03Multi-glyph composed typing

<main class="stage">
  <p class="glyph"><span class="glyph__text" id="gtext">Hello Godrich 🎉</span></p>
</main>

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

$duration: $dur-loop;                      // JS 쪽 el.animate() duration:2000 과 맞춘다
$easing: linear;                           // 글자 폭 기준 offset 을 이미 곡선으로 넣어 linear 로 충분하다
$color: $subject-cream;                    // 글자 색

@include stage($stage-orange);

.glyph {
  margin: 0;
  font-weight: 700; font-size: clamp(22px, 6.4vw, 40px); line-height: 1.4; font-family: inherit;
  color: $color;

  &__text {
    display: inline-block;
  }
}

@media (prefers-reduced-motion: reduce) {
  .glyph__text { clip-path: none !important; }
}

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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.glyph {
  margin: 0;
  font-weight: 700;
  font-size: clamp(22px, 6.4vw, 40px);
  line-height: 1.4;
  font-family: inherit;
  color: #fff7e6;
}
.glyph__text {
  display: inline-block;
}

@media (prefers-reduced-motion: reduce) {
  .glyph__text {
    clip-path: none !important;
  }
}

(function () {
  if (matchMedia('(prefers-reduced-motion: reduce)').matches) return;
  var el = document.getElementById('gtext'), s = el.textContent, cv = document.createElement('canvas').getContext('2d');
  cv.font = getComputedStyle(el).font;
  var w = 0, cum = [0];
  for (var i = 0; i < s.length; i++) { w += cv.measureText(s[i]).width; cum.push(w); }
  var kf = cum.map(function (px) { return { clipPath: 'inset(0 ' + (100 - px / w * 70) + '% 0 0)', offset: px / w * .7 }; });
  kf.push({ clipPath: 'inset(0 0% 0 0)', offset: .88 }, { clipPath: 'inset(0 100% 0 0)', offset: 1 });
  el.animate(kf, { duration: 2000, iterations: Infinity });
})();

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

export type MultiGlyphTypingProps = {
  text: string;
  /** el.animate() duration (기본 2000ms) */
  duration?: number;
  color?: string;
};

export default function MultiGlyphTyping({ text, duration = 2000, color = "#fff7e6" }: MultiGlyphTypingProps) {
  const ref = useRef<HTMLSpanElement | null>(null);
  useEffect(() => {
    const el = ref.current;
    if (!el || matchMedia("(prefers-reduced-motion: reduce)").matches) return;
    const cv = document.createElement("canvas").getContext("2d");
    if (!cv) return;
    cv.font = getComputedStyle(el).font;
    let w = 0;
    const cum = [0];
    for (let i = 0; i < text.length; i++) { w += cv.measureText(text[i]).width; cum.push(w); }
    const kf = cum.map((px) => ({ clipPath: "inset(0 " + (100 - (px / w) * 70) + "% 0 0)", offset: (px / w) * 0.7 }));
    kf.push({ clipPath: "inset(0 0% 0 0)", offset: 0.88 }, { clipPath: "inset(0 100% 0 0)", offset: 1 });
    const anim = el.animate(kf, { duration, iterations: Infinity });
    return () => anim.cancel();
  }, [text, duration]);
  const vars = { "--color": color } as CSSProperties;
  return (
    <p className={styles.glyph} style={vars}>
      <span ref={ref} className={styles.text}>{text}</span>
    </p>
  );
}