// refresh the DataContext of the tree view if the underlying view model changes
private void OnViewModelChange(object sender, ExplorerViewModelHelper.ExplorerViewModelChangedEventArgs args)
{
var viewModel = args.NewViewModel;
Debug.Assert(viewModel != null, "Null ViewModel in ExplorerFrame.OnViewModelChange()");
Debug.Assert(viewModel.RootNode != null, "Null ViewModel.RootNode in ExplorerFrame.OnViewModelChange()");
ExplorerTreeView.DataContext = viewModel.RootNode;
}
private void ReloadViewModel()
{
Debug.Assert(_context != null, "ExplorerFrame was disposed");
// if _viewModelHelper doesn't exist then create and subscribe to ViewModelChanged event
if (_viewModelHelper == null)
{
_viewModelHelper = GetNewExplorerViewModelHelper();
_viewModelHelper.ExplorerViewModelChanged += OnViewModelChange;
}
// create a new ViewModel and assign it to the ViewModelHelper - this
// will cause ViewModelChanged event to be fired and we will update
// the DataContext in OnViewModelChange() below
_viewModelHelper.CreateViewModel(_context);
}
