export type Direction = 'ltr' | 'rtl';
/**
 * How pages group into spreads:
 * - `double`: paired from the start — `[0|1] [2|3] …`
 * - `single`: one page per spread — `[0] [1] …`
 * - `cover`: first page alone, then paired — `[·|0] [1|2] …`
 * - `book`: first AND last alone (front + back cover) — `[·|0] [1|2] … [N-1|·]`
 */
export type SpreadMode = 'double' | 'single' | 'cover' | 'book';
export interface Spread {
    /** Page index shown on the left, or null for a blank side. */
    left: number | null;
    /** Page index shown on the right, or null for a blank side. */
    right: number | null;
}
export interface SpreadOptions {
    direction?: Direction;
    mode?: SpreadMode;
}
/**
 * Map a flat page list (indices 0..pageCount-1) into display spreads.
 *
 * Reading order is always preserved; `direction` only mirrors each spread's
 * left/right positions, so RTL is just an LTR layout with the sides swapped.
 * Out-of-range slots are `null` (a blank half on odd counts / a lone cover).
 */
export declare function buildSpreads(pageCount: number, options?: SpreadOptions): Spread[];
/** Whether a container this wide should fall back to one page per spread. */
export declare function shouldSinglePage(containerWidth: number, threshold: number): boolean;