vaadin timeline zoom level click listener

How do I detect which zoom level clicked by user in vaadin timeline by a click listener?

zoom levels are added in following manner.
timeline.addZoomLevel("Day", 86400000L); timeline.addZoomLevel("Week", 7 * 86400000L); timeline.addZoomLevel("Month", 2629743830L); timeline.addZoomLevel("3 Months", 3 * 2629743830L); timeline.addZoomLevel("1 Year", 31556926000L); timeline.addZoomLevel("5 Year", 5 * 31556926000L); The following date range listner fires when a user clicks on a zoom level and also when date range changed, but i cannot find which zoom level clicked by the user.(eg:- Day, Week, Month, etc.)
timeline.addListener(new Timeline.DateRangeListener() { @Override public void dateRangeChanged(DateRangeChangedEvent event) { System.out.println("DateRangeChangedEvent Fired!"); } });

The DateRangeListener is only fired when you visible area of the graph you are viewing has changed. When you change the zoom level the visible area changes, and so the DateRangeListener is fired.

Unfortunaly there does not exist a zoom level changed listener you could use, changing the zoom level is a client side only operation at the moment.

You might be able to use the DateRangeChangedEvent to calculate the zoom level however. If you calculate event.getEndDate().getTime() - event.getStartDate().getTime() you should get the approximate zoom level. It is not exact though, as the client side Timeline does some adjustments to the shown graph after the zoom is set.