import { ElementRef, OnInit, OnDestroy } from '@angular/core';
import { ScrollSpyService } from './scroll-spy.service';
import * as i0 from "@angular/core";
/**
 * Adds this element as spy-target and starts to observe this target.
 *
 * Automatically removes this element as spy-target and stops observing this target when the element is destroyed.
 */
export declare class SpyTargetDirective implements OnInit, OnDestroy {
    private elementRef;
    private scrollSpyService;
    private platformId;
    /**
     * ID for this spyTarget.
     */
    spyTargetId: string;
    /**
     * @optional
     *
     * ID for the spyTargetContainer containing this spyTarget.
     */
    spyTargetContainerId?: string;
    private target;
    constructor(elementRef: ElementRef<Element>, scrollSpyService: ScrollSpyService, platformId: string);
    ngOnInit(): void;
    ngOnDestroy(): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<SpyTargetDirective, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<SpyTargetDirective, "[spyTarget]", never, { "spyTargetId": "spyTargetId"; "spyTargetContainerId": "spyTargetContainerId"; }, {}, never, never, true>;
}