Lens Text

1"use client"
2 
3import * as React from "react"
4 
5import { cn } from "@/lib/utils"
6 
7export interface LensTextProps extends React.ComponentProps<"span"> {
8  /** Blur radius of the resting text, in pixels. */
9  blur?: number
10  /** Diameter of the lens in pixels. */
11  size?: number
12  /** How much of the lens fades out at its edge, from `0` to `1`. */
13  feather?: number
14  /** Scale applied to the text under the lens. `1` is a plain focus window. */
15  magnify?: number
16  /** Corner radius of the frosted panel. Any CSS length; `em` scales with the type. */
17  radius?: string
18  /**
19   * Milliseconds the lens takes to catch up to the pointer, and the pace it
20   * opens and closes at. `0` locks it to the pointer.
21   */
22  follow?: number
23  /** Draw a hairline ring around the lens. */
24  ring?: boolean
25  /** Render the text sharp, with no blur and no lens. */
26  disabled?: boolean
27}
28 
29/**
30 * A hovering pointer is the only way to aim the lens, so anything else (touch,
31 * pen, keyboard-only) gets the text sharp rather than never getting it at all.
32 */
33const HOVER_QUERY = "(hover: hover) and (pointer: fine)"
34const MOTION_QUERY = "(prefers-reduced-motion: reduce)"
35 
36/** The lens opens slower than it tracks, or it pops on the way in. */
37const OPEN_FACTOR = 1.6
38 
39/**
40 * Room for the blur to fall off inside the panel rather than at its edge.
41 * In `em` so it tracks the type it is wrapped around.
42 */
43const PANEL_PADDING = "0.28em 0.45em"
44 
45function useMediaQuery(query: string, fallback: boolean) {
46  // Server and first client paint agree on `fallback`. The effect corrects it
47  // before anyone can interact, so there is no hydration mismatch.
48  const [matches, setMatches] = React.useState(fallback)
49 
50  React.useEffect(() => {
51    const list = window.matchMedia(query)
52    const sync = () => setMatches(list.matches)
53 
54    sync()
55    list.addEventListener("change", sync)
56    return () => list.removeEventListener("change", sync)
57  }, [query])
58 
59  return matches
60}
61 
62function clamp01(value: number) {
63  return Math.min(Math.max(value, 0), 1)
64}
65 
66export function LensText({
67  children,
68  className,
69  blur = 8,
70  size = 110,
71  feather = 0.5,
72  magnify = 1,
73  radius = "0.35em",
74  follow = 130,
75  ring = false,
76  disabled = false,
77  style,
78  ...props
79}: LensTextProps) {
80  const ref = React.useRef<HTMLSpanElement>(null)
81  const frame = React.useRef(0)
82  const running = React.useRef(false)
83  const hasHover = useMediaQuery(HOVER_QUERY, true)
84  const reduceMotion = useMediaQuery(MOTION_QUERY, false)
85 
86// … truncated