02Aspect-Locked Resize From Four Corner Handles

<main class="stage">
<div class="scene is-demo" id="scene">
  <div class="frame" id="frame" tabindex="0" aria-label="Resize frame — drag a corner handle to scale up or down while keeping the aspect ratio">
    <div class="subjectShape"></div>
    <div class="handle handle--tl" data-corner="tl" tabindex="0" role="slider" aria-label="Top-left corner handle" aria-valuemin="50" aria-valuemax="180" aria-valuenow="100"></div>
    <div class="handle handle--tr" data-corner="tr" tabindex="0" role="slider" aria-label="Top-right corner handle" aria-valuemin="50" aria-valuemax="180" aria-valuenow="100"></div>
    <div class="handle handle--bl" data-corner="bl" tabindex="0" role="slider" aria-label="Bottom-left corner handle" aria-valuemin="50" aria-valuemax="180" aria-valuenow="100"></div>
    <div class="handle handle--br" data-corner="br" tabindex="0" role="slider" aria-label="Bottom-right corner handle" aria-valuemin="50" aria-valuemax="180" aria-valuenow="100"></div>
  </div>
  <div class="readout" id="readout" aria-hidden="true"><span id="rp">100</span>%</div>
</div>
</main>

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

// 변수 3개
$duration: $dur-enter;
$easing: $ease-out;
$color: $subject-sky;

// 계산 겹: index.html 의 applyScale() 이 앵커(대각선 반대 모서리)→포인터 거리비로 균일 scale() 을
// 만들고 transform-origin 을 앵커 좌표에 둔다 — 앵커는 어떤 배율에서도 화면에서 움직이지 않는다.
@include stage($stage-yellow);

.scene {
  position: relative;
  width: 320px;
  height: 180px;
  border-radius: $r-card;
  overflow: hidden;
  box-shadow: $shadow-raised;
  background: linear-gradient(160deg, #fff3c4, $stage-yellow 85%);
}

.frame {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 110px;
  height: 72px;
  margin-top: -36px;
  margin-left: -55px;

  &:focus-visible { outline: 2px solid $color; outline-offset: 6px; }
}

.subjectShape {
  width: 100%;
  height: 100%;
  border-radius: $r-sm;
  background: linear-gradient(135deg, $subject-mint, $subject-sky);
  box-shadow: $shadow-press;
  will-change: transform;
}

.handle {
  position: absolute;
  width: 14px;
  height: 14px;
  margin: -7px;
  border-radius: $r-xs;
  background: $subject-ink;
  border: 2px solid $subject-cream;
  cursor: nwse-resize;
  touch-action: none;

  &--tl { top: 0; left: 0; }
  &--tr { top: 0; left: 100%; cursor: nesw-resize; }
  &--bl { top: 100%; left: 0; cursor: nesw-resize; }
  &--br { top: 100%; left: 100%; }

  &.isActive, &:focus-visible { background: $color; }
}

.readout {
  position: absolute;
  left: $sp-3;
  bottom: $sp-3;
  padding: $sp-1 $sp-2;
  border-radius: $r-pill;
  background: rgba($subject-ink, .78);
  color: $subject-cream;
  font-size: 10px;
  font-variant-numeric: tabular-nums;
}

@media (max-width: 340px) {
  .scene { width: 220px; height: 124px; }
  .frame { width: 78px; height: 52px; margin-top: -26px; margin-left: -39px; }
  .handle { width: 12px; height: 12px; margin: -6px; }
  .readout { font-size: 9px; }
}

@media (prefers-reduced-motion: reduce) {
  // 실사용 경로 적용 — 핸들 드래그·키보드는 index.html 이 트윈 없이 즉시 반영한다.
  // scss 만: 핸들 색 전환만 꺼서 잔여 트랜지션을 없앤다.
  .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: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.scene {
  position: relative;
  width: 320px;
  height: 180px;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  background: linear-gradient(160deg, #fff3c4, #ffd23f 85%);
}

.frame {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 110px;
  height: 72px;
  margin-top: -36px;
  margin-left: -55px;
}
.frame:focus-visible {
  outline: 2px solid #6ec8ff;
  outline-offset: 6px;
}

.subjectShape {
  width: 100%;
  height: 100%;
  border-radius: 8px;
  background: linear-gradient(135deg, #4cd4a6, #6ec8ff);
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  will-change: transform;
}

.handle {
  position: absolute;
  width: 14px;
  height: 14px;
  margin: -7px;
  border-radius: 4px;
  background: #17141a;
  border: 2px solid #fff7e6;
  cursor: nwse-resize;
  touch-action: none;
}
.handle--tl {
  top: 0;
  left: 0;
}
.handle--tr {
  top: 0;
  left: 100%;
  cursor: nesw-resize;
}
.handle--bl {
  top: 100%;
  left: 0;
  cursor: nesw-resize;
}
.handle--br {
  top: 100%;
  left: 100%;
}
.handle.isActive, .handle:focus-visible {
  background: #6ec8ff;
}

.readout {
  position: absolute;
  left: 12px;
  bottom: 12px;
  padding: 4px 8px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.78);
  color: #fff7e6;
  font-size: 10px;
  font-variant-numeric: tabular-nums;
}

@media (max-width: 340px) {
  .scene {
    width: 220px;
    height: 124px;
  }
  .frame {
    width: 78px;
    height: 52px;
    margin-top: -26px;
    margin-left: -39px;
  }
  .handle {
    width: 12px;
    height: 12px;
    margin: -6px;
  }
  .readout {
    font-size: 9px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .handle {
    transition: none;
  }
}

(function () {
  var MIN_SCALE = 0.55;
  var MAX_SCALE = 1.75;
  var LOOP_SEQUENCE = [1.5, 0.7, 1];
  var HOP_MS = 620;
  var HOLD_MS = 340;

  var scene = document.getElementById('scene');
  var frame = document.getElementById('frame');
  var subject = frame.querySelector('.subjectShape');
  var handles = [].slice.call(frame.querySelectorAll('.handle'));
  var rp = document.getElementById('rp');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  // 앵커 고정 비율 산술: 드래그하는 모서리의 대각선 반대쪽을 앵커로 고정하고, 앵커→포인터 거리의
  // 비로 균일 스케일을 만든다. transform-origin 을 앵커 좌표에 두면 그 점은 화면에서 움직이지 않는다.
  var ORIGIN_BY_CORNER = {
    tl: '100% 100%',
    tr: '0% 100%',
    bl: '100% 0%',
    br: '0% 0%'
  };

  var scale = 1;
  var dragCorner = null;
  var anchorX = 0, anchorY = 0, d0 = 1, s0 = 1;
  var timers = [];

  function clamp(v, lo, hi) { return Math.min(hi, Math.max(lo, v)); }
  function easeOutCubic(t) { return 1 - Math.pow(1 - t, 3); }
  function dist(x1, y1, x2, y2) { return Math.hypot(x2 - x1, y2 - y1); }

  function applyScale(corner, s) {
    scale = clamp(s, MIN_SCALE, MAX_SCALE);
    subject.style.transformOrigin = ORIGIN_BY_CORNER[corner];
    subject.style.transform = 'scale(' + scale.toFixed(3) + ')';
    rp.textContent = Math.round(scale * 100);
    handles.forEach(function (h) { h.setAttribute('aria-valuenow', String(Math.round(scale * 100))); });
  }

  function human() {
    if (scene.classList.contains('is-demo')) {
      scene.classList.remove('is-demo');
      timers.forEach(function (t) { clearTimeout(t); clearInterval(t); });
      timers = [];
    }
  }

  function cornerAnchorRect(corner) {
    var r = frame.getBoundingClientRect();
    switch (corner) {
      case 'tl': return { x: r.right, y: r.bottom };
      case 'tr': return { x: r.left, y: r.bottom };
      case 'bl': return { x: r.right, y: r.top };
      default: return { x: r.left, y: r.top };
    }
  }

  handles.forEach(function (h) {
    h.addEventListener('pointerdown', function (e) {
      human();
      dragCorner = h.dataset.corner;
      h.setPointerCapture(e.pointerId);
      var a = cornerAnchorRect(dragCorner);
      anchorX = a.x; anchorY = a.y;
      d0 = Math.max(1, dist(anchorX, anchorY, e.clientX, e.clientY));
      s0 = scale;
      h.classList.add('isActive');
    });
    h.addEventListener('pointermove', function (e) {
      if (dragCorner !== h.dataset.corner) return;
      var d1 = dist(anchorX, anchorY, e.clientX, e.clientY);
      applyScale(dragCorner, s0 * (d1 / d0));
    });
    function end(e) {
      if (dragCorner !== h.dataset.corner) return;
      dragCorner = null;
      h.classList.remove('isActive');
      try { h.releasePointerCapture(e.pointerId); } catch (err) {}
    }
    h.addEventListener('pointerup', end);
    h.addEventListener('pointercancel', end);
    h.addEventListener('keydown', function (e) {
      var corner = h.dataset.corner;
      if (e.key === 'ArrowUp' || e.key === 'ArrowRight') { human(); applyScale(corner, scale + 0.08); e.preventDefault(); }
      else if (e.key === 'ArrowDown' || e.key === 'ArrowLeft') { human(); applyScale(corner, scale - 0.08); e.preventDefault(); }
    });
  });

  // reduce: 실사용 경로 적용 — 핸들 pointer·keydown 은 위에서 트윈 없이 즉시 반영한다.
  // 아래 hopScale()·cycle() 은 시연 게이트만 — reduce 에서는 돌지 않는다.
  function hopScale(corner, target, onDone) {
    var from = scale;
    var start = performance.now();
    function frame(now) {
      if (!scene.classList.contains('is-demo')) return;
      var p = clamp((now - start) / HOP_MS, 0, 1);
      applyScale(corner, from + (target - from) * easeOutCubic(p));
      if (p < 1) requestAnimationFrame(frame);
      else if (onDone) onDone();
    }
    requestAnimationFrame(frame);
  }

  function cycle(i) {
    if (!scene.classList.contains('is-demo')) return;
    var target = LOOP_SEQUENCE[i % LOOP_SEQUENCE.length];
    hopScale('br', target, function () {
      timers.push(setTimeout(function () { cycle(i + 1); }, HOLD_MS));
    });
  }

  if (!reduce) {
    cycle(0);
  }
})();

import { useEffect, useRef } from 'react';
import styles from './XfCornerScale.module.scss';

const MIN_SCALE = 0.55;
const MAX_SCALE = 1.75;
const KEY_STEP = 0.08;
const HOP_MS = 560;
const HOLD_MS = 340;
const LOOP_SEQUENCE = [1.5, 0.7, 1];
const ORIGIN_BY_CORNER: Record<string, string> = {
  tl: '100% 100%',
  tr: '0% 100%',
  bl: '100% 0%',
  br: '0% 0%'
};

export default function XfCornerScale() {
  const sceneRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    const scene0 = sceneRef.current;
    if (!scene0) return undefined;
    const scene = scene0;
    const frame0 = scene.querySelector<HTMLDivElement>('.' + styles.frame);
    const subject0 = scene.querySelector<HTMLDivElement>('#subject');
    const rp0 = scene.querySelector<HTMLSpanElement>('#rp');
    const handles = Array.from(scene.querySelectorAll<HTMLDivElement>('.' + styles.handle));
    if (!frame0 || !subject0 || !rp0 || handles.length === 0) return undefined;
    const frame = frame0;
    const subject = subject0;
    const rp = rp0;

    const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

    let scale = 1;
    let rafId = 0;
    let timers: number[] = [];
    const dragByCorner: Record<string, boolean> = {};
    const originByCorner: Record<string, { x: number; y: number }> = {};

    function clamp(v: number, lo: number, hi: number) { return Math.min(hi, Math.max(lo, v)); }
    function easeOutCubic(t: number) { return 1 - Math.pow(1 - t, 3); }

    // 앵커 고정 비율 산술: 드래그하는 모서리의 대각선 반대쪽을 앵커로 고정하고(transformOrigin),
    // 앵커→포인터 거리의 비로 균일 스케일을 만든다.
    function cornerAnchorRect(corner: string) {
      const r = frame.getBoundingClientRect();
      const ax = corner === 'tl' || corner === 'bl' ? r.right : r.left;
      const ay = corner === 'tl' || corner === 'tr' ? r.bottom : r.top;
      return { x: ax, y: ay };
    }

    function applyScale(corner: string, s: number) {
      scale = clamp(s, MIN_SCALE, MAX_SCALE);
      subject.style.transformOrigin = ORIGIN_BY_CORNER[corner] || '50% 50%';
      subject.style.transform = 'scale(' + scale.toFixed(3) + ')';
      rp.textContent = String(Math.round(scale * 100));
      handles.forEach((h) => h.setAttribute('aria-valuenow', String(Math.round(scale * 100))));
    }

    function human() {
      if (scene.classList.contains(styles['is-demo'])) {
        scene.classList.remove(styles['is-demo']);
        timers.forEach((t) => window.clearTimeout(t));
        timers = [];
      }
    }

    function bindHandle(handle: HTMLDivElement) {
      const corner = handle.dataset.corner || 'br';
      function onDown(e: PointerEvent) {
        human();
        dragByCorner[corner] = true;
        handle.setPointerCapture(e.pointerId);
        const anchor = cornerAnchorRect(corner);
        originByCorner[corner] = { x: e.clientX - anchor.x, y: e.clientY - anchor.y };
      }
      function onMove(e: PointerEvent) {
        if (!dragByCorner[corner]) return;
        const anchor = cornerAnchorRect(corner);
        const dx = e.clientX - anchor.x;
        const dy = e.clientY - anchor.y;
        const dNow = Math.hypot(dx, dy);
        const d0 = Math.hypot(originByCorner[corner].x, originByCorner[corner].y);
        if (d0 === 0) return;
        applyScale(corner, scale * (dNow / d0));
        originByCorner[corner] = { x: dx, y: dy };
      }
      function onUp(e: PointerEvent) {
        if (!dragByCorner[corner]) return;
        dragByCorner[corner] = false;
        try { handle.releasePointerCapture(e.pointerId); } catch { /* 캡처가 이미 풀린 경우 */ }
      }
      function onKey(e: KeyboardEvent) {
        if (e.key === 'ArrowUp' || e.key === 'ArrowRight') { human(); applyScale(corner, scale + KEY_STEP); e.preventDefault(); }
        else if (e.key === 'ArrowDown' || e.key === 'ArrowLeft') { human(); applyScale(corner, scale - KEY_STEP); e.preventDefault(); }
      }
      handle.addEventListener('pointerdown', onDown);
      handle.addEventListener('pointermove', onMove);
      handle.addEventListener('pointerup', onUp);
      handle.addEventListener('pointercancel', onUp);
      handle.addEventListener('keydown', onKey);
      cleanups.push(() => {
        handle.removeEventListener('pointerdown', onDown);
        handle.removeEventListener('pointermove', onMove);
        handle.removeEventListener('pointerup', onUp);
        handle.removeEventListener('pointercancel', onUp);
        handle.removeEventListener('keydown', onKey);
      });
    }

    const cleanups: Array<() => void> = [];
    handles.forEach(bindHandle);
    applyScale('br', 1);

    // reduce: 실사용 경로 적용 — 핸들 드래그·키보드는 위에서 즉시 반영한다.
    // 아래 자동 루프는 시연 게이트만 — reduce 에서는 돌지 않는다.
    function hopScale(corner: string, target: number, onDone: () => void) {
      const from = scale;
      const start = performance.now();
      function frame(now: number) {
        if (!scene.classList.contains(styles['is-demo'])) return;
        const p = clamp((now - start) / HOP_MS, 0, 1);
        applyScale(corner, from + (target - from) * easeOutCubic(p));
        if (p < 1) rafId = requestAnimationFrame(frame);
        else onDone();
      }
      rafId = requestAnimationFrame(frame);
    }

    function cycle(i: number) {
      if (!scene.classList.contains(styles['is-demo'])) return;
      const target = LOOP_SEQUENCE[i % LOOP_SEQUENCE.length];
      hopScale('br', target, () => {
        timers.push(window.setTimeout(() => cycle(i + 1), HOLD_MS));
      });
    }

    if (!reduce) {
      cycle(0);
    }

    return () => {
      cleanups.forEach((fn) => fn());
      timers.forEach((t) => window.clearTimeout(t));
      cancelAnimationFrame(rafId);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.scene + ' ' + styles['is-demo']} ref={sceneRef}>
        <div className={styles.frame} tabIndex={0} aria-label="크기 조절 프레임, 모서리 핸들을 드래그">
          <div id="subject" className={styles.subjectShape}></div>
          <div className={styles.handle} data-corner="tl" role="slider" tabIndex={0} aria-label="왼쪽 위 모서리 핸들" aria-valuemin={50} aria-valuemax={180} aria-valuenow={100}></div>
          <div className={styles.handle} data-corner="tr" role="slider" tabIndex={0} aria-label="오른쪽 위 모서리 핸들" aria-valuemin={50} aria-valuemax={180} aria-valuenow={100}></div>
          <div className={styles.handle} data-corner="bl" role="slider" tabIndex={0} aria-label="왼쪽 아래 모서리 핸들" aria-valuemin={50} aria-valuemax={180} aria-valuenow={100}></div>
          <div className={styles.handle} data-corner="br" role="slider" tabIndex={0} aria-label="오른쪽 아래 모서리 핸들" aria-valuemin={50} aria-valuemax={180} aria-valuenow={100}></div>
        </div>
        <div className={styles.readout} aria-hidden="true"><span id="rp">100</span>%</div>
      </div>
    </main>
  );
}