src/events.ts

import { refreshActiveHighlight } from "./highlight";
import { emit } from "./emitter";
import { getState, setState } from "./state";

function requireRefresh() {
  const resizeTimeout = getState("resizeTimeout");
  if (resizeTimeout) {
    window.cancelAnimationFrame(resizeTimeout);
  }

  setState("resizeTimeout", window.requestAnimationFrame(refreshActiveHighlight));
}

function onKeyup(e: KeyboardEvent) {
  if (e.key === "Escape") {
    emit("escape");
  }
}

/**
 * Attaches click handler to the elements created by driver.js. It makes
 * sure to give the listener the first chance to handle the event, and
 * prevents all other pointer-events to make sure no external-library
 * ever knows the click happened.
 *
 * @param {Element} element Element to listen for click events
 * @param {(pointer: MouseEvent | PointerEvent) => void} listener Click handler
 * @param {(target: HTMLElement) => boolean} shouldPreventDefault Whether to prevent default action i.e. link clicks etc
 */
export function onDriverClick(
  element: Element,
  listener: (pointer: MouseEvent | PointerEvent) => void,
  shouldPreventDefault?: (target: HTMLElement) => boolean
) {
  const listenerWrapper = (e: MouseEvent | PointerEvent, listener?: (pointer: MouseEvent | PointerEvent) => void) => {
    const target = e.target as HTMLElement;
    if (!element.contains(target)) {
      return;
    }

    if (!shouldPreventDefault || shouldPreventDefault(target)) {
      e.preventDefault();
    }

    e.stopPropagation();
    e.stopImmediatePropagation();

    listener?.(e);
  };

  // We want to be the absolute first one to hear about the event
  const useCapture = true;

  // Events to disable
  document.addEventListener("pointerdown", listenerWrapper, useCapture);
  document.addEventListener("mousedown", listenerWrapper, useCapture);
  document.addEventListener("pointerup", listenerWrapper, useCapture);
  document.addEventListener("mouseup", listenerWrapper, useCapture);

  // Actual click handler
  document.addEventListener(
    "click",
    e => {
      listenerWrapper(e, listener);
    },
    useCapture
  );
}

export function initEvents() {
  window.addEventListener("keyup", onKeyup, false);
  window.addEventListener("resize", requireRefresh);
  window.addEventListener("scroll", requireRefresh);
}

export function destroyEvents() {
  window.removeEventListener("resize", requireRefresh);
  window.removeEventListener("scroll", requireRefresh);
}