public virtual bool Navigate(NavigatingCancelEventArgsBase args, IDataContext dataContext)
{
Should.NotBeNull(args, "args");
if (!args.IsCancelable)
return false;
var eventArgs = ((NavigatingCancelEventArgs)args);
if (eventArgs.NavigationMode != NavigationMode.Back && eventArgs.Mapping != null)
return Navigate(eventArgs.Mapping, eventArgs.Parameter, dataContext);
var activity = PlatformExtensions.CurrentActivity;
if (activity == null)
return false;
GoBack();
return activity.IsFinishing;
}
bool INavigationService.Navigate(NavigatingCancelEventArgsBase args, IDataContext dataContext)
{
if (NavigateArgs == null)
return false;
return NavigateArgs(args);
}
public virtual bool Navigate(NavigatingCancelEventArgsBase args, IDataContext dataContext)
{
Should.NotBeNull(args, nameof(args));
if (!args.IsCancelable)
return false;
var eventArgs = (NavigatingCancelEventArgs)args;
if (eventArgs.NavigationMode == NavigationMode.Back)
return GoBackInternal();
// ReSharper disable once AssignNullToNotNullAttribute
return Navigate(eventArgs.Mapping, eventArgs.Parameter, dataContext);
}
private bool NavigateInternal(NavigatingCancelEventArgsBase args)
{
if (!args.IsCancelable)
return false;
NavigatingCancelEventArgs originalArgs = ((NavigatingCancelEventArgsWrapper)args).Args;
if (originalArgs.NavigationMode == NavigationMode.Back)
{
_frame.GoBack();
return true;
}
return _frame.Navigate(originalArgs.Uri);
}
public virtual void OnNavigating(NavigatingCancelEventArgsBase e)
{
EventHandler<INavigationService, NavigatingCancelEventArgsBase> handler = Navigating;
if (handler != null) handler(this, e);
}
public virtual bool Navigate(NavigatingCancelEventArgsBase args, IDataContext context)
{
Should.NotBeNull(args, nameof(args));
if (!args.IsCancelable)
return false;
var eventArgs = (NavigatingCancelEventArgs)args;
//Back button pressed.
if (eventArgs.IsBackButtonNavigation && XamarinFormsExtensions.SendBackButtonPressed != null)
{
var sendBackButton = XamarinFormsExtensions.SendBackButtonPressed(CurrentContent as Page);
if (sendBackButton != null)
{
RaiseNavigated(null, null, NavigationMode.Back);
sendBackButton();
return true;
}
}
if (eventArgs.NavigationMode == NavigationMode.Back)
{
GoBack();
return true;
}
// ReSharper disable once AssignNullToNotNullAttribute
return Navigate(eventArgs.Mapping, eventArgs.Parameter, context);
}
private bool NavigateInternal(NavigatingCancelEventArgsBase args)
{
if (!args.IsCancelable)
return false;
var wrapper = (NavigatingCancelEventArgsWrapper)args;
if (wrapper.Args.NavigationMode == NavigationMode.Back)
{
_frame.GoBack();
return true;
}
return Navigate(wrapper.Args.SourcePageType, wrapper.Parameter, null);
}
protected virtual INavigationContext CreateContextNavigateFrom(IViewModel viewModelFrom, NavigatingCancelEventArgsBase args)
{
string idOperation;
GetViewModelTypeFromParameter(NavigationService.GetParameterFromArgs(args), out idOperation);
return new NavigationContext(NavigationType.Page, args.NavigationMode, viewModelFrom,
idOperation == _currentOperationId ? _navigationTargetVm : null, this)
{
{NavigatingCancelArgsConstant, args},
{OperationIdConstant, idOperation}
};
}
private void Renavigate(IViewModel currentViewModel, [NotNull] INavigationContext context, NavigatingCancelEventArgsBase args)
{
if (CurrentContent != null)
TryCacheViewModel(context, CurrentContent, currentViewModel);
if (_navigatingCancelArgs == null)
{
if (NavigationService.Navigate(args, _lastContext))
ClearCacheIfNeed(_lastContext ?? DataContext.Empty, _navigationTargetVm);
else
CancelCurrentNavigation(context);
}
else
_navigatingCancelArgs.Cancel = false;
}
public bool Navigate(NavigatingCancelEventArgsBase args, IDataContext dataContext)
{
Should.NotBeNull(args, "args");
if (args is BackButtonNavigatingEventArgs)
{
var application = Application.Current;
if (application == null)
return false;
RaiseNavigated(BackButtonNavigationEventArgs.Instance);
application.Exit();
return true;
}
var result = NavigateInternal(args);
if (result)
ClearNavigationStackIfNeed(dataContext);
return result;
}
/// <summary>
/// Subscriber to the Navigating event.
/// </summary>
protected virtual void NavigationServiceOnNavigating(object sender, NavigatingCancelEventArgsBase args)
{
try
{
_navigatingCancelArgs = args;
OnNavigating(args);
}
finally
{
_navigatingCancelArgs = null;
}
}
/// <summary>
/// Navigates using cancel event args.
/// </summary>
public bool Navigate(NavigatingCancelEventArgsBase args, IDataContext context)
{
Should.NotBeNull(args, "args");
if (!args.IsCancelable)
return false;
if (args.NavigationMode == NavigationMode.Back)
{
GoBack();
return true;
}
var eventArgs = ((NavigatingCancelEventArgs)args);
// ReSharper disable once AssignNullToNotNullAttribute
return Navigate(eventArgs.Mapping, eventArgs.Parameter, context);
}
public bool Navigate(NavigatingCancelEventArgsBase args, IDataContext dataContext)
{
Should.NotBeNull(args, nameof(args));
#if WINDOWS_PHONE
if (args is BackButtonNavigatingEventArgs)
{
var application = Application.Current;
if (application == null)
return false;
RaiseNavigated(BackButtonNavigationEventArgs.Instance);
application.Terminate();
return true;
}
#endif
bool result = NavigateInternal(args);
if (result)
ClearNavigationStackIfNeed(dataContext);
return result;
}
/// <summary>
/// Navigates using cancel event args.
/// </summary>
public bool Navigate(NavigatingCancelEventArgsBase args, IDataContext context)
{
Should.NotBeNull(args, "args");
if (!args.IsCancelable)
return false;
var eventArgs = ((NavigatingCancelEventArgs)args);
if (eventArgs.IsBackButtonNavigation && SendBackButtonPressed != null)
return SendBackButtonPressed(CurrentContent as Page);
if (eventArgs.NavigationMode == NavigationMode.Back)
{
GoBack();
return true;
}
// ReSharper disable once AssignNullToNotNullAttribute
return Navigate(eventArgs.Mapping, eventArgs.Parameter, context);
}
/// <summary>
/// Navigates using cancel event args.
/// </summary>
public bool Navigate(NavigatingCancelEventArgsBase args, IDataContext dataContext)
{
Should.NotBeNull(args, "args");
var result = NavigateInternal(args);
if (result)
ClearNavigationStackIfNeed(dataContext);
return result;
}
private void OnNavigating(NavigatingCancelEventArgsBase args)
{
if (_ignoreNavigating)
return;
var currentViewModel = CurrentViewModel;
if (currentViewModel == null)
return;
try
{
_closingViewModel = currentViewModel;
args.Cancel = true;
var context = CreateContextNavigateFrom(currentViewModel, args);
var navigateTask = (_closedFromViewModel || !args.IsCancelable)
? Empty.TrueTask
: OnNavigatingFrom(currentViewModel, context);
var t = navigateTask.TryExecuteSynchronously(task =>
{
if (!task.IsCanceled && task.IsFaulted)
{
_closingViewModel = null;
var callback = _currentCallback;
if (callback != null)
{
callback.Invoke(OperationResult.CreateErrorResult<bool?>(OperationType.PageNavigation,
currentViewModel, task.Exception, context));
_currentCallback = null;
}
return;
}
if (task.IsCanceled || !task.Result)
{
_closingViewModel = null;
CancelCurrentNavigation(context);
return;
}
ThreadManager.InvokeOnUiThreadAsync(() =>
{
try
{
_ignoreNavigating = true;
Renavigate(currentViewModel, context, args);
}
finally
{
_closingViewModel = null;
_ignoreNavigating = false;
}
});
});
t.WithTaskExceptionHandler(this);
}
catch (Exception)
{
_closingViewModel = null;
throw;
}
}
private bool NavigateInternal(NavigatingCancelEventArgsBase args)
{
if (!args.IsCancelable)
return false;
NavigatingCancelEventArgs originalArgs = ((NavigatingCancelEventArgsWrapper)args).Args;
if (originalArgs.NavigationMode == NavigationMode.Back)
{
_frame.GoBack();
return true;
}
if (_useUrlNavigation)
{
if (originalArgs.ExtraData == null)
return _frame.Navigate(originalArgs.Uri);
return _frame.Navigate(originalArgs.Uri, originalArgs.ExtraData);
}
if (originalArgs.ExtraData == null)
return _frame.Navigate(originalArgs.Content);
return _frame.Navigate(originalArgs.Content, originalArgs.ExtraData);
}
protected virtual INavigationContext CreateContextNavigateFrom(IViewModel viewModelFrom, NavigatingCancelEventArgsBase args)
{
string idOperation;
GetViewModelTypeFromParameter(NavigationService.GetParameterFromArgs(args), out idOperation);
var viewModelTo = idOperation == _currentOperationId ? _navigationTargetVm : null;
if (viewModelTo == null && viewModelFrom != null && args.NavigationMode == NavigationMode.Back)
viewModelTo = viewModelFrom.GetParentViewModel();
return new NavigationContext(NavigationType.Page, args.NavigationMode, viewModelFrom, viewModelTo, this)
{
{NavigationProviderConstants.NavigatingCancelArgs, args},
{NavigationProviderConstants.OperationId, idOperation}
};
}
