react-virtualized/dist/commonjs/WindowScroller/utils/onScroll.js

React components for efficiently rendering large, scrollable lists and tabular data

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.registerScrollListener = registerScrollListener;
exports.unregisterScrollListener = unregisterScrollListener;

var _requestAnimationTimeout = require("../../utils/requestAnimationTimeout");

var _WindowScroller = require("../WindowScroller.js");

var mountedInstances = [];
var originalBodyPointerEvents = null;
var disablePointerEventsTimeoutId = null;

function enablePointerEventsIfDisabled() {
  if (disablePointerEventsTimeoutId) {
    disablePointerEventsTimeoutId = null;

    if (document.body && originalBodyPointerEvents != null) {
      document.body.style.pointerEvents = originalBodyPointerEvents;
    }

    originalBodyPointerEvents = null;
  }
}

function enablePointerEventsAfterDelayCallback() {
  enablePointerEventsIfDisabled();
  mountedInstances.forEach(function (instance) {
    return instance.__resetIsScrolling();
  });
}

function enablePointerEventsAfterDelay() {
  if (disablePointerEventsTimeoutId) {
    (0, _requestAnimationTimeout.cancelAnimationTimeout)(disablePointerEventsTimeoutId);
  }

  var maximumTimeout = 0;
  mountedInstances.forEach(function (instance) {
    maximumTimeout = Math.max(maximumTimeout, instance.props.scrollingResetTimeInterval);
  });
  disablePointerEventsTimeoutId = (0, _requestAnimationTimeout.requestAnimationTimeout)(enablePointerEventsAfterDelayCallback, maximumTimeout);
}

function onScrollWindow(event) {
  if (event.currentTarget === window && originalBodyPointerEvents == null && document.body) {
    originalBodyPointerEvents = document.body.style.pointerEvents;
    document.body.style.pointerEvents = 'none';
  }

  enablePointerEventsAfterDelay();
  mountedInstances.forEach(function (instance) {
    if (instance.props.scrollElement === event.currentTarget) {
      instance.__handleWindowScrollEvent();
    }
  });
}

function registerScrollListener(component, element) {
  if (!mountedInstances.some(function (instance) {
    return instance.props.scrollElement === element;
  })) {
    element.addEventListener('scroll', onScrollWindow);
  }

  mountedInstances.push(component);
}

function unregisterScrollListener(component, element) {
  mountedInstances = mountedInstances.filter(function (instance) {
    return instance !== component;
  });

  if (!mountedInstances.length) {
    element.removeEventListener('scroll', onScrollWindow);

    if (disablePointerEventsTimeoutId) {
      (0, _requestAnimationTimeout.cancelAnimationTimeout)(disablePointerEventsTimeoutId);
      enablePointerEventsIfDisabled();
    }
  }
}