WindowVisualStateTracker.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / AccessibleTech / longhorn / Automation / UIAutomationClient / MS / Internal / Automation / WindowVisualStateTracker.cs / 1 / WindowVisualStateTracker.cs
                        

                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: Class used to track the visual appearance of Windows and make sure any events 
// are propogated to that new UI.
// 
// History:
//  01/05/2005 : Miw Created
//
//--------------------------------------------------------------------------- 

using System; 
using System.Windows.Automation; 
using MS.Win32;
 
namespace MS.Internal.Automation
{
    // Class used to track new UI appearing and make sure any events
    // are propogated to that new UI. 
    internal class WindowVisualStateTracker : WinEventWrap
    { 
        //----------------------------------------------------- 
        //
        //  Constructors 
        //
        //-----------------------------------------------------

        #region Constructors 

        internal WindowVisualStateTracker() 
            : base(new int[] { NativeMethods.EVENT_OBJECT_LOCATIONCHANGE }) 
        {
            // Intentionally not setting the callback for the base WinEventWrap since the WinEventProc override 
            // in this class calls RaiseEventInThisClientOnly to actually raise the event to the client.
        }

        #endregion Constructors 

 
        //------------------------------------------------------ 
        //
        //  Internal Methods 
        //
        //-----------------------------------------------------

        #region Internal Methods 

        internal override void WinEventProc(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime) 
        { 
            // ignore any event not pertaining directly to the window
            if (idObject != UnsafeNativeMethods.OBJID_WINDOW) 
            {
                return;
            }
 
            // Ignore if this is a bogus hwnd (shouldn't happen)
            if (hwnd == IntPtr.Zero) 
            { 
                return;
            } 

            OnStateChange(hwnd, idObject, idChild);
        }
 
        #endregion Internal Methods
 
 
        //------------------------------------------------------
        // 
        //  Private Methods
        //
        //------------------------------------------------------
 
        #region Private Methods
 
        private void OnStateChange(IntPtr hwnd, int idObject, int idChild) 
        {
            NativeMethods.HWND nativeHwnd = NativeMethods.HWND.Cast(hwnd); 

            // Ignore windows that have been destroyed
            if (!SafeNativeMethods.IsWindow(nativeHwnd))
            { 
                return;
            } 
 
            AutomationElement rawEl = AutomationElement.FromHandle(hwnd);
 
            // Raise this event only for elements with the WindowPattern.
            object patternObject;
            if (!rawEl.TryGetCurrentPattern(WindowPattern.Pattern, out patternObject))
                return; 

            Object windowVisualState = rawEl.GetPatternPropertyValue(WindowPattern.WindowVisualStateProperty, false); 
 
            // if has no state value just return
            if (!(windowVisualState is WindowVisualState)) 
            {
                return;
            }
 
            WindowVisualState state = (WindowVisualState)windowVisualState;
 
            // Filter... avoid duplicate events 
            if (hwnd == _lastHwnd && state == _lastState)
            { 
                return;
            }

            AutomationPropertyChangedEventArgs e = new AutomationPropertyChangedEventArgs( 
                                    WindowPattern.WindowVisualStateProperty,
                                    null, 
                                    state); 

            ClientEventManager.RaiseEventInThisClientOnly(AutomationElement.AutomationPropertyChangedEvent, rawEl, e); 

            // save the last hwnd/rect for filtering out duplicates
            _lastHwnd = hwnd;
            _lastState = state; 
        }
 
        #endregion Private Methods 

 
        //-----------------------------------------------------
        //
        //  Private Fields
        // 
        //------------------------------------------------------
 
        #region Private Fields 

        private WindowVisualState _lastState;      // keep track of last visual state 
        private IntPtr _lastHwnd;                  // and hwnd for dup checking

        #endregion Private Fields
    } 
}

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

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