import type DisplayArea from '../../../types/displayArea.js';
import type { PlanarDisplayArea, PlanarViewState } from './PlanarViewportTypes.js';
export declare function cloneDisplayArea<T extends DisplayArea | PlanarDisplayArea>(displayArea?: T): T | undefined;
export declare function createDefaultPlanarViewState(): PlanarViewState;
export declare function normalizePlanarViewState(viewState: PlanarViewState): PlanarViewState;