09ローディングモーフ（ボタン→スピナー→チェック）

<main class="stage">
  <button class="morph is-demo" type="button">
    <span class="morph__label">支払う</span>
    <span class="morph__spin" aria-hidden="true"></span>
    <svg class="morph__check" viewBox="0 0 24 24" aria-hidden="true"><polyline points="5 12.5 10 17.5 19 7.5"/></svg>
  </button>
</main>

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

// 변형은 이 세 줄만 바꾼다
$duration: $dur-loop;
$easing:   $ease-spring;
$color:    $subject-cream;

@include stage($stage-orange);

.morph {
  position: relative;
  display: grid;
  place-items: center;
  width: 200px;
  height: 56px;
  border: 0;
  cursor: pointer;
  padding: 0;
  border-radius: $r-pill;
  background: $color;
  color: $stage-orange;
  font-family: inherit;
  font-size: 18px;
  font-weight: 800;
  overflow: hidden;
}

.morph__label,
.morph__spin,
.morph__check { grid-area: 1 / 1; }

.morph__spin {
  width: 24px;
  height: 24px;
  border: 3px solid rgba($stage-orange, .25);
  border-top-color: $stage-orange;
  border-radius: 50%;
  opacity: 0;
}

.morph__check {
  width: 26px;
  height: 26px;
  fill: none;
  stroke: $stage-orange;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-dasharray: 26;
  stroke-dashoffset: 26;
  opacity: 0;
}

.morph.is-demo { animation: morph-box $duration $easing infinite; }
.morph.is-demo .morph__label { animation: morph-label $duration $easing infinite; }
.morph.is-demo .morph__spin  { animation: morph-spin-in $duration $easing infinite, morph-turn 800ms linear infinite; }
.morph.is-demo .morph__check { animation: morph-draw $duration $easing infinite; }

// 200 → 56 → 200. 마지막이 처음과 같은 폭이라 한 바퀴가 이어진다
@keyframes morph-box {
  0%,  10% { width: 200px; }
  28%, 62% { width: 56px; }
  84%, 100% { width: 200px; }
}

@keyframes morph-label {
  0%,  8%  { opacity: 1; }
  20%, 80% { opacity: 0; }
  92%, 100% { opacity: 1; }
}

@keyframes morph-spin-in {
  0%,  22% { opacity: 0; }
  30%, 56% { opacity: 1; }
  62%, 100% { opacity: 0; }
}

// 360deg 로 끝나 다음 바퀴와 맞물린다
@keyframes morph-turn {
  to { rotate: 360deg; }
}

@keyframes morph-draw {
  0%,  60% { stroke-dashoffset: 26; opacity: 0; }
  64%      { stroke-dashoffset: 26; opacity: 1; }
  76%, 86% { stroke-dashoffset: 0;  opacity: 1; }
  94%, 100% { stroke-dashoffset: 26; opacity: 0; }
}

// 실제 클릭 상태 — 데모 루프가 아니라 사람이 눌렀을 때
.morph.is-busy { width: 56px; }
.morph.is-busy .morph__label { opacity: 0; }
.morph.is-busy .morph__spin { opacity: 1; animation: morph-turn 800ms linear infinite; }
.morph.is-done .morph__check { opacity: 1; stroke-dashoffset: 0; transition: stroke-dashoffset $dur-enter $easing; }
.morph.is-done .morph__label { opacity: 0; }

@media (prefers-reduced-motion: reduce) {
  .morph.is-demo,
  .morph.is-demo .morph__label,
  .morph.is-demo .morph__spin,
  .morph.is-demo .morph__check { animation: none; }
  .morph.is-busy .morph__spin { animation: none; }
}

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);
}

.morph {
  position: relative;
  display: grid;
  place-items: center;
  width: 200px;
  height: 56px;
  border: 0;
  cursor: pointer;
  padding: 0;
  border-radius: 999px;
  background: #fff7e6;
  color: #ff4d1f;
  font-family: inherit;
  font-size: 18px;
  font-weight: 800;
  overflow: hidden;
}

.morph__label,
.morph__spin,
.morph__check {
  grid-area: 1/1;
}

.morph__spin {
  width: 24px;
  height: 24px;
  border: 3px solid rgba(255, 77, 31, 0.25);
  border-top-color: #ff4d1f;
  border-radius: 50%;
  opacity: 0;
}

.morph__check {
  width: 26px;
  height: 26px;
  fill: none;
  stroke: #ff4d1f;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-dasharray: 26;
  stroke-dashoffset: 26;
  opacity: 0;
}

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

.morph.is-demo .morph__label {
  animation: morph-label 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.morph.is-demo .morph__spin {
  animation: morph-spin-in 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite, morph-turn 800ms linear infinite;
}

.morph.is-demo .morph__check {
  animation: morph-draw 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@keyframes morph-box {
  0%, 10% {
    width: 200px;
  }
  28%, 62% {
    width: 56px;
  }
  84%, 100% {
    width: 200px;
  }
}
@keyframes morph-label {
  0%, 8% {
    opacity: 1;
  }
  20%, 80% {
    opacity: 0;
  }
  92%, 100% {
    opacity: 1;
  }
}
@keyframes morph-spin-in {
  0%, 22% {
    opacity: 0;
  }
  30%, 56% {
    opacity: 1;
  }
  62%, 100% {
    opacity: 0;
  }
}
@keyframes morph-turn {
  to {
    rotate: 360deg;
  }
}
@keyframes morph-draw {
  0%, 60% {
    stroke-dashoffset: 26;
    opacity: 0;
  }
  64% {
    stroke-dashoffset: 26;
    opacity: 1;
  }
  76%, 86% {
    stroke-dashoffset: 0;
    opacity: 1;
  }
  94%, 100% {
    stroke-dashoffset: 26;
    opacity: 0;
  }
}
.morph.is-busy {
  width: 56px;
}

.morph.is-busy .morph__label {
  opacity: 0;
}

.morph.is-busy .morph__spin {
  opacity: 1;
  animation: morph-turn 800ms linear infinite;
}

.morph.is-done .morph__check {
  opacity: 1;
  stroke-dashoffset: 0;
  transition: stroke-dashoffset 600ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.morph.is-done .morph__label {
  opacity: 0;
}

@media (prefers-reduced-motion: reduce) {
  .morph.is-demo,
  .morph.is-demo .morph__label,
  .morph.is-demo .morph__spin,
  .morph.is-demo .morph__check {
    animation: none;
  }
  .morph.is-busy .morph__spin {
    animation: none;
  }
}

// 실제 동작: 누르면 aria-busy 로 상태를 알리고 1.2초 뒤 체크로 끝난다. 그동안 두 번 눌리지 않는다.
var morph = document.querySelector('.morph');
morph.addEventListener('click', function () {
  if (morph.classList.contains('is-busy')) { return; }
  morph.classList.remove('is-demo');
  morph.classList.add('is-busy');
  morph.setAttribute('aria-busy', 'true');
  setTimeout(function () {
    morph.classList.remove('is-busy');
    morph.classList.add('is-done');
    morph.removeAttribute('aria-busy');
  }, 1200);
});

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

export type StateMorphButtonProps = {
  label?: string;
  duration?: number;
  easing?: string;
  color?: string;
  onSubmit?: () => Promise<void>;
};

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

export default function StateMorphButton({
  label = "Pay now",
  duration = 2000,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#fff7e6",
  onSubmit,
}: StateMorphButtonProps) {
  const [state, setState] = useState<"idle" | "busy" | "done">("idle");

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

  function run() {
    if (state === "busy") { return; }
    setState("busy");
    const job = onSubmit ? onSubmit() : new Promise<void>((r) => setTimeout(r, 1200));
    job.then(() => setState("done"));
  }

  const cls = state === "busy" ? styles.busy : state === "done" ? styles.done : styles.loop;

  return (
    <button
      type="button"
      className={`${styles.morph} ${cls}`}
      style={vars}
      aria-busy={state === "busy"}
      onClick={run}
    >
      <span className={styles.label}>{label}</span>
      <span className={styles.spin} aria-hidden="true" />
      <svg className={styles.check} viewBox="0 0 24 24" aria-hidden="true">
        <polyline points="5 12.5 10 17.5 19 7.5" />
      </svg>
    </button>
  );
}