openlayers/src/ol/pointer/mousesource.js

// Based on https://github.com/Polymer/PointerEvents

// Copyright (c) 2013 The Polymer Authors. All rights reserved.
//
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// modification, are permitted provided that the following conditions are
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goog.provide('ol.pointer.MouseSource');

goog.require('ol.pointer.EventSource');


/**
 * @param {ol.pointer.PointerEventHandler} dispatcher Event handler.
 * @constructor
 * @extends {ol.pointer.EventSource}
 */
ol.pointer.MouseSource = function(dispatcher) {
  var mapping = {
    'mousedown': this.mousedown,
    'mousemove': this.mousemove,
    'mouseup': this.mouseup,
    'mouseover': this.mouseover,
    'mouseout': this.mouseout
  };
  goog.base(this, dispatcher, mapping);

  /**
   * @const
   * @type {!Object.<string, goog.events.BrowserEvent|Object>}
   */
  this.pointerMap = dispatcher.pointerMap;

  /**
   * @const
   * @type {Array.<ol.Pixel>}
   */
  this.lastTouches = [];
};
goog.inherits(ol.pointer.MouseSource, ol.pointer.EventSource);


/**
 * @const
 * @type {number}
 */
ol.pointer.MouseSource.POINTER_ID = 1;


/**
 * @const
 * @type {string}
 */
ol.pointer.MouseSource.POINTER_TYPE = 'mouse';


/**
 * Radius around touchend that swallows mouse events.
 *
 * @const
 * @type {number}
 */
ol.pointer.MouseSource.DEDUP_DIST = 25;


/**
 * Detect if a mouse event was simulated from a touch by
 * checking if previously there was a touch event at the
 * same position.
 *
 * FIXME - Known problem with the native Android browser on
 * Samsung GT-I9100 (Android 4.1.2):
 * In case the page is scrolled, this function does not work
 * correctly when a canvas is used (WebGL or canvas renderer).
 * Mouse listeners on canvas elements (for this browser), create
 * two mouse events: One 'good' and one 'bad' one (on other browsers or
 * when a div is used, there is only one event). For the 'bad' one,
 * clientX/clientY and also pageX/pageY are wrong when the page
 * is scrolled. Because of that, this function can not detect if
 * the events were simulated from a touch event. As result, a
 * pointer event at a wrong position is dispatched, which confuses
 * the map interactions.
 * It is unclear, how one can get the correct position for the event
 * or detect that the positions are invalid.
 *
 * @private
 * @param {goog.events.BrowserEvent} inEvent The in event.
 * @return {boolean} True, if the event was generated by a touch.
 */
ol.pointer.MouseSource.prototype.isEventSimulatedFromTouch_ = function(inEvent) {
  var lts = this.lastTouches;
  var x = inEvent.clientX, y = inEvent.clientY;
  for (var i = 0, l = lts.length, t; i < l && (t = lts[i]); i++) {
    // simulated mouse events will be swallowed near a primary touchend
    var dx = Math.abs(x - t[0]), dy = Math.abs(y - t[1]);
    if (dx <= ol.pointer.MouseSource.DEDUP_DIST &&
        dy <= ol.pointer.MouseSource.DEDUP_DIST) {
      return true;
    }
  }
  return false;
};


/**
 * Creates a copy of the original event that will be used
 * for the fake pointer event.
 *
 * @param {goog.events.BrowserEvent} inEvent The in event.
 * @param {ol.pointer.PointerEventHandler} dispatcher Event handler.
 * @return {Object} The copied event.
 */
ol.pointer.MouseSource.prepareEvent = function(inEvent, dispatcher) {
  var e = dispatcher.cloneEvent(inEvent, inEvent.getBrowserEvent());

  // forward mouse preventDefault
  var pd = e.preventDefault;
  e.preventDefault = function() {
    inEvent.preventDefault();
    pd();
  };

  e.pointerId = ol.pointer.MouseSource.POINTER_ID;
  e.isPrimary = true;
  e.pointerType = ol.pointer.MouseSource.POINTER_TYPE;

  return e;
};


/**
 * Handler for `mousedown`.
 *
 * @param {goog.events.BrowserEvent} inEvent The in event.
 */
ol.pointer.MouseSource.prototype.mousedown = function(inEvent) {
  if (!this.isEventSimulatedFromTouch_(inEvent)) {
    // TODO(dfreedman) workaround for some elements not sending mouseup
    // http://crbug/149091
    if (ol.pointer.MouseSource.POINTER_ID.toString() in this.pointerMap) {
      this.cancel(inEvent);
    }
    var e = ol.pointer.MouseSource.prepareEvent(inEvent, this.dispatcher);
    this.pointerMap[ol.pointer.MouseSource.POINTER_ID.toString()] = inEvent;
    this.dispatcher.down(e, inEvent);
  }
};


/**
 * Handler for `mousemove`.
 *
 * @param {goog.events.BrowserEvent} inEvent The in event.
 */
ol.pointer.MouseSource.prototype.mousemove = function(inEvent) {
  if (!this.isEventSimulatedFromTouch_(inEvent)) {
    var e = ol.pointer.MouseSource.prepareEvent(inEvent, this.dispatcher);
    this.dispatcher.move(e, inEvent);
  }
};


/**
 * Handler for `mouseup`.
 *
 * @param {goog.events.BrowserEvent} inEvent The in event.
 */
ol.pointer.MouseSource.prototype.mouseup = function(inEvent) {
  if (!this.isEventSimulatedFromTouch_(inEvent)) {
    var p = this.pointerMap[ol.pointer.MouseSource.POINTER_ID.toString()];

    if (p && p.button === inEvent.button) {
      var e = ol.pointer.MouseSource.prepareEvent(inEvent, this.dispatcher);
      this.dispatcher.up(e, inEvent);
      this.cleanupMouse();
    }
  }
};


/**
 * Handler for `mouseover`.
 *
 * @param {goog.events.BrowserEvent} inEvent The in event.
 */
ol.pointer.MouseSource.prototype.mouseover = function(inEvent) {
  if (!this.isEventSimulatedFromTouch_(inEvent)) {
    var e = ol.pointer.MouseSource.prepareEvent(inEvent, this.dispatcher);
    this.dispatcher.enterOver(e, inEvent);
  }
};


/**
 * Handler for `mouseout`.
 *
 * @param {goog.events.BrowserEvent} inEvent The in event.
 */
ol.pointer.MouseSource.prototype.mouseout = function(inEvent) {
  if (!this.isEventSimulatedFromTouch_(inEvent)) {
    var e = ol.pointer.MouseSource.prepareEvent(inEvent, this.dispatcher);
    this.dispatcher.leaveOut(e, inEvent);
  }
};


/**
 * Dispatches a `pointercancel` event.
 *
 * @param {goog.events.BrowserEvent} inEvent The in event.
 */
ol.pointer.MouseSource.prototype.cancel = function(inEvent) {
  var e = ol.pointer.MouseSource.prepareEvent(inEvent, this.dispatcher);
  this.dispatcher.cancel(e, inEvent);
  this.cleanupMouse();
};


/**
 * Remove the mouse from the list of active pointers.
 */
ol.pointer.MouseSource.prototype.cleanupMouse = function() {
  delete this.pointerMap[ol.pointer.MouseSource.POINTER_ID.toString()];
};