Theme Toggler

1"use client"
2 
3import { useCallback, useEffect, useRef, useState } from "react"
4import { Moon, Sun } from "lucide-react"
5import { flushSync } from "react-dom"
6 
7import { cn } from "@/lib/utils"
8 
9export type TransitionVariant =
10  | "circle"
11  | "square"
12  | "triangle"
13  | "diamond"
14  | "hexagon"
15  | "rectangle"
16  | "star"
17 
18interface AnimatedThemeTogglerProps extends React.ComponentPropsWithoutRef<"button"> {
19  duration?: number
20  variant?: TransitionVariant
21  /** When true, the transition expands from the viewport center instead of the button center. */
22  fromCenter?: boolean
23  /**
24   * Controlled theme value. When provided, the parent owns persistence
25   * (e.g. `next-themes`) and this component will not write to localStorage.
26   */
27  theme?: "light" | "dark"
28  /** Called on toggle. Pair with `theme` for controlled usage. */
29  onThemeChange?: (theme: "light" | "dark") => void
30}
31 
32function polygonCollapsed(point: string, vertexCount: number): string {
33  const pairs = Array.from({ length: vertexCount }, () => point).join(", ")
34  return `polygon(${pairs})`
35}
36 
37// All coordinates are percentages of the snapshot reference box: Chrome 150
38// renders absolute px clip-path coordinates on ::view-transition-new(root)
39// unscaled on fractional display scales (e.g. Windows 150%) for the first
40// transition after load, so px values land at the wrong position (#989).
41function getThemeTransitionClipPaths(
42  variant: TransitionVariant,
43  cx: number,
44  cy: number,
45  maxRadius: number,
46  viewportWidth: number,
47  viewportHeight: number
48): [string, string] {
49  const toX = (x: number) => `${(x / viewportWidth) * 100}%`
50  const toY = (y: number) => `${(y / viewportHeight) * 100}%`
51  const point = (x: number, y: number) => `${toX(x)} ${toY(y)}`
52  // circle() percentage radii resolve against hypot(w, h) / sqrt(2) of the reference box.
53  const toRadius = (r: number) =>
54    `${(r / (Math.hypot(viewportWidth, viewportHeight) / Math.SQRT2)) * 100}%`
55 
56  switch (variant) {
57    case "circle":
58      return [
59        `circle(0% at ${point(cx, cy)})`,
60        `circle(${toRadius(maxRadius)} at ${point(cx, cy)})`,
61      ]
62    case "square": {
63      const halfW = Math.max(cx, viewportWidth - cx)
64      const halfH = Math.max(cy, viewportHeight - cy)
65      const halfSide = Math.max(halfW, halfH) * 1.05
66      const end = [
67        point(cx - halfSide, cy - halfSide),
68        point(cx + halfSide, cy - halfSide),
69        point(cx + halfSide, cy + halfSide),
70// … truncated