Encrypted Card

1"use client";
2 
3import * as React from "react";
4 
5export type EncryptedCardProps = React.HTMLAttributes<HTMLDivElement> & {
6  /** Pool of glyphs the encrypted stream is drawn from. */
7  characters?: string;
8  /** Milliseconds between glyph re-randomizations while hovered. */
9  speed?: number;
10  /** Radius of the reveal window that follows the pointer, in pixels. */
11  revealRadius?: number;
12  /** Color of the encrypted glyph stream. Accepts any CSS color. */
13  streamColor?: string;
14  /**
15   * Opacity of the revealed glyph stream, 0–1. Lower values make the ciphertext
16   * subtler. Defaults to 1 (fully opaque inside the reveal window).
17   */
18  streamOpacity?: number;
19};
20 
21// A wide alphabet keeps the stream looking like ciphertext rather than a word.
22const DEFAULT_CHARS =
23  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789<>[]{}/*#$%&";
24// Enough characters to flood any reasonably sized card.
25const STREAM_LEN = 1500;
26 
27const ROOT_BASE =
28  "group relative overflow-hidden rounded-xl border border-border bg-card text-card-foreground";
29 
30// The glyph layer, revealed only inside a soft radial mask centered on the
31// pointer (`--x` / `--y`, defaulting to center so the first paint isn't a corner
32// flash). `mask-image` is a single longhand so the shorthand-reset trap does not
33// apply here.
34const STREAM_BASE =
35  "pointer-events-none absolute inset-0 select-none break-all font-mono text-[11px] leading-[1.15] tracking-[0.15em] opacity-0 [transition:opacity_300ms_ease] group-hover:[opacity:var(--stream-opacity,1)] motion-reduce:[transition:none] [mask-image:radial-gradient(var(--reveal)_circle_at_var(--x,50%)_var(--y,50%),#000_0%,transparent_100%)] [-webkit-mask-image:radial-gradient(var(--reveal)_circle_at_var(--x,50%)_var(--y,50%),#000_0%,transparent_100%)]";
36 
37function randomString(length: number, chars: string): string {
38  let out = "";
39  for (let i = 0; i < length; i++) {
40    out += chars[Math.floor(Math.random() * chars.length)];
41  }
42  return out;
43}
44 
45function usePrefersReducedMotion(): boolean {
46  const [reduced, setReduced] = React.useState(false);
47  React.useEffect(() => {
48    const mq = window.matchMedia("(prefers-reduced-motion: reduce)");
49    const update = () => setReduced(mq.matches);
50    update();
51    mq.addEventListener("change", update);
52    return () => mq.removeEventListener("change", update);
53  }, []);
54  return reduced;
55}
56 
57const EncryptedCard = React.forwardRef<HTMLDivElement, EncryptedCardProps>(
58  (
59    {
60// … truncated