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//---------------------------------------------------------------------------
//
// <copyright file="WindowVisualStateTracker.cs" company="Microsoft">
// Copyright (C) Microsoft Corporation. All rights reserved.
// </copyright>
//
//
// 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
}
}
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