/**
 * Two-page spreads (`:::page{spread}`, #567): one split tree laid over the
 * frames of two facing pages joined across the spine (their inner margins
 * dropped), then cut at the spine. Each page carries the panels that reach
 * its side, clipped there (a panel or picture crossing the spine shows on
 * both, each page painting its half), the split lines that lie on it and
 * the balloons whose centre is on it, all on its own sheet.
 *
 * The comic is laid out in spread coordinates: the left page's sheet, with
 * the right page's sheet set against it so that the two trim boxes meet at
 * the spine.
 */
import type { BoundingBox, ResolvedConfig, VDTComicPage } from '../vdt.js';
import type { Resource } from '../types.js';
import { type ComicPageContext } from './layoutPage.js';
import type { ComicPageSource } from './types.js';
/** Whether a comic page asks for a spread (`:::page{spread}`). */
export declare function isComicSpread(source: Pick<ComicPageSource, 'kind' | 'attrs'>): boolean;
/** One page of a spread as the build hands it over. */
export type ComicSpreadPage = Pick<ComicPageContext, 'page' | 'trimBox' | 'bleedBox' | 'mirrorMargins' | 'contentBox'>;
export interface ComicSpreadContext {
    resolved: ResolvedConfig;
    resources: ReadonlyMap<string, Resource>;
    sourceOffset?: number;
    /** The left page and the right page of the open book. */
    left: ComicSpreadPage;
    right: ComicSpreadPage;
}
/** The band about the spine that lettering and text keep out of, on a
 *  half of a spread laid out by {@link layoutComicSpread} (the half of a
 *  gutter 8 mm wide that lies on its sheet, sheet px); undefined for
 *  anything else. */
export declare function comicSpreadGutter(comic: Pick<VDTComicPage, 'spread' | 'frame'>, dpi: number, sheetHeight: number): BoundingBox | undefined;
/**
 * Lay out a spread over two facing pages: `[left, right]`, each on its own
 * sheet. Reading direction, gutters, panel styles and bleed work as on a
 * page; bleeding panels bleed through the outer edges (head, foot, fore
 * edges), never at the spine.
 */
export declare function layoutComicSpread(source: ComicPageSource, given: ComicSpreadContext): [VDTComicPage, VDTComicPage];
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