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/*!
 * swiped-events.js - v@version@
 * Pure JavaScript swipe events
 * https://github.com/john-doherty/swiped-events
 * @inspiration https://stackoverflow.com/questions/16348031/disable-scrolling-when-touch-moving-certain-element
 * @author John Doherty <www.johndoherty.info>
 * @license MIT
 */
(function (window, document) {

	'use strict';
  
	// patch CustomEvent to allow constructor creation (IE/Chrome)
	if (typeof window.CustomEvent !== 'function') {
  
	    window.CustomEvent = function (event, params) {
  
		  params = params || { bubbles: false, cancelable: false, detail: undefined };
  
		  var evt = document.createEvent('CustomEvent');
		  evt.initCustomEvent(event, params.bubbles, params.cancelable, params.detail);
		  return evt;
	    };
  
	    window.CustomEvent.prototype = window.Event.prototype;
	}
  
	document.addEventListener('touchstart', handleTouchStart, false);
	document.addEventListener('touchmove', handleTouchMove, false);
	document.addEventListener('touchend', handleTouchEnd, false);
  
	var xDown = null;
	var yDown = null;
	var xDiff = null;
	var yDiff = null;
	var timeDown = null;
	var startEl = null;
  
	/**
	 * Fires swiped event if swipe detected on touchend
	 * @param {object} e - browser event object
	 * @returns {void}
	 */
	function handleTouchEnd(e) {
  
	    // if the user released on a different target, cancel!
	    if (startEl !== e.target) return;
  
	    var swipeThreshold = parseInt(getNearestAttribute(startEl, 'data-swipe-threshold', '20'), 10); // default 20px
	    var swipeTimeout = parseInt(getNearestAttribute(startEl, 'data-swipe-timeout', '500'), 10);    // default 500ms
	    var timeDiff = Date.now() - timeDown;
	    var eventType = '';
	    var changedTouches = e.changedTouches || e.touches || [];
  
	    if (Math.abs(xDiff) > Math.abs(yDiff)) { // most significant
		  if (Math.abs(xDiff) > swipeThreshold && timeDiff < swipeTimeout) {
			if (xDiff > 0) {
			    eventType = 'swiped-left';
			}
			else {
			    eventType = 'swiped-right';
			}
		  }
	    }
	    else if (Math.abs(yDiff) > swipeThreshold && timeDiff < swipeTimeout) {
		  if (yDiff > 0) {
			eventType = 'swiped-up';
		  }
		  else {
			eventType = 'swiped-down';
		  }
	    }
  
	    if (eventType !== '') {
  
		  var eventData = {
			dir: eventType.replace(/swiped-/, ''),
			touchType: (changedTouches[0] || {}).touchType || 'direct',
			xStart: parseInt(xDown, 10),
			xEnd: parseInt((changedTouches[0] || {}).clientX || -1, 10),
			yStart: parseInt(yDown, 10),
			yEnd: parseInt((changedTouches[0] || {}).clientY || -1, 10)
		  };
  
		  // fire `swiped` event event on the element that started the swipe
		  startEl.dispatchEvent(new CustomEvent('swiped', { bubbles: true, cancelable: true, detail: eventData }));
  
		  // fire `swiped-dir` event on the element that started the swipe
		  startEl.dispatchEvent(new CustomEvent(eventType, { bubbles: true, cancelable: true, detail: eventData }));
	    }
  
	    // reset values
	    xDown = null;
	    yDown = null;
	    timeDown = null;
	}
  
	/**
	 * Records current location on touchstart event
	 * @param {object} e - browser event object
	 * @returns {void}
	 */
	function handleTouchStart(e) {
  
	    // if the element has data-swipe-ignore="true" we stop listening for swipe events
	    if (e.target.getAttribute('data-swipe-ignore') === 'true') return;
  
	    startEl = e.target;
  
	    timeDown = Date.now();
	    xDown = e.touches[0].clientX;
	    yDown = e.touches[0].clientY;
	    xDiff = 0;
	    yDiff = 0;
	}
  
	/**
	 * Records location diff in px on touchmove event
	 * @param {object} e - browser event object
	 * @returns {void}
	 */
	function handleTouchMove(e) {
  
	    if (!xDown || !yDown) return;
  
	    var xUp = e.touches[0].clientX;
	    var yUp = e.touches[0].clientY;
  
	    xDiff = xDown - xUp;
	    yDiff = yDown - yUp;
	}
  
	/**
	 * Gets attribute off HTML element or nearest parent
	 * @param {object} el - HTML element to retrieve attribute from
	 * @param {string} attributeName - name of the attribute
	 * @param {any} defaultValue - default value to return if no match found
	 * @returns {any} attribute value or defaultValue
	 */
	function getNearestAttribute(el, attributeName, defaultValue) {
  
	    // walk up the dom tree looking for attributeName
	    while (el && el !== document.documentElement) {
  
		  var attributeValue = el.getAttribute(attributeName);
  
		  if (attributeValue) {
			return attributeValue;
		  }
  
		  el = el.parentNode;
	    }
  
	    return defaultValue;
	}
  
  }(window, document));