Bounded back/forward navigation history, used for image and map view history. Recording after stepping back discards the forward entries; consecutive equal entries are recorded once.
Recorded view state.
Whether no entry has been recorded since construction or the last clear.
Maximum retained entries; the oldest entry is dropped first.
Entry equality used to skip duplicate consecutive entries.
Forget every entry.
Record a new current entry.
Move back (-1) or forward (1), returning the new current entry or undefined at an end.
Bounded back/forward navigation history, used for image and map view history. Recording after stepping back discards the forward entries; consecutive equal entries are recorded once.