private async Task OnNavigatingFromAsync(NavigatingCancelEventArgs e, IHandleNavigatingFrom handler)
{
var navigationServiceNavigatingCancelEventArgs = e.ToNavigationServiceNavigatingCancelEventArgs();
await InvokeHandlerOnNavigatingFromAsync(handler, navigationServiceNavigatingCancelEventArgs);
if (!navigationServiceNavigatingCancelEventArgs.Cancel)
{
_alreadyPerformedOnNavigatingFrom = true;
#if WINDOWS_PHONE || WINDOWS_PHONE_81
Dispatcher.BeginInvoke(() =>
{
var frame = this.GetVisualAncestor <Frame>();
switch (e.NavigationMode)
{
case NavigationMode.New:
frame.Navigate(e.Uri);
break;
#else
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var frame = this.Frame;
switch (e.NavigationMode)
{
case NavigationMode.New:
frame.Navigate(e.SourcePageType, e.Parameter, e.NavigationTransitionInfo);
break;
#endif
case NavigationMode.Back:
frame.GoBack();
break;
case NavigationMode.Forward:
frame.GoForward();
break;
}
});
}
}
}
}
/// <summary>
/// Invoked immediately before the page is unloaded and is no longer the current source of a parent frame.
/// </summary>
/// <param name="e">An object that contains the event data.</param>
protected override async void OnNavigatingFrom(NavigatingCancelEventArgs e)
{
base.OnNavigatingFrom(e);
if (_alreadyPerformedOnNavigatingFrom)
{
_alreadyPerformedOnNavigatingFrom = false;
}
else
{
var viewModel = DataContext as IHandleNavigatingFrom;
if (viewModel != null)
{
#if WINDOWS_PHONE || WINDOWS_PHONE_81
if (e.IsCancelable)
{
e.Cancel = true;
}
#else
e.Cancel = true;
#endif
var navigationServiceNavigatingCancelEventArgs = e.ToNavigationServiceNavigatingCancelEventArgs();
await viewModel.OnNavigatingFromAsync(navigationServiceNavigatingCancelEventArgs);
if (navigationServiceNavigatingCancelEventArgs.IsCancelable && !navigationServiceNavigatingCancelEventArgs.Cancel)
{
_alreadyPerformedOnNavigatingFrom = true;
#if WINDOWS_PHONE || WINDOWS_PHONE_81
this.GetVisualAncestor <Frame>().Navigate(e.Uri);
#else
this.GetVisualAncestor <Frame>().Navigate(e.SourcePageType, e.Parameter, e.NavigationTransitionInfo);
#endif
}
}
}
}
private async Task OnNavigatingFromAsync(NavigatingCancelEventArgs e, IHandleNavigatingFrom handler)
{
var navigationServiceNavigatingCancelEventArgs = e.ToNavigationServiceNavigatingCancelEventArgs();
await InvokeHandlerOnNavigatingFromAsync(handler, navigationServiceNavigatingCancelEventArgs);
if (!navigationServiceNavigatingCancelEventArgs.Cancel)
{
_alreadyPerformedOnNavigatingFrom = true;
#if WINDOWS_PHONE || WINDOWS_PHONE_81
Dispatcher.BeginInvoke(() =>
{
var frame = this.GetVisualAncestor<Frame>();
switch (e.NavigationMode)
{
case NavigationMode.New:
frame.Navigate(e.Uri);
break;
#else
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
var frame = this.Frame;
switch (e.NavigationMode)
{
case NavigationMode.New:
frame.Navigate(e.SourcePageType, e.Parameter, e.NavigationTransitionInfo);
break;
#endif
case NavigationMode.Back:
frame.GoBack();
break;
case NavigationMode.Forward:
frame.GoForward();
break;
}
});
}
}
}
}