import { type RefObject } from 'react';
/** Room left between the panel and the edge of the viewport, in screen pixels. */
export declare const VIEW_MARGIN_PX = 8;
/** The custom property the panel reads its vertical shift from. */
export declare const SHIFT_PROPERTY = "--p1-thread-shift";
/**
 * How far to move a panel, in its own CSS pixels, so that it stays inside the window
 * it is drawn in. The panel's natural top is where it would sit unshifted; a panel
 * taller than the window keeps its top in view and lets its bottom go.
 */
export declare function shiftIntoView(naturalTop: number, height: number, viewportHeight: number, scale?: number, margin?: number): number;
/**
 * Keeps an absolutely placed panel inside its window's viewport by writing the shift it
 * needs to a custom property on the element. Written straight to the DOM so a panel
 * riding along with a scroll never re-renders. The intersection observer catches the
 * moves nothing else reports, such as content above the panel reflowing.
 */
export declare function useKeepInView(ref: RefObject<HTMLElement | null>): void;