interface StyleObserverChangeObject {
    value: string;
    previousValue: string;
    changed: boolean;
    element: HTMLElement;
}
type StyleObserverChangesWithObjects = {
    [key: string]: StyleObserverChangeObject;
};
type StyleObserverChangesWithValues = {
    [key: string]: StyleObserverChangeValue;
};
type StyleObserverChangeValue = string;
export type StyleObserverChanges = StyleObserverChangesWithObjects | StyleObserverChangesWithValues;
export type StyleObserverCallback = (values: Readonly<StyleObserverChanges>) => void;
type CachedValues = {
    [key: string]: string;
};
export declare enum ReturnFormat {
    VALUE_ONLY = "value_only",
    OBJECT = "object"
}
export declare enum NotificationMode {
    CHANGED_ONLY = "changed_only",
    ALL = "all"
}
export interface StyleObserverConfig {
    properties: string[];
    notificationMode?: NotificationMode;
    returnFormat?: ReturnFormat;
}
export declare class StyleObserver {
    _observedElements: Set<HTMLElement>;
    _cachedValues: WeakMap<HTMLElement, CachedValues>;
    constructor(callback: StyleObserverCallback, config?: StyleObserverConfig);
    observe(targetElement: HTMLElement): void;
    unobserve(targetElement?: HTMLElement): void;
    private _observedVariables;
    private _callback;
    private _eventHandler;
    private _notificationMode;
    private _returnFormat;
    private _setTargetElementStyles;
    private _unsetTargetElementStyles;
    private _processComputedStyle;
    private _getFormatter;
    private _handleUpdate;
}
export default StyleObserver;