01カーソル位置固定 — クリックした座標の値がそのままメニューの現れる位置になる方式

<main class="stage">
<div class="cm is-demo" id="cm">
  <div class="cm__field" id="cmField">
    <span class="cm__hint" id="cmHint">右クリック</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 90.34L192 120l-56-56l29.66-29.66a8 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: 클릭 좌표 값을 뷰포트 경계 안으로 clamp 한 뒤 그 값을 그대로 메뉴 위치로 쓴다 (positionAt()).
@include stage($stage-ink);

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

.cm__field {
  width: clamp(180px, 60vw, 260px);
  height: 130px;
  border-radius: $r-card;
  background: $subject-cream;
  color: $subject-ink;
  display: grid;
  place-items: center;
  gap: $sp-1;
  font: 600 14px/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  text-align: center;
  padding: $sp-3;
  box-sizing: border-box;
  user-select: none;
}

.cm__hint { opacity: .7; font-weight: 500; font-size: 12px; }

.cm__menu {
  position: fixed;
  top: 0;
  left: 0;
  min-width: 176px;
  background: $stage-paper;
  border-radius: $r-sm;
  box-shadow: $shadow-raised;
  padding: $sp-1;
  display: grid;
  gap: $sp-1;
  opacity: 0;
  pointer-events: none;
  transition: opacity $dur-quick $ease-out;
  z-index: 5;

  &.is-open { opacity: 1; 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: 148px; }
  .cm__item { padding: $sp-1 $sp-2; font-size: 12px; }
}

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

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  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(180px, 60vw, 260px);
  height: 130px;
  border-radius: 16px;
  background: #fff7e6;
  color: #17141a;
  display: grid;
  place-items: center;
  gap: 4px;
  font: 600 14px/1.3 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  text-align: center;
  padding: 12px;
  box-sizing: border-box;
  user-select: none;
}

.cm__hint {
  opacity: 0.7;
  font-weight: 500;
  font-size: 12px;
}

.cm__menu {
  position: fixed;
  top: 0;
  left: 0;
  min-width: 176px;
  background: #ffffff;
  border-radius: 8px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  padding: 4px;
  display: grid;
  gap: 4px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 220ms ease-out;
  z-index: 5;
}
.cm__menu.is-open {
  opacity: 1;
  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: 148px;
  }
  .cm__item {
    padding: 4px 8px;
    font-size: 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cm__menu {
    transition: none;
  }
}

(function () {
  var field = document.getElementById('cmField');
  var menu = document.getElementById('cmMenu');
  var root = document.getElementById('cm');
  var GAP = 8; // 화면 경계에서 남기는 여백

  function positionAt(x, y) {
    var mw = menu.offsetWidth, mh = menu.offsetHeight;
    var vw = document.documentElement.clientWidth, vh = document.documentElement.clientHeight;
    // 계산 겹: 클릭 좌표 값을 그대로 쓰되, 메뉴 상자가 화면을 벗어나지 않도록 각 축을 독립적으로 clamp 한다.
    var px = Math.max(GAP, Math.min(x, vw - mw - GAP));
    var py = Math.max(GAP, Math.min(y, vh - mh - GAP));
    menu.style.transform = 'translate(' + px.toFixed(0) + 'px,' + py.toFixed(0) + 'px)';
  }

  function open(x, y) {
    positionAt(x, y);
    menu.classList.add('is-open');
  }
  function close() { menu.classList.remove('is-open'); }

  field.addEventListener('contextmenu', function (e) {
    e.preventDefault();
    root.classList.remove('is-demo'); stopAutoplay();
    open(e.clientX, e.clientY);
  });
  document.addEventListener('pointerdown', function (e) {
    if (menu.classList.contains('is-open') && !menu.contains(e.target) && e.target !== field) {
      close();
    }
  });
  menu.addEventListener('click', close);

  // 자동 루프: 클릭 좌표 값이 다른 네 지점(모서리 근처 포함)을 돌며 같은 positionAt() 경로를 탄다.
  var points = [
    { x: 90, y: 86 }, { x: 300, y: 54 }, { x: 56, y: 190 }, { x: 268, y: 214 }
  ];
  var tick = 0, autoTimer = null;
  function autoTick() {
    var step = tick % (points.length * 2);
    if (step % 2 === 0) {
      var p = points[step / 2];
      open(p.x, p.y);
    } else {
      close();
    }
    tick++;
  }
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  function stopAutoplay() { if (autoTimer) { clearInterval(autoTimer); autoTimer = null; } }
  if (!reduce) { autoTimer = setInterval(autoTick, 250); autoTick(); }
})();

import { useEffect, useRef } from "react";
import styles from "./CursorPositionAnchor.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 90.34L192 120l-56-56l29.66-29.66a8 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 CursorPositionAnchorProps = {
  color?: string;
};

export default function CursorPositionAnchor({
  color = "#2f6df6",
}: CursorPositionAnchorProps) {
  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}`);
    if (!field || !menu) return;
    const GAP = 6;

    // 계산 겹: 클릭 좌표를 그대로 앵커로 쓰되, 메뉴 크기와 뷰포트 크기를 재서 넘치는 만큼만
    // 안쪽으로 clamp 한다 — 항상 실제 클릭 지점에서 가장 가까운 안전한 좌표로 붙인다.
    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.transform = `translate(${px.toFixed(0)}px,${py.toFixed(0)}px)`;
    }
    function open(x: number, y: number) {
      positionAt(x, y);
      menu!.classList.add(styles.open);
    }
    function close() { menu!.classList.remove(styles.open); }

    function onContextMenu(e: MouseEvent) {
      e.preventDefault();
      stopAutoplay();
      open(e.clientX, e.clientY);
    }
    function onDocDown(e: PointerEvent) {
      if (menu!.classList.contains(styles.open) && !menu!.contains(e.target as Node) && e.target !== field) close();
    }
    field.addEventListener("contextmenu", onContextMenu);
    document.addEventListener("pointerdown", onDocDown);
    menu.addEventListener("click", close);

    const points = [{ x: 24, y: 20 }, { x: -24, y: 30 }, { x: 0, y: -20 }, { x: 32, y: -10 }];
    let tick = 0;
    let autoTimer: number | null = null;
    function autoTick() {
      const step = tick % (points.length * 2);
      if (step % 2 === 0) {
        const r = field!.getBoundingClientRect();
        const p = points[step / 2];
        open(r.left + r.width / 2 + p.x, r.top + r.height / 2 + p.y);
      } else {
        close();
      }
      tick++;
    }
    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, 250); autoTick(); }

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

  return (
    <div ref={rootRef} className={styles.stage}>
      <div className={styles.cm}>
        <div className={styles.field}>
          <span className={styles.hint}>우클릭</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>
  );
}