\section{\class{wxApp}}\label{wxapp} The {\bf wxApp} class represents the application itself. It is used to: \begin{itemize}\itemsep=0pt \item set and get application-wide properties; \item implement the windowing system message or event loop; \item initiate application processing via \helpref{wxApp::OnInit}{wxapponinit}; \item allow default processing of events not handled by other objects in the application. \end{itemize} You should use the macro IMPLEMENT\_APP(appClass) in your application implementation file to tell wxWidgets how to create an instance of your application class. Use DECLARE\_APP(appClass) in a header file if you want the wxGetApp function (which returns a reference to your application object) to be visible to other files. \wxheading{Derived from} \helpref{wxEvtHandler}{wxevthandler}\\ \helpref{wxObject}{wxobject} \wxheading{Include files} \wxheading{See also} \helpref{wxApp overview}{wxappoverview} \latexignore{\rtfignore{\wxheading{Members}}} \membersection{wxApp::wxApp}\label{wxappctor} \func{void}{wxApp}{\void} Constructor. Called implicitly with a definition of a wxApp object. \membersection{wxApp::\destruct{wxApp}}\label{wxappdtor} \func{void}{\destruct{wxApp}}{\void} Destructor. Will be called implicitly on program exit if the wxApp object is created on the stack. \membersection{wxApp::argc}\label{wxappargc} \member{int}{argc} Number of command line arguments (after environment-specific processing). \membersection{wxApp::argv}\label{wxappargv} \member{char **}{argv} Command line arguments (after environment-specific processing). \membersection{wxApp::CreateLogTarget}\label{wxappcreatelogtarget} \func{virtual wxLog*}{CreateLogTarget}{\void} Creates a wxLog class for the application to use for logging errors. The default implementation returns a new wxLogGui class. \wxheading{See also} \helpref{wxLog}{wxlog} \membersection{wxApp::Dispatch}\label{wxappdispatch} \func{virtual void}{Dispatch}{\void} Dispatches the next event in the windowing system event queue. This can be used for programming event loops, e.g. \begin{verbatim} while (app.Pending()) Dispatch(); \end{verbatim} \wxheading{See also} \helpref{wxApp::Pending}{wxapppending} \membersection{wxApp::FilterEvent}\label{wxappfilterevent} \func{int}{FilterEvent}{\param{wxEvent\& }{event}} This function is called before processing any event and allows the application to preempt the processing of some events. If this method returns $-1$ the event is processed normally, otherwise either {\tt true} or {\tt false} should be returned and the event processing stops immediately considering that the event had been already processed (for the former return value) or that it is not going to be processed at all (for the latter one). \membersection{wxApp::ExitMainLoop}\label{wxappexitmainloop} \func{virtual void}{ExitMainLoop}{\void} Call this to explicitly exit the main message (event) loop. You should normally exit the main loop (and the application) by deleting the top window. \membersection{wxApp::GetAppName}\label{wxappgetappname} \constfunc{wxString}{GetAppName}{\void} Returns the application name. \wxheading{Remarks} wxWidgets sets this to a reasonable default before calling \helpref{wxApp::OnInit}{wxapponinit}, but the application can reset it at will. \membersection{wxApp::GetClassName}\label{wxappgetclassname} \constfunc{wxString}{GetClassName}{\void} Gets the class name of the application. The class name may be used in a platform specific manner to refer to the application. \wxheading{See also} \helpref{wxApp::SetClassName}{wxappsetclassname} \membersection{wxApp::GetExitOnFrameDelete}\label{wxappgetexitonframedelete} \constfunc{bool}{GetExitOnFrameDelete}{\void} Returns true if the application will exit when the top-level window is deleted, false otherwise. \wxheading{See also} \helpref{wxApp::SetExitOnFrameDelete}{wxappsetexitonframedelete},\\ \helpref{wxApp shutdown overview}{wxappshutdownoverview} \membersection{wxApp::GetTopWindow}\label{wxappgettopwindow} \constfunc{virtual wxWindow *}{GetTopWindow}{\void} Returns a pointer to the top window. \wxheading{Remarks} If the top window hasn't been set using \helpref{wxApp::SetTopWindow}{wxappsettopwindow}, this function will find the first top-level window (frame or dialog) and return that. \wxheading{See also} \helpref{SetTopWindow}{wxappsettopwindow} \membersection{wxApp::GetUseBestVisual}\label{wxappgetusebestvisual} \constfunc{bool}{GetUseBestVisual}{\void} Returns true if the application will use the best visual on systems that support different visuals, false otherwise. \wxheading{See also} \helpref{SetUseBestVisual}{wxappsetusebestvisual} \membersection{wxApp::GetVendorName}\label{wxappgetvendorname} \constfunc{wxString}{GetVendorName}{\void} Returns the application's vendor name. \membersection{wxApp::IsActive}\label{wxappisactive} \constfunc{bool}{IsActive}{\void} Returns \true if the application is active, i.e. if one of its windows is currently in the foreground. If this function returns \false and you need to attract users attention to the application, you may use \helpref{wxTopLevelWindow::RequestUserAttention}{wxtoplevelwindowrequestuserattention} to do it. \membersection{wxApp::IsMainLoopRunning}\label{wxappismainlooprunning} \func{static bool}{IsMainLoopRunning}{\void} Returns \true if the main event loop is currently running, i.e. if the application is inside \helpref{OnRun}{wxapponrun}. This can be useful to test whether the events can be dispatched. For example, if this function returns \false, non-blocking sockets cannot be used because the events from them would never be processed. \membersection{wxApp::MainLoop}\label{wxappmainloop} \func{virtual int}{MainLoop}{\void} Called by wxWidgets on creation of the application. Override this if you wish to provide your own (environment-dependent) main loop. \wxheading{Return value} Returns 0 under X, and the wParam of the WM\_QUIT message under Windows. %% VZ: OnXXX() functions should *not* be documented %% %%\membersection{wxApp::OnActivate}\label{wxapponactivate} %% %%\func{void}{OnActivate}{\param{wxActivateEvent\& }{event}} %% %%Provide this member function to know whether the application is being %%activated or deactivated (Windows only). %% %%\wxheading{See also} %% %%\helpref{wxWindow::OnActivate}{wxwindowonactivate}, \helpref{wxActivateEvent}{wxactivateevent} %% %%\membersection{wxApp::OnCharHook}\label{wxapponcharhook} %% %%\func{void}{OnCharHook}{\param{wxKeyEvent\&}{ event}} %% %%This event handler function is called (under Windows only) to allow the window to intercept keyboard events %%before they are processed by child windows. %% %%\wxheading{Parameters} %% %%\docparam{event}{The keypress event.} %% %%\wxheading{Remarks} %% %%Use the wxEVT\_CHAR\_HOOK macro in your event table. %% %%If you use this member, you can selectively consume keypress events by calling\rtfsp %%\helpref{wxEvent::Skip}{wxeventskip} for characters the application is not interested in. %% %%\wxheading{See also} %% %%\helpref{wxKeyEvent}{wxkeyevent}, \helpref{wxWindow::OnChar}{wxwindowonchar},\rtfsp %%\helpref{wxWindow::OnCharHook}{wxwindowoncharhook}, \helpref{wxDialog::OnCharHook}{wxdialogoncharhook} \membersection{wxApp::OnAssert}\label{wxapponassert} \func{void}{OnAssert}{\param{const wxChar }{*file}, \param{int }{line}, \param{const wxChar }{*cond}, \param{const wxChar }{*msg}} This function is called when an assert failure occurs, i.e. the condition specified in \helpref{wxASSERT}{wxassert} macro evaluated to {\tt false}. It is only called in debug mode (when {\tt \_\_WXDEBUG\_\_} is defined) as asserts are not left in the release code at all. The base class version show the default assert failure dialog box proposing to the user to stop the program, continue or ignore all subsequent asserts. \wxheading{Parameters} \docparam{file}{the name of the source file where the assert occured} \docparam{line}{the line number in this file where the assert occured} \docparam{cond}{the condition of the failed assert in string form} \docparam{msg}{the message specified as argument to \helpref{wxASSERT\_MSG}{wxassertmsg} or \helpref{wxFAIL\_MSG}{wxfailmsg}, will be {\tt NULL} if just \helpref{wxASSERT}{wxassert} or \helpref{wxFAIL}{wxfail} was used} \membersection{wxApp::OnCmdLineError}\label{wxapponcmdlineerror} \func{bool}{OnCmdLineError}{\param{wxCmdLineParser\& }{parser}} Called when command line parsing fails (i.e. an incorrect command line option was specified by the user). The default behaviour is to show the program usage text and abort the program. Return {\tt true} to continue normal execution or {\tt false} to return {\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program. \wxheading{See also} \helpref{OnInitCmdLine}{wxapponinitcmdline} \membersection{wxApp::OnCmdLineHelp}\label{wxapponcmdlinehelp} \func{bool}{OnCmdLineHelp}{\param{wxCmdLineParser\& }{parser}} Called when the help option ({\tt --help}) was specified on the command line. The default behaviour is to show the program usage text and abort the program. Return {\tt true} to continue normal execution or {\tt false} to return {\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program. \wxheading{See also} \helpref{OnInitCmdLine}{wxapponinitcmdline} \membersection{wxApp::OnCmdLineParsed}\label{wxapponcmdlineparsed} \func{bool}{OnCmdLineParsed}{\param{wxCmdLineParser\& }{parser}} Called after the command line had been successfully parsed. You may override this method to test for the values of the various parameters which could be set from the command line. Don't forget to call the base class version unless you want to suppress processing of the standard command line options. Return {\tt true} to continue normal execution or {\tt false} to return {\tt false} from \helpref{OnInit}{wxapponinit} thus terminating the program. \wxheading{See also} \helpref{OnInitCmdLine}{wxapponinitcmdline} \membersection{wxApp::OnExceptionInMainLoop}\label{wxapponexceptioninmainloop} \func{virtual bool}{OnExceptionInMainLoop}{\void} This function is called if an unhandled exception occurs inside the main application event loop. It can return \true to ignore the exception and to continue running the loop or \false to exit the loop and terminate the program. In the latter case it can also use C++ \texttt{throw} keyword to rethrow the current exception. The default behaviour of this function is the latter in all ports except under Windows where a dialog is shown to the user which allows him to choose between the different options. You may override this function in your class to do something more appropriate. Finally note that if the exception is rethrown from here, it can be caught in \helpref{OnUnhandledException}{wxapponunhandledexception}. \membersection{wxApp::OnExit}\label{wxapponexit} \func{virtual int}{OnExit}{\void} Override this member function for any processing which needs to be done as the application is about to exit. OnExit is called after destroying all application windows and controls, but before wxWidgets cleanup. Note that it is not called at all if \helpref{OnInit}{wxapponinit} failed. The return value of this function is currently ignored, return the same value as returned by the base class method if you override it. \membersection{wxApp::OnFatalException}\label{wxapponfatalexception} \func{void}{OnFatalException}{\void} This function may be called if something fatal happens: an unhandled exception under Win32 or a a fatal signal under Unix, for example. However, this will not happen by default: you have to explicitly call \helpref{wxHandleFatalExceptions}{wxhandlefatalexceptions} to enable this. Generally speaking, this function should only show a message to the user and return. You may attempt to save unsaved data but this is not guaranteed to work and, in fact, probably won't. \wxheading{See also} \helpref{wxHandleFatalExceptions}{wxhandlefatalexceptions} %% VZ: the wxApp event handler are private and should not be documented here! %% %%\membersection{wxApp::OnIdle}\label{wxapponidle} %% %%\func{void}{OnIdle}{\param{wxIdleEvent\& }{event}} %% %%Override this member function for any processing which needs to be done %%when the application is idle. You should call wxApp::OnIdle from your own function, %%since this forwards OnIdle events to windows and also performs garbage collection for %%windows whose destruction has been delayed. %% %%wxWidgets' strategy for OnIdle processing is as follows. After pending user interface events for an %%application have all been processed, wxWidgets sends an OnIdle event to the application object. wxApp::OnIdle itself %%sends an OnIdle event to each application window, allowing windows to do idle processing such as updating %%their appearance. If either wxApp::OnIdle or a window OnIdle function requested more time, by %%calling \helpref{wxIdleEvent::RequestMore}{wxidleeventrequestmore}, wxWidgets will send another OnIdle %%event to the application object. This will occur in a loop until either a user event is found to be %%pending, or OnIdle requests no more time. Then all pending user events are processed until the system %%goes idle again, when OnIdle is called, and so on. %% %%\wxheading{See also} %% %%\helpref{wxWindow::OnIdle}{wxwindowonidle}, \helpref{wxIdleEvent}{wxidleevent},\rtfsp %%\helpref{wxWindow::SendIdleEvents}{wxappsendidleevents} %% %%\membersection{wxApp::OnEndSession}\label{wxapponendsession} %% %%\func{void}{OnEndSession}{\param{wxCloseEvent\& }{event}} %% %%This is an event handler function called when the operating system or GUI session is %%about to close down. The application has a chance to silently save information, %%and can optionally close itself. %% %%Use the EVT\_END\_SESSION event table macro to handle query end session events. %% %%The default handler calls \helpref{wxWindow::Close}{wxwindowclose} with a true argument %%(forcing the application to close itself silently). %% %%\wxheading{Remarks} %% %%Under X, OnEndSession is called in response to the `die' event. %% %%Under Windows, OnEndSession is called in response to the WM\_ENDSESSION message. %% %%\wxheading{See also} %% %%\helpref{wxWindow::Close}{wxwindowclose},\rtfsp %%\helpref{wxWindow::OnCloseWindow}{wxwindowonclosewindow},\rtfsp %%\helpref{wxCloseEvent}{wxcloseevent},\rtfsp %%\helpref{wxApp::OnQueryEndSession}{wxapponqueryendsession} \membersection{wxApp::OnInit}\label{wxapponinit} \func{bool}{OnInit}{\void} This must be provided by the application, and will usually create the application's main window, optionally calling \helpref{wxApp::SetTopWindow}{wxappsettopwindow}. You may use \helpref{OnExit}{wxapponexit} to clean up anything initialized here, provided that the function returns \true. Notice that if you want to to use the command line processing provided by wxWidgets you have to call the base class version in the derived class OnInit(). Return \true to continue processing, \false to exit the application immediately. \membersection{wxApp::OnInitCmdLine}\label{wxapponinitcmdline} \func{void}{OnInitCmdLine}{\param{wxCmdLineParser\& }{parser}} Called from \helpref{OnInit}{wxapponinit} and may be used to initialize the parser with the command line options for this application. The base class versions adds support for a few standard options only. \membersection{wxApp::OnQueryEndSession}\label{wxapponqueryendsession} \func{void}{OnQueryEndSession}{\param{wxCloseEvent\& }{event}} This is an event handler function called when the operating system or GUI session is about to close down. Typically, an application will try to save unsaved documents at this point. If \helpref{wxCloseEvent::CanVeto}{wxcloseeventcanveto} returns true, the application is allowed to veto the shutdown by calling \helpref{wxCloseEvent::Veto}{wxcloseeventveto}. The application might veto the shutdown after prompting for documents to be saved, and the user has cancelled the save. Use the EVT\_QUERY\_END\_SESSION event table macro to handle query end session events. You should check whether the application is forcing the deletion of the window using \helpref{wxCloseEvent::GetForce}{wxcloseeventgetforce}. If this is true, destroy the window using \helpref{wxWindow::Destroy}{wxwindowdestroy}. If not, it is up to you whether you respond by destroying the window. The default handler calls \helpref{wxWindow::Close}{wxwindowclose} on the top-level window, and vetoes the shutdown if Close returns false. This will be sufficient for many applications. \wxheading{Remarks} Under X, OnQueryEndSession is called in response to the `save session' event. Under Windows, OnQueryEndSession is called in response to the WM\_QUERYENDSESSION message. \wxheading{See also} \helpref{wxWindow::Close}{wxwindowclose},\rtfsp \helpref{wxCloseEvent}{wxcloseevent}\rtfsp \membersection{wxApp::OnRun}\label{wxapponrun} \func{virtual int}{OnRun}{\void} This virtual function is where the execution of a program written in wxWidgets starts. The default implementation just enters the main loop and starts handling the events until it terminates, either because \helpref{ExitMainLoop}{wxappexitmainloop} has been explicitly called or because the last frame has been deleted and \helpref{GetExitOnFrameDelete}{wxappgetexitonframedelete} flag is \true (this is the default). The return value of this function becomes the exit code of the program, so it should return $0$ in case of successful termination. \membersection{wxApp::OnUnhandledException}\label{wxapponunhandledexception} \func{virtual void}{OnUnhandledException}{\void} This function is called when an unhandled C++ exception occurs inside \helpref{OnRun()}{wxapponrun} (the exceptions which occur during the program startup and shutdown might not be caught at all). Note that the exception type is lost by now, so if you want to really handle the exception you should override \helpref{OnRun()}{wxapponrun} and put a try/catch clause around the call to the base class version there. \membersection{wxApp::ProcessMessage}\label{wxappprocessmessage} \func{bool}{ProcessMessage}{\param{WXMSG *}{msg}} Windows-only function for processing a message. This function is called from the main message loop, checking for windows that may wish to process it. The function returns true if the message was processed, false otherwise. If you use wxWidgets with another class library with its own message loop, you should make sure that this function is called to allow wxWidgets to receive messages. For example, to allow co-existence with the Microsoft Foundation Classes, override the PreTranslateMessage function: \begin{verbatim} // Provide wxWidgets message loop compatibility BOOL CTheApp::PreTranslateMessage(MSG *msg) { if (wxTheApp && wxTheApp->ProcessMessage((WXMSW *)msg)) return true; else return CWinApp::PreTranslateMessage(msg); } \end{verbatim} \membersection{wxApp::Pending}\label{wxapppending} \func{virtual bool}{Pending}{\void} Returns true if unprocessed events are in the window system event queue. \wxheading{See also} \helpref{wxApp::Dispatch}{wxappdispatch} \membersection{wxApp::SendIdleEvents}\label{wxappsendidleevents} \func{bool}{SendIdleEvents}{\param{wxWindow*}{ win}, \param{wxIdleEvent\& }{event}} Sends idle events to a window and its children. Please note that this function is internal to wxWidgets and shouldn't be used by user code. \wxheading{Remarks} These functions poll the top-level windows, and their children, for idle event processing. If true is returned, more OnIdle processing is requested by one or more window. \wxheading{See also} \helpref{wxIdleEvent}{wxidleevent} \membersection{wxApp::SetAppName}\label{wxappsetappname} \func{void}{SetAppName}{\param{const wxString\& }{name}} Sets the name of the application. The name may be used in dialogs (for example by the document/view framework). A default name is set by wxWidgets. \wxheading{See also} \helpref{wxApp::GetAppName}{wxappgetappname} \membersection{wxApp::SetClassName}\label{wxappsetclassname} \func{void}{SetClassName}{\param{const wxString\& }{name}} Sets the class name of the application. This may be used in a platform specific manner to refer to the application. \wxheading{See also} \helpref{wxApp::GetClassName}{wxappgetclassname} \membersection{wxApp::SetExitOnFrameDelete}\label{wxappsetexitonframedelete} \func{void}{SetExitOnFrameDelete}{\param{bool}{ flag}} Allows the programmer to specify whether the application will exit when the top-level frame is deleted. \wxheading{Parameters} \docparam{flag}{If true (the default), the application will exit when the top-level frame is deleted. If false, the application will continue to run.} \wxheading{See also} \helpref{wxApp::GetExitOnFrameDelete}{wxappgetexitonframedelete},\\ \helpref{wxApp shutdown overview}{wxappshutdownoverview} \membersection{wxApp::SetTopWindow}\label{wxappsettopwindow} \func{void}{SetTopWindow}{\param{wxWindow* }{window}} Sets the `top' window. You can call this from within \helpref{wxApp::OnInit}{wxapponinit} to let wxWidgets know which is the main window. You don't have to set the top window; it is only a convenience so that (for example) certain dialogs without parents can use a specific window as the top window. If no top window is specified by the application, wxWidgets just uses the first frame or dialog in its top-level window list, when it needs to use the top window. \wxheading{Parameters} \docparam{window}{The new top window.} \wxheading{See also} \helpref{wxApp::GetTopWindow}{wxappgettopwindow}, \helpref{wxApp::OnInit}{wxapponinit} \membersection{wxApp::SetVendorName}\label{wxappsetvendorname} \func{void}{SetVendorName}{\param{const wxString\& }{name}} Sets the name of application's vendor. The name will be used in registry access. A default name is set by wxWidgets. \wxheading{See also} \helpref{wxApp::GetVendorName}{wxappgetvendorname} \membersection{wxApp::SetUseBestVisual}\label{wxappsetusebestvisual} \func{void}{SetUseBestVisual}{\param{bool}{ flag}} Allows the programmer to specify whether the application will use the best visual on systems that support several visual on the same display. This is typically the case under Solaris and IRIX, where the default visual is only 8-bit whereas certain applications are supposed to run in TrueColour mode. Note that this function has to be called in the constructor of the {\tt wxApp} instance and won't have any effect when called later on. This function currently only has effect under GTK. \wxheading{Parameters} \docparam{flag}{If true, the app will use the best visual.} \membersection{wxApp::HandleEvent}\label{wxapphandleevent} \constfunc{virtual void}{HandleEvent}{\param{wxEvtHandler}{ *handler}, \param{wxEventFunction}{ func}, \param{wxEvent\& }{event}} This function simply invokes the given method \arg{func} of the specified event handler \arg{handler} with the \arg{event} as parameter. It exists solely to allow to catch the C++ exceptions which could be thrown by all event handlers in the application in one place: if you want to do this, override this function in your wxApp-derived class and add try/catch clause(s) to it. \membersection{wxApp::Yield}\label{wxappyield} \func{bool}{Yield}{\param{bool}{ onlyIfNeeded = false}} Yields control to pending messages in the windowing system. This can be useful, for example, when a time-consuming process writes to a text window. Without an occasional yield, the text window will not be updated properly, and on systems with cooperative multitasking, such as Windows 3.1 other processes will not respond. Caution should be exercised, however, since yielding may allow the user to perform actions which are not compatible with the current task. Disabling menu items or whole menus during processing can avoid unwanted reentrance of code: see \helpref{::wxSafeYield}{wxsafeyield} for a better function. Note that Yield() will not flush the message logs. This is intentional as calling Yield() is usually done to quickly update the screen and popping up a message box dialog may be undesirable. If you do wish to flush the log messages immediately (otherwise it will be done during the next idle loop iteration), call \helpref{wxLog::FlushActive}{wxlogflushactive}. Calling Yield() recursively is normally an error and an assert failure is raised in debug build if such situation is detected. However if the the {\it onlyIfNeeded} parameter is {\tt true}, the method will just silently return {\tt false} instead.