swiper/src/components/core/events/onTouchStart.js

Most modern mobile touch slider and framework with hardware accelerated transitions

import { window, document } from 'ssr-window';
import $ from '../../../utils/dom';
import Utils from '../../../utils/utils';

export default function (event) {
  const swiper = this;
  const data = swiper.touchEventsData;
  const { params, touches } = swiper;

  if (swiper.animating && params.preventInteractionOnTransition) {
    return;
  }
  let e = event;
  if (e.originalEvent) e = e.originalEvent;
  const $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;
  if (params.noSwiping && $targetEl.closest(params.noSwipingSelector ? params.noSwipingSelector : `.${params.noSwipingClass}`)[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.screen.width - edgeSwipeThreshold))
  ) {
    return;
  }

  Utils.extend(data, {
    isTouched: true,
    isMoved: false,
    allowTouchCallbacks: true,
    isScrolling: undefined,
    startMoving: undefined,
  });

  touches.startX = startX;
  touches.startY = startY;
  data.touchStartTime = Utils.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.formElements)) preventDefault = false;
    if (
      document.activeElement
      && $(document.activeElement).is(data.formElements)
      && document.activeElement !== $targetEl[0]
    ) {
      document.activeElement.blur();
    }

    const shouldPreventDefault = preventDefault && swiper.allowTouchMove && params.touchStartPreventDefault;
    if (params.touchStartForcePreventDefault || shouldPreventDefault) {
      e.preventDefault();
    }
  }
  swiper.emit('touchStart', e);
}