public void SetElement(VisualElement element)
{
if (element != null && !(element is NavigationPage))
{
throw new ArgumentException("Element must be a Page", nameof(element));
}
NavigationPage oldElement = Element;
Element = (NavigationPage)element;
if (oldElement != null)
{
oldElement.PushRequested -= OnPushRequested;
oldElement.PopRequested -= OnPopRequested;
oldElement.PopToRootRequested -= OnPopToRootRequested;
oldElement.InternalChildren.CollectionChanged -= OnChildrenChanged;
oldElement.PropertyChanged -= OnElementPropertyChanged;
}
if (element != null)
{
if (_container == null)
{
_container = new PageControl();
_container.PointerPressed += OnPointerPressed;
_container.SizeChanged += OnNativeSizeChanged;
_container.BackClicked += OnBackClicked;
Tracker = new BackgroundTracker <PageControl>(Control.BackgroundProperty)
{
Element = (Page)element, Container = _container
};
SetPage(Element.CurrentPage, false, false);
_container.Loaded += OnLoaded;
_container.Unloaded += OnUnloaded;
}
_container.DataContext = Element.CurrentPage;
UpdatePadding();
LookupRelevantParents();
UpdateTitleColor();
UpdateNavigationBarBackground();
UpdateToolbarPlacement();
// Enforce consistency rules on toolbar (show toolbar if top-level page is Navigation Page)
_container.ShouldShowToolbar = _parentMasterDetailPage == null && _parentTabbedPage == null;
if (_parentTabbedPage != null)
{
Element.Appearing += OnElementAppearing;
}
Element.PropertyChanged += OnElementPropertyChanged;
Element.PushRequested += OnPushRequested;
Element.PopRequested += OnPopRequested;
Element.PopToRootRequested += OnPopToRootRequested;
Element.InternalChildren.CollectionChanged += OnChildrenChanged;
if (!string.IsNullOrEmpty(Element.AutomationId))
{
_container.SetValue(Windows.UI.Xaml.Automation.AutomationProperties.AutomationIdProperty, Element.AutomationId);
}
PushExistingNavigationStack();
}
OnElementChanged(new VisualElementChangedEventArgs(oldElement, element));
}