import type { ItemPosition } from './layout';
import type { ScrollState } from './types';
export interface VisibleRangeParams {
    positions: ItemPosition[];
    /** Measured height per index; holes fall back to `fallbackHeight`. */
    heights: ArrayLike<number | undefined>;
    scroll: ScrollState;
    /** Extra pixels kept rendered above and below the viewport. */
    overscan: number;
    /** Height assumed for unmeasured items. Default: 0 */
    fallbackHeight?: number;
}
/**
 * Determine which item indices intersect the viewport, plus the overscan
 * buffer, in container-relative coordinates.
 *
 * Kept separate from any framework so React, Vue, and the vanilla engine
 * share identical visibility semantics.
 */
export declare function computeVisibleIndices(params: VisibleRangeParams): Set<number>;
/**
 * Decide whether virtualization may take effect yet.
 *
 * Virtualization must not clip items while their heights are still unknown, or
 * the layout would be computed from zeros. Supplying `estimatedItemHeight`
 * provides that missing height up front, which lets large lists skip the
 * render-everything measurement pass entirely.
 */
export declare function canVirtualize(options: {
    virtualize: boolean;
    isMeasured: boolean;
    hasEstimate: boolean;
    itemCount: number;
}): boolean;