/**
 * virtual - a tiny, framework-free fixed-row windowing helper shared by the
 * selection controls so their option lists scale to tens of thousands of rows
 * without rendering them all. The renderer measures the viewport + tracks
 * scrollTop (DOM concerns) and passes them in; this returns the slice to render
 * plus the top/bottom spacer heights that keep the scrollbar honest.
 */
export type VirtualRange = {
    /** First item index to render (inclusive). */
    start: number;
    /** Last item index to render (exclusive). */
    end: number;
    /** Spacer height above the rendered slice (px). */
    padTop: number;
    /** Spacer height below the rendered slice (px). */
    padBottom: number;
    /** Total scrollable height of all rows (px). */
    totalHeight: number;
};
export type VirtualParams = {
    scrollTop: number;
    viewportHeight: number;
    rowHeight: number;
    count: number;
    /** Extra rows rendered above/below the viewport to avoid blank flashes. */
    overscan?: number;
};
/** Compute the visible window for a fixed-row-height list (pure). */
export declare function virtualRange(params: VirtualParams): VirtualRange;
/**
 * The scrollTop that brings item `index` fully into a fixed-row viewport,
 * scrolling the least amount (returns the current scrollTop if already visible).
 * Pure - the renderer applies it to the element.
 */
export declare function scrollToIndex(index: number, scrollTop: number, viewportHeight: number, rowHeight: number): number;