/**
 * Start and end edges of a placement (#936): `top-start`, `start`,
 * `bottom-start`, their `end` counterparts and `align-start` /
 * `align-end`, read on the side the page's lines start from. A template's
 * decoration and running heads are laid on the sheet, where that side is
 * the right of a right-to-left page (and of a vertical one, whose lines
 * follow each other from the right); its frames are laid in the page's
 * flow frame, already mirrored or turned, where it is always the left. So
 * one element written `top-start` stands by the title frame in every
 * edition.
 *
 * With such an edge the offset's `x` runs from the start side to the end
 * side: on a page that starts on the right a positive `x` moves the
 * element left, so the element is the mirror image of the left-to-right
 * one.
 */
import type { AnchorEdge, ElementPlacement } from '../types.js';
/** Whether `edge` is a start or end edge. */
export declare function isLogicalEdge(edge: string): boolean;
/** The physical edge `edge` names when the start is on the right
 *  (`startRight`) or on the left; any other edge unchanged. */
export declare function physicalEdge(edge: AnchorEdge, startRight: boolean): AnchorEdge;
/** `placement` with a start or end edge turned into the physical one, the
 *  offset's `x` reversed when the start is on the right; any other
 *  placement as it is. */
export declare function physicalPlacement<P extends ElementPlacement>(placement: P, startRight: boolean): P;
/** The side `edge` (a physical one, see {@link physicalEdge}) stands on, or
 *  undefined for `center`. */
export declare function edgeSide(edge: AnchorEdge): 'top' | 'bottom' | 'left' | 'right' | undefined;
/** A point along a side as a fraction from its start (`'start'` 0,
 *  `'center'` ½, `'end'` 1, a number held between 0 and 1), or undefined
 *  for anything else. */
export declare function sideFraction(at: unknown): number | undefined;
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