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//---------------------------------------------------------------------------
//
// <copyright file="FocusTracker.cs" company="Microsoft">
// Copyright (C) Microsoft Corporation. All rights reserved.
// </copyright>
//
//
// Description: Class that tracks Win32 focus changes
//
// History:
// 06/17/2003 : BrendanM Ported to WCP
//
//---------------------------------------------------------------------------
using System;
using System.Windows.Automation;
using System.Windows.Automation.Provider;
using System.Diagnostics;
using MS.Win32;
namespace MS.Internal.Automation
{
// Class that tracks Win32 focus changes
internal class FocusTracker : WinEventWrap
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
// Ctor - provide the WinEvent identifiers used to track focus changes
internal FocusTracker()
: base(_eventIds)
{
// 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
// WinEventProc - override to process WinEvents
internal override void WinEventProc(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
if (hwnd != IntPtr.Zero)
{
switch(eventId)
{
case NativeMethods.EVENT_OBJECT_FOCUS: OnEventObjectFocus(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_SYSTEM_MENUSTART: OnEventSystemMenuStart(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_SYSTEM_MENUEND: OnEventSystemMenuEnd(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_SYSTEM_SWITCHSTART: OnEventSystemMenuStart(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_SYSTEM_SWITCHEND: OnEventSystemMenuEnd(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_OBJECT_DESTROY: OnEventObjectDestroy(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_SYSTEM_MENUPOPUPSTART: OnEventSystemMenuPopupStart(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_SYSTEM_CAPTURESTART: OnEventSystemCaptureStart(eventId, hwnd, idObject, idChild, eventTime); break;
case NativeMethods.EVENT_SYSTEM_CAPTUREEND: OnEventSystemCaptureEnd(eventId, hwnd, idObject, idChild, eventTime); break;
}
}
}
#endregion Internal Methods
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#region Private Methods
// HandleFocusChange - Called when a WinEvent we're listening to indicates the
// focus has changed. This is where the callback to the client is queued.
private void HandleFocusChange(IntPtr hwnd, Accessible acc, int idObject, int idChild, uint eventTime)
{
// If there is an hwnd then notify of a focus change
if (hwnd != IntPtr.Zero)
{
Debug.Assert(acc != null, "HandleFocusChange got hwnd and null IAccessible");
// Create an event args and get the source logical element
AutomationFocusChangedEventArgs e = new InternalAutomationFocusChangedEventArgs(idObject, idChild, eventTime);
AutomationElement srcEl = GetFocusedElementFromWinEvent(hwnd, idObject, idChild);
if (srcEl == null)
{
// Don't raise focus change events for UI that is gone. This has been seen when toolbar menus are
// being manipulated (e.g. mnu.SubMenu("File").MenuItems("Close").Click() in MITA). We should be
// seeing another focus change soon and with that event we can re-establish focus.
return;
}
// Check that item is actually focused
// Don't do this for statics - the controls in the color picker are statics, and
// they get focus, but OLEACC assumes statics don't get focus, so never sets the
// focus bit. So, for now, assume statics that send focus do actually have focus.
if (!Accessible.IsStatic(hwnd) && !Accessible.IsComboDropdown(hwnd))
{
// instead of depending on oleacc to see if something has focus ask provider
if (!(bool)srcEl.GetCurrentPropertyValue(AutomationElement.HasKeyboardFocusProperty))
{
return;
}
}
// Do notifies
ClientEventManager.RaiseEventInThisClientOnly(AutomationElement.AutomationFocusChangedEvent, srcEl, e);
}
// Keep track of where we are right now (may be unknown/null)
_accCurrent = acc;
}
// We need to treat MSAA's FOCUS winevents differently depending on the OBJID -
// OBJID_CLIENT gets routed to the proxies; _MENU and _SYSMENU get speical treatment.
private AutomationElement GetFocusedElementFromWinEvent(IntPtr hwnd, int idObject, int idChild)
{
try
{
IRawElementProviderSimple provider = null;
// These are the only object types that oleacc proxies allow to take focus.
// (Native IAccessibles can send focus for other custom OBJID valus, but those are no use
// to us.)
// Try and get providers for them ourself - if we don't get anything, then
// defer to core to get the element for the HWND itself.
if (idObject == UnsafeNativeMethods.OBJID_CLIENT)
{
// regular focus - pass it off to a proxy...
provider = ProxyManager.ProxyProviderFromHwnd(NativeMethods.HWND.Cast(hwnd), idChild, UnsafeNativeMethods.OBJID_CLIENT);
}
else if (idObject == UnsafeNativeMethods.OBJID_MENU)
{
// menubar focus - see if there's a menubar pseudo-proxy registered...
ClientSideProviderFactoryCallback factory = ProxyManager.NonClientMenuBarProxyFactory;
if (factory != null)
{
provider = factory(hwnd, idChild, idObject);
}
}
else if (idObject == UnsafeNativeMethods.OBJID_SYSMENU)
{
// system menu box focus - see if there's a sysmenu pseudo-proxy registered...
ClientSideProviderFactoryCallback factory = ProxyManager.NonClientSysMenuProxyFactory;
if (factory != null)
{
provider = factory(hwnd, idChild, idObject);
}
}
else if (idObject <= 0)
{
return null;
}
else
{
// This covers OBJID_CLIENT and custom OBJID cases.
// Pass it to the proxy manager: most proxies will just handle OBJID_CLIENT,
// but the MSAA proxy can potentally handle other OBJID values.
provider = ProxyManager.ProxyProviderFromHwnd(NativeMethods.HWND.Cast(hwnd), idChild, idObject);
}
if(provider != null)
{
// Ask the fragment root if any of its children really have the focus
IRawElementProviderFragmentRoot fragment = provider as IRawElementProviderFragmentRoot;
if (fragment != null)
{
// if we get back something that is different than what we started with and its not null
// use that instead. This is here to get the subset link in the listview but could be usefull
// for listview subitems as well.
IRawElementProviderSimple realFocus = fragment.GetFocus();
if(realFocus != null && !Object.ReferenceEquals(realFocus, provider))
{
provider = realFocus;
}
}
SafeNodeHandle hnode = UiaCoreApi.UiaNodeFromProvider(provider);
return AutomationElement.Wrap(hnode);
}
else
{
// Didn't find a proxy to handle this hwnd - pass off to core...
return AutomationElement.FromHandle(hwnd);
}
}
catch( Exception e )
{
if( Misc.IsCriticalException( e ) )
throw;
return null;
}
}
// OnEventObjectFocus - process an EventObjectFocus WinEvent.
private void OnEventObjectFocus(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
Accessible acc = Accessible.Create(hwnd, idObject, idChild);
if (acc == null)
{
return;
}
// Keep track of last focused non-menu item, so we can restore focus when we leave menu mode
if (!_fInMenu)
{
_accLastBeforeMenu = acc;
_hwndLastBeforeMenu = hwnd;
_idLastObject = idObject;
_idLastChild = idChild;
}
HandleFocusChange(hwnd, acc, idObject, idChild, eventTime);
}
// OnEventSystemMenuStart - process an EventSystemMenuStart WinEvent.
private void OnEventSystemMenuStart(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
// No immediate effect on focus - we expect to get a FOCUS event after this.
_fInMenu = true;
}
// OnEventSystemMenuEnd - process an EventSystemMenuEnd WinEvent.
private void OnEventSystemMenuEnd(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
// Restore focus to where it was before the menu appeared
if (_fInMenu)
{
_fInMenu = false;
if (_accLastBeforeMenu != null)
{
HandleFocusChange(_hwndLastBeforeMenu, _accLastBeforeMenu, _idLastObject, _idLastChild, eventTime);
}
}
}
// OnEventObjectDestroy - process an EventObjectDestroy WinEvent.
private void OnEventObjectDestroy(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
// Check if still alive. Ignore caret destroys - we're only interesed in 'real' objects here...
if (idObject != UnsafeNativeMethods.OBJID_CARET && _accCurrent != null)
{
bool fDead = false;
try
{
int dwState = _accCurrent.State;
IntPtr hwndCur = _accCurrent.Window;
if (hwndCur == IntPtr.Zero || !SafeNativeMethods.IsWindow(NativeMethods.HWND.Cast(hwndCur)))
{
fDead = true;
}
}
catch( Exception e )
{
if( Misc.IsCriticalException( e ) )
throw;
fDead = true;
}
if (fDead)
{
// It's dead...
HandleFocusChange(IntPtr.Zero, null, 0, 0, eventTime);
}
}
}
// OnEventSystemMenuPopupStart - process an EventSystemMenuPopupStart WinEvent.
private void OnEventSystemMenuPopupStart(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
Accessible acc = Accessible.Create(hwnd, idObject, idChild);
if( acc == null )
return;
HandleFocusChange(hwnd, acc, idObject, idChild, eventTime);
}
// OnEventSystemCaptureStart - process an EventSystemCaptureStart WinEvent.
private void OnEventSystemCaptureStart(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
// Deal only with Combolbox dropdowns...
if (Accessible.IsComboDropdown(hwnd))
{
// Need to get id of focused item...
try
{
IntPtr i = Misc.SendMessageTimeout(NativeMethods.HWND.Cast(hwnd), UnsafeNativeMethods.LB_GETCURSEL, IntPtr.Zero, IntPtr.Zero);
Accessible acc = Accessible.Create(hwnd, UnsafeNativeMethods.OBJID_CLIENT, i.ToInt32() + 1);
if (acc == null)
return;
HandleFocusChange(hwnd, acc, idObject, idChild, eventTime);
}
catch (TimeoutException)
{
// Ignore
}
}
}
// OnEventSystemCaptureEnd - process an EventSystemCaptureEnd WinEvent.
private void OnEventSystemCaptureEnd(int eventId, IntPtr hwnd, int idObject, int idChild, uint eventTime)
{
// Deal only with Combolbox dropdowns...
if (Accessible.IsComboDropdown(hwnd))
{
SafeNativeMethods.GUITHREADINFO guiThreadInfo = new SafeNativeMethods.GUITHREADINFO();
if (!Misc.GetGUIThreadInfo(0, ref guiThreadInfo))
{
return;
}
Accessible acc = Accessible.Create(guiThreadInfo.hwndFocus, UnsafeNativeMethods.OBJID_CLIENT, 0);
if (acc == null)
return;
HandleFocusChange(hwnd, acc, idObject, idChild, eventTime);
}
}
#endregion Private Methods
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
#region Private Fields
private static int [] _eventIds = new int [] {
NativeMethods.EVENT_OBJECT_FOCUS,
NativeMethods.EVENT_SYSTEM_MENUSTART,
NativeMethods.EVENT_SYSTEM_MENUPOPUPSTART,
NativeMethods.EVENT_SYSTEM_MENUEND,
NativeMethods.EVENT_OBJECT_DESTROY,
NativeMethods.EVENT_SYSTEM_CAPTURESTART,
NativeMethods.EVENT_SYSTEM_CAPTUREEND,
NativeMethods.EVENT_SYSTEM_SWITCHSTART,
NativeMethods.EVENT_SYSTEM_SWITCHEND
};
private Accessible _accCurrent; // the IAccessible currently being handled
private Accessible _accLastBeforeMenu; // the last IAccessible before a menu got focus
private IntPtr _hwndLastBeforeMenu; // the last hwnd before a menu got focus
private int _idLastObject; // the last idObject before a menu got focus
private int _idLastChild; // the last idChild before a menu got focus
private bool _fInMenu; // true if there's a menu up
#endregion Private Fields
}
}
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