BusyResultWrapper

BusyResultWrapper.cs

//Original Idea: http://blog.smoothfriction.nl/archive/2012/05/07/silverlight-busyindicator-in-caliburn-micro-pt-2-again.aspx



//A simpler solution:

    public interface IBusy
    {
        bool IsBusy { get; set; }
    }
	
/*
If some ViewModel implements this interface, then there will be a public property 
named IsBusy, so we can easilly bind to that property:
*/
	
	public class SomeViewModel: Screen, IBusy
	{
		public bool IsBusy
		{
			get { return _isBusy; }
			set
			{
				if (value.Equals(_isBusy)) return;
				_isBusy = value;
				NotifyOfPropertyChange(() => IsBusy);
			}
		}
	}

/* 
    The trick is to create a Wrapper class that decorates the SequentialResult of CM:
*/

    internal class BusyResultWrapper : IResult
    {
        private readonly SequentialResult _inner;
        private IBusy _busy;

        public BusyResultWrapper(SequentialResult inner)
        {
            if (inner == null)
                throw new ArgumentNullException("inner");

            _inner = inner;
        }

        public void Execute(ActionExecutionContext context)
        {
            _busy = context.Target as IBusy;
            if (_busy != null)
                _busy.IsBusy = true;

            _inner.Completed += OnCompleted;
            _inner.Execute(context);
        }

        public event EventHandler<ResultCompletionEventArgs> Completed;

        public void OnCompleted(object sender, ResultCompletionEventArgs resultCompletionEventArgs)
        {
            _inner.Completed -= OnCompleted;

            if (_busy != null)
                _busy.IsBusy = false;

            var handler = Completed;
            if (handler != null) handler(sender, resultCompletionEventArgs);
        }
    }
	
	//In the view, insert a BusyIndicator control named IsBusy:
	
	 <toolkit:BusyIndicator x:Name="IsBusy">
		Some content here...
	 </toolkit:BusyIndicator>
	 
	 
	/* to ensure CaliburnMicro will apply convention for binding the busy indicator, add a convention overriding the Configure of bootstrapper: */

       //your bootstrapper class
	 
        protected override void Configure()
        {
            ConventionManager.AddElementConvention<BusyIndicator>(BusyIndicator.IsBusyProperty, "IsBusy", null);

            Coroutine.CreateParentEnumerator = enumerator =>
            {
                var sequ = new SequentialResult(enumerator);
                return new BusyResultWrapper(sequ);
            };
        }


/*Don't forget to set the target of ActionExecutionContext to the ViewModel that implements IBusy before calling the BeginExecute method of Coroutine class*/

public void SomeCommand()
        {
            var context = new ActionExecutionContext {Target = this};

            Coroutine.BeginExecute(SaveData(), context, (s, e) => Refresh());
        }