08Scroll-progress cursor ring

<main class="stage">
  <div class="pr-box is-demo">
    <div class="pr-content">
      <p>Scroll inside this box and</p>
      <p>the ring beside the cursor</p>
      <p>fills up with the progress</p>
      <p>and turns into a check at the end</p>
    </div>
    <div class="pr-ring" aria-hidden="true">
      <svg viewBox="0 0 36 36">
        <circle class="pr-ring__track" cx="18" cy="18" r="15"/>
        <circle class="pr-ring__fill" cx="18" cy="18" r="15"/>
      </svg>
      <svg class="pr-ring__check" viewBox="0 0 256 256"><g fill="currentColor"><path d="M232 56v144a16 16 0 0 1-16 16H40a16 16 0 0 1-16-16V56a16 16 0 0 1 16-16h176a16 16 0 0 1 16 16" opacity=".2"/><path d="m205.66 85.66l-96 96a8 8 0 0 1-11.32 0l-40-40a8 8 0 0 1 11.32-11.32L104 164.69l90.34-90.35a8 8 0 0 1 11.32 11.32"/></g></svg>
    </div>
  </div>
</main>

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

$duration: $dur-quick;
$easing: $ease-out;
$color: $subject-blue;

@include stage($stage-ink);

.pr-box {
  position: relative;
  width: min(230px, 76vw);
  height: 150px;
  overflow-y: auto;
  border-radius: $r-card;
  background: #1c1822;
  cursor: none;
}

.pr-content {
  padding: $sp-4;
  height: 340px;
  p { margin: 0 0 $sp-6; font-size: 13px; font-weight: 700; color: rgba(255, 255, 255, .55); }
}

.pr-ring {
  position: absolute;
  left: 0;
  top: 0;
  width: 34px;
  height: 34px;
  margin: -17px 0 0 -17px;
  pointer-events: none;
  transform: translate(24px, 112px);
  transition: transform $duration $easing;
}
.pr-ring svg:first-child { transform: rotate(-90deg); }
.pr-ring__track { fill: none; stroke: rgba(255, 255, 255, .18); stroke-width: 3; }
.pr-ring__fill {
  fill: none;
  stroke: $color;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-dasharray: 94.2;
  stroke-dashoffset: var(--dash, 94.2);
}
.pr-ring__check {
  position: absolute;
  inset: 8px;
  color: $subject-mint;
  opacity: 0;
}

.pr-box.is-done .pr-ring__check { opacity: 1; }
.pr-box.is-done .pr-ring svg:first-child { opacity: 0; }

// 데모 강제 루프 — 실제 스크롤 없이도 링이 채워졌다가 체크로 바뀐다
.pr-box.is-demo { overflow: hidden; }
.pr-box.is-demo .pr-ring { animation: pr-move $dur-loop $easing infinite; transition: none; }
.pr-box.is-demo .pr-ring__fill { animation: pr-fill $dur-loop $easing infinite; }
.pr-box.is-demo .pr-ring__check { animation: pr-check $dur-loop $easing infinite; }
@keyframes pr-move {
  0%, 8%    { transform: translate(24px, 112px); }
  50%       { transform: translate(150px, 40px); }
  92%, 100% { transform: translate(24px, 112px); }
}
@keyframes pr-fill {
  0%, 8%    { stroke-dashoffset: 94.2; }
  50%, 62%  { stroke-dashoffset: 0; }
  92%, 100% { stroke-dashoffset: 94.2; }
}
@keyframes pr-check {
  0%, 46%   { opacity: 0; }
  52%, 60%  { opacity: 1; }
  68%, 100% { opacity: 0; }
}

@media (hover: none), (pointer: coarse) {
  .pr-box { cursor: auto; }                             // 터치엔 커서가 없다 — 링은 스크롤 위치에만 반응하는 진행 표시로 남는다
}

@media (prefers-reduced-motion: reduce) {
  .pr-ring, .pr-ring__fill, .pr-ring__check { animation: none !important; transition: none !important; }
}

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);
}

.pr-box {
  position: relative;
  width: min(230px, 76vw);
  height: 150px;
  overflow-y: auto;
  border-radius: 16px;
  background: #1c1822;
  cursor: none;
}

.pr-content {
  padding: 16px;
  height: 340px;
}
.pr-content p {
  margin: 0 0 24px;
  font-size: 13px;
  font-weight: 700;
  color: rgba(255, 255, 255, 0.55);
}

.pr-ring {
  position: absolute;
  left: 0;
  top: 0;
  width: 34px;
  height: 34px;
  margin: -17px 0 0 -17px;
  pointer-events: none;
  transform: translate(24px, 112px);
  transition: transform 220ms ease-out;
}

.pr-ring svg:first-child {
  transform: rotate(-90deg);
}

.pr-ring__track {
  fill: none;
  stroke: rgba(255, 255, 255, 0.18);
  stroke-width: 3;
}

.pr-ring__fill {
  fill: none;
  stroke: #2f6df6;
  stroke-width: 3;
  stroke-linecap: round;
  stroke-dasharray: 94.2;
  stroke-dashoffset: var(--dash, 94.2);
}

.pr-ring__check {
  position: absolute;
  inset: 8px;
  color: #4cd4a6;
  opacity: 0;
}

.pr-box.is-done .pr-ring__check {
  opacity: 1;
}

.pr-box.is-done .pr-ring svg:first-child {
  opacity: 0;
}

.pr-box.is-demo {
  overflow: hidden;
}

.pr-box.is-demo .pr-ring {
  animation: pr-move 2s ease-out infinite;
  transition: none;
}

.pr-box.is-demo .pr-ring__fill {
  animation: pr-fill 2s ease-out infinite;
}

.pr-box.is-demo .pr-ring__check {
  animation: pr-check 2s ease-out infinite;
}

@keyframes pr-move {
  0%, 8% {
    transform: translate(24px, 112px);
  }
  50% {
    transform: translate(150px, 40px);
  }
  92%, 100% {
    transform: translate(24px, 112px);
  }
}
@keyframes pr-fill {
  0%, 8% {
    stroke-dashoffset: 94.2;
  }
  50%, 62% {
    stroke-dashoffset: 0;
  }
  92%, 100% {
    stroke-dashoffset: 94.2;
  }
}
@keyframes pr-check {
  0%, 46% {
    opacity: 0;
  }
  52%, 60% {
    opacity: 1;
  }
  68%, 100% {
    opacity: 0;
  }
}
@media (hover: none), (pointer: coarse) {
  .pr-box {
    cursor: auto;
  }
}
@media (prefers-reduced-motion: reduce) {
  .pr-ring, .pr-ring__fill, .pr-ring__check {
    animation: none !important;
    transition: none !important;
  }
}

(function () {
  var box = document.querySelector('.pr-box');
  var ring = box.querySelector('.pr-ring');
  var CIRC = 2 * Math.PI * 15;
  // 실제 사용자: 포인터를 따라가고, 스크롤 진행률만큼 링 테두리가 채워진다
  box.addEventListener('pointermove', function (e) {
    if (box.classList.contains('is-demo')) return;
    var r = box.getBoundingClientRect();
    ring.style.transform = 'translate(' + (e.clientX - r.left) + 'px,' + (e.clientY - r.top) + 'px)';
  });
  box.addEventListener('scroll', function () {
    if (box.classList.contains('is-demo')) return;
    var max = box.scrollHeight - box.clientHeight;
    var pct = max > 0 ? box.scrollTop / max : 0;
    ring.style.setProperty('--dash', (CIRC * (1 - pct)).toFixed(1));
    box.classList.toggle('is-done', pct > 0.98);
  });
})();

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

export type CursorScrollProgressRingProps = {
  duration?: number;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
const CIRC = 2 * Math.PI * 15;

/** pointermove 로 커서를 따라가고, 내부 스크롤 비율만큼 stroke-dashoffset 을 채운다 */
export default function CursorScrollProgressRing({
  duration = 220,
  easing = "ease-out",
  color = "#2f6df6",
}: CursorScrollProgressRingProps) {
  const ringRef = useRef<HTMLDivElement>(null);
  const [done, setDone] = useState(false);
  const [dash, setDash] = useState(CIRC);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  const move = (e: PointerEvent<HTMLDivElement>) => {
    const ring = ringRef.current;
    if (!ring) return;
    const r = e.currentTarget.getBoundingClientRect();
    ring.style.transform = `translate(${e.clientX - r.left}px,${e.clientY - r.top}px)`;
  };
  const scroll = (e: { currentTarget: HTMLDivElement }) => {
    const box = e.currentTarget;
    const max = box.scrollHeight - box.clientHeight;
    const pct = max > 0 ? box.scrollTop / max : 0;
    setDash(CIRC * (1 - pct));
    setDone(pct > 0.98);
  };

  return (
    <div className={`${styles.box} ${done ? styles.isDone : ""}`} style={vars} onPointerMove={move} onScroll={scroll}>
      <div className={styles.content}>
        <p>이 안에서 스크롤하면</p>
        <p>커서 옆 링이</p>
        <p>진행률만큼 채워진다</p>
        <p>끝까지 가면 체크로 바뀐다</p>
      </div>
      <div ref={ringRef} className={styles.ring} aria-hidden="true">
        <svg viewBox="0 0 36 36">
          <circle className={styles.track} cx="18" cy="18" r="15" />
          <circle className={styles.fill} cx="18" cy="18" r="15" style={{ strokeDashoffset: dash }} />
        </svg>
        <svg className={styles.check} viewBox="0 0 256 256"><g fill="currentColor"><path d="M232 56v144a16 16 0 0 1-16 16H40a16 16 0 0 1-16-16V56a16 16 0 0 1 16-16h176a16 16 0 0 1 16 16" opacity=".2" /><path d="m205.66 85.66l-96 96a8 8 0 0 1-11.32 0l-40-40a8 8 0 0 1 11.32-11.32L104 164.69l90.34-90.35a8 8 0 0 1 11.32 11.32" /></g></svg>
      </div>
    </div>
  );
}