src/common/event.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        event.cpp
   3 // Purpose:     Event classes
   4 // Author:      Julian Smart
   5 // Modified by:
   6 // Created:     01/02/97
   7 // RCS-ID:      $Id$
   8 // Copyright:   (c) Julian Smart and Markus Holzem
   9 // Licence:       wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifdef __GNUG__
  13     #pragma implementation "event.h"
  14 #endif
  15
  16 // For compilers that support precompilation, includes "wx.h".
  17 #include "wx/wxprec.h"
  18
  19 #ifdef __BORLANDC__
  20     #pragma hdrstop
  21 #endif
  22
  23 #ifndef WX_PRECOMP
  24     #include "wx/defs.h"
  25     #include "wx/control.h"
  26     #include "wx/utils.h"
  27     #include "wx/app.h"
  28     #include "wx/dc.h"
  29 #endif
  30
  31 #include "wx/event.h"
  32 #include "wx/validate.h"
  33
  34 #if !USE_SHARED_LIBRARY
  35     IMPLEMENT_DYNAMIC_CLASS(wxEvtHandler, wxObject)
  36     IMPLEMENT_ABSTRACT_CLASS(wxEvent, wxObject)
  37     IMPLEMENT_DYNAMIC_CLASS(wxCommandEvent, wxEvent)
  38     IMPLEMENT_DYNAMIC_CLASS(wxNotifyEvent, wxCommandEvent)
  39     IMPLEMENT_DYNAMIC_CLASS(wxScrollEvent, wxCommandEvent)
  40     IMPLEMENT_DYNAMIC_CLASS(wxMouseEvent, wxEvent)
  41     IMPLEMENT_DYNAMIC_CLASS(wxKeyEvent, wxEvent)
  42     IMPLEMENT_DYNAMIC_CLASS(wxSizeEvent, wxEvent)
  43     IMPLEMENT_DYNAMIC_CLASS(wxPaintEvent, wxEvent)
  44     IMPLEMENT_DYNAMIC_CLASS(wxEraseEvent, wxEvent)
  45     IMPLEMENT_DYNAMIC_CLASS(wxMoveEvent, wxEvent)
  46     IMPLEMENT_DYNAMIC_CLASS(wxFocusEvent, wxEvent)
  47     IMPLEMENT_DYNAMIC_CLASS(wxCloseEvent, wxEvent)
  48     IMPLEMENT_DYNAMIC_CLASS(wxShowEvent, wxEvent)
  49     IMPLEMENT_DYNAMIC_CLASS(wxMaximizeEvent, wxEvent)
  50     IMPLEMENT_DYNAMIC_CLASS(wxIconizeEvent, wxEvent)
  51     IMPLEMENT_DYNAMIC_CLASS(wxMenuEvent, wxEvent)
  52     IMPLEMENT_DYNAMIC_CLASS(wxJoystickEvent, wxEvent)
  53     IMPLEMENT_DYNAMIC_CLASS(wxDropFilesEvent, wxEvent)
  54     IMPLEMENT_DYNAMIC_CLASS(wxActivateEvent, wxEvent)
  55     IMPLEMENT_DYNAMIC_CLASS(wxInitDialogEvent, wxEvent)
  56     IMPLEMENT_DYNAMIC_CLASS(wxSysColourChangedEvent, wxEvent)
  57     IMPLEMENT_DYNAMIC_CLASS(wxIdleEvent, wxEvent)
  58     IMPLEMENT_DYNAMIC_CLASS(wxUpdateUIEvent, wxCommandEvent)
  59     IMPLEMENT_DYNAMIC_CLASS(wxNavigationKeyEvent, wxCommandEvent)
  60     IMPLEMENT_DYNAMIC_CLASS(wxPaletteChangedEvent, wxEvent)
  61     IMPLEMENT_DYNAMIC_CLASS(wxQueryNewPaletteEvent, wxEvent)
  62
  63     const wxEventTable *wxEvtHandler::GetEventTable() const
  64         { return &wxEvtHandler::sm_eventTable; }
  65
  66     const wxEventTable wxEvtHandler::sm_eventTable =
  67         { (const wxEventTable *)NULL, &wxEvtHandler::sm_eventTableEntries[0] };
  68
  69     const wxEventTableEntry wxEvtHandler::sm_eventTableEntries[] =
  70         { { 0, 0, 0, (wxObjectEventFunction) NULL, (wxObject*) NULL } };
  71
  72 #endif // !USE_SHARED_LIBRARY
  73
  74 #if wxUSE_THREADS
  75 /* To put pending event handlers */
  76 extern wxList *wxPendingEvents;
  77 extern wxCriticalSection *wxPendingEventsLocker;
  78 #endif
  79
  80 /*
  81  * General wxWindows events, covering
  82  * all interesting things that might happen (button clicking, resizing,
  83  * setting text in widgets, etc.).
  84  *
  85  * For each completely new event type, derive a new event class.
  86  *
  87  */
  88
  89 wxEvent::wxEvent(int theId)
  90 {
  91     m_eventType = wxEVT_NULL;
  92     m_eventObject = (wxObject *) NULL;
  93     m_eventHandle = (char *) NULL;
  94     m_timeStamp = 0;
  95     m_id = theId;
  96     m_skipped = FALSE;
  97     m_callbackUserData = (wxObject *) NULL;
  98     m_isCommandEvent = FALSE;
  99 }
 100
 101 void wxEvent::CopyObject(wxObject& object_dest) const
 102 {
 103     wxEvent *obj = (wxEvent *)&object_dest;
 104     wxObject::CopyObject(object_dest);
 105
 106     obj->m_eventType = m_eventType;
 107     obj->m_eventObject = m_eventObject;
 108     obj->m_eventHandle = m_eventHandle;
 109     obj->m_timeStamp = m_timeStamp;
 110     obj->m_id = m_id;
 111     obj->m_skipped = m_skipped;
 112     obj->m_callbackUserData = m_callbackUserData;
 113     obj->m_isCommandEvent = m_isCommandEvent;
 114 }
 115
 116 /*
 117  * Command events
 118  *
 119  */
 120
 121 wxCommandEvent::wxCommandEvent(wxEventType commandType, int theId)
 122 {
 123     m_eventType = commandType;
 124     m_clientData = (char *) NULL;
 125     m_clientObject = (wxClientData *) NULL;
 126     m_extraLong = 0;
 127     m_commandInt = 0;
 128     m_id = theId;
 129     m_commandString = (wxChar *) NULL;
 130     m_isCommandEvent = TRUE;
 131 }
 132
 133 void wxCommandEvent::CopyObject(wxObject& obj_d) const
 134 {
 135     wxCommandEvent *obj = (wxCommandEvent *)&obj_d;
 136
 137     wxEvent::CopyObject(obj_d);
 138
 139     obj->m_clientData   = m_clientData;
 140     obj->m_clientObject = m_clientObject;
 141     obj->m_extraLong    = m_extraLong;
 142     obj->m_commandInt   = m_commandInt;
 143 }
 144
 145 /*
 146  * Scroll events
 147  */
 148
 149 wxScrollEvent::wxScrollEvent(wxEventType commandType,
 150                              int id,
 151                              int pos,
 152                              int orient)
 153              : wxCommandEvent(commandType, id)
 154 {
 155     m_extraLong = orient;
 156     m_commandInt = pos;
 157 }
 158
 159 /*
 160  * Mouse events
 161  *
 162  */
 163
 164 wxMouseEvent::wxMouseEvent(wxEventType commandType)
 165 {
 166     m_eventType = commandType;
 167     m_metaDown = FALSE;
 168     m_altDown = FALSE;
 169     m_controlDown = FALSE;
 170     m_shiftDown = FALSE;
 171     m_leftDown = FALSE;
 172     m_rightDown = FALSE;
 173     m_middleDown = FALSE;
 174     m_x = 0;
 175     m_y = 0;
 176 }
 177
 178 void wxMouseEvent::CopyObject(wxObject& obj_d) const
 179 {
 180     wxMouseEvent *obj = (wxMouseEvent *)&obj_d;
 181
 182     wxEvent::CopyObject(obj_d);
 183
 184     obj->m_metaDown = m_metaDown;
 185     obj->m_altDown = m_altDown;
 186     obj->m_controlDown = m_controlDown;
 187     obj->m_shiftDown = m_shiftDown;
 188     obj->m_leftDown = m_leftDown;
 189     obj->m_rightDown = m_rightDown;
 190     obj->m_middleDown = m_middleDown;
 191     obj->m_x = m_x;
 192     obj->m_y = m_y;
 193 }
 194
 195 // True if was a button dclick event (1 = left, 2 = middle, 3 = right)
 196 // or any button dclick event (but = -1)
 197 bool wxMouseEvent::ButtonDClick(int but) const
 198 {
 199     switch (but)
 200     {
 201         case -1:
 202             return (LeftDClick() || MiddleDClick() || RightDClick());
 203         case 1:
 204             return LeftDClick();
 205         case 2:
 206             return MiddleDClick();
 207         case 3:
 208             return RightDClick();
 209         default:
 210             wxFAIL_MSG(_T("invalid parameter in wxMouseEvent::ButtonDClick"));
 211     }
 212
 213     return FALSE;
 214 }
 215
 216 // True if was a button down event (1 = left, 2 = middle, 3 = right)
 217 // or any button down event (but = -1)
 218 bool wxMouseEvent::ButtonDown(int but) const
 219 {
 220     switch (but)
 221     {
 222         case -1:
 223             return (LeftDown() || MiddleDown() || RightDown());
 224         case 1:
 225             return LeftDown();
 226         case 2:
 227             return MiddleDown();
 228         case 3:
 229             return RightDown();
 230         default:
 231             wxFAIL_MSG(_T("invalid parameter in wxMouseEvent::ButtonDown"));
 232     }
 233
 234     return FALSE;
 235 }
 236
 237 // True if was a button up event (1 = left, 2 = middle, 3 = right)
 238 // or any button up event (but = -1)
 239 bool wxMouseEvent::ButtonUp(int but) const
 240 {
 241     switch (but) {
 242         case -1:
 243             return (LeftUp() || MiddleUp() || RightUp());
 244         case 1:
 245             return LeftUp();
 246         case 2:
 247             return MiddleUp();
 248         case 3:
 249             return RightUp();
 250         default:
 251             wxFAIL_MSG(_T("invalid parameter in wxMouseEvent::ButtonUp"));
 252     }
 253
 254     return FALSE;
 255 }
 256
 257 // True if the given button is currently changing state
 258 bool wxMouseEvent::Button(int but) const
 259 {
 260     switch (but) {
 261         case -1:
 262             return (ButtonUp(-1) || ButtonDown(-1) || ButtonDClick(-1)) ;
 263         case 1:
 264             return (LeftDown() || LeftUp() || LeftDClick());
 265         case 2:
 266             return (MiddleDown() || MiddleUp() || MiddleDClick());
 267         case 3:
 268             return (RightDown() || RightUp() || RightDClick());
 269         default:
 270             wxFAIL_MSG(_T("invalid parameter in wxMouseEvent::Button"));
 271     }
 272
 273     return FALSE;
 274 }
 275
 276 bool wxMouseEvent::ButtonIsDown(int but) const
 277 {
 278     switch (but) {
 279         case -1:
 280             return (LeftIsDown() || MiddleIsDown() || RightIsDown());
 281         case 1:
 282             return LeftIsDown();
 283         case 2:
 284             return MiddleIsDown();
 285         case 3:
 286             return RightIsDown();
 287         default:
 288             wxFAIL_MSG(_T("invalid parameter in wxMouseEvent::ButtonIsDown"));
 289     }
 290
 291     return FALSE;
 292 }
 293
 294 // Find the logical position of the event given the DC
 295 wxPoint wxMouseEvent::GetLogicalPosition(const wxDC& dc) const
 296 {
 297     wxPoint pt(dc.DeviceToLogicalX(m_x), dc.DeviceToLogicalY(m_y));
 298     return pt;
 299 }
 300
 301
 302 /*
 303  * Keyboard events
 304  *
 305  */
 306
 307 wxKeyEvent::wxKeyEvent(wxEventType type)
 308 {
 309     m_eventType = type;
 310     m_shiftDown = FALSE;
 311     m_controlDown = FALSE;
 312     m_metaDown = FALSE;
 313     m_altDown = FALSE;
 314     m_keyCode = 0;
 315 }
 316
 317 void wxKeyEvent::CopyObject(wxObject& obj_d) const
 318 {
 319     wxKeyEvent *obj = (wxKeyEvent *)&obj_d;
 320     wxEvent::CopyObject(obj_d);
 321
 322     obj->m_shiftDown   = m_shiftDown;
 323     obj->m_controlDown = m_controlDown;
 324     obj->m_metaDown    = m_metaDown;
 325     obj->m_altDown     = m_altDown;
 326     obj->m_keyCode     = m_keyCode;
 327 }
 328
 329
 330 /*
 331  * Misc events
 332  */
 333
 334 void wxSizeEvent::CopyObject(wxObject& obj_d) const
 335 {
 336     wxSizeEvent *obj = (wxSizeEvent *)&obj_d;
 337     wxEvent::CopyObject(obj_d);
 338
 339     obj->m_size = m_size;
 340 }
 341
 342 void wxMoveEvent::CopyObject(wxObject& obj_d) const
 343 {
 344     wxMoveEvent *obj = (wxMoveEvent *)&obj_d;
 345     wxEvent::CopyObject(obj_d);
 346
 347     obj->m_pos = m_pos;
 348 }
 349
 350 void wxEraseEvent::CopyObject(wxObject& obj_d) const
 351 {
 352     wxEraseEvent *obj = (wxEraseEvent *)&obj_d;
 353     wxEvent::CopyObject(obj_d);
 354
 355     obj->m_dc = m_dc;
 356 }
 357
 358 void wxActivateEvent::CopyObject(wxObject& obj_d) const
 359 {
 360     wxActivateEvent *obj = (wxActivateEvent *)&obj_d;
 361     wxEvent::CopyObject(obj_d);
 362
 363     obj->m_active = m_active;
 364 }
 365
 366 void wxMenuEvent::CopyObject(wxObject& obj_d) const
 367 {
 368     wxMenuEvent *obj = (wxMenuEvent *)&obj_d;
 369     wxEvent::CopyObject(obj_d);
 370
 371     obj->m_menuId = m_menuId;
 372 }
 373
 374 void wxCloseEvent::CopyObject(wxObject& obj_d) const
 375 {
 376     wxCloseEvent *obj = (wxCloseEvent *)&obj_d;
 377     wxEvent::CopyObject(obj_d);
 378
 379     obj->m_loggingOff = m_loggingOff;
 380     obj->m_veto = m_veto;
 381 #if WXWIN_COMPATIBILITY
 382     obj->m_force = m_force;
 383 #endif
 384     obj->m_canVeto = m_canVeto;
 385 }
 386
 387 void wxShowEvent::CopyObject(wxObject& obj_d) const
 388 {
 389     wxShowEvent *obj = (wxShowEvent *)&obj_d;
 390     wxEvent::CopyObject(obj_d);
 391
 392     obj->m_show = m_show;
 393 }
 394
 395
 396 /*
 397  * Event handler
 398  */
 399
 400 wxEvtHandler::wxEvtHandler()
 401 {
 402     m_nextHandler = (wxEvtHandler *) NULL;
 403     m_previousHandler = (wxEvtHandler *) NULL;
 404     m_enabled = TRUE;
 405     m_dynamicEvents = (wxList *) NULL;
 406     m_isWindow = FALSE;
 407 #if wxUSE_THREADS
 408     m_eventsLocker = new wxCriticalSection();
 409 #endif
 410     m_pendingEvents = (wxList *) NULL;
 411 }
 412
 413 wxEvtHandler::~wxEvtHandler()
 414 {
 415     // Takes itself out of the list of handlers
 416     if (m_previousHandler)
 417         m_previousHandler->m_nextHandler = m_nextHandler;
 418
 419     if (m_nextHandler)
 420         m_nextHandler->m_previousHandler = m_previousHandler;
 421
 422     if (m_dynamicEvents)
 423     {
 424         wxNode *node = m_dynamicEvents->First();
 425         while (node)
 426         {
 427             wxEventTableEntry *entry = (wxEventTableEntry*)node->Data();
 428             if (entry->m_callbackUserData) delete entry->m_callbackUserData;
 429             delete entry;
 430             node = node->Next();
 431         }
 432         delete m_dynamicEvents;
 433     };
 434
 435 #if wxUSE_THREADS
 436     if (m_pendingEvents)
 437       delete m_pendingEvents;
 438
 439     delete m_eventsLocker;
 440 #endif
 441 }
 442
 443 #if wxUSE_THREADS
 444
 445 #ifdef __WXGTK__
 446 extern bool g_isIdle;
 447
 448 extern void wxapp_install_idle_handler();
 449 #endif
 450
 451 bool wxEvtHandler::ProcessThreadEvent(wxEvent& event)
 452 {
 453     wxEvent *event_main;
 454     wxCriticalSectionLocker locker(*m_eventsLocker);
 455
 456
 457     // check that we are really in a child thread
 458     wxASSERT( !wxThread::IsMain() );
 459
 460     if (m_pendingEvents == NULL)
 461       m_pendingEvents = new wxList();
 462
 463     event_main = (wxEvent *)event.Clone();
 464
 465     m_pendingEvents->Append(event_main);
 466
 467     wxPendingEventsLocker->Enter();
 468     wxPendingEvents->Append(this);
 469     wxPendingEventsLocker->Leave();
 470
 471 #ifdef __WXGTK__
 472     if (g_isIdle) wxapp_install_idle_handler();
 473 #endif
 474
 475     return TRUE;
 476 }
 477
 478 void wxEvtHandler::ProcessPendingEvents()
 479 {
 480     wxCriticalSectionLocker locker(*m_eventsLocker);
 481     wxNode *node = m_pendingEvents->First();
 482     wxEvent *event;
 483
 484     while (node != NULL) {
 485       event = (wxEvent *)node->Data();
 486       ProcessEvent(*event);
 487       delete node;
 488       node = m_pendingEvents->First();
 489     }
 490 }
 491 #endif
 492
 493 /*
 494  * Event table stuff
 495  */
 496
 497 bool wxEvtHandler::ProcessEvent(wxEvent& event)
 498 {
 499     // check that our flag corresponds to reality
 500     wxASSERT( m_isWindow == IsKindOf(CLASSINFO(wxWindow)) );
 501
 502     // An event handler can be enabled or disabled
 503     if ( GetEvtHandlerEnabled() )
 504     {
 505 #if wxUSE_THREADS
 506         // Check whether we are in a child thread.
 507         if (!wxThread::IsMain())
 508           return ProcessThreadEvent(event);
 509 #endif
 510         // Handle per-instance dynamic event tables first
 511
 512         if ( m_dynamicEvents && SearchDynamicEventTable(event) )
 513             return TRUE;
 514
 515         // Then static per-class event tables
 516
 517         const wxEventTable *table = GetEventTable();
 518
 519         // Try the associated validator first, if this is a window.
 520         // Problem: if the event handler of the window has been replaced,
 521         // this wxEvtHandler may no longer be a window.
 522         // Therefore validators won't be processed if the handler
 523         // has been replaced with SetEventHandler.
 524         // THIS CAN BE CURED if PushEventHandler is used instead of
 525         // SetEventHandler, and then processing will be passed down the
 526         // chain of event handlers.
 527         if ( m_isWindow )
 528         {
 529             wxWindow *win = (wxWindow *)this;
 530
 531             // Can only use the validator of the window which
 532             // is receiving the event
 533             if ( win == event.GetEventObject() )
 534             {
 535                 wxValidator *validator = win->GetValidator();
 536                 if ( validator && validator->ProcessEvent(event) )
 537                 {
 538                     return TRUE;
 539                 }
 540             }
 541         }
 542
 543         // Search upwards through the inheritance hierarchy
 544         while ( table )
 545         {
 546             if ( SearchEventTable((wxEventTable&)*table, event) )
 547                 return TRUE;
 548             table = table->baseTable;
 549         }
 550     }
 551
 552     // Try going down the event handler chain
 553     if ( GetNextHandler() )
 554     {
 555         if ( GetNextHandler()->ProcessEvent(event) )
 556             return TRUE;
 557     }
 558
 559     // Carry on up the parent-child hierarchy,
 560     // but only if event is a command event: it wouldn't
 561     // make sense for a parent to receive a child's size event, for example
 562     if ( m_isWindow && event.IsCommandEvent() )
 563     {
 564         wxWindow *win = (wxWindow *)this;
 565         wxWindow *parent = win->GetParent();
 566         if (parent && !parent->IsBeingDeleted())
 567             return parent->GetEventHandler()->ProcessEvent(event);
 568     }
 569
 570     // Last try - application object.
 571     if ( wxTheApp && (this != wxTheApp) )
 572     {
 573         // Special case: don't pass wxEVT_IDLE to wxApp, since it'll always
 574         // swallow it. wxEVT_IDLE is sent explicitly to wxApp so it will be
 575         // processed appropriately via SearchEventTable.
 576         if ( event.GetEventType() != wxEVT_IDLE )
 577         {
 578             if ( wxTheApp->ProcessEvent(event) )
 579                 return TRUE;
 580         }
 581     }
 582
 583     return FALSE;
 584 }
 585
 586 bool wxEvtHandler::SearchEventTable(wxEventTable& table, wxEvent& event)
 587 {
 588     int i = 0;
 589     int commandId = event.GetId();
 590
 591     // BC++ doesn't like while (table.entries[i].m_fn)
 592
 593 #ifdef __SC__
 594     while (table.entries[i].m_fn != 0)
 595 #else
 596     while (table.entries[i].m_fn != 0L)
 597 #endif
 598     {
 599         if ((event.GetEventType() == table.entries[i].m_eventType) &&
 600                 (table.entries[i].m_id == -1 || // Match, if event spec says any id will do (id == -1)
 601                  (table.entries[i].m_lastId == -1 && commandId == table.entries[i].m_id) ||
 602                  (table.entries[i].m_lastId != -1 &&
 603                   (commandId >= table.entries[i].m_id && commandId <= table.entries[i].m_lastId))))
 604         {
 605             event.Skip(FALSE);
 606             event.m_callbackUserData = table.entries[i].m_callbackUserData;
 607
 608             (this->*((wxEventFunction) (table.entries[i].m_fn)))(event);
 609
 610             if ( event.GetSkipped() )
 611                 return FALSE;
 612             else
 613                 return TRUE;
 614         }
 615         i++;
 616     }
 617     return FALSE;
 618 }
 619 void wxEvtHandler::Connect( int id, int lastId,
 620                             wxEventType eventType,
 621                             wxObjectEventFunction func,
 622                             wxObject *userData )
 623 {
 624     wxEventTableEntry *entry = new wxEventTableEntry;
 625     entry->m_id = id;
 626     entry->m_lastId = lastId;
 627     entry->m_eventType = eventType;
 628     entry->m_fn = func;
 629     entry->m_callbackUserData = userData;
 630
 631     if (!m_dynamicEvents)
 632         m_dynamicEvents = new wxList;
 633
 634     m_dynamicEvents->Append( (wxObject*) entry );
 635 }
 636
 637 bool wxEvtHandler::SearchDynamicEventTable( wxEvent& event )
 638 {
 639     wxCHECK_MSG( m_dynamicEvents, FALSE,
 640                  _T("caller should check that we have dynamic events") );
 641
 642     int commandId = event.GetId();
 643
 644     wxNode *node = m_dynamicEvents->First();
 645     while (node)
 646     {
 647         wxEventTableEntry *entry = (wxEventTableEntry*)node->Data();
 648
 649         if (entry->m_fn)
 650         {
 651             // Match, if event spec says any id will do (id == -1)
 652             if ( (event.GetEventType() == entry->m_eventType) &&
 653                  (entry->m_id == -1 ||
 654                   (entry->m_lastId == -1 && commandId == entry->m_id) ||
 655                   (entry->m_lastId != -1 &&
 656                   (commandId >= entry->m_id && commandId <= entry->m_lastId))) )
 657             {
 658                 event.Skip(FALSE);
 659                 event.m_callbackUserData = entry->m_callbackUserData;
 660
 661                 (this->*((wxEventFunction) (entry->m_fn)))(event);
 662
 663                 if (event.GetSkipped())
 664                     return FALSE;
 665                 else
 666                     return TRUE;
 667             }
 668         }
 669         node = node->Next();
 670     }
 671     return FALSE;
 672 };
 673
 674 #if WXWIN_COMPATIBILITY
 675 bool wxEvtHandler::OnClose()
 676 {
 677     if (GetNextHandler())
 678         return GetNextHandler()->OnClose();
 679     else
 680         return FALSE;
 681 }
 682 #endif // WXWIN_COMPATIBILITY
 683
 684 // Find a window with the focus, that is also a descendant of the given window.
 685 // This is used to determine the window to initially send commands to.
 686 wxWindow* wxFindFocusDescendant(wxWindow* ancestor)
 687 {
 688     // Process events starting with the window with the focus, if any.
 689     wxWindow* focusWin = wxWindow::FindFocus();
 690     wxWindow* win = focusWin;
 691
 692     // Check if this is a descendant of this frame.
 693     // If not, win will be set to NULL.
 694     while (win)
 695     {
 696         if (win == ancestor)
 697             break;
 698         else
 699             win = win->GetParent();
 700     }
 701     if (win == (wxWindow*) NULL)
 702         focusWin = (wxWindow*) NULL;
 703
 704     return focusWin;
 705 }
 706