src/touch.js

//     Zepto.js
//     (c) 2010-2016 Thomas Fuchs
//     Zepto.js may be freely distributed under the MIT license.

;(function($){
  var touch = {},
    touchTimeout, tapTimeout, swipeTimeout, longTapTimeout,
    longTapDelay = 750,
    gesture,
    down, up, move,
    eventMap,
    initialized = false

  function swipeDirection(x1, x2, y1, y2) {
    return Math.abs(x1 - x2) >=
      Math.abs(y1 - y2) ? (x1 - x2 > 0 ? 'Left' : 'Right') : (y1 - y2 > 0 ? 'Up' : 'Down')
  }

  function longTap() {
    longTapTimeout = null
    if (touch.last) {
      touch.el.trigger('longTap')
      touch = {}
    }
  }

  function cancelLongTap() {
    if (longTapTimeout) clearTimeout(longTapTimeout)
    longTapTimeout = null
  }

  function cancelAll() {
    if (touchTimeout) clearTimeout(touchTimeout)
    if (tapTimeout) clearTimeout(tapTimeout)
    if (swipeTimeout) clearTimeout(swipeTimeout)
    if (longTapTimeout) clearTimeout(longTapTimeout)
    touchTimeout = tapTimeout = swipeTimeout = longTapTimeout = null
    touch = {}
  }

  function isPrimaryTouch(event){
    return (event.pointerType == 'touch' ||
      event.pointerType == event.MSPOINTER_TYPE_TOUCH)
      && event.isPrimary
  }

  function isPointerEventType(e, type){
    return (e.type == 'pointer'+type ||
      e.type.toLowerCase() == 'mspointer'+type)
  }

  // helper function for tests, so they check for different APIs
  function unregisterTouchEvents(){
    if (!initialized) return
    $(document).off(eventMap.down, down)
      .off(eventMap.up, up)
      .off(eventMap.move, move)
      .off(eventMap.cancel, cancelAll)
    $(window).off('scroll', cancelAll)
    cancelAll()
    initialized = false
  }

  function setup(__eventMap){
    var now, delta, deltaX = 0, deltaY = 0, firstTouch, _isPointerType

    unregisterTouchEvents()

    eventMap = (__eventMap && ('down' in __eventMap)) ? __eventMap :
      ('ontouchstart' in document ?
      { 'down': 'touchstart', 'up': 'touchend',
        'move': 'touchmove', 'cancel': 'touchcancel' } :
      'onpointerdown' in document ?
      { 'down': 'pointerdown', 'up': 'pointerup',
        'move': 'pointermove', 'cancel': 'pointercancel' } :
       'onmspointerdown' in document ?
      { 'down': 'MSPointerDown', 'up': 'MSPointerUp',
        'move': 'MSPointerMove', 'cancel': 'MSPointerCancel' } : false)

    // No API availables for touch events
    if (!eventMap) return

    if ('MSGesture' in window) {
      gesture = new MSGesture()
      gesture.target = document.body

      $(document)
        .bind('MSGestureEnd', function(e){
          var swipeDirectionFromVelocity =
            e.velocityX > 1 ? 'Right' : e.velocityX < -1 ? 'Left' : e.velocityY > 1 ? 'Down' : e.velocityY < -1 ? 'Up' : null
          if (swipeDirectionFromVelocity) {
            touch.el.trigger('swipe')
            touch.el.trigger('swipe'+ swipeDirectionFromVelocity)
          }
        })
    }

    down = function(e){
      if((_isPointerType = isPointerEventType(e, 'down')) &&
        !isPrimaryTouch(e)) return
      firstTouch = _isPointerType ? e : e.touches[0]
      if (e.touches && e.touches.length === 1 && touch.x2) {
        // Clear out touch movement data if we have it sticking around
        // This can occur if touchcancel doesn't fire due to preventDefault, etc.
        touch.x2 = undefined
        touch.y2 = undefined
      }
      now = Date.now()
      delta = now - (touch.last || now)
      touch.el = $('tagName' in firstTouch.target ?
        firstTouch.target : firstTouch.target.parentNode)
      touchTimeout && clearTimeout(touchTimeout)
      touch.x1 = firstTouch.pageX
      touch.y1 = firstTouch.pageY
      if (delta > 0 && delta <= 250) touch.isDoubleTap = true
      touch.last = now
      longTapTimeout = setTimeout(longTap, longTapDelay)
      // adds the current touch contact for IE gesture recognition
      if (gesture && _isPointerType) gesture.addPointer(e.pointerId)
    }

    move = function(e){
      if((_isPointerType = isPointerEventType(e, 'move')) &&
        !isPrimaryTouch(e)) return
      firstTouch = _isPointerType ? e : e.touches[0]
      cancelLongTap()
      touch.x2 = firstTouch.pageX
      touch.y2 = firstTouch.pageY

      deltaX += Math.abs(touch.x1 - touch.x2)
      deltaY += Math.abs(touch.y1 - touch.y2)
    }

    up = function(e){
      if((_isPointerType = isPointerEventType(e, 'up')) &&
        !isPrimaryTouch(e)) return
      cancelLongTap()

      // swipe
      if ((touch.x2 && Math.abs(touch.x1 - touch.x2) > 30) ||
          (touch.y2 && Math.abs(touch.y1 - touch.y2) > 30))

        swipeTimeout = setTimeout(function() {
          if (touch.el){
            touch.el.trigger('swipe')
            touch.el.trigger('swipe' + (swipeDirection(touch.x1, touch.x2, touch.y1, touch.y2)))
          }
          touch = {}
        }, 0)

      // normal tap
      else if ('last' in touch)
        // don't fire tap when delta position changed by more than 30 pixels,
        // for instance when moving to a point and back to origin
        if (deltaX < 30 && deltaY < 30) {
          // delay by one tick so we can cancel the 'tap' event if 'scroll' fires
          // ('tap' fires before 'scroll')
          tapTimeout = setTimeout(function() {

            // trigger universal 'tap' with the option to cancelTouch()
            // (cancelTouch cancels processing of single vs double taps for faster 'tap' response)
            var event = $.Event('tap')
            event.cancelTouch = cancelAll
            // [by paper] fix -> "TypeError: 'undefined' is not an object (evaluating 'touch.el.trigger'), when double tap
            if (touch.el) touch.el.trigger(event)

            // trigger double tap immediately
            if (touch.isDoubleTap) {
              if (touch.el) touch.el.trigger('doubleTap')
              touch = {}
            }

            // trigger single tap after 250ms of inactivity
            else {
              touchTimeout = setTimeout(function(){
                touchTimeout = null
                if (touch.el) touch.el.trigger('singleTap')
                touch = {}
              }, 250)
            }
          }, 0)
        } else {
          touch = {}
        }
        deltaX = deltaY = 0
    }

    $(document).on(eventMap.up, up)
      .on(eventMap.down, down)
      .on(eventMap.move, move)

    // when the browser window loses focus,
    // for example when a modal dialog is shown,
    // cancel all ongoing events
    $(document).on(eventMap.cancel, cancelAll)

    // scrolling the window indicates intention of the user
    // to scroll, not tap or swipe, so cancel all ongoing events
    $(window).on('scroll', cancelAll)

    initialized = true
  }

  ;['swipe', 'swipeLeft', 'swipeRight', 'swipeUp', 'swipeDown',
    'doubleTap', 'tap', 'singleTap', 'longTap'].forEach(function(eventName){
    $.fn[eventName] = function(callback){ return this.on(eventName, callback) }
  })

  $.touch = { setup: setup }

  $(document).ready(setup)
})(Zepto)