Glow icon

// Copyright (c) 2026 Bruno Delorence. MIT License.'use client';import {  useEffect,  useLayoutEffect,  useRef,  useState,  type CSSProperties,  type KeyboardEvent,  type PointerEvent,} from 'react';import { IconArt, type Mood } from './icon-art';import { Phone } from './phone';import { SETTINGS, type SettingId } from './settings';import { easingOf, spring } from './spring';import { runTimeline } from './timeline';import { useAutoplay } from './use-autoplay';import styles from './glow-icon.module.css';/* * Glow icon: a living app icon. A little ghost floats in a glassy rounded square, glowing from * within; it looks at the pointer, blinks now and then, and jumps when the icon is pressed. A

/* Glow icon (glow-icon.tsx): a light stage with the scene, the setting the icon is shown in, and   the switch under it; at night the stage and the switch go dark, and the scene (the icon, its   glow, the phone and the three backdrops) keeps its colours. The backdrop's colours are   registered custom properties, so a change of setting cross-fades it; the pointer's place   (--gi-px, --gi-py) and --gi-look are registered so that the demo can glide them and the eyes   ease back. Prefixed, as @property names are global. */@property --gi-top {  syntax: '<color>';  inherits: true;  initial-value: #7d43f0;}@property --gi-middle {  syntax: '<color>';  inherits: true;  initial-value: #6a2fdc;}@property --gi-bottom {  syntax: '<color>';  inherits: true;  initial-value: #5b24c8;}@property --gi-px {  syntax: '<length>';

'use client';import { useId, type Ref } from 'react';import styles from './glow-icon.module.css';/* * The app icon: a rounded square with a deep violet rim around a lavender face, and a little ghost * floating in it, glowing from within. All of it is SVG and CSS, and every glow is a radial * gradient: no blur filters. * * - The ghost is milky and translucent: its body is one radial gradient, violet light at its *   heart fading to white at the edge, with a rim of light on the side the light comes from and a *   glint on its head. Its two glassy eyes are a gradient of dark violet with two glints. * - Around it, a soft halo on the face and a pool of light on the floor, which breathes as it *   floats. * - The icon is built as a few layers: the face, the ghost (which floats, and leans and looks), *   and the glass on top: a fixed sheen, and a specular spot that slides as the icon tilts. *//** How the ghost feels: calm, or startled while the icon is held down. */export type Mood = 'calm' | 'startled';export function IconArt({  label,

'use client';import { useId } from 'react';import styles from './glow-icon.module.css';/* * The phone of the "Phone" setting: the top corner of a phone held at an angle, with a steel edge * and its side buttons, a dark screen, and a grid of plain, dimmed placeholder icons. The first * slot is left empty: the icon flies there. Drawn in phone units (1000 wide); the stylesheet * places and turns it, and the icon's slot is worked out from the same numbers. *//** An icon's size on the screen, the step from one to the next, and the first one's corner. */const ICON = 172;const STEP = { x: 248, y: 268 };const FIRST = { x: 106, y: 160 };/** The placeholders around the icon's slot: column, row, and a dim tint. */const APPS = [  { column: 1, row: 0, tint: 'rgb(84 190 110 / 0.3)' },  { column: 2, row: 0, tint: 'rgb(255 255 255 / 0.1)' },  { column: 3, row: 0, tint: 'rgb(255 168 76 / 0.22)' },  { column: 0, row: 1, tint: 'rgb(70 140 255 / 0.28)' },  { column: 1, row: 1, tint: 'rgb(255 255 255 / 0.12)' },

/* * The settings the icon is shown in: a vivid purple backdrop, the home screen of a phone held at * an angle, and a light backdrop. Each sets the backdrop's three colours, which the stylesheet * transitions as registered custom properties, so a change of setting cross-fades the backdrop. */export type SettingId = 'purple' | 'phone' | 'light';export type Setting = {  id: SettingId;  /** Its button's label. */  label: string;  /** Where it puts the icon, as read out: "On a purple backdrop." */  place: string;  /** The backdrop, from top to bottom. */  top: string;  middle: string;  bottom: string;};export const SETTINGS: readonly Setting[] = [  {    id: 'purple',    label: 'Purple',

/* * The demo's timeline: a script of awaited waits. Stopping it (the reader takes over, or the icon * scrolls away) rejects the wait in progress, which ends the script right there; nothing of it * runs afterwards. *//** What a stopped timeline's pending wait rejects with. */class Stopped extends Error {}/** Plays `script`; returns the function that stops it. */export function runTimeline(script: (wait: (ms: number) => Promise<void>) => Promise<void>) {  let alive = true;  const timers = new Set<number>();  const pending = new Set<() => void>();  const wait = (ms: number) =>    new Promise<void>((resolve, reject) => {      if (!alive) return reject(new Stopped());      const cancel = () => reject(new Stopped());      const timer = window.setTimeout(() => {        timers.delete(timer);        pending.delete(cancel);        resolve();      }, ms);

/* * Springs as CSS easings. A spring pulls a value to its target and lets it settle: fast at first, * then slowing down, overshooting a little and coming back if it is bouncy. CSS `linear()` draws * any curve through a list of points, so the spring's motion is sampled once, and the same curve * serves CSS transitions and the Web Animations API. */export type Spring = {  /** The curve, as a CSS `linear()` easing. */  easing: string;  /** How long it takes to settle, in ms: the duration to play the curve over. */  duration: number;};/** Points sampled along the curve: plenty for a smooth motion. */const SAMPLES = 40;/** * A spring that covers most of the distance in about `response` ms. With a `bounce` of 0 it * settles without overshooting; at 0.3 it overshoots by about 5% and comes back. */export function spring(bounce: number, response: number): Spring {  // The damping ratio (1: no overshoot) and the natural frequency, in radians per second.  const damping = 1 - bounce;

'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;