## wxApp

The wxApp class represents the application itself. It is used to:

- set and get application-wide properties;
- implement the windowing system message or event loop;
- initiate application processing via wxApp::OnInit;
- allow default processing of events not handled by other objects in the application.

You should use the macro IMPLEMENT_APP(appClass) in your application implementation file to tell wxWindows 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.

Derived from

wxEvtHandler
wxObject

Include files

<wx/app.h>

See also

wxApp overview

Members

wxApp::wxApp
wxApp::~wxApp
wxApp::argc
wxApp::argv
wxApp::CreateLogTarget
wxApp::Dispatch
wxApp::GetAppName
wxApp::GetAuto3D
wxApp::GetClassName
wxApp::GetExitOnFrameDelete
wxApp::GetTopWindow
wxApp::GetUseBestVisual
wxApp::GetVendorName
wxApp::ExitMainLoop
wxApp::Initialized
wxApp::MainLoop
wxApp::OnActivate
wxApp::OnExit
wxApp::OnCharHook
wxApp::OnFatalException
wxApp::OnIdle
wxApp::OnEndSession
wxApp::OnInit
wxApp::OnQueryEndSession
wxApp::ProcessMessage
wxApp::Pending
wxApp::SendIdleEvents
wxApp::SetAppName
wxApp::SetAuto3D
wxApp::SetClassName
wxApp::SetExitOnFrameDelete
wxApp::SetTopWindow
wxApp::SetVendorName
wxApp::GetStdIcon
wxApp::SetUseBestVisual

### wxApp::wxApp

void wxApp()

Constructor. Called implicitly with a definition of a wxApp object.

### wxApp::~wxApp

void ~wxApp()

Destructor. Will be called implicitly on program exit if the wxApp object is created on the stack.

### wxApp::argc

int argc

Number of command line arguments (after environment-specific processing).

### wxApp::argv

char ** argv

Command line arguments (after environment-specific processing).

### wxApp::CreateLogTarget

virtual wxLog* CreateLogTarget()

Creates a wxLog class for the application to use for logging errors. The default implementation returns a new wxLogGui class.

See also

wxLog

### wxApp::Dispatch

void Dispatch()

Dispatches the next event in the windowing system event queue.

This can be used for programming event loops, e.g.

      while (app.Pending())
        Dispatch();

See also

wxApp::Pending

### wxApp::GetAppName

wxString GetAppName() const

Returns the application name.

Remarks

wxWindows sets this to a reasonable default before calling wxApp::OnInit, but the application can reset it at will.

### wxApp::GetAuto3D

bool GetAuto3D() const

Returns TRUE if 3D control mode is on, FALSE otherwise.

See also

wxApp::SetAuto3D

### wxApp::GetClassName

wxString GetClassName() const

Gets the class name of the application. The class name may be used in a platform specific manner to refer to the application.

See also

wxApp::SetClassName

### wxApp::GetExitOnFrameDelete

bool GetExitFrameOnDelete() const

Returns TRUE if the application will exit when the top-level window is deleted, FALSE otherwise.

See also

wxApp::SetExitOnFrameDelete

### wxApp::GetTopWindow

wxWindow * GetTopWindow() const

Returns a pointer to the top window.

Remarks

If the top window hasn't been set using wxApp::SetTopWindow, this function will find the first top-level window (frame or dialog) and return that.

See also

SetTopWindow

### wxApp::GetUseBestVisual

bool GetUseBestVisual() const

Returns TRUE if the application will use the best visual on systems that support different visuals, FALSE otherwise.

See also

SetUseBestVisual

### wxApp::GetVendorName

wxString GetVendorName() const

Returns the application's vendor name.

### wxApp::ExitMainLoop

void ExitMainLoop()

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.

### wxApp::Initialized

bool Initialized()

Returns TRUE if the application has been initialized (i.e. if wxApp::OnInit has returned successfully). This can be useful for error message routines to determine which method of output is best for the current state of the program (some windowing systems may not like dialogs to pop up before the main loop has been entered).

### wxApp::MainLoop

int MainLoop()

Called by wxWindows on creation of the application. Override this if you wish to provide your own (environment-dependent) main loop.

Return value

Returns 0 under X, and the wParam of the WM_QUIT message under Windows.

### wxApp::OnActivate

void OnActivate(wxActivateEvent& event)

Provide this member function to know whether the application is being activated or deactivated (Windows only).

See also

wxWindow::OnActivate, wxActivateEvent

### wxApp::OnExit

int OnExit()

Provide this member function for any processing which needs to be done as the application is about to exit.

### wxApp::OnCharHook

void OnCharHook(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.

Parameters

event

The keypress event.

Remarks

Use the wxEVT_CHAR_HOOK macro in your event table.

If you use this member, you can selectively consume keypress events by calling wxEvent::Skip for characters the application is not interested in.

See also

wxKeyEvent, wxWindow::OnChar, wxWindow::OnCharHook, wxDialog::OnCharHook

### wxApp::OnFatalException

void OnFatalException()

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 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.

See also

wxHandleFatalExcetions

### wxApp::OnIdle

void OnIdle(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.

wxWindows' strategy for OnIdle processing is as follows. After pending user interface events for an application have all been processed, wxWindows 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 caling wxIdleEvent::RequestMore, wxWindows 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.

See also

wxWindow::OnIdle, wxIdleEvent, wxWindow::SendIdleEvents

### wxApp::OnEndSession

void OnEndSession(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 wxWindow::Close with a TRUE argument (forcing the application to close itself silently).

Remarks

Under X, OnEndSession is called in response to the 'die' event.

Under Windows, OnEndSession is called in response to the WM_ENDSESSION message.

See also

wxWindow::Close, wxWindow::OnCloseWindow, wxCloseEvent, wxApp::OnQueryEndSession

### wxApp::OnInit

bool OnInit()

This must be provided by the application, and will usually create the application's main window, optionally calling wxApp::SetTopWindow.

Return TRUE to continue processing, FALSE to exit the application.

### wxApp::OnQueryEndSession

void OnQueryEndSession(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 wxCloseEvent::CanVeto returns TRUE, the application is allowed to veto the shutdown by calling wxCloseEvent::Veto. 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 wxCloseEvent::GetForce. If this is TRUE, destroy the window using wxWindow::Destroy. If not, it is up to you whether you respond by destroying the window.

The default handler calls wxWindow::Close on the top-level window, and vetoes the shutdown if Close returns FALSE. This will be sufficient for many applications.

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.

See also

wxWindow::Close, wxWindow::OnCloseWindow, wxCloseEvent, wxApp::OnEndSession

### wxApp::ProcessMessage

bool ProcessMessage(MSG *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 wxWindows with another class library with its own message loop, you should make sure that this function is called to allow wxWindows to receive messages. For example, to allow co-existance with the Microsoft Foundation Classes, override the PreTranslateMessage function:

    // Provide wxWindows message loop compatibility
    BOOL CTheApp::PreTranslateMessage(MSG *msg)
    {
      if (wxTheApp && wxTheApp->ProcessMessage(msg))
        return TRUE;
      else
        return CWinApp::PreTranslateMessage(msg);
    }

### wxApp::Pending

bool Pending()

Returns TRUE if unprocessed events are in the window system event queue.

See also

wxApp::Dispatch

### wxApp::SendIdleEvents

bool SendIdleEvents()

Sends idle events to all top-level windows.

bool SendIdleEvents(wxWindow* win)

Sends idle events to a window and its children.

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.

See also

wxApp::OnIdle, wxWindow::OnIdle, wxIdleEvent

### wxApp::SetAppName

void SetAppName(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 wxWindows.

See also

wxApp::GetAppName

### wxApp::SetAuto3D

void SetAuto3D(const bool auto3D)

Switches automatic 3D controls on or off.

Parameters

auto3D

If TRUE, all controls will be created with 3D appearances unless overridden for a control or dialog. The default is TRUE

Remarks

This has an effect on Windows only.

See also

wxApp::GetAuto3D

### wxApp::SetClassName

void SetClassName(const wxString& name)

Sets the class name of the application. This may be used in a platform specific manner to refer to the application.

See also

wxApp::GetClassName

### wxApp::SetExitOnFrameDelete

void SetExitOnFrameDelete(bool flag)

Allows the programmer to specify whether the application will exit when the top-level frame is deleted.

Parameters

flag

If TRUE (the default), the application will exit when the top-level frame is deleted. If FALSE, the application will continue to run.

### wxApp::SetTopWindow

void SetTopWindow(wxWindow* window)

Sets the 'top' window. You can call this from within wxApp::OnInit to let wxWindows 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, wxWindows just uses the first frame or dialog in its top-level window list, when it needs to use the top window.

Parameters

window

The new top window.

See also

wxApp::GetTopWindow, wxApp::OnInit

### wxApp::SetVendorName

void SetVendorName(const wxString& name)

Sets the name of application's vendor. The name will be used in registry access. A default name is set by wxWindows.

See also

wxApp::GetVendorName

### wxApp::GetStdIcon

virtual wxIcon GetStdIcon(int which) const

Returns the icons used by wxWindows internally, e.g. the ones used for message boxes. This function is used internally and can be overridden by the user to change the default icons.

Parameters

which

One of the wxICON_XXX specifies which icon to return.

See wxMessageBox for a list of icon identifiers.

### wxApp::SetUseBestVisual

void SetUseBestVisual(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 appications are supposed to run in TrueColour mode.

Note that this function has to be called in the constructor of the `wxApp` instance and won't have any effect when called later on.

This function currently only has effect under GTK.

Parameters

flag

If TRUE, the app will use the best visual.