[C#]	public event System.EventHandler ViewPortChanged;
[VB]	Public Event ViewPortChanged As System.EventHandler

This event occurs when the viewport is changed by mouse actions in the browser side Javascript ChartViewer (JsChartViewer).

To fire this event, the JsChartViewer should be used on the browser side, and it should not be configured to use partial chart updates (AJAX updates). If partial chart updates are used, instead of firing the ViewPortChanged event, AJAX based requests will be sent to the server side instead.