06계열마다 감쇠로 늦게 자리잡는 멀티시리즈 로딩

<main class="stage">
<div class="cm is-demo" id="cm">
  <svg class="cm__svg" id="cmSvg" viewBox="0 0 200 100" role="img" aria-label="계열 3종 추이 그래프" aria-busy="true">
    <line class="cm__axis" x1="4" y1="92" x2="196" y2="92" />
    <path class="cm__flat" d="M4,60 L196,60" />
    <path class="cm__series" id="cmSeries0" data-i="0" d="M4,70 L44,52 L84,64 L124,34 L164,46 L196,26" />
    <path class="cm__series" id="cmSeries1" data-i="1" d="M4,50 L44,66 L84,40 L124,58 L164,30 L196,44" />
    <path class="cm__series" id="cmSeries2" data-i="2" d="M4,30 L44,38 L84,20 L124,42 L164,18 L196,32" />
  </svg>
  <button type="button" class="cm__reload" id="cmReload">그래프 다시 불러오기</button>
</div>
</main>

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

// 변수 3개
$duration: $dur-loop;
$easing: $ease-out;
$color: $chart-1;

@include stage($stage-ink);

.cm { width: min(300px, 88vw); }
.cm__svg { width: 100%; height: auto; overflow: visible; }
.cm__axis { stroke: rgba($subject-cream, .22); stroke-width: 1; }
.cm__flat {
  fill: none; stroke: rgba($subject-cream, .3); stroke-width: 2; stroke-dasharray: 5 5;
  stroke-linecap: round; animation: cmFlatFade $duration $easing infinite;
}
.cm__series { fill: none; stroke-width: 2.5; stroke-linecap: round; stroke-linejoin: round; animation: cmDraw $duration $easing infinite; }
#cmSeries0 { stroke: $chart-1; }
#cmSeries1 { stroke: $chart-2; }
#cmSeries2 { stroke: $chart-3; }
.cm__reload {
  display: block; margin: $sp-4 auto 0; appearance: none; border: none; cursor: pointer;
  background: rgba($subject-cream, .12); color: $subject-cream; font-weight: 700; font-size: 13px;
  padding: $sp-2 $sp-4; border-radius: $r-pill;
}
.cm__reload:focus-visible { outline: 2px solid $subject-cream; outline-offset: 2px; }

@keyframes cmFlatFade {
  0%   { opacity: 1; }
  8%   { opacity: 1; }
  16%  { opacity: 0; }
  84%  { opacity: 0; }
  94%  { opacity: 1; }
  100% { opacity: 1; }
}

@keyframes cmDraw {
  0%   { stroke-dashoffset: var(--len); }
  10%  { stroke-dashoffset: var(--len); }
  40%  { stroke-dashoffset: 0; }
  84%  { stroke-dashoffset: 0; }
  100% { stroke-dashoffset: var(--len); }
}

@media (max-width: 340px) {
  .cm { width: min(190px, 80vw); }
  .cm__reload { margin-top: $sp-2; font-size: 11px; padding: $sp-1 $sp-3; }
}

@media (prefers-reduced-motion: reduce) {
  // 실사용 경로 적용: 자동 루프를 멈추고 완성된 계열만 보인다
  .cm__flat { animation: none; opacity: 0; }
  .cm__series { animation: none; stroke-dashoffset: 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);
}

.cm {
  width: min(300px, 88vw);
}

.cm__svg {
  width: 100%;
  height: auto;
  overflow: visible;
}

.cm__axis {
  stroke: rgba(255, 247, 230, 0.22);
  stroke-width: 1;
}

.cm__flat {
  fill: none;
  stroke: rgba(255, 247, 230, 0.3);
  stroke-width: 2;
  stroke-dasharray: 5 5;
  stroke-linecap: round;
  animation: cmFlatFade 2s ease-out infinite;
}

.cm__series {
  fill: none;
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
  animation: cmDraw 2s ease-out infinite;
}

#cmSeries0 {
  stroke: #2f6df6;
}

#cmSeries1 {
  stroke: #c2361a;
}

#cmSeries2 {
  stroke: #2b9d74;
}

.cm__reload {
  display: block;
  margin: 16px auto 0;
  appearance: none;
  border: none;
  cursor: pointer;
  background: rgba(255, 247, 230, 0.12);
  color: #fff7e6;
  font-weight: 700;
  font-size: 13px;
  padding: 8px 16px;
  border-radius: 999px;
}

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

@keyframes cmFlatFade {
  0% {
    opacity: 1;
  }
  8% {
    opacity: 1;
  }
  16% {
    opacity: 0;
  }
  84% {
    opacity: 0;
  }
  94% {
    opacity: 1;
  }
  100% {
    opacity: 1;
  }
}
@keyframes cmDraw {
  0% {
    stroke-dashoffset: var(--len);
  }
  10% {
    stroke-dashoffset: var(--len);
  }
  40% {
    stroke-dashoffset: 0;
  }
  84% {
    stroke-dashoffset: 0;
  }
  100% {
    stroke-dashoffset: var(--len);
  }
}
@media (max-width: 340px) {
  .cm {
    width: min(190px, 80vw);
  }
  .cm__reload {
    margin-top: 8px;
    font-size: 11px;
    padding: 4px 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cm__flat {
    animation: none;
    opacity: 0;
  }
  .cm__series {
    animation: none;
    stroke-dashoffset: 0;
  }
}

(function () {
  var STEP_MS = 220;
  var DAMPING = 0.55;
  var root = document.getElementById('cm');
  var reload = document.getElementById('cmReload');
  var series = [0, 1, 2].map(function (i) { return document.getElementById('cmSeries' + i); });

  // 계산 겹: 계열 지연을 감쇠(등비) 누적으로 계산한다 — 뒤 계열일수록 늘어나는 간격이 줄어들며 안정된다
  function seriesDelay(i) {
    var total = 0;
    for (var k = 1; k <= i; k += 1) { total += STEP_MS * Math.pow(DAMPING, k - 1); }
    return Math.round(total);
  }

  series.forEach(function (path, i) {
    var len = Math.round(path.getTotalLength());
    path.style.setProperty('--len', String(len));
    path.style.strokeDasharray = String(len);
    path.style.strokeDashoffset = String(len);
    path.style.animationDelay = seriesDelay(i) + 'ms';
  });

  function human() {
    root.classList.remove('is-demo');
    root.querySelector('#cmSvg').setAttribute('aria-busy', 'true');
    var lastDelay = 0;
    series.forEach(function (path, i) {
      var len = parseInt(path.style.getPropertyValue('--len'), 10);
      path.getAnimations().forEach(function (a) { a.cancel(); });
      path.style.animation = 'none';
      path.style.strokeDashoffset = String(len);
      var delayMs = seriesDelay(i);
      lastDelay = delayMs;
      window.setTimeout(function () {
        path.animate(
          [{ strokeDashoffset: len }, { strokeDashoffset: 0 }],
          { duration: 420, easing: 'ease-out', fill: 'forwards' }
        );
      }, 200 + delayMs);
    });
    window.setTimeout(function () { root.querySelector('#cmSvg').setAttribute('aria-busy', 'false'); }, 200 + lastDelay + 500);
  }

  reload.addEventListener('click', human);
  reload.addEventListener('keydown', function (e) {
    if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); human(); }
  });
}());

import { useEffect, useRef } from 'react';
import styles from './ChartLoadingMultiSeriesCascade.module.scss';

const STEP_MS = 220;
const DAMPING = 0.55;
const PATHS = [
  'M4,70 L44,52 L84,64 L124,34 L164,46 L196,26',
  'M4,50 L44,66 L84,40 L124,58 L164,30 L196,44',
  'M4,30 L44,38 L84,20 L124,42 L164,18 L196,32'
];

export default function ChartLoadingMultiSeriesCascade() {
  const rootRef = useRef<HTMLDivElement>(null);
  const svgRef = useRef<SVGSVGElement>(null);
  const reloadRef = useRef<HTMLButtonElement>(null);
  const seriesRefs = useRef<SVGPathElement[]>([]);

  useEffect(() => {
    const root = rootRef.current;
    const svg = svgRef.current;
    const reload = reloadRef.current;
    if (!root || !svg || !reload) return undefined;
    const series = seriesRefs.current!;
    if (!series || series.length !== PATHS.length) return undefined;

    // 계산 겹: 계열 지연을 감쇠(등비) 누적으로 계산한다 — 뒤 계열일수록 늘어나는 간격이 줄어들며 안정된다
    function seriesDelay(i: number) {
      let total = 0;
      for (let k = 1; k <= i; k += 1) { total += STEP_MS * Math.pow(DAMPING, k - 1); }
      return Math.round(total);
    }

    series.forEach((path, i) => {
      const len = Math.round(path.getTotalLength());
      path.style.setProperty('--len', String(len));
      path.style.strokeDasharray = String(len);
      path.style.strokeDashoffset = String(len);
      path.style.animationDelay = seriesDelay(i) + 'ms';
    });

    const timers: number[] = [];
    function human() {
      root!.classList.remove(styles['is-demo']);
      svg!.setAttribute('aria-busy', 'true');
      let lastDelay = 0;
      series.forEach((path, i) => {
        const len = parseInt(path.style.getPropertyValue('--len'), 10);
        path.getAnimations().forEach((a) => a.cancel());
        path.style.animation = 'none';
        path.style.strokeDashoffset = String(len);
        const delayMs = seriesDelay(i);
        lastDelay = delayMs;
        timers.push(window.setTimeout(() => {
          path.animate(
            [{ strokeDashoffset: len }, { strokeDashoffset: 0 }],
            { duration: 420, easing: 'ease-out', fill: 'forwards' }
          );
        }, 200 + delayMs));
      });
      timers.push(window.setTimeout(() => { svg!.setAttribute('aria-busy', 'false'); }, 200 + lastDelay + 500));
    }

    function onClick() { human(); }
    function onKey(e: KeyboardEvent) { if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); human(); } }
    reload.addEventListener('click', onClick);
    reload.addEventListener('keydown', onKey);

    return () => {
      reload.removeEventListener('click', onClick);
      reload.removeEventListener('keydown', onKey);
      timers.forEach((id) => window.clearTimeout(id));
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.cm + ' ' + styles['is-demo']} ref={rootRef}>
        <svg className={styles.cmSvg} ref={svgRef} viewBox="0 0 200 100" role="img" aria-label="계열 3종 추이 그래프" aria-busy="true">
          <line className={styles.cmAxis} x1={4} y1={92} x2={196} y2={92} />
          <path className={styles.cmFlat} d="M4,60 L196,60" />
          {PATHS.map((d, i) => (
            <path
              key={i}
              id={'cmSeries' + i}
              className={styles.cmSeries}
              data-i={i}
              d={d}
              ref={(el: SVGPathElement | null) => { if (el) seriesRefs.current![i] = el; }}
            />
          ))}
        </svg>
        <button type="button" className={styles.cmReload} ref={reloadRef}>그래프 다시 불러오기</button>
      </div>
    </main>
  );
}