03Pause/resume state-value switch — the progress value stops changing and starts again each time the state value toggles between paused and running

<main class="stage">
<div class="dpr is-demo" id="dpr">
  <div class="dpr__head">
    <span class="dpr__state" id="dprState">In progress</span>
    <span class="dpr__pct" id="dprPct">0%</span>
  </div>
  <div class="dpr__track"><div class="dpr__fill" id="dprFill"></div></div>
  <button class="dpr__btn" id="dprBtn" type="button">Pause</button>
</div>
</main>

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

// 계산 겹: 경과 시간 = 정지 전 누적값 + (지금 - 재개 시각) — index.html elapsed() 참조
@include stage($stage-orange);

.dpr {
  width: 100%;
  max-width: 240px;
  display: grid;
  gap: $sp-3;
}

.dpr__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  font: 600 14px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: $subject-ink;
}

.dpr--paused .dpr__state { text-decoration: underline; text-decoration-thickness: 2px; }

.dpr__pct { font-variant-numeric: tabular-nums; color: $subject-ink; }

.dpr__track {
  width: 100%;
  height: $sp-3;
  border-radius: $r-pill;
  background: rgba($subject-ink, .16);
  overflow: hidden;
}

.dpr__fill {
  height: 100%;
  width: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  border-radius: $r-pill;
  background: $subject-ink;
}

.dpr--paused .dpr__fill { background: $subject-orange-deep; }

.dpr__btn {
  width: 100%;
  border: 0;
  border-radius: $r-control;
  padding: $sp-2 $sp-4;
  background: $subject-ink;
  color: $subject-cream;
  font: 700 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform $dur-instant $ease-out;

  &:active { transform: scale(.96); }
}

@media (max-width: 340px) {
  .dpr { max-width: 200px; }
}

@media (prefers-reduced-motion: reduce) {
  .dpr__btn { 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);
}

.dpr {
  width: 100%;
  max-width: 240px;
  display: grid;
  gap: 12px;
}

.dpr__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  font: 600 14px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  color: #17141a;
}

.dpr--paused .dpr__state {
  text-decoration: underline;
  text-decoration-thickness: 2px;
}

.dpr__pct {
  font-variant-numeric: tabular-nums;
  color: #17141a;
}

.dpr__track {
  width: 100%;
  height: 12px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.16);
  overflow: hidden;
}

.dpr__fill {
  height: 100%;
  width: 100%;
  transform-origin: left center;
  transform: scaleX(0);
  border-radius: 999px;
  background: #17141a;
}

.dpr--paused .dpr__fill {
  background: #c93000;
}

.dpr__btn {
  width: 100%;
  border: 0;
  border-radius: 12px;
  padding: 8px 16px;
  background: #17141a;
  color: #fff7e6;
  font: 700 13px/1 -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.dpr__btn:active {
  transform: scale(0.96);
}

@media (max-width: 340px) {
  .dpr {
    max-width: 200px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .dpr__btn {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('dpr');
  var state = document.getElementById('dprState');
  var pctEl = document.getElementById('dprPct');
  var fill = document.getElementById('dprFill');
  var btn = document.getElementById('dprBtn');

  // 상수: Total 소요 시간(ms) · 자동 루프의 Stopped 구간(ms)
  var TOTAL_MS = 2600;
  var AUTO_PAUSE_AT = [0.28, 0.62];
  var AUTO_PAUSE_MS = 420;

  var paused = false;
  var startedAt = performance.now();
  var pausedElapsed = 0; // 정지되기 전까지 이미 쌓인 경과 값
  var raf = null;
  var autoIdx = 0;

  // 계산 겹: 경과 시간 = Stopped 전 누적값(pausedElapsed) + (지금 - Resume 시각). 재개할 때 0으로 안 끊긴다
  function elapsed() {
    if (paused) return pausedElapsed;
    return pausedElapsed + (performance.now() - startedAt);
  }

  function paint() {
    var e = Math.min(TOTAL_MS, elapsed());
    var p = e / TOTAL_MS;
    fill.style.transform = 'scaleX(' + p.toFixed(4) + ')';
    pctEl.textContent = Math.round(p * 100) + '%';
    state.textContent = paused ? 'Stopped' : (p >= 1 ? 'Done' : 'In progress');
    root.classList.toggle('dpr--paused', paused && p < 1);
    return p;
  }

  function setPaused(v) {
    if (v === paused) return;
    if (v) {
      pausedElapsed = elapsed();
      paused = true;
    } else {
      startedAt = performance.now();
      paused = false;
    }
  }

  function tick() {
    var p = paint();
    if (!paused && p < 1 && autoIdx < AUTO_PAUSE_AT.length && p >= AUTO_PAUSE_AT[autoIdx]) {
      setPaused(true);
      autoIdx++;
      setTimeout(function () { if (root.classList.contains('is-demo')) setPaused(false); }, AUTO_PAUSE_MS);
    }
    if (p >= 1) {
      setTimeout(function () {
        pausedElapsed = 0; startedAt = performance.now(); paused = false; autoIdx = 0; paint();
      }, 700);
    }
    raf = requestAnimationFrame(tick);
  }
  raf = requestAnimationFrame(tick);

  btn.addEventListener('click', function () {
    root.classList.remove('is-demo');
    setPaused(!paused);
    btn.textContent = paused ? 'Resume' : 'Pause';
  });
})();

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

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

export default function DownloadManagerPauseResume() {
  const rootRef = useRef(null) as unknown as Box<HTMLDivElement | null>;

  useEffect(() => {
    const root = rootRef.current;
    if (!root) return;
    const state = root.querySelector(`.${styles.state}`) as HTMLElement | null;
    const pctEl = root.querySelector(`.${styles.pct}`) as HTMLElement | null;
    const fill = root.querySelector(`.${styles.fill}`) as HTMLElement | null;
    const btn = root.querySelector(`.${styles.btn}`) as HTMLElement | null;
    if (!state || !pctEl || !fill || !btn) return;

    // 상수: 전체 소요 시간(ms) · 자동 루프의 정지 구간(ms)
    const TOTAL_MS = 2600;
    const AUTO_PAUSE_AT = [0.28, 0.62];
    const AUTO_PAUSE_MS = 420;

    let paused = false;
    let startedAt = performance.now();
    let pausedElapsed = 0;
    let raf = 0;
    let autoIdx = 0;
    let stopped = false;

    // 계산 겹: 경과 시간 = 정지 전 누적값(pausedElapsed) + (지금 - 재개 시각). 재개할 때 0으로 안 끊긴다
    function elapsed() {
      if (paused) return pausedElapsed;
      return pausedElapsed + (performance.now() - startedAt);
    }

    function paint() {
      const e = Math.min(TOTAL_MS, elapsed());
      const p = e / TOTAL_MS;
      fill!.style.transform = "scaleX(" + p.toFixed(4) + ")";
      pctEl!.textContent = Math.round(p * 100) + "%";
      state!.textContent = paused ? "정지" : p >= 1 ? "완료" : "진행";
      root!.classList.toggle(styles["dpr--paused"], paused && p < 1);
      return p;
    }

    function setPaused(v: boolean) {
      if (v === paused) return;
      if (v) {
        pausedElapsed = elapsed();
        paused = true;
      } else {
        startedAt = performance.now();
        paused = false;
      }
    }

    function tick() {
      if (stopped) return;
      const p = paint();
      if (!paused && p < 1 && autoIdx < AUTO_PAUSE_AT.length && p >= AUTO_PAUSE_AT[autoIdx]) {
        setPaused(true);
        autoIdx++;
        window.setTimeout(() => { if (root!.classList.contains(styles["is-demo"])) setPaused(false); }, AUTO_PAUSE_MS);
      }
      if (p >= 1) {
        window.setTimeout(() => {
          pausedElapsed = 0; startedAt = performance.now(); paused = false; autoIdx = 0; paint();
        }, 700);
      }
      raf = requestAnimationFrame(tick);
    }
    raf = requestAnimationFrame(tick);

    function onClick() {
      root!.classList.remove(styles["is-demo"]);
      setPaused(!paused);
      btn!.textContent = paused ? "재개" : "일시정지";
    }
    btn.addEventListener("click", onClick);

    return () => {
      stopped = true;
      cancelAnimationFrame(raf);
      btn.removeEventListener("click", onClick);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.stage} ${styles.dpr} ${styles["is-demo"]}`}>
      <div className={styles.head}>
        <span className={styles.state}>진행</span>
        <span className={styles.pct}>0%</span>
      </div>
      <div className={styles.track}><div className={styles.fill} /></div>
      <button className={styles.btn} type="button">일시정지</button>
    </div>
  );
}