import { RefObject } from 'react';
/**
 * Watches a ref and re-renders when its value changes. Checks once per frame via
 * requestAnimationFrame, which is more efficient than setInterval.
 *
 * @param ref - The ref to watch for changes.
 * @param callback - Optional callback invoked whenever the ref's value changes, receiving the new value.
 * @returns The current value of the ref. The component re-renders whenever the ref's value changes.
 */
export declare const useWatchRef: <T>(ref: RefObject<T> | null | undefined, callback?: (newValue: T) => void) => T | undefined;