06外側クリック終了 — メニューの外をクリックした状態になると透明度の値が下がって消える方式

<main class="stage">
<div class="cm is-demo" id="cm">
  <div class="cm__backdrop" id="cmBackdrop"></div>
  <div class="cm__field" id="cmField">
    <span class="cm__hint">右クリック → 外側をクリック</span>
  </div>
  <div class="cm__menu" id="cmMenu" role="menu">
    <button class="cm__item" type="button" role="menuitem">
      <span class="cm__ic"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="M216 40v128h-48V88H88V40Z" opacity=".2"/><path d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></g></svg></span>
      <span>コピー</span>
    </button>
    <button class="cm__item" type="button" role="menuitem">
      <span class="cm__ic"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="M208 48v168a8 8 0 0 1-8 8H56a8 8 0 0 1-8-8V48a8 8 0 0 1 8-8h40a39.83 39.83 0 0 0-8 24v8h80v-8a39.83 39.83 0 0 0-8-24h40a8 8 0 0 1 8 8" opacity=".2"/><path d="M200 32h-36.26a47.92 47.92 0 0 0-71.48 0H56a16 16 0 0 0-16 16v168a16 16 0 0 0 16 16h144a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m-72 0a32 32 0 0 1 32 32H96a32 32 0 0 1 32-32m72 184H56V48h26.75A47.9 47.9 0 0 0 80 64v8a8 8 0 0 0 8 8h80a8 8 0 0 0 8-8v-8a47.9 47.9 0 0 0-2.75-16H200Z"/></g></svg></span>
      <span>貼り付け</span>
    </button>
    <button class="cm__item" type="button" role="menuitem">
      <span class="cm__ic"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="m221.66 90.34l-56 56l-40-40l56-56l29.66-29.66a8 8 0 0 1 11.31 0L221.66 79a8 8 0 0 1 0 11.34" opacity=".2"/><path d="m227.31 73.37l-44.68-44.69a16 16 0 0 0-22.63 0L36.69 152A15.86 15.86 0 0 0 32 163.31V208a16 16 0 0 0 16 16h44.69a15.86 15.86 0 0 0 11.31-4.69L227.31 96a16 16 0 0 0 0-22.63M92.69 208H48v-44.69l88-88L180.69 120ZM192 108.68L147.31 64l24-24L216 84.68Z"/></g></svg></span>
      <span>名前を変更</span>
    </button>
    <button class="cm__item cm__item--danger" type="button" role="menuitem">
      <span class="cm__ic"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="M200 56v152a8 8 0 0 1-8 8H64a8 8 0 0 1-8-8V56Z" opacity=".2"/><path d="M216 48h-40v-8a24 24 0 0 0-24-24h-48a24 24 0 0 0-24 24v8H40a8 8 0 0 0 0 16h8v144a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16V64h8a8 8 0 0 0 0-16M96 40a8 8 0 0 1 8-8h48a8 8 0 0 1 8 8v8H96Zm96 168H64V64h128Zm-80-104v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0m48 0v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0"/></g></svg></span>
      <span>削除</span>
    </button>
  </div>
</div>
</main>

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

// 계산 겹: 바깥 클릭 좌표가 메뉴 상자(getBoundingClientRect) 밖인지 사각형 포함 판정으로 재고,
// 밖이면 배경(backdrop)의 불투명도를 0으로 되돌리는 것과 동시에 메뉴를 fade-out 시킨다.
@include stage($stage-orange);

.cm {
  position: relative;
  width: 100%;
  height: 100%;
  display: grid;
  place-items: center;
}

.cm__field {
  width: clamp(190px, 60vw, 260px);
  height: 130px;
  border-radius: $r-card;
  background: $subject-ink;
  color: $subject-cream;
  display: grid;
  place-items: center;
  padding: $sp-3;
  box-sizing: border-box;
  font: 600 14px/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  text-align: center;
  user-select: none;
  position: relative;
  z-index: 1;
}

.cm__hint { opacity: .8; font-weight: 500; font-size: 12px; }

.cm__backdrop {
  position: fixed;
  inset: 0;
  background: rgba($subject-ink, .28);
  opacity: 0;
  pointer-events: none;
  transition: opacity $dur-base $ease-out;
  z-index: 4;

  &.is-on { opacity: 1; pointer-events: auto; }
}

.cm__menu {
  position: fixed;
  top: 0;
  left: 0;
  min-width: 168px;
  background: $stage-paper;
  border-radius: $r-sm;
  box-shadow: $shadow-raised;
  padding: $sp-1;
  display: grid;
  gap: $sp-1;
  opacity: 0;
  transform: translateY(-6px);
  pointer-events: none;
  transition: opacity $dur-base $ease-out, transform $dur-base $ease-out;
  z-index: 5;

  &.is-open { opacity: 1; transform: translateY(0); pointer-events: auto; }
}

.cm__item {
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-2 $sp-3;
  border: 0;
  background: none;
  border-radius: $r-xs;
  font: 500 13px/1.2 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $subject-ink;
  cursor: pointer;
  text-align: left;

  &:hover, &:focus-visible { background: rgba($subject-ink, .08); }
  &--danger { color: $error; }
}

.cm__ic {
  width: 16px;
  height: 16px;
  flex: none;
  color: $subject-blue;

  svg { display: block; width: 100%; height: 100%; }
}
.cm__item--danger .cm__ic { color: $error; }

@media (max-width: 340px) {
  .cm__field { width: 176px; height: 108px; font-size: 12px; padding: $sp-2; }
  .cm__menu { min-width: 144px; }
  .cm__item { padding: $sp-1 $sp-2; font-size: 12px; }
}

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

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cm {
  position: relative;
  width: 100%;
  height: 100%;
  display: grid;
  place-items: center;
}

.cm__field {
  width: clamp(190px, 60vw, 260px);
  height: 130px;
  border-radius: 16px;
  background: #17141a;
  color: #fff7e6;
  display: grid;
  place-items: center;
  padding: 12px;
  box-sizing: border-box;
  font: 600 14px/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  text-align: center;
  user-select: none;
  position: relative;
  z-index: 1;
}

.cm__hint {
  opacity: 0.8;
  font-weight: 500;
  font-size: 12px;
}

.cm__backdrop {
  position: fixed;
  inset: 0;
  background: rgba(23, 20, 26, 0.28);
  opacity: 0;
  pointer-events: none;
  transition: opacity 300ms ease-out;
  z-index: 4;
}
.cm__backdrop.is-on {
  opacity: 1;
  pointer-events: auto;
}

.cm__menu {
  position: fixed;
  top: 0;
  left: 0;
  min-width: 168px;
  background: #ffffff;
  border-radius: 8px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  padding: 4px;
  display: grid;
  gap: 4px;
  opacity: 0;
  transform: translateY(-6px);
  pointer-events: none;
  transition: opacity 300ms ease-out, transform 300ms ease-out;
  z-index: 5;
}
.cm__menu.is-open {
  opacity: 1;
  transform: translateY(0);
  pointer-events: auto;
}

.cm__item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 0;
  background: none;
  border-radius: 4px;
  font: 500 13px/1.2 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #17141a;
  cursor: pointer;
  text-align: left;
}
.cm__item:hover, .cm__item:focus-visible {
  background: rgba(23, 20, 26, 0.08);
}
.cm__item--danger {
  color: #c2361a;
}

.cm__ic {
  width: 16px;
  height: 16px;
  flex: none;
  color: #2f6df6;
}
.cm__ic svg {
  display: block;
  width: 100%;
  height: 100%;
}

.cm__item--danger .cm__ic {
  color: #c2361a;
}

@media (max-width: 340px) {
  .cm__field {
    width: 176px;
    height: 108px;
    font-size: 12px;
    padding: 8px;
  }
  .cm__menu {
    min-width: 144px;
  }
  .cm__item {
    padding: 4px 8px;
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cm__menu, .cm__backdrop {
    transition: none;
  }
}

(function () {
  var field = document.getElementById('cmField');
  var menu = document.getElementById('cmMenu');
  var backdrop = document.getElementById('cmBackdrop');
  var root = document.getElementById('cm');
  var GAP = 6;

  function positionAt(x, y) {
    var mw = menu.offsetWidth, mh = menu.offsetHeight;
    var vw = document.documentElement.clientWidth, vh = document.documentElement.clientHeight;
    var px = Math.max(GAP, Math.min(x, vw - mw - GAP));
    var py = Math.max(GAP, Math.min(y, vh - mh - GAP));
    menu.style.left = px.toFixed(0) + 'px';
    menu.style.top = py.toFixed(0) + 'px';
  }
  function open(x, y) {
    positionAt(x, y);
    menu.classList.add('is-open');
    backdrop.classList.add('is-on');
  }
  function close() {
    menu.classList.remove('is-open');
    backdrop.classList.remove('is-on');
  }

  // 계산 겹: 클릭 좌표가 메뉴의 경계 사각형(getBoundingClientRect) 안에 드는지 네 부등식으로
  // 판정해 바깥일 때만 backdrop 과 메뉴를 함께 페이드아웃한다.
  function isInside(rect, x, y) {
    return x >= rect.left && x <= rect.right && y >= rect.top && y <= rect.bottom;
  }

  field.addEventListener('contextmenu', function (e) {
    e.preventDefault();
    root.classList.remove('is-demo'); stopAutoplay();
    open(e.clientX, e.clientY);
  });
  backdrop.addEventListener('pointerdown', function (e) {
    var r = menu.getBoundingClientRect();
    if (!isInside(r, e.clientX, e.clientY)) close();
  });
  menu.addEventListener('click', close);

  // 자동 루프: 필드 위에 메뉴를 연 뒤 배경 바깥 지점을 클릭해 backdrop 과 메뉴가 함께
  // 페이드아웃되는 것을 보여준다.
  var step = 0, autoTimer = null;
  function autoTick() {
    if (step === 0) { var r = field.getBoundingClientRect(); open(r.left + r.width * 0.3, r.top + r.height * 0.3); }
    else if (step === 2) { close(); }
    step = (step + 1) % 4;
  }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } }
  if (!reduce) { autoTimer = setInterval(autoTick, 300); autoTick(); }
})();

import { useEffect, useRef } from "react";
import styles from "./BackdropDismissFade.module.scss";

const ICON_COPY = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="M216 40v128h-48V88H88V40Z" opacity=".2"/><path d="M216 32H88a8 8 0 0 0-8 8v40H40a8 8 0 0 0-8 8v128a8 8 0 0 0 8 8h128a8 8 0 0 0 8-8v-40h40a8 8 0 0 0 8-8V40a8 8 0 0 0-8-8m-56 176H48V96h112Zm48-48h-32V88a8 8 0 0 0-8-8H96V48h112Z"/></g></svg>';
const ICON_PASTE = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="M208 48v168a8 8 0 0 1-8 8H56a8 8 0 0 1-8-8V48a8 8 0 0 1 8-8h40a39.83 39.83 0 0 0-8 24v8h80v-8a39.83 39.83 0 0 0-8-24h40a8 8 0 0 1 8 8" opacity=".2"/><path d="M200 32h-36.26a47.92 47.92 0 0 0-71.48 0H56a16 16 0 0 0-16 16v168a16 16 0 0 0 16 16h144a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m-72 0a32 32 0 0 1 32 32H96a32 32 0 0 1 32-32m72 184H56V48h26.75A47.9 47.9 0 0 0 80 64v8a8 8 0 0 0 8 8h80a8 8 0 0 0 8-8v-8a47.9 47.9 0 0 0-2.75-16H200Z"/></g></svg>';
const ICON_RENAME = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="m221.66 90.34l-56 56l-40-40l56-56l29.66-29.66a8 8 0 0 1 11.31 0L221.66 79a8 8 0 0 1 0 11.34" opacity=".2"/><path d="m227.31 73.37l-44.68-44.69a16 16 0 0 0-22.63 0L36.69 152A15.86 15.86 0 0 0 32 163.31V208a16 16 0 0 0 16 16h44.69a15.86 15.86 0 0 0 11.31-4.69L227.31 96a16 16 0 0 0 0-22.63M92.69 208H48v-44.69l88-88L180.69 120ZM192 108.68L147.31 64l24-24L216 84.68Z"/></g></svg>';
const ICON_TRASH = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256"><g fill="currentColor"><path d="M200 56v152a8 8 0 0 1-8 8H64a8 8 0 0 1-8-8V56Z" opacity=".2"/><path d="M216 48h-40v-8a24 24 0 0 0-24-24h-48a24 24 0 0 0-24 24v8H40a8 8 0 0 0 0 16h8v144a16 16 0 0 0 16 16h128a16 16 0 0 0 16-16V64h8a8 8 0 0 0 0-16M96 40a8 8 0 0 1 8-8h48a8 8 0 0 1 8 8v8H96Zm96 168H64V64h128Zm-80-104v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0m48 0v64a8 8 0 0 1-16 0v-64a8 8 0 0 1 16 0"/></g></svg>';

export type BackdropDismissFadeProps = {
  color?: string;
};

export default function BackdropDismissFade({
  color = "#2f6df6",
}: BackdropDismissFadeProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const field = root.querySelector<HTMLDivElement>(`.${styles.field}`);
    const menu = root.querySelector<HTMLDivElement>(`.${styles.menu}`);
    const backdrop = root.querySelector<HTMLDivElement>(`.${styles.backdrop}`);
    if (!field || !menu || !backdrop) return;
    const GAP = 6;

    function positionAt(x: number, y: number) {
      const mw = menu!.offsetWidth, mh = menu!.offsetHeight;
      const vw = document.documentElement.clientWidth, vh = document.documentElement.clientHeight;
      const px = Math.max(GAP, Math.min(x, vw - mw - GAP));
      const py = Math.max(GAP, Math.min(y, vh - mh - GAP));
      menu!.style.left = px.toFixed(0) + "px";
      menu!.style.top = py.toFixed(0) + "px";
    }
    function open(x: number, y: number) { positionAt(x, y); menu!.classList.add(styles.open); backdrop!.classList.add(styles.backdropOn); }
    function close() { menu!.classList.remove(styles.open); backdrop!.classList.remove(styles.backdropOn); }

    // 계산 겹: 클릭 좌표가 메뉴의 경계 사각형 안에 드는지 네 부등식으로 판정해 바깥일 때만
    // backdrop 과 메뉴를 함께 페이드아웃한다.
    function isInside(rect: DOMRect, x: number, y: number) {
      return x >= rect.left && x <= rect.right && y >= rect.top && y <= rect.bottom;
    }

    function onContextMenu(e: MouseEvent) { e.preventDefault(); stopAutoplay(); open(e.clientX, e.clientY); }
    function onBackdropDown(e: PointerEvent) {
      const r = menu!.getBoundingClientRect();
      if (!isInside(r, e.clientX, e.clientY)) close();
    }
    field.addEventListener("contextmenu", onContextMenu);
    backdrop.addEventListener("pointerdown", onBackdropDown);
    menu.addEventListener("click", close);

    let step = 0;
    let autoTimer: number | null = null;
    function autoTick() {
      if (step === 0) { const r = field!.getBoundingClientRect(); open(r.left + r.width * 0.3, r.top + r.height * 0.3); }
      else if (step === 2) { close(); }
      step = (step + 1) % 4;
    }
    function stopAutoplay() { if (autoTimer !== null) { window.clearInterval(autoTimer); autoTimer = null; } }
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) { autoTimer = window.setInterval(autoTick, 300); autoTick(); }

    return () => {
      stopAutoplay();
      field.removeEventListener("contextmenu", onContextMenu);
      backdrop.removeEventListener("pointerdown", onBackdropDown);
    };
  }, []);

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.cm}>
        <div className={styles.backdrop} />
        <div className={styles.field}>
          <span className={styles.hint}>우클릭 → 바깥 클릭</span>
        </div>
        <div className={styles.menu} role="menu">
          <button type="button" className={styles.item} role="menuitem">
            <span className={styles.ic} style={{ color }} dangerouslySetInnerHTML={{ __html: ICON_COPY }} />
            <span>복사</span>
          </button>
          <button type="button" className={styles.item} role="menuitem">
            <span className={styles.ic} style={{ color }} dangerouslySetInnerHTML={{ __html: ICON_PASTE }} />
            <span>붙여넣기</span>
          </button>
          <button type="button" className={styles.item} role="menuitem">
            <span className={styles.ic} style={{ color }} dangerouslySetInnerHTML={{ __html: ICON_RENAME }} />
            <span>이름 바꾸기</span>
          </button>
          <button type="button" className={`${styles.item} ${styles.danger}`} role="menuitem">
            <span className={styles.ic} dangerouslySetInnerHTML={{ __html: ICON_TRASH }} />
            <span>삭제</span>
          </button>
        </div>
      </div>
    </div>
  );
}