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Maurice
e4ed4bfc7b
On the phone a flick of the sheet's top edge, a tap on the scrim or Escape closed the booking, transport and place forms and threw away whatever had been typed, without a word; the desktop dialogs have asked since #2253. The question moves into a shared hook that DialogShell and MSheet both use, and the three sheets pass their form state to it.
37 lines
1.6 KiB
TypeScript
37 lines
1.6 KiB
TypeScript
import { useCallback, useEffect, useRef, useState } from 'react'
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const snapshot = (value: unknown): string | null => {
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try { return JSON.stringify(value) ?? null } catch { return null }
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}
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/**
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* The unsaved-changes question (#2253) for a dialog or a sheet. `guard` is the
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* editor's state, JSON-serialisable; undefined turns the question off. The
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* state at the first key or pointer press (`markStart`) is the starting point,
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* so whatever the editor loaded on open does not count as a change. The ways
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* out a hand takes by accident go through `requestClose`, which asks before
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* throwing away a state that differs from that starting point.
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*/
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export function useDiscardGuard(guard: unknown, onClose: () => void) {
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const baseline = useRef<string | null>(null)
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const guardRef = useRef(guard)
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useEffect(() => { guardRef.current = guard })
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const [asking, setAsking] = useState(false)
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const markStart = useCallback(() => {
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if (guardRef.current !== undefined && baseline.current === null) baseline.current = snapshot(guardRef.current)
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}, [])
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const requestClose = useCallback(() => {
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if (guardRef.current !== undefined && baseline.current !== null && snapshot(guardRef.current) !== baseline.current) setAsking(true)
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else onClose()
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}, [onClose])
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const keepEditing = useCallback(() => setAsking(false), [])
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const discard = useCallback(() => { setAsking(false); onClose() }, [onClose])
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/** Forget the starting point, for a surface that stays mounted between openings. */
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const reset = useCallback(() => { baseline.current = null; setAsking(false) }, [])
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return { asking, markStart, requestClose, keepEditing, discard, reset }
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}
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