import { ElementRef, EmbeddedViewRef, TrackByFunction, ViewContainerRef } from '@angular/core';
import { Observable } from 'rxjs';
import { RxVirtualForViewContext } from './list-view-context';
import * as i0 from "@angular/core";
export interface ListRange {
    start: number;
    end: number;
}
/**
 * @Directive RxVirtualScrollStrategy
 *
 * @description
 * Abstract implementation for the actual implementations of the ScrollStrategies
 * being consumed by `*rxVirtualFor` and `rx-virtual-scroll-viewport`.
 *
 * This is one of the core parts for the virtual scrolling implementation. It has
 * to determine the `ListRange` being rendered to the DOM as well as managing
 * the layouting task for the `*rxVirtualFor` directive.
 *
 * @docsCategory RxVirtualFor
 * @docsPage RxVirtualFor
 * @publicApi
 */
export declare abstract class RxVirtualScrollStrategy<T> {
    /** Emits when the index of the first element visible in the viewport changes. */
    /** @internal */
    abstract scrolledIndex$: Observable<number>;
    /** @internal */
    abstract renderedRange$: Observable<ListRange>;
    /** @internal */
    abstract contentSize$: Observable<number>;
    /** @internal */
    private nodeIndex?;
    /** @internal */
    protected getElement(view: EmbeddedViewRef<RxVirtualForViewContext<T>>): HTMLElement;
    /**
     * Attaches this scroll strategy to a viewport.
     * @param viewport The viewport to attach this strategy to.
     * @param viewRepeater The viewRepeater attached to the viewport.
     */
    abstract attach(viewport: RxVirtualScrollViewport, viewRepeater: RxVirtualViewRepeater<any>): void;
    /** Detaches this scroll strategy from the currently attached viewport. */
    abstract detach(): void;
    /**
     * Scroll to the offset for the given index.
     * @param index The index of the element to scroll to.
     * @param behavior The ScrollBehavior to use when scrolling.
     */
    abstract scrollToIndex(index: number, behavior?: ScrollBehavior): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollStrategy<any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollStrategy<any>, never, never, {}, {}, never>;
}
/** @internal */
export declare abstract class RxVirtualScrollViewport {
    abstract elementScrolled$: Observable<void>;
    abstract containerRect$: Observable<{
        height: number;
        width: number;
    }>;
    abstract getScrollTop(): number;
    abstract scrollToIndex(index: number, behavior?: ScrollBehavior): void;
    abstract scrollTo(scrollTo: number, behavior?: ScrollBehavior): void;
    abstract getScrollElement(): HTMLElement;
    abstract measureOffset(): number;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollViewport, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollViewport, never, never, {}, {}, never>;
}
/** @internal */
export declare abstract class RxVirtualViewRepeater<T> {
    abstract values$: Observable<Array<T> | null | undefined>;
    abstract viewsRendered$: Observable<EmbeddedViewRef<RxVirtualForViewContext<T>>[]>;
    abstract viewContainer: ViewContainerRef;
    abstract renderingStart$: Observable<Set<number>>;
    abstract setScrollStrategy(scrollStrategy: RxVirtualScrollStrategy<T>): any;
    _trackBy: TrackByFunction<T> | null;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualViewRepeater<any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualViewRepeater<any>, never, never, {}, {}, never>;
}
export declare abstract class RxVirtualScrollElement {
    abstract elementScrolled$: Observable<void>;
    abstract getElementRef(): ElementRef<HTMLElement>;
    abstract measureOffset(): number;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollElement, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollElement, never, never, {}, {}, never>;
}