DispatcherObject.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Base / System / Windows / Threading / DispatcherObject.cs / 1305600 / DispatcherObject.cs
                        

                        
                            using System; 
using System.Windows;
using System.Threading;
using MS.Internal.WindowsBase;               // FriendAccessAllowed
 
namespace System.Windows.Threading
{ 
    ///  
    ///     A DispatcherObject is an object associated with a
    ///     .  A DispatcherObject instance should 
    ///     only be access by the dispatcher's thread.
    /// 
    /// 
    ///     Subclasses of  should enforce thread 
    ///     safety by calling  on all their public
    ///     methods to ensure the calling thread is the appropriate thread. 
    ///      
    ///     DispatcherObject cannot be independently instantiated; that is,
    ///     all constructors are protected. 
    /// 
    public abstract class DispatcherObject
    {
        ///  
        ///     Returns the  that this
        ///      is associated with. 
        ///  
        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Advanced)]
        public Dispatcher Dispatcher 
        {
            get
            {
                // This property is free-threaded. 

                return _dispatcher; 
            } 
        }
 
        // This method allows certain derived classes to break the dispatcher affinity
        // of our objects.
        [FriendAccessAllowed] // Built into Base, also used by Framework.
        internal void DetachFromDispatcher() 
        {
            _dispatcher = null; 
         } 

        ///  
        ///     Checks that the calling thread has access to this object.
        /// 
        /// 
        ///     Only the dispatcher thread may access DispatcherObjects. 
        ///     

        ///     This method is public so that any thread can probe to 
        ///     see if it has access to the DispatcherObject. 
        /// 
        ///  
        ///     True if the calling thread has access to this object.
        /// 
        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        public bool CheckAccess() 
        {
            // This method is free-threaded. 
 
            bool accessAllowed = true;
            Dispatcher dispatcher = _dispatcher; 

            // Note: a DispatcherObject that is not associated with a
            // dispatcher is considered to be free-threaded.
            if(dispatcher != null) 
            {
                accessAllowed = dispatcher.CheckAccess(); 
            } 

            return accessAllowed; 
        }

        /// 

        ///     Verifies that the calling thread has access to this object. 
        /// 
        ///  
        ///     Only the dispatcher thread may access DispatcherObjects. 
        ///     

        ///     This method is public so that derived classes can probe to 
        ///     see if the calling thread has access to itself.
        /// 
        [System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
        public void VerifyAccess() 
        {
            // This method is free-threaded. 
 
            Dispatcher dispatcher = _dispatcher;
 
            // Note: a DispatcherObject that is not associated with a
            // dispatcher is considered to be free-threaded.
            if(dispatcher != null)
            { 
                dispatcher.VerifyAccess();
            } 
        } 

        /// 
 
        ///     Instantiate this object associated with the current Dispatcher.
        /// 
        protected DispatcherObject()
        { 
            _dispatcher = Dispatcher.CurrentDispatcher;
        } 
 
        private Dispatcher _dispatcher;
    } 
}


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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