WPF UI Thread Dispatcher

A simple implemention for calling asych methods from the UI

Examples

 dispatcher.ExecuteOnMainUIThread(CommandManager.InvalidateRequerySuggested);
dispatcher.Execute(() =>
                                    {
                                       SomeLongRunningMethodHere();
                                    });

The interface

public interface IDispatcher { void Execute(Action action); void ExecuteOnMainUIThread(Action action); } }

Synchronous for use in Testing

 public class SynchronousDispatcher: IDispatcher {  
   public void Execute(Action action) {  
  action();  
}  

public void ExecuteOnMainUIThread(Action action) {
  action();
}   } ## Asynchronous for use by the application at run time

public class AsynchronousDispatcher: IDispatcher {
public void Execute(Action action) {
  action.BeginInvoke(CallBack, action);
}

public void ExecuteOnMainUIThread(Action action) {
  Dispatcher dispatcher;

  if (Application.Current != null) {
    dispatcher = Application.Current.Dispatcher;
  } else {
    dispatcher = Dispatcher.CurrentDispatcher;
  }

  dispatcher.Invoke(action);
}

private void CallBack(IAsyncResult result) {
  try {
    ((Action) result.AsyncState).EndInvoke(result);
  } catch (Exception ex) { // Need to raise the exception on the main thread ExecuteOnMainUIThread(() => { throw ex; } ); } finally { result.AsyncWaitHandle.Close(); }

  }
}

Published: 26/05/2010

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