04Password dot morph

<main class="stage">
  <span class="pd-wrap is-demo" aria-label="SECRET">
    <span class="pd-dots">••••••</span>
    <span class="pd-real">SECRET</span>
  </span>
</main>

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

// ── 변수 3개 ──────────────────────────────────────────
$duration: $dur-loop;
$easing: $ease-spring;
$color: $subject-blue;

@include stage($stage-paper);

.pd-wrap {
  position: relative;
  display: inline-block;
  font: 800 clamp(24px, 8vw, 38px)/1.2 "Space Mono", "Courier New", monospace;
  color: $color;
}

.pd-dots { display: block; letter-spacing: .12em; }

.pd-real {
  position: absolute;
  inset: 0;
  opacity: 0;
  transform: scale(.9);
  letter-spacing: .04em;
}

// 데모 루프: 점으로 가려진 글자가 살짝 커지며 크로스페이드로 실제 글자로 바뀐다
@keyframes pd-hide {
  0%, 18% { opacity: 1; transform: scale(1); }
  48%, 100% { opacity: 0; transform: scale(1.08); }
}
@keyframes pd-show {
  0%, 18% { opacity: 0; transform: scale(.9); }
  48%, 78% { opacity: 1; transform: scale(1); }
  100% { opacity: 0; transform: scale(.9); }
}

.pd-wrap.is-demo .pd-dots { animation: pd-hide $duration $easing infinite; }
.pd-wrap.is-demo .pd-real { animation: pd-show $duration $easing infinite; }

@media (prefers-reduced-motion: reduce) {
  .pd-dots, .pd-wrap.is-demo .pd-dots { animation: none !important; opacity: 0 !important; }
  .pd-real, .pd-wrap.is-demo .pd-real { animation: none !important; opacity: 1 !important; transform: none !important; }
}

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

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

.pd-wrap {
  position: relative;
  display: inline-block;
  font: 800 clamp(24px, 8vw, 38px)/1.2 "Space Mono", "Courier New", monospace;
  color: #2f6df6;
}

.pd-dots {
  display: block;
  letter-spacing: 0.12em;
}

.pd-real {
  position: absolute;
  inset: 0;
  opacity: 0;
  transform: scale(0.9);
  letter-spacing: 0.04em;
}

@keyframes pd-hide {
  0%, 18% {
    opacity: 1;
    transform: scale(1);
  }
  48%, 100% {
    opacity: 0;
    transform: scale(1.08);
  }
}
@keyframes pd-show {
  0%, 18% {
    opacity: 0;
    transform: scale(0.9);
  }
  48%, 78% {
    opacity: 1;
    transform: scale(1);
  }
  100% {
    opacity: 0;
    transform: scale(0.9);
  }
}
.pd-wrap.is-demo .pd-dots {
  animation: pd-hide 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.pd-wrap.is-demo .pd-real {
  animation: pd-show 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@media (prefers-reduced-motion: reduce) {
  .pd-dots, .pd-wrap.is-demo .pd-dots {
    animation: none !important;
    opacity: 0 !important;
  }
  .pd-real, .pd-wrap.is-demo .pd-real {
    animation: none !important;
    opacity: 1 !important;
    transform: none !important;
  }
}

import { CSSProperties, useEffect, useRef, useState } from "react";
import styles from "./PasswordDotMorph.module.scss";

export interface PasswordDotMorphProps {
  text?: string;
  duration?: string;
  easing?: string;
}

// 실사용: 뷰포트에 들어오면 비밀번호 점이 살짝 커지며 크로스페이드로 실제 글자로 바뀐다.
export default function PasswordDotMorph({
  text = "SECRET",
  duration = "420ms",
  easing = "cubic-bezier(.2,.8,.2,1)",
}: PasswordDotMorphProps) {
  const ref = useRef<HTMLSpanElement>(null);
  const [revealed, setRevealed] = useState(false);

  useEffect(() => {
    const el = ref.current;
    if (!el) return;
    const io = new IntersectionObserver((entries) => {
      entries.forEach((e) => { if (e.isIntersecting) { setRevealed(true); io.unobserve(e.target); } });
    }, { threshold: 0.3 });
    io.observe(el);
    return () => io.disconnect();
  }, []);

  const style = { "--duration": duration, "--easing": easing } as CSSProperties;

  return (
    <span className={styles.wrap} style={style} ref={ref}>
      <span className={`${styles.dots} ${revealed ? styles.hide : ""}`}>{"•".repeat(text.length)}</span>
      <span className={`${styles.real} ${revealed ? styles.show : ""}`}>{text}</span>
    </span>
  );
}