06Handle grip feedback

<main class="stage">
  <div class="hg is-demo" id="hg-root">
    <div class="hg__box" id="hg-box">
      <section class="hg__pane hg__pane--l" aria-label="Left pane">
        <span class="hg__ln"></span>
        <span class="hg__ln hg__ln--s"></span>
        <span class="hg__ln"></span>
      </section>
      <div class="hg__bar" id="hg-bar" role="separator" tabindex="0"
           aria-orientation="vertical" aria-label="Split width" aria-valuemin="20" aria-valuemax="80" aria-valuenow="46">
        <i class="hg__hair" aria-hidden="true"></i>
        <i class="hg__dots" aria-hidden="true"><s></s><s></s><s></s></i>
      </div>
      <section class="hg__pane hg__pane--r" aria-label="Right pane">
        <span class="hg__ln hg__ln--d"></span>
        <span class="hg__ln hg__ln--d hg__ln--s"></span>
      </section>
    </div>
    <p class="hg__cap">It widens on hover and stays lit while you drag</p>
  </div>
</main>

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

$duration: $dur-quick;
$easing: cubic-bezier(.2, .8, .2, 1);
$color: $subject-cream;

@include stage($stage-orange);

@property --split {
  syntax: "<percentage>";
  inherits: true;
  initial-value: 46%;
}

.hg {
  --split: 46%;
  width: min(300px, 88vw);
  display: flex;
  flex-direction: column;
  gap: $sp-2;
}
.hg__box {
  display: grid;
  grid-template-columns: var(--split) 20px 1fr;
  height: 120px;
  border-radius: $r-card;
  overflow: hidden;
  background: rgba(23, 20, 26, .2);
}
.hg__pane {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: $sp-2;
  padding: $sp-3;
  overflow: hidden;
}
.hg__ln {
  flex: 0 0 auto;
  height: 8px;
  border-radius: $r-xs;
  background: rgba(23, 20, 26, .2);
}
.hg__ln--d { background: rgba(255, 247, 230, .32); }
.hg__ln--s { width: 58%; }
.hg__pane--l { background: rgba(255, 247, 230, .9); }
.hg__pane--r { background: rgba(23, 20, 26, .78); }

.hg__bar {
  position: relative;
  display: grid;
  place-items: center;
  background: transparent;
  cursor: col-resize;
  touch-action: none;
}
// 평소엔 머리카락 한 줄. 호버·드래그에서 넓어진다
.hg__hair {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 20px;
  border-radius: $r-pill;
  background: $subject-ink;
  transform: translateX(-10px) scaleX(.1);
  transition: transform $duration $easing, background $duration $easing;
}
.hg__dots {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: $sp-1;
  opacity: 0;
  transform: scale(.5);
  transition: opacity $duration $easing, transform $duration $easing;
}
.hg__dots s {
  display: block;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: $color;
}
.hg.is-near .hg__hair,
.hg__bar:hover .hg__hair { transform: translateX(-10px) scaleX(1); }
.hg.is-near .hg__dots,
.hg__bar:hover .hg__dots { opacity: 1; transform: scale(1); }
.hg.is-drag .hg__hair { background: $subject-blue; }
.hg__bar:focus-visible { outline: 2px solid $subject-ink; outline-offset: -2px; }

.hg__cap {
  margin: 0;
  font-size: 11px;
  line-height: 14px;
  font-weight: 700;
  color: $subject-ink;   // AA 4.5: cream on orange 2.76 -> ink 5.50
  text-align: center;
}

// ── 자동 루프: 가는 선 → 넓어짐 + 점 등장 → 끌림(파랑) → 되돌아옴 ──
.hg.is-demo .hg__hair {
  animation-name: hg-hair;
  animation-duration: $dur-loop;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
@keyframes hg-hair {
  0%, 10% { transform: translateX(-10px) scaleX(.1); background: $subject-ink; }
  26%, 34% { transform: translateX(-10px) scaleX(1); background: $subject-ink; }
  44%, 72% { transform: translateX(-10px) scaleX(1); background: $subject-blue; }
  86%, 100% { transform: translateX(-10px) scaleX(.1); background: $subject-ink; }
}
.hg.is-demo .hg__dots {
  animation-name: hg-dots;
  animation-duration: $dur-loop;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
@keyframes hg-dots {
  0%, 12% { opacity: 0; transform: scale(.5); }
  28%, 74% { opacity: 1; transform: scale(1); }
  86%, 100% { opacity: 0; transform: scale(.5); }
}
.hg.is-demo {
  animation-name: hg-split;
  animation-duration: $dur-loop;
  animation-timing-function: $easing;
  animation-iteration-count: infinite;
}
@keyframes hg-split {
  0%, 40% { --split: 46%; }
  70% { --split: 66%; }
  86%, 100% { --split: 46%; }
}

@media (prefers-reduced-motion: reduce) {
  .hg.is-demo,
  .hg.is-demo .hg__hair,
  .hg.is-demo .hg__dots { animation: none !important; }
  .hg__hair, .hg__dots { transition: none; }
}

@media (max-width: 340px) {
  .hg__box { height: 104px; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

@property --split {
  syntax: "<percentage>";
  inherits: true;
  initial-value: 46%;
}
.hg {
  --split: 46%;
  width: min(300px, 88vw);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.hg__box {
  display: grid;
  grid-template-columns: var(--split) 20px 1fr;
  height: 120px;
  border-radius: 16px;
  overflow: hidden;
  background: rgba(23, 20, 26, 0.2);
}

.hg__pane {
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 8px;
  padding: 12px;
  overflow: hidden;
}

.hg__ln {
  flex: 0 0 auto;
  height: 8px;
  border-radius: 4px;
  background: rgba(23, 20, 26, 0.2);
}

.hg__ln--d {
  background: rgba(255, 247, 230, 0.32);
}

.hg__ln--s {
  width: 58%;
}

.hg__pane--l {
  background: rgba(255, 247, 230, 0.9);
}

.hg__pane--r {
  background: rgba(23, 20, 26, 0.78);
}

.hg__bar {
  position: relative;
  display: grid;
  place-items: center;
  background: transparent;
  cursor: col-resize;
  touch-action: none;
}

.hg__hair {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 20px;
  border-radius: 999px;
  background: #17141a;
  transform: translateX(-10px) scaleX(0.1);
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1), background 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.hg__dots {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 4px;
  opacity: 0;
  transform: scale(0.5);
  transition: opacity 220ms cubic-bezier(0.2, 0.8, 0.2, 1), transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.hg__dots s {
  display: block;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: #fff7e6;
}

.hg.is-near .hg__hair,
.hg__bar:hover .hg__hair {
  transform: translateX(-10px) scaleX(1);
}

.hg.is-near .hg__dots,
.hg__bar:hover .hg__dots {
  opacity: 1;
  transform: scale(1);
}

.hg.is-drag .hg__hair {
  background: #2f6df6;
}

.hg__bar:focus-visible {
  outline: 2px solid #17141a;
  outline-offset: -2px;
}

.hg__cap {
  margin: 0;
  font-size: 11px;
  line-height: 14px;
  font-weight: 700;
  color: #17141a;
  text-align: center;
}

.hg.is-demo .hg__hair {
  animation-name: hg-hair;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
}

@keyframes hg-hair {
  0%, 10% {
    transform: translateX(-10px) scaleX(0.1);
    background: #17141a;
  }
  26%, 34% {
    transform: translateX(-10px) scaleX(1);
    background: #17141a;
  }
  44%, 72% {
    transform: translateX(-10px) scaleX(1);
    background: #2f6df6;
  }
  86%, 100% {
    transform: translateX(-10px) scaleX(0.1);
    background: #17141a;
  }
}
.hg.is-demo .hg__dots {
  animation-name: hg-dots;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
}

@keyframes hg-dots {
  0%, 12% {
    opacity: 0;
    transform: scale(0.5);
  }
  28%, 74% {
    opacity: 1;
    transform: scale(1);
  }
  86%, 100% {
    opacity: 0;
    transform: scale(0.5);
  }
}
.hg.is-demo {
  animation-name: hg-split;
  animation-duration: 2s;
  animation-timing-function: cubic-bezier(0.2, 0.8, 0.2, 1);
  animation-iteration-count: infinite;
}

@keyframes hg-split {
  0%, 40% {
    --split: 46%;
  }
  70% {
    --split: 66%;
  }
  86%, 100% {
    --split: 46%;
  }
}
@media (prefers-reduced-motion: reduce) {
  .hg.is-demo,
  .hg.is-demo .hg__hair,
  .hg.is-demo .hg__dots {
    animation: none !important;
  }
  .hg__hair, .hg__dots {
    transition: none;
  }
}
@media (max-width: 340px) {
  .hg__box {
    height: 104px;
  }
}

// 실제 동작: 손잡이 상태는 CSS 가 그린다. JS 는 끌기 시작·끝만 클래스로 알려 준다.
var root = document.getElementById('hg-root');
var box = document.getElementById('hg-box');
var bar = document.getElementById('hg-bar');
var dragging = false;

function set(pct) {
  var v = Math.max(20, Math.min(pct, 80));
  root.style.setProperty('--split', v.toFixed(1) + '%');
  bar.setAttribute('aria-valuenow', String(Math.round(v)));
}
bar.addEventListener('pointerenter', function () { root.classList.add('is-near'); });
bar.addEventListener('pointerleave', function () { if (!dragging) root.classList.remove('is-near'); });
bar.addEventListener('pointerdown', function (e) {
  root.classList.remove('is-demo');
  dragging = true;
  root.classList.add('is-drag');
  bar.setPointerCapture(e.pointerId);
  e.preventDefault();
});
bar.addEventListener('pointermove', function (e) {
  if (!dragging) return;
  set((e.clientX - box.getBoundingClientRect().left) / box.clientWidth * 100);
});
function drop() {
  dragging = false;
  root.classList.remove('is-drag');
  root.classList.remove('is-near');
}
bar.addEventListener('pointerup', drop);
bar.addEventListener('pointercancel', drop);
bar.addEventListener('keydown', function (e) {
  var d = e.key === 'ArrowLeft' ? -4 : e.key === 'ArrowRight' ? 4 : 0;
  if (!d) return;
  root.classList.remove('is-demo');
  set(Number(bar.getAttribute('aria-valuenow')) + d);
  bar.focus({ preventScroll: true });
  e.preventDefault();
});

import { useRef, useState } from "react";
import type { CSSProperties } from "react";
import styles from "./GripHandle.module.scss";

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

type PEvt = { clientX: number; pointerId: number; preventDefault(): void; currentTarget: { setPointerCapture(id: number): void } };
type KeyEvt = { key: string; preventDefault(): void };
type Vars = CSSProperties & { "--split"?: string; "--duration"?: string; "--easing"?: string; "--color"?: string };

export default function GripHandle({
  start = 46,
  duration = 220,
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#2f6df6",
}: GripHandleProps) {
  const [split, setSplit] = useState(start);
  const [near, setNear] = useState(false);
  const [drag, setDrag] = useState(false);
  const boxRef = useRef<HTMLDivElement>(null);

  function set(pct: number): void { setSplit(Math.max(20, Math.min(pct, 80))); }
  function onDown(e: PEvt): void {
    setDrag(true);
    e.currentTarget.setPointerCapture(e.pointerId);
    e.preventDefault();
  }
  function onMove(e: PEvt): void {
    const box = boxRef.current;
    if (!drag || !box) return;
    set(((e.clientX - box.getBoundingClientRect().left) / box.clientWidth) * 100);
  }
  function onUp(): void { setDrag(false); setNear(false); }
  function onKey(e: KeyEvt): void {
    const d = e.key === "ArrowLeft" ? -4 : e.key === "ArrowRight" ? 4 : 0;
    if (!d) return;
    set(split + d);
    e.preventDefault();
  }

  const vars: Vars = {
    "--split": `${split.toFixed(1)}%`,
    "--duration": `${duration}ms`,
    "--easing": easing,
    "--color": color,
  };
  const cls = [styles.hg, near ? styles.isNear : "", drag ? styles.isDrag : ""].join(" ").trim();

  return (
    <div className={cls} style={vars}>
      <div className={styles.box} ref={boxRef}>
        <section className={`${styles.pane} ${styles.paneL}`} aria-label="Left pane">
          <span className={styles.ln} />
          <span className={`${styles.ln} ${styles.lnShort}`} />
          <span className={styles.ln} />
        </section>
        <div
          className={styles.bar}
          role="separator"
          tabIndex={0}
          aria-orientation="vertical"
          aria-label="Split width"
          aria-valuemin={20}
          aria-valuemax={80}
          aria-valuenow={Math.round(split)}
          onPointerEnter={(): void => setNear(true)}
          onPointerLeave={(): void => { if (!drag) setNear(false); }}
          onPointerDown={onDown}
          onPointerMove={onMove}
          onPointerUp={onUp}
          onPointerCancel={onUp}
          onKeyDown={onKey}
        >
          <i className={styles.hair} aria-hidden="true" />
          <i className={styles.dots} aria-hidden="true"><s /><s /><s /></i>
        </div>
        <section className={`${styles.pane} ${styles.paneR}`} aria-label="Right pane">
          <span className={`${styles.ln} ${styles.lnDark}`} />
          <span className={`${styles.ln} ${styles.lnDark} ${styles.lnShort}`} />
        </section>
      </div>
      <p className={styles.cap}>It widens on hover and stays lit while you drag</p>
    </div>
  );
}