/**
 * Owns the body-level backdrop lifecycle for every drawer direction.
 * Keeping the portal in one controller prevents side and bottom presentations
 * from developing separate interaction and animation rules.
 */
export default class SlidingContainerBackdrop {
    /**
     * @param {HTMLElement} host Element that supplies tokens, state, and event handlers.
     */
    constructor(host: HTMLElement);
    host: HTMLElement;
    portalElement: HTMLDivElement;
    animation: Animation;
    /**
     * Returns whether an event target belongs to this backdrop.
     * @param {EventTarget|null} element Event target.
     * @returns {boolean} True for the shadow style source or body portal.
     */
    owns(element: EventTarget | null): boolean;
    /**
     * Returns the portal and optionally creates it.
     * @param {object} options Lookup options.
     * @param {boolean} options.create Create the portal when missing.
     * @returns {HTMLElement|null} Backdrop portal.
     */
    get({ create }?: {
        create: boolean;
    }): HTMLElement | null;
    /**
     * Creates the single viewport backdrop used by every presentation.
     * @returns {HTMLElement|null} Backdrop portal.
     */
    ensure(): HTMLElement | null;
    /**
     * Removes the portal and all listeners owned by it.
     */
    remove(): void;
    /**
     * Adds scroll blocking and optional dismiss interactions.
     */
    addListeners(): void;
    /**
     * Removes every listener that may have been attached to the portal.
     */
    removeListeners(): void;
    /**
     * Returns the active backdrop opacity token.
     * @returns {string} CSS opacity.
     */
    getOpenOpacity(): string;
    /**
     * Resolves the portal stacking layer.
     * @returns {string} CSS z-index.
     */
    getZIndex(): string;
    /**
     * Copies computed token styles from the shadow source to the body portal.
     */
    syncStyles(): void;
    /**
     * Cancels only the animation owned by this controller.
     * @param {Animation|null} animation Animation to cancel.
     */
    cancelAnimation(animation?: Animation | null): void;
    /**
     * Starts the shared backdrop transition.
     * @param {boolean} shouldOpen Target visibility.
     * @param {object} options Timing passed to the Web Animations API.
     * @returns {Animation|null} Started animation.
     */
    animate(shouldOpen: boolean, options: object): Animation | null;
    /**
     * Applies a settled open or closed state.
     * @param {boolean} isOpen Target visibility.
     */
    setOpen(isOpen: boolean): void;
    /**
     * Cancels animation and removes all global state.
     */
    destroy(): void;
}