import React from 'react';
export declare function isBoolean(value: any): value is boolean;
export declare function isFunction(value: any): value is Function;
/**
 * Rect
 *
 * @param props
 */
declare const Rect: React.FC<RectProps>;
declare type RectProps = UseRectOptions & {
    children(args: {
        rect: PRect | null;
        ref: React.RefObject<any>;
    }): JSX.Element;
};
declare function useRect<T extends Element = HTMLElement>(nodeRef: React.RefObject<T | undefined | null>, options?: UseRectOptions): null | DOMRect;
declare function useRect<T extends Element = HTMLElement>(nodeRef: React.RefObject<T | undefined | null>, observe?: UseRectOptions['observe'], onChange?: UseRectOptions['onChange']): null | DOMRect;
declare type UseRectOptions = {
    observe?: boolean;
    onChange?: (rect: PRect) => void;
};
declare type PRect = Partial<DOMRect> & {
    readonly bottom: number;
    readonly height: number;
    readonly left: number;
    readonly right: number;
    readonly top: number;
    readonly width: number;
};
export default Rect;
export { Rect, useRect };