07Auto-crop export

<main class="stage">
<div class="ex is-demo" id="ex">
  <div class="ex__card">
    <div class="ex__bar">
      <p class="ex__label"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor" class="ex__ico" aria-hidden="true"><path d="M67.41,142.56C35.71,129.52,45.41,32.07,78,32,111.82,32.05,92,90.26,67.41,142.56Z" opacity="0.2"/><path d="M232,168H63.86c2.66-5.24,5.33-10.63,8-16.11,14.94,1.65,32.58-8.78,52.66-31.14,5,13.46,14.45,30.93,30.58,31.25,9.09.18,18.11-5.2,27.42-16.37C189.31,143.75,203.3,152,232,152a8,8,0,0,0,0-16c-30.43,0-39.43-10.45-40-16.11a7.67,7.67,0,0,0-5.46-7.75,8.14,8.14,0,0,0-9.25,3.49C165.23,134.17,158,136.06,155.38,136c-8.26-.16-16.66-19.52-19.54-33.42a8,8,0,0,0-14.09-3.37C101.54,124.55,88,133.08,79.57,135.29,88.06,116.42,94.4,99.85,98.46,85.9c6.82-23.44,7.32-39.83,1.51-50.1-3-5.38-9.34-11.8-22.06-11.8C61.85,24,49.18,39.18,43.14,65.65c-3.59,15.71-4.18,33.21-1.62,48s7.87,25.55,15.59,31.94c-3.73,7.72-7.53,15.26-11.23,22.41H24a8,8,0,0,0,0,16H37.41c-11.32,21-20.12,35.64-20.26,35.88a8,8,0,1,0,13.71,8.24c.15-.26,11.27-18.79,24.7-44.12H232a8,8,0,0,0,0-16ZM58.74,69.21C62.72,51.74,70.43,40,77.91,40c5.33,0,7.1,1.86,8.13,3.67,3,5.33,6.52,24.19-21.66,86.39C56.12,118.78,53.31,93,58.74,69.21Z"/></svg><span>Export signature</span></p>
      <button type="button" class="ex__btn" id="exportBtn"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor" class="ex__ico" aria-hidden="true"><path d="M216,48V208H40V48A16,16,0,0,1,56,32H200A16,16,0,0,1,216,48Z" opacity="0.2"/><path d="M224,144v64a8,8,0,0,1-8,8H40a8,8,0,0,1-8-8V144a8,8,0,0,1,16,0v56H208V144a8,8,0,0,1,16,0Zm-101.66,5.66a8,8,0,0,0,11.32,0l40-40a8,8,0,0,0-11.32-11.32L136,124.69V32a8,8,0,0,0-16,0v92.69L93.66,98.34a8,8,0,0,0-11.32,11.32Z"/></svg><span>Export as PNG</span></button>
    </div>
    <div class="ex__body">
      <div class="ex__pad" id="pad">
        <canvas class="ex__ink" id="ink" role="img" aria-label="Signature box"></canvas>
        <!-- 미리보기용 Signature — canvas 에 그려지는 SAMPLE 과 같은 좌표를 중점 2차 곡선으로 옮긴 것 -->
        <svg class="ex__ghost" viewBox="0 0 200 100" preserveAspectRatio="none" aria-hidden="true">
          <path class="ex__stroke" d="M30,56 Q30,56 33,46 Q36,36 41,31 Q46,26 50,31 Q54,36 52,44 Q50,52 47,56 Q44,60 48,59 Q52,58 59,52 Q66,46 72,39 Q78,32 82,30 Q86,28 88,34 Q90,40 93,46 Q96,52 100,53"/>
          <path class="ex__stroke" d="M112,50 Q112,50 117,42 Q122,34 127,30 Q132,26 136,29 Q140,32 138,39 Q136,46 140,47 Q144,48 150,43 Q156,38 160,33"/>
          <path class="ex__stroke" d="M36,70 Q36,70 53,72 Q70,74 90,75 Q110,76 130,74 Q150,72 161,68"/>
        </svg>
        <span class="ex__crop" id="crop" aria-hidden="true"></span>
      </div>
      <div class="ex__out">
        <span class="ex__outLabel">Preview</span>
        <div class="ex__frame">
          <span class="ex__hint">The result appears here</span>
          <img class="ex__img" id="out" alt="Signature preview with margin trimmed">
          <!-- Preview 루프에서만 보이는 결과 사본 — viewBox 가 Ink 바깥선이라 잘린 그림이 된다 -->
          <svg class="ex__thumb" viewBox="21 19 149 65" aria-hidden="true">
            <path class="ex__stroke" d="M30,56 Q30,56 33,46 Q36,36 41,31 Q46,26 50,31 Q54,36 52,44 Q50,52 47,56 Q44,60 48,59 Q52,58 59,52 Q66,46 72,39 Q78,32 82,30 Q86,28 88,34 Q90,40 93,46 Q96,52 100,53"/>
            <path class="ex__stroke" d="M112,50 Q112,50 117,42 Q122,34 127,30 Q132,26 136,29 Q140,32 138,39 Q136,46 140,47 Q144,48 150,43 Q156,38 160,33"/>
            <path class="ex__stroke" d="M36,70 Q36,70 53,72 Q70,74 90,75 Q110,76 130,74 Q150,72 161,68"/>
          </svg>
        </div>
      </div>
    </div>
    <p class="ex__live">
      <span class="ex__liveReal" id="live" aria-live="polite">Press export to trim the outer margin</span>
      <span class="ex__liveDemo ex__liveDemo--before" aria-hidden="true">Press export to trim the outer margin</span>
      <span class="ex__liveDemo ex__liveDemo--after" aria-hidden="true">Preview with the outer margin trimmed</span>
    </p>
  </div>
</div>
</main>

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

// 여백 자동 크롭 내보내기 — 실제 동작은 canvas 2D 가 한다. getImageData 로 알파 채널을 훑어
// 잉크가 있는 픽셀의 바운딩 박스를 구하고, 그 크기의 보조 canvas 에 drawImage 로 잘라 담은 뒤
// toDataURL('image/png') 를 미리보기 <img> 에 넣는다. 배경을 칠하지 않으니 알파가 남아 투명 배경이 된다.
// 격자 미리보기(.is-demo)는 canvas 를 감추고 같은 장면을 CSS @keyframes 로 재현한다 —
// demo.py 는 CSS 애니메이션 시계로 프레임을 뽑으므로 JS 로 그린 그림은 24장이 전부 같다.

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

@include stage($stage-yellow);

.ex { display: flex; justify-content: center; width: 100%; }
.ex__card {
  width: min(100%, 340px); background: $stage-paper; border-radius: $r-card;
  box-shadow: $shadow-raised; overflow: hidden;
}
.ex__bar {
  display: flex; align-items: center; justify-content: space-between; gap: $sp-2;
  background: $subject-ink; padding: $sp-2 $sp-3;
}
.ex__label {
  display: flex; align-items: center; gap: $sp-1; margin: 0;
  font-weight: 800; font-size: clamp(9px, 2.4vw, 11px); line-height: 1.3; color: $stage-paper;
}
.ex__ico { width: 14px; height: 14px; flex: 0 0 auto; }
.ex__btn {
  display: flex; align-items: center; gap: $sp-1; cursor: pointer;
  border: 1px solid $subject-blue; background: $subject-blue; color: $stage-paper;
  border-radius: $r-pill; font-family: inherit; font-weight: 700;
  font-size: clamp(9px, 2.4vw, 10px); padding: $sp-1 $sp-2; line-height: 1.3;
}
.ex__btn:focus-visible { outline: 3px solid $stage-paper; outline-offset: 2px; }

.ex__body { display: grid; grid-template-columns: 1.6fr 1fr; gap: $sp-2; padding: $sp-2; }
.ex__pad {
  position: relative; background: $subject-cream; border-radius: $r-sm;
  aspect-ratio: 200 / 100; touch-action: none; overflow: hidden;
}
.ex__ink, .ex__ghost { position: absolute; inset: 0; width: 100%; height: 100%; }
.ex__ghost { display: none; }
.ex__stroke { fill: none; stroke: $color; stroke-width: 4; stroke-linecap: round; stroke-linejoin: round; }
// 크롭 테두리 — 네 변이 잉크 바깥선까지 함께 조여든다. 1px 점선을 scale 로 줄이면 선과 점이 같이
// 굵어지므로 여기서는 절대배치 오버레이의 변(inset)을 움직인다. 실사용에서는 JS 가 잰 바운딩 박스를
// 퍼센트로 넣어 같은 자리로 조인다
.ex__crop {
  position: absolute; inset: 0; pointer-events: none;
  border: 1px dashed $subject-blue; border-radius: $r-xs;
  transition: inset $dur-base $ease-spring;
}

.ex__out { display: flex; flex-direction: column; gap: $sp-1; min-width: 0; }
.ex__outLabel { font-weight: 800; font-size: 9px; line-height: 1.3; color: rgba(23, 20, 26, .72); }
.ex__frame {
  position: relative; flex: 1 1 auto; min-height: 0; display: grid; place-items: center;
  border: 1px solid rgba(23, 20, 26, .16); border-radius: $r-sm; overflow: hidden;
  // 투명 배경을 뜻하는 체크무늬
  background-color: $stage-paper;
  background-image: repeating-conic-gradient(rgba(23, 20, 26, .1) 0% 25%, transparent 0% 50%);
  background-size: 12px 12px;
}
.ex__hint {
  padding: 0 $sp-1; text-align: center; font-weight: 700;
  font-size: clamp(8px, 2.2vw, 9px); line-height: 1.3; color: rgba(23, 20, 26, .72);
}
.ex__img { display: none; max-width: 100%; max-height: 100%; }
.ex.has-out .ex__img { display: block; }
.ex.has-out .ex__hint { display: none; }
// 결과 사본은 축소되어 들어가므로 선을 조금 굵게 — 원본과 같은 굵기로 보이고 등장 프레임도 또렷하다
.ex__thumb { display: none; position: absolute; inset: $sp-1; }
.ex__thumb .ex__stroke { stroke-width: 6; }

.ex__live {
  position: relative; margin: 0; padding: 0 $sp-3 $sp-2; font-weight: 700;
  font-size: clamp(8px, 2.2vw, 10px); line-height: 1.3; color: rgba(23, 20, 26, .72);
}
.ex__liveDemo { display: none; position: absolute; left: $sp-3; top: 0; }

// ── 미리보기 루프: 0~10% 버튼이 자기 중심에서 눌리고, 12~44% 크롭 테두리가 판 전체에서
//    잉크 바깥선까지 네 변이 함께 조여든다. 46% 에 잘린 결과가 오른쪽 칸에 컷으로 나타나
//    62% 까지 scale(.78) → scale(1) 로 팝한다 — 앞 프레임과의 면적차가 여기서 가장 커서 poster 가 된다.
//    64~81% 는 「여백을 잘라냈다」 문구가 컷으로 바뀌며 올라오고, 68~84% 결과가 작아지다 꺼지고,
//    84~92% 테두리가 판 전체로 벌어져 시작 상태로 돌아온다 (마지막 프레임은 2초의 95.8% 지점이다).
.ex.is-demo .ex__ink { visibility: hidden; }
.ex.is-demo .ex__ghost { display: block; }
.ex.is-demo .ex__thumb { display: block; }

.ex.is-demo .ex__btn {
  animation-name: exPress;
  animation-duration: $duration;
  animation-timing-function: $ease-pop;
  animation-iteration-count: infinite;
}
@keyframes exPress {
  0% { transform: scale(1); }
  4% { transform: scale(.9); }
  10%, 100% { transform: scale(1); }
}

.ex.is-demo .ex__crop {
  animation-name: exCrop;
  animation-duration: $duration;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
@keyframes exCrop {
  0%, 12% { inset: 0; }
  44%, 84% { inset: 19% 15% 16% 11%; }
  92%, 100% { inset: 0; }
}

// 결과는 나타날 때만 컷(steps)이고 커지는 건 자기 중심 팝이다 — transform-origin 은 기본값 50% 50%.
// 등장은 46% 에 이미 scale(.78) 인 채로 컷해 한 칸에 거의 다 나타나고(면적차 최대 = poster),
// 퇴장은 68~82% 에 걸쳐 scale(.5) 까지 천천히 작아진 뒤 84% 에 꺼져 면적차가 등장 때보다 작다.
// 실측 2026-09-12: 퇴장을 크롭 테두리 벌어짐과 겹쳐 두면 그쪽이 poster 를 가져갔다 (1.69 대 1.13)
.ex.is-demo .ex__thumb {
  animation-name: exShow, exPop, exWipe;
  animation-duration: $duration, $duration, $duration;
  animation-timing-function: steps(1, end), $ease-pop, $easing;
  animation-iteration-count: infinite, infinite, infinite;
  animation-fill-mode: backwards, backwards, backwards;
}
@keyframes exShow {
  0%, 45% { opacity: 0; }
  46%, 100% { opacity: 1; }
}
@keyframes exPop {
  0%, 45% { transform: scale(.86); }
  62%, 100% { transform: scale(1); }
}
// 퇴장은 clip-path 위프 — 프레임마다 지워지는 띠만 변해 면적차가 등장의 컷보다 작다.
// 위프는 컷(steps)과 같은 애니메이션에 묶지 않는다 — steps 는 clip-path 보간을 죽인다
@keyframes exWipe {
  0%, 70% { clip-path: inset(0 0 0 0); }
  84%, 100% { clip-path: inset(0 100% 0 0); }
}

.ex.is-demo .ex__hint {
  animation-name: exHint;
  animation-duration: $duration;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
@keyframes exHint {
  0%, 45% { opacity: 1; }
  46%, 85% { opacity: 0; }
  86%, 100% { opacity: 1; }
}

// 안내 문구는 칸 두 개를 steps(1, end) 로 갈아 끼운다 — 반투명 겹침이 없다.
// 바뀐 문구는 컷 옆에 작은 올라오기를 함께 둬 컷만으로는 비는 프레임을 채운다
.ex.is-demo .ex__liveReal { color: transparent; }
.ex.is-demo .ex__liveDemo { display: block; }
.ex.is-demo .ex__liveDemo--before {
  animation-name: exSayBefore;
  animation-duration: $duration;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
.ex.is-demo .ex__liveDemo--after {
  animation-name: exSayAfter;
  animation-duration: $duration;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}
// 문구가 되돌아오는 컷은 94% — 크롭 테두리가 다 벌어진 뒤라 다른 움직임과 겹치지 않고,
// 마지막 프레임(95.8%)이 첫 프레임과 같은 문구가 되어 루프 이음매도 맞는다
@keyframes exSayBefore {
  0%, 63% { opacity: 1; }
  64%, 93% { opacity: 0; }
  94%, 100% { opacity: 1; }
}
@keyframes exSayAfter {
  0%, 63% { opacity: 0; }
  64%, 93% { opacity: 1; }
  94%, 100% { opacity: 0; }
}

@media (max-width: 340px) {
  .ex__bar { padding: $sp-1 $sp-2; }
  .ex__body { gap: $sp-1; padding: $sp-1; }
  .ex__live { padding: 0 $sp-2 $sp-1; }
  .ex__liveDemo { left: $sp-2; }
}

@media (prefers-reduced-motion: reduce) {
  .ex.is-demo .ex__btn,
  .ex.is-demo .ex__crop,
  .ex.is-demo .ex__thumb,
  .ex.is-demo .ex__hint,
  .ex.is-demo .ex__liveDemo { animation: none !important; }
  // 움직임 없이 「잘라낸 결과가 나와 있는」 최종 상태로 세운다
  .ex.is-demo .ex__crop { inset: 19% 15% 16% 11% !important; }
  .ex.is-demo .ex__thumb {
    opacity: 1 !important; transform: scale(1) !important; clip-path: inset(0 0 0 0) !important;
  }
  .ex.is-demo .ex__hint { opacity: 0 !important; }
  .ex.is-demo .ex__liveDemo--before { opacity: 0 !important; }
  .ex.is-demo .ex__liveDemo--after { 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: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ex {
  display: flex;
  justify-content: center;
  width: 100%;
}

.ex__card {
  width: min(100%, 340px);
  background: #ffffff;
  border-radius: 16px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  overflow: hidden;
}

.ex__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  background: #17141a;
  padding: 8px 12px;
}

.ex__label {
  display: flex;
  align-items: center;
  gap: 4px;
  margin: 0;
  font-weight: 800;
  font-size: clamp(9px, 2.4vw, 11px);
  line-height: 1.3;
  color: #ffffff;
}

.ex__ico {
  width: 14px;
  height: 14px;
  flex: 0 0 auto;
}

.ex__btn {
  display: flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  border: 1px solid #2f6df6;
  background: #2f6df6;
  color: #ffffff;
  border-radius: 999px;
  font-family: inherit;
  font-weight: 700;
  font-size: clamp(9px, 2.4vw, 10px);
  padding: 4px 8px;
  line-height: 1.3;
}

.ex__btn:focus-visible {
  outline: 3px solid #ffffff;
  outline-offset: 2px;
}

.ex__body {
  display: grid;
  grid-template-columns: 1.6fr 1fr;
  gap: 8px;
  padding: 8px;
}

.ex__pad {
  position: relative;
  background: #fff7e6;
  border-radius: 8px;
  aspect-ratio: 200/100;
  touch-action: none;
  overflow: hidden;
}

.ex__ink, .ex__ghost {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.ex__ghost {
  display: none;
}

.ex__stroke {
  fill: none;
  stroke: #17141a;
  stroke-width: 4;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.ex__crop {
  position: absolute;
  inset: 0;
  pointer-events: none;
  border: 1px dashed #2f6df6;
  border-radius: 4px;
  transition: inset 300ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.ex__out {
  display: flex;
  flex-direction: column;
  gap: 4px;
  min-width: 0;
}

.ex__outLabel {
  font-weight: 800;
  font-size: 9px;
  line-height: 1.3;
  color: rgba(23, 20, 26, 0.72);
}

.ex__frame {
  position: relative;
  flex: 1 1 auto;
  min-height: 0;
  display: grid;
  place-items: center;
  border: 1px solid rgba(23, 20, 26, 0.16);
  border-radius: 8px;
  overflow: hidden;
  background-color: #ffffff;
  background-image: repeating-conic-gradient(rgba(23, 20, 26, 0.1) 0% 25%, transparent 0% 50%);
  background-size: 12px 12px;
}

.ex__hint {
  padding: 0 4px;
  text-align: center;
  font-weight: 700;
  font-size: clamp(8px, 2.2vw, 9px);
  line-height: 1.3;
  color: rgba(23, 20, 26, 0.72);
}

.ex__img {
  display: none;
  max-width: 100%;
  max-height: 100%;
}

.ex.has-out .ex__img {
  display: block;
}

.ex.has-out .ex__hint {
  display: none;
}

.ex__thumb {
  display: none;
  position: absolute;
  inset: 4px;
}

.ex__thumb .ex__stroke {
  stroke-width: 6;
}

.ex__live {
  position: relative;
  margin: 0;
  padding: 0 12px 8px;
  font-weight: 700;
  font-size: clamp(8px, 2.2vw, 10px);
  line-height: 1.3;
  color: rgba(23, 20, 26, 0.72);
}

.ex__liveDemo {
  display: none;
  position: absolute;
  left: 12px;
  top: 0;
}

.ex.is-demo .ex__ink {
  visibility: hidden;
}

.ex.is-demo .ex__ghost {
  display: block;
}

.ex.is-demo .ex__thumb {
  display: block;
}

.ex.is-demo .ex__btn {
  animation-name: exPress;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 1.4, 0.4, 1);
  animation-iteration-count: infinite;
}

@keyframes exPress {
  0% {
    transform: scale(1);
  }
  4% {
    transform: scale(0.9);
  }
  10%, 100% {
    transform: scale(1);
  }
}
.ex.is-demo .ex__crop {
  animation-name: exCrop;
  animation-duration: 2s;
  animation-timing-function: ease-out;
  animation-iteration-count: infinite;
}

@keyframes exCrop {
  0%, 12% {
    inset: 0;
  }
  44%, 84% {
    inset: 19% 15% 16% 11%;
  }
  92%, 100% {
    inset: 0;
  }
}
.ex.is-demo .ex__thumb {
  animation-name: exShow, exPop, exWipe;
  animation-duration: 2s, 2s, 2s;
  animation-timing-function: steps(1, end), cubic-bezier(0.2, 1.4, 0.4, 1), ease-out;
  animation-iteration-count: infinite, infinite, infinite;
  animation-fill-mode: backwards, backwards, backwards;
}

@keyframes exShow {
  0%, 45% {
    opacity: 0;
  }
  46%, 100% {
    opacity: 1;
  }
}
@keyframes exPop {
  0%, 45% {
    transform: scale(0.86);
  }
  62%, 100% {
    transform: scale(1);
  }
}
@keyframes exWipe {
  0%, 70% {
    clip-path: inset(0 0 0 0);
  }
  84%, 100% {
    clip-path: inset(0 100% 0 0);
  }
}
.ex.is-demo .ex__hint {
  animation-name: exHint;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes exHint {
  0%, 45% {
    opacity: 1;
  }
  46%, 85% {
    opacity: 0;
  }
  86%, 100% {
    opacity: 1;
  }
}
.ex.is-demo .ex__liveReal {
  color: transparent;
}

.ex.is-demo .ex__liveDemo {
  display: block;
}

.ex.is-demo .ex__liveDemo--before {
  animation-name: exSayBefore;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

.ex.is-demo .ex__liveDemo--after {
  animation-name: exSayAfter;
  animation-duration: 2s;
  animation-timing-function: steps(1, end);
  animation-iteration-count: infinite;
}

@keyframes exSayBefore {
  0%, 63% {
    opacity: 1;
  }
  64%, 93% {
    opacity: 0;
  }
  94%, 100% {
    opacity: 1;
  }
}
@keyframes exSayAfter {
  0%, 63% {
    opacity: 0;
  }
  64%, 93% {
    opacity: 1;
  }
  94%, 100% {
    opacity: 0;
  }
}
@media (max-width: 340px) {
  .ex__bar {
    padding: 4px 8px;
  }
  .ex__body {
    gap: 4px;
    padding: 4px;
  }
  .ex__live {
    padding: 0 8px 4px;
  }
  .ex__liveDemo {
    left: 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ex.is-demo .ex__btn,
  .ex.is-demo .ex__crop,
  .ex.is-demo .ex__thumb,
  .ex.is-demo .ex__hint,
  .ex.is-demo .ex__liveDemo {
    animation: none !important;
  }
  .ex.is-demo .ex__crop {
    inset: 19% 15% 16% 11% !important;
  }
  .ex.is-demo .ex__thumb {
    opacity: 1 !important;
    transform: scale(1) !important;
    clip-path: inset(0 0 0 0) !important;
  }
  .ex.is-demo .ex__hint {
    opacity: 0 !important;
  }
  .ex.is-demo .ex__liveDemo--before {
    opacity: 0 !important;
  }
  .ex.is-demo .ex__liveDemo--after {
    opacity: 1 !important;
  }
}

var ex = document.getElementById('ex');
var pad = document.getElementById('pad');
var ink = document.getElementById('ink');
var out = document.getElementById('out');
var crop = document.getElementById('crop');
var live = document.getElementById('live');
var ctx = ink.getContext('2d');
var strokes = [], current = null;
var TRIM_LABEL = 'Preview with %wpx by %hpx of margin trimmed';
var EMPTY_LABEL = 'The signature is empty, nothing to trim';
// 마운트 때 깔아 두는 예시 Signature — 200×100 칸 기준 좌표. 판 크기에 맞춰 늘려 그린다
var SAMPLE = [
  [[30, 56], [36, 36], [46, 26], [54, 36], [50, 52], [44, 60], [52, 58], [66, 46], [78, 32], [86, 28], [90, 40], [96, 52], [104, 54]],
  [[112, 50], [122, 34], [132, 26], [140, 32], [136, 46], [144, 48], [156, 38], [164, 28]],
  [[36, 70], [70, 74], [110, 76], [150, 72], [172, 64]]
];

// 고DPI 대응 — 배킹 스토어를 devicePixelRatio 배로 키우고 좌표계는 CSS 픽셀 그대로 쓴다
function resize() {
  var r = pad.getBoundingClientRect(), dpr = window.devicePixelRatio || 1;
  ink.width = Math.round(r.width * dpr);
  ink.height = Math.round(r.height * dpr);
  ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
  repaint();
}

function drawPoints(pts) {
  ctx.beginPath();
  ctx.moveTo(pts[0][0], pts[0][1]);
  for (var i = 1; i < pts.length; i++) {
    // 두 점의 중점을 제어점으로 삼아 꺾임을 둥글게 잇는다
    ctx.quadraticCurveTo(pts[i - 1][0], pts[i - 1][1], (pts[i][0] + pts[i - 1][0]) / 2, (pts[i][1] + pts[i - 1][1]) / 2);
  }
  ctx.stroke();
}

function repaint() {
  var r = pad.getBoundingClientRect();
  ctx.clearRect(0, 0, ink.width, ink.height);
  ctx.lineCap = 'round';
  ctx.lineJoin = 'round';
  ctx.lineWidth = 4;
  ctx.strokeStyle = '#17141a';
  for (var s = 0; s < SAMPLE.length; s++) {
    var scaled = [];
    for (var i = 0; i < SAMPLE[s].length; i++) {
      scaled.push([SAMPLE[s][i][0] * r.width / 200, SAMPLE[s][i][1] * r.height / 100]);
    }
    drawPoints(scaled);
  }
  for (var u = 0; u < strokes.length; u++) { drawPoints(strokes[u]); }
}

function exportCrop() {
  ex.classList.remove('is-demo');
  var pixels = ctx.getImageData(0, 0, ink.width, ink.height);
  var data = pixels.data;
  var minX = ink.width, minY = ink.height, maxX = -1, maxY = -1;
  for (var y = 0; y < ink.height; y++) {
    for (var x = 0; x < ink.width; x++) {
      // 배경을 칠하지 않았으므로 잉크가 없는 자리는 알파가 0 이다 — 알파 채널만 훑으면 바운딩 박스가 나온다
      if (data[(y * ink.width + x) * 4 + 3] > 8) {
        if (x < minX) { minX = x; }
        if (x > maxX) { maxX = x; }
        if (y < minY) { minY = y; }
        if (y > maxY) { maxY = y; }
      }
    }
  }
  if (maxX < 0) { live.textContent = EMPTY_LABEL; return; }
  var dpr = window.devicePixelRatio || 1;
  var edge = Math.round(6 * dpr);
  minX = Math.max(0, minX - edge);
  minY = Math.max(0, minY - edge);
  maxX = Math.min(ink.width - 1, maxX + edge);
  maxY = Math.min(ink.height - 1, maxY + edge);
  var sw = maxX - minX + 1, sh = maxY - minY + 1;
  // 잰 바운딩 박스를 퍼센트로 바꿔 크롭 테두리를 그 자리로 조인다 — 무엇이 잘렸는지 눈에 보인다
  crop.style.inset = (minY / ink.height * 100).toFixed(1) + '% ' +
    ((ink.width - maxX - 1) / ink.width * 100).toFixed(1) + '% ' +
    ((ink.height - maxY - 1) / ink.height * 100).toFixed(1) + '% ' +
    (minX / ink.width * 100).toFixed(1) + '%';
  var cropped = document.createElement('canvas');
  cropped.width = sw;
  cropped.height = sh;
  // 배경을 칠하지 않고 잘린 자리만 옮기므로 알파가 그대로 남는다 — 투명 배경 PNG 가 된다
  cropped.getContext('2d').drawImage(ink, minX, minY, sw, sh, 0, 0, sw, sh);
  // 데모는 iframe 안에서 도니 <a download> 는 동작하지 않는다. 결과는 Preview <img> 까지만 보여 준다
  out.src = cropped.toDataURL('image/png');
  ex.classList.add('has-out');
  live.textContent = TRIM_LABEL
    .replace('%w', String(Math.round((ink.width - sw) / dpr)))
    .replace('%h', String(Math.round((ink.height - sh) / dpr)));
}

function toLocal(e) {
  var r = ink.getBoundingClientRect();
  return [e.clientX - r.left, e.clientY - r.top];
}

pad.addEventListener('pointerdown', function (e) {
  ex.classList.remove('is-demo');
  crop.style.inset = '';
  current = [toLocal(e)];
  strokes.push(current);
  pad.setPointerCapture(e.pointerId);
});
pad.addEventListener('pointermove', function (e) {
  if (!current) { return; }
  current.push(toLocal(e));
  repaint();
});
window.addEventListener('pointerup', function () { current = null; });
document.getElementById('exportBtn').addEventListener('click', exportCrop);
window.addEventListener('resize', resize);
resize();

// SignatureExport — vanilla 판(run/287/demo/07-signature-export-crop/index.html) 의 React 포트.
// getImageData 로 알파 채널을 훑어 잉크의 바운딩 박스를 구하고, 그 크기의 보조 canvas 에 drawImage 로
// 잘라 담은 뒤 toDataURL('image/png') 을 미리보기 <img> 에 넣는다. 배경을 칠하지 않으니 알파가
// 그대로 남아 투명 배경 PNG 가 된다. 값·수치·키프레임은 vanilla 와 같다.
import { useCallback, useEffect, useRef, useState } from "react";
import type { CSSProperties, PointerEvent as ReactPointerEvent } from "react";
import styles from "./SignatureExport.module.scss";

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

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type Point = [number, number];
// useRef 는 T | null 을 돌려주므로, 초기값이 있는 상자는 이 타입으로 좁혀 쓴다
type Box<T> = { current: T };

const TRIM_LABEL = "여백 가로 %wpx · 세로 %hpx 를 잘라낸 미리보기입니다";
const EMPTY_LABEL = "서명이 비어 있어 잘라낼 것이 없습니다";
const READY_LABEL = "내보내기를 누르면 바깥 여백을 잘라냅니다";
// 마운트 때 깔아 두는 예시 서명 — 200×100 칸 기준 좌표. 판 크기에 맞춰 늘려 그린다
const SAMPLE: Point[][] = [
  [[30, 56], [36, 36], [46, 26], [54, 36], [50, 52], [44, 60], [52, 58], [66, 46], [78, 32], [86, 28], [90, 40], [96, 52], [104, 54]],
  [[112, 50], [122, 34], [132, 26], [140, 32], [136, 46], [144, 48], [156, 38], [164, 28]],
  [[36, 70], [70, 74], [110, 76], [150, 72], [172, 64]],
];

function drawPoints(ctx: CanvasRenderingContext2D, pts: Point[]): void {
  ctx.beginPath();
  ctx.moveTo(pts[0][0], pts[0][1]);
  for (let i = 1; i < pts.length; i++) {
    // 두 점의 중점을 제어점으로 삼아 꺾임을 둥글게 잇는다
    ctx.quadraticCurveTo(pts[i - 1][0], pts[i - 1][1], (pts[i][0] + pts[i - 1][0]) / 2, (pts[i][1] + pts[i - 1][1]) / 2);
  }
  ctx.stroke();
}

export default function SignatureExport({
  duration = 2000,
  easing = "ease-out",
  color = "#17141a",
}: SignatureExportProps) {
  const padRef = useRef<HTMLDivElement | null>(null);
  const inkRef = useRef<HTMLCanvasElement | null>(null);
  const strokesRef = useRef<Point[][]>([]) as Box<Point[][]>;
  const currentRef = useRef<Point[] | null>(null);
  const [demo, setDemo] = useState(true);
  const [src, setSrc] = useState("");
  const [cropInset, setCropInset] = useState("");
  const [message, setMessage] = useState(READY_LABEL);
  const vars: Vars = { "--duration": `${duration}ms`, "--easing": easing, "--color": color };

  const repaint = useCallback(() => {
    const pad = padRef.current;
    const canvas = inkRef.current;
    if (!pad || !canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;
    const r = pad.getBoundingClientRect();
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.lineCap = "round";
    ctx.lineJoin = "round";
    ctx.lineWidth = 4;
    ctx.strokeStyle = color;
    for (const pts of SAMPLE) {
      const scaled: Point[] = pts.map((p) => [p[0] * r.width / 200, p[1] * r.height / 100]);
      drawPoints(ctx, scaled);
    }
    for (const pts of strokesRef.current) drawPoints(ctx, pts);
  }, [color]);

  // 고DPI 대응 — 배킹 스토어를 devicePixelRatio 배로 키우고 좌표계는 CSS 픽셀 그대로 쓴다
  const resize = useCallback(() => {
    const pad = padRef.current;
    const canvas = inkRef.current;
    if (!pad || !canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;
    const r = pad.getBoundingClientRect();
    const dpr = window.devicePixelRatio || 1;
    canvas.width = Math.round(r.width * dpr);
    canvas.height = Math.round(r.height * dpr);
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    repaint();
  }, [repaint]);

  useEffect(() => {
    resize();
    window.addEventListener("resize", resize);
    return () => window.removeEventListener("resize", resize);
  }, [resize]);

  useEffect(() => {
    function onUp(): void {
      currentRef.current = null;
    }
    window.addEventListener("pointerup", onUp);
    return () => window.removeEventListener("pointerup", onUp);
  }, []);

  function exportCrop(): void {
    setDemo(false);
    const canvas = inkRef.current;
    if (!canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;
    const pixels = ctx.getImageData(0, 0, canvas.width, canvas.height);
    const data = pixels.data;
    let minX = canvas.width;
    let minY = canvas.height;
    let maxX = -1;
    let maxY = -1;
    for (let y = 0; y < canvas.height; y++) {
      for (let x = 0; x < canvas.width; x++) {
        // 배경을 칠하지 않았으므로 잉크가 없는 자리는 알파가 0 이다 — 알파 채널만 훑으면 바운딩 박스가 나온다
        if (data[(y * canvas.width + x) * 4 + 3] > 8) {
          if (x < minX) minX = x;
          if (x > maxX) maxX = x;
          if (y < minY) minY = y;
          if (y > maxY) maxY = y;
        }
      }
    }
    if (maxX < 0) {
      setMessage(EMPTY_LABEL);
      return;
    }
    const dpr = window.devicePixelRatio || 1;
    const edge = Math.round(6 * dpr);
    minX = Math.max(0, minX - edge);
    minY = Math.max(0, minY - edge);
    maxX = Math.min(canvas.width - 1, maxX + edge);
    maxY = Math.min(canvas.height - 1, maxY + edge);
    const sw = maxX - minX + 1;
    const sh = maxY - minY + 1;
    // 잰 바운딩 박스를 퍼센트로 바꿔 크롭 테두리를 그 자리로 조인다 — 무엇이 잘렸는지 눈에 보인다
    setCropInset(
      `${(minY / canvas.height * 100).toFixed(1)}% ${((canvas.width - maxX - 1) / canvas.width * 100).toFixed(1)}% ` +
      `${((canvas.height - maxY - 1) / canvas.height * 100).toFixed(1)}% ${(minX / canvas.width * 100).toFixed(1)}%`
    );
    const cropped = document.createElement("canvas");
    cropped.width = sw;
    cropped.height = sh;
    const cropCtx = cropped.getContext("2d");
    if (!cropCtx) return;
    // 배경을 칠하지 않고 잘린 자리만 옮기므로 알파가 그대로 남는다 — 투명 배경 PNG 가 된다
    cropCtx.drawImage(canvas, minX, minY, sw, sh, 0, 0, sw, sh);
    // 데모는 iframe 안에서 도니 <a download> 는 동작하지 않는다. 결과는 미리보기 <img> 까지만 보여 준다
    setSrc(cropped.toDataURL("image/png"));
    setMessage(
      TRIM_LABEL
        .replace("%w", String(Math.round((canvas.width - sw) / dpr)))
        .replace("%h", String(Math.round((canvas.height - sh) / dpr)))
    );
  }

  function toLocal(event: ReactPointerEvent<HTMLDivElement>): Point | null {
    const canvas = inkRef.current;
    if (!canvas) return null;
    const r = canvas.getBoundingClientRect();
    return [event.clientX - r.left, event.clientY - r.top];
  }

  function onPointerDown(event: ReactPointerEvent<HTMLDivElement>): void {
    setDemo(false);
    setCropInset("");
    const point = toLocal(event);
    const pad = padRef.current;
    if (!point || !pad) return;
    currentRef.current = [point];
    strokesRef.current.push(currentRef.current);
    pad.setPointerCapture(event.pointerId);
  }

  function onPointerMove(event: ReactPointerEvent<HTMLDivElement>): void {
    const current = currentRef.current;
    if (!current) return;
    const point = toLocal(event);
    if (!point) return;
    current.push(point);
    repaint();
  }

  const cls = [styles.root, demo ? styles.isDemo : "", src ? styles.hasOut : ""].filter(Boolean).join(" ");
  return (
    <main className={styles.stage}>
      <div className={cls} style={vars}>
        <div className={styles.card}>
          <div className={styles.bar}>
            <p className={styles.label}>
              <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor" className={styles.ico} aria-hidden="true"><path d="M67.41,142.56C35.71,129.52,45.41,32.07,78,32,111.82,32.05,92,90.26,67.41,142.56Z" opacity="0.2"/><path d="M232,168H63.86c2.66-5.24,5.33-10.63,8-16.11,14.94,1.65,32.58-8.78,52.66-31.14,5,13.46,14.45,30.93,30.58,31.25,9.09.18,18.11-5.2,27.42-16.37C189.31,143.75,203.3,152,232,152a8,8,0,0,0,0-16c-30.43,0-39.43-10.45-40-16.11a7.67,7.67,0,0,0-5.46-7.75,8.14,8.14,0,0,0-9.25,3.49C165.23,134.17,158,136.06,155.38,136c-8.26-.16-16.66-19.52-19.54-33.42a8,8,0,0,0-14.09-3.37C101.54,124.55,88,133.08,79.57,135.29,88.06,116.42,94.4,99.85,98.46,85.9c6.82-23.44,7.32-39.83,1.51-50.1-3-5.38-9.34-11.8-22.06-11.8C61.85,24,49.18,39.18,43.14,65.65c-3.59,15.71-4.18,33.21-1.62,48s7.87,25.55,15.59,31.94c-3.73,7.72-7.53,15.26-11.23,22.41H24a8,8,0,0,0,0,16H37.41c-11.32,21-20.12,35.64-20.26,35.88a8,8,0,1,0,13.71,8.24c.15-.26,11.27-18.79,24.7-44.12H232a8,8,0,0,0,0-16ZM58.74,69.21C62.72,51.74,70.43,40,77.91,40c5.33,0,7.1,1.86,8.13,3.67,3,5.33,6.52,24.19-21.66,86.39C56.12,118.78,53.31,93,58.74,69.21Z"/></svg>
              <span>서명 내보내기</span>
            </p>
            <button type="button" className={styles.btn} onClick={exportCrop}>
              <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" fill="currentColor" className={styles.ico} aria-hidden="true"><path d="M216,48V208H40V48A16,16,0,0,1,56,32H200A16,16,0,0,1,216,48Z" opacity="0.2"/><path d="M224,144v64a8,8,0,0,1-8,8H40a8,8,0,0,1-8-8V144a8,8,0,0,1,16,0v56H208V144a8,8,0,0,1,16,0Zm-101.66,5.66a8,8,0,0,0,11.32,0l40-40a8,8,0,0,0-11.32-11.32L136,124.69V32a8,8,0,0,0-16,0v92.69L93.66,98.34a8,8,0,0,0-11.32,11.32Z"/></svg>
              <span>PNG 로 내보내기</span>
            </button>
          </div>
          <div className={styles.body}>
            <div className={styles.pad} ref={padRef} onPointerDown={onPointerDown} onPointerMove={onPointerMove}>
              <canvas className={styles.ink} ref={inkRef} role="img" aria-label="서명 칸"></canvas>
              {/* 미리보기용 서명 — canvas 에 그려지는 SAMPLE 과 같은 좌표를 중점 2차 곡선으로 옮긴 것 */}
              <svg className={styles.ghost} viewBox="0 0 200 100" preserveAspectRatio="none" aria-hidden="true">
                <path className={styles.stroke} d="M30,56 Q30,56 33,46 Q36,36 41,31 Q46,26 50,31 Q54,36 52,44 Q50,52 47,56 Q44,60 48,59 Q52,58 59,52 Q66,46 72,39 Q78,32 82,30 Q86,28 88,34 Q90,40 93,46 Q96,52 100,53"/>
                <path className={styles.stroke} d="M112,50 Q112,50 117,42 Q122,34 127,30 Q132,26 136,29 Q140,32 138,39 Q136,46 140,47 Q144,48 150,43 Q156,38 160,33"/>
                <path className={styles.stroke} d="M36,70 Q36,70 53,72 Q70,74 90,75 Q110,76 130,74 Q150,72 161,68"/>
              </svg>
              <span className={styles.crop} style={{ inset: cropInset }} aria-hidden="true"></span>
            </div>
            <div className={styles.out}>
              <span className={styles.outLabel}>미리보기</span>
              <div className={styles.frame}>
                <span className={styles.hint}>결과가 여기 보입니다</span>
                {src ? <img className={styles.img} src={src} alt="여백을 잘라낸 서명 미리보기"/> : null}
                {/* 미리보기 루프에서만 보이는 결과 사본 — viewBox 가 잉크 바깥선이라 잘린 그림이 된다 */}
                <svg className={styles.thumb} viewBox="21 19 149 65" aria-hidden="true">
                  <path className={styles.stroke} d="M30,56 Q30,56 33,46 Q36,36 41,31 Q46,26 50,31 Q54,36 52,44 Q50,52 47,56 Q44,60 48,59 Q52,58 59,52 Q66,46 72,39 Q78,32 82,30 Q86,28 88,34 Q90,40 93,46 Q96,52 100,53"/>
                  <path className={styles.stroke} d="M112,50 Q112,50 117,42 Q122,34 127,30 Q132,26 136,29 Q140,32 138,39 Q136,46 140,47 Q144,48 150,43 Q156,38 160,33"/>
                  <path className={styles.stroke} d="M36,70 Q36,70 53,72 Q70,74 90,75 Q110,76 130,74 Q150,72 161,68"/>
                </svg>
              </div>
            </div>
          </div>
          <p className={styles.live}>
            <span className={styles.liveReal} aria-live="polite">{message}</span>
            <span className={`${styles.liveDemo} ${styles.sayBefore}`} aria-hidden="true">내보내기를 누르면 바깥 여백을 잘라냅니다</span>
            <span className={`${styles.liveDemo} ${styles.sayAfter}`} aria-hidden="true">바깥 여백을 잘라낸 미리보기입니다</span>
          </p>
        </div>
      </div>
    </main>
  );
}