import { ScrollStrategy } from './scroll-strategy';
/**
 * Prevents scrolling while the overlay content is shown.
 */
export declare class BlockScrollStrategy extends ScrollStrategy {
    private _initialized;
    private _document;
    private _initialScrollTop;
    private _initialScrollLeft;
    private _sourceElement;
    constructor();
    /**
     * Initializes the strategy. Should be called once
     *
     */
    initialize(document: Document): void;
    /**
     * Attaches the strategy
     * ```typescript
     * settings.scrollStrategy.attach();
     * ```
     */
    attach(): void;
    /**
     * Detaches the strategy
     * ```typescript
     * settings.scrollStrategy.detach();
     * ```
     */
    detach(): void;
    private onScroll;
}