lvgl/examples/scroll/lv_example_scroll_8.c

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


/*
 * Circular list implementation based on:
 * Reference: https://blog.csdn.net/TQW4321/article/details/145434819
 */

/* Applies to both width (for row items) and height (for column items) */
#define ITEM_SIZE     80

/* Function to calculate the total content width of the container */
static int32_t get_content_width(lv_obj_t * cont)
{
    int32_t w = 0;
    int32_t pad_column = lv_obj_get_style_pad_column(cont, LV_PART_MAIN);
    int32_t total = (int32_t)lv_obj_get_child_count(cont);

    for(int32_t i = 0; i < total; i++) {
        w += lv_obj_get_width(lv_obj_get_child(cont, i));
        if(i < total - 1) w += pad_column;
    }
    return w + lv_obj_get_style_pad_left(cont, LV_PART_MAIN)
           + lv_obj_get_style_pad_right(cont, LV_PART_MAIN);
}

/* Scroll event callback for row layout */
static void cont_row_scroll_event_cb(lv_event_t * e)
{
    static bool is_adjusting = false;
    lv_obj_t * cont = lv_event_get_current_target_obj(e);

    if(!is_adjusting) {
        is_adjusting = true;
        int32_t scroll_x = lv_obj_get_scroll_x(cont);
        int32_t cont_w = lv_obj_get_width(cont);
        int32_t content_w = get_content_width(cont);

        /* Use ITEM_SIZE as horizontal item width */
        const int32_t item_width = ITEM_SIZE;

        if(scroll_x <= 0) {
            lv_obj_t * last_child = lv_obj_get_child(cont, (int32_t)(lv_obj_get_child_count(cont) - 1));
            lv_obj_move_to_index(last_child, 0);
            lv_obj_scroll_to_x(cont, scroll_x + item_width, LV_ANIM_OFF);
        }
        else if(scroll_x > content_w - cont_w) {
            lv_obj_t * first_child = lv_obj_get_child(cont, 0);
            lv_obj_move_to_index(first_child, (int32_t)(lv_obj_get_child_count(cont) - 1));
            lv_obj_scroll_to_x(cont, scroll_x - item_width, LV_ANIM_OFF);
        }
        is_adjusting = false;
    }
}

/* Function to calculate the total content height of the container */
static int32_t get_content_height(lv_obj_t * cont)
{
    int32_t h = 0;
    int32_t pad_row = lv_obj_get_style_pad_row(cont, LV_PART_MAIN);
    int32_t total = (int32_t)lv_obj_get_child_count(cont);

    for(int i = 0; i < total; i++) {
        h += lv_obj_get_height(lv_obj_get_child(cont, i));
        if(i < total - 1) h += pad_row;
    }
    return h + lv_obj_get_style_pad_top(cont, LV_PART_MAIN)
           + lv_obj_get_style_pad_bottom(cont, LV_PART_MAIN);
}

/* Scroll event callback for column layout */
static void cont_col_scroll_event_cb(lv_event_t * e)
{
    static bool is_adjusting = false;
    lv_obj_t * cont = lv_event_get_current_target_obj(e);

    if(!is_adjusting) {
        is_adjusting = true;
        int32_t scroll_y = lv_obj_get_scroll_y(cont);
        int32_t cont_h = lv_obj_get_height(cont);
        int32_t content_h = get_content_height(cont);

        /* Use ITEM_SIZE as vertical item height */
        const int32_t item_height = ITEM_SIZE;

        if(scroll_y <= 0) {
            lv_obj_t * last_child = lv_obj_get_child(cont, (int32_t)(lv_obj_get_child_count(cont) - 1));
            lv_obj_move_to_index(last_child, 0);
            lv_obj_scroll_to_y(cont, scroll_y + item_height, LV_ANIM_OFF);
        }
        else if(scroll_y > content_h - cont_h) {
            lv_obj_t * first_child = lv_obj_get_child(cont, 0);
            lv_obj_move_to_index(first_child, (int32_t)(lv_obj_get_child_count(cont) - 1));
            lv_obj_scroll_to_y(cont, scroll_y - item_height, LV_ANIM_OFF);
        }
        is_adjusting = false;
    }
}

void lv_example_scroll_8(void)
{
    /* Create a scroll container with ROW flex direction */
    lv_obj_t * cont_row = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont_row, 300, 75);
    lv_obj_align(cont_row, LV_ALIGN_TOP_MID, 0, 5);
    lv_obj_set_flex_flow(cont_row, LV_FLEX_FLOW_ROW);
    lv_obj_add_event_cb(cont_row, cont_row_scroll_event_cb, LV_EVENT_SCROLL, NULL);
    /* Hide scrollbar visuals */
    lv_obj_set_scrollbar_mode(cont_row, LV_SCROLLBAR_MODE_OFF);

    /* Create a scroll container with COLUMN flex direction */
    lv_obj_t * cont_col = lv_obj_create(lv_screen_active());
    lv_obj_set_size(cont_col, 200, 150);
    lv_obj_align_to(cont_col, cont_row, LV_ALIGN_OUT_BOTTOM_MID, 0, 5);
    lv_obj_set_flex_flow(cont_col, LV_FLEX_FLOW_COLUMN);
    lv_obj_add_event_cb(cont_col, cont_col_scroll_event_cb, LV_EVENT_SCROLL, NULL);
    /* Hide scrollbar visuals */
    lv_obj_set_scrollbar_mode(cont_col, LV_SCROLLBAR_MODE_OFF);

    /* If the number of items is less than 3, scrolling may not be needed or may cause unexpected behavior. */
    uint32_t i;
    for(i = 0; i < 10; i++) {
        lv_obj_t * obj;
        lv_obj_t * label;

        /*Add items to the row*/
        obj = lv_button_create(cont_row);
        lv_obj_set_size(obj, ITEM_SIZE, LV_PCT(100));

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item %" LV_PRIu32, i + 1);
        lv_obj_center(label);

        /*Add items to the column*/
        obj = lv_button_create(cont_col);
        lv_obj_set_size(obj, LV_PCT(100), ITEM_SIZE);

        label = lv_label_create(obj);
        lv_label_set_text_fmt(label, "Item %" LV_PRIu32, i + 1);
        lv_obj_center(label);
    }
}


#endif