06Lightbox That Closes With a Downward Fling

<main class="stage">
<div class="scene is-demo" id="scene">
  <ul class="grid" id="grid">
    <li><button class="thumb" id="thumb0" type="button" aria-haspopup="dialog"><span class="thumbImg"></span></button></li>
  </ul>
  <div class="backdrop" id="backdrop"></div>
  <div class="lightbox" id="lightbox" role="dialog" aria-modal="true" aria-hidden="true" aria-label="Fling photo to close">
    <span class="fullImg" id="fullImg"></span>
    <p class="dragNote" id="dragNote">Drag down to close</p>
    <button class="closeBtn" id="closeBtn" type="button">Close</button>
  </div>
</div>
</main>

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

// 변수 3개
$duration: $dur-base;
$easing: $ease-spring;
$color: $subject-orange-deep;

// 계산 겹: index.html 의 pointermove 가 매 이동마다 세로 속도(px/ms) 를 재고, pointerup 에서
// 그 속도 또는 드래그 거리 비율로 "던졌는지" 판정한다. 던지면 그 속도로 남은 거리를 마저 날아가는
// 시간을 역산하고(flingClose), 아니면 스프링 오버슛 이징으로 되돌아온다(springBack).
@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%);
}

.grid {
  position: absolute;
  inset: 0;
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: center;
}

.thumb {
  appearance: none;
  border: none;
  background: none;
  padding: 0;
  cursor: pointer;

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

.thumbImg {
  display: block;
  width: 72px;
  height: 72px;
  border-radius: $r-sm;
  box-shadow: $shadow-press;
  background: linear-gradient(135deg, $subject-pink, $subject-lilac);
}

.backdrop {
  position: absolute;
  inset: 0;
  background: $subject-ink;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.lightbox {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  visibility: hidden;
  overflow: hidden;
}

.fullImg {
  display: block;
  width: 190px;
  height: 130px;
  border-radius: $r-card;
  background: linear-gradient(135deg, $subject-pink, $subject-lilac 60%, $subject-sky);
  touch-action: none;
  cursor: grab;

  &:active { cursor: grabbing; }
}

.dragNote {
  position: absolute;
  bottom: $sp-3;
  left: 50%;
  transform: translateX(-50%);
  margin: 0;
  font-size: 10px;
  font-weight: 700;
  color: $subject-cream;
  background: rgba(#000, .38);
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  pointer-events: none;
}

.closeBtn {
  position: absolute;
  top: $sp-2;
  right: $sp-2;
  appearance: none;
  border: none;
  border-radius: $r-pill;
  padding: $sp-1 $sp-3;
  font-size: 11px;
  font-weight: 600;
  color: $subject-ink;
  background: rgba($subject-cream, .92);
  cursor: pointer;

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

@media (max-width: 340px) {
  .scene { width: 220px; height: 124px; }
  .fullImg { width: 140px; height: 96px; }
}

@media (prefers-reduced-motion: reduce) {
  // 실사용 경로 적용 — 던지기·스프링백 트윈은 index.html 의 animate() 가 reduce 시 즉시 최종 상태로 처리한다.
  .closeBtn, .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: #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%);
}

.grid {
  position: absolute;
  inset: 0;
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: center;
}

.thumb {
  appearance: none;
  border: none;
  background: none;
  padding: 0;
  cursor: pointer;
}
.thumb:focus-visible .thumbImg {
  outline: 2px solid #c93000;
  outline-offset: 2px;
}

.thumbImg {
  display: block;
  width: 72px;
  height: 72px;
  border-radius: 8px;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  background: linear-gradient(135deg, #ff9ebb, #b9a0ff);
}

.backdrop {
  position: absolute;
  inset: 0;
  background: #17141a;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}

.lightbox {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  visibility: hidden;
  overflow: hidden;
}

.fullImg {
  display: block;
  width: 190px;
  height: 130px;
  border-radius: 16px;
  background: linear-gradient(135deg, #ff9ebb, #b9a0ff 60%, #6ec8ff);
  touch-action: none;
  cursor: grab;
}
.fullImg:active {
  cursor: grabbing;
}

.dragNote {
  position: absolute;
  bottom: 12px;
  left: 50%;
  transform: translateX(-50%);
  margin: 0;
  font-size: 10px;
  font-weight: 700;
  color: #fff7e6;
  background: rgba(0, 0, 0, 0.38);
  padding: 4px 12px;
  border-radius: 999px;
  pointer-events: none;
}

.closeBtn {
  position: absolute;
  top: 8px;
  right: 8px;
  appearance: none;
  border: none;
  border-radius: 999px;
  padding: 4px 12px;
  font-size: 11px;
  font-weight: 600;
  color: #17141a;
  background: rgba(255, 247, 230, 0.92);
  cursor: pointer;
}
.closeBtn:focus-visible {
  outline: 2px solid #c93000;
  outline-offset: 2px;
}

@media (max-width: 340px) {
  .scene {
    width: 220px;
    height: 124px;
  }
  .fullImg {
    width: 140px;
    height: 96px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .closeBtn, .thumb {
    transition: none;
  }
}

(function () {
  var LIGHTBOX_FLING_VELOCITY_PX_MS = 0.5; // 놓는 순간 이 속도(px/ms) 를 넘으면 던진 것으로 본다
  var DRAG_COMMIT_RATIO = 0.32; // 드래그 거리 / 무대 높이 가 이 비율을 넘어도 던진 것으로 본다
  var SPRING_BACK_MS = 380;
  var LOOP_MS = 2000;

  var scene = document.getElementById('scene');
  var backdrop = document.getElementById('backdrop');
  var lightbox = document.getElementById('lightbox');
  var fullImg = document.getElementById('fullImg');
  var dragNote = document.getElementById('dragNote');
  var closeBtn = document.getElementById('closeBtn');
  var thumb = document.getElementById('thumb0');
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var open = false;
  var dragging = false;
  var dragStartY = 0;
  var dragStartX = 0;
  var curY = 0;
  var curX = 0;
  var lastMoveY = 0;
  var lastMoveT = 0;
  var velocityY = 0;
  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); }
  // 스프링 오버슛: 목표를 살짝 지나쳤다 되돌아온다
  function easeSpringBack(t) { var p = t - 1; return 1 + p * p * (2.7 * p + 1.7); }
  function stageH() { return scene.getBoundingClientRect().height; }

  function animate(duration, onFrame, onDone, easeFn) {
    var ease = easeFn || easeOutCubic;
    if (reduce) { onFrame(1); if (onDone) onDone(); return; }
    var start = performance.now();
    function frame(now) {
      var p = clamp((now - start) / duration, 0, 1);
      onFrame(ease(p));
      if (p < 1) requestAnimationFrame(frame);
      else if (onDone) onDone();
    }
    requestAnimationFrame(frame);
  }

  function setDrag(x, y, progress) {
    fullImg.style.transform = 'translate(' + x.toFixed(2) + 'px,' + y.toFixed(2) + 'px) scale(' + (1 - progress * 0.22).toFixed(4) + ')';
    backdrop.style.opacity = (0.78 * (1 - progress)).toFixed(3);
    dragNote.style.opacity = (1 - progress * 2).toFixed(3);
  }

  function openFrom() {
    if (open) return;
    open = true;
    curX = 0; curY = 0;
    dragNote.style.opacity = '1';
    setDrag(0, 0, 0);
    lightbox.style.visibility = 'visible';
    lightbox.setAttribute('aria-hidden', 'false');
    backdrop.style.visibility = 'visible';
    animate(240, function (e) { backdrop.style.opacity = (e * 0.78).toFixed(3); }, function () {
      closeBtn.focus({ preventScroll: true });
    });
  }

  function closeLightbox() {
    if (!open) return;
    lightbox.style.visibility = 'hidden';
    lightbox.setAttribute('aria-hidden', 'true');
    backdrop.style.visibility = 'hidden';
    open = false;
    thumb.focus({ preventScroll: true });
  }

  // 던진 속도로 남은 거리를 마저 날아가게 한다 — 값이 클수록 짧고 빠르게 끝난다
  function flingClose(vy) {
    var h = stageH();
    var fromY = curY;
    var fromX = curX;
    var targetY = fromY + Math.sign(vy || 1) * (h * 1.4);
    var duration = clamp(220 / Math.max(Math.abs(vy), 0.35), 120, 320);
    animate(duration, function (e) {
      var y = fromY + (targetY - fromY) * e;
      var progress = clamp(Math.abs(y) / h, 0, 1);
      setDrag(fromX * (1 - e), y, progress);
    }, closeLightbox, function (t) { return t; });
  }

  function springBack() {
    var fromX = curX;
    var fromY = curY;
    animate(SPRING_BACK_MS, function (e) {
      setDrag(fromX * (1 - e), fromY * (1 - e), 0);
    }, function () {
      curX = 0; curY = 0;
      closeBtn.focus({ preventScroll: true });
    }, easeSpringBack);
  }

  function human() {
    if (scene.classList.contains('is-demo')) {
      scene.classList.remove('is-demo');
      timers.forEach(function (id) { clearTimeout(id); clearInterval(id); });
      timers = [];
    }
  }

  thumb.addEventListener('click', function () { human(); openFrom(); });
  closeBtn.addEventListener('click', function () { human(); closeLightbox(); });
  backdrop.addEventListener('click', function () { human(); closeLightbox(); });
  document.addEventListener('keydown', function (e) {
    if (open && e.key === 'Escape') { human(); closeLightbox(); }
  });

  fullImg.addEventListener('pointerdown', function (e) {
    human();
    dragging = true;
    dragStartX = e.clientX;
    dragStartY = e.clientY;
    lastMoveY = e.clientY;
    lastMoveT = performance.now();
    velocityY = 0;
    fullImg.setPointerCapture(e.pointerId);
  });
  fullImg.addEventListener('pointermove', function (e) {
    if (!dragging) return;
    var now = performance.now();
    var dt = now - lastMoveT;
    if (dt > 0) velocityY = (e.clientY - lastMoveY) / dt;
    lastMoveY = e.clientY;
    lastMoveT = now;
    curX = e.clientX - dragStartX;
    curY = Math.max(0, e.clientY - dragStartY);
    var progress = clamp(curY / (stageH() * DRAG_COMMIT_RATIO), 0, 1);
    setDrag(curX, curY, progress);
  });
  function endDrag() {
    if (!dragging) return;
    dragging = false;
    var h = stageH();
    var commit = curY > h * DRAG_COMMIT_RATIO || Math.abs(velocityY) > LIGHTBOX_FLING_VELOCITY_PX_MS;
    if (commit) flingClose(velocityY);
    else springBack();
  }
  fullImg.addEventListener('pointerup', endDrag);
  fullImg.addEventListener('pointercancel', endDrag);

  function cycle() {
    openFrom();
    timers.push(setTimeout(function () {
      curX = 6; curY = 0;
      var h = stageH();
      var fromY = 0;
      animate(360, function (e) {
        curY = fromY + h * 0.62 * e;
        setDrag(curX * (1 - e * 0.4), curY, e * 0.7);
      }, function () {
        flingClose(LIGHTBOX_FLING_VELOCITY_PX_MS * 1.6);
      });
    }, 420));
  }

  if (!reduce) {
    cycle();
    timers.push(setInterval(function () {
      if (scene.classList.contains('is-demo')) cycle();
    }, LOOP_MS));
  }
})();

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

const LIGHTBOX_FLING_VELOCITY_PX_MS = 0.5; // 놓는 순간 이 속도(px/ms) 를 넘으면 던진 것으로 본다
const DRAG_COMMIT_RATIO = 0.32; // 드래그 거리 / 무대 높이 가 이 비율을 넘어도 던진 것으로 본다
const SPRING_BACK_MS = 380;
const LOOP_MS = 2000;

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

  useEffect(() => {
    const scene0 = sceneRef.current;
    if (!scene0) return undefined;
    const backdrop0 = scene0.querySelector<HTMLDivElement>('.' + styles.backdrop);
    const lightbox0 = scene0.querySelector<HTMLDivElement>('.' + styles.lightbox);
    const fullImg0 = scene0.querySelector<HTMLSpanElement>('.' + styles.fullImg);
    const dragNote0 = scene0.querySelector<HTMLParagraphElement>('.' + styles.dragNote);
    const closeBtn0 = scene0.querySelector<HTMLButtonElement>('.' + styles.closeBtn);
    const thumb0 = scene0.querySelector<HTMLButtonElement>('.' + styles.thumb);
    if (!backdrop0 || !lightbox0 || !fullImg0 || !dragNote0 || !closeBtn0 || !thumb0) return undefined;
    const scene = scene0;
    const backdrop = backdrop0;
    const lightbox = lightbox0;
    const fullImg = fullImg0;
    const dragNote = dragNote0;
    const closeBtn = closeBtn0;
    const thumb = thumb0;

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

    let open = false;
    let dragging = false;
    let dragStartY = 0;
    let dragStartX = 0;
    let curY = 0;
    let curX = 0;
    let lastMoveY = 0;
    let lastMoveT = 0;
    let velocityY = 0;
    let timers: 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); }
    // 스프링 오버슛: 목표를 살짝 지나쳤다 되돌아온다
    function easeSpringBack(t: number) { const p = t - 1; return 1 + p * p * (2.7 * p + 1.7); }
    function stageH() { return scene.getBoundingClientRect().height; }

    function animate(duration: number, onFrame: (e: number) => void, onDone?: () => void, easeFn?: (t: number) => number) {
      const ease = easeFn || easeOutCubic;
      if (reduce) { onFrame(1); if (onDone) onDone(); return; }
      const start = performance.now();
      function frame(now: number) {
        const p = clamp((now - start) / duration, 0, 1);
        onFrame(ease(p));
        if (p < 1) requestAnimationFrame(frame);
        else if (onDone) onDone();
      }
      requestAnimationFrame(frame);
    }

    function setDrag(x: number, y: number, progress: number) {
      fullImg.style.transform = 'translate(' + x.toFixed(2) + 'px,' + y.toFixed(2) + 'px) scale(' + (1 - progress * 0.22).toFixed(4) + ')';
      backdrop.style.opacity = (0.78 * (1 - progress)).toFixed(3);
      dragNote.style.opacity = (1 - progress * 2).toFixed(3);
    }

    function openFrom() {
      if (open) return;
      open = true;
      curX = 0; curY = 0;
      dragNote.style.opacity = '1';
      setDrag(0, 0, 0);
      lightbox.style.visibility = 'visible';
      lightbox.setAttribute('aria-hidden', 'false');
      backdrop.style.visibility = 'visible';
      animate(240, (e) => { backdrop.style.opacity = (e * 0.78).toFixed(3); }, () => {
        closeBtn.focus({ preventScroll: true });
      });
    }

    function closeLightbox() {
      if (!open) return;
      lightbox.style.visibility = 'hidden';
      lightbox.setAttribute('aria-hidden', 'true');
      backdrop.style.visibility = 'hidden';
      open = false;
      thumb.focus({ preventScroll: true });
    }

    // 던진 속도로 남은 거리를 마저 날아가게 한다 — 값이 클수록 짧고 빠르게 끝난다
    function flingClose(vy: number) {
      const h = stageH();
      const fromY = curY;
      const fromX = curX;
      const targetY = fromY + Math.sign(vy || 1) * (h * 1.4);
      const duration = clamp(220 / Math.max(Math.abs(vy), 0.35), 120, 320);
      animate(duration, (e) => {
        const y = fromY + (targetY - fromY) * e;
        const progress = clamp(Math.abs(y) / h, 0, 1);
        setDrag(fromX * (1 - e), y, progress);
      }, closeLightbox, (t) => t);
    }

    function springBack() {
      const fromX = curX;
      const fromY = curY;
      animate(SPRING_BACK_MS, (e) => {
        setDrag(fromX * (1 - e), fromY * (1 - e), 0);
      }, () => {
        curX = 0; curY = 0;
        closeBtn.focus({ preventScroll: true });
      }, easeSpringBack);
    }

    function human() {
      if (scene.classList.contains(styles['is-demo'])) {
        scene.classList.remove(styles['is-demo']);
        timers.forEach((id) => { window.clearTimeout(id); window.clearInterval(id); });
        timers = [];
      }
    }

    function onThumbClick() { human(); openFrom(); }
    function onCloseClick() { human(); closeLightbox(); }
    function onBackdropClick() { human(); closeLightbox(); }
    function onKeydown(e: KeyboardEvent) {
      if (open && e.key === 'Escape') { human(); closeLightbox(); }
    }
    thumb.addEventListener('click', onThumbClick);
    closeBtn.addEventListener('click', onCloseClick);
    backdrop.addEventListener('click', onBackdropClick);
    document.addEventListener('keydown', onKeydown);

    function onPointerDown(e: PointerEvent) {
      human();
      dragging = true;
      dragStartX = e.clientX;
      dragStartY = e.clientY;
      lastMoveY = e.clientY;
      lastMoveT = performance.now();
      velocityY = 0;
      fullImg.setPointerCapture(e.pointerId);
    }
    function onPointerMove(e: PointerEvent) {
      if (!dragging) return;
      const now = performance.now();
      const dt = now - lastMoveT;
      if (dt > 0) velocityY = (e.clientY - lastMoveY) / dt;
      lastMoveY = e.clientY;
      lastMoveT = now;
      curX = e.clientX - dragStartX;
      curY = Math.max(0, e.clientY - dragStartY);
      const progress = clamp(curY / (stageH() * DRAG_COMMIT_RATIO), 0, 1);
      setDrag(curX, curY, progress);
    }
    function endDrag() {
      if (!dragging) return;
      dragging = false;
      const h = stageH();
      const commit = curY > h * DRAG_COMMIT_RATIO || Math.abs(velocityY) > LIGHTBOX_FLING_VELOCITY_PX_MS;
      if (commit) flingClose(velocityY);
      else springBack();
    }
    fullImg.addEventListener('pointerdown', onPointerDown);
    fullImg.addEventListener('pointermove', onPointerMove);
    fullImg.addEventListener('pointerup', endDrag);
    fullImg.addEventListener('pointercancel', endDrag);

    function cycle() {
      openFrom();
      timers.push(window.setTimeout(() => {
        curX = 6; curY = 0;
        const h = stageH();
        const fromY = 0;
        animate(360, (e) => {
          curY = fromY + h * 0.62 * e;
          setDrag(curX * (1 - e * 0.4), curY, e * 0.7);
        }, () => {
          flingClose(LIGHTBOX_FLING_VELOCITY_PX_MS * 1.6);
        });
      }, 420));
    }

    if (!reduce) {
      cycle();
      timers.push(window.setInterval(() => {
        if (scene.classList.contains(styles['is-demo'])) cycle();
      }, LOOP_MS));
    }

    return () => {
      timers.forEach((id) => { window.clearTimeout(id); window.clearInterval(id); });
      thumb.removeEventListener('click', onThumbClick);
      closeBtn.removeEventListener('click', onCloseClick);
      backdrop.removeEventListener('click', onBackdropClick);
      document.removeEventListener('keydown', onKeydown);
      fullImg.removeEventListener('pointerdown', onPointerDown);
      fullImg.removeEventListener('pointermove', onPointerMove);
      fullImg.removeEventListener('pointerup', endDrag);
      fullImg.removeEventListener('pointercancel', endDrag);
    };
  }, []);

  return (
    <div className={`${styles.scene} ${styles['is-demo']}`} ref={sceneRef}>
      <ul className={styles.grid}>
        <li><button className={styles.thumb} type="button" aria-haspopup="dialog"><span className={styles.thumbImg} /></button></li>
      </ul>
      <div className={styles.backdrop} />
      <div className={styles.lightbox} role="dialog" aria-modal="true" aria-hidden="true" aria-label="사진 던져서 닫기">
        <span className={styles.fullImg} />
        <p className={styles.dragNote}>아래로 끌어서 닫기</p>
        <button className={styles.closeBtn} type="button">닫기</button>
      </div>
    </div>
  );
}