text: goog.provide('ol.control.Zoom');
  
  goog.require('goog.asserts');
  goog.require('goog.dom');
  goog.require('goog.dom.TagName');
  goog.require('goog.events');
  goog.require('goog.events.EventType');
  goog.require('ol.animation');
  goog.require('ol.control.Control');
  goog.require('ol.css');
  goog.require('ol.easing');
  goog.require('ol.pointer.PointerEventHandler');
  
  
  
  /**
   * @classdesc
   * A control with 2 buttons, one for zoom in and one for zoom out.
   * This control is one of the default controls of a map. To style this control
   * use css selectors `.ol-zoom-in` and `.ol-zoom-out`.
   *
   * @constructor
   * @extends {ol.control.Control}
   * @param {olx.control.ZoomOptions=} opt_options Zoom options.
   * @api
   */
  ol.control.Zoom = function(opt_options) {
  
    var options = goog.isDef(opt_options) ? opt_options : {};
  
    var className = goog.isDef(options.className) ? options.className : 'ol-zoom';
  
    var delta = goog.isDef(options.delta) ? options.delta : 1;
  
    var zoomInLabel = goog.isDef(options.zoomInLabel) ?
        options.zoomInLabel : '+';
    var zoomOutLabel = goog.isDef(options.zoomOutLabel) ?
        options.zoomOutLabel : '\u2212';
  
    var zoomInTipLabel = goog.isDef(options.zoomInTipLabel) ?
        options.zoomInTipLabel : 'Zoom in';
    var zoomOutTipLabel = goog.isDef(options.zoomOutTipLabel) ?
        options.zoomOutTipLabel : 'Zoom out';
  
    var tTipZoomIn = goog.dom.createDom(goog.dom.TagName.SPAN, {
      'role' : 'tooltip'
    }, zoomInTipLabel);
    var inElement = goog.dom.createDom(goog.dom.TagName.BUTTON, {
      'class': className + '-in ol-has-tooltip',
      'type' : 'button'
    }, tTipZoomIn, zoomInLabel);
  
    var inElementHandler = new ol.pointer.PointerEventHandler(inElement);
    this.registerDisposable(inElementHandler);
    goog.events.listen(inElementHandler,
        ol.pointer.EventType.POINTERUP, goog.partial(
            ol.control.Zoom.prototype.handlePointerUp_, delta), false, this);
    goog.events.listen(inElement,
        goog.events.EventType.CLICK, goog.partial(
            ol.control.Zoom.prototype.handleClick_, delta), false, this);
  
    goog.events.listen(inElement, [
      goog.events.EventType.MOUSEOUT,
      goog.events.EventType.FOCUSOUT
    ], function() {
      this.blur();
    }, false);
  
    var tTipsZoomOut = goog.dom.createDom(goog.dom.TagName.SPAN, {
      'role' : 'tooltip'
    }, zoomOutTipLabel);
    var outElement = goog.dom.createDom(goog.dom.TagName.BUTTON, {
      'class': className + '-out  ol-has-tooltip',
      'type' : 'button'
    }, tTipsZoomOut, zoomOutLabel);
  
    var outElementHandler = new ol.pointer.PointerEventHandler(outElement);
    this.registerDisposable(outElementHandler);
    goog.events.listen(outElementHandler,
        ol.pointer.EventType.POINTERUP, goog.partial(
            ol.control.Zoom.prototype.handlePointerUp_, -delta), false, this);
    goog.events.listen(outElement,
        goog.events.EventType.CLICK, goog.partial(
            ol.control.Zoom.prototype.handleClick_, -delta), false, this);
  
    goog.events.listen(outElement, [
      goog.events.EventType.MOUSEOUT,
      goog.events.EventType.FOCUSOUT
    ], function() {
      this.blur();
    }, false);
  
    var cssClasses = className + ' ' + ol.css.CLASS_UNSELECTABLE + ' ' +
        ol.css.CLASS_CONTROL;
    var element = goog.dom.createDom(goog.dom.TagName.DIV, cssClasses, inElement,
        outElement);
  
    goog.base(this, {
      element: element,
      target: options.target
    });
  
    /**
     * @type {number}
     * @private
     */
    this.duration_ = goog.isDef(options.duration) ? options.duration : 250;
  
  };
  goog.inherits(ol.control.Zoom, ol.control.Control);
  
  
  /**
   * @param {number} delta Zoom delta.
   * @param {goog.events.BrowserEvent} event The event to handle
   * @private
   */
  ol.control.Zoom.prototype.handleClick_ = function(delta, event) {
    if (event.screenX !== 0 && event.screenY !== 0) {
      return;
    }
    this.zoomByDelta_(delta);
  };
  
  
  /**
   * @param {number} delta Zoom delta.
   * @param {ol.pointer.PointerEvent} pointerEvent The event to handle
   * @private
   */
  ol.control.Zoom.prototype.handlePointerUp_ = function(delta, pointerEvent) {
    pointerEvent.browserEvent.preventDefault();
    this.zoomByDelta_(delta);
  };
  
  
  /**
   * @param {number} delta Zoom delta.
   * @private
   */
  ol.control.Zoom.prototype.zoomByDelta_ = function(delta) {
    var map = this.getMap();
    var view = map.getView();
    var currentResolution = view.getResolution();
    if (goog.isDef(currentResolution)) {
      if (this.duration_ > 0) {
        map.beforeRender(ol.animation.zoom({
          resolution: currentResolution,
          duration: this.duration_,
          easing: ol.easing.easeOut
        }));
      }
      var newResolution = view.constrainResolution(currentResolution, delta);
      view.setResolution(newResolution);
    }
  };
  