| 1 | import { type CSSProperties, type ReactNode, useEffect, useRef, useState } from "react"; |
| 2 | import { useLocation } from "react-router"; |
| 3 | |
| 4 | import { cn } from "../../lib/cn"; |
| 5 | |
| 6 | /** How far the fade reaches in from an edge with more tabs past it. */ |
| 7 | const FADE = "1.5rem"; |
| 8 | |
| 9 | /** The fade at either end that has more tabs beyond it. */ |
| 10 | function fade(start: boolean, end: boolean): CSSProperties | undefined { |
| 11 | if (!start && !end) return undefined; |
| 12 | const mask = `linear-gradient(to right, ${start ? "transparent" : "#000"}, #000 ${start ? FADE : "0px"}, #000 calc(100% - ${end ? FADE : "0px"}), ${end ? "transparent" : "#000"})`; |
| 13 | return { maskImage: mask, WebkitMaskImage: mask }; |
| 14 | } |
| 15 | |
| 16 | /** The current tab (`aria-current="page"` or `data-active`) scrolled into view, without scrolling the page. */ |
| 17 | function reveal(strip: HTMLElement) { |
| 18 | // A tab that says it is current wins over a link that only contains the address. |
| 19 | const current = strip.querySelector<HTMLElement>('[data-active="true"]') ?? strip.querySelector<HTMLElement>('[aria-current="page"]'); |
| 20 | if (!current) return; |
| 21 | const left = current.offsetLeft; |
| 22 | const right = left + current.offsetWidth; |
| 23 | if (left < strip.scrollLeft) strip.scrollLeft = Math.max(0, left - 24); |
| 24 | else if (right > strip.scrollLeft + strip.clientWidth) strip.scrollLeft = right - strip.clientWidth + 24; |
| 25 | } |
| 26 | |
| 27 | /** |
| 28 | * A row of tabs that never wraps: on a narrow screen it scrolls sideways, |
| 29 | * with no scrollbar, faded at an edge that has more beyond it, and the |
| 30 | * current tab (`aria-current="page"` or `data-active`) kept in view. |
| 31 | */ |
| 32 | export function TabStrip({ label, className, children }: { label?: string; className?: string; children: ReactNode }) { |
| 33 | const ref = useRef<HTMLElement>(null); |
| 34 | const [edges, setEdges] = useState({ start: false, end: false }); |
| 35 | const { pathname, search } = useLocation(); |
| 36 | |
| 37 | useEffect(() => { |
| 38 | const strip = ref.current; |
| 39 | if (!strip) return; |
| 40 | const measure = () => { |
| 41 | const start = strip.scrollLeft > 1; |
| 42 | const end = strip.scrollLeft + strip.clientWidth < strip.scrollWidth - 1; |
| 43 | setEdges((now) => (now.start === start && now.end === end ? now : { start, end })); |
| 44 | }; |
| 45 | measure(); |
| 46 | strip.addEventListener("scroll", measure, { passive: true }); |
| 47 | // A new width (the first layout, a rotated phone) can hide the current tab. |
| 48 | const observer = |
| 49 | typeof ResizeObserver === "undefined" |
| 50 | ? null |
| 51 | : new ResizeObserver(() => { |
| 52 | reveal(strip); |
| 53 | measure(); |
| 54 | }); |
| 55 | observer?.observe(strip); |
| 56 | return () => { |
| 57 | strip.removeEventListener("scroll", measure); |
| 58 | observer?.disconnect(); |
| 59 | }; |
| 60 | }, []); |
| 61 | |
| 62 | useEffect(() => { |
| 63 | if (ref.current) reveal(ref.current); |
| 64 | }, [pathname, search]); |
| 65 | |
| 66 | return ( |
| 67 | <nav |
| 68 | ref={ref} |
| 69 | aria-label={label} |
| 70 | style={fade(edges.start, edges.end)} |
| 71 | className={cn( |
| 72 | "relative flex overflow-x-auto overflow-y-hidden whitespace-nowrap [scrollbar-width:none] [&::-webkit-scrollbar]:hidden [&>*]:shrink-0", |
| 73 | className, |
| 74 | )} |
| 75 | > |
| 76 | {children} |
| 77 | </nav> |
| 78 | ); |
| 79 | } |