/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */
import { InjectionToken } from '@angular/core';
import { Observable } from 'rxjs';
import { CdkVirtualScrollViewport } from './virtual-scroll-viewport';
/** The injection token used to specify the virtual scrolling strategy. */
export declare const VIRTUAL_SCROLL_STRATEGY: InjectionToken<VirtualScrollStrategy>;
/** A strategy that dictates which items should be rendered in the viewport. */
export interface VirtualScrollStrategy {
    /** Emits when the index of the first element visible in the viewport changes. */
    scrolledIndexChange: Observable<number>;
    /**
     * Attaches this scroll strategy to a viewport.
     * @param viewport The viewport to attach this strategy to.
     */
    attach(viewport: CdkVirtualScrollViewport): void;
    /** Detaches this scroll strategy from the currently attached viewport. */
    detach(): void;
    /** Called when the viewport is scrolled (debounced using requestAnimationFrame). */
    onContentScrolled(): void;
    /** Called when the length of the data changes. */
    onDataLengthChanged(): void;
    /** Called when the range of items rendered in the DOM has changed. */
    onContentRendered(): void;
    /** Called when the offset of the rendered items changed. */
    onRenderedOffsetChanged(): 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.
     */
    scrollToIndex(index: number, behavior: ScrollBehavior): void;
}