type callback = () => void;
/**
 * Listen keydown/keyup event on document for a specific keyboard key.
 */
export declare class ListenKey {
    private readonly listenedKey;
    private readonly eventKeys;
    private keyDown;
    private keyDownCallback?;
    private keyUpCallback?;
    /**
     * @param listenedKey the key to listen.
     */
    constructor(listenedKey: string);
    /**
     * Destroy listeners. The instance is then useless.
     */
    destroy(): void;
    /**
     * Is the key currently pressed.
     */
    isKeyDown(): boolean;
    /**
     * Register a callback that will be called each time the key is pressed.
     * @param callback
     */
    setOnKeyDown(callback: callback): void;
    /**
     * Register a callback that will be called each time the key is released.
     * @param callback
     */
    setOnKeyUp(callback: callback): void;
    /**
     * Check if the key is pressed.
     * @private
     */
    private handleKeyDown;
    /**
     * Check if the key is released.
     * @private
     */
    private handleKeyUp;
}
export {};