import { Injector, type Signal } from '@angular/core';
import { Observable } from 'rxjs';
export interface InjectDocumentVisibilityOptions {
    document?: Document;
    injector?: Injector;
}
export declare function injectDocumentVisibilityStream(options?: InjectDocumentVisibilityOptions): Observable<DocumentVisibilityState>;
/**
 * Injects and monitors the current document visibility state. Emits the state initially and then emits on every change.
 *
 * This function is useful for scenarios like tracking user presence on a page (e.g., for analytics or pausing/resuming activities) and is adaptable for use with iframes or in testing environments.
 *
 * @example
 * ```ts
 const visibilityState = injectDocumentVisibility();
 effect(() => {
   console.log(this.visibilityState());
 });
 * ```
 *
 * @param options An optional object with the following properties:
 *   - `document`: (Optional) Specifies a custom `Document` instance. This is useful when working with iframes or in testing environments where the global `document` might not be appropriate.
 *   - `injector`: (Optional) Specifies a custom `Injector` instance for dependency injection. This allows for more flexible and testable code by decoupling from a global state or context.
 *
 * @returns A signal that emits the current `DocumentVisibilityState` (`"visible"`, `"hidden"`, etc.) initially and whenever the document visibility state changes.
 */
export declare function injectDocumentVisibility(options?: InjectDocumentVisibilityOptions): Signal<DocumentVisibilityState>;