interface/app.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        app.h
   3 // Purpose:     documentation for wxApp class
   4 // Author:      wxWidgets team
   5 // RCS-ID:      $Id$
   6 // Licence:     wxWindows license
   7 /////////////////////////////////////////////////////////////////////////////
   8
   9 /**
  10     @class wxApp
  11     @wxheader{app.h}
  12
  13     The @b wxApp class represents the application itself. It is used
  14     to:
  15
  16      set and get application-wide properties;
  17      implement the windowing system message or event loop;
  18      initiate application processing via wxApp::OnInit;
  19      allow default processing of events not handled by other
  20     objects in the application.
  21
  22     You should use the macro IMPLEMENT_APP(appClass) in your application
  23     implementation
  24     file to tell wxWidgets how to create an instance of your application class.
  25
  26     Use DECLARE_APP(appClass) in a header file if you want the wxGetApp function
  27     (which returns
  28     a reference to your application object) to be visible to other files.
  29
  30     @library{wxbase}
  31     @category{appmanagement}
  32
  33     @seealso
  34     @ref overview_wxappoverview "wxApp overview"
  35 */
  36 class wxApp : public wxEvtHandler
  37 {
  38 public:
  39     /**
  40         Constructor. Called implicitly with a definition of a wxApp object.
  41     */
  42     wxApp();
  43
  44     /**
  45         Destructor. Will be called implicitly on program exit if the wxApp
  46         object is created on the stack.
  47     */
  48     ~wxApp();
  49
  50     /**
  51         Creates a wxLog class for the application to use for logging errors. The default
  52         implementation returns a new wxLogGui class.
  53
  54         @sa wxLog
  55     */
  56     virtual wxLog* CreateLogTarget();
  57
  58     /**
  59         Creates the wxAppTraits object when GetTraits()
  60         needs it for the first time.
  61
  62         @sa wxAppTraits
  63     */
  64     virtual wxAppTraits * CreateTraits();
  65
  66     /**
  67         Dispatches the next event in the windowing system event queue.
  68
  69         This can be used for programming event loops, e.g.
  70
  71         @sa Pending()
  72     */
  73     virtual void Dispatch();
  74
  75     /**
  76         Call this to explicitly exit the main message (event) loop.
  77         You should normally exit the main loop (and the application) by deleting
  78         the top window.
  79     */
  80     virtual void ExitMainLoop();
  81
  82     /**
  83         This function is called before processing any event and allows the application
  84         to preempt the processing of some events. If this method returns -1 the event
  85         is processed normally, otherwise either @true or @false should be
  86         returned and the event processing stops immediately considering that the event
  87         had been already processed (for the former return value) or that it is not
  88         going to be processed at all (for the latter one).
  89     */
  90     int FilterEvent(wxEvent& event);
  91
  92     /**
  93         Returns the user-readable application name. The difference between this string
  94         and the one returned by GetAppName() is that this one
  95         is meant to be shown to the user and so should be used for the window titles,
  96         page headers and so on while the other one should be only used internally, e.g.
  97         for the file names or configuration file keys.
  98
  99         By default, returns the same string as GetAppName().
 100
 101         This function is new since wxWidgets version 2.9.0
 102     */
 103     wxString GetAppDisplayName();
 104
 105     /**
 106         Returns the application name.
 107
 108         @remarks wxWidgets sets this to a reasonable default before calling
 109                    OnInit(), but the application can reset it at
 110                    will.
 111
 112         @sa GetAppDisplayName()
 113     */
 114     wxString GetAppName();
 115
 116     /**
 117         Gets the class name of the application. The class name may be used in a
 118         platform specific
 119         manner to refer to the application.
 120
 121         @sa SetClassName()
 122     */
 123     wxString GetClassName();
 124
 125     /**
 126         Returns @true if the application will exit when the top-level window is deleted,
 127         @false
 128         otherwise.
 129
 130         @sa SetExitOnFrameDelete(), @ref overview_wxappshutdownoverview "wxApp
 131               shutdown overview"
 132     */
 133     bool GetExitOnFrameDelete();
 134
 135     /**
 136         Returns the one and only global application object.
 137         Usually @c wxTheApp is usead instead.
 138
 139         @sa SetInstance()
 140     */
 141     static wxAppConsole * GetInstance();
 142
 143     /**
 144         Returns a pointer to the top window.
 145
 146         @remarks If the top window hasn't been set using SetTopWindow(),
 147                    this function will find the first top-level window
 148                    (frame or dialog) and return that.
 149
 150         @sa SetTopWindow()
 151     */
 152     virtual wxWindow * GetTopWindow();
 153
 154     /**
 155         Returns a pointer to the wxAppTraits object for the application.
 156         If you want to customize the wxAppTraits object, you must override the
 157         CreateTraits() function.
 158     */
 159     wxAppTraits * GetTraits();
 160
 161     /**
 162         Returns @true if the application will use the best visual on systems that support
 163         different visuals, @false otherwise.
 164
 165         @sa SetUseBestVisual()
 166     */
 167     bool GetUseBestVisual();
 168
 169     /**
 170         Returns the user-readable vendor name. The difference between this string
 171         and the one returned by GetVendorName() is that this one
 172         is meant to be shown to the user and so should be used for the window titles,
 173         page headers and so on while the other one should be only used internally, e.g.
 174         for the file names or configuration file keys.
 175
 176         By default, returns the same string as GetVendorName().
 177
 178         This function is new since wxWidgets version 2.9.0
 179     */
 180     wxString GetVendorDisplayName();
 181
 182     /**
 183         Returns the application's vendor name.
 184     */
 185     wxString GetVendorName();
 186
 187     /**
 188         This function simply invokes the given method @e func of the specified
 189         event handler @e handler with the @e event as parameter. It exists solely
 190         to allow to catch the C++ exceptions which could be thrown by all event
 191         handlers in the application in one place: if you want to do this, override this
 192         function in your wxApp-derived class and add try/catch clause(s) to it.
 193     */
 194     virtual void HandleEvent(wxEvtHandler handler,
 195                              wxEventFunction func,
 196                              wxEvent& event);
 197
 198     /**
 199         Returns @true if the application is active, i.e. if one of its windows is
 200         currently in the foreground. If this function returns @false and you need to
 201         attract users attention to the application, you may use
 202         wxTopLevelWindow::RequestUserAttention
 203         to do it.
 204     */
 205     bool IsActive();
 206
 207     /**
 208         Returns @true if the main event loop is currently running, i.e. if the
 209         application is inside OnRun().
 210
 211         This can be useful to test whether events can be dispatched. For example,
 212         if this function returns @false, non-blocking sockets cannot be used because
 213         the events from them would never be processed.
 214     */
 215     static bool IsMainLoopRunning();
 216
 217     /**
 218         Mac specific. Called in response of an "open-application" Apple event.
 219         Override this to create a new document in your app.
 220     */
 221     void MacNewFile();
 222
 223     /**
 224         Mac specific. Called in response of an "open-document" Apple event. You need to
 225         override this method in order to open a document file after the
 226         user double clicked on it or if the document file was dropped
 227         on either the running application or the application icon in
 228         Finder.
 229     */
 230     void MacOpenFile(const wxString& fileName);
 231
 232     /**
 233         Mac specific. Called in response of a "get-url" Apple event.
 234     */
 235     void MacOpenURL(const wxString& url);
 236
 237     /**
 238         Mac specific. Called in response of a "print-document" Apple event.
 239     */
 240     void MacPrintFile(const wxString& fileName);
 241
 242     /**
 243         Mac specific. Called in response of a "reopen-application" Apple event.
 244     */
 245     void MacReopenApp();
 246
 247     /**
 248         Called by wxWidgets on creation of the application. Override this if you wish
 249         to provide your own (environment-dependent) main loop.
 250
 251         @returns Returns 0 under X, and the wParam of the WM_QUIT message under
 252                    Windows.
 253     */
 254     virtual int MainLoop();
 255
 256     /**
 257         This function is called when an assert failure occurs, i.e. the condition
 258         specified in wxASSERT macro evaluated to @false.
 259         It is only called in debug mode (when @c __WXDEBUG__ is defined) as
 260         asserts are not left in the release code at all.
 261
 262         The base class version shows the default assert failure dialog box proposing to
 263         the user to stop the program, continue or ignore all subsequent asserts.
 264
 265         @param file
 266         the name of the source file where the assert occurred
 267
 268         @param line
 269         the line number in this file where the assert occurred
 270
 271         @param func
 272         the name of the function where the assert occurred, may be
 273         empty if the compiler doesn't support C99 __FUNCTION__
 274
 275         @param cond
 276         the condition of the failed assert in text form
 277
 278         @param msg
 279         the message specified as argument to
 280         wxASSERT_MSG or wxFAIL_MSG, will
 281         be @NULL if just wxASSERT or wxFAIL
 282         was used
 283     */
 284     void OnAssertFailure(const wxChar file, int line,
 285                          const wxChar func,
 286                          const wxChar cond,
 287                          const wxChar msg);
 288
 289     /**
 290         Called when command line parsing fails (i.e. an incorrect command line option
 291         was specified by the user). The default behaviour is to show the program usage
 292         text and abort the program.
 293
 294         Return @true to continue normal execution or @false to return
 295         @false from OnInit() thus terminating the program.
 296
 297         @sa OnInitCmdLine()
 298     */
 299     bool OnCmdLineError(wxCmdLineParser& parser);
 300
 301     /**
 302         Called when the help option (@c --help) was specified on the command line.
 303         The default behaviour is to show the program usage text and abort the program.
 304
 305         Return @true to continue normal execution or @false to return
 306         @false from OnInit() thus terminating the program.
 307
 308         @sa OnInitCmdLine()
 309     */
 310     bool OnCmdLineHelp(wxCmdLineParser& parser);
 311
 312     /**
 313         Called after the command line had been successfully parsed. You may override
 314         this method to test for the values of the various parameters which could be
 315         set from the command line.
 316
 317         Don't forget to call the base class version unless you want to suppress
 318         processing of the standard command line options.
 319
 320         Return @true to continue normal execution or @false to return
 321         @false from OnInit() thus terminating the program.
 322
 323         @sa OnInitCmdLine()
 324     */
 325     bool OnCmdLineParsed(wxCmdLineParser& parser);
 326
 327     /**
 328         This function is called if an unhandled exception occurs inside the main
 329         application event loop. It can return @true to ignore the exception and to
 330         continue running the loop or @false to exit the loop and terminate the
 331         program. In the latter case it can also use C++ @c throw keyword to
 332         rethrow the current exception.
 333
 334         The default behaviour of this function is the latter in all ports except under
 335         Windows where a dialog is shown to the user which allows him to choose between
 336         the different options. You may override this function in your class to do
 337         something more appropriate.
 338
 339         Finally note that if the exception is rethrown from here, it can be caught in
 340         OnUnhandledException().
 341     */
 342     virtual bool OnExceptionInMainLoop();
 343
 344     /**
 345         Override this member function for any processing which needs to be
 346         done as the application is about to exit. OnExit is called after
 347         destroying all application windows and controls, but before
 348         wxWidgets cleanup. Note that it is not called at all if
 349         OnInit() failed.
 350
 351         The return value of this function is currently ignored, return the same value
 352         as returned by the base class method if you override it.
 353     */
 354     virtual int OnExit();
 355
 356     /**
 357         This function may be called if something fatal happens: an unhandled
 358         exception under Win32 or a a fatal signal under Unix, for example. However,
 359         this will not happen by default: you have to explicitly call
 360         wxHandleFatalExceptions to enable this.
 361
 362         Generally speaking, this function should only show a message to the user and
 363         return. You may attempt to save unsaved data but this is not guaranteed to
 364         work and, in fact, probably won't.
 365
 366         @sa wxHandleFatalExceptions
 367     */
 368     void OnFatalException();
 369
 370     /**
 371         This must be provided by the application, and will usually create the
 372         application's main window, optionally calling
 373         SetTopWindow(). You may use
 374         OnExit() to clean up anything initialized here, provided
 375         that the function returns @true.
 376
 377         Notice that if you want to to use the command line processing provided by
 378         wxWidgets you have to call the base class version in the derived class
 379         OnInit().
 380
 381         Return @true to continue processing, @false to exit the application
 382         immediately.
 383     */
 384     bool OnInit();
 385
 386     /**
 387         Called from OnInit() and may be used to initialize the
 388         parser with the command line options for this application. The base class
 389         versions adds support for a few standard options only.
 390     */
 391     void OnInitCmdLine(wxCmdLineParser& parser);
 392
 393     /**
 394         This virtual function is where the execution of a program written in wxWidgets
 395         starts. The default implementation just enters the main loop and starts
 396         handling the events until it terminates, either because
 397         ExitMainLoop() has been explicitly called or because
 398         the last frame has been deleted and
 399         GetExitOnFrameDelete() flag is @true (this
 400         is the default).
 401
 402         The return value of this function becomes the exit code of the program, so it
 403         should return 0 in case of successful termination.
 404     */
 405     virtual int OnRun();
 406
 407     /**
 408         This function is called when an unhandled C++ exception occurs inside
 409         OnRun() (the exceptions which occur during the program
 410         startup and shutdown might not be caught at all). Notice that by now the main
 411         event loop has been terminated and the program will exit, if you want to
 412         prevent this from happening (i.e. continue running after catching an exception)
 413         you need to override OnExceptionInMainLoop().
 414
 415         The default implementation shows information about the exception in debug build
 416         but does nothing in the release build.
 417     */
 418     virtual void OnUnhandledException();
 419
 420     /**
 421         Returns @true if unprocessed events are in the window system event queue.
 422
 423         @sa Dispatch()
 424     */
 425     virtual bool Pending();
 426
 427     /**
 428         Windows-only function for processing a message. This function
 429         is called from the main message loop, checking for windows that
 430         may wish to process it. The function returns @true if the message
 431         was processed, @false otherwise. If you use wxWidgets with another class
 432         library with its own message loop, you should make sure that this
 433         function is called to allow wxWidgets to receive messages. For example,
 434         to allow co-existence with the Microsoft Foundation Classes, override
 435         the PreTranslateMessage function:
 436     */
 437     bool ProcessMessage(WXMSG * msg);
 438
 439     /**
 440         Sends idle events to a window and its children.
 441
 442         Please note that this function is internal to wxWidgets and shouldn't be used
 443         by user code.
 444
 445         @remarks These functions poll the top-level windows, and their children,
 446                    for idle event processing. If @true is returned, more
 447                    OnIdle processing is requested by one or more window.
 448
 449         @sa wxIdleEvent
 450     */
 451     bool SendIdleEvents(wxWindow* win, wxIdleEvent& event);
 452
 453     /**
 454         Set the application name to be used in the user-visible places such as window
 455         titles. See GetAppDisplayName() for more about
 456         the differences between the display name and name.
 457     */
 458     void SetAppDisplayName(const wxString& name);
 459
 460     /**
 461         Sets the name of the application. This name should be used for file names,
 462         configuration file entries and other internal strings. For the user-visible
 463         strings, such as the window titles, the application display name set by
 464         SetAppDisplayName() is used instead.
 465
 466         By default the application name is set to the name of its executable file.
 467
 468         @sa GetAppName()
 469     */
 470     void SetAppName(const wxString& name);
 471
 472     /**
 473         Sets the class name of the application. This may be used in a platform specific
 474         manner to refer to the application.
 475
 476         @sa GetClassName()
 477     */
 478     void SetClassName(const wxString& name);
 479
 480     /**
 481         Allows the programmer to specify whether the application will exit when the
 482         top-level frame is deleted.
 483
 484         @param flag
 485         If @true (the default), the application will exit when the top-level frame is
 486         deleted. If @false, the application will continue to run.
 487
 488         @sa GetExitOnFrameDelete(), @ref overview_wxappshutdownoverview "wxApp
 489               shutdown overview"
 490     */
 491     void SetExitOnFrameDelete(bool flag);
 492
 493     /**
 494         Allows external code to modify global @c wxTheApp, but you should really
 495         know what you're doing if you call it.
 496
 497         @param app
 498         Replacement for the global application object.
 499
 500         @sa GetInstance()
 501     */
 502     static void SetInstance(wxAppConsole* app);
 503
 504     /**
 505         Allows runtime switching of the UI environment theme. Currently implemented for
 506         wxGTK2-only.
 507
 508         Return @true if theme was successfully changed.
 509
 510         @param theme
 511         The name of the new theme or an absolute path to a gtkrc-theme-file
 512     */
 513     bool SetNativeTheme();
 514
 515     /**
 516         Sets the 'top' window. You can call this from within OnInit() to
 517         let wxWidgets know which is the main window. You don't have to set the top
 518         window;
 519         it is only a convenience so that (for example) certain dialogs without parents
 520         can use a
 521         specific window as the top window. If no top window is specified by the
 522         application,
 523         wxWidgets just uses the first frame or dialog in its top-level window list,
 524         when it
 525         needs to use the top window.
 526
 527         @param window
 528         The new top window.
 529
 530         @sa GetTopWindow(), OnInit()
 531     */
 532     void SetTopWindow(wxWindow* window);
 533
 534     /**
 535         Allows the programmer to specify whether the application will use the best
 536         visual
 537         on systems that support several visual on the same display. This is typically
 538         the
 539         case under Solaris and IRIX, where the default visual is only 8-bit whereas
 540         certain
 541         applications are supposed to run in TrueColour mode.
 542
 543         If @e forceTrueColour is @true then the application will try to force
 544         using a TrueColour visual and abort the app if none is found.
 545
 546         Note that this function has to be called in the constructor of the @c wxApp
 547         instance and won't have any effect when called later on.
 548
 549         This function currently only has effect under GTK.
 550
 551         @param flag
 552         If @true, the app will use the best visual.
 553     */
 554     void SetUseBestVisual(bool flag, bool forceTrueColour = @false);
 555
 556     /**
 557         Set the vendor name to be used in the user-visible places. See
 558         GetVendorDisplayName() for more about
 559         the differences between the display name and name.
 560     */
 561     void SetVendorDisplayName(const wxString& name);
 562
 563     /**
 564         Sets the name of application's vendor. The name will be used
 565         in registry access. A default name is set by
 566         wxWidgets.
 567
 568         @sa GetVendorName()
 569     */
 570     void SetVendorName(const wxString& name);
 571
 572     /**
 573         Yields control to pending messages in the windowing system. This can be useful,
 574         for example, when a
 575         time-consuming process writes to a text window. Without an occasional
 576         yield, the text window will not be updated properly, and on systems with
 577         cooperative multitasking, such as Windows 3.1 other processes will not respond.
 578
 579         Caution should be exercised, however, since yielding may allow the
 580         user to perform actions which are not compatible with the current task.
 581         Disabling menu items or whole menus during processing can avoid unwanted
 582         reentrance of code: see ::wxSafeYield for a better
 583         function.
 584
 585         Note that Yield() will not flush the message logs. This is intentional as
 586         calling Yield() is usually done to quickly update the screen and popping up a
 587         message box dialog may be undesirable. If you do wish to flush the log
 588         messages immediately (otherwise it will be done during the next idle loop
 589         iteration), call wxLog::FlushActive.
 590
 591         Calling Yield() recursively is normally an error and an assert failure is
 592         raised in debug build if such situation is detected. However if the
 593         @e onlyIfNeeded parameter is @true, the method will just silently
 594         return @false instead.
 595     */
 596     bool Yield(bool onlyIfNeeded = @false);
 597
 598     /**
 599         int argc
 600
 601         Number of command line arguments (after environment-specific processing).
 602     */
 603
 604
 605     /**
 606         wxChar ** argv
 607
 608         Command line arguments (after environment-specific processing).
 609         Under Windows and Linux/Unix, you should parse the command line
 610         arguments and check for files to be opened when starting your
 611         application. Under OS X, you need to override MacOpenFile()
 612         since command line arguments are used differently there.
 613
 614         You may use the wxCmdLineParser to
 615         parse command line arguments.
 616     */
 617 };
 618
 619
 620 // ============================================================================
 621 // Global functions/macros
 622 // ============================================================================
 623
 624 //@{
 625 /**
 626     For all normal, informational messages. They also appear in a message box by
 627     default (but it can be changed).
 628 */
 629 void wxLogMessage(const char * formatString, ... );
 630 void wxVLogMessage(const char * formatString, va_list argPtr);
 631 //@}
 632
 633 //@{
 634 /**
 635     For verbose output. Normally, it is suppressed, but
 636     might be activated if the user wishes to know more details about the program
 637     progress (another, but possibly confusing name for the same function is @b
 638     wxLogInfo).
 639 */
 640 void wxLogVerbose(const char * formatString, ... );
 641 void wxVLogVerbose(const char * formatString, va_list argPtr);
 642 //@}
 643
 644 /**
 645     This is used in headers to create a forward declaration of the
 646     wxGetApp function implemented by
 647     wxIMPLEMENT_APP. It creates the declaration
 648     @c className wxGetApp(void).
 649
 650     Example:
 651     @code
 652     wxDECLARE_APP(MyApp)
 653     @endcode
 654 */
 655 #define wxDECLARE_APP()     /* implementation is private */
 656
 657 /**
 658     Exits application after calling wxApp::OnExit.
 659     Should only be used in an emergency: normally the top-level frame
 660     should be deleted (after deleting all other frames) to terminate the
 661     application. See wxCloseEvent and wxApp.
 662 */
 663 void wxExit();
 664
 665 //@{
 666 /**
 667     For warnings - they are also normally shown to the user, but don't interrupt
 668     the program work.
 669 */
 670 void wxLogWarning(const char * formatString, ... );
 671 void wxVLogWarning(const char * formatString, va_list argPtr);
 672 //@}
 673
 674 //@{
 675 /**
 676     Like wxLogError, but also
 677     terminates the program with the exit code 3. Using @e abort() standard
 678     function also terminates the program with this exit code.
 679 */
 680 void wxLogFatalError(const char * formatString, ... );
 681 void wxVLogFatalError(const char * formatString,
 682                       va_list argPtr);
 683 //@}
 684
 685 /**
 686     If @e doIt is @true, the fatal exceptions (also known as general protection
 687     faults under Windows or segmentation violations in the Unix world) will be
 688     caught and passed to wxApp::OnFatalException.
 689     By default, i.e. before this function is called, they will be handled in the
 690     normal way which usually just means that the application will be terminated.
 691     Calling wxHandleFatalExceptions() with @e doIt equal to @false will restore
 692     this default behaviour.
 693
 694     Notice that this function is only available if
 695     @c wxUSE_ON_FATAL_EXCEPTION is 1 and under Windows platform this
 696     requires a compiler with support for SEH (structured exception handling) which
 697     currently means only Microsoft Visual C++ or a recent Borland C++ version.
 698 */
 699 bool wxHandleFatalExceptions(bool doIt = @true);
 700
 701 /**
 702     This is used in the application class implementation file to make the
 703     application class known to
 704     wxWidgets for dynamic construction. You use this instead of
 705
 706     Old form:
 707     @code
 708     MyApp myApp;
 709     @endcode
 710
 711     New form:
 712     @code
 713     IMPLEMENT_APP(MyApp)
 714     @endcode
 715
 716     See also DECLARE_APP.
 717 */
 718 #define IMPLEMENT_APP()     /* implementation is private */
 719
 720 /**
 721     Returns the error code from the last system call. This function uses
 722     @c errno on Unix platforms and @c GetLastError under Win32.
 723
 724     @sa wxSysErrorMsg, wxLogSysError
 725 */
 726 unsigned long wxSysErrorCode();
 727
 728 /**
 729     In a GUI application, this function posts @e event to the specified @e dest
 730     object using wxEvtHandler::AddPendingEvent.
 731     Otherwise, it dispatches @e event immediately using
 732     wxEvtHandler::ProcessEvent.
 733     See the respective documentation for details (and caveats).
 734 */
 735 void wxPostEvent(wxEvtHandler * dest, wxEvent& event);
 736
 737 //@{
 738 /**
 739     The functions to use for error messages, i.e. the messages that must be shown
 740     to the user. The default processing is to pop up a message box to inform the
 741     user about it.
 742 */
 743 void wxLogError(const char * formatString, ... );
 744 void wxVLogError(const char * formatString, va_list argPtr);
 745 //@}
 746
 747 //@{
 748 /**
 749     As @b wxLogDebug, trace functions only do something in debug build and
 750     expand to nothing in the release one. The reason for making
 751     it a separate function from it is that usually there are a lot of trace
 752     messages, so it might make sense to separate them from other debug messages.
 753
 754     The trace messages also usually can be separated into different categories and
 755     the second and third versions of this function only log the message if the
 756     @e mask which it has is currently enabled in wxLog. This
 757     allows to selectively trace only some operations and not others by changing
 758     the value of the trace mask (possible during the run-time).
 759
 760     For the second function (taking a string mask), the message is logged only if
 761     the mask has been previously enabled by the call to
 762     wxLog::AddTraceMask or by setting
 763     @ref overview_envvars "@c WXTRACE environment variable".
 764     The predefined string trace masks
 765     used by wxWidgets are:
 766
 767      wxTRACE_MemAlloc: trace memory allocation (new/delete)
 768      wxTRACE_Messages: trace window messages/X callbacks
 769      wxTRACE_ResAlloc: trace GDI resource allocation
 770      wxTRACE_RefCount: trace various ref counting operations
 771      wxTRACE_OleCalls: trace OLE method calls (Win32 only)
 772
 773     @b Caveats: since both the mask and the format string are strings,
 774     this might lead to function signature confusion in some cases:
 775     if you intend to call the format string only version of wxLogTrace,
 776     then add a %s format string parameter and then supply a second string parameter
 777     for that %s, the string mask version of wxLogTrace will erroneously get called instead, since you are supplying two string parameters to the function.
 778     In this case you'll unfortunately have to avoid having two leading
 779     string parameters, e.g. by adding a bogus integer (with its %d format string).
 780
 781     The third version of the function only logs the message if all the bits
 782     corresponding to the @e mask are set in the wxLog trace mask which can be
 783     set by wxLog::SetTraceMask. This version is less
 784     flexible than the previous one because it doesn't allow defining the user
 785     trace masks easily - this is why it is deprecated in favour of using string
 786     trace masks.
 787
 788      wxTraceMemAlloc: trace memory allocation (new/delete)
 789      wxTraceMessages: trace window messages/X callbacks
 790      wxTraceResAlloc: trace GDI resource allocation
 791      wxTraceRefCount: trace various ref counting operations
 792      wxTraceOleCalls: trace OLE method calls (Win32 only)
 793 */
 794 void wxLogTrace(const char * formatString, ... );
 795 void wxVLogTrace(const char * formatString, va_list argPtr);
 796 void wxLogTrace(const char * mask, const char * formatString,
 797                 ... );
 798 void wxVLogTrace(const char * mask,
 799                  const char * formatString,
 800                  va_list argPtr);
 801 void wxLogTrace(wxTraceMask mask, const char * formatString,
 802                 ... );
 803 void wxVLogTrace(wxTraceMask mask, const char * formatString,
 804                  va_list argPtr);
 805 //@}
 806
 807 /**
 808     Returns the error message corresponding to the given system error code. If
 809     @e errCode is 0 (default), the last error code (as returned by
 810     wxSysErrorCode) is used.
 811
 812     @sa wxSysErrorCode, wxLogSysError
 813 */
 814 const wxChar * wxSysErrorMsg(unsigned long errCode = 0);
 815
 816 /**
 817     This function is for use in console (wxBase) programs only. It must be called
 818     once for each previous successful call to wxInitialize.
 819 */
 820 void wxUninitialize();
 821
 822 //@{
 823 /**
 824     The right functions for debug output. They only do something in debug
 825     mode (when the preprocessor symbol __WXDEBUG__ is defined) and expand to
 826     nothing in release mode (otherwise).
 827 */
 828 void wxLogDebug(const char * formatString, ... );
 829 void wxVLogDebug(const char * formatString, va_list argPtr);
 830 //@}
 831
 832 /**
 833     This function doesn't exist in wxWidgets but it is created by using
 834     the IMPLEMENT_APP macro. Thus, before using it
 835     anywhere but in the same module where this macro is used, you must make it
 836     available using DECLARE_APP.
 837
 838     The advantage of using this function compared to directly using the global
 839     wxTheApp pointer is that the latter is of type @c wxApp * and so wouldn't
 840     allow you to access the functions specific to your application class but not
 841     present in wxApp while wxGetApp() returns the object of the right type.
 842 */
 843 wxAppDerivedClass wxGetApp();
 844
 845 //@{
 846 /**
 847     Messages logged by these functions will appear in the statusbar of the @e frame
 848     or of the top level application window by default (i.e. when using
 849     the second version of the functions).
 850
 851     If the target frame doesn't have a statusbar, the message will be lost.
 852 */
 853 void wxLogStatus(wxFrame * frame, const char * formatString,
 854                  ... );
 855 void wxVLogStatus(wxFrame * frame, const char * formatString,
 856                   va_list argPtr);
 857 void wxLogStatus(const char * formatString, ... );
 858 void wxVLogStatus(const char * formatString, va_list argPtr);
 859 //@}
 860
 861 /**
 862     This function is used in wxBase only and only if you don't create
 863     wxApp object at all. In this case you must call it from your
 864     @c main() function before calling any other wxWidgets functions.
 865
 866     If the function returns @false the initialization could not be performed,
 867     in this case the library cannot be used and
 868     wxUninitialize shouldn't be called neither.
 869
 870     This function may be called several times but
 871     wxUninitialize must be called for each successful
 872     call to this function.
 873 */
 874 bool wxInitialize();
 875
 876 /**
 877     This is used in headers to create a forward declaration of the
 878     wxGetApp function implemented by
 879     IMPLEMENT_APP. It creates the declaration
 880     @c className wxGetApp(void).
 881
 882     Example:
 883     @code
 884     DECLARE_APP(MyApp)
 885     @endcode
 886 */
 887 #define DECLARE_APP()     /* implementation is private */
 888
 889 /**
 890     Calls wxApp::Yield.
 891
 892     This function is kept only for backwards compatibility. Please use
 893     the wxApp::Yield method instead in any new code.
 894 */
 895 bool wxYield();
 896
 897 //@{
 898 /**
 899     Mostly used by wxWidgets itself, but might be handy for logging errors after
 900     system call (API function) failure. It logs the specified message text as well
 901     as the last system error code (@e errno or @e ::GetLastError() depending
 902     on the platform) and the corresponding error message. The second form
 903     of this function takes the error code explicitly as the first argument.
 904
 905     @sa wxSysErrorCode, wxSysErrorMsg
 906 */
 907 void wxLogSysError(const char * formatString, ... );
 908 void wxVLogSysError(const char * formatString,
 909                     va_list argPtr);
 910 //@}
 911
 912 //@{
 913 /**
 914     This initializes wxWidgets in a platform-dependent way. Use this if you are not
 915     using the default wxWidgets entry code (e.g. main or WinMain). For example, you
 916     can initialize wxWidgets from an Microsoft Foundation Classes application using
 917     this function.
 918
 919     The following overload of wxEntry is available under all platforms:
 920
 921     (notice that under Windows CE platform, and only there, the type of
 922     @e pCmdLine is @c wchar_t *, otherwise it is @c char *, even in
 923     Unicode build).
 924
 925     @remarks To clean up wxWidgets, call wxApp::OnExit followed by the static
 926                function wxApp::CleanUp. For example, if exiting from
 927                an MFC application that also uses wxWidgets:
 928
 929     @sa wxEntryStart
 930 */
 931 int wxEntry(int& argc, wxChar ** argv);
 932 int wxEntry(HINSTANCE hInstance,
 933             HINSTANCE hPrevInstance = @NULL,
 934             char * pCmdLine = @NULL,
 935             int nCmdShow = SW_SHOWNORMAL);
 936 //@}
 937