05Flip gallery

<main class="stage">
  <ul class="gallery is-demo">
    <li class="tile"><div class="tile__inner">
      <div class="tile__face tile__face--front" aria-hidden="true"></div>
      <div class="tile__face tile__face--back">Photos</div>
    </div></li>
    <li class="tile"><div class="tile__inner">
      <div class="tile__face tile__face--front" aria-hidden="true"></div>
      <div class="tile__face tile__face--back">Videos</div>
    </div></li>
    <li class="tile"><div class="tile__inner">
      <div class="tile__face tile__face--front" aria-hidden="true"></div>
      <div class="tile__face tile__face--back">Docs</div>
    </div></li>
    <li class="tile"><div class="tile__inner">
      <div class="tile__face tile__face--front" aria-hidden="true"></div>
      <div class="tile__face tile__face--back">Music</div>
    </div></li>
  </ul>
</main>

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

// ── 변수 3개 ──────────────────────────────
$duration: $dur-base;                                   // 타일 하나가 뒤집히는 시간
$easing: $ease-out;
$color: $subject-blue-deep;                             // 뒷면(카테고리) 배경 (크림 글자가 얹히므로 진한 파랑)

@include stage($stage-ink);

.gallery {
  display: grid;
  grid-template-columns: repeat(2, 74px);
  gap: $sp-2;
  list-style: none;
  margin: 0;
  padding: 0;
  perspective: 700px;                                     // 격자 전체가 같은 시점을 공유
}
.tile { width: 74px; height: 74px; }
.tile__inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
}
.tile__face {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  border-radius: $r-sm;
  backface-visibility: hidden;                            // 뒤로 넘어간 면 글자가 반전돼 비치지 않게
}
.tile__face--front { background: $subject-cream; }
.tile__face--back  { background: $color; color: $subject-cream; font-weight: 700; font-size: 12px; line-height: 1; font-family: inherit; transform: rotateY(180deg); }

// 4칸이 0.15초씩 시차를 두고 같은 동작을 한다 — 물결처럼 뒤집힌다
.gallery.is-demo .tile:nth-child(1) .tile__inner { animation: flip $dur-loop $easing infinite; }
.gallery.is-demo .tile:nth-child(2) .tile__inner { animation: flip $dur-loop $easing infinite; animation-delay: .15s; }
.gallery.is-demo .tile:nth-child(3) .tile__inner { animation: flip $dur-loop $easing infinite; animation-delay: .3s; }
.gallery.is-demo .tile:nth-child(4) .tile__inner { animation: flip $dur-loop $easing infinite; animation-delay: .45s; }

@keyframes flip {
  0%, 15%  { transform: rotateY(0deg); }
  50%      { transform: rotateY(180deg); }
  85%, 100% { transform: rotateY(360deg); }               // 360 = 0 이라 다음 루프로 튀지 않고 이어진다
}

// ── 접근성: 움직임 줄이기 설정이면 뒷면(정보)에서 고정 ────────────
@media (prefers-reduced-motion: reduce) {
  .gallery.is-demo .tile__inner { animation: none; transform: rotateY(180deg); }
}

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);
}

.gallery {
  display: grid;
  grid-template-columns: repeat(2, 74px);
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
  perspective: 700px;
}

.tile {
  width: 74px;
  height: 74px;
}

.tile__inner {
  position: relative;
  width: 100%;
  height: 100%;
  transform-style: preserve-3d;
}

.tile__face {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  border-radius: 8px;
  backface-visibility: hidden;
}

.tile__face--front {
  background: #fff7e6;
}

.tile__face--back {
  background: #0a4fe8;
  color: #fff7e6;
  font-weight: 700;
  font-size: 12px;
  line-height: 1;
  font-family: inherit;
  transform: rotateY(180deg);
}

.gallery.is-demo .tile:nth-child(1) .tile__inner {
  animation: flip 2s ease-out infinite;
}

.gallery.is-demo .tile:nth-child(2) .tile__inner {
  animation: flip 2s ease-out infinite;
  animation-delay: 0.15s;
}

.gallery.is-demo .tile:nth-child(3) .tile__inner {
  animation: flip 2s ease-out infinite;
  animation-delay: 0.3s;
}

.gallery.is-demo .tile:nth-child(4) .tile__inner {
  animation: flip 2s ease-out infinite;
  animation-delay: 0.45s;
}

@keyframes flip {
  0%, 15% {
    transform: rotateY(0deg);
  }
  50% {
    transform: rotateY(180deg);
  }
  85%, 100% {
    transform: rotateY(360deg);
  }
}
@media (prefers-reduced-motion: reduce) {
  .gallery.is-demo .tile__inner {
    animation: none;
    transform: rotateY(180deg);
  }
}

import type { CSSProperties } from "react";
import styles from "./FlipGallery.module.scss";

export type FlipGalleryProps = {
  duration?: number;
  easing?: string;
  /** 뒷면(카테고리) 배경 */
  color?: string;
  tiles?: string[];
};

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

export default function FlipGallery({
  duration = 2000,
  easing = "ease-out",
  color = "#2f6df6",
  tiles = ["사진", "동영상", "문서", "음악"],
}: FlipGalleryProps) {
  const base: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  return (
    <ul className={styles.gallery}>
      {tiles.map((t, i) => (
        <li key={t} className={styles.tile}>
          <div className={styles.inner} style={{ ...base, "--delay": `${i * 0.15}s` } as Vars}>
            <div className={`${styles.face} ${styles.front}`} aria-hidden="true" />
            <div className={`${styles.face} ${styles.back}`}>{t}</div>
          </div>
        </li>
      ))}
    </ul>
  );
}