08Grid-scan glow — the scan area is split into a grid, and each cell glows in turn on its own delay value

<main class="stage">
<div class="grid-wrap">
<button type="button" class="grid is-demo" id="grid" aria-pressed="true">
  <div class="grid__cells" id="cells" aria-hidden="true"></div>
  <span class="grid__label">Fingerprint sensor scan</span>
</button>
<p class="grid__status" id="status">Scanning</p>
</div>
</main>

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

// 계산 겹은 index.html 의 render() 에 있다 — 셀마다 (행+열) 대각 지연을 두고 삼각 펄스를
// 매 프레임 새로 계산해 opacity·transform 만 바꾼다. 여기는 무대·격자 모양만 맡는다.
@include stage($stage-ink);

.grid-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
}

.grid {
  appearance: none;
  border: none;
  background: transparent;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
  cursor: pointer;
  padding: $sp-4;
  border-radius: $r-card;

  &:focus-visible { outline: 2px solid $subject-mint; outline-offset: 4px; }
}

.grid__cells {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 4px;
  padding: $sp-3;
  border-radius: $r-sm;
  background: rgba($subject-mint, .08);
}

.grid__cell {
  width: 18px;
  height: 18px;
  border-radius: $r-xs;
  background: $subject-mint;
  opacity: .16;
  will-change: opacity, transform;
}

.grid__label {
  color: $subject-cream;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.2;
  letter-spacing: .02em;
}

.grid__status {
  margin: 0;
  color: rgba($subject-cream, .68);
  font-weight: 500;
  font-size: 12px;
  line-height: 1.2;
}

@media (max-width: 340px) {
  .stage { padding: $sp-2; }
  .grid-wrap { gap: $sp-2; }
  .grid { padding: $sp-2 $sp-3; gap: $sp-2; }
  .grid__cells { gap: 0; padding: $sp-1; }
  .grid__cell { width: 11px; height: 11px; }
  .grid__label { font-size: 12px; }
  .grid__status { font-size: 11px; }
}

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

.grid-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.grid {
  appearance: none;
  border: none;
  background: transparent;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  padding: 16px;
  border-radius: 16px;
}
.grid:focus-visible {
  outline: 2px solid #4cd4a6;
  outline-offset: 4px;
}

.grid__cells {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 4px;
  padding: 12px;
  border-radius: 8px;
  background: rgba(76, 212, 166, 0.08);
}

.grid__cell {
  width: 18px;
  height: 18px;
  border-radius: 4px;
  background: #4cd4a6;
  opacity: 0.16;
  will-change: opacity, transform;
}

.grid__label {
  color: #fff7e6;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.2;
  letter-spacing: 0.02em;
}

.grid__status {
  margin: 0;
  color: rgba(255, 247, 230, 0.68);
  font-weight: 500;
  font-size: 12px;
  line-height: 1.2;
}

@media (max-width: 340px) {
  .stage {
    padding: 8px;
  }
  .grid-wrap {
    gap: 8px;
  }
  .grid {
    padding: 8px 12px;
    gap: 8px;
  }
  .grid__cells {
    gap: 0;
    padding: 4px;
  }
  .grid__cell {
    width: 11px;
    height: 11px;
  }
  .grid__label {
    font-size: 12px;
  }
  .grid__status {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .grid__cell {
    transition: none;
  }
}

(function () {
  // 계산 겹: 격자 대각 스태거 — 셀마다 (행+열) 로 지연을 매겨 빛이 대각선으로 번져 나간다.
  // delay(row,col) = (row+col)*DIAG_STEP. 지연 목록을 미리 박아두지 않고 매 프레임 셀 좌표에서
  // 직접 계산해 삼각 펄스를 얹는다 — 한 번도 멈추지 않는 진행파라 캡처 구간 어디를 잘라도
  // 항상 움직임이 있다.
  var COLS = 6, ROWS = 6;
  var DIAG_STEP = 90;   // ms, 대각선 한 칸당 지연
  var CYCLE_MS = 1600;  // ms, 파동이 한 바퀴 도는 주기
  var PULSE_MS = 420;   // ms, 셀 하나가 빛나는 지속 시간
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var root = document.getElementById('grid');
  var cellsBox = document.getElementById('cells');
  var status = document.getElementById('status');
  var STRINGS = { on: 'Scanning', off: 'Scan stopped' };
  var isDemo = true;
  var active = true;
  var rafId = 0;
  var startTs = 0;

  var cells = [];
  for (var r = 0; r < ROWS; r++) {
    for (var c = 0; c < COLS; c++) {
      var cell = document.createElement('span');
      cell.className = 'grid__cell';
      cellsBox.appendChild(cell);
      cells.push({ el: cell, diag: r + c });
    }
  }

  function pulse(local) {
    if (local < 0 || local >= PULSE_MS) return 0;
    return Math.sin((local / PULSE_MS) * Math.PI);
  }

  function render(t) {
    for (var i = 0; i < cells.length; i++) {
      var delay = cells[i].diag * DIAG_STEP;
      var local = ((t - delay) % CYCLE_MS + CYCLE_MS) % CYCLE_MS;
      var v = pulse(local);
      cells[i].el.style.opacity = (0.16 + v * 0.84).toFixed(3);
      cells[i].el.style.transform = 'scale(' + (1 + v * 0.22).toFixed(3) + ')';
    }
  }

  function resetCells() {
    for (var i = 0; i < cells.length; i++) {
      cells[i].el.style.opacity = '0.16';
      cells[i].el.style.transform = 'scale(1)';
    }
  }

  function loop(ts) {
    if (!startTs) startTs = ts;
    render(ts - startTs);
    rafId = requestAnimationFrame(loop);
  }

  function setActive(v) {
    active = v;
    root.setAttribute('aria-pressed', String(v));
    status.textContent = v ? STRINGS.on : STRINGS.off;
    cancelAnimationFrame(rafId);
    if (!v) { resetCells(); return; }
    if (reduce) { render(CYCLE_MS * 0.42); return; }
    startTs = 0;
    rafId = requestAnimationFrame(loop);
  }

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

  root.addEventListener('click', function () { human(); setActive(!active); });
  root.addEventListener('keydown', function (e) {
    if (e.key === ' ' || e.key === 'Enter') { human(); }
  });

  setActive(true);
})();

// GridGlow — vanilla 판(run/371/demo/08-biometric-scan-grid-glow/index.html) 의 React 포트.
// 계산 겹(격자 대각 스태거)은 useEffect 안에 있다: 셀마다 (행+열) 로 지연을 매겨 빛이
// 대각선으로 번져 나가는 삼각 펄스를 매 프레임 다시 계산한다 — 지연을 미리 박아두지 않는다.
import { useEffect, useRef, useState } from "react";
import styles from "./GridGlow.module.scss";

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

const COLS = 6, ROWS = 6;
const CELL_COUNT = COLS * ROWS;

export default function GridGlow() {
  const rootRef = useRef(null) as unknown as Box<HTMLButtonElement>;
  const cellsRef = useRef([]) as unknown as Box<(HTMLSpanElement | null)[]>;
  const [status, setStatus] = useState("스캔 중");
  const [pressed, setPressed] = useState(true);

  useEffect(() => {
    const DIAG_STEP = 90;
    const CYCLE_MS = 1600;
    const PULSE_MS = 420;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    const root = rootRef.current;
    if (!root) return;

    const diagOf: number[] = [];
    for (let r = 0; r < ROWS; r++) {
      for (let c = 0; c < COLS; c++) diagOf.push(r + c);
    }

    let isDemo = true;
    let active = true;
    let rafId = 0;
    let startTs = 0;

    function pulse(local: number) {
      if (local < 0 || local >= PULSE_MS) return 0;
      return Math.sin((local / PULSE_MS) * Math.PI);
    }

    function render(t: number) {
      const els = cellsRef.current;
      for (let i = 0; i < els.length; i++) {
        const el = els[i];
        if (!el) continue;
        const delay = diagOf[i] * DIAG_STEP;
        const local = ((t - delay) % CYCLE_MS + CYCLE_MS) % CYCLE_MS;
        const v = pulse(local);
        el.style.opacity = (0.16 + v * 0.84).toFixed(3);
        el.style.transform = "scale(" + (1 + v * 0.22).toFixed(3) + ")";
      }
    }

    function resetCells() {
      const els = cellsRef.current;
      for (let i = 0; i < els.length; i++) {
        const el = els[i];
        if (!el) continue;
        el.style.opacity = "0.16";
        el.style.transform = "scale(1)";
      }
    }

    function loop(ts: number) {
      if (!startTs) startTs = ts;
      render(ts - startTs);
      rafId = requestAnimationFrame(loop);
    }

    function setActive(v: boolean) {
      active = v;
      setPressed(v);
      setStatus(v ? "스캔 중" : "스캔 정지됨");
      cancelAnimationFrame(rafId);
      if (!v) { resetCells(); return; }
      if (reduce) { render(CYCLE_MS * 0.42); return; }
      startTs = 0;
      rafId = requestAnimationFrame(loop);
    }

    function human() { if (isDemo) { root!.classList.remove(styles.isDemo); isDemo = false; } }
    function onClick() { human(); setActive(!active); }
    function onKeyDown(e: KeyboardEvent) { if (e.key === " " || e.key === "Enter") human(); }
    root.addEventListener("click", onClick);
    root.addEventListener("keydown", onKeyDown);

    setActive(true);

    return () => {
      root.removeEventListener("click", onClick);
      root.removeEventListener("keydown", onKeyDown);
      cancelAnimationFrame(rafId);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.gridWrap}>
        <button
          type="button"
          className={styles.grid + " " + styles.isDemo}
          ref={rootRef}
          aria-pressed={pressed}
        >
          <div className={styles.cells} aria-hidden="true">
            {Array.from({ length: CELL_COUNT }).map((_, i) => (
              <span
                key={i}
                className={styles.cell}
                ref={(el: HTMLSpanElement | null) => { cellsRef.current[i] = el; }}
              />
            ))}
          </div>
          <span className={styles.label}>지문 센서 스캔</span>
        </button>
        <p className={styles.status}>{status}</p>
      </div>
    </main>
  );
}