Sleeve Rail

Installation#

CLI

npx shadcn@latest add https://hantui-theta.vercel.app/r/sleeve-rail.json

Manual

1. Install the dependencies

   npmpnpmbunyarn

   npm install clsx lucide-react motion tailwind-merge

2. Add the shared helpers

   Components use cn() from lib/utils.ts and the motion tokens below. See Installation if you have not set them up yet.

   lib/gallery/gallery-a11y.tsx

   import { useEffect, useRef } from "react";
   import type { GalleryItem } from "@/lib/gallery/types";
   
   export interface GalleryA11yProps {
     items: GalleryItem[];
     /** Active item. */
     index: number;
     /** Names the list, e.g. "Album covers". */
     label: string;
     /** Focusing an item's button (Tab, screen reader cursor) moves the gallery to it. */
     onFocusItem?: (index: number) => void;
     /** Clicking an item's button or pressing Enter on it. */
     onActivate?: (index: number) => void;
     /** Announce index changes politely. Turn off while autoplay runs so it doesn't talk over the user. @default true */
     live?: boolean;
   }
   
   const describe = (item: GalleryItem, index: number, total: number) =>
     [`${index + 1} of ${total}`, item.title, item.subtitle, item.alt].filter(Boolean).join(". ");
   
   /**
    * The accessible side of a canvas gallery: a visually hidden list of buttons, one per item, kept
    * in sync with the active index (roving tabindex, focus follows arrow keys), plus a polite live
    * region that names the active item. The canvas itself stays aria-hidden.
    */
   export function GalleryA11y({ items, index, label, onFocusItem, onActivate, live = true }: GalleryA11yProps) {
     const list = useRef<HTMLUListElement>(null);
   
     // When the active item changes while focus is in the list (arrow keys), move focus with it.
     useEffect(() => {
       const element = list.current;
       if (!element || !element.contains(document.activeElement)) return;
       element.querySelectorAll<HTMLButtonElement>("button")[index]?.focus({ preventScroll: true });
     }, [index]);
   
     const active = items[index];
     return (
       <div className="sr-only">
         <ul ref={list} aria-label={label}>
           {items.map((item, i) => (
             <li key={`${item.src}-${i}`}>
               <button
                 type="button"
                 tabIndex={i === index ? 0 : -1}
                 aria-current={i === index ? "true" : undefined}
                 onFocus={() => {
                   if (i !== index) onFocusItem?.(i);
                 }}
                 onClick={() => onActivate?.(i)}
               >
                 {describe(item, i, items.length)}
               </button>
             </li>
           ))}
         </ul>
         <p aria-live={live ? "polite" : "off"} aria-atomic="true">
           {active ? `${active.title ?? active.alt}, ${index + 1} of ${items.length}` : ""}
         </p>
       </div>
     );
   }

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   lib/gallery/gallery-chrome.tsx

   import { useState } from "react";
   import { AnimatePresence, motion, useReducedMotion } from "motion/react";
   import { ChevronLeft, ChevronRight } from "lucide-react";
   import { duration, ease } from "@/lib/motion";
   import { cn } from "@/lib/utils";
   import type { GalleryItem } from "@/lib/gallery/types";
   
   /** "light" = a light (or transparent) background that needs dark text; "dark" = a dark one. */
   export type ChromeScheme = "light" | "dark";
   
   /**
    * Picks caption and control colors for a background. Understands hex and rgb()/rgba(); anything
    * else (named colors, var()) and transparent backgrounds count as light, like the page itself.
    */
   export function chromeScheme(background?: string): ChromeScheme {
     if (!background) return "light";
     const value = background.trim().toLowerCase();
     let rgb: number[] | null = null;
     let alpha = 1;
     const hex = value.match(/^#([0-9a-f]{3,8})$/);
     if (hex) {
       const h = hex[1];
       const full = h.length <= 4 ? [...h].map((c) => c + c).join("") : h;
       rgb = [0, 2, 4].map((i) => parseInt(full.slice(i, i + 2), 16));
       if (full.length === 8) alpha = parseInt(full.slice(6, 8), 16) / 255;
     }
     const fn = value.match(/^rgba?\(([^)]+)\)$/);
     if (fn) {
       const parts = fn[1].split(/[\s,/]+/).filter(Boolean).map(parseFloat);
       rgb = parts.slice(0, 3);
       if (parts.length > 3) alpha = parts[3] > 1 ? parts[3] / 100 : parts[3];
     }
     if (!rgb || alpha < 0.5) return "light";
     const [r, g, b] = rgb.map((c) => {
       const s = c / 255;
       return s <= 0.04045 ? s / 12.92 : ((s + 0.055) / 1.055) ** 2.4;
     });
     return 0.2126 * r + 0.7152 * g + 0.0722 * b < 0.25 ? "dark" : "light";
   }
   
   export interface GalleryCaptionProps {
     item: GalleryItem | undefined;
     index: number;
     /** Item count, so wrapping from last to first slides the right way. */
     count: number;
     scheme?: ChromeScheme;
     className?: string;
   }
   
   /**
    * Title and subtitle of the active item. It slides in from the direction of travel. Screen readers
    * get the same text from the gallery's live region, so this copy is aria-hidden.
    */
   export function GalleryCaption({ item, index, count, scheme = "light", className }: GalleryCaptionProps) {
     const reduceMotion = useReducedMotion();
     const [previous, setPrevious] = useState(index);
     const [direction, setDirection] = useState(1);
     if (previous !== index) {
       let delta = index - previous;
       if (count > 2 && Math.abs(delta) > count / 2) delta -= Math.sign(delta) * count;
       setDirection(delta >= 0 ? 1 : -1);
       setPrevious(index);
     }
     const shift = reduceMotion ? 0 : 14;
     return (
       <div aria-hidden="true" className={cn("relative h-10 min-w-0 overflow-hidden", className)}>
         <AnimatePresence initial={false} custom={direction} mode="popLayout">
           <motion.div
             key={index}
             custom={direction}
             variants={{
               enter: (d: number) => ({ opacity: 0, x: shift * d, filter: reduceMotion ? "blur(0px)" : "blur(4px)" }),
               center: { opacity: 1, x: 0, filter: "blur(0px)" },
               exit: (d: number) => ({ opacity: 0, x: -shift * d, filter: reduceMotion ? "blur(0px)" : "blur(4px)" }),
             }}
             initial="enter"
             animate="center"
             exit="exit"
             transition={{ duration: duration.base, ease: ease.out }}
             className="absolute inset-0"
           >
             <p className={cn("truncate text-sm font-medium", scheme === "dark" ? "text-white" : "text-foreground")}>{item?.title ?? item?.alt}</p>
             {item?.subtitle ? <p className={cn("truncate text-[13px]", scheme === "dark" ? "text-white/65" : "text-muted-foreground")}>{item.subtitle}</p> : null}
           </motion.div>
         </AnimatePresence>
       </div>
     );
   }
   
   export interface GalleryControlsProps {
     index: number;
     count: number;
     onPrevious: () => void;
     onNext: () => void;
     scheme?: ChromeScheme;
     /** Disable the buttons at the ends of a gallery that doesn't loop. @default false */
     bounded?: boolean;
     className?: string;
   }
   
   /** Previous / next buttons with an "n / total" counter. */
   export function GalleryControls({ index, count, onPrevious, onNext, scheme = "light", bounded = false, className }: GalleryControlsProps) {
     const button = cn(
       "grid size-10 cursor-pointer place-items-center rounded-full border transition-[background-color,opacity,transform] duration-150 outline-none active:scale-[0.94] disabled:pointer-events-none disabled:opacity-35 focus-visible:ring-2 focus-visible:ring-ring motion-reduce:transition-none",
       scheme === "dark" ? "border-white/20 bg-white/10 text-white hover:bg-white/20" : "border-border bg-background/80 text-foreground hover:bg-surface-2",
     );
     return (
       <div data-gallery-control className={cn("flex shrink-0 items-center gap-1.5", className)}>
         <button type="button" data-gallery-control aria-label="Previous" onClick={onPrevious} disabled={bounded && index <= 0} className={button}>
           <ChevronLeft className="size-4" aria-hidden="true" />
         </button>
         <span aria-hidden="true" className={cn("min-w-14 text-center font-mono text-[13px] tabular-nums", scheme === "dark" ? "text-white/75" : "text-muted-foreground")}>
           {index + 1} / {count}
         </span>
         <button type="button" data-gallery-control aria-label="Next" onClick={onNext} disabled={bounded && index >= count - 1} className={button}>
           <ChevronRight className="size-4" aria-hidden="true" />
         </button>
       </div>
     );
   }

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   lib/gallery/gallery-fallback.tsx

   import { cn } from "@/lib/utils";
   import type { GalleryItem } from "@/lib/gallery/types";
   
   export interface GalleryFallbackProps {
     items: GalleryItem[];
     /** Names the list. */
     label: string;
     /** CSS aspect ratio of each image. @default "4 / 5" */
     aspect?: string;
     onSelect?: (item: GalleryItem, index: number) => void;
     className?: string;
   }
   
   /** What a gallery shows without WebGL: the same items as a plain, swipeable scroll-snap list. */
   export function GalleryFallback({ items, label, aspect = "4 / 5", onSelect, className }: GalleryFallbackProps) {
     return (
       <ul aria-label={label} className={cn("flex size-full snap-x snap-mandatory items-center gap-4 overflow-x-auto px-6 py-6 [scrollbar-width:thin]", className)}>
         {items.map((item, i) => (
           <li key={`${item.src}-${i}`} className="w-[min(70%,15rem)] shrink-0 snap-center">
             <figure>
               {onSelect ? (
                 <button type="button" onClick={() => onSelect(item, i)} className="block w-full cursor-pointer rounded-xl outline-none focus-visible:ring-2 focus-visible:ring-ring">
                   {/* eslint-disable-next-line @next/next/no-img-element -- plain img keeps the component framework-agnostic */}
                   <img src={item.src} alt={item.alt} loading="lazy" decoding="async" className="w-full rounded-xl object-cover shadow-md" style={{ aspectRatio: aspect }} />
                 </button>
               ) : (
                 // eslint-disable-next-line @next/next/no-img-element -- plain img keeps the component framework-agnostic
                 <img src={item.src} alt={item.alt} loading="lazy" decoding="async" className="w-full rounded-xl object-cover shadow-md" style={{ aspectRatio: aspect }} />
               )}
               {item.title ? (
                 <figcaption className="mt-2 text-sm">
                   <span className="font-medium text-foreground">{item.title}</span>
                   {item.subtitle ? <span className="block text-muted-foreground">{item.subtitle}</span> : null}
                 </figcaption>
               ) : null}
             </figure>
           </li>
         ))}
       </ul>
     );
   }

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   lib/gallery/math.ts

   /** Column-major 4×4 matrices for the gallery renderer (no dependencies). */
   export type Mat4 = Float32Array;
   
   export const createMat4 = (): Mat4 => {
     const m = new Float32Array(16);
     m[0] = m[5] = m[10] = m[15] = 1;
     return m;
   };
   
   /** out = a × b */
   export function multiply(out: Mat4, a: Mat4, b: Mat4) {
     for (let col = 0; col < 4; col++) {
       const b0 = b[col * 4];
       const b1 = b[col * 4 + 1];
       const b2 = b[col * 4 + 2];
       const b3 = b[col * 4 + 3];
       out[col * 4] = a[0] * b0 + a[4] * b1 + a[8] * b2 + a[12] * b3;
       out[col * 4 + 1] = a[1] * b0 + a[5] * b1 + a[9] * b2 + a[13] * b3;
       out[col * 4 + 2] = a[2] * b0 + a[6] * b1 + a[10] * b2 + a[14] * b3;
       out[col * 4 + 3] = a[3] * b0 + a[7] * b1 + a[11] * b2 + a[15] * b3;
     }
     return out;
   }
   
   export function perspective(out: Mat4, fovy: number, aspect: number, near: number, far: number) {
     const f = 1 / Math.tan(fovy / 2);
     out.fill(0);
     out[0] = f / aspect;
     out[5] = f;
     out[10] = (far + near) / (near - far);
     out[11] = -1;
     out[14] = (2 * far * near) / (near - far);
     return out;
   }
   
   export function lookAt(out: Mat4, eye: readonly number[], target: readonly number[], up: readonly number[] = [0, 1, 0]) {
     let zx = eye[0] - target[0];
     let zy = eye[1] - target[1];
     let zz = eye[2] - target[2];
     let len = Math.hypot(zx, zy, zz) || 1;
     zx /= len;
     zy /= len;
     zz /= len;
     let xx = up[1] * zz - up[2] * zy;
     let xy = up[2] * zx - up[0] * zz;
     let xz = up[0] * zy - up[1] * zx;
     len = Math.hypot(xx, xy, xz) || 1;
     xx /= len;
     xy /= len;
     xz /= len;
     const yx = zy * xz - zz * xy;
     const yy = zz * xx - zx * xz;
     const yz = zx * xy - zy * xx;
     out[0] = xx;
     out[1] = yx;
     out[2] = zx;
     out[3] = 0;
     out[4] = xy;
     out[5] = yy;
     out[6] = zy;
     out[7] = 0;
     out[8] = xz;
     out[9] = yz;
     out[10] = zz;
     out[11] = 0;
     out[12] = -(xx * eye[0] + xy * eye[1] + xz * eye[2]);
     out[13] = -(yx * eye[0] + yy * eye[1] + yz * eye[2]);
     out[14] = -(zx * eye[0] + zy * eye[1] + zz * eye[2]);
     out[15] = 1;
     return out;
   }
   
   /**
    * Model matrix: translate × rotateY × rotateX × rotateZ × flip × uniform scale. Angles in radians.
    * `flip` turns the card around its own vertical axis before the other rotations (turning a leaning card over).
    */
   export function compose(out: Mat4, x: number, y: number, z: number, rx: number, ry: number, rz: number, s: number, flip = 0) {
     const cx = Math.cos(rx);
     const sx = Math.sin(rx);
     const cy = Math.cos(ry);
     const sy = Math.sin(ry);
     const cz = Math.cos(rz);
     const sz = Math.sin(rz);
     out[0] = (cy * cz + sy * sx * sz) * s;
     out[1] = cx * sz * s;
     out[2] = (-sy * cz + cy * sx * sz) * s;
     out[3] = 0;
     out[4] = (-cy * sz + sy * sx * cz) * s;
     out[5] = cx * cz * s;
     out[6] = (sy * sz + cy * sx * cz) * s;
     out[7] = 0;
     out[8] = sy * cx * s;
     out[9] = -sx * s;
     out[10] = cy * cx * s;
     out[11] = 0;
     if (flip) {
       // Right-multiply by a rotation about local y: column 0 and column 2 mix.
       const cf = Math.cos(flip);
       const sf = Math.sin(flip);
       for (let row = 0; row < 3; row++) {
         const c0 = out[row];
         const c2 = out[8 + row];
         out[row] = c0 * cf - c2 * sf;
         out[8 + row] = c0 * sf + c2 * cf;
       }
     }
     out[12] = x;
     out[13] = y;
     out[14] = z;
     out[15] = 1;
     return out;
   }
   
   /** Inverts m into out. Returns false (leaving out untouched) when m is singular. */
   export function invert(out: Mat4, m: Mat4) {
     const [a00, a01, a02, a03, a10, a11, a12, a13, a20, a21, a22, a23, a30, a31, a32, a33] = m;
     const b00 = a00 * a11 - a01 * a10;
     const b01 = a00 * a12 - a02 * a10;
     const b02 = a00 * a13 - a03 * a10;
     const b03 = a01 * a12 - a02 * a11;
     const b04 = a01 * a13 - a03 * a11;
     const b05 = a02 * a13 - a03 * a12;
     const b06 = a20 * a31 - a21 * a30;
     const b07 = a20 * a32 - a22 * a30;
     const b08 = a20 * a33 - a23 * a30;
     const b09 = a21 * a32 - a22 * a31;
     const b10 = a21 * a33 - a23 * a31;
     const b11 = a22 * a33 - a23 * a32;
     let det = b00 * b11 - b01 * b10 + b02 * b09 + b03 * b08 - b04 * b07 + b05 * b06;
     if (!det) return false;
     det = 1 / det;
     out[0] = (a11 * b11 - a12 * b10 + a13 * b09) * det;
     out[1] = (a02 * b10 - a01 * b11 - a03 * b09) * det;
     out[2] = (a31 * b05 - a32 * b04 + a33 * b03) * det;
     out[3] = (a22 * b04 - a21 * b05 - a23 * b03) * det;
     out[4] = (a12 * b08 - a10 * b11 - a13 * b07) * det;
     out[5] = (a00 * b11 - a02 * b08 + a03 * b07) * det;
     out[6] = (a32 * b02 - a30 * b05 - a33 * b01) * det;
     out[7] = (a20 * b05 - a22 * b02 + a23 * b01) * det;
     out[8] = (a10 * b10 - a11 * b08 + a13 * b06) * det;
     out[9] = (a01 * b08 - a00 * b10 - a03 * b06) * det;
     out[10] = (a30 * b04 - a31 * b02 + a33 * b00) * det;
     out[11] = (a21 * b02 - a20 * b04 - a23 * b00) * det;
     out[12] = (a11 * b07 - a10 * b09 - a12 * b06) * det;
     out[13] = (a00 * b09 - a01 * b07 + a02 * b06) * det;
     out[14] = (a31 * b01 - a30 * b03 - a32 * b00) * det;
     out[15] = (a20 * b03 - a21 * b01 + a22 * b00) * det;
     return true;
   }
   
   /** m × (x, y, z, w) */
   export function transform(m: Mat4, x: number, y: number, z: number, w = 1): [number, number, number, number] {
     return [
       m[0] * x + m[4] * y + m[8] * z + m[12] * w,
       m[1] * x + m[5] * y + m[9] * z + m[13] * w,
       m[2] * x + m[6] * y + m[10] * z + m[14] * w,
       m[3] * x + m[7] * y + m[11] * z + m[15] * w,
     ];
   }
   
   export const clamp = (value: number, min: number, max: number) => (value < min ? min : value > max ? max : value);
   export const lerp = (a: number, b: number, t: number) => a + (b - a) * t;
   export const smoothstep = (edge0: number, edge1: number, x: number) => {
     const t = clamp((x - edge0) / (edge1 - edge0), 0, 1);
     return t * t * (3 - 2 * t);
   };
   /** Positive modulo, e.g. for wrapping indexes. */
   export const wrap = (value: number, length: number) => ((value % length) + length) % length;

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   lib/gallery/renderer.ts

   import { clamp, compose, createMat4, invert, lookAt, multiply, perspective, transform, type Mat4 } from "@/lib/gallery/math";
   
   /**
    * One textured card in world space. Units are CSS pixels: with the default camera, a card at
    * z = 0 that is 200 wide covers 200 CSS pixels on screen. Angles are radians; y points up.
    */
   export interface GalleryCard {
     /** Index into the renderer's image list, or -1 for an untextured card. */
     image: number;
     x: number;
     y: number;
     z: number;
     rotateX?: number;
     rotateY?: number;
     rotateZ?: number;
     /** Uniform scale. @default 1 */
     scale?: number;
     /** Turn around the card's own vertical axis, applied before the other rotations (radians). @default 0 */
     flip?: number;
     width: number;
     height: number;
     /** Corner radius in px. @default 12 */
     radius?: number;
     /** 0 keeps `radius`, 1 rounds fully (circle for square cards). @default 0 */
     round?: number;
     /** Fades the card toward the background. @default 1 */
     opacity?: number;
     /** Darkens the card (0–1). @default 0 */
     dim?: number;
     /** 0 = monochrome and low contrast, 1 = full color (develop effect). @default 1 */
     tone?: number;
     /** Soft drop shadow strength (0–1). @default 0 */
     shadow?: number;
     /** Floor reflection strength (0–1); needs `floorY` in the scene. @default 0 */
     reflection?: number;
     /** Accent ring strength (0–1). @default 0 */
     ring?: number;
     /** Paper border in px around the image (print look). @default 0 */
     border?: number;
     /** Shifts the cover crop, -1 to 1 per axis (parallax drift inside the frame). @default 0 */
     panX?: number;
     panY?: number;
     /** Flat color mixed over the card, [r, g, b, amount] in 0–1 (e.g. a card's back). */
     fill?: readonly [number, number, number, number];
     /** Returned by `pick`. @default the card's position in the list */
     id?: number;
   }
   
   export interface GalleryScene {
     /** Vertical field of view in degrees. @default 30 */
     fov?: number;
     /** Camera position and target. The default camera sits on +z so that z = 0 maps 1:1 to CSS px. */
     camera?: { x?: number; y?: number; z?: number; targetX?: number; targetY?: number; targetZ?: number };
     /** World y of the reflection floor. */
     floorY?: number;
     /** Distance below the floor over which reflections fade out, px. @default 160 */
     reflectionFade?: number;
     /** Shadow offset (down) and blur in px. @default 14 and 22 */
     shadowOffset?: number;
     shadowBlur?: number;
     /** Shadow opacity at strength 1. @default 0.28 */
     shadowOpacity?: number;
     /** Fades everything toward the left/right and top/bottom edges, as a fraction of the size. */
     edgeFade?: readonly [number, number];
     /** Colors as [r, g, b] in 0–1. */
     placeholder?: readonly [number, number, number];
     paper?: readonly [number, number, number];
     ring?: readonly [number, number, number];
   }
   
   export interface PickResult {
     id: number;
     /** Hit point in the card's local space, 0–1 from the bottom-left corner. */
     u: number;
     v: number;
   }
   
   const FLOATS = 40;
   const KIND_CARD = 0;
   const KIND_SHADOW = 1;
   const KIND_REFLECTION = 2;
   
   const VERTEX = /* glsl */ `#version 300 es
   layout(location = 0) in vec2 a_corner;
   layout(location = 1) in mat4 a_model;
   layout(location = 5) in vec4 a_size;
   layout(location = 6) in vec4 a_look;
   layout(location = 7) in vec4 a_extra;
   layout(location = 8) in vec4 a_meta;
   layout(location = 9) in vec4 a_uv;
   layout(location = 10) in vec4 a_fill;
   uniform mat4 u_viewProj;
   uniform float u_floorY;
   uniform float u_shadowOffset;
   uniform float u_shadowBlur;
   out vec2 v_local;
   out vec2 v_uv;
   out float v_worldY;
   flat out vec4 v_size;
   flat out vec4 v_look;
   flat out vec4 v_extra;
   flat out vec4 v_meta;
   flat out vec4 v_uvRect;
   flat out vec4 v_fill;
   void main() {
     float kind = a_meta.x;
     bool shadow = kind > 0.5 && kind < 1.5;
     // Grow the quad past the card so edges antialias fully and shadows have room to blur.
     float margin = shadow ? u_shadowBlur * 2.0 : 2.0;
     vec2 local = a_corner * (a_size.xy + margin * 2.0);
     vec4 world = a_model * vec4(local, 0.0, 1.0);
     if (shadow) { world.y -= u_shadowOffset; world.z -= 0.5; }
     if (kind > 1.5) world.y = 2.0 * u_floorY - world.y;
     v_worldY = world.y;
     v_local = local;
     v_uv = local / a_size.xy + 0.5;
     v_size = a_size;
     v_look = a_look;
     v_extra = a_extra;
     v_meta = a_meta;
     v_uvRect = a_uv;
     v_fill = a_fill;
     gl_Position = u_viewProj * world;
   }`;
   
   const FRAGMENT = /* glsl */ `#version 300 es
   precision highp float;
   precision highp sampler2DArray;
   uniform sampler2DArray u_images;
   uniform vec2 u_resolution;
   uniform vec2 u_edgeFade;
   uniform vec3 u_placeholder;
   uniform vec3 u_paper;
   uniform vec3 u_ring;
   uniform float u_floorY;
   uniform float u_reflectFade;
   uniform float u_shadowBlur;
   uniform float u_shadowOpacity;
   in vec2 v_local;
   in vec2 v_uv;
   in float v_worldY;
   flat in vec4 v_size;   // width, height, radius, round
   flat in vec4 v_look;   // opacity, dim, tone, ring
   flat in vec4 v_extra;  // layer, loaded, border, shadow
   flat in vec4 v_meta;   // kind, reflection
   flat in vec4 v_uvRect; // u0, v0, u1, v1 inside the texture layer
   flat in vec4 v_fill;   // r, g, b, amount
   out vec4 fragColor;
   
   float roundRect(vec2 p, vec2 halfSize, float r) {
     vec2 q = abs(p) - halfSize + r;
     return length(max(q, 0.0)) + min(max(q.x, q.y), 0.0) - r;
   }
   
   void main() {
     vec2 halfSize = v_size.xy * 0.5;
     float maxRadius = min(halfSize.x, halfSize.y);
     float radius = mix(min(v_size.z, maxRadius), maxRadius, v_size.w);
     float d = roundRect(v_local, halfSize, radius);
     float kind = v_meta.x;
   
     vec2 screen = gl_FragCoord.xy / u_resolution;
     float fade = 1.0;
     if (u_edgeFade.x > 0.0) fade *= smoothstep(0.0, u_edgeFade.x, screen.x) * smoothstep(0.0, u_edgeFade.x, 1.0 - screen.x);
     if (u_edgeFade.y > 0.0) fade *= smoothstep(0.0, u_edgeFade.y, screen.y) * smoothstep(0.0, u_edgeFade.y, 1.0 - screen.y);
   
     if (kind > 0.5 && kind < 1.5) {
       float blur = max(u_shadowBlur, 1.0);
       float a = 1.0 - smoothstep(-blur, blur, d);
       a *= a * v_extra.w * u_shadowOpacity * v_look.x * fade;
       fragColor = vec4(0.0, 0.0, 0.0, a);
       return;
     }
   
     float aa = max(fwidth(d), 1e-3);
     float coverage = 1.0 - smoothstep(-aa * 0.5, aa * 0.5, d);
     if (coverage <= 0.0) discard;
   
     float border = v_extra.z;
     vec2 inner = max(halfSize - border, vec2(1.0));
     bool paper = border > 0.0 && (abs(v_local.x) > inner.x || abs(v_local.y) > inner.y);
     vec3 color = u_placeholder;
     float texAlpha = 1.0;
     if (v_extra.x >= 0.0 && !paper) {
       vec2 uv = border > 0.0 ? v_local / (inner * 2.0) + 0.5 : v_uv;
       // Layers are premultiplied; transparent images (overlays, cut-outs) keep their alpha.
       vec4 texel = texture(u_images, vec3(mix(v_uvRect.xy, v_uvRect.zw, uv), v_extra.x));
       vec3 tex = texel.a > 0.001 ? texel.rgb / texel.a : vec3(0.0);
       color = mix(u_placeholder, tex, v_extra.y);
       texAlpha = mix(1.0, texel.a, v_extra.y);
     }
     if (paper) color = u_paper;
   
     float tone = v_look.z;
     if (tone < 1.0 && !paper) {
       float gray = dot(color, vec3(0.299, 0.587, 0.114));
       if (border > 0.0) {
         // A print develops out of its paper: blank, then faint monochrome, then full color.
         vec3 mono = mix(u_paper, vec3(gray), smoothstep(0.0, 0.6, tone));
         color = mix(mono, color, smoothstep(0.45, 1.0, tone));
       } else {
         color = mix(vec3(mix(0.55, gray, 0.5)), color, tone);
       }
     }
     color = mix(color, v_fill.rgb, v_fill.a);
     color *= 1.0 - v_look.y;
     if (v_look.w > 0.0) color = mix(color, u_ring, smoothstep(-2.0 - aa, -2.0, d) * v_look.w);
   
     float alpha = coverage * v_look.x * fade * texAlpha;
     if (kind > 1.5) {
       float below = u_floorY - v_worldY;
       alpha *= below < 0.0 ? 0.0 : v_meta.y * (1.0 - smoothstep(0.0, u_reflectFade, below));
     }
     fragColor = vec4(color * alpha, alpha);
   }`;
   
   function compile(gl: WebGL2RenderingContext, type: number, source: string) {
     const shader = gl.createShader(type);
     if (!shader) return null;
     gl.shaderSource(shader, source);
     gl.compileShader(shader);
     if (gl.getShaderParameter(shader, gl.COMPILE_STATUS)) return shader;
     if (process.env.NODE_ENV !== "production") console.error(`GalleryRenderer: shader failed to compile\n${gl.getShaderInfoLog(shader)}`);
     gl.deleteShader(shader);
     return null;
   }
   
   function createProgram(gl: WebGL2RenderingContext) {
     const vertex = compile(gl, gl.VERTEX_SHADER, VERTEX);
     const fragment = compile(gl, gl.FRAGMENT_SHADER, FRAGMENT);
     const program = vertex && fragment ? gl.createProgram() : null;
     if (program && vertex && fragment) {
       gl.attachShader(program, vertex);
       gl.attachShader(program, fragment);
       gl.linkProgram(program);
     }
     if (vertex) gl.deleteShader(vertex);
     if (fragment) gl.deleteShader(fragment);
     if (program && gl.getProgramParameter(program, gl.LINK_STATUS)) return program;
     if (program) gl.deleteProgram(program);
     return null;
   }
   
   interface TextureEntry {
     src: string;
     state: "loading" | "decoded" | "ready" | "error";
     image: HTMLImageElement | null;
     layer: number;
     aspect: number;
     /** Content rect inside the layer (images are fitted, not cropped): u0, v0, u1, v1. */
     content: [number, number, number, number];
     loadedAt: number;
     lastUsed: number;
   }
   
   /**
    * WebGL2 renderer for textured cards. Every card, its soft shadow and its floor reflection go
    * into one instanced draw over a texture array, sorted back to front for correct blending.
    * Images load once (crossOrigin "anonymous"), are fitted into fixed-size mipmapped layers and
    * recycled least-recently-used when there are more images than layers.
    */
   export class GalleryRenderer {
     readonly gl: WebGL2RenderingContext;
     readonly software: boolean;
     private program: WebGLProgram;
     private vao: WebGLVertexArrayObject;
     private quad: WebGLBuffer;
     private instances: WebGLBuffer;
     private texture: WebGLTexture;
     private uniforms: Record<string, WebGLUniformLocation | null> = {};
     private data = new Float32Array(FLOATS * 64);
     private capacity = 64;
     private entries = new Map<string, TextureEntry>();
     private freeLayers: number[] = [];
     private scratch: HTMLCanvasElement;
     private mipsDirty = false;
     private frame = 0;
     private images: string[] = [];
     private view = createMat4();
     private projection = createMat4();
     private viewProj = createMat4();
     private inverseViewProj = createMat4();
     private picks: { id: number; model: Mat4; width: number; height: number }[] = [];
     private models: Mat4[] = [];
     private cssWidth = 1;
     private cssHeight = 1;
     /** Called when an image finishes loading, so the owner can draw a new frame. */
     onImageLoad: () => void = () => {};
   
     private constructor(
       gl: WebGL2RenderingContext,
       readonly textureSize: number,
       readonly layers: number,
       software: boolean,
     ) {
       this.gl = gl;
       this.software = software;
       const program = createProgram(gl);
       const vao = gl.createVertexArray();
       const quad = gl.createBuffer();
       const instances = gl.createBuffer();
       const texture = gl.createTexture();
       if (!program || !vao || !quad || !instances || !texture) throw new Error("GalleryRenderer: WebGL setup failed");
       this.program = program;
       this.vao = vao;
       this.quad = quad;
       this.instances = instances;
       this.texture = texture;
       this.scratch = document.createElement("canvas");
       this.scratch.width = this.scratch.height = textureSize;
       this.setup();
     }
   
     /** Creates a renderer on `canvas`, or returns null when WebGL2 or the shaders are unavailable. */
     static create(canvas: HTMLCanvasElement, { textureSize = 512, layers = 32 }: { textureSize?: number; layers?: number } = {}) {
       const gl = canvas.getContext("webgl2", { alpha: true, antialias: false, depth: false, stencil: false, premultipliedAlpha: true });
       if (!gl) return null;
       const info = gl.getExtension("WEBGL_debug_renderer_info");
       const name = info ? String(gl.getParameter(info.UNMASKED_RENDERER_WEBGL)) : String(gl.getParameter(gl.RENDERER));
       const software = /swiftshader|llvmpipe|softpipe|software|basic render/i.test(name);
       const maxLayers = gl.getParameter(gl.MAX_ARRAY_TEXTURE_LAYERS) as number;
       try {
         return new GalleryRenderer(gl, textureSize, clamp(layers, 1, maxLayers), software);
       } catch {
         return null;
       }
     }
   
     private setup() {
       const { gl } = this;
       for (const name of ["u_viewProj", "u_floorY", "u_shadowOffset", "u_shadowBlur", "u_shadowOpacity", "u_images", "u_resolution", "u_edgeFade", "u_placeholder", "u_paper", "u_ring", "u_reflectFade"]) {
         this.uniforms[name] = gl.getUniformLocation(this.program, name);
       }
       gl.bindVertexArray(this.vao);
       gl.bindBuffer(gl.ARRAY_BUFFER, this.quad);
       gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-0.5, -0.5, 0.5, -0.5, 0.5, 0.5, -0.5, -0.5, 0.5, 0.5, -0.5, 0.5]), gl.STATIC_DRAW);
       gl.enableVertexAttribArray(0);
       gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
       gl.bindBuffer(gl.ARRAY_BUFFER, this.instances);
       gl.bufferData(gl.ARRAY_BUFFER, this.data.byteLength, gl.DYNAMIC_DRAW);
       const stride = FLOATS * 4;
       // mat4 model (locations 1–4), then six vec4s (5–10).
       for (let i = 0; i < 10; i++) {
         const location = i + 1;
         gl.enableVertexAttribArray(location);
         gl.vertexAttribPointer(location, 4, gl.FLOAT, false, stride, i * 16);
         gl.vertexAttribDivisor(location, 1);
       }
       gl.bindVertexArray(null);
   
       gl.bindTexture(gl.TEXTURE_2D_ARRAY, this.texture);
       const levels = Math.floor(Math.log2(this.textureSize)) + 1;
       gl.texStorage3D(gl.TEXTURE_2D_ARRAY, levels, gl.RGBA8, this.textureSize, this.textureSize, this.layers);
       gl.texParameteri(gl.TEXTURE_2D_ARRAY, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR);
       gl.texParameteri(gl.TEXTURE_2D_ARRAY, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
       gl.texParameteri(gl.TEXTURE_2D_ARRAY, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
       gl.texParameteri(gl.TEXTURE_2D_ARRAY, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
       const anisotropic = gl.getExtension("EXT_texture_filter_anisotropic");
       if (anisotropic) gl.texParameterf(gl.TEXTURE_2D_ARRAY, anisotropic.TEXTURE_MAX_ANISOTROPY_EXT, Math.min(4, gl.getParameter(anisotropic.MAX_TEXTURE_MAX_ANISOTROPY_EXT) as number));
       this.freeLayers = Array.from({ length: this.layers }, (_, i) => i);
       this.entries.forEach((entry) => {
         entry.layer = -1;
         if (entry.state === "ready") entry.state = "decoded";
       });
     }
   
     /** Rebuilds GPU resources after a lost WebGL context is restored. Images re-upload from memory. */
     restore() {
       const { gl } = this;
       const vao = gl.createVertexArray();
       const quad = gl.createBuffer();
       const instances = gl.createBuffer();
       const texture = gl.createTexture();
       if (!vao || !quad || !instances || !texture) return false;
       this.vao = vao;
       this.quad = quad;
       this.instances = instances;
       this.texture = texture;
       const program = createProgram(gl);
       if (!program) return false;
       this.program = program;
       this.capacity = this.data.length / FLOATS;
       this.setup();
       return true;
     }
   
     /** Image URLs that cards refer to by index. Unchanged URLs keep their textures. */
     setImages(images: string[]) {
       this.images = images;
     }
   
     resize(cssWidth: number, cssHeight: number, dpr: number) {
       const canvas = this.gl.canvas as HTMLCanvasElement;
       const width = Math.max(1, Math.round(cssWidth * dpr));
       const height = Math.max(1, Math.round(cssHeight * dpr));
       if (canvas.width !== width || canvas.height !== height) {
         canvas.width = width;
         canvas.height = height;
       }
       this.cssWidth = Math.max(1, cssWidth);
       this.cssHeight = Math.max(1, cssHeight);
     }
   
     private request(index: number) {
       const src = this.images[index];
       if (!src) return null;
       let entry = this.entries.get(src);
       if (!entry) {
         const created: TextureEntry = { src, state: "loading", image: null, layer: -1, aspect: 1, content: [0, 0, 1, 1], loadedAt: 0, lastUsed: 0 };
         entry = created;
         this.entries.set(src, created);
         const image = new Image();
         image.crossOrigin = "anonymous";
         image.decoding = "async";
         image.src = src;
         image.decode().then(
           () => {
             created.image = image;
             created.aspect = image.naturalWidth / Math.max(1, image.naturalHeight);
             created.state = "decoded";
             this.onImageLoad();
           },
           () => {
             created.state = "error";
           },
         );
       }
       entry.lastUsed = this.frame;
       return entry;
     }
   
     private upload(entry: TextureEntry) {
       if (!entry.image) return;
       let layer = this.freeLayers.pop();
       if (layer === undefined) {
         // Recycle the least recently used layer that no card showed this frame.
         let oldest: TextureEntry | null = null;
         this.entries.forEach((candidate) => {
           if (candidate.layer >= 0 && candidate.lastUsed < this.frame && (!oldest || candidate.lastUsed < oldest.lastUsed)) oldest = candidate;
         });
         const victim = oldest as TextureEntry | null;
         if (!victim) return;
         layer = victim.layer;
         victim.layer = -1;
         victim.state = "decoded";
       }
       const size = this.textureSize;
       const ctx = this.scratch.getContext("2d");
       if (!ctx) return;
       const { naturalWidth: w, naturalHeight: h } = entry.image;
       const fit = Math.min(size / w, size / h);
       const dw = w * fit;
       const dh = h * fit;
       ctx.clearRect(0, 0, size, size);
       ctx.drawImage(entry.image, (size - dw) / 2, (size - dh) / 2, dw, dh);
       const { gl } = this;
       gl.bindTexture(gl.TEXTURE_2D_ARRAY, this.texture);
       gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
       gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, true);
       gl.texSubImage3D(gl.TEXTURE_2D_ARRAY, 0, 0, 0, layer, size, size, 1, gl.RGBA, gl.UNSIGNED_BYTE, this.scratch);
       const u = dw / size / 2;
       const v = dh / size / 2;
       entry.content = [0.5 - u, 0.5 - v, 0.5 + u, 0.5 + v];
       entry.layer = layer;
       entry.state = "ready";
       if (!entry.loadedAt) entry.loadedAt = performance.now();
       this.mipsDirty = true;
     }
   
     /** Cover-fits a card onto its image's content rect, optionally panned. */
     private coverUv(entry: TextureEntry, width: number, height: number, panX: number, panY: number, out: Float32Array, offset: number) {
       const cardAspect = width / Math.max(1, height);
       let uSpan = 1;
       let vSpan = 1;
       if (cardAspect > entry.aspect) vSpan = entry.aspect / cardAspect;
       else uSpan = cardAspect / entry.aspect;
       const uc = 0.5 + (clamp(panX, -1, 1) * (1 - uSpan)) / 2;
       const vc = 0.5 + (clamp(panY, -1, 1) * (1 - vSpan)) / 2;
       const [u0, v0, u1, v1] = entry.content;
       out[offset] = u0 + (uc - uSpan / 2) * (u1 - u0);
       out[offset + 1] = v0 + (vc - vSpan / 2) * (v1 - v0);
       out[offset + 2] = u0 + (uc + uSpan / 2) * (u1 - u0);
       out[offset + 3] = v0 + (vc + vSpan / 2) * (v1 - v0);
     }
   
     private updateCamera(scene: GalleryScene) {
       const fov = ((scene.fov ?? 30) * Math.PI) / 180;
       const distance = this.cssHeight / 2 / Math.tan(fov / 2);
       const c = scene.camera ?? {};
       const eye = [c.x ?? 0, c.y ?? 0, distance + (c.z ?? 0)];
       lookAt(this.view, eye, [c.targetX ?? 0, c.targetY ?? 0, c.targetZ ?? 0]);
       perspective(this.projection, fov, this.cssWidth / this.cssHeight, Math.max(1, distance * 0.02), distance * 20);
       multiply(this.viewProj, this.projection, this.view);
       invert(this.inverseViewProj, this.viewProj);
     }
   
     /** Draws one frame. Returns true while any image is still fading in. */
     render(cards: readonly GalleryCard[], scene: GalleryScene = {}) {
       const { gl } = this;
       this.frame++;
       this.updateCamera(scene);
       const now = performance.now();
       let fading = false;
   
       // Resolve textures and upload anything that finished decoding.
       const textures: (TextureEntry | null)[] = cards.map((card) => (card.image >= 0 ? this.request(card.image) : null));
       for (const entry of textures) if (entry && entry.state === "decoded") this.upload(entry);
       if (this.mipsDirty) {
         gl.bindTexture(gl.TEXTURE_2D_ARRAY, this.texture);
         gl.generateMipmap(gl.TEXTURE_2D_ARRAY);
         this.mipsDirty = false;
       }
   
       // Back-to-front order by view-space depth.
       while (this.models.length < cards.length) this.models.push(createMat4());
       const order = cards.map((card, i) => {
         compose(this.models[i], card.x, card.y, card.z, card.rotateX ?? 0, card.rotateY ?? 0, card.rotateZ ?? 0, card.scale ?? 1, card.flip ?? 0);
         const depth = this.view[2] * card.x + this.view[6] * card.y + this.view[10] * card.z + this.view[14];
         return { i, depth };
       });
       order.sort((a, b) => a.depth - b.depth);
   
       const reflections = scene.floorY !== undefined ? order.filter(({ i }) => (cards[i].reflection ?? 0) > 0) : [];
       const needed = reflections.length + order.length * 2;
       if (needed > this.capacity) {
         this.capacity = Math.max(needed, this.capacity * 2);
         this.data = new Float32Array(this.capacity * FLOATS);
         gl.bindBuffer(gl.ARRAY_BUFFER, this.instances);
         gl.bufferData(gl.ARRAY_BUFFER, this.data.byteLength, gl.DYNAMIC_DRAW);
       }
   
       let count = 0;
       const write = (i: number, kind: number) => {
         const card = cards[i];
         const entry = textures[i];
         const o = count * FLOATS;
         const d = this.data;
         d.set(this.models[i], o);
         d[o + 16] = card.width;
         d[o + 17] = card.height;
         d[o + 18] = card.radius ?? 12;
         d[o + 19] = card.round ?? 0;
         d[o + 20] = card.opacity ?? 1;
         d[o + 21] = card.dim ?? 0;
         d[o + 22] = card.tone ?? 1;
         d[o + 23] = card.ring ?? 0;
         const ready = entry !== null && entry.state === "ready" && entry.layer >= 0;
         const loaded = ready ? clamp((now - entry.loadedAt) / 320, 0, 1) : 0;
         if (ready && loaded < 1) fading = true;
         d[o + 24] = ready ? entry.layer : -1;
         d[o + 25] = loaded;
         d[o + 26] = card.border ?? 0;
         d[o + 27] = card.shadow ?? 0;
         d[o + 28] = kind;
         d[o + 29] = card.reflection ?? 0;
         d[o + 30] = 0;
         d[o + 31] = 0;
         if (ready) this.coverUv(entry, card.width - (card.border ?? 0) * 2, card.height - (card.border ?? 0) * 2, card.panX ?? 0, card.panY ?? 0, d, o + 32);
         else d.fill(0, o + 32, o + 36);
         const fill = card.fill;
         d[o + 36] = fill ? fill[0] : 0;
         d[o + 37] = fill ? fill[1] : 0;
         d[o + 38] = fill ? fill[2] : 0;
         d[o + 39] = fill ? fill[3] : 0;
         count++;
       };
       for (const { i } of reflections) write(i, KIND_REFLECTION);
       this.picks.length = 0;
       for (const { i } of order) {
         const card = cards[i];
         if ((card.shadow ?? 0) > 0 && (card.opacity ?? 1) > 0) write(i, KIND_SHADOW);
         write(i, KIND_CARD);
         this.picks.push({ id: card.id ?? i, model: this.models[i], width: card.width, height: card.height });
       }
   
       const canvas = gl.canvas as HTMLCanvasElement;
       gl.viewport(0, 0, canvas.width, canvas.height);
       gl.clearColor(0, 0, 0, 0);
       gl.clear(gl.COLOR_BUFFER_BIT);
       if (count) {
         gl.enable(gl.BLEND);
         gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
         gl.useProgram(this.program);
         const u = this.uniforms;
         gl.uniformMatrix4fv(u.u_viewProj, false, this.viewProj);
         gl.uniform1f(u.u_floorY, scene.floorY ?? -1e6);
         gl.uniform1f(u.u_reflectFade, scene.reflectionFade ?? 160);
         gl.uniform1f(u.u_shadowOffset, scene.shadowOffset ?? 14);
         gl.uniform1f(u.u_shadowBlur, scene.shadowBlur ?? 22);
         gl.uniform1f(u.u_shadowOpacity, scene.shadowOpacity ?? 0.28);
         gl.uniform2f(u.u_resolution, canvas.width, canvas.height);
         gl.uniform2f(u.u_edgeFade, scene.edgeFade?.[0] ?? 0, scene.edgeFade?.[1] ?? 0);
         gl.uniform3fv(u.u_placeholder, scene.placeholder ?? [0.94, 0.94, 0.95]);
         gl.uniform3fv(u.u_paper, scene.paper ?? [0.98, 0.97, 0.95]);
         gl.uniform3fv(u.u_ring, scene.ring ?? [0.145, 0.388, 0.922]);
         gl.uniform1i(u.u_images, 0);
         gl.activeTexture(gl.TEXTURE0);
         gl.bindTexture(gl.TEXTURE_2D_ARRAY, this.texture);
         gl.bindBuffer(gl.ARRAY_BUFFER, this.instances);
         gl.bufferSubData(gl.ARRAY_BUFFER, 0, this.data, 0, count * FLOATS);
         gl.bindVertexArray(this.vao);
         gl.drawArraysInstanced(gl.TRIANGLES, 0, 6, count);
         gl.bindVertexArray(null);
       }
       return fading;
     }
   
     /** The front-most card under a point in CSS px (relative to the canvas), or null. */
     pick(x: number, y: number): PickResult | null {
       const nx = (x / this.cssWidth) * 2 - 1;
       const ny = 1 - (y / this.cssHeight) * 2;
       const near = transform(this.inverseViewProj, nx, ny, -1);
       const far = transform(this.inverseViewProj, nx, ny, 1);
       const origin = [near[0] / near[3], near[1] / near[3], near[2] / near[3]];
       const end = [far[0] / far[3], far[1] / far[3], far[2] / far[3]];
       const inverse = createMat4();
       for (let k = this.picks.length - 1; k >= 0; k--) {
         const { id, model, width, height } = this.picks[k];
         if (!invert(inverse, model)) continue;
         const o = transform(inverse, origin[0], origin[1], origin[2]);
         const e = transform(inverse, end[0], end[1], end[2]);
         const dz = e[2] - o[2];
         if (Math.abs(dz) < 1e-9) continue;
         const t = -o[2] / dz;
         if (t < 0 || t > 1) continue;
         const px = o[0] + (e[0] - o[0]) * t;
         const py = o[1] + (e[1] - o[1]) * t;
         if (Math.abs(px) <= width / 2 && Math.abs(py) <= height / 2) return { id, u: px / width + 0.5, v: py / height + 0.5 };
       }
       return null;
     }
   
     /** World point → CSS px relative to the canvas (for positioning DOM overlays). */
     project(x: number, y: number, z: number) {
       const [cx, cy, , cw] = transform(this.viewProj, x, y, z);
       return { x: ((cx / cw) * 0.5 + 0.5) * this.cssWidth, y: (0.5 - (cy / cw) * 0.5) * this.cssHeight, visible: cw > 0 };
     }
   
     /** True once the image at `index` is on the GPU. */
     isLoaded(index: number) {
       const src = this.images[index];
       return src ? this.entries.get(src)?.state === "ready" : false;
     }
   
     destroy() {
       const { gl } = this;
       gl.deleteBuffer(this.quad);
       gl.deleteBuffer(this.instances);
       gl.deleteVertexArray(this.vao);
       gl.deleteTexture(this.texture);
       gl.deleteProgram(this.program);
       this.entries.clear();
       gl.getExtension("WEBGL_lose_context")?.loseContext();
     }
   }

   Show all 655 lines

   lib/gallery/types.ts

   import type { CSSProperties, Ref } from "react";
   
   /** One image in a gallery. */
   export interface GalleryItem {
     src: string;
     /** Describes the image for screen readers and the fallback list. */
     alt: string;
     title?: string;
     subtitle?: string;
     /** Optional link, e.g. opened by onSelect. */
     href?: string;
   }
   
   /** Imperative handle shared by every gallery. */
   export interface GalleryHandle {
     next: () => void;
     previous: () => void;
     goTo: (index: number) => void;
   }
   
   /**
    * Props every gallery accepts. Each gallery copies these into its own props interface (with the
    * JSDoc and defaults that fit it) so its props table stays complete.
    */
   export interface GallerySharedProps {
     items: GalleryItem[];
     startIndex?: number;
     autoplay?: boolean;
     interval?: number;
     pauseOnHover?: boolean;
     draggable?: boolean;
     wheel?: boolean;
     captions?: boolean;
     controls?: boolean;
     backgroundColor?: string;
     paused?: boolean;
     dpr?: number;
     ariaLabel?: string;
     className?: string;
     style?: CSSProperties;
     onIndexChange?: (index: number) => void;
     onSelect?: (item: GalleryItem, index: number) => void;
     ref?: Ref<GalleryHandle>;
   }

   Show all 44 lines

   lib/gallery/use-gallery-input.ts

   import { useEffect, useMemo, useRef, useState } from "react";
   import { clamp, wrap } from "@/lib/gallery/math";
   
   export interface DragMove {
     /** Pointer movement since the previous move event, CSS px. */
     dx: number;
     dy: number;
     /** Pointer and drag-start positions relative to the element. */
     x: number;
     y: number;
     startX: number;
     startY: number;
     width: number;
     height: number;
   }
   
   export interface UseGalleryInputOptions {
     /** Number of items. */
     count: number;
     /** Wrap past the first and last item. @default false */
     loop?: boolean;
     /** Index shown first. @default 0 */
     startIndex?: number;
     /** Pointer drag with momentum. @default true */
     draggable?: boolean;
     /** One item per wheel notch. At the first or last item the page scrolls instead. @default true */
     wheel?: boolean;
     /** ← → (or ↑ ↓ on the y axis), Home, End, Enter, Escape and Space. @default true */
     keyboard?: boolean;
     /** Settle on the nearest item after a drag or throw. @default true */
     snap?: boolean;
     /** Seconds of glide a throw carries; 0 stops dead. @default 0.35 */
     inertia?: number;
     /** Drag and arrow-key axis. @default "x" */
     axis?: "x" | "y";
     /** Pixels of drag that move one item, or a function of the element's size. @default 200 */
     dragDistance?: number | ((width: number, height: number) => number);
     /** Custom drag mapping (e.g. turning a wheel around its center): returns the change in position, in items. */
     dragDelta?: (move: DragMove) => number;
     /** Step to the next item every `interval`. @default false */
     autoplay?: boolean;
     /** Autoplay interval in ms. @default 4000 */
     interval?: number;
     /** Pause autoplay while hovered. @default true */
     pauseOnHover?: boolean;
     /** Stops autoplay (input still works). @default false */
     paused?: boolean;
     /** Space toggles pause even without step autoplay, for galleries with continuous motion (drift, spin, streams). @default false */
     pausable?: boolean;
     /** Request a frame on every pointer move, e.g. for hover picking. @default false */
     trackPointer?: boolean;
     onIndexChange?: (index: number) => void;
     /** Enter on the gallery itself (not on a button inside it). */
     onSelect?: (index: number) => void;
     onEscape?: () => void;
     /** A press without a drag, in element coordinates. */
     onTap?: (point: { x: number; y: number }, input: Omit<GalleryInput, "index" | "autoplaying" | "userPaused">) => void;
     /** Called whenever the position changes so a renderer can draw. */
     invalidate?: () => void;
   }
   
   export interface GalleryInput {
     /** Pass as the gallery root's `ref`: the root receives pointer, wheel and key events. */
     bind: (element: HTMLElement | null) => void | (() => void);
     /** Active item (nearest to the current position). */
     index: number;
     /** Autoplay is on and not paused by the user or the `paused` prop. */
     autoplaying: boolean;
     /** The user paused motion (Space or `togglePause`). */
     userPaused: boolean;
     /** Current position in items (fractional while moving; unbounded when looping). */
     position: () => number;
     /** Active item right now (use in event handlers; `index` is the rendered value). */
     activeIndex: () => number;
     /** Velocity in items per second. */
     velocity: () => number;
     /** Advances the physics by dt seconds. Returns true while still moving. */
     update: (dt: number) => boolean;
     /** Moves the position by `delta` items with no spring (continuous drift). Ignored while a gesture or snap is in progress. */
     drift: (delta: number) => void;
     /** Drags from another control (e.g. a ruler): moves by `delta` items like a pointer drag. Finish with `scrubEnd()`. */
     scrub: (delta: number) => void;
     /** Ends a scrub: momentum, snapping and the quick-flick rule apply as for a drag. */
     scrubEnd: () => void;
     next: () => void;
     previous: () => void;
     goTo: (index: number, options?: { instant?: boolean }) => void;
     dragging: () => boolean;
     hovering: () => boolean;
     /** Last pointer position over the element. */
     pointer: () => { x: number; y: number; inside: boolean };
     /** True when autoplay or drift may run right now (not hovered, dragged, held, hidden or reduced). */
     canAutoplay: () => boolean;
     /** Holds autoplay for a reason, e.g. while an item is open. */
     hold: (reason: string, active: boolean) => void;
     togglePause: () => void;
   }
   
   const reducedMotion = () => typeof window !== "undefined" && window.matchMedia("(prefers-reduced-motion: reduce)").matches;
   
   /**
    * One input model for every gallery: a continuous position (in items) driven by pointer drag with
    * momentum and snapping, wheel notches, the keyboard and autoplay. Physics runs in `update(dt)`,
    * which the gallery's render loop calls each frame, so nothing re-renders React mid-gesture.
    */
   export function useGalleryInput(options: UseGalleryInputOptions): GalleryInput {
     const latest = useRef(options);
     const startIndex = clamp(Math.round(options.startIndex ?? 0), 0, Math.max(0, options.count - 1));
     const [index, setIndex] = useState(startIndex);
     const [userPaused, setUserPaused] = useState(false);
     const restartAutoplay = useRef(() => {});
     const state = useRef({
       p: startIndex,
       raw: startIndex,
       v: 0,
       target: null as number | null,
       dragging: false,
       pending: false,
       pointerId: -1,
       startX: 0,
       startY: 0,
       startP: 0,
       downT: 0,
       lastX: 0,
       lastY: 0,
       samples: [] as { t: number; p: number }[],
       hovering: false,
       inside: false,
       px: 0,
       py: 0,
       wheelAcc: 0,
       wheelAt: 0,
       lastIndex: startIndex,
       suppressClick: false,
       holds: new Set<string>(),
       userPaused: false,
     });
   
     useEffect(() => {
       latest.current = options;
     });
   
     const api = useMemo(() => {
       const st = () => state.current;
       const max = () => Math.max(0, latest.current.count - 1);
       const kick = () => latest.current.invalidate?.();
   
       const sync = () => {
         const s = st();
         const { count, loop } = latest.current;
         if (count <= 0) return;
         const i = loop ? wrap(Math.round(s.p), count) : clamp(Math.round(s.p), 0, count - 1);
         if (i === s.lastIndex) return;
         s.lastIndex = i;
         setIndex(i);
         latest.current.onIndexChange?.(i);
       };
   
       const moveTo = (position: number, instant = false) => {
         const s = st();
         s.dragging = false;
         s.target = position;
         if (instant || reducedMotion()) {
           s.p = s.raw = position;
           s.v = 0;
           s.target = null;
         }
         sync();
         kick();
         restartAutoplay.current();
       };
   
       const goTo = (target: number, opts?: { instant?: boolean }) => {
         const { count, loop } = latest.current;
         if (!count) return;
         const s = st();
         const base = Math.round(s.target ?? s.p);
         if (loop) {
           let delta = wrap(Math.round(target) - wrap(base, count), count);
           if (delta > count / 2) delta -= count;
           moveTo(base + delta, opts?.instant);
         } else {
           moveTo(clamp(Math.round(target), 0, max()), opts?.instant);
         }
       };
   
       const step = (direction: number, cycle = false) => {
         const s = st();
         const base = Math.round(s.target ?? s.p);
         if (latest.current.loop) return moveTo(base + direction);
         const next = base + direction;
         if (cycle && next > max()) return moveTo(0);
         moveTo(clamp(next, 0, max()));
       };
   
       const canAutoplay = () => {
         const o = latest.current;
         const s = st();
         return (
           o.count > 1 &&
           !o.paused &&
           !s.userPaused &&
           !reducedMotion() &&
           !((o.pauseOnHover ?? true) && s.hovering) &&
           !s.dragging &&
           s.holds.size === 0 &&
           document.visibilityState === "visible"
         );
       };
   
       const update = (dt: number) => {
         const s = st();
         if (s.dragging) return true;
         if (s.target !== null) {
           if (reducedMotion()) {
             s.p = s.raw = s.target;
             s.v = 0;
             s.target = null;
             sync();
             return false;
           }
           // Critically damped spring, sub-stepped for stability on slow frames.
           const omega = 11;
           let remaining = dt;
           while (remaining > 0) {
             const h = Math.min(remaining, 1 / 120);
             s.v += (-omega * omega * (s.p - s.target) - 2 * omega * s.v) * h;
             s.p += s.v * h;
             remaining -= h;
           }
           if (Math.abs(s.p - s.target) < 0.0008 && Math.abs(s.v) < 0.01) {
             s.p = s.target;
             s.v = 0;
             s.target = null;
           }
           s.raw = s.p;
           sync();
           return s.target !== null;
         }
         if (s.v !== 0) {
           s.v *= Math.exp(-dt / Math.max(0.05, latest.current.inertia ?? 0.35));
           s.p += s.v * dt;
           if (!latest.current.loop && (s.p < 0 || s.p > max())) s.target = clamp(s.p, 0, max());
           if (Math.abs(s.v) < 0.02) s.v = 0;
           s.raw = s.p;
           sync();
           return s.v !== 0 || s.target !== null;
         }
         return false;
       };
   
       const release = () => {
         const s = st();
         s.dragging = false;
         const now = performance.now();
         const samples = s.samples;
         const lastSample = samples[samples.length - 1];
         let v = 0;
         // Only a pointer still moving at release throws. Use the last 150ms, but always at least the
         // last two samples: slow devices and coalesced events can space moves 80ms or more apart.
         if (lastSample && now - lastSample.t < 100) {
           let first = samples.find((sample) => now - sample.t < 150) ?? lastSample;
           if (first === lastSample && samples.length >= 2) first = samples[samples.length - 2];
           if (first !== lastSample) v = (lastSample.p - first.p) / Math.max(0.016, (lastSample.t - first.t) / 1000);
         }
         v = clamp(v, -30, 30);
         const { snap = true, inertia = 0.35, loop } = latest.current;
         if (snap) {
           let target = Math.round(s.p + v * inertia);
           const from = Math.round(s.startP);
           // A quick flick always moves at least one item: either it was still moving fast at release,
           // or the whole press was short and travelled a noticeable distance.
           const travel = s.p - s.startP;
           const quick = now - s.downT < 320 && Math.abs(travel) > 0.06;
           if (target === from && (Math.abs(v) > 0.6 || quick)) target = from + Math.sign(Math.abs(v) > 0.6 ? v : travel);
           s.target = loop ? target : clamp(target, 0, max());
         } else if (!loop && (s.p < 0 || s.p > max())) {
           s.target = clamp(s.p, 0, max());
         }
         s.v = v;
         if (reducedMotion()) {
           s.p = s.raw = s.target ?? s.p;
           s.v = 0;
           s.target = null;
         }
         sync();
         kick();
         restartAutoplay.current();
       };
   
       const togglePause = () => {
         const s = st();
         s.userPaused = !s.userPaused;
         setUserPaused(s.userPaused);
         restartAutoplay.current();
       };
   
       const bind = (element: HTMLElement | null) => {
         if (!element) return;
         const s = st();
         const local = (event: { clientX: number; clientY: number }) => {
           const rect = element.getBoundingClientRect();
           return { x: event.clientX - rect.left, y: event.clientY - rect.top, width: rect.width, height: rect.height };
         };
         const onDown = (event: PointerEvent) => {
           if (event.pointerType === "mouse" && event.button !== 0) return;
           if ((event.target as Element | null)?.closest?.("[data-gallery-control]")) return;
           const point = local(event);
           s.pending = true;
           s.pointerId = event.pointerId;
           s.startX = s.lastX = point.x;
           s.startY = s.lastY = point.y;
           s.downT = performance.now();
         };
         const onMove = (event: PointerEvent) => {
           const point = local(event);
           s.px = point.x;
           s.py = point.y;
           s.inside = true;
           if (latest.current.trackPointer) kick();
           if (!s.pending || event.pointerId !== s.pointerId) return;
           if (!s.dragging) {
             if (!(latest.current.draggable ?? true)) return;
             if (Math.hypot(point.x - s.startX, point.y - s.startY) < 6) return;
             // Capture only once the pointer really moves, so clicks on links and buttons still land.
             s.dragging = true;
             s.target = null;
             s.v = 0;
             s.startP = s.raw = s.p;
             // Measure from the press: a fast flick may arrive as a single coalesced move event, and its
             // full distance (and speed) must still count.
             s.samples = [{ t: s.downT, p: s.p }];
             s.lastX = s.startX;
             s.lastY = s.startY;
             try {
               element.setPointerCapture(event.pointerId);
             } catch {}
           }
           const move: DragMove = { dx: point.x - s.lastX, dy: point.y - s.lastY, x: point.x, y: point.y, startX: s.startX, startY: s.startY, width: point.width, height: point.height };
           const o = latest.current;
           let delta: number;
           if (o.dragDelta) delta = o.dragDelta(move);
           else {
             const distance = typeof o.dragDistance === "function" ? o.dragDistance(point.width, point.height) : (o.dragDistance ?? 200);
             delta = -((o.axis ?? "x") === "y" ? move.dy : move.dx) / Math.max(1, distance);
           }
           s.raw += delta;
           s.p = rubber(s.raw);
           s.lastX = point.x;
           s.lastY = point.y;
           s.samples.push({ t: performance.now(), p: s.p });
           if (s.samples.length > 12) s.samples.shift();
           sync();
           kick();
         };
         const onUp = (event: PointerEvent) => {
           if (event.pointerId !== s.pointerId) return;
           const wasDragging = s.dragging;
           s.pending = false;
           s.pointerId = -1;
           if (wasDragging) {
             s.suppressClick = true;
             window.setTimeout(() => {
               s.suppressClick = false;
             }, 0);
             try {
               element.releasePointerCapture(event.pointerId);
             } catch {}
             release();
           } else if (event.type === "pointerup") {
             latest.current.onTap?.(local(event), controls);
           }
         };
         const onClickCapture = (event: MouseEvent) => {
           if (!s.suppressClick) return;
           event.preventDefault();
           event.stopPropagation();
         };
         const onEnter = (event: PointerEvent) => {
           if (event.pointerType !== "mouse") return;
           s.hovering = true;
           kick();
         };
         const onLeave = () => {
           s.hovering = false;
           s.inside = false;
           kick();
           restartAutoplay.current();
         };
         const onWheel = (event: WheelEvent) => {
           if (!(latest.current.wheel ?? true)) return;
           const scale = event.deltaMode === 1 ? 16 : event.deltaMode === 2 ? element.clientHeight : 1;
           const dx = event.deltaX * scale;
           const dy = event.deltaY * scale;
           const delta = Math.abs(dx) > Math.abs(dy) ? dx : dy;
           if (!delta) return;
           const direction = Math.sign(delta);
           const base = Math.round(s.target ?? s.p);
           // At either end, let the page scroll instead of trapping the wheel.
           if (!latest.current.loop && ((direction < 0 && base <= 0) || (direction > 0 && base >= max()))) {
             s.wheelAcc = 0;
             return;
           }
           event.preventDefault();
           s.wheelAcc += delta;
           const now = performance.now();
           const notch = event.deltaMode !== 0 || Math.abs(delta) >= 50;
           if ((notch || Math.abs(s.wheelAcc) >= 60) && now - s.wheelAt > 110) {
             s.wheelAt = now;
             s.wheelAcc = 0;
             step(direction);
           }
         };
         const onKeyDown = (event: KeyboardEvent) => {
           const o = latest.current;
           if (!(o.keyboard ?? true)) return;
           const target = event.target as HTMLElement;
           if (target.closest("input, textarea, select, [contenteditable='true']")) return;
           const vertical = (o.axis ?? "x") === "y";
           if (event.key === (vertical ? "ArrowDown" : "ArrowRight")) {
             event.preventDefault();
             step(1);
           } else if (event.key === (vertical ? "ArrowUp" : "ArrowLeft")) {
             event.preventDefault();
             step(-1);
           } else if (event.key === "Home") {
             event.preventDefault();
             goTo(0);
           } else if (event.key === "End") {
             event.preventDefault();
             goTo(max());
           } else if (event.key === "Enter") {
             // Buttons and links inside the gallery handle Enter themselves.
             if (target !== element && target.closest("button, a")) return;
             event.preventDefault();
             o.onSelect?.(s.lastIndex);
           } else if (event.key === "Escape") {
             o.onEscape?.();
           } else if (event.key === " " && (o.autoplay || o.pausable) && !target.closest("[data-gallery-control]")) {
             event.preventDefault();
             togglePause();
           }
         };
         const onKeyUp = (event: KeyboardEvent) => {
           const o = latest.current;
           if (event.key === " " && (o.autoplay || o.pausable) && (o.keyboard ?? true) && !(event.target as HTMLElement).closest("[data-gallery-control]")) event.preventDefault();
         };
         const onDragStart = (event: Event) => event.preventDefault();
   
         element.addEventListener("pointerdown", onDown);
         element.addEventListener("pointermove", onMove);
         element.addEventListener("pointerup", onUp);
         element.addEventListener("pointercancel", onUp);
         element.addEventListener("pointerenter", onEnter);
         element.addEventListener("pointerleave", onLeave);
         element.addEventListener("click", onClickCapture, true);
         element.addEventListener("wheel", onWheel, { passive: false });
         element.addEventListener("keydown", onKeyDown);
         element.addEventListener("keyup", onKeyUp);
         element.addEventListener("dragstart", onDragStart);
         return () => {
           element.removeEventListener("pointerdown", onDown);
           element.removeEventListener("pointermove", onMove);
           element.removeEventListener("pointerup", onUp);
           element.removeEventListener("pointercancel", onUp);
           element.removeEventListener("pointerenter", onEnter);
           element.removeEventListener("pointerleave", onLeave);
           element.removeEventListener("click", onClickCapture, true);
           element.removeEventListener("wheel", onWheel);
           element.removeEventListener("keydown", onKeyDown);
           element.removeEventListener("keyup", onKeyUp);
           element.removeEventListener("dragstart", onDragStart);
         };
       };
   
       const rubber = (value: number) => {
         if (latest.current.loop) return value;
         const limit = max();
         if (value < 0) return value * 0.35;
         if (value > limit) return limit + (value - limit) * 0.35;
         return value;
       };
   
       const scrub = (delta: number) => {
         const s = st();
         const now = performance.now();
         if (!s.dragging) {
           s.dragging = true;
           s.target = null;
           s.v = 0;
           s.startP = s.raw = s.p;
           s.downT = now;
           s.samples = [{ t: now, p: s.p }];
         }
         s.raw += delta;
         s.p = rubber(s.raw);
         s.samples.push({ t: now, p: s.p });
         if (s.samples.length > 12) s.samples.shift();
         sync();
         kick();
       };
   
       const scrubEnd = () => {
         if (st().dragging) release();
       };
   
       const drift = (delta: number) => {
         const s = st();
         if (s.dragging || s.pending || s.target !== null || s.v !== 0 || !delta) return;
         s.p = latest.current.loop ? s.p + delta : clamp(s.p + delta, 0, max());
         s.raw = s.p;
         sync();
       };
   
       const controls: Omit<GalleryInput, "index" | "autoplaying" | "userPaused"> = {
         bind,
         position: () => st().p,
         activeIndex: () => st().lastIndex,
         velocity: () => st().v,
         update,
         drift,
         scrub,
         scrubEnd,
         next: () => step(1),
         previous: () => step(-1),
         goTo,
         dragging: () => st().dragging,
         hovering: () => st().hovering,
         pointer: () => ({ x: st().px, y: st().py, inside: st().inside }),
         canAutoplay,
         hold: (reason: string, active: boolean) => {
           const s = st();
           if (active) s.holds.add(reason);
           else s.holds.delete(reason);
           restartAutoplay.current();
           kick();
         },
         togglePause,
       };
       // Autoplay cycles back to the start at the end of a non-looping gallery.
       return { controls, autoStep: () => step(1, true) };
     }, []);
   
     const { autoplay, interval } = options;
     useEffect(() => {
       if (!autoplay) return;
       const wait = Math.max(800, interval ?? 4000);
       let timer = 0;
       const tick = () => {
         timer = window.setTimeout(() => {
           if (api.controls.canAutoplay()) api.autoStep();
           tick();
         }, wait);
       };
       // Any manual move restarts the countdown so autoplay never jumps right after the user acts.
       restartAutoplay.current = () => {
         window.clearTimeout(timer);
         tick();
       };
       tick();
       return () => {
         window.clearTimeout(timer);
         restartAutoplay.current = () => {};
       };
     }, [autoplay, interval, api]);
   
     return { ...api.controls, index, userPaused, autoplaying: Boolean(autoplay) && !options.paused && !userPaused };
   }

   Show all 568 lines

   lib/gallery/use-gallery-renderer.ts

   import { useCallback, useEffect, useRef, useState } from "react";
   import { GalleryRenderer, type GalleryCard, type GalleryScene } from "@/lib/gallery/renderer";
   
   /**
    * - `idle`: not started yet (always the value on the server and the first client render)
    * - `ready`: WebGL is drawing
    * - `fallback`: WebGL2 is unavailable, the shaders failed or the context could not be restored
    */
   export type GalleryStatus = "idle" | "ready" | "fallback";
   
   export interface GalleryFrameState {
     /** Seconds since the renderer started (only advances while frames are drawn). */
     time: number;
     /** Seconds since the previous frame, capped at 0.1. */
     dt: number;
     /** Host size in CSS px. */
     width: number;
     height: number;
     reducedMotion: boolean;
     /**
      * Ambient motion (drift, autoplay) may run. False for all but one gallery preview on a page of
      * gallery cards: the others hold a still poster frame until they become the hovered or most
      * visible card. Input-driven motion always runs.
      */
     ambient: boolean;
     /** Scratch values that persist between frames (e.g. a drift velocity). */
     memory: Record<string, number>;
     renderer: GalleryRenderer;
   }
   
   export interface GalleryFrame {
     cards: readonly GalleryCard[];
     scene?: GalleryScene;
     /** Keep drawing frames. When false the loop sleeps until `invalidate()` is called. */
     animating?: boolean;
   }
   
   export interface UseGalleryRendererOptions {
     /** Image URLs; cards refer to them by index. */
     images: string[];
     /** Builds each frame's cards. Runs inside requestAnimationFrame, so it can read refs freely. */
     frame: (state: GalleryFrameState) => GalleryFrame;
     /** Highest device pixel ratio used (software WebGL is capped at 1). @default 2 */
     dpr?: number;
     /** Texture layer size in px. @default 512 */
     textureSize?: number;
     /** Texture layers kept on the GPU (least recently used are recycled). @default number of distinct images, up to 32 */
     maxTextures?: number;
   }
   
   interface PreviewLease {
     ratio: number;
     hovered: boolean;
     wake: () => void;
   }
   
   // Gallery previews (inside [data-preview-card], e.g. docs gallery cards) share one animation lease.
   const previews = new Set<PreviewLease>();
   let leader: PreviewLease | null = null;
   
   function electLeader() {
     let best: PreviewLease | null = null;
     for (const lease of previews) {
       if (lease.ratio <= 0) continue;
       if (!best || (lease.hovered && !best.hovered) || (lease.hovered === best.hovered && lease.ratio > best.ratio)) best = lease;
     }
     if (best === leader) return;
     const previous = leader;
     leader = best;
     previous?.wake();
     best?.wake();
   }
   
   /**
    * Runs a GalleryRenderer on a canvas the hook creates inside the element you attach `hostRef` to
    * (give it a size and `position: relative` or `absolute`). The loop only runs while the frame
    * reports `animating`, images fade in, or `invalidate()` is called, and never offscreen or in a
    * hidden tab. Context loss is recovered; everything is released on unmount.
    */
   export function useGalleryRenderer<T extends HTMLElement = HTMLDivElement>(options: UseGalleryRendererOptions) {
     const hostRef = useRef<T>(null);
     const rendererRef = useRef<GalleryRenderer | null>(null);
     const [status, setStatus] = useState<GalleryStatus>("idle");
     const latest = useRef(options);
     const wake = useRef<() => void>(() => {});
   
     useEffect(() => {
       latest.current = options;
       wake.current();
     });
   
     /** Requests a frame. Safe to call from any event handler, many times per frame. */
     const invalidate = useCallback(() => wake.current(), []);
   
     useEffect(() => {
       const host = hostRef.current;
       if (!host) return;
       const canvas = document.createElement("canvas");
       canvas.setAttribute("aria-hidden", "true");
       Object.assign(canvas.style, {
         position: "absolute",
         inset: "0",
         width: "100%",
         height: "100%",
         display: "block",
         pointerEvents: "none",
         opacity: "0",
         transition: "opacity 320ms ease-out",
       });
       host.appendChild(canvas);
   
       const reduced = window.matchMedia("(prefers-reduced-motion: reduce)");
       const previewCard = host.closest<HTMLElement>("[data-preview-card]");
       const lease: PreviewLease | null = previewCard ? { ratio: 0, hovered: false, wake: () => wakeUp() } : null;
       const memory: Record<string, number> = {};
       let renderer: GalleryRenderer | null = null;
       let raf = 0;
       let last = 0;
       let clock = 0;
       let inView = false;
       let pageVisible = document.visibilityState === "visible";
       let lost = false;
       let needsResize = true;
       let shown = false;
   
       const resize = () => {
         if (!renderer) return;
         const cap = renderer.software ? 1 : Math.min(latest.current.dpr ?? 2, lease ? 1.5 : Infinity);
         renderer.resize(host.clientWidth, host.clientHeight, Math.min(window.devicePixelRatio || 1, Math.max(0.5, cap)));
         needsResize = false;
       };
   
       const frame = (now: number) => {
         raf = 0;
         if (!renderer || lost) return;
         const dt = last ? Math.min((now - last) / 1000, 0.1) : 1 / 60;
         last = now;
         clock += dt;
         if (needsResize) resize();
         renderer.setImages(latest.current.images);
         const result = latest.current.frame({
           time: clock,
           dt,
           width: host.clientWidth,
           height: host.clientHeight,
           reducedMotion: reduced.matches,
           ambient: !lease || leader === lease,
           memory,
           renderer,
         });
         const fading = renderer.render(result.cards, result.scene);
         if (!shown) {
           shown = true;
           canvas.style.opacity = "1";
         }
         if ((result.animating || fading) && inView && pageVisible) raf = requestAnimationFrame(frame);
         else last = 0;
       };
   
       const wakeUp = () => {
         if (!raf && renderer && !lost && inView && pageVisible) raf = requestAnimationFrame(frame);
       };
   
       const intersection = new IntersectionObserver(
         ([entry]) => {
           inView = entry.isIntersecting;
           if (lease) {
             lease.ratio = entry.isIntersecting ? entry.intersectionRatio : 0;
             electLeader();
           }
           wakeUp();
         },
         { rootMargin: "100px", threshold: [0, 0.25, 0.5, 0.75, 1] },
       );
       const onPreviewEnter = () => {
         if (!lease) return;
         lease.hovered = true;
         electLeader();
       };
       const onPreviewLeave = () => {
         if (!lease) return;
         lease.hovered = false;
         electLeader();
       };
       const resizeObserver = new ResizeObserver(() => {
         needsResize = true;
         wakeUp();
       });
       const onVisibility = () => {
         pageVisible = document.visibilityState === "visible";
         wakeUp();
       };
       const onLost = (event: Event) => {
         event.preventDefault();
         lost = true;
         if (raf) cancelAnimationFrame(raf);
         raf = 0;
       };
       const onRestored = () => {
         if (renderer?.restore()) {
           lost = false;
           needsResize = true;
           wakeUp();
         } else {
           setStatus("fallback");
         }
       };
   
       // Start on the next frame: keeps WebGL setup out of the effect body and off the hydration task.
       const start = requestAnimationFrame(() => {
         const { textureSize = 512, maxTextures, images } = latest.current;
         // Previews are small: smaller textures keep several on one page light on GPU memory.
         renderer = GalleryRenderer.create(canvas, {
           textureSize: lease ? Math.min(textureSize, 256) : textureSize,
           layers: maxTextures ?? Math.min(32, Math.max(1, new Set(images).size)),
         });
         if (!renderer) {
           canvas.remove();
           setStatus("fallback");
           return;
         }
         rendererRef.current = renderer;
         renderer.onImageLoad = wakeUp;
         wake.current = wakeUp;
         canvas.addEventListener("webglcontextlost", onLost);
         canvas.addEventListener("webglcontextrestored", onRestored);
         document.addEventListener("visibilitychange", onVisibility);
         intersection.observe(host);
         resizeObserver.observe(host);
         if (lease && previewCard) {
           previews.add(lease);
           previewCard.addEventListener("pointerenter", onPreviewEnter);
           previewCard.addEventListener("pointerleave", onPreviewLeave);
         }
         setStatus("ready");
       });
   
       return () => {
         cancelAnimationFrame(start);
         if (raf) cancelAnimationFrame(raf);
         wake.current = () => {};
         intersection.disconnect();
         resizeObserver.disconnect();
         document.removeEventListener("visibilitychange", onVisibility);
         canvas.removeEventListener("webglcontextlost", onLost);
         canvas.removeEventListener("webglcontextrestored", onRestored);
         if (lease && previewCard) {
           previews.delete(lease);
           previewCard.removeEventListener("pointerenter", onPreviewEnter);
           previewCard.removeEventListener("pointerleave", onPreviewLeave);
           if (leader === lease) leader = null;
           electLeader();
         }
         renderer?.destroy();
         rendererRef.current = null;
         canvas.remove();
       };
     }, []);
   
     return { hostRef, rendererRef, status, invalidate };
   }

   Show all 261 lines

   lib/gallery/use-gallery.ts

   import { useEffect, useRef } from "react";
   import { useGalleryInput, type GalleryInput, type UseGalleryInputOptions } from "@/lib/gallery/use-gallery-input";
   import { useGalleryRenderer, type GalleryFrame, type GalleryFrameState, type UseGalleryRendererOptions } from "@/lib/gallery/use-gallery-renderer";
   
   export interface UseGalleryOptions extends Omit<UseGalleryInputOptions, "invalidate">, Pick<UseGalleryRendererOptions, "images" | "dpr" | "textureSize" | "maxTextures"> {
     /** Builds each frame from the input state, e.g. card positions from `input.position()`. */
     frame: (state: GalleryFrameState, input: GalleryInput) => GalleryFrame;
   }
   
   /** The renderer and the input hook wired together: input changes request frames, frames read input. */
   export function useGallery<T extends HTMLElement = HTMLDivElement>({ images, dpr, textureSize, maxTextures, frame, ...inputOptions }: UseGalleryOptions) {
     const invalidateRef = useRef(() => {});
     const input = useGalleryInput({ ...inputOptions, invalidate: () => invalidateRef.current() });
     const renderer = useGalleryRenderer<T>({ images, dpr, textureSize, maxTextures, frame: (state) => frame(state, input) });
     const { invalidate } = renderer;
     useEffect(() => {
       invalidateRef.current = invalidate;
     }, [invalidate]);
     // `bind` is returned on its own: pass it straight to the root's ref (the compiler treats whatever
     // feeds a ref prop as a ref, so it must not be read off the input object during render).
     return { ...renderer, bind: input.bind, input };
   }

   Show all 22 lines

   lib/motion.ts

   import type { Transition, Variants } from "motion/react";
   
   /** Durations in seconds. */
   export const duration = {
     instant: 0.1,
     quick: 0.18,
     base: 0.28,
     slow: 0.45,
   } as const;
   
   /** Cubic-bezier curves. */
   export const ease = {
     /** Entering, UI response. */
     out: [0.22, 1, 0.36, 1],
     /** Moving on screen. */
     inOut: [0.65, 0, 0.35, 1],
     /** Sheets and the mobile menu. */
     drawer: [0.32, 0.72, 0, 1],
   } as const;
   
   /** Everyday UI: presses, icon swaps, popovers and modals. Exits run at `exitFactor` of the enter. */
   export const ui = {
     press: { scale: 0.96, duration: 0.12 },
     icon: { type: "spring", duration: 0.3, bounce: 0 },
     popover: { duration: 0.18, ease: ease.out },
     modal: { duration: 0.24, ease: ease.out },
     exitFactor: 0.6,
   } as const;
   
   /** Once-per-visit motion on the landing page: hero letters, the reel and the afterimage. */
   export const kinetic = {
     heroLetter: { duration: 0.6, ease: ease.out },
     /** Delay per letter, eased so the wave slows toward the end. */
     heroStep: 0.035,
     reelSwap: { type: "spring", duration: 0.5, bounce: 0.1 },
     /** Two afterimages: lag in seconds and opacity of each. */
     ghost: { lag: [0.04, 0.09], opacity: [0.14, 0.06] },
   } as const;
   
   /** Spring presets. */
   export const spring = {
     snappy: { type: "spring", stiffness: 500, damping: 30 },
     smooth: { type: "spring", stiffness: 260, damping: 26 },
     bouncy: { type: "spring", stiffness: 300, damping: 15 },
   } as const satisfies Record<string, Transition>;
   
   /** Stagger between siblings, in seconds (0.03–0.06). */
   export const stagger = {
     tight: 0.03,
     base: 0.045,
     loose: 0.06,
   } as const;
   
   /** Blur + fade + y-offset. Falls back to a plain fade under reduced motion. */
   export function enterVariants(reduceMotion?: boolean | null, y = 8): Variants {
     if (reduceMotion) {
       return {
         hidden: { opacity: 0 },
         visible: { opacity: 1, transition: { duration: duration.base } },
         exit: { opacity: 0, transition: { duration: duration.quick } },
       };
     }
     return {
       hidden: { opacity: 0, y, filter: "blur(4px)" },
       visible: {
         opacity: 1,
         y: 0,
         filter: "blur(0px)",
         transition: { duration: duration.base, ease: ease.out },
       },
       exit: {
         opacity: 0,
         y: -y / 2,
         filter: "blur(4px)",
         transition: { duration: duration.quick, ease: ease.out },
       },
     };
   }
   
   /** Scale 0.96 → 1 for popovers, menus and dialogs. */
   export function overlayVariants(reduceMotion?: boolean | null): Variants {
     if (reduceMotion) {
       return {
         hidden: { opacity: 0 },
         visible: { opacity: 1, transition: { duration: duration.quick } },
         exit: { opacity: 0, transition: { duration: duration.instant } },
       };
     }
     return {
       hidden: { opacity: 0, scale: 0.96, filter: "blur(2px)" },
       visible: {
         opacity: 1,
         scale: 1,
         filter: "blur(0px)",
         transition: { duration: duration.quick, ease: ease.out },
       },
       exit: {
         opacity: 0,
         scale: 0.96,
         filter: "blur(2px)",
         transition: { duration: duration.instant + 0.02, ease: ease.out },
       },
     };
   }
   
   /** Parent variants that stagger their children in. */
   export function staggerVariants(gap: number = stagger.base, delayChildren = 0): Variants {
     return {
       hidden: {},
       visible: { transition: { staggerChildren: gap, delayChildren } },
       exit: { transition: { staggerChildren: gap / 2, staggerDirection: -1 } },
     };
   }

   Show all 113 lines

3. Copy the source

   components/ui/sleeve-rail/sleeve-rail.tsx

   "use client";
   
   import { useCallback, useEffect, useImperativeHandle, useMemo, useRef, useState, type CSSProperties, type PointerEvent, type Ref } from "react";
   import { ChevronLeft, ChevronRight, Pause, Play } from "lucide-react";
   import { cn } from "@/lib/utils";
   import { GalleryA11y } from "@/lib/gallery/gallery-a11y";
   import { GalleryCaption, chromeScheme } from "@/lib/gallery/gallery-chrome";
   import { GalleryFallback } from "@/lib/gallery/gallery-fallback";
   import { clamp, smoothstep } from "@/lib/gallery/math";
   import type { GalleryCard } from "@/lib/gallery/renderer";
   import type { GalleryHandle, GalleryItem } from "@/lib/gallery/types";
   import { useGallery } from "@/lib/gallery/use-gallery";
   
   export interface SleeveRailHandle extends GalleryHandle {
     /** Slides the focused sleeve's record out and spins it. */
     play: () => void;
     /** Slides the record back into its sleeve. */
     stop: () => void;
   }
   
   export interface SleeveRailProps {
     /** Albums: the image is the sleeve artwork (square works best), title and subtitle the album and artist. */
     items: GalleryItem[];
     /** Sleeve focused first. @default 0 */
     startIndex?: number;
     /** Step to the next sleeve every `interval` (cycles back to the first). Pauses while a record plays. @default false */
     autoplay?: boolean;
     /** Milliseconds between autoplay steps. @default 4000 */
     interval?: number;
     /** Pause autoplay while hovered. @default true */
     pauseOnHover?: boolean;
     /** Drag or throw the rail. @default true */
     draggable?: boolean;
     /** One sleeve per wheel notch. @default true */
     wheel?: boolean;
     /** Title and artist of the focused sleeve, sliding with the rail. @default true */
     captions?: boolean;
     /** The ruler under the rail: a tick per sleeve, a play button at its center and arrows at its ends. @default true */
     controls?: boolean;
     /** Tilt per step outward, like a hand of cards, in degrees. @default 5 */
     fanAngle?: number;
     /** How far neighbours turn away from the viewer, in degrees. @default 40 */
     turnAngle?: number;
     /** How far neighbours recede, px. @default 170 */
     depth?: number;
     /** Distance from the focused sleeve to its first neighbour, in sleeve widths. @default 0.62 */
     spread?: number;
     /** How much tighter the outer sleeves pack, 0–0.95. @default 0.6 */
     packing?: number;
     /** Sleeves visible on each side, 1–5. @default 3 */
     visibleSide?: number;
     /** Sleeve corner radius, px. @default 6 */
     radius?: number;
     /** How much outer sleeves darken, 0–1. @default 0.25 */
     dim?: number;
     /** Drop shadow strength, 0–1. @default 0.8 */
     shadow?: number;
     /** Show the vinyl record (peeks on hover, slides out to play). @default true */
     record?: boolean;
     /** Vinyl color. @default "#121212" */
     recordColor?: string;
     /** Spin speed while playing. @default 33.3 */
     rpm?: number;
     /** Play button and active tick color. "auto" picks the most vivid color of the focused artwork and adjusts it for contrast. @default "auto" */
     accentColor?: string;
     /** Background color; captions and controls switch to light text on dark colors. @default "transparent" */
     backgroundColor?: string;
     /** Stops autoplay and spinning (input still works). @default false */
     paused?: boolean;
     /** Highest device pixel ratio rendered. @default 2 */
     dpr?: number;
     /** Accessible name of the rail. @default "Albums" */
     ariaLabel?: string;
     /** Classes for the root, which fills its parent (at least 420px tall). */
     className?: string;
     /** Inline styles for the root. */
     style?: CSSProperties;
     /** Fires when the focused sleeve changes. */
     onIndexChange?: (index: number) => void;
     /** Fires when the focused sleeve is clicked or Enter is pressed (the record starts playing). */
     onSelect?: (item: GalleryItem, index: number) => void;
     /** Fires when a record starts or stops playing. */
     onPlayChange?: (index: number, playing: boolean) => void;
     /** Imperative `next()`, `previous()`, `goTo(index)`, `play()` and `stop()`. */
     ref?: Ref<SleeveRailHandle>;
   }
   
   const TICK = 14;
   const RECORD_ID = -2;
   const DEFAULT_ACCENT = "var(--primary)";
   const toRad = (deg: number) => (deg * Math.PI) / 180;
   
   /** A vinyl record (grooves, track gaps, rim) drawn once to a data URL. */
   function vinylTexture(color: string) {
     const size = 512;
     const canvas = document.createElement("canvas");
     canvas.width = canvas.height = size;
     const ctx = canvas.getContext("2d");
     if (!ctx) return "";
     const r = size / 2;
     ctx.fillStyle = color;
     ctx.beginPath();
     ctx.arc(r, r, r - 1, 0, Math.PI * 2);
     ctx.fill();
     for (let g = r * 0.4; g < r * 0.965; g += 1.6) {
       const gap = (g > r * 0.62 && g < r * 0.635) || (g > r * 0.79 && g < r * 0.805);
       ctx.strokeStyle = gap ? "rgba(0,0,0,0.4)" : `rgba(255,255,255,${(0.025 + ((g * 7.13) % 1) * 0.035).toFixed(3)})`;
       ctx.lineWidth = gap ? 2 : 0.8;
       ctx.beginPath();
       ctx.arc(r, r, g, 0, Math.PI * 2);
       ctx.stroke();
     }
     ctx.strokeStyle = "rgba(255,255,255,0.1)";
     ctx.lineWidth = 2;
     ctx.beginPath();
     ctx.arc(r, r, r - 2, 0, Math.PI * 2);
     ctx.stroke();
     return canvas.toDataURL("image/png");
   }
   
   /** Two soft highlight lobes. Drawn over the record without spinning, so the light stays put. */
   function sheenTexture() {
     const size = 256;
     const canvas = document.createElement("canvas");
     canvas.width = canvas.height = size;
     const ctx = canvas.getContext("2d");
     if (!ctx || !("createConicGradient" in ctx)) return "";
     const gradient = ctx.createConicGradient(-Math.PI / 4, size / 2, size / 2);
     for (const [stop, alpha] of [[0, 0], [0.08, 0.2], [0.18, 0], [0.5, 0], [0.58, 0.14], [0.68, 0], [1, 0]] as const) gradient.addColorStop(stop, `rgba(255,255,255,${alpha})`);
     ctx.fillStyle = gradient;
     ctx.beginPath();
     ctx.arc(size / 2, size / 2, size / 2 - 1, 0, Math.PI * 2);
     ctx.fill();
     return canvas.toDataURL("image/png");
   }
   
   const luminance = ([r, g, b]: number[]) => {
     const [lr, lg, lb] = [r, g, b].map((c) => {
       const s = c / 255;
       return s <= 0.04045 ? s / 12.92 : ((s + 0.055) / 1.055) ** 2.4;
     });
     return 0.2126 * lr + 0.7152 * lg + 0.0722 * lb;
   };
   const contrast = (a: number[], b: number[]) => {
     const [hi, lo] = [luminance(a), luminance(b)].sort((x, y) => y - x);
     return (hi + 0.05) / (lo + 0.05);
   };
   
   const accentCache = new Map<string, string>();
   
   /** The most vivid color in an image, darkened or lightened until it reads at 3:1 against the background. */
   function vividAccent(image: HTMLImageElement, dark: boolean) {
     const size = 24;
     const canvas = document.createElement("canvas");
     canvas.width = canvas.height = size;
     const ctx = canvas.getContext("2d", { willReadFrequently: true });
     if (!ctx) return null;
     ctx.drawImage(image, 0, 0, size, size);
     const data = ctx.getImageData(0, 0, size, size).data;
     let best: number[] | null = null;
     let bestScore = -1;
     for (let i = 0; i < data.length; i += 4) {
       const r = data[i];
       const g = data[i + 1];
       const b = data[i + 2];
       const max = Math.max(r, g, b);
       const min = Math.min(r, g, b);
       const value = max / 255;
       const saturation = max ? (max - min) / max : 0;
       const score = saturation * (1 - Math.abs(value - 0.7));
       if (score > bestScore) {
         bestScore = score;
         best = [r, g, b];
       }
     }
     if (!best || bestScore < 0.12) return null;
     const against = dark ? [12, 12, 14] : [255, 255, 255];
     let color = best;
     for (let step = 0; step < 24 && contrast(color, against) < 3; step++) {
       color = color.map((c) => (dark ? c + (255 - c) * 0.12 : c * 0.88));
     }
     return `rgb(${color.map((c) => Math.round(c)).join(", ")})`;
   }
   
   /**
    * A fanned rail of album sleeves, each with a vinyl record tucked inside. The focused sleeve sits
    * in front; hover lifts its record, click or Enter slides it out to spin. Rendered with the shared
    * WebGL2 gallery engine; a hidden button list carries the accessible gallery.
    */
   export function SleeveRail({
     items,
     startIndex = 0,
     autoplay = false,
     interval = 4000,
     pauseOnHover = true,
     draggable = true,
     wheel = true,
     captions = true,
     controls = true,
     fanAngle = 5,
     turnAngle = 40,
     depth = 170,
     spread = 0.62,
     packing = 0.6,
     visibleSide = 3,
     radius = 6,
     dim = 0.25,
     shadow = 0.8,
     record = true,
     recordColor = "#121212",
     rpm = 33.3,
     accentColor = "auto",
     backgroundColor = "transparent",
     paused = false,
     dpr = 2,
     ariaLabel = "Albums",
     className,
     style,
     onIndexChange,
     onSelect,
     onPlayChange,
     ref,
   }: SleeveRailProps) {
     const count = items.length;
     const [playing, setPlaying] = useState(false);
     const [autoAccent, setAutoAccent] = useState<{ src: string; color: string } | null>(null);
     const ticks = useRef<HTMLDivElement>(null);
     const scrubbing = useRef<{ id: number; x: number; moved: boolean } | null>(null);
     const scheme = chromeScheme(backgroundColor);
   
     // Generated textures (client only; the server never renders the canvas).
     const vinyl = useMemo(() => (record && typeof document !== "undefined" ? vinylTexture(recordColor) : ""), [record, recordColor]);
     const sheen = useMemo(() => (record && typeof document !== "undefined" ? sheenTexture() : ""), [record]);
     const images = useMemo(() => [...items.map((item) => item.src), vinyl, sheen], [items, vinyl, sheen]);
     const vinylIndex = count;
     const sheenIndex = count + 1;
     const chromeHeight = (captions ? 44 : 0) + (controls ? 52 : 0);
   
     const setPlay = useCallback(
       (next: boolean, index: number) => {
         if (next === playing) return;
         setPlaying(next);
         onPlayChange?.(index, next);
       },
       [playing, onPlayChange],
     );
   
     const { hostRef, bind, status, input, rendererRef } = useGallery({
       images,
       count,
       startIndex,
       draggable,
       wheel,
       autoplay,
       interval,
       pauseOnHover,
       paused,
       dpr,
       trackPointer: record,
       dragDistance: (width, height) => Math.min((height - chromeHeight) * (record ? 0.46 : 0.62), width * 0.34) * spread,
       onIndexChange: (index) => {
         if (playing) setPlay(false, input.index);
         onIndexChange?.(index);
       },
       onSelect: (index) => {
         if (!playing) onSelect?.(items[index], index);
         setPlay(!playing, index);
       },
       onEscape: () => setPlay(false, input.index),
       onTap: (point, gallery) => {
         const hit = rendererRef.current?.pick(point.x, point.y);
         if (!hit) return;
         const active = gallery.activeIndex();
         if (hit.id === RECORD_ID || hit.id === active) {
           if (!playing && hit.id === active) onSelect?.(items[active], active);
           setPlay(!playing, active);
         } else gallery.goTo(hit.id);
       },
       frame: ({ dt, width, height, reducedMotion, ambient, memory, renderer }, gallery) => {
         if (memory.ambient !== Number(ambient)) {
           memory.ambient = Number(ambient);
           gallery.hold("ambient", !ambient);
         }
         let moving = gallery.update(dt);
         const position = gallery.position();
         const active = gallery.activeIndex();
         // The ruler's ticks slide with the rail (direct style write: no React render per frame).
         if (ticks.current) ticks.current.style.transform = `translateX(${(-position * TICK).toFixed(2)}px)`;
   
         const size = Math.min(height * (record ? 0.46 : 0.62), width * 0.34);
         const baseY = record ? -size * 0.12 : 0;
         const fan = toRad(fanAngle);
         const turn = toRad(turnAngle);
         const first = size * spread;
         const packed = first * (1 - clamp(packing, 0, 0.95));
         const side = clamp(Math.round(visibleSide), 1, 5);
         const cards: GalleryCard[] = [];
         for (let i = 0; i < count; i++) {
           const offset = i - position;
           const t = Math.abs(offset);
           if (t > side + 1) continue;
           const sign = Math.sign(offset);
           const near = Math.min(t, 1);
           const outer = Math.min(t, side);
           const opacity = 1 - smoothstep(side - 0.3, side + 0.7, t);
           cards.push({
             image: i,
             id: i,
             x: sign * (t < 1 ? t * first : first + (t - 1) * packed),
             // A gentle arc, like cards fanned in a hand.
             y: baseY - outer * outer * size * 0.01 * (fanAngle / 5),
             z: -depth * (near + Math.max(0, t - 1) * 0.35),
             rotateY: -sign * near * turn,
             rotateZ: -sign * outer * fan,
             width: size,
             height: size,
             radius,
             opacity,
             dim: clamp(dim, 0, 1) * Math.min(1, t / side),
             shadow: clamp(shadow, 0, 1) * opacity,
           });
         }
   
         if (record) {
           // Hover over the focused sleeve lifts its record a little.
           const pointer = gallery.pointer();
           const hit = pointer.inside && !gallery.dragging() ? renderer.pick(pointer.x, pointer.y) : null;
           const hovered = hit !== null && (hit.id === active || hit.id === RECORD_ID);
           // The record belongs to one sleeve: when focus moves on, it tucks back in before following.
           if (memory.owner === undefined) memory.owner = active;
           let target = 0;
           if (memory.owner !== active) {
             if ((memory.offset ?? 0) < 0.02) memory.owner = active;
           } else target = playing ? 1 : hovered ? 0.17 : 0;
           const offset = memory.offset ?? 0;
           if (reducedMotion) {
             memory.offset = target;
             memory.offsetV = 0;
           } else {
             const omega = 13;
             memory.offsetV = (memory.offsetV ?? 0) + (-omega * omega * (offset - target) - 2 * omega * (memory.offsetV ?? 0)) * Math.min(dt, 1 / 30);
             memory.offset = offset + memory.offsetV * Math.min(dt, 1 / 30);
             if (Math.abs(memory.offset - target) < 0.001 && Math.abs(memory.offsetV) < 0.01) {
               memory.offset = target;
               memory.offsetV = 0;
             } else moving = true;
           }
           const spinning = playing && !paused && !reducedMotion && memory.offset > 0.9;
           const spinTarget = spinning ? (rpm / 60) * Math.PI * 2 : 0;
           memory.spinV = (memory.spinV ?? 0) + (spinTarget - (memory.spinV ?? 0)) * (1 - Math.exp(-dt * 3));
           if (!spinning && memory.spinV < 0.01) memory.spinV = 0;
           memory.spin = ((memory.spin ?? 0) + memory.spinV * dt) % (Math.PI * 2);
           if (memory.spinV) moving = true;
   
           const sleeve = cards.find((card) => card.id === memory.owner);
           const lift = memory.offset;
           if (sleeve && lift > 0.001) {
             // While playing, the sleeve dips to make room for the record above it.
             sleeve.y -= lift * size * 0.3;
             const rz = sleeve.rotateZ ?? 0;
             const distance = lift * size * 0.98;
             const cx = sleeve.x - Math.sin(rz) * distance;
             const cy = sleeve.y + Math.cos(rz) * distance;
             const disc = size * 0.96;
             const base = { id: RECORD_ID, x: cx, y: cy, rotateY: sleeve.rotateY, opacity: sleeve.opacity, round: 1 };
             cards.push(
               { ...base, image: vinylIndex, z: sleeve.z - 2, rotateZ: rz - memory.spin, width: disc, height: disc, shadow: 0.5 * (sleeve.opacity ?? 1) },
               { ...base, image: memory.owner, z: sleeve.z - 1.6, rotateZ: rz - memory.spin, width: disc * 0.36, height: disc * 0.36 },
               { ...base, image: -1, z: sleeve.z - 1.4, rotateZ: 0, width: disc * 0.035, height: disc * 0.035, fill: [0.92, 0.92, 0.93, 1] },
             );
             if (sheen && renderer.isLoaded(sheenIndex)) cards.push({ ...base, image: sheenIndex, z: sleeve.z - 1.2, rotateZ: rz, width: disc, height: disc });
           }
         }
   
         return {
           cards,
           animating: moving,
           scene: { fov: 32, shadowOffset: 12, shadowBlur: 20, shadowOpacity: 0.26, edgeFade: [0.06, 0] },
         };
       },
     });
   
     const { next, previous, goTo, hold, scrub, scrubEnd, activeIndex } = input;
     useEffect(() => {
       hold("playing", playing);
     }, [hold, playing]);
   
     useImperativeHandle(
       ref,
       () => ({
         next,
         previous,
         goTo: (index: number) => goTo(index),
         play: () => setPlay(true, activeIndex()),
         stop: () => setPlay(false, activeIndex()),
       }),
       [next, previous, goTo, activeIndex, setPlay],
     );
   
     // "auto" accent: the most vivid color of the focused artwork (cached per image).
     const focused = items[input.index];
     const autoSrc = focused?.src ?? "";
     const dark = scheme === "dark";
     useEffect(() => {
       if (accentColor !== "auto" || !autoSrc) return;
       const key = `${autoSrc}|${dark}`;
       let cancelled = false;
       const cached = accentCache.get(key);
       const image = new Image();
       image.crossOrigin = "anonymous";
       image.src = autoSrc;
       (cached ? Promise.resolve() : image.decode()).then(
         () => {
           const color = cached ?? vividAccent(image, dark) ?? DEFAULT_ACCENT;
           accentCache.set(key, color);
           if (!cancelled) setAutoAccent({ src: key, color });
         },
         () => {},
       );
       return () => {
         cancelled = true;
       };
     }, [accentColor, autoSrc, dark]);
     const accent = accentColor === "auto" ? (autoAccent?.src === `${autoSrc}|${dark}` ? autoAccent.color : (autoAccent?.color ?? DEFAULT_ACCENT)) : accentColor;
   
     const onRulerDown = (event: PointerEvent<HTMLDivElement>) => {
       event.currentTarget.setPointerCapture(event.pointerId);
       scrubbing.current = { id: event.pointerId, x: event.clientX, moved: false };
     };
     const onRulerMove = (event: PointerEvent<HTMLDivElement>) => {
       const drag = scrubbing.current;
       if (!drag || drag.id !== event.pointerId) return;
       const dx = event.clientX - drag.x;
       if (!drag.moved && Math.abs(dx) < 4) return;
       drag.moved = true;
       drag.x = event.clientX;
       scrub(-dx / TICK);
     };
     const onRulerUp = (event: PointerEvent<HTMLDivElement>) => {
       const drag = scrubbing.current;
       scrubbing.current = null;
       if (!drag || drag.id !== event.pointerId) return;
       if (drag.moved) return scrubEnd();
       // A click jumps to the tick under the pointer.
       const rect = event.currentTarget.getBoundingClientRect();
       goTo(activeIndex() + Math.round((event.clientX - rect.left - rect.width / 2) / TICK));
     };
   
     const fallback = status === "fallback";
     const muted = scheme === "dark" ? "bg-white/30" : "bg-foreground/25";
     const button = cn(
       "grid size-9 shrink-0 cursor-pointer place-items-center rounded-full outline-none transition-[background-color,transform] duration-150 active:scale-[0.94] focus-visible:ring-2 focus-visible:ring-ring motion-reduce:transition-none",
       scheme === "dark" ? "text-white hover:bg-white/10" : "text-foreground hover:bg-surface-2",
     );
   
     return (
       <div
         ref={bind}
         role="group"
         aria-roledescription="carousel"
         aria-label={ariaLabel}
         // Focusable by click (not by Tab) so Escape and arrow keys work after pointer use.
         tabIndex={-1}
         className={cn("relative outline-none flex size-full min-h-[420px] touch-pan-y flex-col rounded-[inherit] select-none has-[:focus-visible]:ring-2 has-[:focus-visible]:ring-ring", className)}
         style={{ backgroundColor, "--sleeve-accent": accent, ...style } as CSSProperties}
       >
         <div ref={hostRef} className="relative min-h-0 flex-1">
           {fallback ? <GalleryFallback items={items} label={ariaLabel} aspect="1 / 1" onSelect={onSelect} className="absolute inset-0" /> : null}
         </div>
         {fallback ? null : (
           <GalleryA11y
             items={items}
             index={input.index}
             label={ariaLabel}
             live={!autoplay || paused}
             onFocusItem={(i) => goTo(i)}
             onActivate={(i) => {
               if (i !== input.index) return goTo(i);
               if (!playing) onSelect?.(items[i], i);
               setPlay(!playing, i);
             }}
           />
         )}
         {captions && !fallback ? <GalleryCaption item={focused} index={input.index} count={count} scheme={scheme} className="mx-auto h-11 w-full max-w-xs shrink-0 text-center" /> : null}
         {controls && !fallback ? (
           <div data-gallery-control className="relative mx-auto flex h-[52px] w-full max-w-md shrink-0 items-center gap-1 px-3">
             <button type="button" data-gallery-control aria-label="Previous album" onClick={previous} disabled={input.index <= 0} className={cn(button, "disabled:pointer-events-none disabled:opacity-35")}>
               <ChevronLeft className="size-4" aria-hidden="true" />
             </button>
             <div
               aria-hidden="true"
               onPointerDown={onRulerDown}
               onPointerMove={onRulerMove}
               onPointerUp={onRulerUp}
               onPointerCancel={onRulerUp}
               className="relative h-full flex-1 cursor-ew-resize touch-none overflow-hidden [mask-image:linear-gradient(90deg,transparent,black_20%,black_80%,transparent)]"
             >
               <div ref={ticks} className="absolute inset-y-0 left-1/2">
                 {items.map((item, i) => (
                   <span
                     key={`${item.src}-${i}`}
                     className={cn(
                       // Ticks are 20px tall and scale down from the base (transform only).
                       "absolute bottom-3 h-5 w-px origin-bottom -translate-x-1/2 rounded-full transition-[scale,background-color] duration-200 motion-reduce:transition-none",
                       i === input.index ? (record ? "scale-y-0" : "scale-y-100 bg-[var(--sleeve-accent)]") : i % 5 === 0 ? cn("scale-y-80", muted) : cn("scale-y-50", muted),
                     )}
                     style={{ left: i * TICK }}
                   />
                 ))}
               </div>
             </div>
             {record ? (
               <button
                 type="button"
                 data-gallery-control
                 aria-label={`${playing ? "Stop" : "Play"} ${focused?.title ?? "album"}`}
                 aria-pressed={playing}
                 onClick={() => {
                   if (!playing) onSelect?.(items[input.index], input.index);
                   setPlay(!playing, input.index);
                 }}
                 className="absolute left-1/2 grid size-10 -translate-x-1/2 cursor-pointer place-items-center rounded-full bg-[var(--sleeve-accent)] text-white shadow-md transition-[transform,background-color] duration-200 outline-none active:scale-[0.94] focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 motion-reduce:transition-none"
               >
                 {playing ? <Pause className="size-4 fill-current" aria-hidden="true" /> : <Play className="ml-0.5 size-4 fill-current" aria-hidden="true" />}
               </button>
             ) : null}
             <button type="button" data-gallery-control aria-label="Next album" onClick={next} disabled={input.index >= count - 1} className={cn(button, "disabled:pointer-events-none disabled:opacity-35")}>
               <ChevronRight className="size-4" aria-hidden="true" />
             </button>
           </div>
         ) : null}
       </div>
     );
   }

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