/**
 * Possible CanKing event channels for an extension to listen to.
 */
export type extensionEventChannels = 'devices-changed' | 'new-log-messages' | 'online-status-changed' | 'periodic-trans-started' | 'periodic-trans-stopped' | 'new-measurement-data' | 'new-measurement-status' | 'user-settings-changed' | 'meas-setup-changed' | 'workspace-panes-changed';
/**
 * Starts a subscription to an event raised by CanKing.
 *
 * @typeParam T - Type of the data that will be sent by the event.
 * @param key - A unique key for this subscription, this key should be used when calling removeEventListener to unsubcribe
 *              from the event. The uuid package can be used for generating unique keys.
 * @param event - The event channel to subscibe to.
 * @param callback - A callback that will be called when new data arrives on the channel.
 * @param options - Optional options including following options:
 *                  numberOfHistoryFrames - used when adding a 'new-measurement-data' event listener to control number of frames to read from history at initialization.
 * @returns A promise that will resolve with start values for the event.
 * @internal
 */
export declare function addEventListener<T>(key: string, event: extensionEventChannels, callback: (data: T) => void, options?: {
    numberOfHistoryFrames?: number;
}): Promise<T>;
/**
 * Unsubscribes from an event.
 *
 * @param key - The key that was used when addEventListener was called.
 * @param event - The event channel to unsubscribe from.
 * @internal
 */
export declare const removeEventListener: (key: string, event: extensionEventChannels) => Promise<void>;