06Instagram post embed card — a loading gradient whose angle keeps being recomputed

<main class="stage">
<div class="card">
  <div class="topBar">
    <canvas class="avatar" id="avatar" width="64" height="64"></canvas>
    <span class="handle">channel.a</span>
    <span class="follow">Follow</span>
  </div>
  <div class="slot" id="slot">
    <div class="shimmer" id="shimmer" aria-hidden="true"></div>
  </div>
  <div class="bottomRow">
    <svg class="heartIcon" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor">
      <path d="M232 102c0 66-104 122-104 122S24 168 24 102a54 54 0 0 1 54-54c22.59 0 41.94 12.31 50 32c8.06-19.69 27.41-32 50-32a54 54 0 0 1 54 54" opacity=".2"/>
      <path d="M178 40c-20.65 0-38.73 8.88-50 23.89C116.73 48.88 98.65 40 78 40a62.07 62.07 0 0 0-62 62c0 70 103.79 126.66 108.21 129a8 8 0 0 0 7.58 0C136.21 228.66 240 172 240 102a62.07 62.07 0 0 0-62-62m-50 174.8c-18.26-10.64-96-59.11-96-112.8a46.06 46.06 0 0 1 46-46c19.45 0 35.78 10.36 42.6 27a8 8 0 0 0 14.8 0c6.82-16.67 23.15-27 42.6-27a46.06 46.06 0 0 1 46 46c0 53.61-77.76 102.15-96 112.8"/>
    </g></svg>
    <span class="likeLabel">128 likes</span>
    <span class="caption">New post preview</span>
  </div>
</div>
<div class="readout" id="readout">Angle 214°</div>
</main>

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

// 사각 카드 임베드 — 그라디언트 회전각(계산 겹)과 shimmer 이동이 JS 계산 겹의 재료.
// CSS keyframes 는 두지 않는다 — 전부 rAF 실시간 루프.

@include stage($stage-yellow);

.stage {
  overflow: hidden;
}

.card {
  display: flex;
  flex-direction: column;
  width: 220px;
  border-radius: $r-card;
  background: $stage-paper;
  box-shadow: $shadow-raised;
  overflow: hidden;
}

.topBar {
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-2 $sp-3;
}

.avatar {
  display: block;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  flex-shrink: 0;
}

.handle {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 700;
  font-size: 12px;
  line-height: 1.3;
  color: $subject-ink;
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: clip;
  white-space: nowrap;
}

.follow {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.3;
  color: $subject-blue-deep;
  flex-shrink: 0;
}

.slot {
  position: relative;
  height: 120px;
  overflow: hidden;
  --spin: 0deg;
  background: linear-gradient(var(--spin), $subject-pink, $subject-sky, $subject-lilac);
}

.shimmer {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 40%;
  background: linear-gradient(
    90deg,
    rgba(255, 247, 230, 0) 0%,
    rgba(255, 247, 230, .38) 50%,
    rgba(255, 247, 230, 0) 100%
  );
  pointer-events: none;
}

.bottomRow {
  display: flex;
  align-items: center;
  gap: $sp-2;
  padding: $sp-2 $sp-3;
}

.heartIcon {
  width: 18px;
  height: 18px;
  display: block;
  flex-shrink: 0;
}

.heartIcon path {
  fill: $subject-pink;
}

.likeLabel {
  font-family: "Space Mono", ui-monospace, monospace;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.3;
  color: $subject-ink;
  flex-shrink: 0;
}

.caption {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
  color: $subject-ink;
  opacity: .72;
  overflow: hidden;
  text-overflow: clip;
  white-space: nowrap;
  min-width: 0;
}

.readout {
  margin-top: $sp-3;
  display: inline-flex;
  align-items: center;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: $subject-cream;
  font-family: "Space Mono", ui-monospace, monospace;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.3;
  color: $subject-ink;
}

@media (max-width: 340px) {
  .card {
    width: 156px;
  }
  .slot {
    height: 64px;
  }
  .topBar {
    padding: $sp-1 $sp-2;
  }
  .avatar {
    width: 22px;
    height: 22px;
  }
  .bottomRow {
    padding: $sp-1 $sp-2;
  }
  .handle {
    font-size: 11px;
  }
  .caption {
    font-size: 10px;
  }
  .readout {
    font-size: 10px;
    padding: $sp-1 $sp-2;
    margin-top: $sp-2;
  }
}

@media (prefers-reduced-motion: reduce) {
  .shimmer {
    opacity: 0;
  }
}

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);
}

.stage {
  overflow: hidden;
}

.card {
  display: flex;
  flex-direction: column;
  width: 220px;
  border-radius: 16px;
  background: #ffffff;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
}

.topBar {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
}

.avatar {
  display: block;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  flex-shrink: 0;
}

.handle {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 700;
  font-size: 12px;
  line-height: 1.3;
  color: #17141a;
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: clip;
  white-space: nowrap;
}

.follow {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.3;
  color: #0a4fe8;
  flex-shrink: 0;
}

.slot {
  position: relative;
  height: 120px;
  overflow: hidden;
  --spin: 0deg;
  background: linear-gradient(var(--spin), #ff9ebb, #6ec8ff, #b9a0ff);
}

.shimmer {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 40%;
  background: linear-gradient(90deg, rgba(255, 247, 230, 0) 0%, rgba(255, 247, 230, 0.38) 50%, rgba(255, 247, 230, 0) 100%);
  pointer-events: none;
}

.bottomRow {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
}

.heartIcon {
  width: 18px;
  height: 18px;
  display: block;
  flex-shrink: 0;
}

.heartIcon path {
  fill: #ff9ebb;
}

.likeLabel {
  font-family: "Space Mono", ui-monospace, monospace;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.3;
  color: #17141a;
  flex-shrink: 0;
}

.caption {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
  color: #17141a;
  opacity: 0.72;
  overflow: hidden;
  text-overflow: clip;
  white-space: nowrap;
  min-width: 0;
}

.readout {
  margin-top: 12px;
  display: inline-flex;
  align-items: center;
  padding: 4px 12px;
  border-radius: 999px;
  background: #fff7e6;
  font-family: "Space Mono", ui-monospace, monospace;
  font-weight: 700;
  font-size: 11px;
  line-height: 1.3;
  color: #17141a;
}

@media (max-width: 340px) {
  .card {
    width: 156px;
  }
  .slot {
    height: 64px;
  }
  .topBar {
    padding: 4px 8px;
  }
  .avatar {
    width: 22px;
    height: 22px;
  }
  .bottomRow {
    padding: 4px 8px;
  }
  .handle {
    font-size: 11px;
  }
  .caption {
    font-size: 10px;
  }
  .readout {
    font-size: 10px;
    padding: 4px 8px;
    margin-top: 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .shimmer {
    opacity: 0;
  }
}

// 사각 카드 임베드(06) — 이미지 자리는 각도가 도는 그라디언트(계산 겹)로 채우고,
// 그 위를 옅은 띠(shimmer)가 가로질러 로딩 느낌을 더한다. 실키·실서버 요청 없음.
(function () {
  function mulberry32(seed) {
    var a = seed >>> 0;
    return function () {
      a |= 0; a = (a + 0x6D2B79F5) | 0;
      var t = Math.imul(a ^ (a >>> 15), 1 | a);
      t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
      return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
    };
  }
  function drawSeedThumb(canvas, seed) {
    var ctx = canvas.getContext('2d');
    if (!ctx) return;
    var rnd = mulberry32(seed);
    var w = canvas.width, h = canvas.height;
    var hues = [216, 32, 268, 168];
    ctx.fillStyle = 'hsl(' + hues[Math.floor(rnd() * hues.length)] + ', 38%, 22%)';
    ctx.fillRect(0, 0, w, h);
    for (var i = 0; i < 6; i++) {
      var cx = rnd() * w, cy = rnd() * h, r = (0.18 + rnd() * 0.3) * Math.min(w, h);
      ctx.fillStyle = 'hsla(' + hues[Math.floor(rnd() * hues.length)] + ', ' + (44 + rnd() * 22).toFixed(1) + '%, ' + (38 + rnd() * 26).toFixed(1) + '%, .5)';
      ctx.beginPath(); ctx.arc(cx, cy, r, 0, Math.PI * 2); ctx.fill();
    }
    ctx.fillStyle = 'rgba(255, 247, 230, .06)';
    for (var j = 0; j < h; j += 4) ctx.fillRect(0, j, w, 1);
  }

  var avatarEl = document.getElementById('avatar');
  var slotEl = document.getElementById('slot');
  var shimmerEl = document.getElementById('shimmer');
  var readoutEl = document.getElementById('readout');
  if (!avatarEl || !slotEl || !shimmerEl || !readoutEl) return;
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  drawSeedThumb(avatarEl, 106);

  var CYCLE_MS = 2000;

  function apply(t) {
    // 계산 겹: Elapsed 시간 비율 → 그라디언트 회전각(0~360도)
    var angle = Math.floor((t / CYCLE_MS) * 360);
    slotEl.style.setProperty('--spin', angle + 'deg');

    var prog = t / CYCLE_MS;
    var sweep = -30 + prog * 160;
    shimmerEl.style.transform = 'translateX(' + sweep.toFixed(1) + '%)';

    readoutEl.textContent = 'Angle ' + angle + '°';
  }

  if (reduce) {
    apply(0);
    return;
  }

  var start = null;
  function loop(ts) {
    if (start === null) start = ts;
    var t = (ts - start) % CYCLE_MS;
    apply(t);
    requestAnimationFrame(loop);
  }
  requestAnimationFrame(loop);
})();

import { useEffect, useRef } from "react";
import styles from "./EmbedInstagram.module.scss";

// 사각 카드 임베드 — 이미지 자리는 각도가 도는 그라디언트(계산 겹)로 채우고,
// 그 위를 옅은 띠(shimmer)가 가로질러 로딩 느낌을 더한다. 실키·실서버 요청 없음.
const CYCLE_MS = 2000;

function mulberry32(seed: number) {
  let a = seed >>> 0;
  return function () {
    a |= 0;
    a = (a + 0x6d2b79f5) | 0;
    let t = Math.imul(a ^ (a >>> 15), 1 | a);
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
}

function drawSeedThumb(canvas: HTMLCanvasElement, seed: number) {
  const ctx = canvas.getContext("2d");
  if (!ctx) return;
  const rnd = mulberry32(seed);
  const w = canvas.width;
  const h = canvas.height;
  const hues = [216, 32, 268, 168];
  ctx.fillStyle = "hsl(" + hues[Math.floor(rnd() * hues.length)] + ", 38%, 22%)";
  ctx.fillRect(0, 0, w, h);
  for (let i = 0; i < 6; i++) {
    const cx = rnd() * w;
    const cy = rnd() * h;
    const r = (0.18 + rnd() * 0.3) * Math.min(w, h);
    ctx.fillStyle =
      "hsla(" + hues[Math.floor(rnd() * hues.length)] + ", " + (44 + rnd() * 22).toFixed(1) + "%, " + (38 + rnd() * 26).toFixed(1) + "%, .5)";
    ctx.beginPath();
    ctx.arc(cx, cy, r, 0, Math.PI * 2);
    ctx.fill();
  }
  ctx.fillStyle = "rgba(255, 247, 230, .06)";
  for (let j = 0; j < h; j += 4) ctx.fillRect(0, j, w, 1);
}

export default function EmbedInstagram() {
  const avatarRef = useRef<HTMLCanvasElement>(null);
  const slotRef = useRef<HTMLDivElement>(null);
  const shimmerRef = useRef<HTMLDivElement>(null);
  const readoutRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const avatarEl = avatarRef.current;
    const slotEl = slotRef.current;
    const shimmerEl = shimmerRef.current;
    const readoutEl = readoutRef.current;
    if (!avatarEl || !slotEl || !shimmerEl || !readoutEl) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    drawSeedThumb(avatarEl, 106);

    function apply(t: number) {
      // 계산 겹: 경과 시간 비율 → 그라디언트 회전각(0~360도)
      const angle = Math.floor((t / CYCLE_MS) * 360);
      slotEl!.style.setProperty("--spin", angle + "deg");

      const prog = t / CYCLE_MS;
      const sweep = -30 + prog * 160;
      shimmerEl!.style.transform = "translateX(" + sweep.toFixed(1) + "%)";

      readoutEl!.textContent = "각도 " + angle + "°";
    }

    if (reduce) {
      apply(0);
      return;
    }

    let start: number | null = null;
    let raf = 0;
    function loop(ts: number) {
      if (start === null) start = ts;
      const t = (ts - start) % CYCLE_MS;
      apply(t);
      raf = requestAnimationFrame(loop);
    }
    raf = requestAnimationFrame(loop);
    return () => cancelAnimationFrame(raf);
  }, []);

  return (
    <div className={styles.stage}>
      <div className={styles.card}>
        <div className={styles.topBar}>
          <canvas className={styles.avatar} ref={avatarRef} width={64} height={64} />
          <span className={styles.handle}>channel.a</span>
          <span className={styles.follow}>팔로우</span>
        </div>
        <div className={styles.slot} ref={slotRef}>
          <div className={styles.shimmer} ref={shimmerRef} aria-hidden="true" />
        </div>
        <div className={styles.bottomRow}>
          <svg className={styles.heartIcon} viewBox="0 0 256 256" aria-hidden="true">
            <g fill="currentColor">
              <path
                d="M232 102c0 66-104 122-104 122S24 168 24 102a54 54 0 0 1 54-54c22.59 0 41.94 12.31 50 32c8.06-19.69 27.41-32 50-32a54 54 0 0 1 54 54"
                opacity=".2"
              />
              <path d="M178 40c-20.65 0-38.73 8.88-50 23.89C116.73 48.88 98.65 40 78 40a62.07 62.07 0 0 0-62 62c0 70 103.79 126.66 108.21 129a8 8 0 0 0 7.58 0C136.21 228.66 240 172 240 102a62.07 62.07 0 0 0-62-62m-50 174.8c-18.26-10.64-96-59.11-96-112.8a46.06 46.06 0 0 1 46-46c19.45 0 35.78 10.36 42.6 27a8 8 0 0 0 14.8 0c6.82-16.67 23.15-27 42.6-27a46.06 46.06 0 0 1 46 46c0 53.61-77.76 102.15-96 112.8" />
            </g>
          </svg>
          <span className={styles.likeLabel}>좋아요 128</span>
          <span className={styles.caption}>새 게시물 미리보기</span>
        </div>
      </div>
      <div className={styles.readout} ref={readoutRef}>
        각도 214°
      </div>
    </div>
  );
}