01재생 진행률 값으로 그려지는 커스텀 컨트롤 바

<svg width="0" height="0" style="position:absolute" aria-hidden="true">
  <defs>
    <symbol id="ico-play" viewBox="0 0 256 256"><g fill="currentColor"><path d="M228.23 134.69L84.15 222.81A8 8 0 0 1 72 216.12V39.88a8 8 0 0 1 12.15-6.69l144.08 88.12a7.82 7.82 0 0 1 0 13.38" opacity=".2"/><path d="M232.4 114.49L88.32 26.35a16 16 0 0 0-16.2-.3A15.86 15.86 0 0 0 64 39.87v176.26A15.94 15.94 0 0 0 80 232a16.07 16.07 0 0 0 8.36-2.35l144.04-88.14a15.81 15.81 0 0 0 0-27ZM80 215.94V40l143.83 88Z"/></g></symbol>
    <symbol id="ico-pause" viewBox="0 0 256 256"><g fill="currentColor"><path d="M208 48v160a8 8 0 0 1-8 8h-40a8 8 0 0 1-8-8V48a8 8 0 0 1 8-8h40a8 8 0 0 1 8 8M96 40H56a8 8 0 0 0-8 8v160a8 8 0 0 0 8 8h40a8 8 0 0 0 8-8V48a8 8 0 0 0-8-8" opacity=".2"/><path d="M200 32h-40a16 16 0 0 0-16 16v160a16 16 0 0 0 16 16h40a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m0 176h-40V48h40ZM96 32H56a16 16 0 0 0-16 16v160a16 16 0 0 0 16 16h40a16 16 0 0 0 16-16V48a16 16 0 0 0-16-16m0 176H56V48h40Z"/></g></symbol>
  </defs>
</svg>
<main class="stage">
<div class="cp is-demo is-playing" id="cp">
  <p class="cp__hint"><span>재생을 누르면 경과 시간 값으로 손잡이 위치와 남은 시간이 다시 계산됩니다</span></p>
  <div class="cp__panel">
    <div class="cp__title" id="title">Untitled Session</div>
    <div class="cp__row">
      <button class="cp__play" id="play" type="button" aria-label="재생">
        <svg class="cp__ico cp__ico--play" aria-hidden="true"><use href="#ico-play"></use></svg>
        <svg class="cp__ico cp__ico--pause" aria-hidden="true"><use href="#ico-pause"></use></svg>
      </button>
      <div class="cp__seek" id="seek" tabindex="0" role="slider" aria-label="탐색 막대" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0">
        <div class="cp__track" id="track">
          <div class="cp__fill" id="fill"></div>
          <div class="cp__handle" id="handle"></div>
        </div>
      </div>
    </div>
    <div class="cp__time">
      <span id="elapsed">0:00</span>
      <span id="remain">-3:34</span>
    </div>
  </div>
</div>
</main>

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

// 계산 겹(진행률 → 손잡이·채움·시간 텍스트)은 index.html 의 render()/frame() 에 있다. 여기는 무대·레이아웃만.
$duration: $dur-base;
$easing:   $ease-out;
$color:    $subject-sky;

@include stage($stage-ink);

.cp {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-2;
  width: min(400px, 92vw);
}

.cp__hint {
  margin: 0;
  color: rgba($subject-cream, .78);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.35;
  text-align: center;
}

.cp__panel {
  width: 100%;
  border-radius: $r-card;
  background: rgba($subject-cream, .06);
  box-shadow: 0 0 0 1px rgba($subject-cream, .14);
  padding: $sp-6 $sp-5;
  display: flex;
  flex-direction: column;
  gap: $sp-4;
}

.cp__title {
  color: $subject-cream;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .01em;
}

.cp__row {
  display: flex;
  align-items: center;
  gap: $sp-4;
}

.cp__play {
  flex: 0 0 auto;
  width: $sp-10;
  height: $sp-10;
  border-radius: $r-pill;
  border: none;
  background: $color;
  color: $stage-ink;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform $duration $easing;
}

.cp__play:hover { transform: scale(1.06); }
.cp__play:focus-visible { outline: 2px solid $subject-cream; outline-offset: 2px; }
.cp__play:active { transform: scale(.96); }

.cp__ico { width: 18px; height: 18px; }
.cp__ico--pause { display: none; }
.is-playing .cp__ico--play { display: none; }
.is-playing .cp__ico--pause { display: block; }

.cp__seek {
  flex: 1 1 auto;
  padding: $sp-2 0;
  cursor: pointer;
}

.cp__seek:focus-visible {
  outline: 2px solid $subject-cream;
  outline-offset: 4px;
}

.cp__track {
  position: relative;
  height: 4px;
  border-radius: $r-xs;
  background: rgba($subject-cream, .18);
}

.cp__fill {
  position: absolute;
  inset: 0;
  border-radius: $r-xs;
  background: $color;
  transform: scaleX(0);
  transform-origin: left center; // 채움 막대는 왼쪽 기준으로 자라난다 — 진행률의 실제 기준점
}

.cp__handle {
  position: absolute;
  top: 50%;
  left: 0;
  width: $sp-4;
  height: $sp-4;
  margin-top: -$sp-2;
  margin-left: -$sp-2;
  border-radius: $r-pill;
  background: $subject-cream;
  box-shadow: 0 0 0 3px rgba($stage-ink, .5);
}

.cp__time {
  display: flex;
  justify-content: space-between;
  color: rgba($subject-cream, .72);
  font-size: 11px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

@media (max-width: 340px) {
  .cp__panel { padding: $sp-4 $sp-3; }
  .cp__play { width: $sp-8; height: $sp-8; }
  .cp__ico { width: 15px; height: 15px; }
}

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

.cp {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: min(400px, 92vw);
}

.cp__hint {
  margin: 0;
  color: rgba(255, 247, 230, 0.78);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.35;
  text-align: center;
}

.cp__panel {
  width: 100%;
  border-radius: 16px;
  background: rgba(255, 247, 230, 0.06);
  box-shadow: 0 0 0 1px rgba(255, 247, 230, 0.14);
  padding: 24px 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.cp__title {
  color: #fff7e6;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.cp__row {
  display: flex;
  align-items: center;
  gap: 16px;
}

.cp__play {
  flex: 0 0 auto;
  width: 40px;
  height: 40px;
  border-radius: 999px;
  border: none;
  background: #6ec8ff;
  color: #17141a;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: transform 300ms ease-out;
}

.cp__play:hover {
  transform: scale(1.06);
}

.cp__play:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 2px;
}

.cp__play:active {
  transform: scale(0.96);
}

.cp__ico {
  width: 18px;
  height: 18px;
}

.cp__ico--pause {
  display: none;
}

.is-playing .cp__ico--play {
  display: none;
}

.is-playing .cp__ico--pause {
  display: block;
}

.cp__seek {
  flex: 1 1 auto;
  padding: 8px 0;
  cursor: pointer;
}

.cp__seek:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 4px;
}

.cp__track {
  position: relative;
  height: 4px;
  border-radius: 4px;
  background: rgba(255, 247, 230, 0.18);
}

.cp__fill {
  position: absolute;
  inset: 0;
  border-radius: 4px;
  background: #6ec8ff;
  transform: scaleX(0);
  transform-origin: left center;
}

.cp__handle {
  position: absolute;
  top: 50%;
  left: 0;
  width: 16px;
  height: 16px;
  margin-top: -8px;
  margin-left: -8px;
  border-radius: 999px;
  background: #fff7e6;
  box-shadow: 0 0 0 3px rgba(23, 20, 26, 0.5);
}

.cp__time {
  display: flex;
  justify-content: space-between;
  color: rgba(255, 247, 230, 0.72);
  font-size: 11px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

@media (max-width: 340px) {
  .cp__panel {
    padding: 16px 12px;
  }
  .cp__play {
    width: 32px;
    height: 32px;
  }
  .cp__ico {
    width: 15px;
    height: 15px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cp__play {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('cp');
  var playBtn = document.getElementById('play');
  var seek = document.getElementById('seek');
  var track = document.getElementById('track');
  var fill = document.getElementById('fill');
  var handle = document.getElementById('handle');
  var elapsedEl = document.getElementById('elapsed');
  var remainEl = document.getElementById('remain');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var isDemo = true;

  var TRACK_LENGTH_S = 214; // 3:34 — 실 오디오 파일 없음, 합성 트랙 길이 상수
  var SEEK_STEP_S = 5; // 방향키 한 번의 탐색 단위(초)
  var PROGRESS_UPDATE_MS = 200; // 진행률 재계산 주기 — 변형: 이 값을 줄이면 더 잦게 다시 계산해 매끈해진다
  var trackW = 0;

  function fit() {
    var r = track.getBoundingClientRect();
    var hr = handle.getBoundingClientRect();
    trackW = Math.max(1, r.width - hr.width);
  }

  function fmt(sec) {
    sec = Math.max(0, Math.round(sec));
    var m = Math.floor(sec / 60), s = sec % 60;
    return m + ':' + (s < 10 ? '0' : '') + s;
  }

  function render(elapsedS) {
    var p = Math.min(1, Math.max(0, elapsedS / TRACK_LENGTH_S));
    fill.style.transform = 'scaleX(' + p + ')';
    handle.style.transform = 'translateX(' + (p * trackW) + 'px)';
    elapsedEl.textContent = fmt(elapsedS);
    remainEl.textContent = '-' + fmt(TRACK_LENGTH_S - elapsedS);
    seek.setAttribute('aria-valuenow', String(Math.round(p * 100)));
  }

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

  var state = { elapsedS: 0, playing: false, playStart: 0, lastRenderMs: -1 };

  function setPlaying(next) {
    state.playing = next;
    root.classList.toggle('is-playing', next);
    if (next) state.playStart = performance.now() - state.elapsedS * 1000;
  }

  function seekTo(elapsedS) {
    state.elapsedS = Math.min(TRACK_LENGTH_S, Math.max(0, elapsedS));
    if (state.playing) state.playStart = performance.now() - state.elapsedS * 1000;
    render(state.elapsedS);
  }

  function onTrackClick(e) {
    human();
    var r = track.getBoundingClientRect();
    var ratio = (e.clientX - r.left) / r.width;
    seekTo(ratio * TRACK_LENGTH_S);
  }

  function onSeekKeydown(e) {
    if (e.key === 'ArrowRight' || e.key === 'ArrowLeft') {
      e.preventDefault();
      human();
      seekTo(state.elapsedS + (e.key === 'ArrowRight' ? SEEK_STEP_S : -SEEK_STEP_S));
    }
  }

  function onPlayClick() {
    human();
    setPlaying(!state.playing);
  }

  var driveStart = 0;
  function driveTick(now) {
    if (!driveStart) driveStart = now;
    if (isDemo) {
      var DRIVE_PERIOD_MS = 2000; // 렌더 캐처 창(설정 초=2.0)과 같은 주기 — 시연 전용
      var frac = ((now - driveStart) % DRIVE_PERIOD_MS) / DRIVE_PERIOD_MS;
      if (now - state.lastRenderMs >= PROGRESS_UPDATE_MS) {
        render(frac * TRACK_LENGTH_S);
        state.lastRenderMs = now;
      }
    }
    requestAnimationFrame(driveTick);
  }

  function frame(now) {
    if (!isDemo) {
      if (state.playing) {
        var elapsedS = (now - state.playStart) / 1000;
        if (elapsedS >= TRACK_LENGTH_S) { state.playStart = now; elapsedS = 0; }
        state.elapsedS = elapsedS;
      }
      if (now - state.lastRenderMs >= PROGRESS_UPDATE_MS) {
        render(state.elapsedS);
        state.lastRenderMs = now;
      }
    }
    requestAnimationFrame(frame);
  }

  window.addEventListener('resize', fit);
  fit();

  if (reduce) {
    root.classList.add('is-still');
    render(0);
    playBtn.addEventListener('click', function () { human(); setPlaying(!state.playing); render(state.elapsedS); });
    track.addEventListener('click', function (e) { onTrackClick(e); });
    seek.addEventListener('keydown', onSeekKeydown);
  } else {
    playBtn.addEventListener('click', onPlayClick);
    track.addEventListener('click', onTrackClick);
    seek.addEventListener('keydown', onSeekKeydown);
    requestAnimationFrame(frame);
    requestAnimationFrame(driveTick);
  }
})();

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

export default function CustomPlayer() {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const trackRef = useRef<HTMLDivElement | null>(null);
  const fillRef = useRef<HTMLDivElement | null>(null);
  const handleRef = useRef<HTMLDivElement | null>(null);
  const seekRef = useRef<HTMLDivElement | null>(null);
  const playRef = useRef<HTMLButtonElement | null>(null);
  const elapsedRef = useRef<HTMLSpanElement | null>(null);
  const remainRef = useRef<HTMLSpanElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    const track = trackRef.current;
    const fill = fillRef.current;
    const handle = handleRef.current;
    const seek = seekRef.current;
    const playBtn = playRef.current;
    const elapsedEl = elapsedRef.current;
    const remainEl = remainRef.current;
    if (!root || !track || !fill || !handle || !seek || !playBtn || !elapsedEl || !remainEl) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    let isDemo = true;

    const TRACK_LENGTH_S = 214; // 3:34 — 실 오디오 파일 없음, 합성 트랙 길이 상수
    const SEEK_STEP_S = 5; // 방향키 한 번의 탐색 단위(초)
    const PROGRESS_UPDATE_MS = 200; // 진행률 재계산 주기 — 변형: 이 값을 줄이면 더 잦게 다시 계산해 매끈해진다
    let trackW = 0;

    function fit() {
      const r = track!.getBoundingClientRect();
      const hr = handle!.getBoundingClientRect();
      trackW = Math.max(1, r.width - hr.width);
    }

    function fmt(sec: number) {
      sec = Math.max(0, Math.round(sec));
      const m = Math.floor(sec / 60), s = sec % 60;
      return m + ":" + (s < 10 ? "0" : "") + s;
    }

    function render(elapsedS: number) {
      const p = Math.min(1, Math.max(0, elapsedS / TRACK_LENGTH_S));
      fill!.style.transform = "scaleX(" + p + ")";
      handle!.style.transform = "translateX(" + p * trackW + "px)";
      elapsedEl!.textContent = fmt(elapsedS);
      remainEl!.textContent = "-" + fmt(TRACK_LENGTH_S - elapsedS);
      seek!.setAttribute("aria-valuenow", String(Math.round(p * 100)));
    }

    function human() {
      if (isDemo) { root!.classList.remove(styles["is-demo"]); isDemo = false; }
    }

    const state = { elapsedS: 0, playing: false, playStart: 0, lastRenderMs: -1 };

    function setPlaying(next: boolean) {
      state.playing = next;
      root!.classList.toggle(styles["is-playing"], next);
      if (next) state.playStart = performance.now() - state.elapsedS * 1000;
    }

    function seekTo(elapsedS: number) {
      state.elapsedS = Math.min(TRACK_LENGTH_S, Math.max(0, elapsedS));
      if (state.playing) state.playStart = performance.now() - state.elapsedS * 1000;
      render(state.elapsedS);
    }

    function onTrackClick(e: MouseEvent) {
      human();
      const r = track!.getBoundingClientRect();
      const ratio = (e.clientX - r.left) / r.width;
      seekTo(ratio * TRACK_LENGTH_S);
    }

    function onSeekKeydown(e: KeyboardEvent) {
      if (e.key === "ArrowRight" || e.key === "ArrowLeft") {
        e.preventDefault();
        human();
        seekTo(state.elapsedS + (e.key === "ArrowRight" ? SEEK_STEP_S : -SEEK_STEP_S));
      }
    }

    function onPlayClick() { human(); setPlaying(!state.playing); }

    let driveStart = 0;
    let rafDrive = 0;
    function driveTick(now: number) {
      if (!driveStart) driveStart = now;
      if (isDemo) {
        const DRIVE_PERIOD_MS = 2000; // 렌더 캐처 창(설정 초=2.0)과 같은 주기 — 시연 전용
        const frac = ((now - driveStart) % DRIVE_PERIOD_MS) / DRIVE_PERIOD_MS;
        if (now - state.lastRenderMs >= PROGRESS_UPDATE_MS) {
          render(frac * TRACK_LENGTH_S);
          state.lastRenderMs = now;
        }
      }
      rafDrive = requestAnimationFrame(driveTick);
    }

    let rafFrame = 0;
    function frame(now: number) {
      if (!isDemo) {
        if (state.playing) {
          let elapsedS = (now - state.playStart) / 1000;
          if (elapsedS >= TRACK_LENGTH_S) { state.playStart = now; elapsedS = 0; }
          state.elapsedS = elapsedS;
        }
        if (now - state.lastRenderMs >= PROGRESS_UPDATE_MS) {
          render(state.elapsedS);
          state.lastRenderMs = now;
        }
      }
      rafFrame = requestAnimationFrame(frame);
    }

    function onReduceClick() { human(); setPlaying(!state.playing); render(state.elapsedS); }

    window.addEventListener("resize", fit);
    fit();

    if (reduce) {
      root.classList.add(styles["is-still"]);
      render(0);
      playBtn.addEventListener("click", onReduceClick);
      track.addEventListener("click", onTrackClick);
      seek.addEventListener("keydown", onSeekKeydown);
    } else {
      playBtn.addEventListener("click", onPlayClick);
      track.addEventListener("click", onTrackClick);
      seek.addEventListener("keydown", onSeekKeydown);
      rafFrame = requestAnimationFrame(frame);
      rafDrive = requestAnimationFrame(driveTick);
    }

    return () => {
      window.removeEventListener("resize", fit);
      cancelAnimationFrame(rafFrame);
      cancelAnimationFrame(rafDrive);
      if (reduce) {
        playBtn.removeEventListener("click", onReduceClick);
      } else {
        playBtn.removeEventListener("click", onPlayClick);
      }
      track.removeEventListener("click", onTrackClick);
      seek.removeEventListener("keydown", onSeekKeydown);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.cp + ' ' + styles['is-demo'] + ' ' + styles['is-playing']} ref={rootRef}>
        <p className={styles.hint}>
          <span>재생을 누르면 경과 시간 값으로 손잡이 위치와 남은 시간이 다시 계산됩니다</span>
        </p>
        <div className={styles.panel}>
          <div className={styles.title}>Untitled Session</div>
          <div className={styles.row}>
            <button className={styles.play} ref={playRef} type="button" aria-label="재생">
              <svg className={`${styles.ico} ${styles.icoPlay}`} aria-hidden="true"><use href="#ico-play" /></svg>
              <svg className={`${styles.ico} ${styles.icoPause}`} aria-hidden="true"><use href="#ico-pause" /></svg>
            </button>
            <div
              className={styles.seek}
              ref={seekRef}
              tabIndex={0}
              role="slider"
              aria-label="탐색 막대"
              aria-valuemin={0}
              aria-valuemax={100}
              aria-valuenow={0}
            >
              <div className={styles.track} ref={trackRef}>
                <div className={styles.fill} ref={fillRef} />
                <div className={styles.handle} ref={handleRef} />
              </div>
            </div>
          </div>
          <div className={styles.time}>
            <span ref={elapsedRef}>0:00</span>
            <span ref={remainRef}>-3:34</span>
          </div>
        </div>
      </div>
    </main>
  );
}