import { NgZone, ElementRef, OnInit, OnDestroy } from '@angular/core';
export declare class DropdownDirective implements OnInit, OnDestroy {
    private _ngZone;
    elementRef: ElementRef;
    private _setMenu;
    private _placement;
    constructor(_ngZone: NgZone, elementRef: ElementRef);
    private _visible;
    private _menu;
    private _popper;
    readonly offsetTop: number;
    ngOnInit(): void;
    ngOnDestroy(): void;
    showDropdown(): void;
    hideDropdown(): void;
    private readonly _clickOutsideEventHandler;
    private readonly _clickEventHandler;
    private _onClickOutside;
    private _onClick;
    private _setVisible;
    private _addPopper;
    private _removePoper;
    private _updateMenuVisibility;
}
export declare type DropdownPlacement = 'auto-start' | 'auto' | 'auto-end' | 'top-start' | 'top' | 'top-end' | 'right-start' | 'right' | 'right-end' | 'bottom-end' | 'bottom' | 'bottom-start' | 'left-end' | 'left' | 'left-start';