical lines works only if the width == point count. Else use the normal line type*/
//    if(ext->point_cnt != w) {
//        lv_chart_draw_lines(chart, mask);
//        return;
//    }
//
//    uint16_t i;
//    lv_point_t p1;
//    lv_point_t p2;
//    lv_coord_t p_act;
//    lv_coord_t h     = lv_obj_get_height(chart);
//    lv_coord_t x_ofs = chart->coords.x1;
//    lv_coord_t y_ofs = chart->coords.y1;
//    int32_t y_tmp;
//    lv_chart_series_t * ser;
//    lv_opa_t opa_scale = lv_obj_get_opa_scale(chart);
//    lv_style_t style;
//    lv_style_copy(&style, &lv_style_plain);
//    style.line.opa   = ext->series.opa;
//    style.line.width = ext->series.width;
//
//    /*Go through all data lines*/
//    LV_LL_READ_BACK(ext->series_ll, ser)
//    {
//        lv_coord_t start_point = ext->update_mode == LV_CHART_UPDATE_MODE_SHIFT ? ser->start_point : 0;
//        style.line.color       = ser->color;
//
//        p1.x  = 0 + x_ofs;
//        p2.x  = 0 + x_ofs;
//        y_tmp = (int32_t)((int32_t)ser->points[0] - ext->ymin) * h;
//        y_tmp = y_tmp / (ext->ymax - ext->ymin);
//        p2.y  = h - y_tmp + y_ofs;
//        p1.y  = p2.y;
//
//        for(i = 0; i < ext->point_cnt; i++) {
//            p_act = (start_point + i) % ext->point_cnt;
//
//            y_tmp = (int32_t)((int32_t)ser->points[p_act] - ext->ymin) * h;
//            y_tmp = y_tmp / (ext->ymax - ext->ymin);
//            p2.y  = h - y_tmp + y_ofs;
//
//            if(p1.y == p2.y) {
//                p2.x++;
//            }
//
//            if(ser->points[p_act] != LV_CHART_POINT_DEF) {
//                lv_draw_line(&p1, &p2, mask, &style, opa_scale);
//            }
//
//            p2.x = ((w * p_act) / (ext->point_cnt - 1)) + x_ofs;
//            p1.x = p2.x;
//            p1.y = p2.y;
//        }
//    }
//}

/**
 * Create iterator for newline-separated list
 * @param list pointer to newline-separated labels list
 * @param iterator_dir LV_CHART_ITERATOR_FORWARD or LV_CHART_LABEL_ITERATOR_REVERSE
 * @return lv_chart_label_iterator_t
 */
static lv_chart_label_iterator_t create_axis_label_iter(const char * list, uint8_t iterator_dir)
{
    lv_chart_label_iterator_t iterator = {0};
    uint8_t j;

    iterator.list_start = list;

    /* count number of list items */
    for(j = 0; list[j] != '\0'; j++) {
        if(list[j] == '\n')
            iterator.items_left++;
    }

    if(iterator_dir == LV_CHART_LABEL_ITERATOR_FORWARD) {
        iterator.is_reverse_iter = 0;
        iterator.current_pos = list;
    }
    else {
        iterator.is_reverse_iter = 1;
        // -1 to skip '\0' at the end of the string
        iterator.current_pos = list + j - 1;
    }
    iterator.items_left++;
    return iterator;
}

/**
 * Get next label from iterator created by lv_chart_create_label_iter()
 * @param iterator iterator to get label from
 * @param[out] buf buffer to point next label to
 */
static void get_next_axis_label(lv_chart_label_iterator_t * iterator, char * buf)
{
    uint8_t label_len = 0;
    if(iterator->is_reverse_iter) {
        const char * label_start;
        /* count the length of the current label*/
        while((*iterator->current_pos != '\n') &&
              (iterator->current_pos != iterator->list_start)) {
            iterator->current_pos--;
            label_len++;
        }

        label_start = iterator->current_pos;

        if(*iterator->current_pos == '\n') {
            /* do not copy \n symbol, +1 to skip it*/
            label_start++;
            /* skip newline*/
            iterator->current_pos--;
        }
        else {
            /* it is last label in list (first one from the beginning )*/
            label_len++;
        }

        /* do not allow output buffer overflow */
        if(label_len > LV_CHART_AXIS_TICK_LABEL_MAX_LEN) {
            label_len = LV_CHART_AXIS_TICK_LABEL_MAX_LEN;
        }

        strncpy(buf, label_start, label_len);
    }
    else {
        /* search for tick string */
        while(iterator->current_pos[label_len] != '\n' &&
              iterator->current_pos[label_len] != '\0') {
            /* do not overflow the buffer, but move to the end of the current label */
            if(label_len < LV_CHART_AXIS_TICK_LABEL_MAX_LEN) {
                buf[label_len] = iterator->current_pos[label_len];
                label_len++;
            }
            else {
                label_len++;
            }
        }

        iterator->current_pos += label_len;

        /* do not allow output buffer overflow */
        if(label_len > LV_CHART_AXIS_TICK_LABEL_MAX_LEN) {
            label_len = LV_CHART_AXIS_TICK_LABEL_MAX_LEN;
        }

        if(*iterator->current_pos == '\n') iterator->current_pos++;
    }

    /* terminate the string */
    buf[label_len] = '\0';
}

/**
 * Check whether there should be a label next to tick with given
 * number
 * @param tick_num number of the tick to check
 * @param axis pointer to struct containing info on the axis
 * @return true if label should be located next to current tick
 */
static inline bool is_tick_with_label(uint8_t tick_num, lv_chart_axis_cfg_t * axis)
{
    return ((tick_num == 0) || ((tick_num % axis->num_tick_marks) == 0));
}

static void draw_y_ticks(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * mask, uint8_t which_axis)
{
    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    lv_chart_axis_cfg_t * y_axis = (which_axis == LV_CHART_AXIS_PRIMARY_Y) ?
                                   &ext->y_axis : &ext->secondary_y_axis;

    if(y_axis->list_of_values == NULL && y_axis->num_tick_marks == 0)  return;

    uint8_t i;
    uint8_t num_of_labels;
    uint8_t num_scale_ticks;
    int8_t major_tick_len, minor_tick_len;
    uint8_t iter_dir;

    lv_point_t p1;
    lv_point_t p2;
    lv_coord_t x_ofs;
    lv_chart_label_iterator_t iter;
    lv_coord_t y_ofs = series_area->y1;
    lv_coord_t h     = lv_area_get_height(series_area);
    lv_coord_t w     = lv_area_get_width(series_area);
    char buf[LV_CHART_AXIS_TICK_LABEL_MAX_LEN + 1]; /* up to N symbols per label + null terminator */

    /* chose correct side of the chart */
    if(which_axis == LV_CHART_AXIS_PRIMARY_Y)
        x_ofs = series_area->x1;
    else
        x_ofs = series_area->x2;

    /* calculate the size of tick marks */
    if(y_axis->major_tick_len == LV_CHART_TICK_LENGTH_AUTO)
        major_tick_len = (int32_t)w * LV_CHART_AXIS_MAJOR_TICK_LEN_COE;
    else
        major_tick_len = y_axis->major_tick_len;

    if(y_axis->minor_tick_len == LV_CHART_TICK_LENGTH_AUTO)
        minor_tick_len = major_tick_len * LV_CHART_AXIS_MINOR_TICK_LEN_COE;
    else
        minor_tick_len = y_axis->minor_tick_len;

    /* tick lines on secondary y axis are drawn in other direction*/
    if(which_axis == LV_CHART_AXIS_SECONDARY_Y) {
        major_tick_len *= -1;
        minor_tick_len *= -1;
    }

    iter_dir = (y_axis->options & LV_CHART_AXIS_INVERSE_LABELS_ORDER) ? LV_CHART_LABEL_ITERATOR_REVERSE :
               LV_CHART_LABEL_ITERATOR_FORWARD;
    iter = create_axis_label_iter(y_axis->list_of_values, iter_dir);

    /*determine the number of options */
    num_of_labels = iter.items_left;

    /* we can't have string labels without ticks step, set to 1 if not specified */
    if(y_axis->num_tick_marks == 0) y_axis->num_tick_marks = 1;

    /* calculate total number of ticks */
    if(num_of_labels < 2)
        num_scale_ticks = y_axis->num_tick_marks;
    else
        num_scale_ticks = (y_axis->num_tick_marks * (num_of_labels - 1));

    lv_style_int_t label_dist  = which_axis == LV_CHART_AXIS_PRIMARY_Y ?
                                 lv_obj_get_style_pad_left(chart, LV_CHART_PART_SERIES_BG)  : lv_obj_get_style_pad_right(chart, LV_CHART_PART_SERIES_BG);

    lv_draw_line_dsc_t line_dsc;
    lv_draw_line_dsc_init(&line_dsc);
    lv_obj_init_draw_line_dsc(chart, LV_CHART_PART_BG, &line_dsc);

    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    lv_obj_init_draw_label_dsc(chart, LV_CHART_PART_BG, &label_dsc);

    for(i = 0; i < (num_scale_ticks + 1); i++) { /* one extra loop - it may not exist in the list, empty label */
        /* first point of the tick */
        p1.x = x_ofs;

        /* move extra pixel out of chart boundary */
        if(which_axis == LV_CHART_AXIS_PRIMARY_Y)
            p1.x--;
        else
            p1.x++;

        /* second point of the tick */
        if((num_of_labels != 0) && (i == 0 || i % y_axis->num_tick_marks == 0))
            p2.x = p1.x - major_tick_len; /* major tick */
        else
            p2.x = p1.x - minor_tick_len; /* minor tick */

        /* draw a line at moving y position */
        p2.y = p1.y =
                   y_ofs + (int32_t)((int32_t)(h - line_dsc.width) * i) / num_scale_ticks;

        if(y_axis->options & LV_CHART_AXIS_INVERSE_LABELS_ORDER) {
            /*if label order is inversed last tick have number 0*/
            if(i != 0)
                lv_draw_line(&p1, &p2, mask, &line_dsc);
            else if((y_axis->options & LV_CHART_AXIS_DRAW_LAST_TICK) != 0)
                lv_draw_line(&p1, &p2, mask, &line_dsc);
        }
        else {
            if(i != num_scale_ticks)
                lv_draw_line(&p1, &p2, mask, &line_dsc);
            else if((y_axis->options & LV_CHART_AXIS_DRAW_LAST_TICK) != 0)
                lv_draw_line(&p1, &p2, mask, &line_dsc);
        }

        /* draw values if available */
        if(num_of_labels != 0) {
            /* add text only to major tick */
            if(is_tick_with_label(i, y_axis)) {

                get_next_axis_label(&iter, buf);

                /* reserve appropriate area */
                lv_point_t size;
                lv_txt_get_size(&size, buf, label_dsc.font, label_dsc.letter_space, label_dsc.line_space,
                                LV_COORD_MAX, LV_TXT_FLAG_CENTER);

                /* set the area at some distance of the major tick len left of the tick */
                lv_area_t a = {.y1 = p2.y - size.y / 2, .y2 = p2.y + size.y / 2};

                if(which_axis == LV_CHART_AXIS_PRIMARY_Y) {
                    a.x1 = p2.x - size.x - label_dist;
                    a.x2 = p2.x - label_dist;
                }
                else {
                    a.x1 = p2.x + label_dist;
                    a.x2 = p2.x + size.x + label_dist;
                }

                lv_draw_label(&a, mask, &label_dsc, buf, NULL);
            }
        }
    }
}

static void draw_x_ticks(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * mask)
{
    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);

    if(ext->x_axis.list_of_values == NULL && ext->x_axis.num_tick_marks == 0) return;

    uint8_t i;
    uint8_t num_of_labels;
    uint8_t num_scale_ticks;
    uint8_t major_tick_len, minor_tick_len;
    lv_chart_label_iterator_t iter;
    lv_point_t p1;
    lv_point_t p2;
    lv_coord_t x_ofs = series_area->x1;
    lv_coord_t y_ofs = series_area->y1;
    lv_coord_t h     = lv_area_get_height(series_area);
    lv_coord_t w     = lv_area_get_width(series_area);
    char buf[LV_CHART_AXIS_TICK_LABEL_MAX_LEN + 1]; /* up to N symbols per label + null terminator */

    /* calculate the size of tick marks */
    if(ext->x_axis.major_tick_len == LV_CHART_TICK_LENGTH_AUTO)
        major_tick_len = (int32_t)w * LV_CHART_AXIS_MAJOR_TICK_LEN_COE;
    else
        major_tick_len = ext->x_axis.major_tick_len;

    if(ext->x_axis.minor_tick_len == LV_CHART_TICK_LENGTH_AUTO)
        minor_tick_len = major_tick_len * LV_CHART_AXIS_MINOR_TICK_LEN_COE;
    else
        minor_tick_len = ext->x_axis.minor_tick_len;

    /*determine the number of options */
    iter = create_axis_label_iter(ext->x_axis.list_of_values, LV_CHART_LABEL_ITERATOR_FORWARD);
    num_of_labels = iter.items_left;

    /* we can't have string labels without ticks step, set to 1 if not specified */
    if(ext->x_axis.num_tick_marks == 0) ext->x_axis.num_tick_marks = 1;

    /* calculate total number of marks */
    if(num_of_labels < 2)
        num_scale_ticks = ext->x_axis.num_tick_marks;
    else
        num_scale_ticks = (ext->x_axis.num_tick_marks * (num_of_labels - 1));


    lv_style_int_t label_dist  = lv_obj_get_style_pad_bottom(chart, LV_CHART_PART_SERIES_BG);

    lv_draw_line_dsc_t line_dsc;
    lv_draw_line_dsc_init(&line_dsc);
    lv_obj_init_draw_line_dsc(chart, LV_CHART_PART_BG, &line_dsc);

    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    lv_obj_init_draw_label_dsc(chart, LV_CHART_PART_BG, &label_dsc);

    for(i = 0; i < (num_scale_ticks + 1); i++) { /* one extra loop - it may not exist in the list, empty label */
        /* first point of the tick */
        p1.y = h + y_ofs;

        /* second point of the tick */
        if((num_of_labels != 0) && (i == 0 || i % ext->x_axis.num_tick_marks == 0))
            p2.y = p1.y + major_tick_len; /* major tick */
        else
            p2.y = p1.y + minor_tick_len; /* minor tick */

        /* draw a line at moving x position */
        p2.x = p1.x = x_ofs + (int32_t)((int32_t)(w - line_dsc.width) * i) / num_scale_ticks;

        if(i != num_scale_ticks)
            lv_draw_line(&p1, &p2, mask, &line_dsc);
        else if((ext->x_axis.options & LV_CHART_AXIS_DRAW_LAST_TICK) != 0)
            lv_draw_line(&p1, &p2, mask, &line_dsc);

        /* draw values if available */
        if(num_of_labels != 0) {
            /* add text only to major tick */
            if(is_tick_with_label(i, &(ext->x_axis))) {
                get_next_axis_label(&iter, buf);

                /* reserve appropriate area */
                lv_point_t size;
                lv_txt_get_size(&size, buf, label_dsc.font, label_dsc.letter_space, label_dsc.line_space,
                                LV_COORD_MAX, LV_TXT_FLAG_CENTER);

                /* set the area at some distance of the major tick len under of the tick */
                lv_area_t a = {(p2.x - size.x / 2), (p2.y + label_dist), (p2.x + size.x / 2),
                               (p2.y + size.y + label_dist)
                              };
                lv_draw_label(&a, mask, &label_dsc, buf, NULL);
            }
        }
    }
}

static void draw_axes(lv_obj_t * chart, const lv_area_t * series_area, const lv_area_t * mask)
{
    draw_y_ticks(chart, series_area, mask, LV_CHART_AXIS_PRIMARY_Y);
    draw_y_ticks(chart, series_area, mask, LV_CHART_AXIS_SECONDARY_Y);
    draw_x_ticks(chart, series_area, mask);
}

/**
 * invalid area of the new line data lines on a chart
 * @param obj pointer to chart object
 */
static void invalidate_lines(lv_obj_t * chart, uint16_t i)
{
    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);
    if(i >= ext->point_cnt) return;

    lv_area_t series_area;
    get_series_area(chart, &series_area);

    lv_coord_t w     = lv_area_get_width(&series_area);
    lv_coord_t x_ofs = series_area.x1;

    lv_style_int_t line_width = lv_obj_get_style_line_width(chart, LV_CHART_PART_SERIES);
    lv_style_int_t point_radius = lv_obj_get_style_size(chart, LV_CHART_PART_SERIES);

    lv_area_t coords;
    lv_area_copy(&coords, &series_area);
    if(i < ext->point_cnt - 1) {
        coords.x1 = ((w * i) / (ext->point_cnt - 1)) + x_ofs - line_width - point_radius;
        coords.x2 = ((w * (i + 1)) / (ext->point_cnt - 1)) + x_ofs + line_width + point_radius;
        lv_obj_invalidate_area(chart, &coords);
    }

    if(i > 0) {
        coords.x1 = ((w * (i - 1)) / (ext->point_cnt - 1)) + x_ofs - line_width - point_radius;
        coords.x2 = ((w * i) / (ext->point_cnt - 1)) + x_ofs + line_width + point_radius;
        lv_obj_invalidate_area(chart, &coords);
    }
}


/**
 * invalid area of the new column data lines on a chart
 * @param chart pointer to chart object
 * @param mask mask, inherited from the design function
 */
static void invalidate_columns(lv_obj_t * chart, uint16_t i)
{
    lv_chart_ext_t * ext = lv_obj_get_ext_attr(chart);

    lv_area_t series_area;
    get_series_area(chart, &series_area);

    lv_area_t col_a;
    lv_coord_t w     = lv_area_get_width(&series_area);
    lv_coord_t col_w = w / ((lv_ll_get_len(&ext->series_ll) + 1) * ext->point_cnt); /* Suppose + 1 series as separator*/
    lv_coord_t x_ofs = col_w / 2;                                    /*Shift with a half col.*/

    lv_coord_t x_act;
    x_act = (int32_t)((int32_t)w * i) / ext->point_cnt;
    x_act += series_area.x1 + x_ofs;

    lv_obj_get_coords(chart, &col_a);
    col_a.x1 = x_act;
    col_a.x2 = col_a.x1 + col_w;

    lv_inv_area(lv_obj_get_disp(chart), &col_a);
}

static void get_series_area(lv_obj_t * chart, lv_area_t * series_area)
{
    lv_area_copy(series_area, &chart->coords);
    series_area->x1 += lv_obj_get_style_pad_left(chart, LV_CHART_PART_BG);
    series_area->x2 -= lv_obj_get_style_pad_right(chart, LV_CHART_PART_BG);
    series_area->y1 += lv_obj_get_style_pad_top(chart, LV_CHART_PART_BG);
    series_area->y2 -= lv_obj_get_style_pad_bottom(chart, LV_CHART_PART_BG);
}

#endif