X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/3c4f71cc3d63fb7bdfbd6cec3e39c8a8679f3e60..2e18fe7139558b3cb592a04a4e4668319a966ebf:/docs/doxygen/overviews/helloworld.h diff --git a/docs/doxygen/overviews/helloworld.h b/docs/doxygen/overviews/helloworld.h index 8bf019fac3..ff5c20d287 100644 --- a/docs/doxygen/overviews/helloworld.h +++ b/docs/doxygen/overviews/helloworld.h @@ -3,178 +3,286 @@ // Purpose: topic overview // Author: wxWidgets team // RCS-ID: $Id$ -// Licence: wxWindows license +// Licence: wxWindows licence ///////////////////////////////////////////////////////////////////////////// /** - @page overview_helloworld Hello World Example - - Many people have requested a mini-sample to be published here - so that some quick judgment concerning syntax - and basic principles can be made, so here we go. - - First, you have to include wxWidgets' header files, of course. This can - be done on a file by file basis (such as @#include "wx/window.h") - or using one global include (@#include "wx/wx.h"). This is - also useful on platforms which support precompiled headers such - as all major compilers on the Windows platform and GCC on Unix platforms. - - @code - // - // file name: hworld.cpp - // - // purpose: wxWidgets "Hello world" - // - - // For compilers that support precompilation, includes "wx/wx.h". - #include "wx/wxprec.h" - - #ifdef __BORLANDC__ - #pragma hdrstop - #endif - - #ifndef WX_PRECOMP - #include "wx/wx.h" - #endif - @endcode - - Practically every app should define a new class derived from wxApp. - By overriding wxApp's OnInit() the program can be initialized, - e.g. by creating a new main window. - - @code - class MyApp: public wxApp - { - virtual bool OnInit(); - }; - @endcode - - The main window is created by deriving a class from wxFrame and - giving it a menu and a status bar in its constructor. Also, any class - that wishes to respond to any "event" (such as mouse clicks or - messages from the menu or a button) must declare an event table - using the macro below. - - Finally, the way to react to such events must be done in "handlers". - In our sample, we react to two menu items, one for "Quit" and one for - displaying an "About" window. These handlers should not be virtual. - - @code - class MyFrame: public wxFrame - { - public: - MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size); - - void OnQuit(wxCommandEvent& event); - void OnAbout(wxCommandEvent& event); - - private: - DECLARE_EVENT_TABLE() - }; - @endcode - - In order to be able to react to a menu command, it must be given a unique - identifier such as a const or an enum. - - @code - enum - { - ID_Quit = 1, - ID_About, - }; - @endcode - - We then proceed to actually implement an event table in which the events - are routed to their respective handler functions in the class MyFrame. - - There are predefined macros for routing all common events, ranging from - the selection of a list box entry to a resize event when a user resizes - a window on the screen. If -1 is given as the ID, the given handler will be - invoked for any event of the specified type, so that you could add just - one entry in the event table for all menu commands or all button commands etc. - - The origin of the event can still be distinguished in the event handler as - the (only) parameter in an event handler is a reference to a wxEvent object, - which holds various information about the event (such as the ID of and a - pointer to the class, which emitted the event). - - @code - BEGIN_EVENT_TABLE(MyFrame, wxFrame) - EVT_MENU(ID_Quit, MyFrame::OnQuit) - EVT_MENU(ID_About, MyFrame::OnAbout) - END_EVENT_TABLE() - @endcode - - As in all programs there must be a "main" function. Under wxWidgets main is implemented - using this macro, which creates an application instance and starts the program. - - @code - IMPLEMENT_APP(MyApp) - @endcode - - As mentioned above, wxApp::OnInit() is called upon startup and should be - used to initialize the program, maybe showing a "splash screen" and creating - the main window (or several). The frame should get a title bar text ("Hello World") - and a position and start-up size. One frame can also be declared to be the - top window. Returning @true indicates a successful initialization. - - @code - bool MyApp::OnInit() - { - MyFrame *frame = new MyFrame( "Hello World", wxPoint(50,50), wxSize(450,340) ); - frame->Show( true ); - SetTopWindow( frame ); - return true; - } - @endcode - - In the constructor of the main window (or later on) we create a menu with two menu - items as well as a status bar to be shown at the bottom of the main window. Both have - to be "announced" to the frame with respective calls. - - @code - MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size) - : wxFrame((wxFrame *)NULL, -1, title, pos, size) - { - wxMenu *menuFile = new wxMenu; - - menuFile->Append( ID_About, "" ); - menuFile->AppendSeparator(); - menuFile->Append( ID_Quit, "E" ); - - wxMenuBar *menuBar = new wxMenuBar; - menuBar->Append( menuFile, "" ); - - SetMenuBar( menuBar ); - - CreateStatusBar(); - SetStatusText( "Welcome to wxWidgets!" ); - } - @endcode - - Here are the actual event handlers. MyFrame::OnQuit() closes the main window - by calling Close(). The parameter @true indicates that other windows have no veto - power such as after asking "Do you really want to close?". If there is no other - main window left, the application will quit. - - @code - void MyFrame::OnQuit(wxCommandEvent& WXUNUSED(event)) - { - Close( true ); - } - @endcode - - MyFrame::OnAbout() will display a small window with some text in it. In this - case a typical "About" window with information about the program. - - @code - void MyFrame::OnAbout(wxCommandEvent& WXUNUSED(event)) - { - wxMessageBox( "This is a wxWidgets' Hello world sample", - "About Hello World", wxOK | wxICON_INFORMATION ); - } - @endcode +@page overview_helloworld Hello World Example + +This page shows a very simple wxWidgets program that can be used as a skeleton +for your own code. While it does nothing very useful, it introduces a couple of +important concepts and explains how to write a working wxWidgets application. + +First, you have to include wxWidgets' header files, of course. This can +be done on a file by file basis (such as @c wx/window.h) or using one +global include (@c wx/wx.h) which includes most of the commonly needed headers +(although not all of them as there are simply too many wxWidgets headers to +pull in all of them). For the platforms with support for precompiled headers, +as indicated by @c WX_PRECOMP, this global header is already included by @c +wx/wxprec.h so we only include it for the other ones: + +@code +// wxWidgets "Hello world" Program + +// For compilers that support precompilation, includes "wx/wx.h". +#include + +#ifndef WX_PRECOMP + #include +#endif +@endcode + +Practically every app should define a new class derived from wxApp. By +overriding wxApp's OnInit() virtual method the program can be initialized, e.g. +by creating a new main window. + +@code +class MyApp: public wxApp +{ +public: + virtual bool OnInit(); +}; +@endcode + +The main window is created by deriving a class from wxFrame and +giving it a menu and a status bar in its constructor. Also, any class +that wishes to respond to any "event" (such as mouse clicks or +messages from the menu or a button) must declare an event table +using the macro below. + +Finally, the way to react to such events must be done in "handlers". +In our sample, we react to three menu items, one for our custom menu +command and two for the standard "Exit" and "About" commands (any program +should normally implement the latter two). Notice that these handlers +don't need to be neither virtual nor public. + +@code +class MyFrame: public wxFrame +{ +public: + MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size); + +private: + void OnHello(wxCommandEvent& event); + void OnExit(wxCommandEvent& event); + void OnAbout(wxCommandEvent& event); + + wxDECLARE_EVENT_TABLE(); +}; +@endcode + +In order to be able to react to a menu command, it must be given a unique +identifier which can be defined as a const variable or an enum element. The +latter is often used because typically many such constants will be needed: + +@code +enum +{ + ID_Hello = 1 +}; +@endcode + +Notice that you don't need to define identifiers for the "About" and "Exit" +We then proceed to actually implement an event table in which the events +are routed to their respective handler functions in the class MyFrame. + +There are predefined macros for routing all common events, ranging from +the selection of a list box entry to a resize event when a user resizes +a window on the screen. If @c wxID_ANY is given as the ID, the given handler will be +invoked for any event of the specified type, so that you could add just +one entry in the event table for all menu commands or all button commands etc. + +The origin of the event can still be distinguished in the event handler as +the (only) parameter in an event handler is a reference to a wxEvent object, +which holds various information about the event (such as the ID of and a +pointer to the class, which emitted the event). + +@code +wxBEGIN_EVENT_TABLE(MyFrame, wxFrame) + EVT_MENU(ID_Hello, MyFrame::OnHello) + EVT_MENU(wxID_EXIT, MyFrame::OnExit) + EVT_MENU(wxID_ABOUT, MyFrame::OnAbout) +wxEND_EVENT_TABLE() +@endcode + +As in all programs there must be a "main" function. Under wxWidgets main is implemented +using this macro, which creates an application instance and starts the program. + +@code +wxIMPLEMENT_APP(MyApp) +@endcode + +As mentioned above, wxApp::OnInit() is called upon startup and should be +used to initialize the program, maybe showing a "splash screen" and creating +the main window (or several). The frame should get a title bar text ("Hello World") +and a position and start-up size. One frame can also be declared to be the +top window. Returning @true indicates a successful initialization. + +@code +bool MyApp::OnInit() +{ + MyFrame *frame = new MyFrame( "Hello World", wxPoint(50,50), wxSize(450,340) ); + frame->Show( true ); + return true; +} +@endcode + +In the constructor of the main window (or later on) we create a menu with our menu +items as well as a status bar to be shown at the bottom of the main window. Both have +to be associated with the frame with respective calls. + +@code +MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size) + : wxFrame(NULL, wxID_ANY, title, pos, size) +{ + wxMenu *menuFile = new wxMenu; + menuFile->Append(ID_Hello, "&Hello...\tCtrl-H", + "Help string shown in status bar for this menu item"); + menuFile->AppendSeparator(); + menuFile->Append(wxID_EXIT); + + wxMenu *menuHelp = new wxMenu; + menuHelp->Append(wxID_ABOUT); + + wxMenuBar *menuBar = new wxMenuBar; + menuBar->Append( menuFile, "&File" ); + menuBar->Append( menuHelp, "&Help" ); + + SetMenuBar( menuBar ); + + CreateStatusBar(); + SetStatusText( "Welcome to wxWidgets!" ); +} +@endcode + +Notice that we don't need to specify the labels for the standard menu items +@c wxID_ABOUT and @c wxID_EXIT, they will be given standard (even correctly +translated) labels and also standard accelerators correct for the current +platform making your program behaviour more native. For this reason you should +prefer reusing the standard ids (see @ref page_stockitems) if possible. + +Here are the standard event handlers implementations. MyFrame::OnExit() closes +the main window by calling Close(). The parameter @true indicates that other +windows have no veto power such as after asking "Do you really want to close?". +If there is no other main window left, the application will quit. + +@code +void MyFrame::OnExit(wxCommandEvent& event) +{ + Close( true ); +} +@endcode + +MyFrame::OnAbout() will display a small window with some text in it. In this +case a typical "About" window with information about the program. + +@code +void MyFrame::OnAbout(wxCommandEvent& event) +{ + wxMessageBox( "This is a wxWidgets' Hello world sample", + "About Hello World", wxOK | wxICON_INFORMATION ); +} +@endcode + +The implementation of custom menu command handler may perform whatever task +your program needs to do, in this case we will simply show a message from it as +befits a hello world example: +@code +void MyFrame::OnHello(wxCommandEvent& event) +{ + wxLogMessage("Hello world from wxWidgets!"); +} +@endcode + +Here is the entire program that can be copied and pasted: +@code +// wxWidgets "Hello world" Program + +// For compilers that support precompilation, includes "wx/wx.h". +#include + +#ifndef WX_PRECOMP + #include +#endif + +class MyApp: public wxApp +{ +public: + virtual bool OnInit(); +}; + +class MyFrame: public wxFrame +{ +public: + MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size); + +private: + void OnHello(wxCommandEvent& event); + void OnExit(wxCommandEvent& event); + void OnAbout(wxCommandEvent& event); + + wxDECLARE_EVENT_TABLE(); +}; + +enum +{ + ID_Hello = 1 +}; + +wxBEGIN_EVENT_TABLE(MyFrame, wxFrame) + EVT_MENU(ID_Hello, MyFrame::OnHello) + EVT_MENU(wxID_EXIT, MyFrame::OnExit) + EVT_MENU(wxID_ABOUT, MyFrame::OnAbout) +wxEND_EVENT_TABLE() + +wxIMPLEMENT_APP(MyApp); + +bool MyApp::OnInit() +{ + MyFrame *frame = new MyFrame( "Hello World", wxPoint(50,50), wxSize(450,340) ); + frame->Show( true ); + return true; +} + +MyFrame::MyFrame(const wxString& title, const wxPoint& pos, const wxSize& size) + : wxFrame(NULL, wxID_ANY, title, pos, size) +{ + wxMenu *menuFile = new wxMenu; + menuFile->Append(ID_Hello, "&Hello...\tCtrl-H", + "Help string shown in status bar for this menu item"); + menuFile->AppendSeparator(); + menuFile->Append(wxID_EXIT); + + wxMenu *menuHelp = new wxMenu; + menuHelp->Append(wxID_ABOUT); + + wxMenuBar *menuBar = new wxMenuBar; + menuBar->Append( menuFile, "&File" ); + menuBar->Append( menuHelp, "&Help" ); + + SetMenuBar( menuBar ); + + CreateStatusBar(); + SetStatusText( "Welcome to wxWidgets!" ); +} + +void MyFrame::OnExit(wxCommandEvent& event) +{ + Close( true ); +} + +void MyFrame::OnAbout(wxCommandEvent& event) +{ + wxMessageBox( "This is a wxWidgets' Hello world sample", + "About Hello World", wxOK | wxICON_INFORMATION ); +} + +void MyFrame::OnHello(wxCommandEvent& event) +{ + wxLogMessage("Hello world from wxWidgets!"); +} +@endcode */