export type ScrollAxis = 'x' | 'y';
export declare function isScrollable(el: HTMLElement, axis: ScrollAxis): boolean;
/**
 * Whether `el` can still move in the direction `delta` points, so a scroll that
 * has already bottomed out is passed on instead of being silently absorbed.
 */
export declare function canScrollFurther(el: HTMLElement, delta: number, axis: ScrollAxis): boolean;
/**
 * Nearest scrolling ancestor of `start`, stopping at <body>: the document itself
 * is reachable by the browser's own chaining and needs no help from us.
 */
export declare function findScrollableAncestor(start: HTMLElement | null, axis: ScrollAxis): HTMLElement | null;
export declare function normalizeWheelDelta(event: WheelEvent, viewportSize: number): number;
/**
 * Whether `el` has been scrolled out of view of an ancestor that clips it.
 *
 * This matters only for a teleported dropdown. Hanging off <body>, it is not
 * clipped by the containers its trigger lives in, so once the trigger scrolls
 * out of one the dropdown carries on being painted over whatever now occupies
 * that space — anchored to a control the user can no longer see.
 */
export declare function isClippedByAncestor(el: HTMLElement | null): boolean;