@deephaven/golden-layout/dist/utils/EventUtils.js

A multi-screen javascript Layout manager

import { useEffect, useRef } from 'react';
/**
 * Listen for an event
 * @param eventEmitter The event emitter to listen to
 * @param event The event to listen for
 * @param handler The handler to call when the event is emitted
 * @returns A function to stop listening for the event
 */
export function listenForEvent(eventEmitter, event, handler) {
  eventEmitter.on(event, handler);
  return () => {
    eventEmitter.off(event, handler);
  };
}
export function makeListenFunction(event) {
  return (eventEmitter, handler) => listenForEvent(eventEmitter, event, handler);
}
export function makeEmitFunction(event) {
  return function (eventEmitter) {
    for (var _len = arguments.length, parameters = new Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
      parameters[_key - 1] = arguments[_key];
    }
    eventEmitter.emit(event, ...parameters);
  };
}
export function makeUseListenerFunction(event) {
  return (eventEmitter, handler) => {
    var eventEmitterRef = useRef(null);
    var handlerRef = useRef(() => false);
    if (eventEmitterRef.current != eventEmitter || handlerRef.current != handler) {
      var _eventEmitterRef$curr;
      (_eventEmitterRef$curr = eventEmitterRef.current) === null || _eventEmitterRef$curr === void 0 || _eventEmitterRef$curr.off(event, handlerRef.current);
      eventEmitter === null || eventEmitter === void 0 || eventEmitter.on(event, handler);
    }
    eventEmitterRef.current = eventEmitter;
    handlerRef.current = handler;

    // Cleanup on unmount
    // Mounting the listener in useEffect causes a race condition with embed-widget
    // where the event is emitted during render before the useEffect runs after render.
    useEffect(() => () => {
      var _eventEmitterRef$curr2;
      return (_eventEmitterRef$curr2 = eventEmitterRef.current) === null || _eventEmitterRef$curr2 === void 0 ? void 0 : _eventEmitterRef$curr2.off(event, handlerRef.current);
    }, []);
  };
}

/**
 * Create listener, emitter, and hook functions for an event
 * @param event Name of the event to create functions for
 * @returns Listener, Emitter, and Hook functions for the event
 */
export function makeEventFunctions(event) {
  return {
    listen: makeListenFunction(event),
    emit: makeEmitFunction(event),
    useListener: makeUseListenerFunction(event)
  };
}
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