Revit external command with progress bar and 'Cancel' button - api

Question

I am developing a new external command for Revit. it needs a progress bar + a button to cancel its execution in any moment.
In order to get it, I haver implemented a external event.
Implementing an external event handler with de code to be executed by the command.
public class GestorDeEventoExterno : IExternalEventHandler
{
public bool CancellationRequested { get; set; }
private VentanaDeProgreso progressAndcancelWindow;
private EventWaitHandle eventWait;
public void Execute(UIApplication aplicacionDeLaIU)
{
using (this.eventWait = new AutoResetEvent(false))
{
// New thread for the progress bar.
Thread progressBarThread = new Thread(new ThreadStart(() =>
{
// Populating the progress bar window.
this.progressAndcancelWindow = new VentanaDeProgreso(this);
progressAndcancelWindow.Show();
// Chenge the state of the wait event.
this.eventWait.Set();
Dispatcher.Run();
}));
progressBarThread.SetApartmentState(ApartmentState.STA);
progressBarThread.IsBackground = true;
progressBarThread.Start();
this.eventWait.WaitOne();
}
// Get the current revit document.
Document documentoActivo = aplicacionDeLaIU.ActiveUIDocument.Document;
// Code to simulate the revit command operation.
for (int i = 0;
i <= 100;
i++)
{
// Code to be executed if a cancellation has been requested.
if (this.CancellationRequested)
{
TaskDialog.Show("Test", "Cancel");
this.progressAndcancelWindow.Dispatcher.Invoke(new Action(this.progressAndcancelWindow.Close));
return;
}
this.progressAndcancelWindow.ActualizarProgreso($"loop number: {i}", i, 100);
Thread.Sleep(100);
}
this.progressAndcancelWindow.Dispatcher.Invoke(new Action(this.progressAndcancelWindow.Close));
TaskDialog.Show("Test", "END");
}
public string GetName()
{
return "test";
}
}
Implementing an external command to register the external event and populate the main window
public class Class1 : IExternalCommand
{
public Result Execute(
ExternalCommandData externalCommandData,
ref string message,
ElementSet elements)
{
// Registering the external event.
GestorDeEventoExterno externalEventHandler = new GestorDeEventoExterno();
ExternalEvent externalEvent = ExternalEvent.Create(externalEventHandler);
// Populating the main window.
VentanaPrincipal mainWindow = new VentanaPrincipal(
externalEvent);
mainWindow.Show();
return Result.Succeeded;
}
}
Finally, the code behind of the progress bar window
public partial class VentanaDeProgreso : Window
{
private GestorDeEventoExterno externalEventHandler;
public void ActualizarProgreso(
string texto,
int valorActual,
int valortotal = 100)
{
this.Dispatcher.Invoke(
new Action<string, int, int>(
delegate (string txt, int vActual, int vTotal)
{
this.IndicadorDeProgreso.Value = valorActual;
this.IndicadorDeProgreso.Maximum = vTotal;
this.Texto.Text = txt;
}),
System.Windows.Threading.DispatcherPriority.Background,
texto,
valorActual,
valortotal);
}
private void Button_Click(object sender, RoutedEventArgs e)
{
// Asignación de valor verdadero a la propiedad de cancelación solicitada del evento externo.
this.externalEventHandler.CancellationRequested = true;
}
public VentanaDeProgreso(GestorDeEventoExterno externalEventHandler)
{
InitializeComponent();
this.externalEventHandler= externalEventHandler;
}
}
AS you can see, the progress window has the external event handler as a property and the cancel button click event sets the property 'CancellationRequested'.
My question is: How can I improve it?

Answer 1

You do not need an external event to cancel your command.
You only need an external event to cancel submit a request to execute Revit API functionality from some context in which it is not available.
Your cancellation requires no Revit API functionality, just your own stuff, hence no external event.
Therefore, you can restructure the whole solution much more simply. Kiss!