gestures.js

/**
  * Simple gesture controllers with some common gestures that emit
  * gesture events.
  *
  * Ported from github.com/EightMedia/hammer.js Gestures - thanks!
  */
(function(ionic) {

  /**
   * ionic.Gestures
   * use this to create instances
   * @param   {HTMLElement}   element
   * @param   {Object}        options
   * @returns {ionic.Gestures.Instance}
   * @constructor
   */
  ionic.Gesture = function(element, options) {
    return new ionic.Gestures.Instance(element, options || {});
  };

  ionic.Gestures = {};

  // default settings
  ionic.Gestures.defaults = {
    // add css to the element to prevent the browser from doing
    // its native behavior. this doesnt prevent the scrolling,
    // but cancels the contextmenu, tap highlighting etc
    // set to false to disable this
    stop_browser_behavior: 'disable-user-behavior'
  };

  // detect touchevents
  ionic.Gestures.HAS_POINTEREVENTS = window.navigator.pointerEnabled || window.navigator.msPointerEnabled;
  ionic.Gestures.HAS_TOUCHEVENTS = ('ontouchstart' in window);

  // dont use mouseevents on mobile devices
  ionic.Gestures.MOBILE_REGEX = /mobile|tablet|ip(ad|hone|od)|android|silk/i;
  ionic.Gestures.NO_MOUSEEVENTS = ionic.Gestures.HAS_TOUCHEVENTS && window.navigator.userAgent.match(ionic.Gestures.MOBILE_REGEX);

  // eventtypes per touchevent (start, move, end)
  // are filled by ionic.Gestures.event.determineEventTypes on setup
  ionic.Gestures.EVENT_TYPES = {};

  // direction defines
  ionic.Gestures.DIRECTION_DOWN = 'down';
  ionic.Gestures.DIRECTION_LEFT = 'left';
  ionic.Gestures.DIRECTION_UP = 'up';
  ionic.Gestures.DIRECTION_RIGHT = 'right';

  // pointer type
  ionic.Gestures.POINTER_MOUSE = 'mouse';
  ionic.Gestures.POINTER_TOUCH = 'touch';
  ionic.Gestures.POINTER_PEN = 'pen';

  // touch event defines
  ionic.Gestures.EVENT_START = 'start';
  ionic.Gestures.EVENT_MOVE = 'move';
  ionic.Gestures.EVENT_END = 'end';

  // hammer document where the base events are added at
  ionic.Gestures.DOCUMENT = window.document;

  // plugins namespace
  ionic.Gestures.plugins = {};

  // if the window events are set...
  ionic.Gestures.READY = false;

  /**
   * setup events to detect gestures on the document
   */
  function setup() {
    if(ionic.Gestures.READY) {
      return;
    }

    // find what eventtypes we add listeners to
    ionic.Gestures.event.determineEventTypes();

    // Register all gestures inside ionic.Gestures.gestures
    for(var name in ionic.Gestures.gestures) {
      if(ionic.Gestures.gestures.hasOwnProperty(name)) {
        ionic.Gestures.detection.register(ionic.Gestures.gestures[name]);
      }
    }

    // Add touch events on the document
    ionic.Gestures.event.onTouch(ionic.Gestures.DOCUMENT, ionic.Gestures.EVENT_MOVE, ionic.Gestures.detection.detect);
    ionic.Gestures.event.onTouch(ionic.Gestures.DOCUMENT, ionic.Gestures.EVENT_END, ionic.Gestures.detection.detect);

    // ionic.Gestures is ready...!
    ionic.Gestures.READY = true;
  }

  /**
   * create new hammer instance
   * all methods should return the instance itself, so it is chainable.
   * @param   {HTMLElement}       element
   * @param   {Object}            [options={}]
   * @returns {ionic.Gestures.Instance}
   * @name Gesture.Instance
   * @constructor
   */
  ionic.Gestures.Instance = function(element, options) {
    var self = this;

    // A null element was passed into the instance, which means
    // whatever lookup was done to find this element failed to find it
    // so we can't listen for events on it.
    if(element === null) {
      console.error('Null element passed to gesture (element does not exist). Not listening for gesture');
      return;
    }

    // setup ionic.GesturesJS window events and register all gestures
    // this also sets up the default options
    setup();

    this.element = element;

    // start/stop detection option
    this.enabled = true;

    // merge options
    this.options = ionic.Gestures.utils.extend(
        ionic.Gestures.utils.extend({}, ionic.Gestures.defaults),
        options || {});

    // add some css to the element to prevent the browser from doing its native behavoir
    if(this.options.stop_browser_behavior) {
      ionic.Gestures.utils.stopDefaultBrowserBehavior(this.element, this.options.stop_browser_behavior);
    }

    // start detection on touchstart
    ionic.Gestures.event.onTouch(element, ionic.Gestures.EVENT_START, function(ev) {
      if(self.enabled) {
        ionic.Gestures.detection.startDetect(self, ev);
      }
    });

    // return instance
    return this;
  };


  ionic.Gestures.Instance.prototype = {
    /**
     * bind events to the instance
     * @param   {String}      gesture
     * @param   {Function}    handler
     * @returns {ionic.Gestures.Instance}
     */
    on: function onEvent(gesture, handler){
      var gestures = gesture.split(' ');
      for(var t=0; t<gestures.length; t++) {
        this.element.addEventListener(gestures[t], handler, false);
      }
      return this;
    },


    /**
     * unbind events to the instance
     * @param   {String}      gesture
     * @param   {Function}    handler
     * @returns {ionic.Gestures.Instance}
     */
    off: function offEvent(gesture, handler){
      var gestures = gesture.split(' ');
      for(var t=0; t<gestures.length; t++) {
        this.element.removeEventListener(gestures[t], handler, false);
      }
      return this;
    },


    /**
     * trigger gesture event
     * @param   {String}      gesture
     * @param   {Object}      eventData
     * @returns {ionic.Gestures.Instance}
     */
    trigger: function triggerEvent(gesture, eventData){
      // create DOM event
      var event = ionic.Gestures.DOCUMENT.createEvent('Event');
      event.initEvent(gesture, true, true);
      event.gesture = eventData;

      // trigger on the target if it is in the instance element,
      // this is for event delegation tricks
      var element = this.element;
      if(ionic.Gestures.utils.hasParent(eventData.target, element)) {
        element = eventData.target;
      }

      element.dispatchEvent(event);
      return this;
    },


    /**
     * enable of disable hammer.js detection
     * @param   {Boolean}   state
     * @returns {ionic.Gestures.Instance}
     */
    enable: function enable(state) {
      this.enabled = state;
      return this;
    }
  };

  /**
   * this holds the last move event,
   * used to fix empty touchend issue
   * see the onTouch event for an explanation
   * type {Object}
   */
  var last_move_event = null;


  /**
   * when the mouse is hold down, this is true
   * type {Boolean}
   */
  var enable_detect = false;


  /**
   * when touch events have been fired, this is true
   * type {Boolean}
   */
  var touch_triggered = false;


  ionic.Gestures.event = {
    /**
     * simple addEventListener
     * @param   {HTMLElement}   element
     * @param   {String}        type
     * @param   {Function}      handler
     */
    bindDom: function(element, type, handler) {
      var types = type.split(' ');
      for(var t=0; t<types.length; t++) {
        element.addEventListener(types[t], handler, false);
      }
    },


    /**
     * touch events with mouse fallback
     * @param   {HTMLElement}   element
     * @param   {String}        eventType        like ionic.Gestures.EVENT_MOVE
     * @param   {Function}      handler
     */
    onTouch: function onTouch(element, eventType, handler) {
      var self = this;

      this.bindDom(element, ionic.Gestures.EVENT_TYPES[eventType], function bindDomOnTouch(ev) {
        var sourceEventType = ev.type.toLowerCase();

        // onmouseup, but when touchend has been fired we do nothing.
        // this is for touchdevices which also fire a mouseup on touchend
        if(sourceEventType.match(/mouse/) && touch_triggered) {
          return;
        }

        // mousebutton must be down or a touch event
        else if( sourceEventType.match(/touch/) ||   // touch events are always on screen
          sourceEventType.match(/pointerdown/) || // pointerevents touch
          (sourceEventType.match(/mouse/) && ev.which === 1)   // mouse is pressed
          ){
            enable_detect = true;
          }

        // mouse isn't pressed
        else if(sourceEventType.match(/mouse/) && ev.which !== 1) {
          enable_detect = false;
        }


        // we are in a touch event, set the touch triggered bool to true,
        // this for the conflicts that may occur on ios and android
        if(sourceEventType.match(/touch|pointer/)) {
          touch_triggered = true;
        }

        // count the total touches on the screen
        var count_touches = 0;

        // when touch has been triggered in this detection session
        // and we are now handling a mouse event, we stop that to prevent conflicts
        if(enable_detect) {
          // update pointerevent
          if(ionic.Gestures.HAS_POINTEREVENTS && eventType != ionic.Gestures.EVENT_END) {
            count_touches = ionic.Gestures.PointerEvent.updatePointer(eventType, ev);
          }
          // touch
          else if(sourceEventType.match(/touch/)) {
            count_touches = ev.touches.length;
          }
          // mouse
          else if(!touch_triggered) {
            count_touches = sourceEventType.match(/up/) ? 0 : 1;
          }

          // if we are in a end event, but when we remove one touch and
          // we still have enough, set eventType to move
          if(count_touches > 0 && eventType == ionic.Gestures.EVENT_END) {
            eventType = ionic.Gestures.EVENT_MOVE;
          }
          // no touches, force the end event
          else if(!count_touches) {
            eventType = ionic.Gestures.EVENT_END;
          }

          // store the last move event
          if(count_touches || last_move_event === null) {
            last_move_event = ev;
          }

          // trigger the handler
          handler.call(ionic.Gestures.detection, self.collectEventData(element, eventType, self.getTouchList(last_move_event, eventType), ev));

          // remove pointerevent from list
          if(ionic.Gestures.HAS_POINTEREVENTS && eventType == ionic.Gestures.EVENT_END) {
            count_touches = ionic.Gestures.PointerEvent.updatePointer(eventType, ev);
          }
        }

        //debug(sourceEventType +" "+ eventType);

        // on the end we reset everything
        if(!count_touches) {
          last_move_event = null;
          enable_detect = false;
          touch_triggered = false;
          ionic.Gestures.PointerEvent.reset();
        }
      });
    },


    /**
     * we have different events for each device/browser
     * determine what we need and set them in the ionic.Gestures.EVENT_TYPES constant
     */
    determineEventTypes: function determineEventTypes() {
      // determine the eventtype we want to set
      var types;

      // pointerEvents magic
      if(ionic.Gestures.HAS_POINTEREVENTS) {
        types = ionic.Gestures.PointerEvent.getEvents();
      }
      // on Android, iOS, blackberry, windows mobile we dont want any mouseevents
      else if(ionic.Gestures.NO_MOUSEEVENTS) {
        types = [
          'touchstart',
          'touchmove',
          'touchend touchcancel'];
      }
      // for non pointer events browsers and mixed browsers,
      // like chrome on windows8 touch laptop
      else {
        types = [
          'touchstart mousedown',
          'touchmove mousemove',
          'touchend touchcancel mouseup'];
      }

      ionic.Gestures.EVENT_TYPES[ionic.Gestures.EVENT_START]  = types[0];
      ionic.Gestures.EVENT_TYPES[ionic.Gestures.EVENT_MOVE]   = types[1];
      ionic.Gestures.EVENT_TYPES[ionic.Gestures.EVENT_END]    = types[2];
    },


    /**
     * create touchlist depending on the event
     * @param   {Object}    ev
     * @param   {String}    eventType   used by the fakemultitouch plugin
     */
    getTouchList: function getTouchList(ev/*, eventType*/) {
      // get the fake pointerEvent touchlist
      if(ionic.Gestures.HAS_POINTEREVENTS) {
        return ionic.Gestures.PointerEvent.getTouchList();
      }
      // get the touchlist
      else if(ev.touches) {
        return ev.touches;
      }
      // make fake touchlist from mouse position
      else {
        ev.identifier = 1;
        return [ev];
      }
    },


    /**
     * collect event data for ionic.Gestures js
     * @param   {HTMLElement}   element
     * @param   {String}        eventType        like ionic.Gestures.EVENT_MOVE
     * @param   {Object}        eventData
     */
    collectEventData: function collectEventData(element, eventType, touches, ev) {

      // find out pointerType
      var pointerType = ionic.Gestures.POINTER_TOUCH;
      if(ev.type.match(/mouse/) || ionic.Gestures.PointerEvent.matchType(ionic.Gestures.POINTER_MOUSE, ev)) {
        pointerType = ionic.Gestures.POINTER_MOUSE;
      }

      return {
        center      : ionic.Gestures.utils.getCenter(touches),
                    timeStamp   : new Date().getTime(),
                    target      : ev.target,
                    touches     : touches,
                    eventType   : eventType,
                    pointerType : pointerType,
                    srcEvent    : ev,

                    /**
                     * prevent the browser default actions
                     * mostly used to disable scrolling of the browser
                     */
                    preventDefault: function() {
                      if(this.srcEvent.preventManipulation) {
                        this.srcEvent.preventManipulation();
                      }

                      if(this.srcEvent.preventDefault) {
                        //this.srcEvent.preventDefault();
                      }
                    },

                    /**
                     * stop bubbling the event up to its parents
                     */
                    stopPropagation: function() {
                      this.srcEvent.stopPropagation();
                    },

                    /**
                     * immediately stop gesture detection
                     * might be useful after a swipe was detected
                     * @return {*}
                     */
                    stopDetect: function() {
                      return ionic.Gestures.detection.stopDetect();
                    }
      };
    }
  };

  ionic.Gestures.PointerEvent = {
    /**
     * holds all pointers
     * type {Object}
     */
    pointers: {},

    /**
     * get a list of pointers
     * @returns {Array}     touchlist
     */
    getTouchList: function() {
      var self = this;
      var touchlist = [];

      // we can use forEach since pointerEvents only is in IE10
      Object.keys(self.pointers).sort().forEach(function(id) {
        touchlist.push(self.pointers[id]);
      });
      return touchlist;
    },

    /**
     * update the position of a pointer
     * @param   {String}   type             ionic.Gestures.EVENT_END
     * @param   {Object}   pointerEvent
     */
    updatePointer: function(type, pointerEvent) {
      if(type == ionic.Gestures.EVENT_END) {
        this.pointers = {};
      }
      else {
        pointerEvent.identifier = pointerEvent.pointerId;
        this.pointers[pointerEvent.pointerId] = pointerEvent;
      }

      return Object.keys(this.pointers).length;
    },

    /**
     * check if ev matches pointertype
     * @param   {String}        pointerType     ionic.Gestures.POINTER_MOUSE
     * @param   {PointerEvent}  ev
     */
    matchType: function(pointerType, ev) {
      if(!ev.pointerType) {
        return false;
      }

      var types = {};
      types[ionic.Gestures.POINTER_MOUSE] = (ev.pointerType == ev.MSPOINTER_TYPE_MOUSE || ev.pointerType == ionic.Gestures.POINTER_MOUSE);
      types[ionic.Gestures.POINTER_TOUCH] = (ev.pointerType == ev.MSPOINTER_TYPE_TOUCH || ev.pointerType == ionic.Gestures.POINTER_TOUCH);
      types[ionic.Gestures.POINTER_PEN] = (ev.pointerType == ev.MSPOINTER_TYPE_PEN || ev.pointerType == ionic.Gestures.POINTER_PEN);
      return types[pointerType];
    },


    /**
     * get events
     */
    getEvents: function() {
      return [
        'pointerdown MSPointerDown',
      'pointermove MSPointerMove',
      'pointerup pointercancel MSPointerUp MSPointerCancel'
        ];
    },

    /**
     * reset the list
     */
    reset: function() {
      this.pointers = {};
    }
  };


  ionic.Gestures.utils = {
    /**
     * extend method,
     * also used for cloning when dest is an empty object
     * @param   {Object}    dest
     * @param   {Object}    src
     * @param	{Boolean}	merge		do a merge
     * @returns {Object}    dest
     */
    extend: function extend(dest, src, merge) {
      for (var key in src) {
        if(dest[key] !== undefined && merge) {
          continue;
        }
        dest[key] = src[key];
      }
      return dest;
    },


    /**
     * find if a node is in the given parent
     * used for event delegation tricks
     * @param   {HTMLElement}   node
     * @param   {HTMLElement}   parent
     * @returns {boolean}       has_parent
     */
    hasParent: function(node, parent) {
      while(node){
        if(node == parent) {
          return true;
        }
        node = node.parentNode;
      }
      return false;
    },


    /**
     * get the center of all the touches
     * @param   {Array}     touches
     * @returns {Object}    center
     */
    getCenter: function getCenter(touches) {
      var valuesX = [], valuesY = [];

      for(var t= 0,len=touches.length; t<len; t++) {
        valuesX.push(touches[t].pageX);
        valuesY.push(touches[t].pageY);
      }

      return {
        pageX: ((Math.min.apply(Math, valuesX) + Math.max.apply(Math, valuesX)) / 2),
          pageY: ((Math.min.apply(Math, valuesY) + Math.max.apply(Math, valuesY)) / 2)
      };
    },


    /**
     * calculate the velocity between two points
     * @param   {Number}    delta_time
     * @param   {Number}    delta_x
     * @param   {Number}    delta_y
     * @returns {Object}    velocity
     */
    getVelocity: function getVelocity(delta_time, delta_x, delta_y) {
      return {
        x: Math.abs(delta_x / delta_time) || 0,
        y: Math.abs(delta_y / delta_time) || 0
      };
    },


    /**
     * calculate the angle between two coordinates
     * @param   {Touch}     touch1
     * @param   {Touch}     touch2
     * @returns {Number}    angle
     */
    getAngle: function getAngle(touch1, touch2) {
      var y = touch2.pageY - touch1.pageY,
      x = touch2.pageX - touch1.pageX;
      return Math.atan2(y, x) * 180 / Math.PI;
    },


    /**
     * angle to direction define
     * @param   {Touch}     touch1
     * @param   {Touch}     touch2
     * @returns {String}    direction constant, like ionic.Gestures.DIRECTION_LEFT
     */
    getDirection: function getDirection(touch1, touch2) {
      var x = Math.abs(touch1.pageX - touch2.pageX),
      y = Math.abs(touch1.pageY - touch2.pageY);

      if(x >= y) {
        return touch1.pageX - touch2.pageX > 0 ? ionic.Gestures.DIRECTION_LEFT : ionic.Gestures.DIRECTION_RIGHT;
      }
      else {
        return touch1.pageY - touch2.pageY > 0 ? ionic.Gestures.DIRECTION_UP : ionic.Gestures.DIRECTION_DOWN;
      }
    },


    /**
     * calculate the distance between two touches
     * @param   {Touch}     touch1
     * @param   {Touch}     touch2
     * @returns {Number}    distance
     */
    getDistance: function getDistance(touch1, touch2) {
      var x = touch2.pageX - touch1.pageX,
      y = touch2.pageY - touch1.pageY;
      return Math.sqrt((x*x) + (y*y));
    },


    /**
     * calculate the scale factor between two touchLists (fingers)
     * no scale is 1, and goes down to 0 when pinched together, and bigger when pinched out
     * @param   {Array}     start
     * @param   {Array}     end
     * @returns {Number}    scale
     */
    getScale: function getScale(start, end) {
      // need two fingers...
      if(start.length >= 2 && end.length >= 2) {
        return this.getDistance(end[0], end[1]) /
          this.getDistance(start[0], start[1]);
      }
      return 1;
    },


    /**
     * calculate the rotation degrees between two touchLists (fingers)
     * @param   {Array}     start
     * @param   {Array}     end
     * @returns {Number}    rotation
     */
    getRotation: function getRotation(start, end) {
      // need two fingers
      if(start.length >= 2 && end.length >= 2) {
        return this.getAngle(end[1], end[0]) -
          this.getAngle(start[1], start[0]);
      }
      return 0;
    },


    /**
     * boolean if the direction is vertical
     * @param    {String}    direction
     * @returns  {Boolean}   is_vertical
     */
    isVertical: function isVertical(direction) {
      return (direction == ionic.Gestures.DIRECTION_UP || direction == ionic.Gestures.DIRECTION_DOWN);
    },


    /**
     * stop browser default behavior with css class
     * @param   {HtmlElement}   element
     * @param   {Object}        css_class
     */
    stopDefaultBrowserBehavior: function stopDefaultBrowserBehavior(element, css_class) {
      // changed from making many style changes to just adding a preset classname
      // less DOM manipulations, less code, and easier to control in the CSS side of things
      // hammer.js doesn't come with CSS, but ionic does, which is why we prefer this method
      if(element && element.classList) {
        element.classList.add(css_class);
        element.onselectstart = function() {
          return false;
        };
      }
    }
  };


  ionic.Gestures.detection = {
    // contains all registred ionic.Gestures.gestures in the correct order
    gestures: [],

    // data of the current ionic.Gestures.gesture detection session
    current: null,

    // the previous ionic.Gestures.gesture session data
    // is a full clone of the previous gesture.current object
    previous: null,

    // when this becomes true, no gestures are fired
    stopped: false,


    /**
     * start ionic.Gestures.gesture detection
     * @param   {ionic.Gestures.Instance}   inst
     * @param   {Object}            eventData
     */
    startDetect: function startDetect(inst, eventData) {
      // already busy with a ionic.Gestures.gesture detection on an element
      if(this.current) {
        return;
      }

      this.stopped = false;

      this.current = {
        inst        : inst, // reference to ionic.GesturesInstance we're working for
        startEvent  : ionic.Gestures.utils.extend({}, eventData), // start eventData for distances, timing etc
        lastEvent   : false, // last eventData
        name        : '' // current gesture we're in/detected, can be 'tap', 'hold' etc
      };

      this.detect(eventData);
    },


    /**
     * ionic.Gestures.gesture detection
     * @param   {Object}    eventData
     */
    detect: function detect(eventData) {
      if(!this.current || this.stopped) {
        return;
      }

      // extend event data with calculations about scale, distance etc
      eventData = this.extendEventData(eventData);

      // instance options
      var inst_options = this.current.inst.options;

      // call ionic.Gestures.gesture handlers
      for(var g=0,len=this.gestures.length; g<len; g++) {
        var gesture = this.gestures[g];

        // only when the instance options have enabled this gesture
        if(!this.stopped && inst_options[gesture.name] !== false) {
          // if a handler returns false, we stop with the detection
          if(gesture.handler.call(gesture, eventData, this.current.inst) === false) {
            this.stopDetect();
            break;
          }
        }
      }

      // store as previous event event
      if(this.current) {
        this.current.lastEvent = eventData;
      }

      // endevent, but not the last touch, so dont stop
      if(eventData.eventType == ionic.Gestures.EVENT_END && !eventData.touches.length-1) {
        this.stopDetect();
      }

      return eventData;
    },


    /**
     * clear the ionic.Gestures.gesture vars
     * this is called on endDetect, but can also be used when a final ionic.Gestures.gesture has been detected
     * to stop other ionic.Gestures.gestures from being fired
     */
    stopDetect: function stopDetect() {
      // clone current data to the store as the previous gesture
      // used for the double tap gesture, since this is an other gesture detect session
      this.previous = ionic.Gestures.utils.extend({}, this.current);

      // reset the current
      this.current = null;

      // stopped!
      this.stopped = true;
    },


    /**
     * extend eventData for ionic.Gestures.gestures
     * @param   {Object}   ev
     * @returns {Object}   ev
     */
    extendEventData: function extendEventData(ev) {
      var startEv = this.current.startEvent;

      // if the touches change, set the new touches over the startEvent touches
      // this because touchevents don't have all the touches on touchstart, or the
      // user must place his fingers at the EXACT same time on the screen, which is not realistic
      // but, sometimes it happens that both fingers are touching at the EXACT same time
      if(startEv && (ev.touches.length != startEv.touches.length || ev.touches === startEv.touches)) {
        // extend 1 level deep to get the touchlist with the touch objects
        startEv.touches = [];
        for(var i=0,len=ev.touches.length; i<len; i++) {
          startEv.touches.push(ionic.Gestures.utils.extend({}, ev.touches[i]));
        }
      }

      var delta_time = ev.timeStamp - startEv.timeStamp,
          delta_x = ev.center.pageX - startEv.center.pageX,
          delta_y = ev.center.pageY - startEv.center.pageY,
          velocity = ionic.Gestures.utils.getVelocity(delta_time, delta_x, delta_y);

      ionic.Gestures.utils.extend(ev, {
        deltaTime   : delta_time,

        deltaX      : delta_x,
        deltaY      : delta_y,

        velocityX   : velocity.x,
        velocityY   : velocity.y,

        distance    : ionic.Gestures.utils.getDistance(startEv.center, ev.center),
        angle       : ionic.Gestures.utils.getAngle(startEv.center, ev.center),
        direction   : ionic.Gestures.utils.getDirection(startEv.center, ev.center),

        scale       : ionic.Gestures.utils.getScale(startEv.touches, ev.touches),
        rotation    : ionic.Gestures.utils.getRotation(startEv.touches, ev.touches),

        startEvent  : startEv
      });

      return ev;
    },


    /**
     * register new gesture
     * @param   {Object}    gesture object, see gestures.js for documentation
     * @returns {Array}     gestures
     */
    register: function register(gesture) {
      // add an enable gesture options if there is no given
      var options = gesture.defaults || {};
      if(options[gesture.name] === undefined) {
        options[gesture.name] = true;
      }

      // extend ionic.Gestures default options with the ionic.Gestures.gesture options
      ionic.Gestures.utils.extend(ionic.Gestures.defaults, options, true);

      // set its index
      gesture.index = gesture.index || 1000;

      // add ionic.Gestures.gesture to the list
      this.gestures.push(gesture);

      // sort the list by index
      this.gestures.sort(function(a, b) {
        if (a.index < b.index) {
          return -1;
        }
        if (a.index > b.index) {
          return 1;
        }
        return 0;
      });

      return this.gestures;
    }
  };


  ionic.Gestures.gestures = ionic.Gestures.gestures || {};

  /**
   * Custom gestures
   * ==============================
   *
   * Gesture object
   * --------------------
   * The object structure of a gesture:
   *
   * { name: 'mygesture',
   *   index: 1337,
   *   defaults: {
   *     mygesture_option: true
   *   }
   *   handler: function(type, ev, inst) {
   *     // trigger gesture event
   *     inst.trigger(this.name, ev);
   *   }
   * }

   * @param   {String}    name
   * this should be the name of the gesture, lowercase
   * it is also being used to disable/enable the gesture per instance config.
   *
   * @param   {Number}    [index=1000]
   * the index of the gesture, where it is going to be in the stack of gestures detection
   * like when you build an gesture that depends on the drag gesture, it is a good
   * idea to place it after the index of the drag gesture.
   *
   * @param   {Object}    [defaults={}]
   * the default settings of the gesture. these are added to the instance settings,
   * and can be overruled per instance. you can also add the name of the gesture,
   * but this is also added by default (and set to true).
   *
   * @param   {Function}  handler
   * this handles the gesture detection of your custom gesture and receives the
   * following arguments:
   *
   *      @param  {Object}    eventData
   *      event data containing the following properties:
   *          timeStamp   {Number}        time the event occurred
   *          target      {HTMLElement}   target element
   *          touches     {Array}         touches (fingers, pointers, mouse) on the screen
   *          pointerType {String}        kind of pointer that was used. matches ionic.Gestures.POINTER_MOUSE|TOUCH
   *          center      {Object}        center position of the touches. contains pageX and pageY
   *          deltaTime   {Number}        the total time of the touches in the screen
   *          deltaX      {Number}        the delta on x axis we haved moved
   *          deltaY      {Number}        the delta on y axis we haved moved
   *          velocityX   {Number}        the velocity on the x
   *          velocityY   {Number}        the velocity on y
   *          angle       {Number}        the angle we are moving
   *          direction   {String}        the direction we are moving. matches ionic.Gestures.DIRECTION_UP|DOWN|LEFT|RIGHT
   *          distance    {Number}        the distance we haved moved
   *          scale       {Number}        scaling of the touches, needs 2 touches
   *          rotation    {Number}        rotation of the touches, needs 2 touches *
   *          eventType   {String}        matches ionic.Gestures.EVENT_START|MOVE|END
   *          srcEvent    {Object}        the source event, like TouchStart or MouseDown *
   *          startEvent  {Object}        contains the same properties as above,
   *                                      but from the first touch. this is used to calculate
   *                                      distances, deltaTime, scaling etc
   *
   *      @param  {ionic.Gestures.Instance}    inst
   *      the instance we are doing the detection for. you can get the options from
   *      the inst.options object and trigger the gesture event by calling inst.trigger
   *
   *
   * Handle gestures
   * --------------------
   * inside the handler you can get/set ionic.Gestures.detectionic.current. This is the current
   * detection sessionic. It has the following properties
   *      @param  {String}    name
   *      contains the name of the gesture we have detected. it has not a real function,
   *      only to check in other gestures if something is detected.
   *      like in the drag gesture we set it to 'drag' and in the swipe gesture we can
   *      check if the current gesture is 'drag' by accessing ionic.Gestures.detectionic.current.name
   *
   *      readonly
   *      @param  {ionic.Gestures.Instance}    inst
   *      the instance we do the detection for
   *
   *      readonly
   *      @param  {Object}    startEvent
   *      contains the properties of the first gesture detection in this sessionic.
   *      Used for calculations about timing, distance, etc.
   *
   *      readonly
   *      @param  {Object}    lastEvent
   *      contains all the properties of the last gesture detect in this sessionic.
   *
   * after the gesture detection session has been completed (user has released the screen)
   * the ionic.Gestures.detectionic.current object is copied into ionic.Gestures.detectionic.previous,
   * this is usefull for gestures like doubletap, where you need to know if the
   * previous gesture was a tap
   *
   * options that have been set by the instance can be received by calling inst.options
   *
   * You can trigger a gesture event by calling inst.trigger("mygesture", event).
   * The first param is the name of your gesture, the second the event argument
   *
   *
   * Register gestures
   * --------------------
   * When an gesture is added to the ionic.Gestures.gestures object, it is auto registered
   * at the setup of the first ionic.Gestures instance. You can also call ionic.Gestures.detectionic.register
   * manually and pass your gesture object as a param
   *
   */

  /**
   * Hold
   * Touch stays at the same place for x time
   * events  hold
   */
  ionic.Gestures.gestures.Hold = {
    name: 'hold',
    index: 10,
    defaults: {
      hold_timeout	: 500,
      hold_threshold	: 1
    },
    timer: null,
    handler: function holdGesture(ev, inst) {
      switch(ev.eventType) {
        case ionic.Gestures.EVENT_START:
          // clear any running timers
          clearTimeout(this.timer);

          // set the gesture so we can check in the timeout if it still is
          ionic.Gestures.detection.current.name = this.name;

          // set timer and if after the timeout it still is hold,
          // we trigger the hold event
          this.timer = setTimeout(function() {
            if(ionic.Gestures.detection.current.name == 'hold') {
              ionic.tap.cancelClick();
              inst.trigger('hold', ev);
            }
          }, inst.options.hold_timeout);
          break;

          // when you move or end we clear the timer
        case ionic.Gestures.EVENT_MOVE:
          if(ev.distance > inst.options.hold_threshold) {
            clearTimeout(this.timer);
          }
          break;

        case ionic.Gestures.EVENT_END:
          clearTimeout(this.timer);
          break;
      }
    }
  };


  /**
   * Tap/DoubleTap
   * Quick touch at a place or double at the same place
   * events  tap, doubletap
   */
  ionic.Gestures.gestures.Tap = {
    name: 'tap',
    index: 100,
    defaults: {
      tap_max_touchtime	: 250,
      tap_max_distance	: 10,
      tap_always			: true,
      doubletap_distance	: 20,
      doubletap_interval	: 300
    },
    handler: function tapGesture(ev, inst) {
      if(ev.eventType == ionic.Gestures.EVENT_END && ev.srcEvent.type != 'touchcancel') {
        // previous gesture, for the double tap since these are two different gesture detections
        var prev = ionic.Gestures.detection.previous,
        did_doubletap = false;

        // when the touchtime is higher then the max touch time
        // or when the moving distance is too much
        if(ev.deltaTime > inst.options.tap_max_touchtime ||
            ev.distance > inst.options.tap_max_distance) {
              return;
            }

        // check if double tap
        if(prev && prev.name == 'tap' &&
            (ev.timeStamp - prev.lastEvent.timeStamp) < inst.options.doubletap_interval &&
            ev.distance < inst.options.doubletap_distance) {
              inst.trigger('doubletap', ev);
              did_doubletap = true;
            }

        // do a single tap
        if(!did_doubletap || inst.options.tap_always) {
          ionic.Gestures.detection.current.name = 'tap';
          inst.trigger('tap', ev);
        }
      }
    }
  };


  /**
   * Swipe
   * triggers swipe events when the end velocity is above the threshold
   * events  swipe, swipeleft, swiperight, swipeup, swipedown
   */
  ionic.Gestures.gestures.Swipe = {
    name: 'swipe',
    index: 40,
    defaults: {
      // set 0 for unlimited, but this can conflict with transform
      swipe_max_touches  : 1,
      swipe_velocity     : 0.7
    },
    handler: function swipeGesture(ev, inst) {
      if(ev.eventType == ionic.Gestures.EVENT_END) {
        // max touches
        if(inst.options.swipe_max_touches > 0 &&
            ev.touches.length > inst.options.swipe_max_touches) {
              return;
            }

        // when the distance we moved is too small we skip this gesture
        // or we can be already in dragging
        if(ev.velocityX > inst.options.swipe_velocity ||
            ev.velocityY > inst.options.swipe_velocity) {
              // trigger swipe events
              inst.trigger(this.name, ev);
              inst.trigger(this.name + ev.direction, ev);
            }
      }
    }
  };


  /**
   * Drag
   * Move with x fingers (default 1) around on the page. Blocking the scrolling when
   * moving left and right is a good practice. When all the drag events are blocking
   * you disable scrolling on that area.
   * events  drag, drapleft, dragright, dragup, dragdown
   */
  ionic.Gestures.gestures.Drag = {
    name: 'drag',
    index: 50,
    defaults: {
      drag_min_distance : 10,
      // Set correct_for_drag_min_distance to true to make the starting point of the drag
      // be calculated from where the drag was triggered, not from where the touch started.
      // Useful to avoid a jerk-starting drag, which can make fine-adjustments
      // through dragging difficult, and be visually unappealing.
      correct_for_drag_min_distance : true,
      // set 0 for unlimited, but this can conflict with transform
      drag_max_touches  : 1,
      // prevent default browser behavior when dragging occurs
      // be careful with it, it makes the element a blocking element
      // when you are using the drag gesture, it is a good practice to set this true
      drag_block_horizontal   : true,
      drag_block_vertical     : true,
      // drag_lock_to_axis keeps the drag gesture on the axis that it started on,
      // It disallows vertical directions if the initial direction was horizontal, and vice versa.
      drag_lock_to_axis       : false,
      // drag lock only kicks in when distance > drag_lock_min_distance
      // This way, locking occurs only when the distance has become large enough to reliably determine the direction
      drag_lock_min_distance : 25
    },
    triggered: false,
    handler: function dragGesture(ev, inst) {
      // current gesture isnt drag, but dragged is true
      // this means an other gesture is busy. now call dragend
      if(ionic.Gestures.detection.current.name != this.name && this.triggered) {
        inst.trigger(this.name +'end', ev);
        this.triggered = false;
        return;
      }

      // max touches
      if(inst.options.drag_max_touches > 0 &&
          ev.touches.length > inst.options.drag_max_touches) {
            return;
          }

      switch(ev.eventType) {
        case ionic.Gestures.EVENT_START:
          this.triggered = false;
          break;

        case ionic.Gestures.EVENT_MOVE:
          // when the distance we moved is too small we skip this gesture
          // or we can be already in dragging
          if(ev.distance < inst.options.drag_min_distance &&
              ionic.Gestures.detection.current.name != this.name) {
                return;
              }

          // we are dragging!
          if(ionic.Gestures.detection.current.name != this.name) {
            ionic.Gestures.detection.current.name = this.name;
            if (inst.options.correct_for_drag_min_distance) {
              // When a drag is triggered, set the event center to drag_min_distance pixels from the original event center.
              // Without this correction, the dragged distance would jumpstart at drag_min_distance pixels instead of at 0.
              // It might be useful to save the original start point somewhere
              var factor = Math.abs(inst.options.drag_min_distance/ev.distance);
              ionic.Gestures.detection.current.startEvent.center.pageX += ev.deltaX * factor;
              ionic.Gestures.detection.current.startEvent.center.pageY += ev.deltaY * factor;

              // recalculate event data using new start point
              ev = ionic.Gestures.detection.extendEventData(ev);
            }
          }

          // lock drag to axis?
          if(ionic.Gestures.detection.current.lastEvent.drag_locked_to_axis || (inst.options.drag_lock_to_axis && inst.options.drag_lock_min_distance<=ev.distance)) {
            ev.drag_locked_to_axis = true;
          }
          var last_direction = ionic.Gestures.detection.current.lastEvent.direction;
          if(ev.drag_locked_to_axis && last_direction !== ev.direction) {
            // keep direction on the axis that the drag gesture started on
            if(ionic.Gestures.utils.isVertical(last_direction)) {
              ev.direction = (ev.deltaY < 0) ? ionic.Gestures.DIRECTION_UP : ionic.Gestures.DIRECTION_DOWN;
            }
            else {
              ev.direction = (ev.deltaX < 0) ? ionic.Gestures.DIRECTION_LEFT : ionic.Gestures.DIRECTION_RIGHT;
            }
          }

          // first time, trigger dragstart event
          if(!this.triggered) {
            inst.trigger(this.name +'start', ev);
            this.triggered = true;
          }

          // trigger normal event
          inst.trigger(this.name, ev);

          // direction event, like dragdown
          inst.trigger(this.name + ev.direction, ev);

          // block the browser events
          if( (inst.options.drag_block_vertical && ionic.Gestures.utils.isVertical(ev.direction)) ||
              (inst.options.drag_block_horizontal && !ionic.Gestures.utils.isVertical(ev.direction))) {
                ev.preventDefault();
              }
          break;

        case ionic.Gestures.EVENT_END:
          // trigger dragend
          if(this.triggered) {
            inst.trigger(this.name +'end', ev);
          }

          this.triggered = false;
          break;
      }
    }
  };


  /**
   * Transform
   * User want to scale or rotate with 2 fingers
   * events  transform, pinch, pinchin, pinchout, rotate
   */
  ionic.Gestures.gestures.Transform = {
    name: 'transform',
    index: 45,
    defaults: {
      // factor, no scale is 1, zoomin is to 0 and zoomout until higher then 1
      transform_min_scale     : 0.01,
      // rotation in degrees
      transform_min_rotation  : 1,
      // prevent default browser behavior when two touches are on the screen
      // but it makes the element a blocking element
      // when you are using the transform gesture, it is a good practice to set this true
      transform_always_block  : false
    },
    triggered: false,
    handler: function transformGesture(ev, inst) {
      // current gesture isnt drag, but dragged is true
      // this means an other gesture is busy. now call dragend
      if(ionic.Gestures.detection.current.name != this.name && this.triggered) {
        inst.trigger(this.name +'end', ev);
        this.triggered = false;
        return;
      }

      // atleast multitouch
      if(ev.touches.length < 2) {
        return;
      }

      // prevent default when two fingers are on the screen
      if(inst.options.transform_always_block) {
        ev.preventDefault();
      }

      switch(ev.eventType) {
        case ionic.Gestures.EVENT_START:
          this.triggered = false;
          break;

        case ionic.Gestures.EVENT_MOVE:
          var scale_threshold = Math.abs(1-ev.scale);
          var rotation_threshold = Math.abs(ev.rotation);

          // when the distance we moved is too small we skip this gesture
          // or we can be already in dragging
          if(scale_threshold < inst.options.transform_min_scale &&
              rotation_threshold < inst.options.transform_min_rotation) {
                return;
              }

          // we are transforming!
          ionic.Gestures.detection.current.name = this.name;

          // first time, trigger dragstart event
          if(!this.triggered) {
            inst.trigger(this.name +'start', ev);
            this.triggered = true;
          }

          inst.trigger(this.name, ev); // basic transform event

          // trigger rotate event
          if(rotation_threshold > inst.options.transform_min_rotation) {
            inst.trigger('rotate', ev);
          }

          // trigger pinch event
          if(scale_threshold > inst.options.transform_min_scale) {
            inst.trigger('pinch', ev);
            inst.trigger('pinch'+ ((ev.scale < 1) ? 'in' : 'out'), ev);
          }
          break;

        case ionic.Gestures.EVENT_END:
          // trigger dragend
          if(this.triggered) {
            inst.trigger(this.name +'end', ev);
          }

          this.triggered = false;
          break;
      }
    }
  };


  /**
   * Touch
   * Called as first, tells the user has touched the screen
   * events  touch
   */
  ionic.Gestures.gestures.Touch = {
    name: 'touch',
    index: -Infinity,
    defaults: {
      // call preventDefault at touchstart, and makes the element blocking by
      // disabling the scrolling of the page, but it improves gestures like
      // transforming and dragging.
      // be careful with using this, it can be very annoying for users to be stuck
      // on the page
      prevent_default: false,

      // disable mouse events, so only touch (or pen!) input triggers events
      prevent_mouseevents: false
    },
    handler: function touchGesture(ev, inst) {
      if(inst.options.prevent_mouseevents && ev.pointerType == ionic.Gestures.POINTER_MOUSE) {
        ev.stopDetect();
        return;
      }

      if(inst.options.prevent_default) {
        ev.preventDefault();
      }

      if(ev.eventType ==  ionic.Gestures.EVENT_START) {
        inst.trigger(this.name, ev);
      }
    }
  };


  /**
   * Release
   * Called as last, tells the user has released the screen
   * events  release
   */
  ionic.Gestures.gestures.Release = {
    name: 'release',
    index: Infinity,
    handler: function releaseGesture(ev, inst) {
      if(ev.eventType ==  ionic.Gestures.EVENT_END) {
        inst.trigger(this.name, ev);
      }
    }
  };
})(window.ionic);