06片方向にだけ引き出る基本スワイプアクション

<main class="stage">
<div class="swa is-demo" id="swa">
  <ul class="swa__list" id="swaList">
    <li class="swa__row">
      <div class="swa__actions"><button type="button" class="swa__actionBtn" data-del>削除</button></div>
      <div class="swa__content" tabindex="0">受信箱のお知らせ1</div>
    </li>
    <li class="swa__row">
      <div class="swa__actions"><button type="button" class="swa__actionBtn" data-del>削除</button></div>
      <div class="swa__content" tabindex="0">受信箱のお知らせ2</div>
    </li>
    <li class="swa__row">
      <div class="swa__actions"><button type="button" class="swa__actionBtn" data-del>削除</button></div>
      <div class="swa__content" tabindex="0">受信箱のお知らせ3</div>
    </li>
  </ul>
</div>
</main>

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

// 변수 3개
$duration: $dur-quick;
$easing: $ease-spring;
$color: $error;

// 계산 겹: index.html 이 손을 뗄 때의 속도(velocity)를 재서, 임계값을 넘으면
// 멈춘 위치와 무관하게 속도의 방향으로 열림/닫힘을 스냅한다.
@include stage($stage-ink);

.swa {
  width: min(100%, 280px);
}

.swa__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: $sp-2;
}

.swa__row {
  position: relative;
  overflow: hidden;
  border-radius: $r-sm;
  transform-origin: top center;

  &.is-deleted {
    animation-name: swaRowOut;
    animation-duration: $dur-base;
    animation-timing-function: $ease-out;
    animation-fill-mode: forwards;
  }
}

@keyframes swaRowOut {
  to { opacity: 0; transform: scaleY(0); }
}

.swa__actions {
  position: absolute;
  inset: 0;
  display: flex;
  justify-content: flex-end;
  align-items: stretch;
  background: rgba($color, .18);
}

.swa__actionBtn {
  box-sizing: border-box;
  width: 72px;
  border: 0;
  background: transparent;
  color: $error;
  font-weight: 700;
  font-size: 12px;
  cursor: pointer;

  &:focus-visible {
    outline: 2px solid $error;
    outline-offset: -2px;
  }
}

.swa__content {
  --swipe-x: 0px;
  box-sizing: border-box;
  position: relative;
  padding: $sp-3;
  border-radius: $r-sm;
  background: rgba(255, 255, 255, .08);
  color: $stage-paper;
  font-weight: 600;
  font-size: 12px;
  transform: translateX(var(--swipe-x));
  transition: transform $duration $easing;
  touch-action: pan-y;

  &.is-dragging {
    transition: none;
  }

  &:focus-visible {
    outline: 2px solid $subject-blue-light;
    outline-offset: 2px;
  }
}

@media (max-width: 340px) {
  .swa__content { padding: $sp-2; font-size: 11px; }
  .swa__actionBtn { width: 60px; font-size: 11px; }
}

// reduce: 실사용 경로 적용 — 스냅 트랜지션과 자동 루프만 멈춘다. 드래그·속도 계산은 그대로 동작
@media (prefers-reduced-motion: reduce) {
  .swa__content { transition: none; }
  .swa__row.is-deleted { animation: none; opacity: 0; }
}

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);
}

.swa {
  width: min(100%, 280px);
}

.swa__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.swa__row {
  position: relative;
  overflow: hidden;
  border-radius: 8px;
  transform-origin: top center;
}
.swa__row.is-deleted {
  animation-name: swaRowOut;
  animation-duration: 300ms;
  animation-timing-function: ease-out;
  animation-fill-mode: forwards;
}

@keyframes swaRowOut {
  to {
    opacity: 0;
    transform: scaleY(0);
  }
}
.swa__actions {
  position: absolute;
  inset: 0;
  display: flex;
  justify-content: flex-end;
  align-items: stretch;
  background: rgba(194, 54, 26, 0.18);
}

.swa__actionBtn {
  box-sizing: border-box;
  width: 72px;
  border: 0;
  background: transparent;
  color: #c2361a;
  font-weight: 700;
  font-size: 12px;
  cursor: pointer;
}
.swa__actionBtn:focus-visible {
  outline: 2px solid #c2361a;
  outline-offset: -2px;
}

.swa__content {
  --swipe-x: 0px;
  box-sizing: border-box;
  position: relative;
  padding: 12px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.08);
  color: #ffffff;
  font-weight: 600;
  font-size: 12px;
  transform: translateX(var(--swipe-x));
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
  touch-action: pan-y;
}
.swa__content.is-dragging {
  transition: none;
}
.swa__content:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 2px;
}

@media (max-width: 340px) {
  .swa__content {
    padding: 8px;
    font-size: 11px;
  }
  .swa__actionBtn {
    width: 60px;
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .swa__content {
    transition: none;
  }
  .swa__row.is-deleted {
    animation: none;
    opacity: 0;
  }
}

(function () {
  var ACTION_WIDTH = 72; // 열렸을 때 드러나는 버튼 폭
  var VELOCITY_OPEN_THRESHOLD = 0.5; // px/ms — 이 속도를 넘기면 위치와 무관하게 방향이 결정된다
  var AUTO_CYCLE_MS = 2000;

  function clamp(v, lo, hi) { return Math.min(hi, Math.max(lo, v)); }

  var root = document.getElementById('swa');
  var list = document.getElementById('swaList');
  var rows = Array.prototype.slice.call(list.querySelectorAll('.swa__row'));
  var rowApis = [];

  rows.forEach(function (row, idx) {
    var content = row.querySelector('.swa__content');
    var delBtn = row.querySelector('[data-del]');
    var dragging = false;
    var startX = 0;
    var baseX = 0;
    var lastX = 0;
    var lastT = 0;
    var velocity = 0;
    var isOpen = false;

    function setX(x, animate) {
      content.style.setProperty('--swipe-x', x.toFixed(1) + 'px');
      content.classList.toggle('is-dragging', !animate);
    }

    function openRow(animate) {
      setX(-ACTION_WIDTH, animate !== false);
      isOpen = true;
      delBtn.tabIndex = 0;
    }

    function closeRow(animate) {
      setX(0, animate !== false);
      isOpen = false;
      delBtn.tabIndex = -1;
    }
    closeRow(false);

    function currentX() {
      var v = content.style.getPropertyValue('--swipe-x');
      return v ? parseFloat(v) : 0;
    }

    content.addEventListener('pointerdown', function (e) {
      human();
      rowApis.forEach(function (api, otherIdx) { if (otherIdx !== idx) { api.close(true); } });
      dragging = true;
      startX = e.clientX;
      baseX = currentX();
      lastX = e.clientX;
      lastT = performance.now();
      velocity = 0;
      content.setPointerCapture(e.pointerId);
    });

    content.addEventListener('pointermove', function (e) {
      if (!dragging) { return; }
      var now = performance.now();
      var dt = Math.max(now - lastT, 1);
      velocity = (e.clientX - lastX) / dt; // px/ms, 음수 = 왼쪽으로 밀리는 중
      lastX = e.clientX;
      lastT = now;
      var raw = baseX + (e.clientX - startX);
      setX(clamp(raw, -ACTION_WIDTH, 0), false);
    });

    content.addEventListener('pointerup', function () {
      if (!dragging) { return; }
      dragging = false;
      // 계산 겹: 손을 뗄 때의 속도가 임계값을 넘으면, 멈춘 위치와 무관하게
      // 속도의 방향이 열림/닫힘을 결정한다. 느리면 위치 절반 기준으로 결정한다.
      var openDecision;
      if (velocity < -VELOCITY_OPEN_THRESHOLD) {
        openDecision = true;
      } else if (velocity > VELOCITY_OPEN_THRESHOLD) {
        openDecision = false;
      } else {
        openDecision = currentX() < -ACTION_WIDTH / 2;
      }
      if (openDecision) { openRow(); } else { closeRow(); }
    });

    delBtn.tabIndex = -1;
    delBtn.addEventListener('click', function () {
      human();
      row.classList.add('is-deleted');
    });

    rowApis.push({ open: openRow, close: closeRow });
  });

  function human() {
    if (root.classList.contains('is-demo')) {
      root.classList.remove('is-demo');
      if (timer) { window.clearInterval(timer); timer = null; }
    }
  }

  var timer = null;
  var start = 0;

  function autoApply() {
    var elapsed = performance.now() - start;
    var phase = (elapsed % AUTO_CYCLE_MS) / AUTO_CYCLE_MS;
    var x;
    if (phase < 0.35) {
      x = -ACTION_WIDTH * (phase / 0.35);
    } else if (phase < 0.65) {
      x = -ACTION_WIDTH;
    } else if (phase < 0.85) {
      x = -ACTION_WIDTH * (1 - (phase - 0.65) / 0.2);
    } else {
      x = 0;
    }
    var content = rows[0].querySelector('.swa__content');
    content.classList.add('is-dragging');
    content.style.setProperty('--swipe-x', x.toFixed(1) + 'px');
  }

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (!reduce) {
    start = performance.now();
    timer = window.setInterval(autoApply, 40);
  } else {
    // reduce: 실사용 경로 적용 — 자동 스와이프 루프를 멈추고 닫힌 상태를 고정으로 보여준다
  }
})();

// SwipeActions — vanilla 판(run/381/demo/06-swipe-actions/index.html)의 React 포트.
// 손을 뗄 때의 속도(velocity = 이동거리/경과시간)가 임계값을 넘으면 멈춘 위치와 무관하게
// 속도의 방향이 열림/닫힘을 결정한다 — 짧고 빠른 스와이프도 인식하는 실제 동작이다.
import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./SwipeActions.module.scss";

export type SwipeActionsProps = {
  duration?: string;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

const LABELS = ["받은편지함 안내 1", "받은편지함 안내 2", "받은편지함 안내 3"];

export default function SwipeActions({
  duration = "220ms", // vanilla $duration: $dur-quick
  easing = "cubic-bezier(.2, .8, .2, 1)", // vanilla $easing: $ease-spring
  color = "#c2361a", // vanilla $color: $error
}: SwipeActionsProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const list = root.querySelector<HTMLUListElement>('[data-role="list"]');
    if (!list) return;
    const rows = Array.prototype.slice.call(list.querySelectorAll("[data-row]")) as HTMLLIElement[];

    const ACTION_WIDTH = 72; // 열렸을 때 드러나는 버튼 폭
    const VELOCITY_OPEN_THRESHOLD = 0.5; // px/ms — 이 속도를 넘기면 위치와 무관하게 방향이 결정된다
    const AUTO_CYCLE_MS = 2000;

    function clamp(v: number, lo: number, hi: number): number {
      return Math.min(hi, Math.max(lo, v));
    }

    function human(): void {
      if (root!.classList.contains("is-demo")) {
        root!.classList.remove("is-demo");
        if (timer) {
          window.clearInterval(timer);
          timer = null;
        }
      }
    }

    type RowApi = { open: (animate?: boolean) => void; close: (animate?: boolean) => void };
    const rowApis: RowApi[] = [];
    const cleanups: (() => void)[] = [];

    rows.forEach((row, idx) => {
      const content = row.querySelector<HTMLDivElement>('[data-role="content"]')!;
      const delBtn = row.querySelector<HTMLButtonElement>("[data-del]")!;

      let dragging = false;
      let startX = 0;
      let baseX = 0;
      let lastX = 0;
      let lastT = 0;
      let velocity = 0;

      function setX(x: number, animate: boolean): void {
        content.style.setProperty("--swipe-x", x.toFixed(1) + "px");
        content.classList.toggle("is-dragging", !animate);
      }

      function currentX(): number {
        const v = content.style.getPropertyValue("--swipe-x");
        return v ? parseFloat(v) : 0;
      }

      function openRow(animate?: boolean): void {
        setX(-ACTION_WIDTH, animate !== false);
        delBtn.tabIndex = 0;
      }
      function closeRow(animate?: boolean): void {
        setX(0, animate !== false);
        delBtn.tabIndex = -1;
      }
      closeRow(false);
      delBtn.tabIndex = -1;

      const rowApi: RowApi = { open: openRow, close: closeRow };
      rowApis.push(rowApi);

      function onPointerDown(e: PointerEvent): void {
        human();
        rowApis.forEach((api, otherIdx) => {
          if (otherIdx !== idx) api.close(true);
        });
        dragging = true;
        startX = e.clientX;
        baseX = currentX();
        lastX = e.clientX;
        lastT = performance.now();
        velocity = 0;
        content.setPointerCapture(e.pointerId);
      }
      function onPointerMove(e: PointerEvent): void {
        if (!dragging) return;
        const now = performance.now();
        const dt = Math.max(now - lastT, 1);
        velocity = (e.clientX - lastX) / dt; // px/ms, 음수 = 왼쪽으로 밀리는 중
        lastX = e.clientX;
        lastT = now;
        const raw = baseX + (e.clientX - startX);
        setX(clamp(raw, -ACTION_WIDTH, 0), false);
      }
      function onPointerUp(): void {
        if (!dragging) return;
        dragging = false;
        // 계산 겹: 손을 뗄 때의 속도가 임계값을 넘으면, 멈춘 위치와 무관하게
        // 속도의 방향이 열림/닫힘을 결정한다. 느리면 위치 절반 기준으로 결정한다.
        let openDecision: boolean;
        if (velocity < -VELOCITY_OPEN_THRESHOLD) {
          openDecision = true;
        } else if (velocity > VELOCITY_OPEN_THRESHOLD) {
          openDecision = false;
        } else {
          openDecision = currentX() < -ACTION_WIDTH / 2;
        }
        if (openDecision) openRow();
        else closeRow();
      }
      content.addEventListener("pointerdown", onPointerDown);
      content.addEventListener("pointermove", onPointerMove);
      content.addEventListener("pointerup", onPointerUp);

      function onDelClick(): void {
        human();
        row.classList.add("is-deleted");
      }
      delBtn.addEventListener("click", onDelClick);

      cleanups.push(() => {
        content.removeEventListener("pointerdown", onPointerDown);
        content.removeEventListener("pointermove", onPointerMove);
        content.removeEventListener("pointerup", onPointerUp);
        delBtn.removeEventListener("click", onDelClick);
      });
    });

    let timer: number | null = null;
    let start = 0;

    // 계산 겹: 2초 주기를 네 구간(진입 35%·유지 30%·복귀 20%·대기 15%)의 조각 선형 함수로 나눠
    // 첫 행이 실제 드래그처럼 열렸다 닫히는 것을 자동 재생으로 보여준다.
    function autoApply(): void {
      const elapsed = performance.now() - start;
      const phase = (elapsed % AUTO_CYCLE_MS) / AUTO_CYCLE_MS;
      let x: number;
      if (phase < 0.35) {
        x = -ACTION_WIDTH * (phase / 0.35);
      } else if (phase < 0.65) {
        x = -ACTION_WIDTH;
      } else if (phase < 0.85) {
        x = -ACTION_WIDTH * (1 - (phase - 0.65) / 0.2);
      } else {
        x = 0;
      }
      const content = rows[0]?.querySelector<HTMLDivElement>('[data-role="content"]');
      if (!content) return;
      content.classList.add("is-dragging");
      content.style.setProperty("--swipe-x", x.toFixed(1) + "px");
    }

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (!reduce) {
      start = performance.now();
      timer = window.setInterval(autoApply, 40);
    }
    // reduce: 실사용 경로 적용 — 자동 스와이프 루프를 멈추고 닫힌 상태를 고정으로 보여준다

    return () => {
      cleanups.forEach((fn) => fn());
      if (timer) {
        window.clearInterval(timer);
      }
    };
  }, []);

  const vars: Vars = { "--duration": duration, "--easing": easing, "--color": color };

  return (
    <main className={styles.stage}>
      <div className={`${styles.swa} is-demo`} ref={rootRef} style={vars}>
        <ul className={styles.swa__list} data-role="list">
          {LABELS.map((label, i) => (
            <li className={styles.swa__row} data-row={i} key={i}>
              <div className={styles.swa__actions}>
                <button type="button" data-del className={styles.swa__actionBtn}>
                  삭제
                </button>
              </div>
              <div className={styles.swa__content} data-role="content" tabIndex={0}>
                {label}
              </div>
            </li>
          ))}
        </ul>
      </div>
    </main>
  );
}