04선택 개수 롤 전환 — 선택된 개수 값이 오르내릴 때마다 배지 숫자의 자리 값이 위아래로 굴러가듯 바뀌는 방식

<main class="stage">
<div class="cbc is-demo" id="cbc">
  <div class="cbc__list">
    <label class="cbc__row">
      <input type="checkbox" class="cbc__input" id="cbcItem0">
      <span class="cbc__box" id="cbcBox0" aria-hidden="true">
        <svg viewBox="0 0 20 20" width="12" height="12"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg>
      </span>
      <span class="cbc__text">기본 배송</span>
    </label>
    <label class="cbc__row">
      <input type="checkbox" class="cbc__input" id="cbcItem1">
      <span class="cbc__box" id="cbcBox1" aria-hidden="true">
        <svg viewBox="0 0 20 20" width="12" height="12"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg>
      </span>
      <span class="cbc__text">선물 포장</span>
    </label>
    <label class="cbc__row">
      <input type="checkbox" class="cbc__input" id="cbcItem2">
      <span class="cbc__box" id="cbcBox2" aria-hidden="true">
        <svg viewBox="0 0 20 20" width="12" height="12"><path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/></svg>
      </span>
      <span class="cbc__text">설치 서비스</span>
    </label>
  </div>
  <span class="cbc__badge">
    <span class="cbc__window">
      <span class="cbc__strip" id="cbcStrip">
        <span>0</span><span>1</span><span>2</span><span>3</span>
      </span>
    </span>
  </span>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// 계산 겹: index.html paint() 가 체크된 개수 → 목표 translateY 값을 만들고, easeOutCubic 을
// rAF 로 직접 적분해 숫자 strip 을 다음 칸으로 굴린다 — clip-path 가 그 칸 하나만 보이는
// 창을 만든다(overflow:hidden 이 아니라 계산된 사각 경계로 자른다).
@include stage($stage-paper);

.cbc {
  display: flex;
  align-items: center;
  gap: $sp-6;
  width: 100%;
  max-width: 300px;
}

.cbc__list {
  display: grid;
  gap: $sp-2;
  flex: 1 1 auto;
}

.cbc__row {
  display: flex;
  align-items: center;
  gap: $sp-2;
  cursor: pointer;
  user-select: none;
}

.cbc__input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.cbc__box {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  border-radius: $r-xs;
  border: 2px solid rgba($subject-ink, .32);
  background: transparent;
  color: transparent;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: background-color $dur-quick $ease-out, border-color $dur-quick $ease-out, color $dur-quick $ease-out;
}

.cbc__box--on {
  background: $subject-blue;
  border-color: $subject-blue;
  color: $subject-cream;
}

.cbc__input:focus-visible + .cbc__box {
  outline: 2px solid $subject-blue-light;
  outline-offset: 2px;
}

.cbc__text {
  color: $subject-ink;
  font-size: 12px;
  font-weight: 600;
}

.cbc__badge {
  flex: 0 0 auto;
  width: 36px;
  height: 36px;
  border-radius: $r-pill;
  background: $subject-blue-deep;
  display: grid;
  place-items: center;
  box-shadow: $shadow-raised;
}

.cbc__window {
  display: block;
  width: 14px;
  height: 18px;
  overflow: hidden;
  clip-path: inset(0 0 0 0 round $r-xs);
}

.cbc__strip {
  display: flex;
  flex-direction: column;
  align-items: center;
  will-change: transform;

  span {
    height: 18px;
    line-height: 18px;
    color: $subject-cream;
    font-weight: 800;
    font-size: 13px;
  }
}

@media (max-width: 340px) {
  .cbc { gap: $sp-4; }
  .cbc__text { font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  .cbc__box { transition: none; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cbc {
  display: flex;
  align-items: center;
  gap: 24px;
  width: 100%;
  max-width: 300px;
}

.cbc__list {
  display: grid;
  gap: 8px;
  flex: 1 1 auto;
}

.cbc__row {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  user-select: none;
}

.cbc__input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.cbc__box {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  border-radius: 4px;
  border: 2px solid rgba(23, 20, 26, 0.32);
  background: transparent;
  color: transparent;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: background-color 220ms ease-out, border-color 220ms ease-out, color 220ms ease-out;
}

.cbc__box--on {
  background: #2f6df6;
  border-color: #2f6df6;
  color: #fff7e6;
}

.cbc__input:focus-visible + .cbc__box {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

.cbc__text {
  color: #17141a;
  font-size: 12px;
  font-weight: 600;
}

.cbc__badge {
  flex: 0 0 auto;
  width: 36px;
  height: 36px;
  border-radius: 999px;
  background: #0a4fe8;
  display: grid;
  place-items: center;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.cbc__window {
  display: block;
  width: 14px;
  height: 18px;
  overflow: hidden;
  clip-path: inset(0 0 0 0 round 4px);
}

.cbc__strip {
  display: flex;
  flex-direction: column;
  align-items: center;
  will-change: transform;
}
.cbc__strip span {
  height: 18px;
  line-height: 18px;
  color: #fff7e6;
  font-weight: 800;
  font-size: 13px;
}

@media (max-width: 340px) {
  .cbc {
    gap: 16px;
  }
  .cbc__text {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cbc__box {
    transition: none;
  }
}

(function () {
  var ROW_H = 18; // px, 숫자 롤 한 칸 높이
  var ROLL_MS = 260; // 계산 겹 상수: 숫자가 다음 칸으로 굴러가는 데 걸리는 실제 시간(ms)
  var CYCLE_MS = 560; // 자동 루프가 항목을 하나씩 체크하는 간격
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var root = document.getElementById('cbc');
  var strip = document.getElementById('cbcStrip');
  var inputs = [document.getElementById('cbcItem0'), document.getElementById('cbcItem1'), document.getElementById('cbcItem2')];
  var boxes = [document.getElementById('cbcBox0'), document.getElementById('cbcBox1'), document.getElementById('cbcBox2')];

  var isDemo = true;
  var pos = 0, from = 0, to = 0, rollStart = 0, rolling = false;

  function human() {
    if (isDemo) { root.classList.remove('is-demo'); isDemo = false; }
  }

  function easeOutCubic(t) { return 1 - Math.pow(1 - t, 3); }

  function currentPos(ts) {
    if (!rolling) return to;
    var t = Math.min(1, (ts - rollStart) / ROLL_MS);
    return from + (to - from) * easeOutCubic(t);
  }

  function paint(ts) {
    inputs.forEach(function (inp, i) { boxes[i].classList.toggle('cbc__box--on', inp.checked); });
    var count = inputs.filter(function (i) { return i.checked; }).length;
    var target = -count * ROW_H;
    if (target !== to) {
      from = currentPos(ts);
      to = target;
      rollStart = ts;
      rolling = true;
    }
  }

  inputs.forEach(function (inp) {
    inp.addEventListener('change', function () { human(); paint(performance.now()); });
  });

  var cycleStart = 0;
  var lastN = -1;
  var SEQ = [[false, false, false], [true, false, false], [true, true, false], [true, true, true], [true, true, false], [true, false, false], [false, false, false]];

  function loop(ts) {
    if (!cycleStart) cycleStart = ts;

    if (isDemo) {
      var n = Math.floor((ts - cycleStart) / CYCLE_MS) % SEQ.length;
      if (n !== lastN) {
        lastN = n;
        var state = SEQ[n];
        inputs.forEach(function (inp, i) { inp.checked = state[i]; });
        paint(ts);
      }
    }

    pos = currentPos(ts);
    strip.style.transform = 'translateY(' + pos.toFixed(2) + 'px)';

    requestAnimationFrame(loop);
  }

  if (reduce) { ROLL_MS = 1; }
  requestAnimationFrame(loop);
})();

// CountBadgeRoll — vanilla 판(run/368/demo/04-custom-checkbox-count-badge-roll/index.html) 의 React 포트.
// 체크된 개수 → 목표 translateY 값을 만들고 easeOutCubic 을 rAF 로 직접 적분해 숫자 strip 을
// 다음 칸으로 굴린다. clip-path 가 그 칸 하나만 보이는 창을 만든다.
import { useEffect, useRef } from "react";
import styles from "./CountBadgeRoll.module.scss";

type Box<T> = { current: T };

const ITEMS = [
  { id: "item0", label: "기본 배송" },
  { id: "item1", label: "선물 포장" },
  { id: "item2", label: "설치 서비스" },
];

export default function CountBadgeRoll() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const stripRef = useRef(null) as unknown as Box<HTMLSpanElement>;
  const inputRefs = useRef([null, null, null]) as unknown as Box<(HTMLInputElement | null)[]>;
  const boxRefs = useRef([null, null, null]) as unknown as Box<(HTMLSpanElement | null)[]>;
  const rafRef = useRef(0) as unknown as Box<number>;

  useEffect(() => {
    const ROW_H = 18; // px, 숫자 롤 한 칸 높이
    let ROLL_MS = 260; // 계산 겹 상수: 숫자가 다음 칸으로 굴러가는 데 걸리는 실제 시간(ms)
    const CYCLE_MS = 560; // 자동 루프가 항목을 하나씩 체크하는 간격
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    const root = rootRef.current;
    const strip = stripRef.current;
    const inputs = inputRefs.current;
    const boxes = boxRefs.current;
    if (!root || !strip) return;

    let isDemo = true;
    let pos = 0, from = 0, to = 0, rollStart = 0, rolling = false;

    function human() {
      if (isDemo) { root!.classList.remove(styles.isDemo); isDemo = false; }
    }

    function easeOutCubic(t: number) { return 1 - Math.pow(1 - t, 3); }

    function currentPos(ts: number) {
      if (!rolling) return to;
      const t = Math.min(1, (ts - rollStart) / ROLL_MS);
      return from + (to - from) * easeOutCubic(t);
    }

    function paint(ts: number) {
      inputs.forEach((inp, i) => { boxes[i]?.classList.toggle(styles.boxOn, inp ? inp.checked : false); });
      const count = inputs.filter((i) => i?.checked).length;
      const target = -count * ROW_H;
      if (target !== to) {
        from = currentPos(ts);
        to = target;
        rollStart = ts;
        rolling = true;
      }
    }

    const handlers = inputs.map((inp) => {
      const fn = () => { human(); paint(performance.now()); };
      inp?.addEventListener("change", fn);
      return fn;
    });

    let cycleStart = 0;
    let lastN = -1;
    const SEQ = [
      [false, false, false], [true, false, false], [true, true, false], [true, true, true],
      [true, true, false], [true, false, false], [false, false, false],
    ];

    function loop(ts: number) {
      if (!cycleStart) cycleStart = ts;

      if (isDemo) {
        const n = Math.floor((ts - cycleStart) / CYCLE_MS) % SEQ.length;
        if (n !== lastN) {
          lastN = n;
          const state = SEQ[n];
          inputs.forEach((inp, i) => { if (inp) inp.checked = state[i]; });
          paint(ts);
        }
      }

      pos = currentPos(ts);
      strip!.style.transform = "translateY(" + pos.toFixed(2) + "px)";

      rafRef.current = requestAnimationFrame(loop);
    }

    if (reduce) { ROLL_MS = 1; }
    rafRef.current = requestAnimationFrame(loop);

    return () => {
      inputs.forEach((inp, i) => inp?.removeEventListener("change", handlers[i]));
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.cbc + " " + styles.isDemo} ref={rootRef}>
        <div className={styles.cbcList}>
          {ITEMS.map((it, i) => (
            <label className={styles.cbcRow} key={it.id}>
              <input
                type="checkbox"
                className={styles.cbcInput}
                ref={(el: HTMLInputElement | null) => { inputRefs.current[i] = el; }}
              />
              <span
                className={styles.cbcBox}
                ref={(el: HTMLSpanElement | null) => { boxRefs.current[i] = el; }}
                aria-hidden="true"
              >
                <svg viewBox="0 0 20 20" width={12} height={12}>
                  <path d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" strokeLinejoin="round" />
                </svg>
              </span>
              <span className={styles.cbcText}>{it.label}</span>
            </label>
          ))}
        </div>
        <span className={styles.cbcBadge}>
          <span className={styles.cbcWindow}>
            <span className={styles.cbcStrip} ref={stripRef}>
              <span>0</span><span>1</span><span>2</span><span>3</span>
            </span>
          </span>
        </span>
      </div>
    </main>
  );
}