import { ListRange } from '@angular/cdk/collections';
import { CdkVirtualScrollViewport } from '@angular/cdk/scrolling';
import { EventEmitter, OnDestroy, OnInit } from '@angular/core';
import * as i0 from "@angular/core";
/**
 * Used for marking the loading state of items
 * within a lazily loaded collection
 *
 * @export
 */
export declare enum VirtualScrollItemStatus {
    /**
     * Initial status of an item within the collection,
     * a placeholder with no content
     */
    initial = "initial",
    /**
     * Item marked as pending to be loaded, a request was sent out,
     * but still no content, item data was not yet received
     */
    pending = "pending",
    /**
     * Item with content, data of item has been loaded
     */
    loaded = "loaded"
}
/**
 * Item with loading state to be used
 * if lazily loading results to reduce events emitted
 * and intervals emitted within events on `rangeLoad` Output
 *
 * @export
 */
export interface VirtualScrollItem {
    loading?: VirtualScrollItemStatus;
}
/**
 * A directive that is designed to work alongside CdkVirtualScrollViewport
 * which can be used to lazy load in chunks depending on what is in view
 *
 * @export
 */
export declare class UiVirtualScrollRangeLoaderDirective implements OnInit, OnDestroy {
    private readonly _viewport;
    /**
     * Used to extend the ListRange interval emmited by rangeLoad Output
     * this will expand at both ends with the specified number,
     * taking into account the status of the loading items
     * available
     *
     */
    buffer: number;
    /**
     * Flag used to indicate the direction of items
     * set to `false` if virtual scroll events indexes need to be reversed
     */
    isDown: boolean;
    /**
     * Output of `ListRange` events based on renderedRangeStream from
     * CdkVirtualScrollViewport which takes into account
     * direction of list (`isDown`), `buffer`
     * and reduces interval to untouched indexes (items with `loading: "initial"`)
     *
     */
    rangeLoad: EventEmitter<ListRange>;
    private readonly _cdkVirtualForOf;
    private readonly _destroyed$;
    /**
     * @ignore
     */
    constructor(_viewport: CdkVirtualScrollViewport);
    /**
     * @ignore
     */
    ngOnInit(): void;
    /**
     * @ignore
     */
    ngOnDestroy(): void;
    private _filterTouchedRange;
    private _isValidRange;
    private _reverseIndex;
    private _adjustLoadingRange;
    private _addSafeBuffer;
    private _trimInterval;
    static ɵfac: i0.ɵɵFactoryDeclaration<UiVirtualScrollRangeLoaderDirective, [{ self: true; }]>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<UiVirtualScrollRangeLoaderDirective, "[uiVirtualScrollRangeLoader], ui-virtual-scroll-range-loader", never, { "buffer": "buffer"; "isDown": "isDown"; }, { "rangeLoad": "rangeLoad"; }, ["_cdkVirtualForOf"], never, false, never>;
}