import { ReactiveController, ReactiveControllerHost } from 'lit';
import { SbbElementInternalsMixinType } from '../mixins.ts';
/**
 * Controller for managing overlays positioning. Also acts as a polyfill when native
 * CSS Anchor Positioning is not supported (enough).
 * Applies unique anchor names when using native CSS Anchor Positioning
 * or calculates and applies correct positions in polyfill mode.
 *
 * Also, the controller sets the 'data-position' attribute on the overlay element.
 * This can be used to apply specific styles based on the current position of the overlay.
 *
 * ### Implementation
 * Define and apply the following CSS variables on the overlay element:
 * ```scss
 *   --sbb-overlay-position-area: block-end; // Default
 *   --sbb-overlay-position-try-fallbacks: block-start, inline-end, inline-start; // Fallbacks
 *
 *   position-area: var(--sbb-overlay-position-area);
 *   position-try-fallbacks: var(--sbb-overlay-position-try-fallbacks);
 * ```
 */
export declare class SbbOverlayPositionController implements ReactiveController {
    private _usePolyfill;
    private readonly _resizeObserver;
    private readonly _overlay;
    private _abortController?;
    private _anchor?;
    private _overlayStyles?;
    private _frame?;
    private _anchorName;
    private _positions;
    private _lastPosition?;
    /** Get the current position. (e.g. block-end, block-start, etc.) */
    get currentPosition(): string;
    constructor(host: ReactiveControllerHost & HTMLElement & SbbElementInternalsMixinType, _usePolyfill?: boolean);
    hostConnected(): void;
    hostUpdate(): void;
    /**
     * Connects the overlay to the given trigger element and determines the optimal position.
     * Usually, this is called when the overlay is opened.
     * @param anchor The anchor element.
     */
    connect(anchor: HTMLElement): void;
    disconnect(): void;
    private _requestCalculatePosition;
    private _calculatePosition;
    /**
     * Calculates the optimal position that fits the overlay.
     * @param positions The list of positions to check.
     * @private
     */
    private _getOptimalPosition;
    private _applyOverlayPosition;
    /**
     * Only used in polyfill mode.
     * Reads the list of the configured positions from the CSS variables.
     * @private
     */
    private _readPositionsFromCss;
}
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