/// <summary>
/// Ensures the nav menu reflects reality when navigation is triggered outside of
/// the nav menu buttons.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnNavigatingToPage(object sender, NavigatingCancelEventArgs e)
{
var snooStreamViewModel = Application.Current.Resources["SnooStream"] as SnooStreamViewModel;
if (SnooStreamViewModel.NavigationService == null)
{
var navService = new NavigationService(AppFrame, snooStreamViewModel);
SnooStreamViewModel.NavigationService = navService;
navService.Finish(snooStreamViewModel.GetNavigationBlob());
}
var navVM = ((SnooStreamViewModel)App.Current.Resources["SnooStream"]).NavMenu;
if (e.NavigationMode == NavigationMode.Back)
{
var item = (from p in navVM.Items where MapVMToPageType(p.VM) == e.SourcePageType select p).SingleOrDefault();
if (item == null && this.AppFrame.BackStackDepth > 0)
{
// In cases where a page drills into sub-pages then we'll highlight the most recent
// navigation menu item that appears in the BackStack
foreach (var entry in this.AppFrame.BackStack.Reverse())
{
item = (from p in navVM.Items where MapVMToPageType(p.VM) == entry.SourcePageType select p).SingleOrDefault();
if (item != null)
break;
}
}
var container = (ListViewItem)NavMenuList.ContainerFromItem(item);
// While updating the selection state of the item prevent it from taking keyboard focus. If a
// user is invoking the back button via the keyboard causing the selected nav menu item to change
// then focus will remain on the back button.
if (container != null) container.IsTabStop = false;
NavMenuList.SetSelectedItem(container);
if (container != null) container.IsTabStop = true;
}
}
