09Touch-device fallback

<main class="stage">
  <div class="panel panel--mouse is-demo">
    <div class="cursor" aria-hidden="true"></div>
    <span class="label">Mouse detected</span>
  </div>
  <div class="panel panel--touch is-demo">
    <button class="tap" type="button">Tap here</button>
    <span class="label">Touch detected</span>
  </div>
</main>

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

$duration: $dur-loop;                                 // 두 패널이 교차하는 한 바퀴
$easing: $ease-spring;
$color: $subject-blue;                                 // 커서 점 색

@include stage($stage-ink);

.stage { position: relative; overflow: hidden; }

.panel {
  position: absolute;
  inset: clamp(14px, 4vw, 24px);
  display: grid;
  place-items: center;
  gap: clamp(8px, 2.4vw, 12px);
  border-radius: $r-card;
  background: rgba(255, 255, 255, .06);
  opacity: 0;
}

.label {
  font-weight: 700; font-size: clamp(12px, 3.4vw, 15px); line-height: 1; font-family: inherit;
  color: $subject-cream;
}

.cursor {
  position: absolute;
  top: 0;
  left: 0;
  width: 14px;
  height: 14px;
  margin: -7px 0 0 -7px;
  border-radius: 50%;
  background: $color;
  pointer-events: none;
}

.tap {
  border: 0;
  border-radius: $r-pill;
  padding: clamp(10px, 3vw, 14px) clamp(22px, 6vw, 30px);
  font-weight: 700; font-size: clamp(13px, 3.6vw, 16px); line-height: 1; font-family: inherit;
  color: $stage-ink;
  background: $subject-cream;
}

.panel--mouse.is-demo { animation: panel-cross $duration $easing infinite; }
.panel--touch.is-demo { animation: panel-cross $duration $easing infinite; animation-delay: calc(#{$duration} / -2); }

@keyframes panel-cross {
  0%   { opacity: 1; }
  50%  { opacity: 0; }
  100% { opacity: 1; }
}

// 마우스 패널의 점은 pointer:fine 실제 기기에서만 움직인다 (JS 가 담당). 여기선 시각 기준점만 둔다.
.panel--mouse .cursor { transform: translate(50%, 50%); }

// 실사용에서는 이 미디어쿼리 하나가 실제 폴백이다 — 터치 기기는 처음부터 터치 패널만 보인다
@media (pointer: coarse) {
  .panel--mouse { display: none; }
  .panel--touch { opacity: 1; animation: none; }
}

@media (prefers-reduced-motion: reduce) {
  .panel.is-demo { animation: none; }
  .panel--mouse.is-demo { opacity: 1; }
  .panel--touch.is-demo { opacity: 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);
}

.stage {
  position: relative;
  overflow: hidden;
}

.panel {
  position: absolute;
  inset: clamp(14px, 4vw, 24px);
  display: grid;
  place-items: center;
  gap: clamp(8px, 2.4vw, 12px);
  border-radius: 16px;
  background: rgba(255, 255, 255, 0.06);
  opacity: 0;
}

.label {
  font-weight: 700;
  font-size: clamp(12px, 3.4vw, 15px);
  line-height: 1;
  font-family: inherit;
  color: #fff7e6;
}

.cursor {
  position: absolute;
  top: 0;
  left: 0;
  width: 14px;
  height: 14px;
  margin: -7px 0 0 -7px;
  border-radius: 50%;
  background: #2f6df6;
  pointer-events: none;
}

.tap {
  border: 0;
  border-radius: 999px;
  padding: clamp(10px, 3vw, 14px) clamp(22px, 6vw, 30px);
  font-weight: 700;
  font-size: clamp(13px, 3.6vw, 16px);
  line-height: 1;
  font-family: inherit;
  color: #17141a;
  background: #fff7e6;
}

.panel--mouse.is-demo {
  animation: panel-cross 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.panel--touch.is-demo {
  animation: panel-cross 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
  animation-delay: calc(2s / -2);
}

@keyframes panel-cross {
  0% {
    opacity: 1;
  }
  50% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}
.panel--mouse .cursor {
  transform: translate(50%, 50%);
}

@media (pointer: coarse) {
  .panel--mouse {
    display: none;
  }
  .panel--touch {
    opacity: 1;
    animation: none;
  }
}
@media (prefers-reduced-motion: reduce) {
  .panel.is-demo {
    animation: none;
  }
  .panel--mouse.is-demo {
    opacity: 1;
  }
  .panel--touch.is-demo {
    opacity: 0;
  }
}

// pointer:fine 인 실제 기기에서만 점이 포인터를 따라간다. 나머지는 @media (pointer: coarse) 가 CSS로 대체한다.
if (matchMedia('(pointer: fine)').matches) {
  var stage = document.querySelector('.stage'), dot = document.querySelector('.cursor');
  stage.addEventListener('pointermove', function (e) {
    var r = stage.getBoundingClientRect();
    dot.style.transform = 'translate(' + (e.clientX - r.left) + 'px,' + (e.clientY - r.top) + 'px)';
  });
}

import { useState } from "react";
import type { CSSProperties, PointerEvent } from "react";
import styles from "./TouchFallbackCursor.module.scss";

export type TouchFallbackCursorProps = {
  mouseLabel?: string;
  touchLabel?: string;
  tapLabel?: string;
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function TouchFallbackCursor({
  mouseLabel = "마우스 감지",
  touchLabel = "터치 감지",
  tapLabel = "탭하세요",
  duration = 2000,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
}: TouchFallbackCursorProps) {
  const [pos, setPos] = useState({ x: 50, y: 50 });

  const move = (e: PointerEvent<HTMLDivElement>) => {
    const r = e.currentTarget.getBoundingClientRect();
    setPos({ x: e.clientX - r.left, y: e.clientY - r.top });
  };

  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  return (
    <div className={styles.stage} style={vars} onPointerMove={move}>
      <div className={`${styles.panel} ${styles.panelMouse} ${styles.isDemo}`}>
        <div className={styles.cursor} style={{ transform: `translate(${pos.x}px,${pos.y}px)` }} aria-hidden="true" />
        <span className={styles.label}>{mouseLabel}</span>
      </div>
      <div className={`${styles.panel} ${styles.panelTouch} ${styles.isDemo}`}>
        <button className={styles.tap} type="button">{tapLabel}</button>
        <span className={styles.label}>{touchLabel}</span>
      </div>
    </div>
  );
}