A Wpf sample for using Xceeds BusyIndicator in a decoupled, testable and MVVM-friendly way with Caliburn.Micro and AutoFac using including support for cancellation and optional progress.
Add an IBusyViewModel to your main view model and bind it to a BusyIndicator in your view, e.g. in the view model
public class AppViewModel : Screen, IAppViewModel
{
public IBusyViewModel BusyIndicator { get; }
public AppViewModel(IBusyViewModel busyIndicator, ...)
{
...
and in the view
...
<xctk:BusyIndicator IsBusy="{Binding BusyIndicator.IsBusy}">
<xctk:BusyIndicator.BusyContent>
...
</xctk:BusyIndicator.BusyContent>
<... main view goes here .. >
</xctk:BusyIndicator>
Don't forget to register an IBusyViewModel implementation in the bootstrapper
protected override void ConfigureContainer(ContainerBuilder builder)
{
builder.RegisterType<BusyViewModel>()
.As<IBusyViewModel>()
.InstancePerLifetimeScope();
...
}
To fire off a long running task from anywhere, publish a StartTaskMessage to the Caliburn IEventAggregator like this
public void Start()
{
var message = new StartTaskMessage(MyLongRunningTask,
$"Waiting for 'long running task'...");
_events.PublishOnUIThread(message);
}
public bool CanStart => _events.HandlerExistsFor(typeof(StartTaskMessage));
private static void MyLongRunningTask(CancellationToken token, IProgress<int> progress)
{
const int n = 20;
var duration = TimeSpan.FromSeconds(20);
for (int i = 1; i <= n; i++)
{
token.ThrowIfCancellationRequested();
Thread.Sleep( (int)(duration.TotalMilliseconds / n) );
progress?.Report((100 * i) / n);
}
}
Cancellation support in TPL is great, except when you can't use it. When restricted to synchronous calls with an external legacy API you cannot pass in a cancellation token - you just have to wait until the call returns successfully or exceptionally (e.g. timeout exceeded). An option for this kind of scenarios, although not recommended, is aborting threads as suggested here i.e.
var t = Thread.CurrentThread;
using (_ct.Token.Register(t.Abort))
{
try { action(); }
catch (ThreadAbortException ex)
{
throw new OperationCanceledException("Blocking thread was canceled", ex);
}
}
A Ribbon must be placed in a RibbonWindow. Wrapping a Ribbon inside a BusyIndicator pretty much works like expected, i.e. when busy the ribbon gets disabled. However, keytips and commands in views or tabs can still be triggered. You don't want the user starting another action while busy. So to prevent this also minimize & hide the ribbon like this
<RibbonWindow.Resources>
<busyindicator:BooleanToVisibilityConverter True="Hidden" False="Visible" x:Key="InverseBoolToVisible"/>
</RibbonWindow.Resources>
<...
<Ribbon IsMinimized="{Binding BusyIndicator.IsBusy}"
Visibility="{Binding BusyIndicator.IsBusy, Converter={StaticResource InverseBoolToVisible}}"
Focusable="False" KeyboardNavigation.TabNavigation="Contained"
WindowIconVisibility="Visible">