public static async Task DeactivateViewModelAsync(object target, NavigationType navigationType, DeactivationParameters parameters)
{
var deactivate = target as IDeactivate;
if (deactivate != null)
{
await deactivate.DeactivateAsync(navigationType, parameters);
}
}
public static async Task<bool> CanDeactivateViewModelAsync(object target, NavigationType navigationType, DeactivationParameters parameters)
{
var query = target as IDeactivateQuery;
if (query != null)
{
if (!await query.CanDeactivateAsync(navigationType, parameters))
{
return false;
}
}
return true;
}
private async Task <bool> NavigateAndActivateAsync(Type viewModelType, object activationData)
{
var parameters = new DeactivationParameters(viewModelType, activationData);
if (!await this.DeactivatePreviousViewModelsAsync(NavigationType.Forward, viewModelType, parameters))
{
return(false);
}
var viewType = await this.viewLocator.GetViewTypeAsync(viewModelType);
var viewModel = await this.viewModelLocator.GetInstanceAsync(viewModelType);
var currentViewModel = this.ActiveViewModelType;
var currentView = currentViewModel != null ? await this.viewLocator.GetViewTypeAsync(currentViewModel) : null;
// activating the ViewModel instance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Forward);
}
else
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Forward, parameters.DeactivationData);
}
// navigate to target View
this.platformNavigator.Navigate(viewType);
// push state
await this.statePersistor.PushStateAsync(viewModel, parameters.DeactivationData, this.platformNavigator.GetNavigationState());
this.ActiveViewModelType = viewModelType;
// raise navigated event
this.Navigated?.Invoke(this, new NavigationEventArgs(NavigationType.Forward, currentViewModel, currentView, viewModelType, viewType, parameters.DeactivationData));
// activate the ViewModel instance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Forward);
}
else
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Forward, parameters.DeactivationData);
}
return(true);
}
private async Task <bool> GoBackAndActivateAsync(object deactivationData)
{
var nextState = (await this.statePersistor.GetAllStatesAsync()).Select(s => s).Reverse().Skip(1).First();
var parameters = new DeactivationParameters(nextState.ViewModelType, deactivationData);
if (!await this.DeactivatePreviousViewModelsAsync(NavigationType.Backward, null, parameters))
{
return(false);
}
var viewModel = await this.viewModelLocator.GetInstanceAsync(nextState.ViewModelType);
var viewType = await this.viewLocator.GetViewTypeAsync(nextState.ViewModelType);
var lastState = await this.statePersistor.PopStateAsync();
var lastViewType = await this.viewLocator.GetViewTypeAsync(lastState.ViewModelType);
// activating the ViewModelInstance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Backward);
}
else
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Backward, parameters.DeactivationData);
}
// go back to previous View
this.platformNavigator.GoBack(lastState.ViewModelType, lastViewType);
this.ActiveViewModelType = nextState.ViewModelType;
// raise navigated event
this.Navigated?.Invoke(this, new NavigationEventArgs(NavigationType.Backward, lastState.ViewModelType, lastViewType, nextState.ViewModelType, viewType, parameters.DeactivationData));
// activate the ViewModel instance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Backward);
}
else
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Backward, parameters.DeactivationData);
}
return(true);
}
private async Task<bool> DeactivatePreviousViewModelsAsync(NavigationType navigationType, Type newViewModelTypeOverride, DeactivationParameters parameters, bool rootNavigation)
{
IEnumerable<State> stack = await this.statePersistor.GetAllStatesAsync();
bool navigationTypeOverriden = false;
if (stack.Any())
{
var viewModelsToDeactivate = stack
.SkipWhile(i => !rootNavigation && i.ViewModelType != newViewModelTypeOverride)
.Select(i => i.ViewModelType)
.Reverse()
.ToList();
if (viewModelsToDeactivate.Count == 0)
{
viewModelsToDeactivate.Add(stack.Last().ViewModelType);
}
else
{
// target ViewModel already exists on the stack, meaning from the perspective of the existing ViewModels, the navigation is going back
navigationType = NavigationType.Backward;
navigationTypeOverriden = true;
}
// first check if all can deactivate
foreach (var viewModelType in viewModelsToDeactivate)
{
var viewModel = await this.viewModelLocator.GetInstanceAsync(viewModelType);
if (!await ViewModelActivator.CanDeactivateViewModelAsync(viewModel, navigationType, parameters))
{
return false;
}
}
// if all can deactivate, do so
foreach (var viewModelType in viewModelsToDeactivate)
{
var viewModel = await this.viewModelLocator.GetInstanceAsync(viewModelType);
await ViewModelActivator.DeactivateViewModelAsync(viewModel, navigationType, parameters);
}
if (navigationTypeOverriden)
{
foreach (var viewModelType in viewModelsToDeactivate)
{
// pop the extra ViewModels from the persistence stack
await this.statePersistor.PopStateAsync();
// when navigating forward to existing ViewModel (large screen with the first View visible) we must manually unhook existing ViewTypes, since they are no longer active
var viewType = await this.viewLocator.GetViewTypeAsync(viewModelType);
//this.platformNavigator.UnhookType(viewType);
this.platformNavigator.GoBack(viewModelType, viewType);
}
}
}
return true;
}
private async Task<bool> GoBackAndActivateAsync(object deactivationData)
{
var nextState = (await this.statePersistor.GetAllStatesAsync()).Select(s => s).Reverse().Skip(1).First();
var parameters = new DeactivationParameters(nextState.ViewModelType, deactivationData);
if (! await this.DeactivatePreviousViewModelsAsync(NavigationType.Backward, null, parameters, false))
{
return false;
}
var viewModel = await this.viewModelLocator.GetInstanceAsync(nextState.ViewModelType);
var viewType = await this.viewLocator.GetViewTypeAsync(nextState.ViewModelType);
var lastState = await this.statePersistor.PopStateAsync();
var lastViewType = await this.viewLocator.GetViewTypeAsync(lastState.ViewModelType);
// activating the ViewModelInstance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Backward);
}
else
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Backward, parameters.DeactivationData);
}
// go back to previous View
this.platformNavigator.GoBack(lastState.ViewModelType, lastViewType);
this.ActiveViewModelType = nextState.ViewModelType;
// raise navigated event
this.Navigated?.Invoke(this, new NavigationEventArgs(NavigationType.Backward, lastState.ViewModelType, lastViewType, nextState.ViewModelType, viewType, parameters.DeactivationData));
// activate the ViewModel instance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Backward);
}
else
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Backward, parameters.DeactivationData);
}
return true;
}
private async Task<bool> NavigateAndActivateAsync(Type viewModelType, object activationData, bool isRoot)
{
var parameters = new DeactivationParameters(viewModelType, activationData);
if (!await this.DeactivatePreviousViewModelsAsync(NavigationType.Forward, viewModelType, parameters, isRoot))
{
return false;
}
var viewType = await this.viewLocator.GetViewTypeAsync(viewModelType);
var viewModel = await this.viewModelLocator.GetInstanceAsync(viewModelType);
var currentViewModel = this.ActiveViewModelType;
var currentView = currentViewModel != null ? await this.viewLocator.GetViewTypeAsync(currentViewModel) : null;
// activating the ViewModel instance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Forward);
}
else
{
ViewModelActivator.ActivatingViewModel(viewModel, NavigationType.Forward, parameters.DeactivationData);
}
// navigate to target View
this.platformNavigator.Navigate(viewType);
// push state
await this.statePersistor.PushStateAsync(viewModel, parameters.DeactivationData, this.platformNavigator.GetNavigationState());
this.ActiveViewModelType = viewModelType;
// raise navigated event
this.Navigated?.Invoke(this, new NavigationEventArgs(NavigationType.Forward, currentViewModel, currentView, viewModelType, viewType, parameters.DeactivationData));
// activate the ViewModel instance
if (parameters.DeactivationData == null)
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Forward);
}
else
{
ViewModelActivator.ActivateViewModel(viewModel, NavigationType.Forward, parameters.DeactivationData);
}
return true;
}
private async Task <bool> DeactivatePreviousViewModelsAsync(NavigationType navigationType, Type newViewModelTypeOverride, DeactivationParameters parameters)
{
IEnumerable <State> stack = await this.statePersistor.GetAllStatesAsync();
bool navigationTypeOverriden = false;
if (stack.Any())
{
var viewModelsToDeactivate = stack
.SkipWhile(i => i.ViewModelType != newViewModelTypeOverride)
.Select(i => i.ViewModelType)
.Reverse()
.ToList();
if (viewModelsToDeactivate.Count == 0)
{
viewModelsToDeactivate.Add(stack.Last().ViewModelType);
}
else
{
// target ViewModel already exists on the stack, meaning from the perspective of the existing ViewModels, the navigation is going back
navigationType = NavigationType.Backward;
navigationTypeOverriden = true;
}
// first check if all can deactivate
foreach (var viewModelType in viewModelsToDeactivate)
{
var viewModel = await this.viewModelLocator.GetInstanceAsync(viewModelType);
if (!await ViewModelActivator.CanDeactivateViewModelAsync(viewModel, navigationType, parameters))
{
return(false);
}
}
// if all can deactivate, do so
foreach (var viewModelType in viewModelsToDeactivate)
{
var viewModel = await this.viewModelLocator.GetInstanceAsync(viewModelType);
await ViewModelActivator.DeactivateViewModelAsync(viewModel, navigationType, parameters);
}
if (navigationTypeOverriden)
{
foreach (var viewModelType in viewModelsToDeactivate)
{
// pop the extra ViewModels from the persistence stack
await this.statePersistor.PopStateAsync();
// when navigating forward to existing ViewModel (large screen with the first View visible) we must manually unhook existing ViewTypes, since they are no longer active
var viewType = await this.viewLocator.GetViewTypeAsync(viewModelType);
//this.platformNavigator.UnhookType(viewType);
this.platformNavigator.GoBack(viewModelType, viewType);
}
}
}
return(true);
}
public async Task DeactivateAsync(NavigationType navigationType, DeactivationParameters parameters)
{
parameters.OverrideDefaultResult(navigationType, false);
}
