import { OnInit, ElementRef, AfterViewInit } from '@angular/core';
/**
 * This directive puts a css class in a sticky element to improve usability.
 * To understand how it works I highly recommend to read the article that was used to made this.
 * Here you can understand better the architecture:
 * https://developers.google.com/web/updates/2017/09/sticky-headers
 */
export declare class StickyDirective implements OnInit, AfterViewInit {
    private stickyElement;
    /**
     * * It must be a top container of the sticky element and of the element that will trigger the custom class on the sticky element.
     * * This should be the element with the scroll
     * If an string is provided, it must be the ID of the element.
     */
    scrollContainer: string | ElementRef | HTMLElement;
    private _scrollContainer;
    /**
     * When the sticky element bypass this element the custom class will apply.
     * If an string is provided, it must be the ID of the element.
     */
    triggerOn: string | ElementRef | HTMLElement;
    private _triggerOn;
    /**
     * When it's on, add some styles to the sentinel element
     */
    debugMode: boolean;
    private _debugMode;
    /**
     * Class to be added to the target element when becomes sticky
     */
    classWhenSticky: string;
    /**
     * zIndex value to set to the target element
     */
    zIndex: number;
    /**
     * Top value to set to the target element
     */
    top: number;
    /**
     * Sentinel element created
     */
    private sentinel;
    constructor(stickyElement: ElementRef);
    ngOnInit(): void;
    ngAfterViewInit(): void;
    /**
     * Transform if needed into HTMLElement a value given to be set in a property
     */
    private setHTMLElement;
    /**
     * Make the main element sticky.
     * Put the necessary css to make it happen.
     */
    private makeSticky;
    private setStylePropertyToElement;
    /**
     * Start listening to the scroll event on the container element
     */
    private setObserver;
    /**
     * Add/Remove class to the target element when the sentinel element disappear/appear
     */
    private onAppears;
    /**
     * Generates the sentinel element with the necessary styles
     */
    private generateSentinelElement;
    /**
     * Add the sentinel element as the first child of the triggerOn element
     */
    private putSentinel;
}