86 lines
2.1 KiB
TypeScript
Executable file
86 lines
2.1 KiB
TypeScript
Executable file
import { Subscribable } from './subscribable'
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import { isServer } from './utils'
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type Listener = (focused: boolean) => void
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type SetupFn = (
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setFocused: (focused?: boolean) => void,
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) => (() => void) | undefined
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export class FocusManager extends Subscribable<Listener> {
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#focused?: boolean
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#cleanup?: () => void
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#setup: SetupFn
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constructor() {
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super()
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this.#setup = (onFocus) => {
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// addEventListener does not exist in React Native, but window does
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// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
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if (!isServer && window.addEventListener) {
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const listener = () => onFocus()
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// Listen to visibilitychange
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window.addEventListener('visibilitychange', listener, false)
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return () => {
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// Be sure to unsubscribe if a new handler is set
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window.removeEventListener('visibilitychange', listener)
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}
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}
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return
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}
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}
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protected onSubscribe(): void {
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if (!this.#cleanup) {
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this.setEventListener(this.#setup)
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}
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}
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protected onUnsubscribe() {
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if (!this.hasListeners()) {
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this.#cleanup?.()
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this.#cleanup = undefined
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}
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}
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setEventListener(setup: SetupFn): void {
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this.#setup = setup
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this.#cleanup?.()
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this.#cleanup = setup((focused) => {
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if (typeof focused === 'boolean') {
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this.setFocused(focused)
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} else {
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this.onFocus()
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}
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})
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}
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setFocused(focused?: boolean): void {
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const changed = this.#focused !== focused
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if (changed) {
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this.#focused = focused
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this.onFocus()
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}
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}
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onFocus(): void {
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const isFocused = this.isFocused()
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this.listeners.forEach((listener) => {
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listener(isFocused)
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})
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}
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isFocused(): boolean {
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if (typeof this.#focused === 'boolean') {
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return this.#focused
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}
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// document global can be unavailable in react native
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// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
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return globalThis.document?.visibilityState !== 'hidden'
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}
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}
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export const focusManager = new FocusManager()
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