/// <summary>
/// Asynchronously navigates to an instance of the provided ViewModel type. The navigation will be cancelled if
/// the current active ViewModel cannot be closed or the target type is not authorized.
/// </summary>
/// <param name="prepare"> An action to initialize the target ViewModel before it is activated. </param>
/// <typeparam name="T"> The target ViewModel type. </typeparam>
/// <returns> A <see cref="Task" /> to await completion. </returns>
public Task NavigateToAsync <T>(Action <T> prepare)
{
if (prepare == null)
{
throw new ArgumentNullException("prepare");
}
return(NavigateToAsync <T>(viewModel =>
{
prepare(viewModel);
return TaskFns.FromResult(true);
}));
}
/// <summary>
/// Determines if the target ViewModel type is authorized.
/// </summary>
/// <param name="viewModelType"> The target ViewModel type. </param>
/// <returns> Return true if the target type is authorized. </returns>
private Task <bool> AuthorizeTargetAsync(Type viewModelType)
{
if (viewModelType == null)
{
throw new ArgumentNullException("viewModelType");
}
if (_configuration.TargetGuard != null)
{
return(_configuration.TargetGuard(viewModelType));
}
return(TaskFns.FromResult(true));
}
/// <summary>
/// Determines if the target ViewModel type is authorized.
/// </summary>
/// <param name="viewModelType"> The target ViewModel type. </param>
/// <param name="contractName">The target ViewModel contract name.</param>
/// <returns> Return true if the target type is authorized. </returns>
private Task <bool> AuthorizeTargetAsync(Type viewModelType, string contractName)
{
if (viewModelType == null && string.IsNullOrEmpty(contractName))
{
throw new ArgumentNullException();
}
if (_configuration.TargetGuard != null)
{
return(_configuration.TargetGuard(viewModelType, contractName));
}
return(TaskFns.FromResult(true));
}
/// <summary>
/// Asynchronously navigates to an instance of the provided ViewModel type. The navigation will be cancelled if
/// the current active ViewModel cannot be closed or the target type is not authorized.
/// </summary>
/// <param name="viewModelType"> The target ViewModel type. </param>
/// <param name="prepare"> An action to initialize the target ViewModel before it is activated. </param>
/// <returns> A <see cref="Task" /> to await completion. </returns>
public Task NavigateToAsync(Type viewModelType, Action <object> prepare)
{
if (viewModelType == null)
{
throw new ArgumentNullException("viewModelType");
}
if (prepare == null)
{
throw new ArgumentNullException("prepare");
}
return(NavigateToAsync(viewModelType, viewModel =>
{
prepare(viewModel);
return TaskFns.FromResult(true);
}));
}
/// <summary>
/// Asynchronously navigates to a ViewModel instance that matches the specified name and type.
/// The navigation will be cancelled if the current active ViewModel cannot be closed or the target type is not authorized.
/// </summary>
/// <param name="viewModelType"> The type to match. </param>
/// <param name="contractName"> The name to match. </param>
/// <param name="prepare"> An action to initialize the target ViewModel before it is activated. </param>
/// <returns> A <see cref="Task" /> to await completion. </returns>
/// <remarks>
/// Not available in Windows 8 Store apps.
/// </remarks>
public Task NavigateToAsync(Type viewModelType, string contractName, Action <object> prepare)
{
if (viewModelType == null && string.IsNullOrEmpty(contractName))
{
throw new ArgumentNullException();
}
if (prepare == null)
{
throw new ArgumentNullException("prepare");
}
return(NavigateToAsync(viewModelType, contractName, viewModel =>
{
prepare(viewModel);
return TaskFns.FromResult(true);
}));
}
/// <summary>
/// Determines if the active ViewModel can be closed.
/// </summary>
/// <returns> Returns true if the active ViewModel can be closed. </returns>
private Task <bool> CanCloseAsync()
{
if (ActiveViewModel == null)
{
return(TaskFns.FromResult(true));
}
if (_configuration.ActiveItemGuard != null)
{
return(_configuration.ActiveItemGuard(ActiveViewModel));
}
var closeGuard = ActiveViewModel as IGuardClose;
if (closeGuard != null)
{
return(TaskFns.FromCallbackAction <bool>(closeGuard.CanClose));
}
return(TaskFns.FromResult(true));
}
/// <summary>
/// Provides an opportunity to perform asynchronous configuration at runtime.
/// </summary>
protected virtual Task StartRuntimeAsync()
{
return(TaskFns.FromResult(true));
}