02Indeterminate-dash toggle — when only some child items are selected, the parent box's mark value switches to a dash shape

<main class="stage">
<div class="cbi is-demo" id="cbi">
  <label class="cbi__row cbi__row--parent">
    <input type="checkbox" class="cbi__input" id="cbiParent">
    <span class="cbi__box" id="cbiParentBox" aria-hidden="true">
      <svg class="cbi__svg" viewBox="0 0 20 20" width="14" height="14">
        <path class="cbi__check" d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" stroke-width="2.6" stroke-linecap="round" stroke-linejoin="round"/>
        <line class="cbi__dash" x1="5" y1="10" x2="15" y2="10" stroke="currentColor" stroke-width="2.6" stroke-linecap="round"/>
      </svg>
    </span>
    <span class="cbi__text">Select all notifications</span>
  </label>
  <div class="cbi__children">
    <label class="cbi__row">
      <input type="checkbox" class="cbi__input" id="cbiChild0">
      <span class="cbi__box" id="cbiChildBox0" aria-hidden="true">
        <svg class="cbi__svg" viewBox="0 0 20 20" width="12" height="12">
          <path class="cbi__check" 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="cbi__text">Email notifications</span>
    </label>
    <label class="cbi__row">
      <input type="checkbox" class="cbi__input" id="cbiChild1">
      <span class="cbi__box" id="cbiChildBox1" aria-hidden="true">
        <svg class="cbi__svg" viewBox="0 0 20 20" width="12" height="12">
          <path class="cbi__check" 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="cbi__text">SMS notifications</span>
    </label>
    <label class="cbi__row">
      <input type="checkbox" class="cbi__input" id="cbiChild2">
      <span class="cbi__box" id="cbiChildBox2" aria-hidden="true">
        <svg class="cbi__svg" viewBox="0 0 20 20" width="12" height="12">
          <path class="cbi__check" 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="cbi__text">Push notifications</span>
    </label>
  </div>
</div>
</main>

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

// 계산 겹: index.html paintParent() 가 자식 선택 개수 ÷ 전체 개수로 선택 비율 값을 만들고,
// 그 값을 --cbi-alpha 로 사영해 부모 박스 배경의 실제 투명도를 만든다 — 체크·빈칸 두 상태만
// 있는 on/off 토글이 아니라 비율 값이 배경 진하기를 연속으로 결정한다.
@include stage($stage-yellow);

.cbi {
  display: grid;
  gap: $sp-3;
  width: 100%;
  max-width: 260px;
}

.cbi__row {
  display: flex;
  align-items: center;
  gap: $sp-3;
  cursor: pointer;
  user-select: none;
}

.cbi__row--parent {
  padding-bottom: $sp-2;
  border-bottom: 1px solid rgba($subject-ink, .18);
}

.cbi__children {
  display: grid;
  gap: $sp-2;
  padding-left: $sp-6;
}

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

.cbi__box {
  --cbi-alpha: 0;
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  border-radius: $r-sm;
  border: 2px solid rgba($subject-ink, .4);
  background: rgba(#{red($subject-blue)}, #{green($subject-blue)}, #{blue($subject-blue)}, var(--cbi-alpha));
  color: $subject-cream;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: border-color $dur-quick $ease-out, background-color $dur-quick $ease-out;
}

.cbi__row--parent .cbi__box {
  width: 24px;
  height: 24px;
}

.cbi__check, .cbi__dash {
  opacity: 0;
  transition: opacity $dur-quick $ease-out;
}

.cbi__box--on {
  border-color: $subject-blue;
  .cbi__check { opacity: 1; }
}

.cbi__box--mixed {
  border-color: $subject-blue;
  .cbi__dash { opacity: 1; }
}

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

.cbi__text {
  color: $subject-ink;
  font-size: 13px;
  font-weight: 600;
}

.cbi__row--parent .cbi__text {
  font-size: 14px;
  font-weight: 700;
}

@media (max-width: 340px) {
  .cbi__children { padding-left: $sp-4; }
  .cbi__text { font-size: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  .cbi__box, .cbi__check, .cbi__dash { transition: none; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cbi {
  display: grid;
  gap: 12px;
  width: 100%;
  max-width: 260px;
}

.cbi__row {
  display: flex;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  user-select: none;
}

.cbi__row--parent {
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(23, 20, 26, 0.18);
}

.cbi__children {
  display: grid;
  gap: 8px;
  padding-left: 24px;
}

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

.cbi__box {
  --cbi-alpha: 0;
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  border-radius: 8px;
  border: 2px solid rgba(23, 20, 26, 0.4);
  background: rgba(47, 109, 246, var(--cbi-alpha));
  color: #fff7e6;
  display: grid;
  place-items: center;
  box-sizing: border-box;
  transition: border-color 220ms ease-out, background-color 220ms ease-out;
}

.cbi__row--parent .cbi__box {
  width: 24px;
  height: 24px;
}

.cbi__check, .cbi__dash {
  opacity: 0;
  transition: opacity 220ms ease-out;
}

.cbi__box--on {
  border-color: #2f6df6;
}
.cbi__box--on .cbi__check {
  opacity: 1;
}

.cbi__box--mixed {
  border-color: #2f6df6;
}
.cbi__box--mixed .cbi__dash {
  opacity: 1;
}

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

.cbi__text {
  color: #17141a;
  font-size: 13px;
  font-weight: 600;
}

.cbi__row--parent .cbi__text {
  font-size: 14px;
  font-weight: 700;
}

@media (max-width: 340px) {
  .cbi__children {
    padding-left: 16px;
  }
  .cbi__text {
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cbi__box, .cbi__check, .cbi__dash {
    transition: none;
  }
}

(function () {
  var MIX_ALPHA = .22; // 계산 겹 상수: 자식이 0개 선택됐을 때도 남기는 최소 배경 알파
  var CYCLE_MS = 520; // 자동 루프가 자식 하나씩 상태를 바꾸는 간격
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var root = document.getElementById('cbi');
  var parent = document.getElementById('cbiParent');
  var parentBox = document.getElementById('cbiParentBox');
  var children = [
    document.getElementById('cbiChild0'),
    document.getElementById('cbiChild1'),
    document.getElementById('cbiChild2')
  ];
  var childBoxes = [
    document.getElementById('cbiChildBox0'),
    document.getElementById('cbiChildBox1'),
    document.getElementById('cbiChildBox2')
  ];

  var isDemo = true;

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

  function paintChildren() {
    children.forEach(function (c, i) { childBoxes[i].classList.toggle('cbi__box--on', c.checked); });
  }

  function paintParent() {
    paintChildren();
    var checkedCount = children.filter(function (c) { return c.checked; }).length;
    var ratio = checkedCount / children.length; // 계산 겹: 선택 비율 값
    var all = ratio === 1, none = ratio === 0;
    parent.checked = all;
    parent.indeterminate = !all && !none;
    parentBox.classList.toggle('cbi__box--on', all);
    parentBox.classList.toggle('cbi__box--mixed', !all && !none);
    // 계산 겹: 선택 비율을 배경 알파로 직접 사영한다(MIX_ALPHA 를 바닥으로 두고 남은 폭을 ratio 만큼 채움)
    var alpha = none ? 0 : (MIX_ALPHA + (1 - MIX_ALPHA) * ratio);
    parentBox.style.setProperty('--cbi-alpha', alpha.toFixed(3));
  }

  function setChild(idx, val) {
    children[idx].checked = val;
    paintParent();
  }

  children.forEach(function (c) {
    c.addEventListener('change', function () { human(); paintParent(); });
  });

  parent.addEventListener('change', function () {
    human();
    var next = parent.checked;
    children.forEach(function (c) { c.checked = next; });
    paintParent();
  });

  // 자동 루프: 자식을 하나씩 켜서 없음 → 부분 → 전체를 보여주고, 다시 하나씩 끈다
  var SEQ = [
    [false, false, false], [true, false, false], [true, true, false], [true, true, true],
    [true, true, false], [true, false, false], [false, false, false]
  ];
  var si = 0;
  var autoTimer = null;

  function autoTick() {
    var state = SEQ[si];
    children.forEach(function (c, i) { c.checked = state[i]; });
    paintParent();
    si = (si + 1) % SEQ.length;
  }

  if (!reduce) { autoTimer = setInterval(autoTick, CYCLE_MS); autoTick(); }
  else { autoTick(); }
})();

// IndeterminateDash — vanilla 판(run/368/demo/02-custom-checkbox-indeterminate-dash/index.html) 의 React 포트.
// 자식 선택 비율(ratio)을 계산해 네이티브 indeterminate 값과 배경 알파(--cbi-alpha)를 함께 만든다.
import { useEffect, useRef } from "react";
import styles from "./IndeterminateDash.module.scss";

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

const CHILDREN = [
  { id: "child0", label: "이메일 알림" },
  { id: "child1", label: "문자 알림" },
  { id: "child2", label: "푸시 알림" },
];

export default function IndeterminateDash() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const parentRef = useRef(null) as unknown as Box<HTMLInputElement>;
  const parentBoxRef = useRef(null) as unknown as Box<HTMLSpanElement>;
  const childRefs = useRef([null, null, null]) as unknown as Box<(HTMLInputElement | null)[]>;
  const childBoxRefs = useRef([null, null, null]) as unknown as Box<(HTMLSpanElement | null)[]>;
  const timerRef = useRef(0) as unknown as Box<number>;

  useEffect(() => {
    const MIX_ALPHA = 0.22; // 계산 겹 상수: 자식이 0개 선택됐을 때도 남기는 최소 배경 알파
    const CYCLE_MS = 520; // 자동 루프가 자식 하나씩 상태를 바꾸는 간격
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    const root = rootRef.current;
    const parent = parentRef.current;
    const parentBox = parentBoxRef.current;
    const children = childRefs.current;
    const childBoxes = childBoxRefs.current;
    if (!root || !parent || !parentBox) return;

    let isDemo = true;

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

    function paintChildren() {
      children.forEach((c, i) => { childBoxes[i]?.classList.toggle(styles.boxOn, c ? c.checked : false); });
    }

    function paintParent() {
      paintChildren();
      const checkedCount = children.filter((c) => c?.checked).length;
      const ratio = checkedCount / children.length; // 계산 겹: 선택 비율 값
      const all = ratio === 1, none = ratio === 0;
      parent!.checked = all;
      parent!.indeterminate = !all && !none;
      parentBox!.classList.toggle(styles.boxOn, all);
      parentBox!.classList.toggle(styles.boxMixed, !all && !none);
      // 계산 겹: 선택 비율을 배경 알파로 직접 사영한다(MIX_ALPHA 를 바닥으로 두고 남은 폭을 ratio 만큼 채움)
      const alpha = none ? 0 : (MIX_ALPHA + (1 - MIX_ALPHA) * ratio);
      parentBox!.style.setProperty("--cbi-alpha", alpha.toFixed(3));
    }

    const childHandlers = children.map((c) => {
      const fn = () => { human(); paintParent(); };
      c?.addEventListener("change", fn);
      return fn;
    });

    function onParentChange() {
      human();
      const next = parent!.checked;
      children.forEach((c) => { if (c) c.checked = next; });
      paintParent();
    }
    parent.addEventListener("change", onParentChange);

    const SEQ = [
      [false, false, false], [true, false, false], [true, true, false], [true, true, true],
      [true, true, false], [true, false, false], [false, false, false],
    ];
    let si = 0;

    function autoTick() {
      const state = SEQ[si];
      children.forEach((c, i) => { if (c) c.checked = state[i]; });
      paintParent();
      si = (si + 1) % SEQ.length;
    }

    if (!reduce) { timerRef.current = window.setInterval(autoTick, CYCLE_MS); autoTick(); }
    else { autoTick(); }

    return () => {
      children.forEach((c, i) => c?.removeEventListener("change", childHandlers[i]));
      parent.removeEventListener("change", onParentChange);
      window.clearInterval(timerRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.cbi + " " + styles.isDemo} ref={rootRef}>
        <label className={styles.cbiRow + " " + styles.cbiRowParent}>
          <input type="checkbox" className={styles.cbiInput} ref={parentRef} />
          <span className={styles.cbiBox} ref={parentBoxRef} aria-hidden="true">
            <svg className={styles.cbiSvg} viewBox="0 0 20 20" width={14} height={14}>
              <path className={styles.cbiCheck} d="M4 10.5l3.5 3.5L16 5.5" fill="none" stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" strokeLinejoin="round" />
              <line className={styles.cbiDash} x1={5} y1={10} x2={15} y2={10} stroke="currentColor" strokeWidth={2.6} strokeLinecap="round" />
            </svg>
          </span>
          <span className={styles.cbiText}>알림 전체 선택</span>
        </label>
        <div className={styles.cbiChildren}>
          {CHILDREN.map((c, i) => (
            <label className={styles.cbiRow} key={c.id}>
              <input
                type="checkbox"
                className={styles.cbiInput}
                ref={(el: HTMLInputElement | null) => { childRefs.current[i] = el; }}
              />
              <span
                className={styles.cbiBox}
                ref={(el: HTMLSpanElement | null) => { childBoxRefs.current[i] = el; }}
                aria-hidden="true"
              >
                <svg className={styles.cbiSvg} viewBox="0 0 20 20" width={12} height={12}>
                  <path className={styles.cbiCheck} 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.cbiText}>{c.label}</span>
            </label>
          ))}
        </div>
      </div>
    </main>
  );
}