# all files / ol/interaction/ mousewheelzoominteraction.js

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75% Branches 21/28
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     goog.provide('ol.interaction.MouseWheelZoom');

    goog.require('goog.asserts');
    goog.require('ol');
    goog.require('ol.Coordinate');
    goog.require('ol.events.EventType');
    goog.require('ol.interaction.Interaction');
    goog.require('ol.math');

    /**
     * @classdesc
     * Allows the user to zoom the map by scrolling the mouse wheel.
     *
     * @constructor
     * @extends {ol.interaction.Interaction}
     * @param {olx.interaction.MouseWheelZoomOptions=} opt_options Options.
     * @api stable
     */
    ol.interaction.MouseWheelZoom = function(opt_options) {

      goog.base(this, {
        handleEvent: ol.interaction.MouseWheelZoom.handleEvent
      });

      var options = opt_options || {};

      /**
       * @private
       * @type {number}
       */
      this.delta_ = 0;

      /**
       * @private
       * @type {number}
       */
      this.duration_ = options.duration !== undefined ? options.duration : 250;

      /**
       * @private
       * @type {boolean}
       */
      this.useAnchor_ = options.useAnchor !== undefined ? options.useAnchor : true;

      /**
       * @private
       * @type {?ol.Coordinate}
       */
      this.lastAnchor_ = null;

      /**
       * @private
       * @type {number|undefined}
       */
      this.startTime_ = undefined;

      /**
       * @private
       * @type {number|undefined}
       */
      this.timeoutId_ = undefined;

    };
    goog.inherits(ol.interaction.MouseWheelZoom, ol.interaction.Interaction);

    /**
     * Handles the {@link ol.MapBrowserEvent map browser event} (if it was a
     * mousewheel-event) and eventually zooms the map.
     * @param {ol.MapBrowserEvent} mapBrowserEvent Map browser event.
     * @return {boolean} `false` to stop event propagation.
     * @this {ol.interaction.MouseWheelZoom}
     * @api
     */
    ol.interaction.MouseWheelZoom.handleEvent = function(mapBrowserEvent) {
      var stopEvent = false;
      if (mapBrowserEvent.type == ol.events.EventType.WHEEL ||
          mapBrowserEvent.type == ol.events.EventType.MOUSEWHEEL) {
        var map = mapBrowserEvent.map;
        var wheelEvent = /** @type {WheelEvent} */ (mapBrowserEvent.originalEvent);

        Eif (this.useAnchor_) {
          this.lastAnchor_ = mapBrowserEvent.coordinate;
        }

        // Delta normalisation inspired by
        // https://github.com/mapbox/mapbox-gl-js/blob/001c7b9/js/ui/handler/scroll_zoom.js
        //TODO There's more good stuff in there for inspiration to improve this interaction.
        var delta;
        if (mapBrowserEvent.type == ol.events.EventType.WHEEL) {
          delta = wheelEvent.deltaY;
          if (ol.has.FIREFOX &&
              wheelEvent.deltaMode === goog.global.WheelEvent.DOM_DELTA_PIXEL) {
            delta /= ol.has.DEVICE_PIXEL_RATIO;
          }
          if (wheelEvent.deltaMode === goog.global.WheelEvent.DOM_DELTA_LINE) {
            delta *= 40;
          }
        } else Eif (mapBrowserEvent.type == ol.events.EventType.MOUSEWHEEL) {
          delta = -wheelEvent.wheelDeltaY;
          if (ol.has.SAFARI) {
            delta /= 3;
          }
        }

        this.delta_ += delta;

        Eif (this.startTime_ === undefined) {
          this.startTime_ = Date.now();
        }

        var duration = ol.MOUSEWHEELZOOM_TIMEOUT_DURATION;
        var timeLeft = Math.max(duration - (Date.now() - this.startTime_), 0);

        goog.global.clearTimeout(this.timeoutId_);
        this.timeoutId_ = goog.global.setTimeout(
            this.doZoom_.bind(this, map), timeLeft);

        mapBrowserEvent.preventDefault();
        stopEvent = true;
      }
      return !stopEvent;
    };

    /**
     * @private
     * @param {ol.Map} map Map.
     */
    ol.interaction.MouseWheelZoom.prototype.doZoom_ = function(map) {
      var maxDelta = ol.MOUSEWHEELZOOM_MAXDELTA;
      var delta = ol.math.clamp(this.delta_, -maxDelta, maxDelta);

      var view = map.getView();
      goog.asserts.assert(view, 'map must have view');

      map.render();
      ol.interaction.Interaction.zoomByDelta(map, view, -delta, this.lastAnchor_,
          this.duration_);

      this.delta_ = 0;
      this.lastAnchor_ = null;
      this.startTime_ = undefined;
      this.timeoutId_ = undefined;
    };

    /**
     * Enable or disable using the mouse's location as an anchor when zooming
     * @param {boolean} useAnchor true to zoom to the mouse's location, false
     * to zoom to the center of the map
     * @api
     */
    ol.interaction.MouseWheelZoom.prototype.setMouseAnchor = function(useAnchor) {
      this.useAnchor_ = useAnchor;
      Eif (!useAnchor) {
        this.lastAnchor_ = null;
      }
    };