04明るさ・コントラスト・彩度のスライダー

<main class="stage">
<div class="ad is-demo" id="ad">
  <div class="ad__frame">
    <canvas class="ad__view" id="view" width="320" height="200" role="img" aria-label="サンプル写真"></canvas>
    <span class="ad__ghost" aria-hidden="true"></span>
    <span class="ad__orig" aria-hidden="true"></span>
    <span class="ad__tag">
      <span class="ad__real" id="tag">補正後</span>
      <span class="ad__tagDemo ad__tagDemo--edit" aria-hidden="true">補正後</span>
      <span class="ad__tagDemo ad__tagDemo--orig" aria-hidden="true">元画像</span>
    </span>
  </div>
  <div class="ad__ctl">
    <div class="ad__s">
      <span class="ad__lab" id="labB">明るさ</span>
      <div class="ad__track" data-k="b" role="slider" tabindex="0" aria-labelledby="labB" aria-valuemin="0.5" aria-valuemax="1.5" aria-valuenow="1"><span class="ad__thumb" id="thB"></span></div>
    </div>
    <div class="ad__s">
      <span class="ad__lab" id="labC">コントラスト</span>
      <div class="ad__track" data-k="c" role="slider" tabindex="0" aria-labelledby="labC" aria-valuemin="0.5" aria-valuemax="1.5" aria-valuenow="1"><span class="ad__thumb" id="thC"></span></div>
    </div>
    <div class="ad__s">
      <span class="ad__lab" id="labS">彩度</span>
      <div class="ad__track" data-k="s" role="slider" tabindex="0" aria-labelledby="labS" aria-valuemin="0.5" aria-valuemax="1.5" aria-valuenow="1"><span class="ad__thumb" id="thS"></span></div>
    </div>
  </div>
  <div class="ad__foot">
    <button type="button" class="ad__btn" id="resetBtn">リセット</button>
    <button type="button" class="ad__btn ad__btn--ab" id="abBtn" aria-pressed="false"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" class="ad__ico" aria-hidden="true"><g fill="currentColor"><path d="M80 136a24 24 0 1 1-24-24a24 24 0 0 1 24 24m48-72a24 24 0 1 0 24 24a24 24 0 0 0-24-24m72 80a24 24 0 1 0 24 24a24 24 0 0 0-24-24" opacity=".2"/><path d="M64 105V40a8 8 0 0 0-16 0v65a32 32 0 0 0 0 62v49a8 8 0 0 0 16 0v-49a32 32 0 0 0 0-62m-8 47a16 16 0 1 1 16-16a16 16 0 0 1-16 16m80-95V40a8 8 0 0 0-16 0v17a32 32 0 0 0 0 62v97a8 8 0 0 0 16 0v-97a32 32 0 0 0 0-62m-8 47a16 16 0 1 1 16-16a16 16 0 0 1-16 16m104 64a32.06 32.06 0 0 0-24-31V40a8 8 0 0 0-16 0v97a32 32 0 0 0 0 62v17a8 8 0 0 0 16 0v-17a32.06 32.06 0 0 0 24-31m-32 16a16 16 0 1 1 16-16a16 16 0 0 1-16 16"/></g></svg><span>比較</span></button>
    <span class="ad__codes">
      <code class="ad__realCode" id="code">brightness(1.00) contrast(1.00) saturate(1.00)</code>
      <code class="ad__demoCode ad__demoCode--a" aria-hidden="true">brightness(1.00) contrast(1.00) saturate(1.00)</code>
      <code class="ad__demoCode ad__demoCode--b" aria-hidden="true">brightness(1.18) contrast(1.22) saturate(1.30)</code>
    </span>
  </div>
</div>
</main>

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

// 밝기 대비 채도 슬라이더 — 값 셋이 filter 문자열 하나로 합쳐지고, 비교 버튼이 원본과 번갈아 보여준다.
// 격자 미리보기(.is-demo)는 유령 판 두 장을 겹쳐 쓴다. 아래 판은 filter 를 부드럽게 보간하고,
// 위의 원본 판은 steps(1, end) 로 한 프레임에 덮는다 — 교차 페이드로 하면 두 장이 반투명하게 겹친다.

$duration: $dur-loop;
$easing: $ease-out;
$color: $subject-ink;

@include stage($stage-paper);

.ad { display: flex; flex-direction: column; align-items: center; gap: $sp-2; width: 100%; }
.ad__frame {
  position: relative; height: clamp(76px, 38vh, 132px); aspect-ratio: 16 / 10; max-width: 100%;
  border-radius: $r-sm; overflow: hidden; box-shadow: $shadow-raised;
}
.ad__view { display: block; width: 100%; height: 100%; }
.ad__ghost, .ad__orig {
  display: none; position: absolute; inset: 0;
  background-image: var(--photo); background-size: cover;
}
.ad__tag {
  position: absolute; left: $sp-1; top: $sp-1; padding: 0 $sp-1;
  border-radius: $r-xs; background: rgba(23, 20, 26, .72); color: $subject-cream;
  // 세로 여백은 4px 격자에 안 맞는 2px 이었다 — 0 으로 내리고 행간으로 높이를 만든다
  font-weight: 800; font-size: clamp(8px, 2.1vw, 10px); line-height: 2;
}
.ad__tagDemo { display: none; position: absolute; left: $sp-1; top: 0; }

.ad__ctl { display: flex; justify-content: center; gap: $sp-2; }
.ad__s { display: grid; justify-items: center; gap: $sp-1; width: 88px; }
.ad__lab { font-weight: 800; font-size: clamp(8px, 2.1vw, 10px); color: $color; }
.ad__track {
  position: relative; width: 100%; height: 6px; cursor: pointer;
  border-radius: $r-pill; background: rgba(23, 20, 26, .18);
}
.ad__track:focus-visible { outline: 3px solid $subject-blue; outline-offset: 4px; }
.ad__thumb {
  position: absolute; top: 50%; left: 50%; width: 13px; height: 13px;
  border-radius: 50%; background: $subject-blue; box-shadow: $shadow-press;
  transform: translate(-50%, -50%);
}

.ad__foot { display: flex; align-items: center; gap: $sp-2; flex-wrap: wrap; justify-content: center; }
.ad__btn {
  display: inline-flex; align-items: center; gap: $sp-1; cursor: pointer;
  border: 1px solid rgba(23, 20, 26, .24); background: $stage-paper; color: $color;
  border-radius: $r-pill; font-family: inherit; font-weight: 700; line-height: 1.3;
  font-size: clamp(8px, 2.2vw, 10px); padding: $sp-1 $sp-2;
}
.ad__btn--ab { background: $subject-blue; border-color: $subject-blue; color: $stage-paper; }
.ad__btn:focus-visible { outline: 3px solid $subject-blue; outline-offset: 2px; }
.ad__ico { width: 12px; height: 12px; flex: 0 0 auto; }
.ad__codes {
  position: relative; display: inline-block; min-width: 200px; height: 14px;
  font-family: ui-monospace, "Consolas", monospace; font-size: clamp(8px, 2.1vw, 10px);
  color: rgba(23, 20, 26, .7);
}
.ad__demoCode { display: none; position: absolute; left: 0; top: 0; white-space: nowrap; }

// ── 미리보기 루프: 슬라이더 셋이 8~12% 에 올라가고, 47~66% 에 원본이 한 프레임 덮었다 물러나고,
//    82~86% 에 처음 값으로 내려온다. 24장 표본의 마지막 장이 2초의 95.8% 지점이라 복귀는 그 앞에 끝낸다
.ad.is-demo .ad__view { visibility: hidden; }
.ad.is-demo .ad__ghost {
  display: block;
  animation-name: adTone; animation-duration: $duration;
  animation-timing-function: $easing; animation-iteration-count: infinite;
}
@keyframes adTone {
  0%, 8% { filter: brightness(1) contrast(1) saturate(1); }
  12%, 82% { filter: brightness(1.18) contrast(1.22) saturate(1.3); }
  86%, 100% { filter: brightness(1) contrast(1) saturate(1); }
}
.ad.is-demo .ad__orig {
  display: block;
  animation-name: adCompare; animation-duration: $duration;
  animation-timing-function: steps(1, end); animation-iteration-count: infinite;
}
@keyframes adCompare {
  0%, 46% { opacity: 0; }
  47%, 66% { opacity: 1; }
  67%, 100% { opacity: 0; }
}
.ad.is-demo .ad__real { color: transparent; }
.ad.is-demo .ad__tagDemo {
  display: block;
  animation-duration: $duration;
  animation-timing-function: steps(1, end); animation-iteration-count: infinite;
}
.ad.is-demo .ad__tagDemo--edit { animation-name: adTagEdit; }
.ad.is-demo .ad__tagDemo--orig { animation-name: adTagOrig; }
@keyframes adTagEdit { 0%, 46% { opacity: 1; } 47%, 66% { opacity: 0; } 67%, 100% { opacity: 1; } }
@keyframes adTagOrig { 0%, 46% { opacity: 0; } 47%, 66% { opacity: 1; } 67%, 100% { opacity: 0; } }

.ad.is-demo .ad__thumb {
  animation-duration: $duration;
  animation-timing-function: $easing; animation-iteration-count: infinite;
}
.ad.is-demo #thB { animation-name: adThumbB; }
.ad.is-demo #thC { animation-name: adThumbC; }
.ad.is-demo #thS { animation-name: adThumbS; }
@keyframes adThumbB {
  0%, 8% { transform: translate(-50%, -50%); }
  12%, 82% { transform: translate(-50%, -50%) translateX(16px); }
  86%, 100% { transform: translate(-50%, -50%); }
}
@keyframes adThumbC {
  0%, 8% { transform: translate(-50%, -50%); }
  12%, 82% { transform: translate(-50%, -50%) translateX(19px); }
  86%, 100% { transform: translate(-50%, -50%); }
}
@keyframes adThumbS {
  0%, 8% { transform: translate(-50%, -50%); }
  12%, 82% { transform: translate(-50%, -50%) translateX(26px); }
  86%, 100% { transform: translate(-50%, -50%); }
}
// 비교 버튼은 자기 중심에서 눌린다 — 원점을 모서리에 두면 눌리는 게 아니라 옆으로 밀려 보인다
.ad.is-demo .ad__btn--ab {
  animation-name: adPress; animation-duration: $duration;
  animation-timing-function: $ease-pop; animation-iteration-count: infinite;
}
@keyframes adPress {
  0%, 42% { transform: scale(1); }
  47% { transform: scale(0.88); }
  54%, 62% { transform: scale(1); }
  67% { transform: scale(0.88); }
  74%, 100% { transform: scale(1); }
}

// 값 글자는 보간할 수 없으니 두 칸을 steps(1, end) 로 갈아 끼우고, 슬라이더가 옮겨 가는 구간을
// 한 프레임 안(8~12%)으로 끊는다 — 그래야 어느 장면을 잘라도 글자와 사진이 같은 값을 말한다
.ad.is-demo .ad__realCode { color: transparent; }
.ad.is-demo .ad__demoCode {
  display: block;
  animation-duration: $duration;
  animation-timing-function: steps(1, end); animation-iteration-count: infinite;
}
.ad.is-demo .ad__demoCode--a { animation-name: adCodeA; }
.ad.is-demo .ad__demoCode--b { animation-name: adCodeB; }
@keyframes adCodeA { 0%, 9% { opacity: 1; } 10%, 83% { opacity: 0; } 84%, 100% { opacity: 1; } }
@keyframes adCodeB { 0%, 9% { opacity: 0; } 10%, 83% { opacity: 1; } 84%, 100% { opacity: 0; } }

@media (max-width: 340px) {
  .ad { gap: $sp-1; }
  .ad__ctl { gap: $sp-1; }
  .ad__s { width: 88px; }
}

@media (prefers-reduced-motion: reduce) {
  .ad.is-demo .ad__ghost,
  .ad.is-demo .ad__orig,
  .ad.is-demo .ad__tagDemo,
  .ad.is-demo .ad__thumb,
  .ad.is-demo .ad__btn--ab,
  .ad.is-demo .ad__demoCode { animation: none !important; }
  // 움직임 없이 보정을 올린 상태로 세운다
  .ad.is-demo .ad__ghost { filter: brightness(1.18) contrast(1.22) saturate(1.3) !important; }
  .ad.is-demo .ad__orig { opacity: 0 !important; }
  .ad.is-demo .ad__tagDemo--edit { opacity: 1 !important; }
  .ad.is-demo .ad__tagDemo--orig { opacity: 0 !important; }
  .ad.is-demo #thB { transform: translate(-50%, -50%) translateX(16px) !important; }
  .ad.is-demo #thC { transform: translate(-50%, -50%) translateX(19px) !important; }
  .ad.is-demo #thS { transform: translate(-50%, -50%) translateX(26px) !important; }
  .ad.is-demo .ad__demoCode--a { opacity: 0 !important; }
  .ad.is-demo .ad__demoCode--b { opacity: 1 !important; }
}

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);
}

.ad {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  width: 100%;
}

.ad__frame {
  position: relative;
  height: clamp(76px, 38vh, 132px);
  aspect-ratio: 16/10;
  max-width: 100%;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
}

.ad__view {
  display: block;
  width: 100%;
  height: 100%;
}

.ad__ghost, .ad__orig {
  display: none;
  position: absolute;
  inset: 0;
  background-image: var(--photo);
  background-size: cover;
}

.ad__tag {
  position: absolute;
  left: 4px;
  top: 4px;
  padding: 0 4px;
  border-radius: 4px;
  background: rgba(23, 20, 26, 0.72);
  color: #fff7e6;
  font-weight: 800;
  font-size: clamp(8px, 2.1vw, 10px);
  line-height: 2;
}

.ad__tagDemo {
  display: none;
  position: absolute;
  left: 4px;
  top: 0;
}

.ad__ctl {
  display: flex;
  justify-content: center;
  gap: 8px;
}

.ad__s {
  display: grid;
  justify-items: center;
  gap: 4px;
  width: 88px;
}

.ad__lab {
  font-weight: 800;
  font-size: clamp(8px, 2.1vw, 10px);
  color: #17141a;
}

.ad__track {
  position: relative;
  width: 100%;
  height: 6px;
  cursor: pointer;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.18);
}

.ad__track:focus-visible {
  outline: 3px solid #2f6df6;
  outline-offset: 4px;
}

.ad__thumb {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 13px;
  height: 13px;
  border-radius: 50%;
  background: #2f6df6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  transform: translate(-50%, -50%);
}

.ad__foot {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}

.ad__btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  border: 1px solid rgba(23, 20, 26, 0.24);
  background: #ffffff;
  color: #17141a;
  border-radius: 999px;
  font-family: inherit;
  font-weight: 700;
  line-height: 1.3;
  font-size: clamp(8px, 2.2vw, 10px);
  padding: 4px 8px;
}

.ad__btn--ab {
  background: #2f6df6;
  border-color: #2f6df6;
  color: #ffffff;
}

.ad__btn:focus-visible {
  outline: 3px solid #2f6df6;
  outline-offset: 2px;
}

.ad__ico {
  width: 12px;
  height: 12px;
  flex: 0 0 auto;
}

.ad__codes {
  position: relative;
  display: inline-block;
  min-width: 200px;
  height: 14px;
  font-family: ui-monospace, "Consolas", monospace;
  font-size: clamp(8px, 2.1vw, 10px);
  color: rgba(23, 20, 26, 0.7);
}

.ad__demoCode {
  display: none;
  position: absolute;
  left: 0;
  top: 0;
  white-space: nowrap;
}

.ad.is-demo .ad__view {
  visibility: hidden;
}

.ad.is-demo .ad__ghost {
  display: block;
  animation-name: adTone;
  animation-duration: 2s;
  animation-timing-function: ease-out;
  animation-iteration-count: infinite;
}

@keyframes adTone {
  0%, 8% {
    filter: brightness(1) contrast(1) saturate(1);
  }
  12%, 82% {
    filter: brightness(1.18) contrast(1.22) saturate(1.3);
  }
  86%, 100% {
    filter: brightness(1) contrast(1) saturate(1);
  }
}
.ad.is-demo .ad__orig {
  display: block;
  animation-name: adCompare;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes adCompare {
  0%, 46% {
    opacity: 0;
  }
  47%, 66% {
    opacity: 1;
  }
  67%, 100% {
    opacity: 0;
  }
}
.ad.is-demo .ad__real {
  color: transparent;
}

.ad.is-demo .ad__tagDemo {
  display: block;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.ad.is-demo .ad__tagDemo--edit {
  animation-name: adTagEdit;
}

.ad.is-demo .ad__tagDemo--orig {
  animation-name: adTagOrig;
}

@keyframes adTagEdit {
  0%, 46% {
    opacity: 1;
  }
  47%, 66% {
    opacity: 0;
  }
  67%, 100% {
    opacity: 1;
  }
}
@keyframes adTagOrig {
  0%, 46% {
    opacity: 0;
  }
  47%, 66% {
    opacity: 1;
  }
  67%, 100% {
    opacity: 0;
  }
}
.ad.is-demo .ad__thumb {
  animation-duration: 2s;
  animation-timing-function: ease-out;
  animation-iteration-count: infinite;
}

.ad.is-demo #thB {
  animation-name: adThumbB;
}

.ad.is-demo #thC {
  animation-name: adThumbC;
}

.ad.is-demo #thS {
  animation-name: adThumbS;
}

@keyframes adThumbB {
  0%, 8% {
    transform: translate(-50%, -50%);
  }
  12%, 82% {
    transform: translate(-50%, -50%) translateX(16px);
  }
  86%, 100% {
    transform: translate(-50%, -50%);
  }
}
@keyframes adThumbC {
  0%, 8% {
    transform: translate(-50%, -50%);
  }
  12%, 82% {
    transform: translate(-50%, -50%) translateX(19px);
  }
  86%, 100% {
    transform: translate(-50%, -50%);
  }
}
@keyframes adThumbS {
  0%, 8% {
    transform: translate(-50%, -50%);
  }
  12%, 82% {
    transform: translate(-50%, -50%) translateX(26px);
  }
  86%, 100% {
    transform: translate(-50%, -50%);
  }
}
.ad.is-demo .ad__btn--ab {
  animation-name: adPress;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 1.4, 0.4, 1);
  animation-iteration-count: infinite;
}

@keyframes adPress {
  0%, 42% {
    transform: scale(1);
  }
  47% {
    transform: scale(0.88);
  }
  54%, 62% {
    transform: scale(1);
  }
  67% {
    transform: scale(0.88);
  }
  74%, 100% {
    transform: scale(1);
  }
}
.ad.is-demo .ad__realCode {
  color: transparent;
}

.ad.is-demo .ad__demoCode {
  display: block;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.ad.is-demo .ad__demoCode--a {
  animation-name: adCodeA;
}

.ad.is-demo .ad__demoCode--b {
  animation-name: adCodeB;
}

@keyframes adCodeA {
  0%, 9% {
    opacity: 1;
  }
  10%, 83% {
    opacity: 0;
  }
  84%, 100% {
    opacity: 1;
  }
}
@keyframes adCodeB {
  0%, 9% {
    opacity: 0;
  }
  10%, 83% {
    opacity: 1;
  }
  84%, 100% {
    opacity: 0;
  }
}
@media (max-width: 340px) {
  .ad {
    gap: 4px;
  }
  .ad__ctl {
    gap: 4px;
  }
  .ad__s {
    width: 88px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ad.is-demo .ad__ghost,
  .ad.is-demo .ad__orig,
  .ad.is-demo .ad__tagDemo,
  .ad.is-demo .ad__thumb,
  .ad.is-demo .ad__btn--ab,
  .ad.is-demo .ad__demoCode {
    animation: none !important;
  }
  .ad.is-demo .ad__ghost {
    filter: brightness(1.18) contrast(1.22) saturate(1.3) !important;
  }
  .ad.is-demo .ad__orig {
    opacity: 0 !important;
  }
  .ad.is-demo .ad__tagDemo--edit {
    opacity: 1 !important;
  }
  .ad.is-demo .ad__tagDemo--orig {
    opacity: 0 !important;
  }
  .ad.is-demo #thB {
    transform: translate(-50%, -50%) translateX(16px) !important;
  }
  .ad.is-demo #thC {
    transform: translate(-50%, -50%) translateX(19px) !important;
  }
  .ad.is-demo #thS {
    transform: translate(-50%, -50%) translateX(26px) !important;
  }
  .ad.is-demo .ad__demoCode--a {
    opacity: 0 !important;
  }
  .ad.is-demo .ad__demoCode--b {
    opacity: 1 !important;
  }
}

var ad = document.getElementById('ad');
var view = document.getElementById('view');
var tag = document.getElementById('tag');
var code = document.getElementById('code');
var abBtn = document.getElementById('abBtn');
var tracks = document.querySelectorAll('.ad__track');
var thumbs = { b: document.getElementById('thB'), c: document.getElementById('thC'), s: document.getElementById('thS') };
var value = { b: 1, c: 1, s: 1 };
var showOriginal = false;
var VOICE = '%v 倍';
var TAG_EDIT = '補正後';
var TAG_ORIG = '元画像';

// 가짜 사진 — 외부 파일 없이 그라디언트와 도형으로 합성한다. 필터·히스토그램이 보이도록 대비를 세게 준다
function paintPhoto(c, w, h) {
  var sky = c.createLinearGradient(0, 0, 0, h);
  sky.addColorStop(0, '#2f6df6'); sky.addColorStop(0.55, '#ff9ebb'); sky.addColorStop(1, '#ffd23f');
  c.fillStyle = sky; c.fillRect(0, 0, w, h);
  c.fillStyle = '#fff7e6';
  c.beginPath(); c.arc(w * 0.74, h * 0.28, h * 0.13, 0, Math.PI * 2); c.fill();
  // 곧은 수평선 하나 — 기울기 보정이 눈에 보이려면 비교할 직선이 있어야 한다
  c.fillStyle = 'rgba(23, 20, 26, 0.5)'; c.fillRect(0, Math.round(h * 0.66), w, 2);
  c.fillStyle = '#17141a';
  c.beginPath(); c.moveTo(0, h); c.lineTo(w * 0.34, h * 0.36); c.lineTo(w * 0.62, h); c.closePath(); c.fill();
  c.fillStyle = '#c2361a';
  c.beginPath(); c.moveTo(w * 0.46, h); c.lineTo(w * 0.78, h * 0.52); c.lineTo(w, h); c.closePath(); c.fill();
  for (var i = 0; i < 6; i++) { c.fillStyle = i % 2 ? '#fff7e6' : '#17141a'; c.fillRect(w * (0.08 + i * 0.07), h * (0.14 + (i % 3) * 0.06), 7, 7); }
}

function render() {
  // 슬라이더 셋이 filter 문자열 하나로 합쳐진다 — 순서가 곧 적용 순서다
  var chain = 'brightness(' + value.b.toFixed(2) + ') contrast(' + value.c.toFixed(2) + ') saturate(' + value.s.toFixed(2) + ')';
  view.style.filter = showOriginal ? 'none' : chain;
  code.textContent = chain;
  tag.textContent = showOriginal ? TAG_ORIG : TAG_EDIT;
  for (var i = 0; i < tracks.length; i++) {
    var key = tracks[i].getAttribute('data-k'), v = value[key];
    thumbs[key].style.left = ((v - 0.5) * 100) + '%';
    tracks[i].setAttribute('aria-valuenow', v.toFixed(2));
    tracks[i].setAttribute('aria-valuetext', VOICE.replace('%v', v.toFixed(2)));
  }
}

function setValue(key, next) {
  value[key] = Math.max(0.5, Math.min(1.5, Math.round(next * 100) / 100));
  ad.classList.remove('is-demo');
  render();
}

for (var i = 0; i < tracks.length; i++) {
  (function (el) {
    var key = el.getAttribute('data-k');
    function fromPointer(e) {
      var r = el.getBoundingClientRect();
      setValue(key, (e.clientX - r.left) / r.width + 0.5);
    }
    el.addEventListener('pointerdown', function (e) { el.setPointerCapture(e.pointerId); fromPointer(e); });
    el.addEventListener('pointermove', function (e) { if (e.buttons) { fromPointer(e); } });
    // 화살표 0.02, Shift 와 함께면 0.1 — 눈으로 맞추기 어려운 미세 보정은 키보드가 낫다
    el.addEventListener('keydown', function (e) {
      var step = e.shiftKey ? 0.1 : 0.02;
      if (e.key === 'ArrowLeft' || e.key === 'ArrowDown') { e.preventDefault(); setValue(key, value[key] - step); }
      else if (e.key === 'ArrowRight' || e.key === 'ArrowUp') { e.preventDefault(); setValue(key, value[key] + step); }
    });
  })(tracks[i]);
}

document.getElementById('resetBtn').addEventListener('click', function () {
  value.b = 1; value.c = 1; value.s = 1; showOriginal = false;
  abBtn.setAttribute('aria-pressed', 'false');
  ad.classList.remove('is-demo'); render();
});
abBtn.addEventListener('click', function () {
  showOriginal = !showOriginal;
  abBtn.setAttribute('aria-pressed', showOriginal ? 'true' : 'false');
  ad.classList.remove('is-demo'); render();
});

paintPhoto(view.getContext('2d'), view.width, view.height);
document.documentElement.style.setProperty('--photo', 'url(' + view.toDataURL() + ')');
render();

// ToneSliders — vanilla 판(run/295/demo/04-image-edit-adjust-sliders/index.html) 의 React 포트.
// 밝기·대비·채도 세 값이 filter 문자열 하나로 합쳐져 canvas 에 걸리고, 비교 버튼은 filter 를 none 으로
// 돌려 원본을 보여준다. 가짜 사진은 paintPhoto 가 그려 넣고, 그 toDataURL 을 --photo 로 내려
// 미리보기 유령 판 두 장이 같은 그림을 쓴다. 값·수치·키프레임은 vanilla 와 같다.
import { useEffect, useRef, useState } from "react";
import type { CSSProperties, PointerEvent as ReactPointerEvent } from "react";
import styles from "./ToneSliders.module.scss";

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

type Vars = CSSProperties & {
  "--duration"?: string;
  "--easing"?: string;
  "--color"?: string;
  "--photo"?: string;
};
type ToneKey = "b" | "c" | "s";
type Tone = { b: number; c: number; s: number };
// react 앰비언트에 KeyboardEvent 가 없다 — 키 핸들러가 실제로 쓰는 것만 지역 타입으로 선언한다
type KeyEvt = { key: string; shiftKey: boolean; preventDefault(): void };

const VOICE = "%v배";
const TAG_EDIT = "보정 후";
const TAG_ORIG = "원본";
const SLIDERS: { key: ToneKey; label: string; labelId: string; thumb: string }[] = [
  { key: "b", label: "밝기", labelId: "labB", thumb: styles.thumbB },
  { key: "c", label: "대비", labelId: "labC", thumb: styles.thumbC },
  { key: "s", label: "채도", labelId: "labS", thumb: styles.thumbS },
];

// 가짜 사진 — 외부 파일 없이 그라디언트와 도형으로 합성한다. 필터·히스토그램이 보이도록 대비를 세게 준다
function paintPhoto(c: CanvasRenderingContext2D, w: number, h: number): void {
  const sky = c.createLinearGradient(0, 0, 0, h);
  sky.addColorStop(0, "#2f6df6"); sky.addColorStop(0.55, "#ff9ebb"); sky.addColorStop(1, "#ffd23f");
  c.fillStyle = sky; c.fillRect(0, 0, w, h);
  c.fillStyle = "#fff7e6";
  c.beginPath(); c.arc(w * 0.74, h * 0.28, h * 0.13, 0, Math.PI * 2); c.fill();
  // 곧은 수평선 하나 — 기울기 보정이 눈에 보이려면 비교할 직선이 있어야 한다
  c.fillStyle = "rgba(23, 20, 26, 0.5)"; c.fillRect(0, Math.round(h * 0.66), w, 2);
  c.fillStyle = "#17141a";
  c.beginPath(); c.moveTo(0, h); c.lineTo(w * 0.34, h * 0.36); c.lineTo(w * 0.62, h); c.closePath(); c.fill();
  c.fillStyle = "#c2361a";
  c.beginPath(); c.moveTo(w * 0.46, h); c.lineTo(w * 0.78, h * 0.52); c.lineTo(w, h); c.closePath(); c.fill();
  for (let i = 0; i < 6; i++) { c.fillStyle = i % 2 ? "#fff7e6" : "#17141a"; c.fillRect(w * (0.08 + i * 0.07), h * (0.14 + (i % 3) * 0.06), 7, 7); }
}

export default function ToneSliders({
  duration = 2000,
  easing = "ease-out",
  color = "#17141a",
}: ToneSlidersProps) {
  const viewRef = useRef<HTMLCanvasElement | null>(null);
  const [tone, setTone] = useState<Tone>({ b: 1, c: 1, s: 1 });
  const [showOriginal, setShowOriginal] = useState(false);
  const [demo, setDemo] = useState(true);
  const [photo, setPhoto] = useState("");
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };
  if (photo) vars["--photo"] = `url(${photo})`;

  useEffect(() => {
    const canvas = viewRef.current;
    if (!canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;
    paintPhoto(ctx, canvas.width, canvas.height);
    setPhoto(canvas.toDataURL());
  }, []);

  // 슬라이더 셋이 filter 문자열 하나로 합쳐진다 — 순서가 곧 적용 순서다
  const chain = `brightness(${tone.b.toFixed(2)}) contrast(${tone.c.toFixed(2)}) saturate(${tone.s.toFixed(2)})`;

  function setValue(key: ToneKey, nextRaw: number): void {
    const v = Math.max(0.5, Math.min(1.5, Math.round(nextRaw * 100) / 100));
    setTone((prev) => {
      const next: Tone = { b: prev.b, c: prev.c, s: prev.s };
      next[key] = v;
      return next;
    });
    setDemo(false);
  }

  function fromPointer(key: ToneKey, event: ReactPointerEvent<HTMLDivElement>): void {
    const r = event.currentTarget.getBoundingClientRect();
    setValue(key, (event.clientX - r.left) / r.width + 0.5);
  }

  function onPointerDown(key: ToneKey, event: ReactPointerEvent<HTMLDivElement>): void {
    event.currentTarget.setPointerCapture(event.pointerId);
    fromPointer(key, event);
  }

  function onPointerMove(key: ToneKey, event: ReactPointerEvent<HTMLDivElement>): void {
    if (event.buttons) { fromPointer(key, event); }
  }

  // 화살표 0.02, Shift 와 함께면 0.1 — 눈으로 맞추기 어려운 미세 보정은 키보드가 낫다
  function onKeyDown(key: ToneKey, event: KeyEvt): void {
    const step = event.shiftKey ? 0.1 : 0.02;
    if (event.key === "ArrowLeft" || event.key === "ArrowDown") { event.preventDefault(); setValue(key, tone[key] - step); }
    else if (event.key === "ArrowRight" || event.key === "ArrowUp") { event.preventDefault(); setValue(key, tone[key] + step); }
  }

  function onReset(): void {
    setTone({ b: 1, c: 1, s: 1 });
    setShowOriginal(false);
    setDemo(false);
  }

  function onCompare(): void {
    setShowOriginal(!showOriginal);
    setDemo(false);
  }

  const cls = [styles.root, demo ? styles.isDemo : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls} style={vars}>
        <div className={styles.frame}>
          <canvas className={styles.view} ref={viewRef} width={320} height={200} role="img" aria-label="샘플 사진" style={{ filter: showOriginal ? "none" : chain }}></canvas>
          <span className={styles.ghost} aria-hidden="true"></span>
          <span className={styles.orig} aria-hidden="true"></span>
          <span className={styles.tag}>
            <span className={styles.real}>{showOriginal ? TAG_ORIG : TAG_EDIT}</span>
            <span className={`${styles.tagDemo} ${styles.tagDemoEdit}`} aria-hidden="true">보정 후</span>
            <span className={`${styles.tagDemo} ${styles.tagDemoOrig}`} aria-hidden="true">원본</span>
          </span>
        </div>
        <div className={styles.ctl}>
          {SLIDERS.map((s) => (
            <div className={styles.slider} key={s.key}>
              <span className={styles.lab} id={s.labelId}>{s.label}</span>
              <div
                className={styles.track}
                role="slider"
                tabIndex={0}
                aria-labelledby={s.labelId}
                aria-valuemin={0.5}
                aria-valuemax={1.5}
                aria-valuenow={Number(tone[s.key].toFixed(2))}
                aria-valuetext={VOICE.replace("%v", tone[s.key].toFixed(2))}
                onPointerDown={(e: ReactPointerEvent<HTMLDivElement>) => onPointerDown(s.key, e)}
                onPointerMove={(e: ReactPointerEvent<HTMLDivElement>) => onPointerMove(s.key, e)}
                onKeyDown={(e: KeyEvt) => onKeyDown(s.key, e)}
              >
                <span className={`${styles.thumb} ${s.thumb}`} style={{ left: `${(tone[s.key] - 0.5) * 100}%` }}></span>
              </div>
            </div>
          ))}
        </div>
        <div className={styles.foot}>
          <button type="button" className={styles.btn} onClick={onReset}>초기화</button>
          <button type="button" className={`${styles.btn} ${styles.btnAb}`} aria-pressed={showOriginal} onClick={onCompare}><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" className={styles.ico} aria-hidden="true"><g fill="currentColor"><path d="M80 136a24 24 0 1 1-24-24a24 24 0 0 1 24 24m48-72a24 24 0 1 0 24 24a24 24 0 0 0-24-24m72 80a24 24 0 1 0 24 24a24 24 0 0 0-24-24" opacity=".2"/><path d="M64 105V40a8 8 0 0 0-16 0v65a32 32 0 0 0 0 62v49a8 8 0 0 0 16 0v-49a32 32 0 0 0 0-62m-8 47a16 16 0 1 1 16-16a16 16 0 0 1-16 16m80-95V40a8 8 0 0 0-16 0v17a32 32 0 0 0 0 62v97a8 8 0 0 0 16 0v-97a32 32 0 0 0 0-62m-8 47a16 16 0 1 1 16-16a16 16 0 0 1-16 16m104 64a32.06 32.06 0 0 0-24-31V40a8 8 0 0 0-16 0v97a32 32 0 0 0 0 62v17a8 8 0 0 0 16 0v-17a32.06 32.06 0 0 0 24-31m-32 16a16 16 0 1 1 16-16a16 16 0 0 1-16 16"/></g></svg><span>비교</span></button>
          <span className={styles.codes}>
            <code className={styles.realCode}>{chain}</code>
            <code className={`${styles.demoCode} ${styles.demoCodeA}`} aria-hidden="true">brightness(1.00) contrast(1.00) saturate(1.00)</code>
            <code className={`${styles.demoCode} ${styles.demoCodeB}`} aria-hidden="true">brightness(1.18) contrast(1.22) saturate(1.30)</code>
          </span>
        </div>
      </div>
    </main>
  );
}