ComponentDispatcherThread.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Base / System / Windows / Interop / ComponentDispatcherThread.cs / 1 / ComponentDispatcherThread.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

using System; 
using MS.Win32; 
using System.Globalization;
using System.Security; 
using System.Security.Permissions;
using MS.Internal.WindowsBase;

namespace System.Windows.Interop 
{
    ///  
    /// This is a class used to implement per-thread instance of the ComponentDispatcher. 
    ///
    internal class ComponentDispatcherThread 
    {
        /// 
        /// Returns true if one or more components has gone modal.
        /// Although once one component is modal a 2nd shouldn't. 
        ///
        public bool IsThreadModal 
        { 
            get
            { 
                return (_modalCount > 0);
            }
        }
 
        /// 
        /// Returns "current" message.   More exactly the last MSG Raised. 
        /// 
        /// 
        ///     Critical: This is blocked off as defense in depth to avoid leaking message information 
        /// 
        public MSG CurrentKeyboardMessage
        {
            [SecurityCritical] 
            get
            { 
                return _currentKeyboardMSG; 
            }
 
            [SecurityCritical]
            set
            {
                _currentKeyboardMSG = value; 
            }
        } 
 
        /// 
        /// A component calls this to go modal.  Current thread wide only. 
        ///
        /// 
        ///     Critical: This is blocked off as defense in depth
        ///  
        [SecurityCritical]
        public void PushModal() 
        { 
            _modalCount += 1;
            if(1 == _modalCount) 
            {
                if(null != _enterThreadModal)
                    _enterThreadModal(null, EventArgs.Empty);
            } 
        }
 
        ///  
        /// A component calls this to end being modal.
        /// 
        /// 
        ///     Critical: This is blocked off as defense in depth to avoid tampering with input
        /// 
        [SecurityCritical] 
        public void PopModal()
        { 
            _modalCount -= 1; 
            if(0 == _modalCount)
            { 
                if(null != _leaveThreadModal)
                    _leaveThreadModal(null, EventArgs.Empty);
            }
            if(_modalCount < 0) 
                _modalCount = 0;    // Throwing is also good
        } 
 
        /// 
        /// The message loop pumper calls this when it is time to do idle processing. 
        ///
        /// 
        ///     Critical: This is blocked off as defense in depth
        ///  
        [SecurityCritical]
        public void RaiseIdle() 
        { 
            if(null != _threadIdle)
                _threadIdle(null, EventArgs.Empty); 
        }

        /// 
        /// The message loop pumper calls this for every keyboard message. 
        /// 
        ///  
        ///     Critical: This is blocked off as defense in depth to prevent message leakage 
        /// 
        [SecurityCritical] 
        public bool RaiseThreadMessage(ref MSG msg)
        {
            bool handled=false;
 
            if(null != _threadFilterMessage)
                _threadFilterMessage(ref msg, ref handled); 
 
            if(handled)
                return handled; 

            if(null != _threadPreprocessMessage)
                _threadPreprocessMessage(ref msg, ref handled);
 
            return handled;
        } 
 
        /// 
        /// Components register delegates with this event to handle 
        /// thread idle processing.
        ///
        /// 
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information 
        /// 
        public event EventHandler ThreadIdle 
        { 
            [SecurityCritical]
            add 
            {
                _threadIdle += value;
            }
            [SecurityCritical] 
            remove
            { 
                _threadIdle -= value; 
            }
        } 
        /// 
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information
        /// 
        [SecurityCritical] 
        private event EventHandler _threadIdle;
 
 
        /// 
        /// Components register delegates with this event to handle 
        /// Keyboard Messages (first chance processing).
        ///
        /// 
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information 
        /// 
        public event ThreadMessageEventHandler ThreadFilterMessage 
        { 
            [SecurityCritical]
            add 
            {
                _threadFilterMessage += value;
            }
            [SecurityCritical] 
            remove
            { 
                _threadFilterMessage -= value; 
            }
        } 
        /// 
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information
        /// 
        [SecurityCritical] 
        private event ThreadMessageEventHandler _threadFilterMessage;
 
        ///  
        /// Components register delegates with this event to handle
        /// Keyboard Messages (second chance processing). 
        ///
        /// 
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information
        ///  
        public event ThreadMessageEventHandler ThreadPreprocessMessage
        { 
            [SecurityCritical] 
            add
            { 
                _threadPreprocessMessage += value;
            }
            [SecurityCritical]
            remove 
            {
                _threadPreprocessMessage -= value; 
            } 
        }
        ///  
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information
        /// 
        [SecurityCritical]
        private event ThreadMessageEventHandler _threadPreprocessMessage; 

        ///  
        /// Components register delegates with this event to handle 
        /// a component on this thread has "gone modal", when previously none were.
        /// 
        /// 
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information
        /// 
        public event EventHandler EnterThreadModal 
        {
            [SecurityCritical] 
            add 
            {
                _enterThreadModal += value; 
            }
            [SecurityCritical]
            remove
            { 
                _enterThreadModal -= value;
            } 
        } 
        /// 
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information 
        /// 
        [SecurityCritical]
        private event EventHandler _enterThreadModal;
 
        /// 
        /// Components register delegates with this event to handle 
        /// all components on this thread are done being modal. 
        ///
        ///  
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information
        /// 
        public event EventHandler LeaveThreadModal
        { 
            [SecurityCritical]
            add 
            { 
                _leaveThreadModal += value;
            } 
            [SecurityCritical]
            remove
            {
                _leaveThreadModal -= value; 
            }
        } 
        ///  
        ///     Critical: This is blocked off as defense in depth and is used to transmit input related information
        ///  
        [SecurityCritical]
        private event EventHandler _leaveThreadModal;

        private int _modalCount; 

        ///  
        ///     Critical: This holds the last message that was recieved 
        /// 
        [SecurityCritical] 
        private MSG _currentKeyboardMSG;
    }
}

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