/// <inheritdoc/>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
if (view is not FrameworkElement fe)
{
return(Observable <bool> .Empty);
}
var viewLoaded = Observable.FromEvent <TypedEventHandler <FrameworkElement, object>, bool>(
eventHandler =>
{
void Handler(FrameworkElement sender, object e) => eventHandler(true);
return(Handler);
},
x => fe.Loading += x,
x => fe.Loading -= x);
var viewUnloaded = Observable.FromEvent <RoutedEventHandler, bool>(
eventHandler =>
{
void Handler(object sender, RoutedEventArgs e) => eventHandler(false);
return(Handler);
},
x => fe.Unloaded += x,
x => fe.Unloaded -= x);
return(viewLoaded
.Merge(viewUnloaded)
.Select(b => b ? fe.WhenAnyValue(x => x.IsHitTestVisible).SkipWhile(x => !x) : Observables.False)
.Switch()
.DistinctUntilChanged());
}
/// <inheritdoc/>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
if (view is not FrameworkElement fe)
{
return(Observable <bool> .Empty);
}
#pragma warning disable SA1114 // Parameter list after.
#if NETSTANDARD
var viewLoaded = Observable.FromEvent <RoutedEventHandler, bool>(
#else
var viewLoaded = Observable.FromEvent <TypedEventHandler <DependencyObject, object>, bool>(
#endif
eventHandler => (_, _) => eventHandler(true),
x => fe.Loading += x,
x => fe.Loading -= x);
var viewUnloaded = Observable.FromEvent <RoutedEventHandler, bool>(
handler =>
{
void EventHandler(object sender, RoutedEventArgs e) => handler(false);
return(EventHandler);
},
x => fe.Unloaded += x,
x => fe.Unloaded -= x);
return(viewLoaded
.Merge(viewUnloaded)
.Select(b => b ? fe.WhenAnyValue(x => x.IsHitTestVisible).SkipWhile(x => !x) : Observables.False)
.Switch()
.DistinctUntilChanged());
}
/// <summary>
/// Get an observable defining whether the view is active.
/// </summary>
/// <param name="view">The view to observe.</param>
/// <returns>An observable tracking whether the view is active.</returns>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
if (view is not ICanActivate canActivate)
{
return(Observable.Return(false));
}
return(canActivate.Activated.Select(_ => true).Merge(canActivate.Deactivated.Select(_ => false)));
}
public IObservable <bool> GetActivationForView(IActivatableView view)
{
if (!(view is ActivatingView av))
{
throw new ArgumentNullException(nameof(view));
}
return(av.Loaded.Select(_ => true).Merge(av.Unloaded.Select(_ => false)));
}
/// <inheritdoc/>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
// Startup: Control.HandleCreated > Control.BindingContextChanged > Form.Load > Control.VisibleChanged > Form.Activated > Form.Shown
// Shutdown: Form.Closing > Form.FormClosing > Form.Closed > Form.FormClosed > Form.Deactivate
// https://docs.microsoft.com/en-us/dotnet/framework/winforms/order-of-events-in-windows-forms
if (view is Control control)
{
if (GetCachedIsDesignMode(control))
{
return(Observable <bool> .Empty);
}
var handleDestroyed = Observable.FromEvent <EventHandler, bool>(
eventHandler => (sender, e) => eventHandler(false),
h => control.HandleDestroyed += h,
h => control.HandleDestroyed -= h);
var handleCreated = Observable.FromEvent <EventHandler, bool>(
eventHandler => (sender, e) => eventHandler(true),
h => control.HandleCreated += h,
h => control.HandleCreated -= h);
var visibleChanged = Observable.FromEvent <EventHandler, bool>(
eventHandler => (sender, e) => eventHandler(control.Visible),
h => control.VisibleChanged += h,
h => control.VisibleChanged -= h);
var controlActivation = Observable.Merge(handleDestroyed, handleCreated, visibleChanged)
.DistinctUntilChanged();
if (view is Form form)
{
var formClosed = Observable.FromEvent <FormClosedEventHandler, bool>(
eventHandler =>
{
void Handler(object sender, FormClosedEventArgs e) => eventHandler(control.Visible);
return(Handler);
},
h => form.FormClosed += h,
h => form.FormClosed -= h);
controlActivation = controlActivation.Merge(formClosed)
.DistinctUntilChanged();
}
return(controlActivation);
}
// Show a friendly warning in the log that this view will never be activated
this.Log().Warn(
CultureInfo.InvariantCulture,
"Expected a view of type System.Windows.Forms.Control but it is {0}.\r\nYou need to implement your own IActivationForViewFetcher for {0}.",
view?.GetType());
return(Observable <bool> .Empty);
}
/// <summary>
/// Get an observable defining whether the view is active.
/// </summary>
/// <param name="view">The view to observe.</param>
/// <returns>An observable tracking whether the view is active.</returns>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
var canActivate = view as ICanActivate;
if (canActivate == null)
{
return(Observable.Empty(false));
}
return(canActivate.Activated.Select(_ => true).Merge(canActivate.Deactivated.Select(_ => false)));
}
/// <inheritdoc/>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
var activation =
GetActivationFor(view as ICanActivate) ??
GetActivationFor(view as Page) ??
GetActivationFor(view as View) ??
GetActivationFor(view as Cell) ??
Observable <bool> .Never;
return(activation.DistinctUntilChanged());
}
/// <summary>
/// Returns activation observable for activatable Avalonia view.
/// </summary>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
if (!(view is IVisual visual))
{
return(Observable.Return(false));
}
if (view is WindowBase window)
{
return(GetActivationForWindowBase(window));
}
return(GetActivationForVisual(visual));
}
/// <summary>
/// Returns activation observable for activatable Avalonia view.
/// </summary>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
if (!(view is IVisual visual))
{
return(Observable.Return(false));
}
if (view is Control control)
{
return(GetActivationForControl(control));
}
return(GetActivationForVisual(visual));
}
/// <inheritdoc/>
public IObservable <bool> GetActivationForView(IActivatableView view)
{
if (!(view is FrameworkElement fe))
{
return(Observable <bool> .Empty);
}
var viewLoaded = Observable.FromEvent <RoutedEventHandler, bool>(
eventHandler =>
{
void Handler(object sender, RoutedEventArgs e) => eventHandler(true);
return(Handler);
},
x => fe.Loaded += x,
x => fe.Loaded -= x);
var hitTestVisible = Observable.FromEvent <DependencyPropertyChangedEventHandler, bool>(
eventHandler =>
{
void Handler(object sender, DependencyPropertyChangedEventArgs e) => eventHandler((bool)e.NewValue);
return(Handler);
},
x => fe.IsHitTestVisibleChanged += x,
x => fe.IsHitTestVisibleChanged -= x);
var viewUnloaded = Observable.FromEvent <RoutedEventHandler, bool>(
eventHandler =>
{
void Handler(object sender, RoutedEventArgs e) => eventHandler(false);
return(Handler);
},
x => fe.Unloaded += x,
x => fe.Unloaded -= x);
var windowActivation = GetActivationForWindow(view);
var dispatcherActivation = GetActivationForDispatcher(fe);
return(viewLoaded
.Merge(viewUnloaded)
.Merge(hitTestVisible)
.Merge(windowActivation)
.Merge(dispatcherActivation)
.DistinctUntilChanged());
}
private static IObservable <bool> GetActivationForWindow(IActivatableView view)
{
if (view is not Window window)
{
return(Observable <bool> .Empty);
}
var viewClosed = Observable.FromEvent <EventHandler, bool>(
eventHandler =>
{
void Handler(object?sender, EventArgs e) => eventHandler(false);
return(Handler);
},
x => window.Closed += x,
x => window.Closed -= x);
return(viewClosed);
}
public IObservable <bool> GetActivationForView(IActivatableView view)
{
var av = view as ActivatingView;
return(av.Loaded.Select(_ => true).Merge(av.Unloaded.Select(_ => false)));
}