/////////////////////////////////////////////////////////////////////////////
-// Name: app
+// Name: app.h
// Purpose: topic overview
// Author: wxWidgets team
// RCS-ID: $Id$
/*!
- @page app_overview wxApp overview
+ @page overview_app wxApp overview
Classes: #wxApp
A wxWidgets application does not have a @e main procedure; the equivalent is the
#OnInit member defined for a class derived from wxApp.
+
@e OnInit will usually create a top window as a bare minimum.
Unlike in earlier versions of wxWidgets, OnInit does not return a frame. Instead it
- returns a boolean value which indicates whether processing should continue (@true) or not (@false).
- You call wxApp::SetTopWindow to let wxWidgets know
- about the top window.
+ returns a boolean value which indicates whether processing should continue (@true)
+ or not (@false). You call wxApp::SetTopWindow to let wxWidgets know about the top window.
+
Note that the program's command line arguments, represented by @e argc
and @e argv, are available from within wxApp member functions.
+
An application closes by destroying all windows. Because all frames must
be destroyed for the application to exit, it is advisable to use parent
frames wherever possible when creating new frames, so that deleting the
top level frame will automatically delete child frames. The alternative
is to explicitly delete child frames in the top-level frame's #wxCloseEvent
handler.
+
In emergencies the #wxExit function can be called to kill the
application however normally the application shuts down automatically,
- @ref appshutdown_overview.
+ see @ref overview_app_shutdown.
+
An example of defining an application follows:
@code
}
@endcode
- Note the use of IMPLEMENT_APP(appClass), which allows wxWidgets to dynamically create an instance of the application object
- at the appropriate point in wxWidgets initialization. Previous versions of wxWidgets used
- to rely on the creation of a global application object, but this is no longer recommended,
- because required global initialization may not have been performed at application object
- construction time.
- You can also use DECLARE_APP(appClass) in a header file to declare the wxGetApp function which returns
- a reference to the application object. Otherwise you can only use the global
+ Note the use of IMPLEMENT_APP(appClass), which allows wxWidgets to dynamically create
+ an instance of the application object at the appropriate point in wxWidgets initialization.
+ Previous versions of wxWidgets used to rely on the creation of a global application object,
+ but this is no longer recommended, because required global initialization may not have
+ been performed at application object construction time.
+
+ You can also use DECLARE_APP(appClass) in a header file to declare the wxGetApp function
+ which returns a reference to the application object. Otherwise you can only use the global
@c wxTheApp pointer which is of type @c wxApp *.
- @ref appshutdown_overview
- @section wxappshutdownoverview Application shutdown
+ @section overview_app_shutdown Application shutdown
The application normally shuts down when the last of its top level windows is
closed. This is normally the expected behaviour and means that it is enough to
- call #Close() in response to the @c "Exit" menu
- command if your program has a single top level window. If this behaviour is not
- desirable wxApp::SetExitOnFrameDelete can
- be called to change it. Note that starting from wxWidgets 2.3.3 such logic
- doesn't apply for the windows shown before the program enters the main loop: in
- other words, you can safely show a dialog from
- wxApp::OnInit and not be afraid that your application
- terminates when this dialog -- which is the last top level window for the
- moment -- is closed.
+ call #Close() in response to the @c "Exit" menu command if your program has a single
+ top level window. If this behaviour is not desirable wxApp::SetExitOnFrameDelete can
+ be called to change it.
+
+ Note that starting from wxWidgets 2.3.3 such logic doesn't apply for the windows shown
+ before the program enters the main loop: in other words, you can safely show a dialog from
+ wxApp::OnInit and not be afraid that your application terminates when this dialog --
+ which is the last top level window for the moment -- is closed.
Another aspect of the application shutdown is #OnExit
which is called when the application exits but @e before wxWidgets cleans up
its internal structures. You should delete all wxWidgets object that you
- created by the time OnExit finishes. In particular, do @b not destroy them
- from application class' destructor!
+ created by the time OnExit finishes.
+
+ In particular, do @b not destroy them from application class' destructor!
For example, this code may crash:
@code
}
@endcode
- */
-
+*/