Testimonial Wall

1"use client"
2 
3import * as React from "react"
4 
5import { cn } from "@/lib/utils"
6import { useInViewport } from "@/registry/lib/use-in-viewport"
7 
8export interface TestimonialWallProps extends React.ComponentProps<"div"> {
9  /** Columns at the widest breakpoint. Narrow screens drop the extras. */
10  columns?: number
11  /** Seconds for one pass of the first column. */
12  duration?: number
13  /** Per-column multipliers on `duration`. Falls back to a fixed drift. */
14  speeds?: number[]
15  /** Gap between cards and between columns, as a CSS length. */
16  gap?: string
17  /** Stop every column while the pointer is over the wall. */
18  pauseOnHover?: boolean
19  /** Render the wall static. */
20  paused?: boolean
21  /** Fade the top and bottom out. Pass a CSS length to size the fade. */
22  fade?: boolean | string
23}
24 
25/**
26 * Alpha sampled off a smoothstep curve. A two-stop gradient ramps linearly, and
27 * the eye reads where that ramp meets full opacity as a hard line. Sampling the
28 * curve rounds both ends off, so the fade runs out instead of stopping.
29 */
30const FADE_STOPS = [0, 0.0608, 0.216, 0.5, 0.784, 0.939, 1]
31 
32function fadeMask(size: string) {
33  const last = FADE_STOPS.length - 1
34  const ratio = (index: number) => (index / last).toFixed(4)
35 
36  const leading = FADE_STOPS.map(
37    (alpha, index) => `rgb(0 0 0 / ${alpha}) calc(${size} * ${ratio(index)})`
38  )
39  const trailing = FADE_STOPS.map(
40    (_, index) =>
41      `rgb(0 0 0 / ${FADE_STOPS[last - index]}) calc(100% - ${size} * ${ratio(
42        last - index
43      )})`
44  )
45 
46  return `linear-gradient(to bottom, ${[...leading, ...trailing].join(", ")})`
47}
48 
49/** Columns past the first are dropped rather than squeezed on small screens. */
50const VISIBILITY = ["flex", "hidden sm:flex", "hidden lg:flex"]
51 
52export function TestimonialWall({
53  children,
54  className,
55  columns = 3,
56  duration = 44,
57  speeds,
58  gap = "1rem",
59  pauseOnHover = true,
60  paused = false,
61  fade = true,
62  style,
63  ...props
64}: TestimonialWallProps) {
65  const items = React.Children.toArray(children)
66  // Dealt round robin, so a wall of uneven cards still balances out.
67  const lanes = Array.from({ length: Math.max(columns, 1) }, (_, lane) =>
68    items.filter((_, index) => index % Math.max(columns, 1) === lane)
69  )
70 
71  const mask = fade ? fadeMask(fade === true ? "14%" : fade) : undefined
72 
73  const root = React.useRef<HTMLDivElement>(null)
74  const onScreen = useInViewport(root)
75 
76  return (
77    <div
78      ref={root}
79      data-slot="testimonial-wall"
80// … truncated