swiper/core/events/onTouchStart.js

import { getWindow, getDocument } from 'ssr-window';
import $ from '../../shared/dom.js';
import { now } from '../../shared/utils.js'; // Modified from https://stackoverflow.com/questions/54520554/custom-element-getrootnode-closest-function-crossing-multiple-parent-shadowd

function closestElement(selector, base = this) {
  function __closestFrom(el) {
    if (!el || el === getDocument() || el === getWindow()) return null;
    if (el.assignedSlot) el = el.assignedSlot;
    const found = el.closest(selector);
    return found || __closestFrom(el.getRootNode().host);
  }

  return __closestFrom(base);
}

export default function onTouchStart(event) {
  const swiper = this;
  const document = getDocument();
  const window = getWindow();
  const data = swiper.touchEventsData;
  const {
    params,
    touches,
    enabled
  } = swiper;
  if (!enabled) return;

  if (swiper.animating && params.preventInteractionOnTransition) {
    return;
  }

  if (!swiper.animating && params.cssMode && params.loop) {
    swiper.loopFix();
  }

  let e = event;
  if (e.originalEvent) e = e.originalEvent;
  let $targetEl = $(e.target);

  if (params.touchEventsTarget === 'wrapper') {
    if (!$targetEl.closest(swiper.wrapperEl).length) return;
  }

  data.isTouchEvent = e.type === 'touchstart';
  if (!data.isTouchEvent && 'which' in e && e.which === 3) return;
  if (!data.isTouchEvent && 'button' in e && e.button > 0) return;
  if (data.isTouched && data.isMoved) return; // change target el for shadow root component

  const swipingClassHasValue = !!params.noSwipingClass && params.noSwipingClass !== '';

  if (swipingClassHasValue && e.target && e.target.shadowRoot && event.path && event.path[0]) {
    $targetEl = $(event.path[0]);
  }

  const noSwipingSelector = params.noSwipingSelector ? params.noSwipingSelector : `.${params.noSwipingClass}`;
  const isTargetShadow = !!(e.target && e.target.shadowRoot); // use closestElement for shadow root element to get the actual closest for nested shadow root element

  if (params.noSwiping && (isTargetShadow ? closestElement(noSwipingSelector, e.target) : $targetEl.closest(noSwipingSelector)[0])) {
    swiper.allowClick = true;
    return;
  }

  if (params.swipeHandler) {
    if (!$targetEl.closest(params.swipeHandler)[0]) return;
  }

  touches.currentX = e.type === 'touchstart' ? e.targetTouches[0].pageX : e.pageX;
  touches.currentY = e.type === 'touchstart' ? e.targetTouches[0].pageY : e.pageY;
  const startX = touches.currentX;
  const startY = touches.currentY; // Do NOT start if iOS edge swipe is detected. Otherwise iOS app cannot swipe-to-go-back anymore

  const edgeSwipeDetection = params.edgeSwipeDetection || params.iOSEdgeSwipeDetection;
  const edgeSwipeThreshold = params.edgeSwipeThreshold || params.iOSEdgeSwipeThreshold;

  if (edgeSwipeDetection && (startX <= edgeSwipeThreshold || startX >= window.innerWidth - edgeSwipeThreshold)) {
    if (edgeSwipeDetection === 'prevent') {
      event.preventDefault();
    } else {
      return;
    }
  }

  Object.assign(data, {
    isTouched: true,
    isMoved: false,
    allowTouchCallbacks: true,
    isScrolling: undefined,
    startMoving: undefined
  });
  touches.startX = startX;
  touches.startY = startY;
  data.touchStartTime = now();
  swiper.allowClick = true;
  swiper.updateSize();
  swiper.swipeDirection = undefined;
  if (params.threshold > 0) data.allowThresholdMove = false;

  if (e.type !== 'touchstart') {
    let preventDefault = true;
    if ($targetEl.is(data.focusableElements)) preventDefault = false;

    if (document.activeElement && $(document.activeElement).is(data.focusableElements) && document.activeElement !== $targetEl[0]) {
      document.activeElement.blur();
    }

    const shouldPreventDefault = preventDefault && swiper.allowTouchMove && params.touchStartPreventDefault;

    if ((params.touchStartForcePreventDefault || shouldPreventDefault) && !$targetEl[0].isContentEditable) {
      e.preventDefault();
    }
  }

  swiper.emit('touchStart', e);
}