/// <summary>
/// Occurs when the navigation item has changed.
/// </summary>
/// <param name="oldValue"></param>
/// <param name="newValue"></param>
protected override void OnNavigationItemChanged(NavigationItem oldValue, NavigationItem newValue)
{
base.OnNavigationItemChanged(oldValue, newValue);
this.SelectedItem = null;
UpdateListViewStyle();
}
/// <summary>
/// Invoked when this page is no longer the current page.
/// </summary>
/// <param name="e"></param>
protected override void OnNavigatingFrom(NavigatingCancelEventArgs e)
{
base.OnNavigatingFrom(e);
// make sure the content frame is cleared
if (this.ContentFrame.SourcePageType != null && this.ContentFrame.SourcePageType != typeof(Page)) {
this.ContentFrame.SourcePageType = typeof(Page);
}
this.ContentFrame.BackStack.Clear();
this.ContentFrame.ForwardStack.Clear();
this.lastSelectedItem = null;
}
/// <summary>
/// Occurs when the selected item has changed.
/// </summary>
/// <param name="oldValue"></param>
/// <param name="newValue"></param>
protected override void OnSelectedItemChanged(NavigationItem oldValue, NavigationItem newValue)
{
if (newValue == null || this.lastSelectedItem == newValue) {
return;
}
this.lastSelectedItem = newValue;
if (this.NavigationItem != newValue && ((!newValue.IsLeaf() || this.WindowState == WindowStateNarrow))) {
// navigate to selected item
base.OnSelectedItemChanged(oldValue, newValue);
}
else {
// navigate to content and supply the PageParameter
var pageType = newValue.PageType ?? typeof(Page);
if (pageType != typeof(Page) || this.ContentFrame.SourcePageType != pageType) {
this.ContentFrame.Navigate(pageType, newValue.PageParameter);
}
}
}
/// <summary>
/// Occurs when the navigation item has changed
/// </summary>
/// <param name="oldValue"></param>
/// <param name="newValue"></param>
protected override void OnNavigationItemChanged(NavigationItem oldValue, NavigationItem newValue)
{
base.OnNavigationItemChanged(oldValue, newValue);
if (this.Frame == null || newValue == null) {
this.SelectedItem = null;
return;
}
string layoutStateName = LayoutStateMasterDetail;
if (newValue.IsLeaf()) {
// select navigation item itself
this.SelectedItem = newValue;
layoutStateName = LayoutStateDetail;
}
else if (this.SelectedItem == null) {
// auto-select first child (if not set)
this.SelectedItem = newValue.Items.FirstOrDefault();
}
VisualStateManager.GoToState(this, layoutStateName, false);
}
/// <summary>
/// Occurs when the selected item has changed.
/// </summary>
/// <param name="oldValue"></param>
/// <param name="newValue"></param>
protected virtual void OnSelectedItemChanged(NavigationItem oldValue, NavigationItem newValue)
{
if (newValue != null) {
// navigate to selected item
var pageType = typeof(MasterNavigationPage);
if (IsMasterDetailCandidate(newValue)) {
pageType = typeof(MasterDetailNavigationPage);
}
this.Frame?.Navigate(pageType, newValue);
}
}
/// <summary>
/// Occurs when the navigation item has changed
/// </summary>
/// <param name="oldValue"></param>
/// <param name="newValue"></param>
protected virtual void OnNavigationItemChanged(NavigationItem oldValue, NavigationItem newValue)
{
// update rootitem
this.RootItem = newValue?.GetAncestorsAndSelf().LastOrDefault();
}
/// <summary>
/// Determines whether specified item should be shown in the master-detail view, given the current state
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
protected bool IsMasterDetailCandidate(NavigationItem item)
{
return !item.IsRoot() && (item.IsLeaf() || (!item.HasGrandchildren() && this.WindowState == WindowStateWide));
}
/// <summary>
/// Determines whether the item is a leaf item, meaning it has no children.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
public static bool IsLeaf(this NavigationItem item)
{
return(service.IsLeaf(item));
}
/// <summary>
/// Returns a collection of the siblings after specified item.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
public static IEnumerable <NavigationItem> GetObjectsAfterSelf(this NavigationItem item)
{
return(service.GetObjectsAfterSelf(item));
}
/// <summary>
/// Returns a collection of items that contain the specified item and all descendant items.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
public static IEnumerable <NavigationItem> GetDescendantsAndSelf(this NavigationItem item)
{
return(service.GetDescendantsAndSelf(item));
}
/// <summary>
/// Returns a collection of items that contain specified item, and the ancestors of specified item.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
public static IEnumerable <NavigationItem> GetAncestorsAndSelf(this NavigationItem item)
{
return(service.GetAncestorsAndSelf(item));
}
/// <summary>
/// Determines whether the item has grandchildren.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
public static bool HasGrandchildren(this NavigationItem item)
{
return(service.HasGrandchildren(item));
}
