05Chart Loading Whose Gridlines Fade In by Distance

<main class="stage">
<div class="cg is-demo" id="cg" role="img" aria-label="Quarterly metrics grid" aria-busy="true">
  <div class="cg__cell" data-row="0" data-col="0"><div class="cg__sk"></div><div class="cg__real" data-v="A"></div></div>
  <div class="cg__cell" data-row="0" data-col="1"><div class="cg__sk"></div><div class="cg__real" data-v="B"></div></div>
  <div class="cg__cell" data-row="0" data-col="2"><div class="cg__sk"></div><div class="cg__real" data-v="C"></div></div>
  <div class="cg__cell" data-row="0" data-col="3"><div class="cg__sk"></div><div class="cg__real" data-v="D"></div></div>
  <div class="cg__cell" data-row="1" data-col="0"><div class="cg__sk"></div><div class="cg__real" data-v="E"></div></div>
  <div class="cg__cell" data-row="1" data-col="1"><div class="cg__sk"></div><div class="cg__real" data-v="F"></div></div>
  <div class="cg__cell" data-row="1" data-col="2"><div class="cg__sk"></div><div class="cg__real" data-v="G"></div></div>
  <div class="cg__cell" data-row="1" data-col="3"><div class="cg__sk"></div><div class="cg__real" data-v="H"></div></div>
  <div class="cg__cell" data-row="2" data-col="0"><div class="cg__sk"></div><div class="cg__real" data-v="I"></div></div>
  <div class="cg__cell" data-row="2" data-col="1"><div class="cg__sk"></div><div class="cg__real" data-v="J"></div></div>
  <div class="cg__cell" data-row="2" data-col="2"><div class="cg__sk"></div><div class="cg__real" data-v="K"></div></div>
  <div class="cg__cell" data-row="2" data-col="3"><div class="cg__sk"></div><div class="cg__real" data-v="L"></div></div>
</div>
<button type="button" class="cg__reload" id="cgReload">Reload grid</button>
</main>

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

// 변수 3개
$duration: $dur-loop;
$easing: $ease-spring;
$color: $chart-2;

@include stage($stage-orange);

.cg {
  width: min(260px, 82vw);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: $sp-2;
}
.cg__cell { position: relative; aspect-ratio: 1; border-radius: $r-sm; overflow: hidden; }
.cg__sk {
  position: absolute; inset: 0; border-radius: inherit;
  background: rgba($subject-cream, .22);
  animation: cgSkeleton $duration $easing infinite;
  animation-delay: var(--delay, 0ms);
}
.cg__real {
  position: absolute; inset: 0; border-radius: inherit;
  background: $color; opacity: 0; transform: scale(.92); transform-origin: center;
  animation: cgReveal $duration $easing infinite;
  animation-delay: var(--delay, 0ms);
}
.cg__reload {
  display: block; margin: $sp-4 auto 0; appearance: none; border: none; cursor: pointer;
  background: rgba($subject-cream, .9); color: $subject-ink; font-weight: 700; font-size: 13px;
  padding: $sp-2 $sp-4; border-radius: $r-pill;
}
.cg__reload:focus-visible { outline: 2px solid $subject-cream; outline-offset: 2px; }

@keyframes cgSkeleton {
  0%   { opacity: 1; }
  16%  { opacity: 1; }
  30%  { opacity: 0; }
  100% { opacity: 0; }
}

@keyframes cgReveal {
  0%   { opacity: 0; transform: scale(.92); }
  16%  { opacity: 0; transform: scale(.92); }
  34%  { opacity: 1; transform: scale(1); }
  90%  { opacity: 1; transform: scale(1); }
  100% { opacity: 0; transform: scale(.92); }
}

@media (max-width: 340px) {
  .cg { width: min(160px, 76vw); gap: $sp-1; }
  .cg__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 칸만 보인다
  .cg__sk { animation: none; opacity: 0; }
  .cg__real { animation: none; opacity: 1; transform: scale(1); }
}

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);
}

.cg {
  width: min(260px, 82vw);
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 8px;
}

.cg__cell {
  position: relative;
  aspect-ratio: 1;
  border-radius: 8px;
  overflow: hidden;
}

.cg__sk {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: rgba(255, 247, 230, 0.22);
  animation: cgSkeleton 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
  animation-delay: var(--delay, 0ms);
}

.cg__real {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: #c2361a;
  opacity: 0;
  transform: scale(0.92);
  transform-origin: center;
  animation: cgReveal 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
  animation-delay: var(--delay, 0ms);
}

.cg__reload {
  display: block;
  margin: 16px auto 0;
  appearance: none;
  border: none;
  cursor: pointer;
  background: rgba(255, 247, 230, 0.9);
  color: #17141a;
  font-weight: 700;
  font-size: 13px;
  padding: 8px 16px;
  border-radius: 999px;
}

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

@keyframes cgSkeleton {
  0% {
    opacity: 1;
  }
  16% {
    opacity: 1;
  }
  30% {
    opacity: 0;
  }
  100% {
    opacity: 0;
  }
}
@keyframes cgReveal {
  0% {
    opacity: 0;
    transform: scale(0.92);
  }
  16% {
    opacity: 0;
    transform: scale(0.92);
  }
  34% {
    opacity: 1;
    transform: scale(1);
  }
  90% {
    opacity: 1;
    transform: scale(1);
  }
  100% {
    opacity: 0;
    transform: scale(0.92);
  }
}
@media (max-width: 340px) {
  .cg {
    width: min(160px, 76vw);
    gap: 4px;
  }
  .cg__reload {
    margin-top: 8px;
    font-size: 11px;
    padding: 4px 12px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cg__sk {
    animation: none;
    opacity: 0;
  }
  .cg__real {
    animation: none;
    opacity: 1;
    transform: scale(1);
  }
}

(function () {
  var STEP_MS = 55;
  var grid = document.getElementById('cg');
  var reload = document.getElementById('cgReload');
  var cells = Array.prototype.slice.call(grid.querySelectorAll('.cg__cell'));

  // 계산 겹: 칸의 (행+열) 대각 거리로 순서를 매긴다 — 왼쪽 위부터 대각선으로 번져 나간다
  function cellOrder(row, col) { return row + col; }

  cells.forEach(function (cell) {
    var row = Number(cell.getAttribute('data-row'));
    var col = Number(cell.getAttribute('data-col'));
    var delay = cellOrder(row, col) * STEP_MS;
    cell.style.setProperty('--delay', delay + 'ms');
  });

  function human() {
    grid.classList.remove('is-demo');
    grid.setAttribute('aria-busy', 'true');
    cells.forEach(function (cell) {
      var sk = cell.querySelector('.cg__sk');
      var real = cell.querySelector('.cg__real');
      sk.style.transition = 'none';
      real.style.transition = 'none';
      sk.style.opacity = '1';
      real.style.opacity = '0';
      real.style.transform = 'scale(.92)';
    });
    var row = 0, col = 0, maxOrder = 0;
    cells.forEach(function (cell) {
      row = Number(cell.getAttribute('data-row'));
      col = Number(cell.getAttribute('data-col'));
      var order = cellOrder(row, col);
      if (order > maxOrder) { maxOrder = order; }
      var delayMs = order * STEP_MS;
      window.setTimeout(function () {
        var sk = cell.querySelector('.cg__sk');
        var real = cell.querySelector('.cg__real');
        sk.style.transition = 'opacity 220ms ease-out';
        real.style.transition = 'opacity 220ms ease-out, transform 220ms ease-out';
        sk.style.opacity = '0';
        real.style.opacity = '1';
        real.style.transform = 'scale(1)';
      }, 200 + delayMs);
    });
    window.setTimeout(function () { grid.setAttribute('aria-busy', 'false'); }, 200 + maxOrder * STEP_MS + 260);
  }

  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 './ChartLoadingGridFadeOrder.module.scss';

const STEP_MS = 55;
const ROWS = 3;
const COLS = 4;
const LABELS = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L'];

export default function ChartLoadingGridFadeOrder() {
  const gridRef = useRef<HTMLDivElement>(null);
  const reloadRef = useRef<HTMLButtonElement>(null);
  const skRefs = useRef<HTMLDivElement[]>([]);
  const realRefs = useRef<HTMLDivElement[]>([]);

  const cells: { row: number; col: number; v: string }[] = [];
  for (let r = 0; r < ROWS; r += 1) {
    for (let c = 0; c < COLS; c += 1) { cells.push({ row: r, col: c, v: LABELS[r * COLS + c] }); }
  }

  useEffect(() => {
    const grid = gridRef.current;
    const reload = reloadRef.current;
    if (!grid || !reload) return undefined;
    const sks = skRefs.current!;
    const reals = realRefs.current!;
    if (!sks || !reals) return undefined;

    // 계산 겹: 칸의 (행+열) 대각 거리로 순서를 매긴다 — 왼쪽 위부터 대각선으로 번져 나간다
    function cellOrder(row: number, col: number) { return row + col; }

    cells.forEach((cell, i) => {
      const delay = cellOrder(cell.row, cell.col) * STEP_MS;
      sks[i].parentElement!.style.setProperty('--delay', delay + 'ms');
    });

    const timers: number[] = [];
    function human() {
      grid!.classList.remove(styles['is-demo']);
      grid!.setAttribute('aria-busy', 'true');
      cells.forEach((_cell, i) => {
        sks[i].style.transition = 'none';
        reals[i].style.transition = 'none';
        sks[i].style.opacity = '1';
        reals[i].style.opacity = '0';
        reals[i].style.transform = 'scale(.92)';
      });
      let maxOrder = 0;
      cells.forEach((cell, i) => {
        const order = cellOrder(cell.row, cell.col);
        if (order > maxOrder) { maxOrder = order; }
        const delayMs = order * STEP_MS;
        timers.push(window.setTimeout(() => {
          sks[i].style.transition = 'opacity 220ms ease-out';
          reals[i].style.transition = 'opacity 220ms ease-out, transform 220ms ease-out';
          sks[i].style.opacity = '0';
          reals[i].style.opacity = '1';
          reals[i].style.transform = 'scale(1)';
        }, 200 + delayMs));
      });
      timers.push(window.setTimeout(() => { grid!.setAttribute('aria-busy', 'false'); }, 200 + maxOrder * STEP_MS + 260));
    }

    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.cg + ' ' + styles['is-demo']} ref={gridRef} role="img" aria-label="분기별 지표 그리드" aria-busy="true">
        {cells.map((cell, i) => (
          <div className={styles.cgCell} data-row={cell.row} data-col={cell.col} key={i}>
            <div className={styles.cgSk} ref={(el: HTMLDivElement | null) => { if (el) skRefs.current![i] = el; }} />
            <div
              className={styles.cgReal}
              data-v={cell.v}
              ref={(el: HTMLDivElement | null) => { if (el) realRefs.current![i] = el; }}
            />
          </div>
        ))}
      </div>
      <button type="button" className={styles.cgReload} ref={reloadRef}>그리드 다시 불러오기</button>
    </main>
  );
}