| 1 | // Publishes the shell bar's measured height as --app-bar-height on the document |
| 2 | // root. The bar is the layout's first grid row and sizes to its own content, so |
| 3 | // the two consumers that position themselves against its bottom edge — the |
| 4 | // sidebar resizer and the overlay dock — cannot read the height from CSS. It is |
| 5 | // not a constant: it differs per layout style, theme skin and platform caption. |
| 6 | import { useEffect } from "react"; |
| 7 | |
| 8 | const VAR = "--app-bar-height"; |
| 9 | |
| 10 | export function useTopicbarHeightVar(): void { |
| 11 | useEffect(() => { |
| 12 | const publish = () => { |
| 13 | const bar = document.querySelector<HTMLElement>(".topicbar"); |
| 14 | if (!bar) return; |
| 15 | const height = Math.round(bar.getBoundingClientRect().height); |
| 16 | if (height > 0) document.documentElement.style.setProperty(VAR, `${height}px`); |
| 17 | }; |
| 18 | publish(); |
| 19 | const bar = document.querySelector<HTMLElement>(".topicbar"); |
| 20 | if (!bar || typeof ResizeObserver === "undefined") { |
| 21 | window.addEventListener("resize", publish); |
| 22 | return () => window.removeEventListener("resize", publish); |
| 23 | } |
| 24 | const observer = new ResizeObserver(publish); |
| 25 | observer.observe(bar); |
| 26 | return () => { |
| 27 | observer.disconnect(); |
| 28 | document.documentElement.style.removeProperty(VAR); |
| 29 | }; |
| 30 | }, []); |
| 31 | } |
| 32 |