Media scrub

// Copyright (c) 2026 Bruno Delorence. MIT License.'use client';import {  memo,  useCallback,  useEffect,  useEffectEvent,  useId,  useMemo,  useRef,  useState,  type CSSProperties,  type PointerEvent,} from 'react';import { Avatar } from './avatars';import { FILES, TEAM, type MediaFile, type Presence, type Teammate } from './files';import { GhostPointer, runDemo, type Demo } from './ghost-pointer';import { ChevronIcon, FilmIcon, MoreIcon, PlayIcon, PlusIcon, SearchIcon, WaveIcon } from './icons';import { Scene } from './scenes';import { useAutoplay } from './use-autoplay';import { Waveform } from './waveform';import styles from './media-scrub.module.css';

/* Media scrub (media-scrub.tsx): a stage with the library's panel in its middle. A card's   data-active is set while it is scrubbed or played; --head, --peer and --color, set on each   thumbnail, place and paint the playheads, as shares of the thumbnail's width (so no token below   may take those names).   The interface's colours are the tokens below, each light-dark(light, dark): the component takes   the color-scheme it inherits from the page (light unless the page says otherwise), or the one   its colorScheme prop sets (data-color-scheme). The clips' pictures (scenes.tsx) and the   teammates' faces and colours are content: the same in both schemes. */.root {  /* The stage, and the panel raised on it: a step lighter at night. */  --surface: #e8e8eb;  --surface-2: #fff;  /* The stage's dots; the fields (search, filter), the … button's hover; a picture not drawn yet. */  --dots: rgb(0 0 0 / 0.05);  --wash: #f2f2f5;  --placeholder: #d9d9de;  /* The words and the icons. */  --ink: #1d1d1f;  --ink-muted: #86868b;  /* Hairlines: the stage's edge, the panel's, round each picture, and the empty state's dashes. */  --line: rgb(0 0 0 / 0.06);  --panel-edge: rgb(0 0 0 / 0.04);

/* * The clips, drawn in code: three landscapes, each a pure function of time, so any frame of a * "video" can be shown without a video file. A frame is an SVG of a dozen shapes: a sky gradient, * a sun or a moon on its arc, drifting clouds, ridges that pan at different speeds (nearer ones * faster, so the camera seems to move) and a few details with a life of their own. * * The ridges' outlines are made once, from a seeded random generator, so the server and the * browser draw the same first frame. From one frame to the next only transforms, colours and a * few short paths change. */import type { ReactNode } from 'react';export type SceneName = 'canyon' | 'harbor' | 'alpine';/** The frame, in SVG units: 16:9. */const W = 160;const H = 90;type Point = [number, number];type Rgb = readonly [number, number, number];/** Colours along the clip: [share of the clip, colour]. */type Keys = readonly (readonly [number, Rgb])[];/** What a scene draws a frame from: its ids' prefix, the time in seconds, the share of the clip. */

/* * An audio file's thumbnail: its waveform as a row of rounded bars. The bars are one path, drawn * twice: dim, then bright through a clip that ends at the playhead, so moving the playhead only * changes the width of one rectangle. */import styles from './media-scrub.module.css';/** Each bar's slot, in SVG units; the bars are a little thinner, with round ends. */const SLOT = 3;const HEIGHT = 40;export function Waveform({  levels,  share,  id,  className,}: {  /** How loud the sound is along its length, one bar each, from 0 to 1. */  levels: readonly number[];  /** How much of it is lit, from 0 to 1. */  share: number;  /** Keeps its clip apart from other waveforms' on the page. */  id: string;

import type { Face } from './avatars';import type { SceneName } from './scenes';/* * The library's sample content: four made-up files and the three people it is shared with. A * video names one of the drawn scenes (scenes.tsx); an audio file carries its waveform. *//** A clip whose frames are drawn in code. */export type VideoFile = {  kind: 'video';  id: string;  name: string;  /** Its length, in seconds. */  duration: number;  /** A badge on the thumbnail, such as "4K". */  badge?: string;  /** The drawn scene that plays in the thumbnail. */  scene: SceneName;  /** The frame the thumbnail shows at rest, in seconds. */  poster: number;};/** A sound, shown as its waveform. */

/* * Small illustrated teammates: no photos, so the demo needs no image files and shows no real * faces. Use an <img> in their place for real people. */export type Face = {  /** The backdrop, behind the head. */  bg: string;  skin: string;  hair: string;  shirt: string;  hairStyle: 'short' | 'long' | 'bun' | 'curly';  glasses?: boolean;};/** A face in a circle, drawn in a 24 × 24 box. Decorative: name the person around it. */export function Avatar({ face, className }: { face: Face; className?: string }) {  const { bg, skin, hair, shirt, hairStyle, glasses } = face;  return (    <svg className={className} viewBox="0 0 24 24" aria-hidden="true">      <circle cx="12" cy="12" r="12" fill={bg} />      {hairStyle === 'long' && (        <path          d="M6.6 11.8c-.6-4.7 1.9-7.6 5.4-7.6s6 2.9 5.4 7.6c.3 2.5.8 4.2 1.7 5.5-2.7.8-5 .4-7.1-.6-2.1 1-4.4 1.4-7.1.6.9-1.3 1.4-3 1.7-5.5Z"

/* The panel's icons, drawn on a 16 × 16 grid in the current colour. All decorative. */type IconProps = { className?: string };export function PlusIcon({ className }: IconProps) {  return (    <svg className={className} viewBox="0 0 16 16" aria-hidden="true">      <path        d="M8 3.2v9.6M3.2 8h9.6"        fill="none"        stroke="currentColor"        strokeWidth="1.7"        strokeLinecap="round"      />    </svg>  );}export function SearchIcon({ className }: IconProps) {  return (    <svg className={className} viewBox="0 0 16 16" aria-hidden="true">      <circle cx="7.1" cy="7.1" r="4.4" fill="none" stroke="currentColor" strokeWidth="1.5" />      <path d="m10.4 10.4 3.1 3.1" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" />    </svg>

'use client';import type { CSSProperties, Ref } from 'react';/* * The demo's ghost pointer, and the timeline that moves it. A demo is a script of awaited steps: * wait, glide the pointer onto a card, sweep it across a thumbnail while the card scrubs, press. * Steps can run side by side (the teammate scrubs while the pointer does). Stopping the demo (the * reader takes over, or it scrolls away) ends every step in progress at once: their promises * reject, which ends the scripts right there, and the pointer fades out. */type Point = { x: number; y: number };export type Demo = {  /** Resolves after `ms`. */  wait: (ms: number) => Promise<void>;  /** Glides the pointer onto `target`: its middle, or a point given as shares of its size. */  moveTo: (target: Element | null | undefined, at?: Point) => Promise<void>;  /**   * Sweeps the pointer across `target`, from one share of its width to another, at the height it   * is at; `onShare` gets the share under the pointer on every frame.   */  sweep: (

'use client';import { useCallback, useEffect, useRef, useState } from 'react';/* * When a demo may play on its own: while part of it is on screen and the tab is visible, never * under reduced motion, and not while the reader is using it. `take()` hands it to the reader; it * takes back over `idle` ms after their last input. */export function useAutoplay<T extends HTMLElement>(idle = 6000) {  const ref = useRef<T>(null);  const [visible, setVisible] = useState(false);  const [reduced, setReduced] = useState(true);  const [taken, setTaken] = useState(false);  const timer = useRef(0);  useEffect(() => {    const element = ref.current;    if (!element) return;    let onScreen = false;    const update = () => setVisible(onScreen && !document.hidden);    const observer = new IntersectionObserver(      ([entry]) => {        onScreen = entry.isIntersecting;