Previous Extent/Next Extent Functionality

[VishnuB]

How to implement previous extent and next extent functionality in ArcGIS Runtime for Qt? I tried to implement using viewpoint changed event. Bookmarking the current viewpoint in every viewpoint changed event, But viewpoint changed event gets triggered two times when the viewpoint changes. Is there any API's available for this functionality or else please share some logic to implement this functionality. 

[LucasDanzinger]

there's no API for this specifically - you'd need to create some sort of data structure that keeps track of this and has certain rules, such as no duplicates and must be a certain tolerance difference from the previous bookmark, or something along those lines.