public async Task <INavigationResult> GoForwardAsync()
{
try
{
if (!CanGoForward())
{
return(NavigationResult.Failure($"{nameof(CanGoForward)} is false."));
}
Func <bool> navigate = () =>
{
_frame.GoForward();
return(true);
};
return(await OrchestrateNavigation(
parameters : null,
mode : NavigationMode.Forward,
navigate : navigate));
}
catch (Exception ex)
{
return(NavigationResult.Failure(ex));
}
}
public async Task <INavigationResult> GoBackAsync(INavigationParameters parameters, NavigationTransitionInfo infoOverride)
{
try
{
if (!CanGoBack())
{
return(NavigationResult.Failure($"{nameof(CanGoBack)} is false."));
}
Func <bool> navigate = () =>
{
_frame.GoBack(infoOverride);
return(true);
};
return(await OrchestrateNavigation(
parameters : parameters,
mode : NavigationMode.Back,
navigate : navigate));
}
catch (Exception ex)
{
return(NavigationResult.Failure(ex));
}
}
public async Task <INavigationResult> RefreshAsync()
{
try
{
Func <bool> navigate = () =>
{
_frame.SetNavigationState(_frame.GetNavigationState());
return(!_frame.BackStack.Any());
};
return(await OrchestrateNavigation(
parameters : null,
mode : NavigationMode.Refresh,
navigate : navigate));
}
catch (Exception ex)
{
return(NavigationResult.Failure(ex));
}
}
public async Task <INavigationResult> NavigateAsync(Uri uri, INavigationParameters parameter, NavigationTransitionInfo infoOverride)
{
try
{
var queue = PageNavigationRegistry.ParsePath(uri, parameter);
if (queue.ClearBackStack)
{
_frame.SetNavigationState(new Frame().GetNavigationState());
}
while (queue.Count > 0)
{
var pageNavigationInfo = queue.Dequeue();
Func <bool> navigate = () => _frame.Navigate(
sourcePageType: pageNavigationInfo.Page,
parameter: pageNavigationInfo.Parameters,
infoOverride: infoOverride);
Func <Task <INavigationResult> > orchestrate = async() => await OrchestrateNavigation(
parameters : parameter,
mode : NavigationMode.New,
navigate : navigate);
var result = await orchestrate();
if (!result.Success)
{
return(result);
}
}
return(NavigationResult.Successful());
}
catch (Exception ex)
{
return(NavigationResult.Failure(ex));
}
}
private async Task <INavigationResult> OrchestrateNavigation(INavigationParameters parameters, Prism.Navigation.NavigationMode mode, Func <bool> navigate)
{
// default parameters
parameters = parameters ?? new NavigationParameters();
parameters.SetNavigationMode(mode);
parameters.SetNavigationService(_navigationService);
// hold prev vm
var old_vm = (_frame.Content as Page)?.DataContext;
// CanNavigateAsync
if (old_vm is IConfirmNavigationAsync old_vm_confirma)
{
if (!await old_vm_confirma.CanNavigateAsync(parameters))
{
return(NavigationResult.Failure($"{old_vm_confirma}.CanNavigateAsync returned false."));
}
}
// CanNavigate
if (old_vm is IConfirmNavigation old_vm_confirms)
{
if (!old_vm_confirms.CanNavigate(parameters))
{
return(NavigationResult.Failure($"{old_vm_confirms}.CanNavigate returned false."));
}
}
// navigate
await NavigateInternalAsync(navigate);
// OnNavigatedFrom
if (old_vm is INavigatedAware old_vm_ed)
{
old_vm_ed.OnNavigatedFrom(parameters);
}
// hold new vm
var new_vm = (_frame.Content as Page)?.DataContext;
// OnNavigatingTo
if (new_vm is INavigatingAware new_vm_ing)
{
new_vm_ing.OnNavigatingTo(parameters);
}
// OnNavigatedTo
if (new_vm is INavigatedAware new_vm_ed)
{
new_vm_ed.OnNavigatedTo(parameters);
}
// finally
return(NavigationResult.Successful());
}