import { Observable } from 'rxjs';
import * as i0 from "@angular/core";
export declare class IsInViewportService implements IsInViewportServiceInterface {
    private readonly ngZone;
    private readonly platformId;
    private observerListeners;
    private observerCounts;
    private observer?;
    private createObserver;
    observe(element: Element): Observable<IntersectionObserverEntry>;
    unobserve(element: Element): void;
    private intersect;
    private disconnect;
    static ɵfac: i0.ɵɵFactoryDeclaration<IsInViewportService, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<IsInViewportService>;
}
export interface IsInViewportServiceInterface {
    observe(element: Element): Observable<IntersectionObserverEntry>;
    unobserve(element: Element): void;
}