import { NgIterable, OnChanges, OnDestroy, SimpleChanges } from '@angular/core';
import { Observable } from 'rxjs';
import { ListRange, RxVirtualScrollStrategy, RxVirtualScrollViewport, RxVirtualViewRepeater } from '../model';
import * as i0 from "@angular/core";
/**
 * @Directive DynamicSizeVirtualScrollStrategy
 *
 * @description
 *
 * The `DynamicSizeVirtualScrollStrategy` is very similar to the `AutosizeVirtualScrollStrategy`.
 * It positions items based on a function determining its size.
 *
 * @docsCategory RxVirtualFor
 * @docsPage RxVirtualFor
 * @publicApi
 */
export declare class DynamicSizeVirtualScrollStrategy<T, U extends NgIterable<T> = NgIterable<T>> extends RxVirtualScrollStrategy<T, U> implements OnChanges, OnDestroy {
    private readonly defaults?;
    /**
     * @description
     * The amount of items to render upfront in scroll direction
     */
    runwayItems: number;
    /**
     * @description
     * The amount of items to render upfront in reverse scroll direction
     */
    runwayItemsOpposite: number;
    /**
     * @description
     * When enabled, the scroll strategy stops removing views from the viewport,
     * instead it only adds views. This setting can be changed on the fly. Views will be added in both directions
     * according to the user interactions.
     */
    appendOnly: boolean;
    /**
     * @description
     * If this flag is true, the virtual scroll strategy maintains the scrolled item when new data
     * is prepended to the list. This is very useful when implementing a reversed infinite scroller, that prepends
     * data instead of appending it
     */
    keepScrolledIndexOnPrepend: boolean;
    /**
     * @description
     * Function returning the size of an item
     */
    set itemSize(fn: (item: T) => number);
    get itemSize(): (item: T) => number;
    private _itemSizeFn;
    /** @internal */
    private waitForScroll;
    /** @internal */
    private isStable$;
    /** @internal */
    get isStable(): Observable<boolean>;
    /** @internal */
    private viewport;
    /** @internal */
    private viewRepeater;
    /** @internal */
    private readonly _contentSize$;
    /** @internal */
    readonly contentSize$: Observable<number>;
    /** @internal */
    private _contentSize;
    /** @internal */
    private set contentSize(value);
    private get contentSize();
    /** @internal */
    private readonly _renderedRange$;
    /** @internal */
    readonly renderedRange$: Observable<ListRange>;
    /** @internal */
    private _renderedRange;
    /** @internal */
    private set renderedRange(value);
    /** @internal */
    private get renderedRange();
    /** @internal */
    private readonly _scrolledIndex$;
    /** @internal */
    readonly scrolledIndex$: Observable<number>;
    private _scrolledIndex;
    /** @internal */
    private set scrolledIndex(value);
    private get scrolledIndex();
    /** @internal */
    private get contentLength();
    /** @internal */
    private containerSize;
    /** @internal */
    private _virtualItems;
    /** @internal */
    private scrollTop;
    /** @internal */
    private scrollTopWithOutOffset;
    /** @internal */
    private scrollTopAfterOffset;
    /** @internal */
    private viewportOffset;
    /** @internal */
    private direction;
    /** @internal */
    private anchorScrollTop;
    /** @internal */
    private anchorItem;
    /** @internal */
    private lastScreenItem;
    /** @internal */
    private readonly detached$;
    /** @internal */
    private readonly recalculateRange$;
    /** @internal */
    private until$;
    /** @internal */
    ngOnChanges(changes: SimpleChanges): void;
    /** @internal */
    ngOnDestroy(): void;
    /** @internal */
    attach(viewport: RxVirtualScrollViewport, viewRepeater: RxVirtualViewRepeater<T, U>): void;
    /** @internal */
    detach(): void;
    scrollToIndex(index: number, behavior?: ScrollBehavior): void;
    private scrollTo;
    /** @internal */
    private maintainVirtualItems;
    /** @internal */
    private calcRenderedRange;
    /** @internal */
    private positionElements;
    /**
     * @internal
     * heavily inspired by
     *   https://github.com/GoogleChromeLabs/ui-element-samples/blob/gh-pages/infinite-scroller/scripts/infinite-scroll.js
     */
    private calculateAnchoredItem;
    /** @internal */
    private calcInitialPosition;
    /** @internal */
    private calcAnchorScrollTop;
    /** @internal */
    private getItemSize;
    /** @internal */
    private positionElement;
    static ɵfac: i0.ɵɵFactoryDeclaration<DynamicSizeVirtualScrollStrategy<any, any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<DynamicSizeVirtualScrollStrategy<any, any>, "rx-virtual-scroll-viewport[dynamic]", never, { "runwayItems": { "alias": "runwayItems"; "required": false; }; "runwayItemsOpposite": { "alias": "runwayItemsOpposite"; "required": false; }; "appendOnly": { "alias": "appendOnly"; "required": false; }; "keepScrolledIndexOnPrepend": { "alias": "keepScrolledIndexOnPrepend"; "required": false; }; "itemSize": { "alias": "dynamic"; "required": false; }; }, {}, never, never, true, never>;
    static ngAcceptInputType_appendOnly: null | boolean | string | undefined;
    static ngAcceptInputType_keepScrolledIndexOnPrepend: null | boolean | string | undefined;
}