public IObservable<bool> GetActivationForView(IActivatable view)
{
var control = view as Control;
if (control == null) {
// Show a friendly warning in the log that this view will never be activated
this.Log().Warn("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.Empty<bool>();
}
// Create an observable stream of booleans
// true representing the control is active, false representing the control is not active
// by using DistinctUntilChanged, a control can either be active or not active
// This should also fix #610 for winforms
var controlVisible = Observable.FromEventPattern(control, "VisibleChanged").Select(_ => control.Visible);
var handleDestroyed = Observable.FromEventPattern(control, "HandleDestroyed").Select(_ => false);
var handleCreated = Observable.FromEventPattern(control, "HandleCreated").Select(_ => true);
var controlActive = Observable.Merge(controlVisible, handleDestroyed, handleCreated)
.DistinctUntilChanged();
var form = view as Form;
if (form != null) {
var formActive = Observable.FromEventPattern(form, "Closed").Select(_ => false);
return controlActive.Merge(formActive).DistinctUntilChanged();
}
return controlActive;
}
/// <summary>
/// WhenActivated allows you to register a Func to be called when a
/// View is Activated.
/// </summary>
/// <param name="block">The method to be called when the corresponding
/// View is activated. It returns a list of Disposables that will be
/// cleaned up when the View is deactivated.</param>
/// <returns>A Disposable that deactivates this registration.</returns>
public static IDisposable WhenActivated(this IActivatable This, Func <IEnumerable <IDisposable> > block)
{
var activationFetcher = activationFetcherCache.Get(This.GetType());
if (activationFetcher == null)
{
var msg = "Don't know how to detect when {0} is activated/deactivated, you may need to implement IActivationForViewFetcher";
throw new ArgumentException(String.Format(msg, This.GetType().FullName));
}
var activationEvents = activationFetcher.GetActivationForView(This);
var vmDisposable = Disposable.Empty;
if (This is IViewFor)
{
vmDisposable = handleViewModelActivation(This as IViewFor, activationEvents);
}
var viewDisposable = handleViewActivation(block, activationEvents);
return(new CompositeDisposable(vmDisposable, viewDisposable));
}
/// <summary>
/// WhenActivated allows you to register a Func to be called when a
/// View is Activated.
/// </summary>
/// <param name="this">Object that supports activation.</param>
/// <param name="block">
/// The method to be called when the corresponding
/// View is activated. It returns a list of Disposables that will be
/// cleaned up when the View is deactivated.
/// </param>
/// <param name="view">
/// The IActivatable will ordinarily also host the View
/// Model, but in the event it is not, a class implementing <see cref="IViewFor" />
/// can be supplied here.
/// </param>
/// <returns>A Disposable that deactivates this registration.</returns>
public static IDisposable WhenActivated(this IActivatable @this, Func <IEnumerable <IDisposable> > block, IViewFor view)
{
var activationFetcher = activationFetcherCache.Get(@this.GetType());
if (activationFetcher == null)
{
const string msg = "Don't know how to detect when {0} is activated/deactivated, you may need to implement IActivationForViewFetcher";
throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, msg, @this.GetType().FullName));
}
var activationEvents = activationFetcher.GetActivationForView(@this);
var vmDisposable = Disposable.Empty;
if ((view ?? @this) is IViewFor v)
{
vmDisposable = HandleViewModelActivation(v, activationEvents);
}
var viewDisposable = HandleViewActivation(block, activationEvents);
return(new CompositeDisposable(vmDisposable, viewDisposable));
}
/// <inheritdoc/>
public IObservable <bool> GetActivationForView(IActivatable 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.FromEventPattern(control, "HandleDestroyed").Select(_ => false);
var handleCreated = Observable.FromEventPattern(control, "HandleCreated").Select(_ => true);
var visibleChanged = Observable.FromEventPattern(control, "VisibleChanged").Select(_ => control.Visible);
var controlActivation = Observable.Merge(handleDestroyed, handleCreated, visibleChanged)
.DistinctUntilChanged();
if (view is Form form)
{
var formClosed = Observable.FromEventPattern(form, "FormClosed").Select(_ => false);
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);
}
public IObservable <bool> GetActivationForView(IActivatable view)
{
var control = view as Control;
if (control == null)
{
// Show a friendly warning in the log that this view will never be activated
this.Log().Warn("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);
}
// Create an observable stream of booleans
// true representing the control is active, false representing the control is not active
// by using DistinctUntilChanged, a control can either be active or not active
// This should also fix #610 for winforms
var controlVisible = Observable.FromEventPattern(control, "VisibleChanged").Select(_ => control.Visible);
var handleDestroyed = Observable.FromEventPattern(control, "HandleDestroyed").Select(_ => false);
var handleCreated = Observable.FromEventPattern(control, "HandleCreated").Select(_ => true);
var controlActive = Observable.Merge(controlVisible, handleDestroyed, handleCreated)
.DistinctUntilChanged();
var form = view as Form;
if (form != null)
{
var formActive = Observable.FromEventPattern(form, "Closed").Select(_ => false);
return(controlActive.Merge(formActive).DistinctUntilChanged());
}
return(controlActive);
}