public void NavigationStack_IsEmptyCollection()
{
NavigationState state = new NavigationState();
Assert.IsNotNull(state.NavigationStack);
Assert.AreEqual(0, state.NavigationStack.Count);
}
protected NavigationState StoreState()
{
// Create an object for storage of the navigation state
NavigationState state = new NavigationState();
// Enumerate all NavigationEntries in the navigation stack
foreach (NavigationEntry entry in NavigationStack)
{
// Save the page state
// TODO : Do this when navigating away from each page to save time when suspending
SavePageState(entry);
// Create an object for storage of this entry
NavigationEntryState entryState = new NavigationEntryState(entry.PageName, entry.ArgumentsData, entry.StateData);
state.NavigationStack.Add(entryState);
}
// Return the result
return state;
}
protected void RestoreState(NavigationState state)
{
if (state == null)
throw new ArgumentNullException(nameof(state));
// Restore the navigation stack
// NB: Flag that we are restoring state so we can pass a NavigationMode.Refresh to restored pages
_restoringState = true;
try
{
NavigationStack.Push(state.NavigationStack);
}
finally
{
_restoringState = false;
}
}
protected void RestoreState(NavigationState state)
{
foreach (NavigationEntryState entryState in state.NavigationStack.Reverse())
{
// Push the restored navigation entry onto the stack
NavigationStack.Push(new NavigationEntry(entryState.PageName, entryState.ArgumentsData, entryState.StateData));
}
// Display the last page in the stack
DisplayNavigationEntry(CurrentPage);
// Call NavigatedTo() on the restored page
CallNavigatedTo(CurrentPage, NavigationMode.Refresh);
}
protected NavigationState StoreState()
{
// Create an object for storage of the navigation state
NavigationState state = new NavigationState();
// Enumerate all NavigationEntries in the navigation stack
foreach (PageInfo pageInfo in NavigationStack)
{
// If the view model is IActivatable then use this to save the page state
// NB: First check that the view has been created - this may still have state from a previous instance
PageDetails pageDetails;
if (_pageCache.TryGetValue(pageInfo, out pageDetails))
{
object viewModel = pageDetails.ViewLifetimeContext.ViewModel;
if (viewModel is IActivatable)
((IActivatable)viewModel).SaveState(pageInfo);
}
// Add to the navigation state
state.NavigationStack.Add(pageInfo);
}
// Return the result
return state;
}