import { NgZone } from '@angular/core';
import { SmzViewportConfig } from './models/smz-viewport-config';
import type { InViewportTrigger } from './types';
import * as i0 from "@angular/core";
export declare class SmzViewportService {
    private ngZone;
    get trigger$(): InViewportTrigger;
    private readonly triggerSubject;
    private registry;
    constructor(ngZone: NgZone);
    register(target: Element, config: SmzViewportConfig): void;
    unregister(target: Element, config: SmzViewportConfig): void;
    private emitTrigger;
    private getRootElement;
    private findEntry;
    static ɵfac: i0.ɵɵFactoryDeclaration<SmzViewportService, never>;
    static ɵprov: i0.ɵɵInjectableDeclaration<SmzViewportService>;
}
