/** Native Canvas2D allocation shared by the secondary layout measurers. */
export type LayoutMeasurementContext = CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D;
type UnavailablePolicy = 'require-native' | 'headless-approximation';
export declare function getLayoutMeasurementFontGeneration(): number;
/** Invalidates secondary caches when a face changes behind an unchanged CSS font string. */
export declare function invalidateLayoutMeasurementFonts(): void;
export declare function createLayoutMeasurementContext(options?: {
    context?: LayoutMeasurementContext;
    ownerDocument?: Document;
    unavailable?: UnavailablePolicy;
}): LayoutMeasurementContext | null;
export {};