X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/90a1a975d4f1c07b53e0f70df7cde32ab1d84f53..d86c187031547bd2f0604adddef273deedea7907:/docs/latex/wx/tapp.tex diff --git a/docs/latex/wx/tapp.tex b/docs/latex/wx/tapp.tex index 563b3d085b..f87e1a4c8f 100644 --- a/docs/latex/wx/tapp.tex +++ b/docs/latex/wx/tapp.tex @@ -2,13 +2,13 @@ Classes: \helpref{wxApp}{wxapp} -A wxWindows application does not have a {\it main} procedure; the equivalent is the +A wxWidgets application does not have a {\it main} procedure; the equivalent is the \rtfsp\helpref{OnInit}{wxapponinit} member defined for a class derived from wxApp.\rtfsp \rtfsp{\it OnInit} will usually create a top window as a bare minimum. -Unlike in earlier versions of wxWindows, OnInit does not return a frame. Instead it -returns a boolean value which indicates whether processing should continue (TRUE) or not (FALSE). -You call \helpref{wxApp::SetTopWindow}{wxappsettopwindow} to let wxWindows know +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 \helpref{wxApp::SetTopWindow}{wxappsettopwindow} to let wxWidgets know about the top window. Note that the program's command line arguments, represented by {\it argc} @@ -22,7 +22,8 @@ is to explicitly delete child frames in the top-level frame's \helpref{wxCloseEv handler. In emergencies the \helpref{wxExit}{wxexit} function can be called to kill the -application. +application however normally the application shuts down automatically, +\helpref{see below}{wxappshutdownoverview}. An example of defining an application follows: @@ -39,27 +40,43 @@ bool DerivedApp::OnInit() { wxFrame *the_frame = new wxFrame(NULL, ID_MYFRAME, argv[0]); ... - the_frame->Show(TRUE); + the_frame->Show(true); SetTopWindow(the_frame); - return TRUE; + return true; } \end{verbatim} -Note the use of IMPLEMENT\_APP(appClass), which allows wxWindows to dynamically create an instance of the application object -at the appropriate point in wxWindows initialization. Previous versions of wxWindows used +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. +a reference to the application object. Otherwise you can only use the global +\texttt{wxTheApp} pointer which is of type \texttt{wxApp *}. -\subsection{Application shutdown} -\helpref{OnExit}{wxapponexit} is called when the application exits but {\it before} -wxWindows cleans its internal structures. Your should delete all wxWindows object that -your created by the time OnExit finishes. In particular, do {\bf not} destroy them +\subsection{Application shutdown}\label{wxappshutdownoverview} + +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 \helpref{Close()}{wxwindowclose} in response to the {\tt "Exit"} menu +command if your program has a single top level window. If this behaviour is not +desirable \helpref{wxApp::SetExitOnFrameDelete}{wxappsetexitonframedelete} 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 +\helpref{wxApp::OnInit}{wxapponinit} 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 \helpref{OnExit}{wxapponexit} +which is called when the application exits but {\it before} wxWidgets cleans up +its internal structures. You should delete all wxWidgets object that you +created by the time OnExit finishes. In particular, do {\bf not} destroy them from application class' destructor! For example, this code may crash: @@ -75,7 +92,7 @@ class MyApp : public wxApp The reason for that is that {\tt m\_helpCtrl} is a member object and is thus destroyed from MyApp destructor. But MyApp object is deleted after -wxWindows structures that wxCHMHelpController depends on were +wxWidgets structures that wxCHMHelpController depends on were uninitialized! The solution is to destroy HelpCtrl in {\it OnExit}: \begin{verbatim} @@ -99,3 +116,4 @@ int MyApp::OnExit() return 0; } \end{verbatim} +