public EntityPlacementControlViewModel(EntityPlacement placement, EntityInfo entityInfo, ScreenDocument screen)
{
if (placement == null)
throw new ArgumentNullException("placement");
if (entityInfo == null)
throw new ArgumentNullException("entityInfo");
if (screen == null)
throw new ArgumentNullException("screen");
this.Placement = placement;
this._entityInfo = entityInfo;
this._screen = screen;
DeleteCommand = new RelayCommand(Delete);
FlipCommand = new RelayCommand(Flip);
RespawnCommand = new RelayCommand(SetRespawnMode);
StartStateCommand = new RelayCommand(SetStartState);
ViewModelMediator.Current.GetEvent<ZoomChangedEventArgs>().Subscribe(ZoomChanged);
}