@rx-angular/template/experimental/virtual-scrolling/index.d.ts

**Fully** Reactive Component Template Rendering in Angular. @rx-angular/template aims to be a reflection of Angular's built in renderings just reactive.

import * as i0 from '@angular/core';
import { NgIterable, EmbeddedViewRef, ViewContainerRef, TrackByFunction, ElementRef, OnChanges, OnDestroy, SimpleChanges, OnInit, DoCheck, Signal, TemplateRef, InjectionToken, AfterViewInit, AfterContentInit } from '@angular/core';
import { RxDefaultListViewContext, RxListViewComputedContext } from '@rx-angular/cdk/template';
import * as rxjs from 'rxjs';
import { Observable, Subject } from 'rxjs';
import { RxStrategyNames } from '@rx-angular/cdk/render-strategies';
import * as _rx_angular_template_experimental_virtual_scrolling from '@rx-angular/template/experimental/virtual-scrolling';

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
 */
declare abstract class RxVirtualScrollStrategy<T, U extends NgIterable<T> = NgIterable<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$: Observable<number>;
    /** @internal */
    get isStable(): Observable<boolean>;
    /**
     * @description
     *
     * Emits whenever an update to a single view was rendered
     */
    readonly viewRenderCallback: Subject<{
        view: EmbeddedViewRef<RxVirtualForViewContext<T, U>>;
        item: T;
        index: number;
    }>;
    /** @internal */
    private nodeIndex?;
    /** @internal */
    protected getElement(view: EmbeddedViewRef<RxVirtualForViewContext<T, U>>): HTMLElement;
    /**
     * Attaches this scroll strategy to a viewport.
     * @param viewport The viewport to attach this strategy to.
     * @param viewRepeater The viewRepeater attached to the viewport.
     */
    abstract attach(viewport: RxVirtualScrollViewport, viewRepeater: RxVirtualViewRepeater<any>): void;
    /** Detaches this scroll strategy from the currently attached viewport. */
    abstract detach(): void;
    /**
     * Scroll to the offset for the given index.
     * @param index The index of the element to scroll to.
     * @param behavior The ScrollBehavior to use when scrolling.
     */
    abstract scrollToIndex(index: number, behavior?: ScrollBehavior): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollStrategy<any, any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollStrategy<any, any>, never, never, {}, {}, never, never, true, never>;
}
/** @internal */
declare abstract class RxVirtualScrollViewport {
    abstract elementScrolled$: Observable<void>;
    abstract containerRect$: Observable<{
        height: number;
        width: number;
    }>;
    abstract getScrollTop(): number;
    abstract scrollTo(scrollTo: number, behavior?: ScrollBehavior): void;
    abstract getScrollElement(): HTMLElement;
    abstract measureOffset(): number;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollViewport, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollViewport, never, never, {}, {}, never, never, true, never>;
}
/** @internal */
declare abstract class RxVirtualViewRepeater<T, U extends NgIterable<T> = NgIterable<T>> {
    abstract values$: Observable<U | null | undefined>;
    abstract viewsRendered$: Observable<EmbeddedViewRef<RxVirtualForViewContext<T, U>>[]>;
    abstract viewRendered$: Observable<{
        view: EmbeddedViewRef<RxVirtualForViewContext<T, U>>;
        index: number;
        item: T;
    }>;
    abstract viewContainer: ViewContainerRef;
    abstract renderingStart$: Observable<Set<number>>;
    _trackBy: TrackByFunction<T> | null;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualViewRepeater<any, any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualViewRepeater<any, any>, never, never, {}, {}, never, never, true, never>;
}
/** @internal */
declare class RxVirtualForViewContext<T, U extends NgIterable<T> = NgIterable<T>, C extends {
    count: number;
    index: number;
} = {
    count: number;
    index: number;
}, K = keyof T> extends RxDefaultListViewContext<T, U, K> {
    rxVirtualForOf: U;
    constructor(item: T, rxVirtualForOf: U, customProps?: C);
}
declare abstract class RxVirtualScrollElement {
    abstract elementScrolled$: Observable<void>;
    abstract getElementRef(): ElementRef<HTMLElement>;
    abstract measureOffset(): number;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollElement, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollElement, never, never, {}, {}, never, never, true, never>;
}

/**
 * @Directive AutosizeVirtualScrollStrategy
 *
 * @description
 *
 * The `AutosizeVirtualScrollStrategy` provides a twitter-like virtual-scrolling
 * experience. It is able to render and position items based on their individual
 * size. It is comparable to \@angular/cdk/experimental `AutosizeVirtualScrollStrategy`, but
 * with a high performant layouting technique and more features.
 *
 * On top of this the `AutosizeVirtualScrollStrategy` is leveraging the native
 * `ResizeObserver` in order to detect size changes for each individual view
 * rendered to the DOM and properly re-position accordingly.
 *
 * In order to provide top-notch runtime performance the `AutosizeVirtualScrollStrategy`
 * builds up caches that prevent DOM interactions whenever possible. Once a view
 * was visited, its properties will be stored instead of re-read from the DOM again as
 * this can potentially lead to unwanted forced reflows.
 *
 * @docsCategory RxVirtualFor
 * @docsPage RxVirtualFor
 * @publicApi
 */
declare class AutoSizeVirtualScrollStrategy<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
     * The default size of the items being rendered. The autosized strategy will assume
     * this size for items it doesn't know yet. For the smoothest experience,
     * you provide the mean size of all items being rendered - if possible of course.
     *
     * As soon as rxVirtualFor is able to also render actual tombstone items, this
     * will be the size of a tombstone item being rendered before the actual item
     * is inserted into its position.
     */
    tombstoneSize: number;
    /**
     * @description
     * The autosized strategy uses the native ResizeObserver in order to determine
     * if an item changed in size to afterwards properly position the views.
     * You can customize the config passed to the ResizeObserver as well as determine
     * which result property to use when determining the views size.
     */
    resizeObserverConfig?: {
        options?: ResizeObserverOptions;
        extractSize?: (entry: ResizeObserverEntry) => number;
    };
    /**
     * @description
     * When enabled, the autosized scroll strategy attaches a `ResizeObserver`
     * to every view within the given renderedRange. If your views receive
     * dimension changes that are not caused by list updates, this is a way to
     * still track height changes. This also applies to resize events of the whole
     * document.
     */
    withResizeObserver: boolean;
    /**
     * @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
     * When enabled, the autosized scroll strategy removes css styles that
     * prevent the scrollbar from being in sync with the input device.
     * Use with caution, as this can lead to extremely weird scroll behavior
     * on chromium based browsers when the rendered views differ
     * in dimensions too much or change dimensions heavily.
     */
    withSyncScrollbar: 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;
    /** @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 positionedRange;
    /** @internal */
    private readonly _scrolledIndex$;
    /** @internal */
    readonly scrolledIndex$: Observable<number>;
    /**
     * @internal
     * The action used to kick off the scroll process
     */
    private scrollToTrigger$;
    /** @internal */
    private _scrolledIndex;
    /** @internal */
    private get scrolledIndex();
    /** @internal */
    private set scrolledIndex(value);
    /**
     * is set, when scrollToIndex is called
     * @internal
     * */
    private _scrollToIndex;
    /** @internal */
    private containerSize;
    /** @internal */
    private contentLength;
    /** @internal */
    private _virtualItems;
    /** @internal */
    private scrollTop;
    /** @internal */
    private scrollTopWithOutOffset;
    /** @internal */
    private scrollTopAfterOffset;
    /** @internal */
    private viewportOffset;
    /** @internal */
    private direction;
    /** @internal */
    private anchorScrollTop;
    /** @internal */
    private anchorItem;
    /** @internal */
    private lastScreenItem;
    /** @internal */
    private waitForScroll;
    /** @internal */
    private isStable$;
    /** @internal */
    private readonly detached$;
    /** @internal */
    private resizeObserver;
    /** @internal */
    private readonly recalculateRange$;
    /** @internal */
    private until$;
    /** @internal */
    private get extractSize();
    /** @internal */
    get isStable(): Observable<boolean>;
    /** @internal */
    ngOnChanges(changes: SimpleChanges): void;
    /** @internal */
    ngOnDestroy(): void;
    /** @internal */
    attach(viewport: RxVirtualScrollViewport, viewRepeater: RxVirtualViewRepeater<T, U>): void;
    /** @internal */
    detach(): void;
    scrollToIndex(index: number, behavior?: ScrollBehavior): void;
    private scrollTo;
    /**
     * starts the subscriptions that maintain the virtualItems array on changes
     * to the underlying dataset
     * @internal
     */
    private maintainVirtualItems;
    /**
     * listen to triggers that should change the renderedRange
     * @internal
     */
    private calcRenderedRange;
    /**
     * position elements after they are created/updated/moved or their dimensions
     * change from other sources
     * @internal
     */
    private positionElements;
    /** listen to API initiated scroll triggers (e.g. initialScrollIndex) */
    private listenToScrollTrigger;
    /** @internal */
    private adjustContentSize;
    /** @internal */
    private observeViewSize$;
    /**
     * @internal
     * heavily inspired by
     *   https://github.com/GoogleChromeLabs/ui-element-samples/blob/gh-pages/infinite-scroller/scripts/infinite-scroll.js
     */
    private calculateAnchoredItem;
    /** @internal */
    private positionUnchangedViews;
    /**
     * Adjust the scroll position when the anchorScrollTop differs from
     * the actual scrollTop.
     * Trigger a range recalculation if there is empty space
     *
     * @internal
     */
    private maybeAdjustScrollPosition;
    /** @internal */
    private calcAnchorScrollTop;
    /** @internal */
    private calcInitialPosition;
    /** @internal */
    private getViewRef;
    /** @internal */
    private updateElementSize;
    /** @internal */
    private getItemSize;
    /** @internal */
    private getElementSize;
    /** @internal */
    private positionElement;
    /** @internal */
    private updateScrollElementClass;
    static ɵfac: i0.ɵɵFactoryDeclaration<AutoSizeVirtualScrollStrategy<any, any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<AutoSizeVirtualScrollStrategy<any, any>, "rx-virtual-scroll-viewport[autosize]", never, { "runwayItems": { "alias": "runwayItems"; "required": false; }; "runwayItemsOpposite": { "alias": "runwayItemsOpposite"; "required": false; }; "tombstoneSize": { "alias": "tombstoneSize"; "required": false; }; "resizeObserverConfig": { "alias": "resizeObserverConfig"; "required": false; }; "withResizeObserver": { "alias": "withResizeObserver"; "required": false; }; "appendOnly": { "alias": "appendOnly"; "required": false; }; "withSyncScrollbar": { "alias": "withSyncScrollbar"; "required": false; }; "keepScrolledIndexOnPrepend": { "alias": "keepScrolledIndexOnPrepend"; "required": false; }; }, {}, never, never, true, never>;
    static ngAcceptInputType_withResizeObserver: null | boolean | string | undefined;
    static ngAcceptInputType_appendOnly: null | boolean | string | undefined;
    static ngAcceptInputType_withSyncScrollbar: null | boolean | string | undefined;
    static ngAcceptInputType_keepScrolledIndexOnPrepend: null | boolean | string | undefined;
}

/**
 * @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
 */
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;
}

/**
 * @Directive FixedSizeVirtualScrollStrategy
 *
 * @description
 *
 * The `FixedSizeVirtualScrollStrategy` provides a very performant way of rendering
 * items of a given size. It is comparable to \@angular/cdk `FixedSizeVirtualScrollStrategy`, but
 * with a high performant layouting technique.
 *
 * @docsCategory RxVirtualFor
 * @docsPage RxVirtualFor
 * @publicApi
 */
declare class FixedSizeVirtualScrollStrategy<T, U extends NgIterable<T> = NgIterable<T>> extends RxVirtualScrollStrategy<T, U> implements OnChanges, OnDestroy {
    private readonly defaults?;
    /**
     * @description
     * The size of the items in the virtually scrolled list
     */
    set itemSize(itemSize: number);
    get itemSize(): number;
    private _itemSize;
    /**
     * @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
     * 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
     * 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;
    /** @internal */
    private readonly runwayStateChanged$;
    private viewport;
    private viewRepeater;
    private readonly _scrolledIndex$;
    readonly scrolledIndex$: rxjs.Observable<number>;
    private _scrolledIndex;
    private set scrolledIndex(value);
    private get scrolledIndex();
    private readonly _contentSize$;
    readonly contentSize$: rxjs.Observable<number>;
    private _contentSize;
    private set contentSize(value);
    private readonly _renderedRange$;
    renderedRange$: rxjs.Observable<ListRange>;
    private _renderedRange;
    private set renderedRange(value);
    private get renderedRange();
    private scrollTop;
    /** @internal */
    private scrollTopWithOutOffset;
    /** @internal */
    private scrollTopAfterOffset;
    /** @internal */
    private viewportOffset;
    /** @internal */
    private containerSize;
    private direction;
    private readonly detached$;
    /** @internal */
    ngOnChanges(changes: SimpleChanges): void;
    ngOnDestroy(): void;
    attach(viewport: RxVirtualScrollViewport, viewRepeater: RxVirtualViewRepeater<T, U>): void;
    detach(): void;
    private positionElements;
    private calcRenderedRange;
    scrollToIndex(index: number, behavior?: ScrollBehavior): void;
    private untilDetached$;
    private _setViewPosition;
    static ɵfac: i0.ɵɵFactoryDeclaration<FixedSizeVirtualScrollStrategy<any, any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<FixedSizeVirtualScrollStrategy<any, any>, "rx-virtual-scroll-viewport[itemSize]", never, { "itemSize": { "alias": "itemSize"; "required": false; }; "appendOnly": { "alias": "appendOnly"; "required": false; }; "runwayItems": { "alias": "runwayItems"; "required": false; }; "runwayItemsOpposite": { "alias": "runwayItemsOpposite"; "required": false; }; "keepScrolledIndexOnPrepend": { "alias": "keepScrolledIndexOnPrepend"; "required": false; }; }, {}, never, never, true, never>;
    static ngAcceptInputType_appendOnly: null | boolean | string | undefined;
    static ngAcceptInputType_keepScrolledIndexOnPrepend: null | boolean | string | undefined;
}

/**
 * @Directive RxVirtualFor
 *
 * @description
 *
 * The `*rxVirtualFor` structural directive provides a convenient and performant
 * way for rendering huge lists of items. It brings all the benefits `rxFor` does,
 * and implements virtual rendering.
 *
 * Instead of rendering every item provided, rxVirtualFor only renders what is
 * currently visible to the user, thus providing excellent runtime performance
 * for huge sets of data.
 *
 * The technique to render items is comparable to the on used by twitter and
 * explained in very much detail by @DasSurma in his blog post about the [complexities
 * of infinite scrollers](https://developer.chrome.com/blog/infinite-scroller/).
 *
 * "Each recycling of a DOM element would normally relayout the entire runway which
 * would bring us well below our target of 60 frames per second.
 * To avoid this, we are taking the burden of layout onto ourselves and use
 * absolutely positioned elements with transforms." (@DasSurma)
 *
 * ## API
 * The API is a combination of \@rx-angular/template/for &
 *  \@angular/cdk `*cdkVirtualFor`.
 * * trackBy: `(index: number, item: T) => any` | `keyof T`
 * * strategy: `string` | `Observable<string>`
 * * parent: `boolean`;
 * * renderCallback: `Subject<T[]>`
 * * viewCache: `number`
 * * (Injected) scrollStrategy: `RxVirtualScrollStrategy<T, U>`
 * * provides itself as RxVirtualViewRepeater for RxVirtualViewPortComponent to operate
 *
 * ## Features
 * * Push based architecture
 * * Comprehensive set of context variables
 * * Opt-out of `NgZone` with `patchZone`
 * * Notify when rendering of child templates is finished (`renderCallback`)
 * * Super efficient layouting with css transformations
 * * Define a viewCache in order to re-use views instead of re-creating them
 * * Configurable RxVirtualScrollStrategy<T, U> providing the core logic to calculate the viewRange and position DOM
 * Nodes
 *
 * ### Context Variables
 *
 * The following context variables are available for each template:
 *
 * - $implicit: `T` // the default variable accessed by `let val`
 * - item$: `Observable<T>` // the same value as $implicit, but as `Observable`
 * - index: `number` // current index of the item
 * - count: `number` // count of all items in the list
 * - first: `boolean` // true if the item is the first in the list
 * - last: `boolean` // true if the item is the last in the list
 * - even: `boolean` // true if the item has on even index (index % 2 === 0)
 * - odd: `boolean` // the opposite of even
 * - index$: `Observable<number>` // index as `Observable`
 * - count$: `Observable<number>` // count as `Observable`
 * - first$: `Observable<boolean>` // first as `Observable`
 * - last$: `Observable<boolean>` // last as `Observable`
 * - even$: `Observable<boolean>` // even as `Observable`
 * - odd$: `Observable<boolean>` // odd as `Observable`
 * - select: `(keys: (keyof T)[], distinctByMap) => Observable<Partial<T>>`
 * // returns a selection function which
 * // accepts an array of properties to pluck out of every list item. The function returns the selected properties of
 * // the current list item as distinct `Observable` key-value-pair. See the example below:
 *
 * This example showcases the `select` view-context function used for deeply nested lists.
 *
 *  ```html
 * <rx-virtual-scroll-viewport>
 *   <div
 *    autosized
 *    *rxVirtualFor="let hero of heroes$; trackBy: trackItem; let select = select;">
 *     <div>
 *       <strong>{{ hero.name }}</strong></br>
 *       Defeated enemies:
 *     </div>
 *      <span *rxFor="let enemy of select(['defeatedEnemies']); trackBy: trackEnemy;">
 *        {{ enemy.name }}
 *      </span>
 *   </div>
 * </rx-virtual-scroll-viewport>
 *  ```
 *
 * ### Using the context variables
 *
 * ```html
 * <rx-virtual-scroll-viewport>
 *  <div
 *     *rxVirtualFor="
 *       let item of observableItems$;
 *       let count = count;
 *       let index = index;
 *       let first = first;
 *       let last = last;
 *       let even = even;
 *       let odd = odd;
 *       trackBy: trackItem;
 *     "
 *   >
 *     <div>{{ count }}</div>
 *     <div>{{ index }}</div>
 *     <div>{{ item }}</div>
 *     <div>{{ first }}</div>
 *     <div>{{ last }}</div>
 *     <div>{{ even }}</div>
 *     <div>{{ odd }}</div>
 *   </div>
 * </rx-virtual-scroll-viewport>
 * ```
 *
 * @docsCategory RxVirtualFor
 * @docsPage RxVirtualFor
 * @publicApi
 */
declare class RxVirtualFor<T, U extends NgIterable<T> = NgIterable<T>> implements RxVirtualViewRepeater<T>, OnInit, DoCheck, OnDestroy {
    private readonly templateRef;
    private readonly scrollStrategy;
    private readonly iterableDiffers;
    private readonly cdRef;
    private readonly ngZone;
    /** @internal */
    private injector;
    readonly viewContainer: ViewContainerRef;
    private readonly strategyProvider;
    private readonly errorHandler;
    private readonly defaults?;
    /** @internal */
    private _differ?;
    /** @internal */
    private partiallyFinished;
    /** @internal */
    private staticValue?;
    /** @internal */
    private renderStatic;
    /**
     * @description
     * The iterable input
     *
     * @example
     * <rx-virtual-scroll-viewport>
     *   <app-hero *rxVirtualFor="heroes$; let hero"
     *     [hero]="hero"></app-hero>
     * </rx-virtual-scroll-viewport>
     *
     * @param potentialSignalOrObservable
     */
    set rxVirtualForOf(potentialSignalOrObservable: Observable<(U & NgIterable<T>) | undefined | null> | Signal<(U & NgIterable<T>) | undefined | null> | (U & NgIterable<T>) | null | undefined);
    /**
     * @internal
     * A reference to the template that is created for each item in the iterable.
     * @see [template reference variable](guide/template-reference-variables)
     * (inspired by @angular/common `ng_for_of.ts`)
     */
    private _template?;
    set rxVirtualForTemplate(value: TemplateRef<RxVirtualForViewContext<T, U>>);
    /** @internal */
    private strategyHandler;
    /**
     * @description
     * The rendering strategy to be used to render updates to the DOM.
     * Use it to dynamically manage your rendering strategy. You can switch the strategy
     * imperatively (with a string) or by binding an Observable.
     * The default strategy is `'normal'` if not configured otherwise.
     *
     * @example
     * \@Component({
     *   selector: 'app-root',
     *   template: `
     *     <rx-virtual-scroll-viewport>
     *       <app-hero
     *        autosized
     *        *rxVirtualFor="let hero of heroes$; strategy: strategy"
     *        [hero]="hero"></app-hero>
     *     </rx-virtual-scroll-viewport>
     *   `
     * })
     * export class AppComponent {
     *   strategy = 'low';
     * }
     *
     * // OR
     *
     * \@Component({
     *   selector: 'app-root',
     *   template: `
     *     <rx-virtual-scroll-viewport>
     *       <app-hero
     *        autosized
     *        *rxVirtualFor="let hero of heroes$; strategy: strategy$"
     *        [hero]="hero"></app-hero>
     *     </rx-virtual-scroll-viewport>
     *   `
     * })
     * export class AppComponent {
     *   strategy$ = new BehaviorSubject('immediate');
     * }
     *
     * @param strategyName
     * @see {@link strategies}
     */
    set strategy(strategyName: RxStrategyNames<string> | Observable<RxStrategyNames<string>>);
    /**
     * @description
     * Controls the amount if views held in cache for later re-use when a user is
     * scrolling the list. If this is set to 0, `rxVirtualFor` won't cache any view,
     * thus destroying & re-creating very often on scroll events.
     */
    templateCacheSize: number;
    /**
     * @description
     *  If `parent` is set to `true` (default to `false`), `*rxVirtualFor` will
     *  automatically run change-detection for its parent component when its scheduled
     *  tasks are done in order to update any pending `@ContentChild` or `@ViewChild`
     *  relation to be updated according to the updated ViewContainer.
     *
     * @example
     * \@Component({
     *   selector: 'app-root',
     *   template: `
     *   <rx-virtual-scroll-viewport>
     *      <app-list-item
     *        *rxVirtualFor="
     *          let item of items$;
     *          trackBy: trackItem;
     *          parent: true;
     *        "
     *        [item]="item"
     *        autosized
     *      ></app-list-item>
     *    </rx-virtual-scroll-viewport>
     *   `
     * })
     * export class AppComponent {
     *   // those queries won't be in sync with what `rxVirtualFor` is rendering
     *   // when parent is set to false.
     *   \@ViewChildren(AppListItem) listItems: QueryList<AppListItem>;
     *
     *   items$ = itemService.getItems();
     * }
     *
     * @param renderParent
     *
     * @deprecated this flag will be dropped soon, as it is no longer required when using signal based view & content queries
     */
    renderParent: boolean;
    /**
     * @description
     * A flag to control whether `*rxVirtualFor` rendering happens within
     * `NgZone` or not. The default value is set to `true` if not configured otherwise.
     * If `patchZone` is set to `false` `*rxVirtualFor` will operate completely outside of `NgZone`.
     *
     * @example
     * \@Component({
     *   selector: 'app-root',
     *   template: `
     *    <rx-virtual-scroll-viewport>
     *      <app-list-item
     *        *rxVirtualFor="
     *          let item of items$;
     *          trackBy: trackItem;
     *          patchZone: false;
     *        "
     *        [item]="item"
     *        autosized
     *      ></app-list-item>
     *    </rx-virtual-scroll-viewport>
     *   `
     * })
     * export class AppComponent {
     *   items$ = itemService.getItems();
     * }
     *
     * @param patchZone
     */
    patchZone: boolean;
    /**
     * @description
     * A function or key that defines how to track changes for items in the provided
     * iterable data.
     *
     * When items are added, moved, or removed in the iterable,
     * the directive must re-render the appropriate DOM nodes.
     * To minimize operations on the DOM, only nodes that have changed
     * are re-rendered.
     *
     * By default, `rxVirtualFor` assumes that the object instance identifies
     * the node in the iterable (equality check `===`).
     * When a function or key is supplied, `rxVirtualFor` uses the result to identify the item node.
     *
     * @example
     * \@Component({
     *   selector: 'app-root',
     *   template: `
     *    <rx-virtual-scroll-viewport>
     *      <app-list-item
     *        *rxVirtualFor="
     *          let item of items$;
     *          trackBy: 'id';
     *        "
     *        autosized
     *        [item]="item"
     *      >
     *      </app-list-item>
     *    </rx-virtual-scroll-viewport>
     *   `
     * })
     * export class AppComponent {
     *   items$ = itemService.getItems();
     * }
     *
     * // OR
     *
     * \@Component({
     *   selector: 'app-root',
     *   template: `
     *   <rx-virtual-scroll-viewport>
     *      <app-list-item
     *        *rxVirtualFor="
     *          let item of items$;
     *          trackBy: trackItem;
     *        "
     *        autosized
     *        [item]="item"
     *      >
     *      </app-list-item>
     *    </rx-virtual-scroll-viewport>
     *   `
     * })
     * export class AppComponent {
     *   items$ = itemService.getItems();
     *   trackItem = (idx, item) => item.id;
     * }
     *
     * @param trackByFnOrKey
     */
    set trackBy(trackByFnOrKey: keyof T | TrackByFunction<T>);
    /**
     * @description
     * A `Subject` which emits whenever `*rxVirtualFor` finished rendering a
     * set of changes to the view.
     * This enables developers to perform actions exactly at the timing when the
     * updates passed are rendered to the DOM.
     * The `renderCallback` is useful in situations where you rely on specific DOM
     * properties like the `height` of a table after all items got rendered.
     * It is also possible to use the renderCallback in order to determine if a
     * view should be visible or not. This way developers can hide a list as
     * long as it has not finished rendering.
     *
     * The result of the `renderCallback` will contain the currently rendered set
     * of items in the iterable.
     *
     * @example
     * \@Component({
     *   selector: 'app-root',
     *   template: `
     *    <rx-virtual-scroll-viewport>
     *      <app-list-item
     *        *rxVirtualFor="
     *          let item of items$;
     *          trackBy: trackItem;
     *          renderCallback: itemsRendered;
     *        "
     *        autosized
     *        [item]="item"
     *      >
     *      </app-list-item>
     *    </rx-virtual-scroll-viewport>
     *   `
     * })
     * export class AppComponent {
     *   items$: Observable<Item[]> = itemService.getItems();
     *   trackItem = (idx, item) => item.id;
     *   // this emits whenever rxVirtualFor finished rendering changes
     *   itemsRendered = new Subject<Item[]>();
     * }
     *
     * @param renderCallback
     */
    set renderCallback(renderCallback: Subject<U>);
    /** @internal */
    readonly viewsRendered$: Subject<EmbeddedViewRef<RxVirtualForViewContext<T, U, RxListViewComputedContext, keyof T>>[]>;
    /** @internal */
    readonly viewRendered$: Subject<{
        view: EmbeddedViewRef<RxVirtualForViewContext<T, U>>;
        index: number;
        item: T;
    }>;
    /** @internal */
    readonly renderingStart$: Subject<Set<number>>;
    /** @internal */
    private get template();
    /** @internal */
    private observables$;
    /** @internal */
    private _renderCallback?;
    /** @internal */
    readonly values$: Observable<NgIterable<T>>;
    /** @internal */
    private values?;
    /** @internal */
    private templateManager;
    /** @internal */
    private _destroy$;
    /** @internal */
    _trackBy: TrackByFunction<T> | null;
    /** @internal */
    static ngTemplateContextGuard<T, U extends NgIterable<T> = NgIterable<T>, K = keyof T>(dir: RxVirtualFor<T, U>, ctx: any): ctx is RxVirtualForViewContext<T, U, RxListViewComputedContext, K>;
    constructor(templateRef: TemplateRef<RxVirtualForViewContext<T, U>>);
    /** @internal */
    ngOnInit(): void;
    /** @internal */
    ngDoCheck(): void;
    /** @internal */
    ngOnDestroy(): void;
    private render;
    private handleError;
    private getDiffer;
    /** @internal */
    private createViewContext;
    /** @internal */
    private updateViewContext;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualFor<any, any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualFor<any, any>, "[rxVirtualFor][rxVirtualForOf]", never, { "rxVirtualForOf": { "alias": "rxVirtualForOf"; "required": false; }; "rxVirtualForTemplate": { "alias": "rxVirtualForTemplate"; "required": false; }; "strategy": { "alias": "rxVirtualForStrategy"; "required": false; }; "templateCacheSize": { "alias": "rxVirtualForTemplateCacheSize"; "required": false; }; "renderParent": { "alias": "rxVirtualForParent"; "required": false; }; "patchZone": { "alias": "rxVirtualForPatchZone"; "required": false; }; "trackBy": { "alias": "rxVirtualForTrackBy"; "required": false; }; "renderCallback": { "alias": "rxVirtualForRenderCallback"; "required": false; }; }, {}, never, never, true, never>;
}

interface RxVirtualScrollDefaultOptions {
    templateCacheSize?: number;
    runwayItems?: number;
    runwayItemsOpposite?: number;
    itemSize?: number;
}
/** Injection token to be used to override the default options. */
declare const RX_VIRTUAL_SCROLL_DEFAULT_OPTIONS: InjectionToken<RxVirtualScrollDefaultOptions>;
/** @internal */
declare function RX_VIRTUAL_SCROLL_DEFAULT_OPTIONS_FACTORY(): RxVirtualScrollDefaultOptions;

declare class RxVirtualScrollElementDirective implements RxVirtualScrollElement {
    private readonly elementRef;
    readonly elementScrolled$: rxjs.Observable<void>;
    getElementRef(): ElementRef<HTMLElement>;
    measureOffset(): number;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollElementDirective, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollElementDirective, "[rxVirtualScrollElement]", never, {}, {}, never, never, true, never>;
}

/**
 * @Component RxVirtualScrollViewport
 *
 * @description
 * Container component comparable to CdkVirtualScrollViewport acting as viewport
 * for `*rxVirtualFor` to operate on.
 *
 * Its main purpose is to implement the `RxVirtualScrollViewport` interface
 * as well as maintaining the scroll runways' height in order to give
 * the provided `RxVirtualScrollStrategy` room to position items.
 *
 * Furthermore, it will gather and forward all events to the consumer of `rxVirtualFor`.
 *
 * @docsCategory RxVirtualFor
 * @docsPage RxVirtualFor
 * @publicApi
 */
declare class RxVirtualScrollViewportComponent implements RxVirtualScrollViewport, AfterViewInit, AfterContentInit, OnDestroy {
    private elementRef;
    private scrollStrategy;
    protected scrollElement: RxVirtualScrollElement;
    /**
     * @description
     *
     * Sets the first view to be visible to the user.
     * The viewport waits for the data to arrive and scrolls to the given index immediately.
     *
     * */
    initialScrollIndex: number;
    /** @internal */
    private scrollSentinel;
    /** @internal */
    private runway;
    /** @internal */
    viewRepeater: RxVirtualViewRepeater<unknown>;
    readonly elementScrolled$: rxjs.Observable<void>;
    /** @internal */
    private _containerRect$;
    readonly containerRect$: rxjs.Observable<{
        width: number;
        height: number;
    }>;
    /**
     * @description
     *
     * The range to be rendered by `*rxVirtualFor`. This value is determined by the
     * provided `RxVirtualScrollStrategy`. It gives the user information about the
     * range of items being actually rendered to the DOM.
     * Note this value updates before the `renderCallback` kicks in, thus it is only
     * in sync with the DOM when the next `renderCallback` emitted an event.
     */
    readonly viewRange: rxjs.Observable<_rx_angular_template_experimental_virtual_scrolling.ListRange>;
    /**
     * @description
     *
     * The index of the currently scrolled item. The scrolled item is the topmost
     * item actually being visible to the user.
     */
    readonly scrolledIndexChange: rxjs.Observable<number>;
    /** @internal */
    private readonly destroy$;
    /** @internal */
    constructor();
    ngAfterViewInit(): void;
    /** @internal */
    ngAfterContentInit(): void;
    /** @internal */
    ngOnDestroy(): void;
    getScrollElement(): HTMLElement;
    getScrollTop(): number;
    scrollTo(position: number, behavior?: ScrollBehavior): void;
    scrollToIndex(index: number, behavior?: ScrollBehavior): void;
    measureOffset(): number;
    protected updateContentSize(size: number): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollViewportComponent, never>;
    static ɵcmp: i0.ɵɵComponentDeclaration<RxVirtualScrollViewportComponent, "rx-virtual-scroll-viewport", never, { "initialScrollIndex": { "alias": "initialScrollIndex"; "required": false; }; }, { "viewRange": "viewRange"; "scrolledIndexChange": "scrolledIndexChange"; }, ["viewRepeater"], ["*"], true, never>;
}

declare class RxVirtualScrollWindowDirective implements RxVirtualScrollElement {
    private readonly document;
    private readonly elementRef;
    readonly elementScrolled$: rxjs.Observable<void>;
    getElementRef(): ElementRef<HTMLElement>;
    measureOffset(): number;
    static ɵfac: i0.ɵɵFactoryDeclaration<RxVirtualScrollWindowDirective, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<RxVirtualScrollWindowDirective, "rx-virtual-scroll-viewport[scrollWindow]", never, {}, {}, never, never, true, never>;
}

export { AutoSizeVirtualScrollStrategy, DynamicSizeVirtualScrollStrategy, FixedSizeVirtualScrollStrategy, RX_VIRTUAL_SCROLL_DEFAULT_OPTIONS, RX_VIRTUAL_SCROLL_DEFAULT_OPTIONS_FACTORY, RxVirtualFor, RxVirtualForViewContext, RxVirtualScrollElement, RxVirtualScrollElementDirective, RxVirtualScrollStrategy, RxVirtualScrollViewport, RxVirtualScrollViewportComponent, RxVirtualScrollWindowDirective, RxVirtualViewRepeater };
export type { ListRange, RxVirtualScrollDefaultOptions };