04Success morph — on a successful match, the fingerprint icon's path value interpolates smoothly into a checkmark path value

<main class="stage">
<div class="morph-wrap">
<button type="button" class="morph is-demo" id="morph" aria-pressed="false">
  <svg class="morph__icon" viewBox="0 0 120 120" aria-hidden="true">
    <path class="morph__shape" id="shape"></path>
  </svg>
  <span class="morph__label">Auth success</span>
</button>
<p class="morph__status" id="status">Waiting to scan</p>
</div>
</main>

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

// 계산 겹은 index.html 의 buildPath() 에 있다 — 원 점 배열과 체크 점 배열을 진행값 p 로 선형
// 보간해 매 프레임 path d 를 새로 만든다. 여기는 무대·모양만 맡는다.
@include stage($stage-yellow);

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

.morph {
  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-blue-deep; outline-offset: 4px; }
}

.morph__icon {
  width: clamp(120px, 30vw, 160px);
  height: auto;
  overflow: visible;
}

.morph__shape {
  fill: $subject-blue-deep;
  stroke: $stage-ink;
  stroke-width: 1;
  stroke-linejoin: round;
}

.morph__label {
  color: $stage-ink;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.2;
  letter-spacing: .02em;
}

.morph__status {
  margin: 0;
  color: rgba($stage-ink, .6);
  font-weight: 500;
  font-size: 12px;
  line-height: 1.2;
}

@media (max-width: 340px) {
  .stage { padding: $sp-2; }
  .morph-wrap { gap: $sp-2; }
  .morph { padding: $sp-2 $sp-3; gap: $sp-2; }
  .morph__icon { width: 104px; }
  .morph__label { font-size: 12px; }
  .morph__status { font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  .morph__shape { transition: none; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

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

.morph {
  appearance: none;
  border: none;
  background: transparent;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  padding: 16px;
  border-radius: 16px;
}
.morph:focus-visible {
  outline: 2px solid #0a4fe8;
  outline-offset: 4px;
}

.morph__icon {
  width: clamp(120px, 30vw, 160px);
  height: auto;
  overflow: visible;
}

.morph__shape {
  fill: #0a4fe8;
  stroke: #17141a;
  stroke-width: 1;
  stroke-linejoin: round;
}

.morph__label {
  color: #17141a;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.2;
  letter-spacing: 0.02em;
}

.morph__status {
  margin: 0;
  color: rgba(23, 20, 26, 0.6);
  font-weight: 500;
  font-size: 12px;
  line-height: 1.2;
}

@media (max-width: 340px) {
  .stage {
    padding: 8px;
  }
  .morph-wrap {
    gap: 8px;
  }
  .morph {
    padding: 8px 12px;
    gap: 8px;
  }
  .morph__icon {
    width: 104px;
  }
  .morph__label {
    font-size: 12px;
  }
  .morph__status {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .morph__shape {
    transition: none;
  }
}

(function () {
  // 계산 겹: SVG path 모핑 보간 — 원(지문 자리) 점 배열과 체크 점 배열을 같은 점 개수(N)로 두고
  // 진행값 p(0~1) 로 각 점을 선형 보간한 뒤 매 프레임 path d 를 새로 만든다. CSS 트랜지션이 아니라
  // 점 좌표 자체를 계산한다.
  var CX = 60, CY = 60, R = 30;
  var N = 10; // 점 개수 — 두 도형이 같은 개수를 공유해야 보간이 성립한다
  var MORPH_MS = 650; // 원 → 체크 보간에 걸리는 시간
  var HOLD_MS = 550; // 체크 상태 유지 시간
  var GAP_MS = 700; // 다음 자동 성공 시연까지 대기 시간
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var DUR = reduce ? 1 : MORPH_MS;

  var root = document.getElementById('morph');
  var shape = document.getElementById('shape');
  var status = document.getElementById('status');
  var STRINGS = { idle: 'Waiting to scan', done: 'Auth success' };
  var isDemo = true;
  var running = false;
  var startTs = 0;

  function circlePoint(i) {
    var a = (i / N) * Math.PI * 2 - Math.PI / 2;
    return [CX + R * Math.cos(a), CY + R * Math.sin(a)];
  }

  // 체크마크 둘레를 따라 N 개 점을 손으로 배치한다 — 얇은 두 막대가 겹친 다각형
  var CHECK_PTS = [
    [40, 62], [52, 74], [50, 82], [36, 68], [30, 62], [36, 56],
    [50, 68], [82, 36], [88, 42], [58, 78]
  ];

  function lerp(a, b, t) { return a + (b - a) * t; }

  function buildPath(p) {
    var d = '';
    for (var i = 0; i < N; i++) {
      var c = circlePoint(i);
      var k = CHECK_PTS[i];
      var x = lerp(c[0], k[0], p);
      var y = lerp(c[1], k[1], p);
      d += (i === 0 ? 'M' : 'L') + x.toFixed(2) + ',' + y.toFixed(2) + ' ';
    }
    return d + 'Z';
  }

  function apply(p) { shape.setAttribute('d', buildPath(p)); }

  function ease(t) { return 1 - Math.pow(1 - t, 3); }

  function runMorph(ts) {
    if (!startTs) startTs = ts;
    var t = ts - startTs;
    if (t <= DUR) {
      apply(ease(t / DUR));
      status.textContent = STRINGS.idle;
      requestAnimationFrame(runMorph);
    } else if (t <= DUR + HOLD_MS) {
      apply(1);
      status.textContent = STRINGS.done;
      requestAnimationFrame(runMorph);
    } else if (t <= DUR + HOLD_MS + DUR) {
      apply(1 - ease((t - DUR - HOLD_MS) / DUR));
      status.textContent = STRINGS.idle;
      requestAnimationFrame(runMorph);
    } else {
      apply(0);
      running = false;
      root.setAttribute('aria-pressed', 'false');
    }
  }

  function trigger() {
    if (running) return;
    running = true;
    startTs = 0;
    root.setAttribute('aria-pressed', 'true');
    requestAnimationFrame(runMorph);
  }

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

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

  apply(0);

  var cycleStart = 0;
  var PERIOD = DUR * 2 + HOLD_MS + GAP_MS;
  function loop(ts) {
    if (isDemo && !reduce) {
      if (!cycleStart) cycleStart = ts;
      var phase = (ts - cycleStart) % PERIOD;
      if (phase < 16 && !running) trigger();
    }
    requestAnimationFrame(loop);
  }
  requestAnimationFrame(loop);
})();

// SuccessMorph — vanilla 판(run/371/demo/04-biometric-scan-success-morph/index.html) 의 React 포트.
// 계산 겹(SVG path 모핑 보간)은 useEffect 안에 있다: 원 점 배열과 체크 점 배열을 같은 점 개수(N)로
// 두고 진행값 p(0~1) 로 선형 보간해 매 프레임 path d 를 새로 만든다.
import { useEffect, useRef, useState } from "react";
import styles from "./SuccessMorph.module.scss";

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

const STRINGS: Record<string, string> = { idle: "스캔 대기 중", done: "인증 성공" };

const CHECK_PTS: [number, number][] = [
  [40, 62], [52, 74], [50, 82], [36, 68], [30, 62], [36, 56],
  [50, 68], [82, 36], [88, 42], [58, 78],
];

export default function SuccessMorph() {
  const rootRef = useRef(null) as unknown as Box<HTMLButtonElement>;
  const shapeRef = useRef(null) as unknown as Box<SVGPathElement>;
  const [status, setStatus] = useState(STRINGS.idle);
  const [pressed, setPressed] = useState(false);

  useEffect(() => {
    const CX = 60, CY = 60, R = 30;
    const N = 10;
    const MORPH_MS = 650;
    const HOLD_MS = 550;
    const GAP_MS = 700;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const DUR = reduce ? 1 : MORPH_MS;

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

    let isDemo = true;
    let running = false;
    let startTs = 0;
    let rafId = 0;

    function circlePoint(i: number): [number, number] {
      const a = (i / N) * Math.PI * 2 - Math.PI / 2;
      return [CX + R * Math.cos(a), CY + R * Math.sin(a)];
    }

    function lerp(a: number, b: number, t: number) { return a + (b - a) * t; }

    function buildPath(p: number) {
      let d = "";
      for (let i = 0; i < N; i++) {
        const c = circlePoint(i);
        const k = CHECK_PTS[i];
        const x = lerp(c[0], k[0], p);
        const y = lerp(c[1], k[1], p);
        d += (i === 0 ? "M" : "L") + x.toFixed(2) + "," + y.toFixed(2) + " ";
      }
      return d + "Z";
    }

    function apply(p: number) { shape.setAttribute("d", buildPath(p)); }
    function ease(t: number) { return 1 - Math.pow(1 - t, 3); }

    function runMorph(ts: number) {
      if (!startTs) startTs = ts;
      const t = ts - startTs;
      if (t <= DUR) {
        apply(ease(t / DUR));
        setStatus(STRINGS.idle);
        rafId = requestAnimationFrame(runMorph);
      } else if (t <= DUR + HOLD_MS) {
        apply(1);
        setStatus(STRINGS.done);
        rafId = requestAnimationFrame(runMorph);
      } else if (t <= DUR + HOLD_MS + DUR) {
        apply(1 - ease((t - DUR - HOLD_MS) / DUR));
        setStatus(STRINGS.idle);
        rafId = requestAnimationFrame(runMorph);
      } else {
        apply(0);
        running = false;
        setPressed(false);
      }
    }

    function trigger() {
      if (running) return;
      running = true;
      startTs = 0;
      setPressed(true);
      rafId = requestAnimationFrame(runMorph);
    }

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

    apply(0);

    let cycleStart = 0;
    const PERIOD = DUR * 2 + HOLD_MS + GAP_MS;
    function loop(ts: number) {
      if (isDemo && !reduce) {
        if (!cycleStart) cycleStart = ts;
        const phase = (ts - cycleStart) % PERIOD;
        if (phase < 16 && !running) trigger();
      }
      rafId = requestAnimationFrame(loop);
    }
    rafId = requestAnimationFrame(loop);

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

  return (
    <main className={styles.stage}>
      <div className={styles.morphWrap}>
        <button
          type="button"
          className={styles.morph + " " + styles.isDemo}
          ref={rootRef}
          aria-pressed={pressed}
        >
          <svg className={styles.morphIcon} viewBox="0 0 120 120" aria-hidden="true">
            <path className={styles.morphShape} ref={shapeRef} />
          </svg>
          <span className={styles.morphLabel}>인증 성공</span>
        </button>
        <p className={styles.morphStatus}>{status}</p>
      </div>
    </main>
  );
}