import { AfterViewInit, ElementRef, EventEmitter, OnDestroy } from '@angular/core';
import * as i0 from "@angular/core";
export declare class ViewportIntersectionDirective implements AfterViewInit, OnDestroy {
    private readonly element;
    /**
     * An optional reference to a container element with its own scrollable area. If not provided, the viewport is used as the default container.
     */
    scrollContainer?: HTMLElement | null;
    /**
     * A single number or an array of numbers indicating at what percentage of the target's
     * visibility the observer's callback should be executed.
     * For example, a threshold of 1.0 means the callback will trigger when 100% of the target is visible within the observed area.
     *
     * Please refers to the official documentation of Intersection API for more informations.
     */
    threshold?: number | number[];
    /**
     * A margin around the root element.
     * This margin works like the CSS margin property, setting how much of the root should be seen before the intersection is observed.
     * It's specified in pixels or percentages.
     *
     * Please refers to the official documentation of Intersection API for more informations.
     */
    rootMargin?: string;
    debug: boolean;
    /**
     * This event is emitted whenever the observed element intersects with the viewport or the specified scrollContainer
     * according to the given threshold and rootMargin.
     */
    intersected: EventEmitter<void>;
    private intersectionObserver?;
    constructor(element: ElementRef<HTMLElement>);
    ngAfterViewInit(): void;
    ngOnDestroy(): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<ViewportIntersectionDirective, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<ViewportIntersectionDirective, "[viewportIntersection]", never, { "scrollContainer": { "alias": "scrollContainer"; "required": false; }; "threshold": { "alias": "threshold"; "required": false; }; "rootMargin": { "alias": "rootMargin"; "required": false; }; "debug": { "alias": "debug"; "required": false; }; }, { "intersected": "intersected"; }, never, never, true, never>;
    static ngAcceptInputType_debug: unknown;
}