swiper/core/events/onTouchStart.js

Most modern mobile touch slider and framework with hardware accelerated transitions

import { getWindow, getDocument } from 'ssr-window';
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);
    if (!found && !el.getRootNode) {
      return null;
    }
    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;
  data.evCache.push(event);
  const {
    params,
    touches,
    enabled
  } = swiper;
  if (!enabled) return;
  if (!params.simulateTouch && event.pointerType === 'mouse') 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 (!swiper.wrapperEl.contains(targetEl)) return;
  }
  if ('which' in e && e.which === 3) return;
  if ('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 !== '';
  // eslint-disable-next-line
  const eventPath = event.composedPath ? event.composedPath() : event.path;
  if (swipingClassHasValue && e.target && e.target.shadowRoot && eventPath) {
    targetEl = eventPath[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, targetEl) : targetEl.closest(noSwipingSelector))) {
    swiper.allowClick = true;
    return;
  }
  if (params.swipeHandler) {
    if (!targetEl.closest(params.swipeHandler)) return;
  }
  touches.currentX = e.pageX;
  touches.currentY = 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;
  let preventDefault = true;
  if (targetEl.matches(data.focusableElements)) {
    preventDefault = false;
    if (targetEl.nodeName === 'SELECT') {
      data.isTouched = false;
    }
  }
  if (document.activeElement && document.activeElement.matches(data.focusableElements) && document.activeElement !== targetEl) {
    document.activeElement.blur();
  }
  const shouldPreventDefault = preventDefault && swiper.allowTouchMove && params.touchStartPreventDefault;
  if ((params.touchStartForcePreventDefault || shouldPreventDefault) && !targetEl.isContentEditable) {
    e.preventDefault();
  }
  if (swiper.params.freeMode && swiper.params.freeMode.enabled && swiper.freeMode && swiper.animating && !params.cssMode) {
    swiper.freeMode.onTouchStart();
  }
  swiper.emit('touchStart', e);
}