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

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

"use strict";
'no babel-plugin-flow-react-proptypes';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.registerScrollListener = registerScrollListener;
exports.unregisterScrollListener = unregisterScrollListener;
var _requestAnimationTimeout = require("../../utils/requestAnimationTimeout");
/*:: import type WindowScroller from '../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 /*: 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 /*: WindowScroller*/, element /*: Element*/) {
  if (!mountedInstances.some(function (instance) {
    return instance.props.scrollElement === element;
  })) {
    element.addEventListener('scroll', onScrollWindow);
  }
  mountedInstances.push(component);
}
function unregisterScrollListener(component /*: WindowScroller*/, element /*: Element*/) {
  mountedInstances = mountedInstances.filter(function (instance) {
    return instance !== component;
  });
  if (!mountedInstances.length) {
    element.removeEventListener('scroll', onScrollWindow);
    if (disablePointerEventsTimeoutId) {
      (0, _requestAnimationTimeout.cancelAnimationTimeout)(disablePointerEventsTimeoutId);
      enablePointerEventsIfDisabled();
    }
  }
}