01Gradient Thermometer Input Filled by a Temperature Value

<main class="stage">
<div class="tc is-demo" id="tc">
  <label class="tc__cap" for="tcC">Celsius value</label>
  <div class="tc__body">
    <input class="tc__input" id="tcC" type="number" inputmode="decimal" step="0.5" min="-10" max="40" value="22" aria-label="Entering a Celsius value also calculates Fahrenheit and moves the scale handle" aria-describedby="tcReadout">
    <div class="tc__scale" aria-hidden="true">
      <div class="tc__track"></div>
      <div class="tc__handle" id="tcHandle"></div>
    </div>
  </div>
  <p class="tc__readout" id="tcReadout" role="status" aria-live="polite"></p>
</div>
</main>

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

// 계산 겹(섭씨->화씨, 위치 산출)은 index.html 의 celsiusToFahrenheit()/applyValue() 에 있다. 여기는 무대·레이아웃만.
$duration: $dur-loop;
$easing:   $ease-spring;
$color:    $subject-cream;

@include stage($stage-ink);

.tc {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-2;
  width: min(220px, 84vw);
  background: $subject-blue-deep;
  border-radius: $r-card;
  padding: $sp-4;
  box-shadow: $shadow-raised;
}

.tc__cap {
  margin: 0;
  color: $color;
  font-size: 12px;
  font-weight: 500;
  line-height: 1.2;
}

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

.tc__input {
  width: 68px;
  border: 0;
  border-radius: $r-control;
  padding: $sp-1 $sp-2;
  background: $subject-cream;
  color: $subject-ink;
  font-weight: 700;
  font-size: 15px;
  text-align: center;
}

.tc__input:focus-visible {
  outline: 2px solid $color;
  outline-offset: 2px;
}

.tc__scale {
  position: relative;
  width: 20px;
  height: 92px;
  border-radius: $r-pill;
}

.tc__track {
  position: absolute;
  inset: 0;
  border-radius: $r-pill;
  background: linear-gradient(to top, $subject-blue, $stage-orange);
}

.tc__handle {
  position: absolute;
  top: 0;
  left: 50%;
  width: 14px;
  height: 14px;
  margin-left: -7px;
  border-radius: 50%;
  background: $subject-cream;
  box-shadow: $shadow-press;
  transition: box-shadow $duration $easing;
  will-change: transform;
}

.tc__readout {
  margin: 0;
  color: $color;
  font-size: 12px;
  font-weight: 500;
  line-height: 1.3;
  text-align: center;
}

@media (max-width: 340px) {
  .tc { padding: $sp-3; gap: $sp-1; width: min(200px, 84vw); }
  .tc__cap { font-size: 10px; }
  .tc__body { gap: $sp-1; }
  .tc__input { width: 56px; padding: $sp-1; font-size: 13px; }
  .tc__scale { height: 56px; width: 16px; }
  .tc__handle { width: 12px; height: 12px; margin-left: -6px; }
  .tc__readout { font-size: 10px; }
}

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

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);
}

.tc {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: min(220px, 84vw);
  background: #0a4fe8;
  border-radius: 16px;
  padding: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.tc__cap {
  margin: 0;
  color: #fff7e6;
  font-size: 12px;
  font-weight: 500;
  line-height: 1.2;
}

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

.tc__input {
  width: 68px;
  border: 0;
  border-radius: 12px;
  padding: 4px 8px;
  background: #fff7e6;
  color: #17141a;
  font-weight: 700;
  font-size: 15px;
  text-align: center;
}

.tc__input:focus-visible {
  outline: 2px solid #fff7e6;
  outline-offset: 2px;
}

.tc__scale {
  position: relative;
  width: 20px;
  height: 92px;
  border-radius: 999px;
}

.tc__track {
  position: absolute;
  inset: 0;
  border-radius: 999px;
  background: linear-gradient(to top, #2f6df6, #ff4d1f);
}

.tc__handle {
  position: absolute;
  top: 0;
  left: 50%;
  width: 14px;
  height: 14px;
  margin-left: -7px;
  border-radius: 50%;
  background: #fff7e6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  transition: box-shadow 2s cubic-bezier(0.2, 0.8, 0.2, 1);
  will-change: transform;
}

.tc__readout {
  margin: 0;
  color: #fff7e6;
  font-size: 12px;
  font-weight: 500;
  line-height: 1.3;
  text-align: center;
}

@media (max-width: 340px) {
  .tc {
    padding: 12px;
    gap: 4px;
    width: min(200px, 84vw);
  }
  .tc__cap {
    font-size: 10px;
  }
  .tc__body {
    gap: 4px;
  }
  .tc__input {
    width: 56px;
    padding: 4px;
    font-size: 13px;
  }
  .tc__scale {
    height: 56px;
    width: 16px;
  }
  .tc__handle {
    width: 12px;
    height: 12px;
    margin-left: -6px;
  }
  .tc__readout {
    font-size: 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .tc__handle {
    transition: none;
  }
}

(function () {
  var root = document.getElementById('tc');
  var input = document.getElementById('tcC');
  var handle = document.getElementById('tcHandle');
  var scale = handle.parentElement;
  var readout = document.getElementById('tcReadout');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  var isDemo = true;

  function human() { if (isDemo) { root.classList.remove('is-demo'); isDemo = false; } }

  var MIN_C = -10, MAX_C = 40;
  // 계산 한 겹 — Celsius -> 화씨, 그리고 눈금 위 위치(0~1)
  function celsiusToFahrenheit(c) { return c * 9 / 5 + 32; }
  function clamp01(v) { return v < 0 ? 0 : v > 1 ? 1 : v; }

  var SENT_PREFIX = 'Celsius ', SENT_MID = ' degrees is Fahrenheit ', SENT_SUFFIX = ' degrees.';

  var targetT = 0, renderedT = 0;
  var LERP_RATE = 0.14; // 변형 01: 낮추면 손잡이가 값 변화를 더 천천히 뒤따라간다

  function readValue() {
    var c = parseFloat(input.value);
    return isNaN(c) ? 0 : c;
  }

  function applyValue(c) {
    var f = celsiusToFahrenheit(c);
    targetT = clamp01((c - MIN_C) / (MAX_C - MIN_C));
    readout.textContent = SENT_PREFIX + c.toFixed(1) + SENT_MID + f.toFixed(1) + SENT_SUFFIX;
    if (reduce) { renderedT = targetT; paint(); }
  }

  function paint() {
    var trackH = scale.clientHeight - handle.offsetHeight;
    var y = (1 - renderedT) * trackH;
    handle.style.transform = 'translateY(' + y.toFixed(1) + 'px)';
  }

  input.addEventListener('input', function () { human(); applyValue(readValue()); });
  input.addEventListener('change', function () { human(); applyValue(readValue()); });

  var DEMO_VALUES = [-4, 8, 22, 31, 38, 14];
  var DRIVE_PERIOD_MS = 2000; // 렌더 캐처 창(설정 초=2.0)과 같은 주기 — 시연 전용
  var driveStart = 0, lastIdx = -1;
  function driveTick(now) {
    if (!driveStart) driveStart = now;
    if (isDemo) {
      var frac = ((now - driveStart) % DRIVE_PERIOD_MS) / DRIVE_PERIOD_MS;
      var idx = Math.floor(frac * DEMO_VALUES.length);
      if (idx !== lastIdx) {
        lastIdx = idx;
        input.value = DEMO_VALUES[idx];
        applyValue(DEMO_VALUES[idx]);
      }
    }
    requestAnimationFrame(driveTick);
  }

  function frame() {
    renderedT += (targetT - renderedT) * LERP_RATE;
    paint();
    requestAnimationFrame(frame);
  }

  window.addEventListener('resize', paint);
  applyValue(readValue());

  if (!reduce) {
    requestAnimationFrame(driveTick);
    requestAnimationFrame(frame);
  }
})();

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

export default function GradientThermometer() {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const inputRef = useRef<HTMLInputElement | null>(null);
  const handleRef = useRef<HTMLDivElement | null>(null);
  const readoutRef = useRef<HTMLParagraphElement | null>(null);

  useEffect(() => {
    const root = rootRef.current;
    const input = inputRef.current;
    const handle = handleRef.current;
    const readout = readoutRef.current;
    if (!root || !input || !handle || !readout) return;
    const scale = handle.parentElement as HTMLDivElement;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    let isDemo = true;

    function human() {
      if (isDemo) {
        root!.classList.remove("is-demo");
        isDemo = false;
      }
    }

    const MIN_C = -10;
    const MAX_C = 40;
    function celsiusToFahrenheit(c: number) {
      return (c * 9) / 5 + 32;
    }
    function clamp01(v: number) {
      return v < 0 ? 0 : v > 1 ? 1 : v;
    }

    const SENT_PREFIX = "섭씨 ";
    const SENT_MID = "도는 화씨 ";
    const SENT_SUFFIX = "도입니다";

    let targetT = 0;
    let renderedT = 0;
    const LERP_RATE = 0.14;

    function readValue() {
      const c = parseFloat(input!.value);
      return isNaN(c) ? 0 : c;
    }

    function applyValue(c: number) {
      const f = celsiusToFahrenheit(c);
      targetT = clamp01((c - MIN_C) / (MAX_C - MIN_C));
      readout!.textContent = SENT_PREFIX + c.toFixed(1) + SENT_MID + f.toFixed(1) + SENT_SUFFIX;
      if (reduce) {
        renderedT = targetT;
        paint();
      }
    }

    function paint() {
      const trackH = scale.clientHeight - handle!.offsetHeight;
      const y = (1 - renderedT) * trackH;
      handle!.style.transform = "translateY(" + y.toFixed(1) + "px)";
    }

    function onInput() {
      human();
      applyValue(readValue());
    }
    input.addEventListener("input", onInput);
    input.addEventListener("change", onInput);

    const DEMO_VALUES = [-4, 8, 22, 31, 38, 14];
    const DRIVE_PERIOD_MS = 2000;
    let driveStart = 0;
    let lastIdx = -1;
    let rafDrive = 0;
    function driveTick(now: number) {
      if (!driveStart) driveStart = now;
      if (isDemo) {
        const frac = ((now - driveStart) % DRIVE_PERIOD_MS) / DRIVE_PERIOD_MS;
        const idx = Math.floor(frac * DEMO_VALUES.length);
        if (idx !== lastIdx) {
          lastIdx = idx;
          input!.value = String(DEMO_VALUES[idx]);
          applyValue(DEMO_VALUES[idx]);
        }
      }
      rafDrive = requestAnimationFrame(driveTick);
    }

    let rafFrame = 0;
    function frame() {
      renderedT += (targetT - renderedT) * LERP_RATE;
      paint();
      rafFrame = requestAnimationFrame(frame);
    }

    window.addEventListener("resize", paint);
    applyValue(readValue());

    if (!reduce) {
      rafDrive = requestAnimationFrame(driveTick);
      rafFrame = requestAnimationFrame(frame);
    }

    return () => {
      input.removeEventListener("input", onInput);
      input.removeEventListener("change", onInput);
      window.removeEventListener("resize", paint);
      if (rafDrive) cancelAnimationFrame(rafDrive);
      if (rafFrame) cancelAnimationFrame(rafFrame);
    };
  }, []);

  return (
    <div ref={rootRef} className={`${styles.tc} is-demo`}>
      <label className={styles.cap} htmlFor="tcCReact">
        섭씨 값
      </label>
      <div className={styles.body}>
        <input
          ref={inputRef}
          className={styles.input}
          id="tcCReact"
          type="number"
          inputMode="decimal"
          step={0.5}
          min={-10}
          max={40}
          defaultValue={22}
          aria-label="섭씨 값을 입력하면 화씨로 함께 계산해 눈금 손잡이를 옮깁니다"
          aria-describedby="tcReadoutReact"
        />
        <div className={styles.scale} aria-hidden="true">
          <div className={styles.track} />
          <div ref={handleRef} className={styles.handle} />
        </div>
      </div>
      <p ref={readoutRef} className={styles.readout} id="tcReadoutReact" role="status" aria-live="polite" />
    </div>
  );
}