init method
Implementation
void init(List<SSBottomNavItem> items, {SSBottomNavBarSettings? settings}) {
this.settings = settings;
this.items = items;
sizes = this.items.map((e) => Offset.zero).toList();
sizesBig = this.items.map((e) => Offset.zero).toList();
positions = this.items.map((e) => Offset.zero).toList();
positionsBig = this.items.map((e) => Offset.zero).toList();
keys = this.items.map((e) => GlobalKey()).toList();
}