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1\section{\class{wxApp}}\label{wxapp}
2
3The {\bf wxApp} class represents the application itself. It is used
4to:
5
6\begin{itemize}\itemsep=0pt
7\item set and get application-wide properties;
8\item implement the windowing system message or event loop;
9\item initiate application processing via \helpref{wxApp::OnInit}{wxapponinit};
10\item allow default processing of events not handled by other
11objects in the application.
12\end{itemize}
13
14You should use the macro IMPLEMENT\_APP(appClass) in your application implementation
15file to tell wxWidgets how to create an instance of your application class.
16
17Use DECLARE\_APP(appClass) in a header file if you want the wxGetApp function (which returns
18a reference to your application object) to be visible to other files.
19
20\wxheading{Derived from}
21
22\helpref{wxEvtHandler}{wxevthandler}\\
23\helpref{wxObject}{wxobject}
24
25\wxheading{Include files}
26
27<wx/app.h>
28
29\wxheading{See also}
30
31\helpref{wxApp overview}{wxappoverview}
32
33\latexignore{\rtfignore{\wxheading{Members}}}
34
35
36\membersection{wxApp::wxApp}\label{wxappctor}
37
38\func{void}{wxApp}{\void}
39
40Constructor. Called implicitly with a definition of a wxApp object.
41
42
43\membersection{wxApp::\destruct{wxApp}}\label{wxappdtor}
44
45\func{void}{\destruct{wxApp}}{\void}
46
47Destructor. Will be called implicitly on program exit if the wxApp
48object is created on the stack.
49
50
51\membersection{wxApp::argc}\label{wxappargc}
52
53\member{int}{argc}
54
55Number of command line arguments (after environment-specific processing).
56
57
58\membersection{wxApp::argv}\label{wxappargv}
59
60\member{char **}{argv}
61
62Command line arguments (after environment-specific processing).
63
64
65\membersection{wxApp::CreateLogTarget}\label{wxappcreatelogtarget}
66
67\func{virtual wxLog*}{CreateLogTarget}{\void}
68
69Creates a wxLog class for the application to use for logging errors. The default
70implementation returns a new wxLogGui class.
71
72\wxheading{See also}
73
74\helpref{wxLog}{wxlog}
75
76
77\membersection{wxApp::Dispatch}\label{wxappdispatch}
78
79\func{virtual void}{Dispatch}{\void}
80
81Dispatches the next event in the windowing system event queue.
82
83This can be used for programming event loops, e.g.
84
85\begin{verbatim}
86 while (app.Pending())
87 Dispatch();
88\end{verbatim}
89
90\wxheading{See also}
91
92\helpref{wxApp::Pending}{wxapppending}
93
94
95\membersection{wxApp::ExitMainLoop}\label{wxappexitmainloop}
96
97\func{virtual void}{ExitMainLoop}{\void}
98
99Call this to explicitly exit the main message (event) loop.
100You should normally exit the main loop (and the application) by deleting
101the top window.
102
103
104\membersection{wxApp::FilterEvent}\label{wxappfilterevent}
105
106\func{int}{FilterEvent}{\param{wxEvent\& }{event}}
107
108This function is called before processing any event and allows the application
109to preempt the processing of some events. If this method returns $-1$ the event
110is processed normally, otherwise either {\tt true} or {\tt false} should be
111returned and the event processing stops immediately considering that the event
112had been already processed (for the former return value) or that it is not
113going to be processed at all (for the latter one).
114
115
116\membersection{wxApp::GetAppName}\label{wxappgetappname}
117
118\constfunc{wxString}{GetAppName}{\void}
119
120Returns the application name.
121
122\wxheading{Remarks}
123
124wxWidgets sets this to a reasonable default before
125calling \helpref{wxApp::OnInit}{wxapponinit}, but the application can reset it at will.
126
127
128\membersection{wxApp::GetClassName}\label{wxappgetclassname}
129
130\constfunc{wxString}{GetClassName}{\void}
131
132Gets the class name of the application. The class name may be used in a platform specific
133manner to refer to the application.
134
135\wxheading{See also}
136
137\helpref{wxApp::SetClassName}{wxappsetclassname}
138
139
140\membersection{wxApp::GetExitOnFrameDelete}\label{wxappgetexitonframedelete}
141
142\constfunc{bool}{GetExitOnFrameDelete}{\void}
143
144Returns true if the application will exit when the top-level window is deleted, false
145otherwise.
146
147\wxheading{See also}
148
149\helpref{wxApp::SetExitOnFrameDelete}{wxappsetexitonframedelete},\\
150\helpref{wxApp shutdown overview}{wxappshutdownoverview}
151
152
153\membersection{wxApp::GetInstance}\label{wxappgetinstance}
154
155\func{static wxAppConsole *}{GetInstance}{\void}
156
157Returns the one and only global application object.
158Usually \texttt{wxTheApp} is usead instead.
159
160\wxheading{See also}
161
162\helpref{wxApp::SetInstance}{wxappsetinstance}
163
164
165\membersection{wxApp::GetTopWindow}\label{wxappgettopwindow}
166
167\constfunc{virtual wxWindow *}{GetTopWindow}{\void}
168
169Returns a pointer to the top window.
170
171\wxheading{Remarks}
172
173If the top window hasn't been set using \helpref{wxApp::SetTopWindow}{wxappsettopwindow}, this
174function will find the first top-level window (frame or dialog) and return that.
175
176\wxheading{See also}
177
178\helpref{SetTopWindow}{wxappsettopwindow}
179
180
181\membersection{wxApp::GetUseBestVisual}\label{wxappgetusebestvisual}
182
183\constfunc{bool}{GetUseBestVisual}{\void}
184
185Returns true if the application will use the best visual on systems that support
186different visuals, false otherwise.
187
188\wxheading{See also}
189
190\helpref{SetUseBestVisual}{wxappsetusebestvisual}
191
192
193\membersection{wxApp::GetVendorName}\label{wxappgetvendorname}
194
195\constfunc{wxString}{GetVendorName}{\void}
196
197Returns the application's vendor name.
198
199
200\membersection{wxApp::IsActive}\label{wxappisactive}
201
202\constfunc{bool}{IsActive}{\void}
203
204Returns \true if the application is active, i.e. if one of its windows is
205currently in the foreground. If this function returns \false and you need to
206attract users attention to the application, you may use
207\helpref{wxTopLevelWindow::RequestUserAttention}{wxtoplevelwindowrequestuserattention}
208to do it.
209
210
211\membersection{wxApp::IsMainLoopRunning}\label{wxappismainlooprunning}
212
213\func{static bool}{IsMainLoopRunning}{\void}
214
215Returns \true if the main event loop is currently running, i.e. if the
216application is inside \helpref{OnRun}{wxapponrun}.
217
218This can be useful to test whether the events can be dispatched. For example,
219if this function returns \false, non-blocking sockets cannot be used because
220the events from them would never be processed.
221
222
223\membersection{wxApp::MainLoop}\label{wxappmainloop}
224
225\func{virtual int}{MainLoop}{\void}
226
227Called by wxWidgets on creation of the application. Override this if you wish
228to provide your own (environment-dependent) main loop.
229
230\wxheading{Return value}
231
232Returns 0 under X, and the wParam of the WM\_QUIT message under Windows.
233
234%% VZ: OnXXX() functions should *not* be documented
235%%
236%%\membersection{wxApp::OnActivate}\label{wxapponactivate}
237%%
238%%\func{void}{OnActivate}{\param{wxActivateEvent\& }{event}}
239%%
240%%Provide this member function to know whether the application is being
241%%activated or deactivated (Windows only).
242%%
243%%\wxheading{See also}
244%%
245%%\helpref{wxWindow::OnActivate}{wxwindowonactivate}, \helpref{wxActivateEvent}{wxactivateevent}
246%%
247%%\membersection{wxApp::OnCharHook}\label{wxapponcharhook}
248%%
249%%\func{void}{OnCharHook}{\param{wxKeyEvent\&}{ event}}
250%%
251%%This event handler function is called (under Windows only) to allow the window to intercept keyboard events
252%%before they are processed by child windows.
253%%
254%%\wxheading{Parameters}
255%%
256%%\docparam{event}{The keypress event.}
257%%
258%%\wxheading{Remarks}
259%%
260%%Use the wxEVT\_CHAR\_HOOK macro in your event table.
261%%
262%%If you use this member, you can selectively consume keypress events by calling\rtfsp
263%%\helpref{wxEvent::Skip}{wxeventskip} for characters the application is not interested in.
264%%
265%%\wxheading{See also}
266%%
267%%\helpref{wxKeyEvent}{wxkeyevent}, \helpref{wxWindow::OnChar}{wxwindowonchar},\rtfsp
268%%\helpref{wxWindow::OnCharHook}{wxwindowoncharhook}, \helpref{wxDialog::OnCharHook}{wxdialogoncharhook}
269
270
271\membersection{wxApp::OnAssert}\label{wxapponassert}
272
273\func{void}{OnAssert}{\param{const wxChar }{*file}, \param{int }{line}, \param{const wxChar }{*cond}, \param{const wxChar }{*msg}}
274
275This function is called when an assert failure occurs, i.e. the condition
276specified in \helpref{wxASSERT}{wxassert} macro evaluated to {\tt false}.
277It is only called in debug mode (when {\tt \_\_WXDEBUG\_\_} is defined) as
278asserts are not left in the release code at all.
279
280The base class version show the default assert failure dialog box proposing to
281the user to stop the program, continue or ignore all subsequent asserts.
282
283\wxheading{Parameters}
284
285\docparam{file}{the name of the source file where the assert occured}
286
287\docparam{line}{the line number in this file where the assert occured}
288
289\docparam{cond}{the condition of the failed assert in string form}
290
291\docparam{msg}{the message specified as argument to
292\helpref{wxASSERT\_MSG}{wxassertmsg} or \helpref{wxFAIL\_MSG}{wxfailmsg}, will
293be {\tt NULL} if just \helpref{wxASSERT}{wxassert} or \helpref{wxFAIL}{wxfail}
294was used}
295
296
297\membersection{wxApp::OnCmdLineError}\label{wxapponcmdlineerror}
298
299\func{bool}{OnCmdLineError}{\param{wxCmdLineParser\& }{parser}}
300
301Called when command line parsing fails (i.e. an incorrect command line option
302was specified by the user). The default behaviour is to show the program usage
303text and abort the program.
304
305Return {\tt true} to continue normal execution or {\tt false} to return
306{\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program.
307
308\wxheading{See also}
309
310\helpref{OnInitCmdLine}{wxapponinitcmdline}
311
312
313\membersection{wxApp::OnCmdLineHelp}\label{wxapponcmdlinehelp}
314
315\func{bool}{OnCmdLineHelp}{\param{wxCmdLineParser\& }{parser}}
316
317Called when the help option ({\tt --help}) was specified on the command line.
318The default behaviour is to show the program usage text and abort the program.
319
320Return {\tt true} to continue normal execution or {\tt false} to return
321{\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program.
322
323\wxheading{See also}
324
325\helpref{OnInitCmdLine}{wxapponinitcmdline}
326
327
328\membersection{wxApp::OnCmdLineParsed}\label{wxapponcmdlineparsed}
329
330\func{bool}{OnCmdLineParsed}{\param{wxCmdLineParser\& }{parser}}
331
332Called after the command line had been successfully parsed. You may override
333this method to test for the values of the various parameters which could be
334set from the command line.
335
336Don't forget to call the base class version unless you want to suppress
337processing of the standard command line options.
338
339Return {\tt true} to continue normal execution or {\tt false} to return
340{\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program.
341
342\wxheading{See also}
343
344\helpref{OnInitCmdLine}{wxapponinitcmdline}
345
346
347\membersection{wxApp::OnExceptionInMainLoop}\label{wxapponexceptioninmainloop}
348
349\func{virtual bool}{OnExceptionInMainLoop}{\void}
350
351This function is called if an unhandled exception occurs inside the main
352application event loop. It can return \true to ignore the exception and to
353continue running the loop or \false to exit the loop and terminate the
354program. In the latter case it can also use C++ \texttt{throw} keyword to
355rethrow the current exception.
356
357The default behaviour of this function is the latter in all ports except under
358Windows where a dialog is shown to the user which allows him to choose between
359the different options. You may override this function in your class to do
360something more appropriate.
361
362Finally note that if the exception is rethrown from here, it can be caught in
363\helpref{OnUnhandledException}{wxapponunhandledexception}.
364
365
366\membersection{wxApp::OnExit}\label{wxapponexit}
367
368\func{virtual int}{OnExit}{\void}
369
370Override this member function for any processing which needs to be
371done as the application is about to exit. OnExit is called after
372destroying all application windows and controls, but before
373wxWidgets cleanup. Note that it is not called at all if
374\helpref{OnInit}{wxapponinit} failed.
375
376The return value of this function is currently ignored, return the same value
377as returned by the base class method if you override it.
378
379
380\membersection{wxApp::OnFatalException}\label{wxapponfatalexception}
381
382\func{void}{OnFatalException}{\void}
383
384This function may be called if something fatal happens: an unhandled
385exception under Win32 or a a fatal signal under Unix, for example. However,
386this will not happen by default: you have to explicitly call
387\helpref{wxHandleFatalExceptions}{wxhandlefatalexceptions} to enable this.
388
389Generally speaking, this function should only show a message to the user and
390return. You may attempt to save unsaved data but this is not guaranteed to
391work and, in fact, probably won't.
392
393\wxheading{See also}
394
395\helpref{wxHandleFatalExceptions}{wxhandlefatalexceptions}
396
397%% VZ: the wxApp event handler are private and should not be documented here!
398%%
399%%\membersection{wxApp::OnIdle}\label{wxapponidle}
400%%
401%%\func{void}{OnIdle}{\param{wxIdleEvent\& }{event}}
402%%
403%%Override this member function for any processing which needs to be done
404%%when the application is idle. You should call wxApp::OnIdle from your own function,
405%%since this forwards OnIdle events to windows and also performs garbage collection for
406%%windows whose destruction has been delayed.
407%%
408%%wxWidgets' strategy for OnIdle processing is as follows. After pending user interface events for an
409%%application have all been processed, wxWidgets sends an OnIdle event to the application object. wxApp::OnIdle itself
410%%sends an OnIdle event to each application window, allowing windows to do idle processing such as updating
411%%their appearance. If either wxApp::OnIdle or a window OnIdle function requested more time, by
412%%calling \helpref{wxIdleEvent::RequestMore}{wxidleeventrequestmore}, wxWidgets will send another OnIdle
413%%event to the application object. This will occur in a loop until either a user event is found to be
414%%pending, or OnIdle requests no more time. Then all pending user events are processed until the system
415%%goes idle again, when OnIdle is called, and so on.
416%%
417%%\wxheading{See also}
418%%
419%%\helpref{wxWindow::OnIdle}{wxwindowonidle}, \helpref{wxIdleEvent}{wxidleevent},\rtfsp
420%%\helpref{wxWindow::SendIdleEvents}{wxappsendidleevents}
421%%
422%%\membersection{wxApp::OnEndSession}\label{wxapponendsession}
423%%
424%%\func{void}{OnEndSession}{\param{wxCloseEvent\& }{event}}
425%%
426%%This is an event handler function called when the operating system or GUI session is
427%%about to close down. The application has a chance to silently save information,
428%%and can optionally close itself.
429%%
430%%Use the EVT\_END\_SESSION event table macro to handle query end session events.
431%%
432%%The default handler calls \helpref{wxWindow::Close}{wxwindowclose} with a true argument
433%%(forcing the application to close itself silently).
434%%
435%%\wxheading{Remarks}
436%%
437%%Under X, OnEndSession is called in response to the `die' event.
438%%
439%%Under Windows, OnEndSession is called in response to the WM\_ENDSESSION message.
440%%
441%%\wxheading{See also}
442%%
443%%\helpref{wxWindow::Close}{wxwindowclose},\rtfsp
444%%\helpref{wxWindow::OnCloseWindow}{wxwindowonclosewindow},\rtfsp
445%%\helpref{wxCloseEvent}{wxcloseevent},\rtfsp
446%%\helpref{wxApp::OnQueryEndSession}{wxapponqueryendsession}
447
448
449\membersection{wxApp::OnInit}\label{wxapponinit}
450
451\func{bool}{OnInit}{\void}
452
453This must be provided by the application, and will usually create the
454application's main window, optionally calling
455\helpref{wxApp::SetTopWindow}{wxappsettopwindow}. You may use
456\helpref{OnExit}{wxapponexit} to clean up anything initialized here, provided
457that the function returns \true.
458
459Notice that if you want to to use the command line processing provided by
460wxWidgets you have to call the base class version in the derived class
461OnInit().
462
463Return \true to continue processing, \false to exit the application
464immediately.
465
466
467\membersection{wxApp::OnInitCmdLine}\label{wxapponinitcmdline}
468
469\func{void}{OnInitCmdLine}{\param{wxCmdLineParser\& }{parser}}
470
471Called from \helpref{OnInit}{wxapponinit} and may be used to initialize the
472parser with the command line options for this application. The base class
473versions adds support for a few standard options only.
474
475
476\membersection{wxApp::OnQueryEndSession}\label{wxapponqueryendsession}
477
478\func{void}{OnQueryEndSession}{\param{wxCloseEvent\& }{event}}
479
480This is an event handler function called when the operating system or GUI session is
481about to close down. Typically, an application will try to save unsaved documents
482at this point.
483
484If \helpref{wxCloseEvent::CanVeto}{wxcloseeventcanveto} returns true, the application
485is allowed to veto the shutdown by calling \helpref{wxCloseEvent::Veto}{wxcloseeventveto}.
486The application might veto the shutdown after prompting for documents to be saved, and the
487user has cancelled the save.
488
489Use the EVT\_QUERY\_END\_SESSION event table macro to handle query end session events.
490
491You should check whether the application is forcing the deletion of the window
492using \helpref{wxCloseEvent::GetForce}{wxcloseeventgetforce}. If this is true,
493destroy the window using \helpref{wxWindow::Destroy}{wxwindowdestroy}.
494If not, it is up to you whether you respond by destroying the window.
495
496The default handler calls \helpref{wxWindow::Close}{wxwindowclose} on the top-level window,
497and vetoes the shutdown if Close returns false. This will be sufficient for many applications.
498
499\wxheading{Remarks}
500
501Under X, OnQueryEndSession is called in response to the `save session' event.
502
503Under Windows, OnQueryEndSession is called in response to the WM\_QUERYENDSESSION message.
504
505\wxheading{See also}
506
507\helpref{wxWindow::Close}{wxwindowclose},\rtfsp
508\helpref{wxCloseEvent}{wxcloseevent}\rtfsp
509
510
511\membersection{wxApp::OnRun}\label{wxapponrun}
512
513\func{virtual int}{OnRun}{\void}
514
515This virtual function is where the execution of a program written in wxWidgets
516starts. The default implementation just enters the main loop and starts
517handling the events until it terminates, either because
518\helpref{ExitMainLoop}{wxappexitmainloop} has been explicitly called or because
519the last frame has been deleted and
520\helpref{GetExitOnFrameDelete}{wxappgetexitonframedelete} flag is \true (this
521is the default).
522
523The return value of this function becomes the exit code of the program, so it
524should return $0$ in case of successful termination.
525
526
527\membersection{wxApp::OnUnhandledException}\label{wxapponunhandledexception}
528
529\func{virtual void}{OnUnhandledException}{\void}
530
531This function is called when an unhandled C++ exception occurs inside
532\helpref{OnRun()}{wxapponrun} (the exceptions which occur during the program
533startup and shutdown might not be caught at all).
534Note that the exception type is lost by now, so if you want to really handle
535the exception you should override \helpref{OnRun()}{wxapponrun} and put a
536try/catch clause around the call to the base class version there.
537
538
539\membersection{wxApp::ProcessMessage}\label{wxappprocessmessage}
540
541\func{bool}{ProcessMessage}{\param{WXMSG *}{msg}}
542
543Windows-only function for processing a message. This function
544is called from the main message loop, checking for windows that
545may wish to process it. The function returns true if the message
546was processed, false otherwise. If you use wxWidgets with another class
547library with its own message loop, you should make sure that this
548function is called to allow wxWidgets to receive messages. For example,
549to allow co-existence with the Microsoft Foundation Classes, override
550the PreTranslateMessage function:
551
552\begin{verbatim}
553// Provide wxWidgets message loop compatibility
554BOOL CTheApp::PreTranslateMessage(MSG *msg)
555{
556 if (wxTheApp && wxTheApp->ProcessMessage((WXMSW *)msg))
557 return true;
558 else
559 return CWinApp::PreTranslateMessage(msg);
560}
561\end{verbatim}
562
563
564\membersection{wxApp::Pending}\label{wxapppending}
565
566\func{virtual bool}{Pending}{\void}
567
568Returns true if unprocessed events are in the window system event queue.
569
570\wxheading{See also}
571
572\helpref{wxApp::Dispatch}{wxappdispatch}
573
574
575\membersection{wxApp::SendIdleEvents}\label{wxappsendidleevents}
576
577\func{bool}{SendIdleEvents}{\param{wxWindow*}{ win}, \param{wxIdleEvent\& }{event}}
578
579Sends idle events to a window and its children.
580
581Please note that this function is internal to wxWidgets and shouldn't be used
582by user code.
583
584\wxheading{Remarks}
585
586These functions poll the top-level windows, and their children, for idle event processing.
587If true is returned, more OnIdle processing is requested by one or more window.
588
589\wxheading{See also}
590
591\helpref{wxIdleEvent}{wxidleevent}
592
593
594\membersection{wxApp::SetAppName}\label{wxappsetappname}
595
596\func{void}{SetAppName}{\param{const wxString\& }{name}}
597
598Sets the name of the application. The name may be used in dialogs
599(for example by the document/view framework). A default name is set by
600wxWidgets.
601
602\wxheading{See also}
603
604\helpref{wxApp::GetAppName}{wxappgetappname}
605
606
607\membersection{wxApp::SetClassName}\label{wxappsetclassname}
608
609\func{void}{SetClassName}{\param{const wxString\& }{name}}
610
611Sets the class name of the application. This may be used in a platform specific
612manner to refer to the application.
613
614\wxheading{See also}
615
616\helpref{wxApp::GetClassName}{wxappgetclassname}
617
618
619\membersection{wxApp::SetExitOnFrameDelete}\label{wxappsetexitonframedelete}
620
621\func{void}{SetExitOnFrameDelete}{\param{bool}{ flag}}
622
623Allows the programmer to specify whether the application will exit when the
624top-level frame is deleted.
625
626\wxheading{Parameters}
627
628\docparam{flag}{If true (the default), the application will exit when the top-level frame is
629deleted. If false, the application will continue to run.}
630
631\wxheading{See also}
632
633\helpref{wxApp::GetExitOnFrameDelete}{wxappgetexitonframedelete},\\
634\helpref{wxApp shutdown overview}{wxappshutdownoverview}
635
636
637\membersection{wxApp::SetInstance}\label{wxappsetinstance}
638
639\func{static void}{SetInstance}{\param{wxAppConsole* }{app}}
640
641Allows external code to modify global \texttt{wxTheApp}, but you should really
642know what you're doing if you call it.
643
644\wxheading{Parameters}
645
646\docparam{app}{Replacement for the global application object.}
647
648\wxheading{See also}
649
650\helpref{wxApp::GetInstance}{wxappgetinstance}
651
652
653\membersection{wxApp::SetTopWindow}\label{wxappsettopwindow}
654
655\func{void}{SetTopWindow}{\param{wxWindow* }{window}}
656
657Sets the `top' window. You can call this from within \helpref{wxApp::OnInit}{wxapponinit} to
658let wxWidgets know which is the main window. You don't have to set the top window;
659it is only a convenience so that (for example) certain dialogs without parents can use a
660specific window as the top window. If no top window is specified by the application,
661wxWidgets just uses the first frame or dialog in its top-level window list, when it
662needs to use the top window.
663
664\wxheading{Parameters}
665
666\docparam{window}{The new top window.}
667
668\wxheading{See also}
669
670\helpref{wxApp::GetTopWindow}{wxappgettopwindow}, \helpref{wxApp::OnInit}{wxapponinit}
671
672
673
674\membersection{wxApp::SetVendorName}\label{wxappsetvendorname}
675
676\func{void}{SetVendorName}{\param{const wxString\& }{name}}
677
678Sets the name of application's vendor. The name will be used
679in registry access. A default name is set by
680wxWidgets.
681
682\wxheading{See also}
683
684\helpref{wxApp::GetVendorName}{wxappgetvendorname}
685
686
687\membersection{wxApp::SetUseBestVisual}\label{wxappsetusebestvisual}
688
689\func{void}{SetUseBestVisual}{\param{bool}{ flag}}
690
691Allows the programmer to specify whether the application will use the best visual
692on systems that support several visual on the same display. This is typically the
693case under Solaris and IRIX, where the default visual is only 8-bit whereas certain
694applications are supposed to run in TrueColour mode.
695
696Note that this function has to be called in the constructor of the {\tt wxApp}
697instance and won't have any effect when called later on.
698
699This function currently only has effect under GTK.
700
701\wxheading{Parameters}
702
703\docparam{flag}{If true, the app will use the best visual.}
704
705
706\membersection{wxApp::HandleEvent}\label{wxapphandleevent}
707
708\constfunc{virtual void}{HandleEvent}{\param{wxEvtHandler}{ *handler}, \param{wxEventFunction}{ func}, \param{wxEvent\& }{event}}
709
710This function simply invokes the given method \arg{func} of the specified
711event handler \arg{handler} with the \arg{event} as parameter. It exists solely
712to allow to catch the C++ exceptions which could be thrown by all event
713handlers in the application in one place: if you want to do this, override this
714function in your wxApp-derived class and add try/catch clause(s) to it.
715
716
717\membersection{wxApp::Yield}\label{wxappyield}
718
719\func{bool}{Yield}{\param{bool}{ onlyIfNeeded = false}}
720
721Yields control to pending messages in the windowing system. This can be useful, for example, when a
722time-consuming process writes to a text window. Without an occasional
723yield, the text window will not be updated properly, and on systems with
724cooperative multitasking, such as Windows 3.1 other processes will not respond.
725
726Caution should be exercised, however, since yielding may allow the
727user to perform actions which are not compatible with the current task.
728Disabling menu items or whole menus during processing can avoid unwanted
729reentrance of code: see \helpref{::wxSafeYield}{wxsafeyield} for a better
730function.
731
732Note that Yield() will not flush the message logs. This is intentional as
733calling Yield() is usually done to quickly update the screen and popping up a
734message box dialog may be undesirable. If you do wish to flush the log
735messages immediately (otherwise it will be done during the next idle loop
736iteration), call \helpref{wxLog::FlushActive}{wxlogflushactive}.
737
738Calling Yield() recursively is normally an error and an assert failure is
739raised in debug build if such situation is detected. However if the the
740{\it onlyIfNeeded} parameter is {\tt true}, the method will just silently
741return {\tt false} instead.
742