Make touch zoom animation duration configurable

src/objectliterals.jsdoc

@@ -343,6 +343,11 @@
  * @property {number|undefined} threshold Minimal angle to start a rotation.
  */
 
+/**
+ * @typedef {Object} ol.interaction.TouchZoomOptions
+ * @property {number|undefined} duration Animation duration. Default is 400ms.
+ */
+
 /**
  * @typedef {Object} ol.layer.BaseOptions
  * @property {number|undefined} brightness Brightness.

src/ol/interaction/touchzoominteraction.js

@@ -9,20 +9,17 @@ goog.require('ol.interaction.Interaction');
 goog.require('ol.interaction.Touch');
 
 
-/**
- * @define {number} Animation duration.
- */
-ol.interaction.TOUCHZOOM_ANIMATION_DURATION = 400;
-
-
 
 /**
  * Allows the user to zoom the map by pinching with two fingers
  * on a touch screen.
  * @constructor
  * @extends {ol.interaction.Touch}
+ * @param {ol.interaction.TouchZoomOptions=} opt_options Options.
  */
-ol.interaction.TouchZoom = function() {
+ol.interaction.TouchZoom = function(opt_options) {
+
+  var options = goog.isDef(opt_options) ? opt_options : {};
 
   goog.base(this);
 
@@ -32,6 +29,12 @@ ol.interaction.TouchZoom = function() {
    */
   this.anchor_ = null;
 
+  /**
+   * @private
+   * @type {number}
+   */
+  this.duration_ = goog.isDef(options.duration) ? options.duration : 400;
+
   /**
    * @private
    * @type {number|undefined}
@@ -107,7 +110,7 @@ ol.interaction.TouchZoom.prototype.handleTouchEnd =
     // Direction is > 0 if pinching out, and < 0 if pinching in.
     var direction = this.lastScaleDelta_ - 1;
     ol.interaction.Interaction.zoom(map, view, view2DState.resolution,
-        this.anchor_, ol.interaction.TOUCHZOOM_ANIMATION_DURATION, direction);
+        this.anchor_, this.duration_, direction);
     return false;
   } else {
     return true;