02Material slider — a color picker that composes a preview color from three handle positions

<main class="stage">
<section class="panel">
  <div class="preview" id="preview">
    <span class="previewLabel">Preview</span>
  </div>
  <div class="sliders">
    <div class="row">
      <span class="rowLabel">Hue</span>
      <div class="track">
        <div class="fill fillHue" id="fillH"></div>
        <div class="thumb" id="thumbH" role="slider" aria-label="Hue" aria-valuemin="0" aria-valuemax="360" aria-valuenow="0"></div>
      </div>
    </div>
    <div class="row">
      <span class="rowLabel">Saturation</span>
      <div class="track">
        <div class="fill fillSat" id="fillS"></div>
        <div class="thumb" id="thumbS" role="slider" aria-label="Saturation" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0"></div>
      </div>
    </div>
    <div class="row">
      <span class="rowLabel">Lightness</span>
      <div class="track">
        <div class="fill fillLight" id="fillL"></div>
        <div class="thumb" id="thumbL" role="slider" aria-label="Lightness" aria-valuemin="0" aria-valuemax="100" aria-valuenow="0"></div>
      </div>
    </div>
  </div>
</section>
</main>

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

@include stage($stage-paper);

.panel {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: $sp-4;
  width: 100%;
  max-width: 220px;
}

.preview {
  height: 56px;
  border-radius: $r-card;
  display: flex;
  align-items: flex-end;
  padding: $sp-2;
  box-shadow: $shadow-raised;
  color: $subject-cream;

  &.is-ink {
    color: $subject-ink;
  }
}

.previewLabel {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
}

.sliders {
  display: flex;
  flex-direction: column;
  gap: $sp-2;
}

.row {
  display: flex;
  align-items: center;
  gap: $sp-2;
}

.rowLabel {
  flex: 0 0 auto;
  width: 30px;
  color: $subject-ink;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
}

.track {
  position: relative;
  flex: 1 1 auto;
  height: 6px;
  border-radius: $r-pill;
  background: rgba($subject-ink, .1);
}

.fill {
  position: absolute;
  inset: 0;
  border-radius: $r-pill;
  transform-origin: left center;
  transform: scaleX(0);
}

.fillHue { background: $subject-blue; }
.fillSat { background: $subject-blue; }
.fillLight { background: $subject-blue; }

.thumb {
  position: absolute;
  top: 50%;
  left: 0;
  width: 16px;
  height: 16px;
  border-radius: $r-pill;
  background: $stage-paper;
  border: 2px solid $subject-blue;
  box-shadow: $shadow-press;
}

@media (max-width: 340px) {
  .panel { max-width: 168px; }
  .preview { height: 44px; }
  .rowLabel { width: 24px; font-size: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  .thumb { transition: none; }
}

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

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

.panel {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 16px;
  width: 100%;
  max-width: 220px;
}

.preview {
  height: 56px;
  border-radius: 16px;
  display: flex;
  align-items: flex-end;
  padding: 8px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  color: #fff7e6;
}
.preview.is-ink {
  color: #17141a;
}

.previewLabel {
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
}

.sliders {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.row {
  display: flex;
  align-items: center;
  gap: 8px;
}

.rowLabel {
  flex: 0 0 auto;
  width: 30px;
  color: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 500;
  font-size: 11px;
  line-height: 1.3;
}

.track {
  position: relative;
  flex: 1 1 auto;
  height: 6px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.1);
}

.fill {
  position: absolute;
  inset: 0;
  border-radius: 999px;
  transform-origin: left center;
  transform: scaleX(0);
}

.fillHue {
  background: #2f6df6;
}

.fillSat {
  background: #2f6df6;
}

.fillLight {
  background: #2f6df6;
}

.thumb {
  position: absolute;
  top: 50%;
  left: 0;
  width: 16px;
  height: 16px;
  border-radius: 999px;
  background: #ffffff;
  border: 2px solid #2f6df6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

@media (max-width: 340px) {
  .panel {
    max-width: 168px;
  }
  .preview {
    height: 44px;
  }
  .rowLabel {
    width: 24px;
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .thumb {
    transition: none;
  }
}

// Material 슬라이더(02) — Hue·Saturation·Lightness 세 손잡이의 트랙 위치 비율을 각각 다시 구하고,
// 세 값을 합쳐 Preview 색을 매 프레임 다시 계산한다. 실키·실서버 요청 없음.
(function () {
  var previewEl = document.getElementById('preview');
  var thumbH = document.getElementById('thumbH');
  var thumbS = document.getElementById('thumbS');
  var thumbL = document.getElementById('thumbL');
  var fillH = document.getElementById('fillH');
  var fillS = document.getElementById('fillS');
  var fillL = document.getElementById('fillL');
  if (!previewEl || !thumbH || !thumbS || !thumbL || !fillH || !fillS || !fillL) return;
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var CYCLE_MS = 2000;
  var TRACK_W = 156;

  function hslToRgb(h, s, l) {
    s /= 100; l /= 100;
    var k = function (n) { return (n + h / 30) % 12; };
    var a = s * Math.min(l, 1 - l);
    var f = function (n) { return l - a * Math.max(-1, Math.min(k(n) - 3, Math.min(9 - k(n), 1))); };
    return [Math.round(f(0) * 255), Math.round(f(8) * 255), Math.round(f(4) * 255)];
  }

  function valuesAt(t) {
    var p = t / CYCLE_MS;
    var h, s, l;
    if (p < 1 / 3) {
      var local = p / (1 / 3);
      h = local * 360; s = 60; l = 50;
    } else if (p < 2 / 3) {
      var local2 = (p - 1 / 3) / (1 / 3);
      h = 360; s = 20 + local2 * 70; l = 50;
    } else {
      var local3 = (p - 2 / 3) / (1 / 3);
      h = 360; s = 90; l = 20 + local3 * 60;
    }
    return { h: h % 360, s: s, l: l };
  }

  function setThumb(thumbEl, fillEl, ratio) {
    var x = ratio * TRACK_W;
    thumbEl.style.transform = 'translate(calc(-50% + ' + x.toFixed(2) + 'px), -50%)';
    fillEl.style.transform = 'scaleX(' + ratio.toFixed(4) + ')';
  }

  function apply(t) {
    var v = valuesAt(t);
    setThumb(thumbH, fillH, v.h / 360);
    setThumb(thumbS, fillS, v.s / 100);
    setThumb(thumbL, fillL, v.l / 100);

    var rgb = hslToRgb(v.h, v.s, v.l);
    var brightness = (rgb[0] * 299 + rgb[1] * 587 + rgb[2] * 114) / 1000;
    previewEl.style.background = 'hsl(' + v.h.toFixed(1) + 'deg ' + v.s.toFixed(1) + '% ' + v.l.toFixed(1) + '%)';
    previewEl.classList.toggle('is-ink', brightness > 150);

    thumbH.setAttribute('aria-valuenow', Math.round(v.h));
    thumbS.setAttribute('aria-valuenow', Math.round(v.s));
    thumbL.setAttribute('aria-valuenow', Math.round(v.l));
  }

  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 "./ColorPickerMaterialSlider.module.scss";

// Material 슬라이더 — 색조·채도·명도 세 손잡이의 트랙 위치 비율을 각각 다시 구하고
// 세 값을 합쳐 미리보기 색을 매 프레임 다시 계산한다. 실키·실서버 요청 없음.
const CYCLE_MS = 2000;
const TRACK_W = 156;

function hslToRgb(h: number, s: number, l: number): [number, number, number] {
  s /= 100;
  l /= 100;
  const k = (n: number) => (n + h / 30) % 12;
  const a = s * Math.min(l, 1 - l);
  const f = (n: number) => l - a * Math.max(-1, Math.min(k(n) - 3, Math.min(9 - k(n), 1)));
  return [Math.round(f(0) * 255), Math.round(f(8) * 255), Math.round(f(4) * 255)];
}

function valuesAt(t: number) {
  const p = t / CYCLE_MS;
  let h: number, s: number, l: number;
  if (p < 1 / 3) {
    const local = p / (1 / 3);
    h = local * 360; s = 60; l = 50;
  } else if (p < 2 / 3) {
    const local2 = (p - 1 / 3) / (1 / 3);
    h = 360; s = 20 + local2 * 70; l = 50;
  } else {
    const local3 = (p - 2 / 3) / (1 / 3);
    h = 360; s = 90; l = 20 + local3 * 60;
  }
  return { h: h % 360, s, l };
}

export default function ColorPickerMaterialSlider() {
  const previewRef = useRef<HTMLDivElement>(null);
  const thumbHRef = useRef<HTMLDivElement>(null);
  const thumbSRef = useRef<HTMLDivElement>(null);
  const thumbLRef = useRef<HTMLDivElement>(null);
  const fillHRef = useRef<HTMLDivElement>(null);
  const fillSRef = useRef<HTMLDivElement>(null);
  const fillLRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const preview = previewRef.current;
    const thumbH = thumbHRef.current;
    const thumbS = thumbSRef.current;
    const thumbL = thumbLRef.current;
    const fillH = fillHRef.current;
    const fillS = fillSRef.current;
    const fillL = fillLRef.current;
    if (!preview || !thumbH || !thumbS || !thumbL || !fillH || !fillS || !fillL) return;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    function setThumb(thumbEl: HTMLDivElement, fillEl: HTMLDivElement, ratio: number) {
      const x = ratio * TRACK_W;
      thumbEl.style.transform = `translate(calc(-50% + ${x.toFixed(2)}px), -50%)`;
      fillEl.style.transform = `scaleX(${ratio.toFixed(4)})`;
    }

    function apply(t: number) {
      const v = valuesAt(t);
      setThumb(thumbH!, fillH!, v.h / 360);
      setThumb(thumbS!, fillS!, v.s / 100);
      setThumb(thumbL!, fillL!, v.l / 100);

      const rgb = hslToRgb(v.h, v.s, v.l);
      const brightness = (rgb[0] * 299 + rgb[1] * 587 + rgb[2] * 114) / 1000;
      preview!.style.background = `hsl(${v.h.toFixed(1)}deg ${v.s.toFixed(1)}% ${v.l.toFixed(1)}%)`;
      preview!.classList.toggle(styles.isInk, brightness > 150);

      thumbH!.setAttribute("aria-valuenow", String(Math.round(v.h)));
      thumbS!.setAttribute("aria-valuenow", String(Math.round(v.s)));
      thumbL!.setAttribute("aria-valuenow", String(Math.round(v.l)));
    }

    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}>
      <section className={styles.panel}>
        <div className={styles.preview} ref={previewRef}>
          <span className={styles.previewLabel}>미리보기</span>
        </div>
        <div className={styles.sliders}>
          <div className={styles.row}>
            <span className={styles.rowLabel}>색상</span>
            <div className={styles.track}>
              <div className={`${styles.fill} ${styles.fillHue}`} ref={fillHRef} />
              <div className={styles.thumb} ref={thumbHRef} role="slider" aria-label="색상" aria-valuemin={0} aria-valuemax={360} aria-valuenow={0} />
            </div>
          </div>
          <div className={styles.row}>
            <span className={styles.rowLabel}>채도</span>
            <div className={styles.track}>
              <div className={`${styles.fill} ${styles.fillSat}`} ref={fillSRef} />
              <div className={styles.thumb} ref={thumbSRef} role="slider" aria-label="채도" aria-valuemin={0} aria-valuemax={100} aria-valuenow={0} />
            </div>
          </div>
          <div className={styles.row}>
            <span className={styles.rowLabel}>명도</span>
            <div className={styles.track}>
              <div className={`${styles.fill} ${styles.fillLight}`} ref={fillLRef} />
              <div className={styles.thumb} ref={thumbLRef} role="slider" aria-label="명도" aria-valuemin={0} aria-valuemax={100} aria-valuenow={0} />
            </div>
          </div>
        </div>
      </section>
    </div>
  );
}