//===================================================================================
// Microsoft patterns & practices
// Composite Application Guidance for Windows Presentation Foundation and Silverlight
//===================================================================================
// Copyright (c) Microsoft Corporation. All rights reserved.
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE.
//===================================================================================
// The example companies, organizations, products, domain names,
// e-mail addresses, logos, people, places, and events depicted
// herein are fictitious. No association with any real company,
// organization, product, domain name, email address, logo, person,
// places, or events is intended or should be inferred.
//===================================================================================
using System;
using System.Windows;
using System.Windows.Input;
using System.Windows.Threading;
namespace Microsoft.Practices.Composite.Presentation.Commands
{
public partial class CompositeCommand
{
/// <summary>
/// Raises <see cref="ICommand.CanExecuteChanged"/> on the UI thread so every
/// command invoker can requery <see cref="ICommand.CanExecute"/> to check if the
/// <see cref="CompositeCommand"/> can execute.
/// </summary>
protected virtual void OnCanExecuteChanged()
{
Dispatcher dispatcher = null;
if (Application.Current != null)
{
dispatcher = Application.Current.Dispatcher;
}
EventHandler canExecuteChangedHandler = CanExecuteChanged;
if (canExecuteChangedHandler == null) return;
if (dispatcher != null && !dispatcher.CheckAccess())
{
dispatcher.BeginInvoke(DispatcherPriority.Normal,
(Action)OnCanExecuteChanged);
}
else
{
canExecuteChangedHandler(this, EventArgs.Empty);
}
}
}
}