1\section{Event handling overview}\label{eventhandlingoverview} 2 3Classes: \helpref{wxEvtHandler}{wxevthandler}, \helpref{wxWindow}{wxwindow}, \helpref{wxEvent}{wxevent} 4 5\subsection{Introduction}\label{eventintroduction} 6 7Before version 2.0 of wxWidgets, events were handled by the application 8either by supplying callback functions, or by overriding virtual member 9functions such as {\bf OnSize}. 10 11From wxWidgets 2.0, {\it event tables} are used instead, with a few exceptions. 12 13An event table is placed in an implementation file to tell wxWidgets how to map 14events to member functions. These member functions are not virtual functions, but 15they are all similar in form: they take a single wxEvent-derived argument, and have a void return 16type. 17 18Here's an example of an event table. 19 20\begin{verbatim} 21BEGIN_EVENT_TABLE(MyFrame, wxFrame) 22 EVT_MENU (wxID_EXIT, MyFrame::OnExit) 23 EVT_MENU (DO_TEST, MyFrame::DoTest) 24 EVT_SIZE ( MyFrame::OnSize) 25 EVT_BUTTON (BUTTON1, MyFrame::OnButton1) 26END_EVENT_TABLE() 27\end{verbatim} 28 29The first two entries map menu commands to two different member functions. The 30EVT\_SIZE macro doesn't need a window identifier, since normally you are only 31interested in the current window's size events. 32 33The EVT\_BUTTON macro demonstrates that the originating event does not have to 34come from the window class implementing the event table -- if the event source 35is a button within a panel within a frame, this will still work, because event 36tables are searched up through the hierarchy of windows for the command events. 37In this case, the button's event table will be searched, then the parent 38panel's, then the frame's. 39 40As mentioned before, the member functions that handle events do not have to be 41virtual. Indeed, the member functions should not be virtual as the event 42handler ignores that the functions are virtual, i.e. overriding a virtual 43member function in a derived class will not have any effect. These member 44functions take an event argument, and the class of event differs according to 45the type of event and the class of the originating window. For size events, 46\helpref{wxSizeEvent}{wxsizeevent} is used. For menu commands and most 47control commands (such as button presses), 48\helpref{wxCommandEvent}{wxcommandevent} is used. When controls get more 49complicated, then specific event classes are used, such as 50\helpref{wxTreeEvent}{wxtreeevent} for events from 51\helpref{wxTreeCtrl}{wxtreectrl} windows. 52 53As well as the event table in the implementation file, there must also be a 54DECLARE\_EVENT\_TABLE macro somewhere in the class declaration. For example: 55 56{\small% 57\begin{verbatim} 58class MyFrame : public wxFrame 59{ 60public: 61 ... 62 void OnExit(wxCommandEvent& event); 63 void OnSize(wxSizeEvent& event); 64 65protected: 66 int m_count; 67 ... 68 69 DECLARE_EVENT_TABLE() 70}; 71\end{verbatim} 72}% 73 74Note that this macro may occur in any section of the class (public, protected 75or private) but that it is probably better to insert it at the end, as shown, 76because this macro implicitly changes the access to protected which may be 77quite unexpected if there is anything following it. 78 79Finally, if you don't like using macros for static initialization of the event 80tables you may also use \helpref{wxEvtHandler::Connect}{wxevthandlerconnect} to 81connect the events to the handlers dynamically, during run-time. See the 82\helpref{event sample}{sampleevent} for an example of doing it. 83 84 85\subsection{How events are processed}\label{eventprocessing} 86 87When an event is received from the windowing system, wxWidgets calls 88\helpref{wxEvtHandler::ProcessEvent}{wxevthandlerprocessevent} on the first 89event handler object belonging to the window generating the event. 90 91It may be noted that wxWidgets' event processing system implements something 92very close to virtual methods in normal C++, i.e. it is possible to alter 93the behaviour of a class by overriding its event handling functions. In 94many cases this works even for changing the behaviour of native controls. 95For example it is possible to filter out a number of key events sent by the 96system to a native text control by overriding wxTextCtrl and defining a 97handler for key events using EVT\_KEY\_DOWN. This would indeed prevent 98any key events from being sent to the native control - which might not be 99what is desired. In this case the event handler function has to call Skip() 100so as to indicate that the search for the event handler should continue. 101 102To summarize, instead of explicitly calling the base class version as you 103would have done with C++ virtual functions (i.e. {\it wxTextCtrl::OnChar()}), 104you should instead call \helpref{Skip}{wxeventskip}. 105 106In practice, this would look like this if the derived text control only 107accepts 'a' to 'z' and 'A' to 'Z': 108 109{\small% 110\begin{verbatim} 111void MyTextCtrl::OnChar(wxKeyEvent& event) 112{ 113 if ( isalpha( event.KeyCode() ) ) 114 { 115 // key code is within legal range. we call event.Skip() so the 116 // event can be processed either in the base wxWidgets class 117 // or the native control. 118 119 event.Skip(); 120 } 121 else 122 { 123 // illegal key hit. we don't call event.Skip() so the 124 // event is not processed anywhere else. 125 126 wxBell(); 127 } 128} 129\end{verbatim} 130}% 131 132 133The normal order of event table searching by ProcessEvent is as follows: 134 135\begin{enumerate}\itemsep=0pt 136\item If the object is disabled (via a call to \helpref{wxEvtHandler::SetEvtHandlerEnabled}{wxevthandlersetevthandlerenabled}) 137the function skips to step (6). 138\item If the object is a wxWindow, {\bf ProcessEvent} is recursively called on the window's\rtfsp 139\helpref{wxValidator}{wxvalidator}. If this returns true, the function exits. 140\item {\bf SearchEventTable} is called for this event handler. If this fails, the base 141class table is tried, and so on until no more tables exist or an appropriate function was found, 142in which case the function exits. 143\item The search is applied down the entire chain of event handlers (usually the chain has a length 144of one). If this succeeds, the function exits. 145\item If the object is a wxWindow and the event is set to set to propagate (in the library only 146wxCommandEvent based events are set to propagate), {\bf ProcessEvent} is recursively applied 147to the parent window's event handler. If this returns true, the function exits. 148\item Finally, {\bf ProcessEvent} is called on the wxApp object. 149\end{enumerate} 150 151{\bf Pay close attention to Step 5.} People often overlook or get 152confused by this powerful feature of the wxWidgets event processing 153system. To put it a different way, events set to propagate 154(\helpref{See: wxEvent::ShouldPropagate}{wxeventshouldpropagate}) 155(most likely derived either directly or indirectly from wxCommandEvent) 156will travel up the containment hierarchy from child to parent until the 157maximal propagation level is reached or an event handler is found that 158doesn't call \helpref{event.Skip()}{wxeventskip}. 159 160Finally, there is another additional complication (which, in fact, simplifies 161life of wxWidgets programmers significantly): when propagating the command 162events upwards to the parent window, the event propagation stops when it 163reaches the parent dialog, if any. This means that you don't risk to get 164unexpected events from the dialog controls (which might be left unprocessed by 165the dialog itself because it doesn't care about them) when a modal dialog is 166popped up. The events do propagate beyond the frames, however. The rationale 167for this choice is that there are only a few frames in a typical application 168and their parent-child relation are well understood by the programmer while it 169may be very difficult, if not impossible, to track down all the dialogs which 170may be popped up in a complex program (remember that some are created 171automatically by wxWidgets). If you need to specify a different behaviour for 172some reason, you can use 173\helpref{SetExtraStyle(wxWS\_EX\_BLOCK\_EVENTS)}{wxwindowsetextrastyle} 174explicitly to prevent the events from being propagated beyond the given window 175or unset this flag for the dialogs which have it on by default. 176 177Typically events that deal with a window as a window (size, motion, 178paint, mouse, keyboard, etc.) are sent only to the window. Events 179that have a higher level of meaning and/or are generated by the window 180itself, (button click, menu select, tree expand, etc.) are command 181events and are sent up to the parent to see if it is interested in the 182event. 183 184Note that your application may wish to override ProcessEvent to redirect processing of 185events. This is done in the document/view framework, for example, to allow event handlers 186to be defined in the document or view. To test for command events (which will probably 187be the only events you wish to redirect), you may use 188\helpref{wxEvent::IsCommandEvent}{wxeventiscommandevent} for efficiency, 189instead of using the slower run-time type system. 190 191As mentioned above, only command events are recursively applied to the parents event 192handler in the library itself. As this quite often causes confusion for users, 193here is a list of system events which will NOT get sent to the parent's event handler: 194 195\begin{twocollist}\itemsep=0pt 196\twocolitem{\helpref{wxEvent}{wxevent}}{The event base class} 197\twocolitem{\helpref{wxActivateEvent}{wxactivateevent}}{A window or application activation event} 198\twocolitem{\helpref{wxCloseEvent}{wxcloseevent}}{A close window or end session event} 199\twocolitem{\helpref{wxEraseEvent}{wxeraseevent}}{An erase background event} 200\twocolitem{\helpref{wxFocusEvent}{wxfocusevent}}{A window focus event} 201\twocolitem{\helpref{wxKeyEvent}{wxkeyevent}}{A keypress event} 202\twocolitem{\helpref{wxIdleEvent}{wxidleevent}}{An idle event} 203\twocolitem{\helpref{wxInitDialogEvent}{wxinitdialogevent}}{A dialog initialisation event} 204\twocolitem{\helpref{wxJoystickEvent}{wxjoystickevent}}{A joystick event} 205\twocolitem{\helpref{wxMenuEvent}{wxmenuevent}}{A menu event} 206\twocolitem{\helpref{wxMouseEvent}{wxmouseevent}}{A mouse event} 207\twocolitem{\helpref{wxMoveEvent}{wxmoveevent}}{A move event} 208\twocolitem{\helpref{wxPaintEvent}{wxpaintevent}}{A paint event} 209\twocolitem{\helpref{wxQueryLayoutInfoEvent}{wxquerylayoutinfoevent}}{Used to query layout information} 210\twocolitem{\helpref{wxSetCursorEvent}{wxsetcursorevent}}{Used for special cursor processing based on current mouse position} 211\twocolitem{\helpref{wxSizeEvent}{wxsizeevent}}{A size event} 212\twocolitem{\helpref{wxScrollWinEvent}{wxscrollwinevent}}{A scroll event sent by a scrolled window (not a scroll bar)} 213\twocolitem{\helpref{wxSysColourChangedEvent}{wxsyscolourchangedevent}}{A system colour change event} 214\end{twocollist} 215 216In some cases, it might be desired by the programmer to get a certain number 217of system events in a parent window, for example all key events sent to, but not 218used by, the native controls in a dialog. In this case, a special event handler 219will have to be written that will override ProcessEvent() in order to pass 220all events (or any selection of them) to the parent window. 221 222 223\subsection{Events generated by the user vs programmatically generated events}\label{progevent} 224 225While generically \helpref{wxEvents}{wxevent} can be generated both by user 226actions (e.g. resize of a \helpref{wxWindow}{wxwindow}) and by calls to functions 227(e.g. \helpref{wxWindow::SetSize}{wxwindowsetsize}), wxWidgets controls 228normally send \helpref{wxCommandEvent}{wxcommandevent}-derived events only for 229the user-generated events. The only {\bf exceptions} to this rule are: 230 231\begin{twocollist}\itemsep=0pt 232\twocolitem{\helpref{wxNotebook::AddPage}{wxnotebookaddpage}}{No event-free alternatives} 233\twocolitem{\helpref{wxNotebook::AdvanceSelection}{wxnotebookadvanceselection}}{No event-free alternatives} 234\twocolitem{\helpref{wxNotebook::DeletePage}{wxnotebookdeletepage}}{No event-free alternatives} 235\twocolitem{\helpref{wxNotebook::SetSelection}{wxnotebooksetselection}}{Use \helpref{wxNotebook::ChangeSelection}{wxnotebookchangeselection} instead, as \helpref{wxNotebook::SetSelection}{wxnotebooksetselection} is deprecated} 236\twocolitem{\helpref{wxTreeCtrl::Delete}{wxtreectrldelete}}{No event-free alternatives} 237\twocolitem{\helpref{wxTreeCtrl::DeleteAllItems}{wxtreectrldeleteallitems}}{No event-free alternatives} 238\twocolitem{\helpref{wxTreeCtrl::EditLabel}{wxtreectrleditlabel}}{No event-free alternatives} 239\twocolitem{All \helpref{wxTextCtrl}{wxtextctrl} methods}{\helpref{wxTextCtrl::ChangeValue}{wxtextctrlchangevalue} can be used instead 240of \helpref{wxTextCtrl::SetValue}{wxtextctrlsetvalue} but the other functions, 241such as \helpref{Replace}{wxtextctrlreplace} or \helpref{WriteText}{wxtextctrlwritetext} 242don't have event-free equivalents} 243\end{twocollist} 244 245 246% VZ: it doesn't work like this, but just in case we ever reenable this 247% behaviour, I leave it here 248% 249% \subsection{Redirection of command events to the window with the focus} 250% 251% The usual upward search through the window hierarchy for command event 252% handlers does not always meet an application's requirements. Say you have two 253% wxTextCtrl windows in a frame, plus a toolbar with Cut, Copy and Paste 254% buttons. To avoid the need to define event handlers in the frame 255% and redirect them explicitly to the window with the focus, command events 256% are sent to the window with the focus first, for 257% menu and toolbar command and UI update events only. This means that 258% each window can handle its own commands and UI updates independently. In 259% fact wxTextCtrl can handle Cut, Copy, Paste, Undo and Redo commands and UI update 260% requests, so no extra coding is required to support them in your menus and 261% toolbars. 262 263\subsection{Pluggable event handlers}\label{pluggablehandlers} 264 265In fact, you don't have to derive a new class from a window class 266if you don't want to. You can derive a new class from wxEvtHandler instead, 267defining the appropriate event table, and then call 268\rtfsp\helpref{wxWindow::SetEventHandler}{wxwindowseteventhandler} (or, preferably, 269\rtfsp\helpref{wxWindow::PushEventHandler}{wxwindowpusheventhandler}) to make this 270event handler the object that responds to events. This way, you can avoid 271a lot of class derivation, and use instances of the same event handler class (but different 272objects as the same event handler object shouldn't be used more than once) to 273handle events from instances of different widget classes. If you ever have to call a window's event handler 274manually, use the GetEventHandler function to retrieve the window's event handler and use that 275to call the member function. By default, GetEventHandler returns a pointer to the window itself 276unless an application has redirected event handling using SetEventHandler or PushEventHandler. 277 278One use of PushEventHandler is to temporarily or permanently change the 279behaviour of the GUI. For example, you might want to invoke a dialog editor 280in your application that changes aspects of dialog boxes. You can 281grab all the input for an existing dialog box, and edit it `in situ', 282before restoring its behaviour to normal. So even if the application 283has derived new classes to customize behaviour, your utility can indulge 284in a spot of body-snatching. It could be a useful technique for on-line 285tutorials, too, where you take a user through a serious of steps and 286don't want them to diverge from the lesson. Here, you can examine the events 287coming from buttons and windows, and if acceptable, pass them through to 288the original event handler. Use PushEventHandler/PopEventHandler 289to form a chain of event handlers, where each handler processes a different 290range of events independently from the other handlers. 291 292\subsection{Window identifiers}\label{windowids} 293 294\index{identifiers}\index{wxID}Window identifiers are integers, and are used to 295uniquely determine window identity in the event system (though you can use it 296for other purposes). In fact, identifiers do not need to be unique 297across your entire application just so long as they are unique within a 298particular context you're interested in, such as a frame and its children. You 299may use the {\tt wxID\_OK} identifier, for example, on any number of dialogs so 300long as you don't have several within the same dialog. 301 302If you pass {\tt wxID\_ANY} to a window constructor, an identifier will be 303generated for you automatically by wxWidgets. This is useful when you don't 304care about the exact identifier either because you're not going to process the 305events from the control being created at all or because you process the events 306from all controls in one place (in which case you should specify {\tt wxID\_ANY} 307in the event table or \helpref{wxEvtHandler::Connect}{wxevthandlerconnect} call 308as well. The automatically generated identifiers are always negative and so 309will never conflict with the user-specified identifiers which must be always 310positive. 311 312The following standard identifiers are supplied. You can use wxID\_HIGHEST to 313determine the number above which it is safe to define your own identifiers. Or, 314you can use identifiers below wxID\_LOWEST. 315 316\begin{verbatim} 317#define wxID_ANY -1 318 319#define wxID_LOWEST 4999 320 321#define wxID_OPEN 5000 322#define wxID_CLOSE 5001 323#define wxID_NEW 5002 324#define wxID_SAVE 5003 325#define wxID_SAVEAS 5004 326#define wxID_REVERT 5005 327#define wxID_EXIT 5006 328#define wxID_UNDO 5007 329#define wxID_REDO 5008 330#define wxID_HELP 5009 331#define wxID_PRINT 5010 332#define wxID_PRINT_SETUP 5011 333#define wxID_PREVIEW 5012 334#define wxID_ABOUT 5013 335#define wxID_HELP_CONTENTS 5014 336#define wxID_HELP_COMMANDS 5015 337#define wxID_HELP_PROCEDURES 5016 338#define wxID_HELP_CONTEXT 5017 339 340#define wxID_CUT 5030 341#define wxID_COPY 5031 342#define wxID_PASTE 5032 343#define wxID_CLEAR 5033 344#define wxID_FIND 5034 345#define wxID_DUPLICATE 5035 346#define wxID_SELECTALL 5036 347#define wxID_DELETE 5037 348#define wxID_REPLACE 5038 349#define wxID_REPLACE_ALL 5039 350#define wxID_PROPERTIES 5040 351 352#define wxID_VIEW_DETAILS 5041 353#define wxID_VIEW_LARGEICONS 5042 354#define wxID_VIEW_SMALLICONS 5043 355#define wxID_VIEW_LIST 5044 356#define wxID_VIEW_SORTDATE 5045 357#define wxID_VIEW_SORTNAME 5046 358#define wxID_VIEW_SORTSIZE 5047 359#define wxID_VIEW_SORTTYPE 5048 360 361#define wxID_FILE1 5050 362#define wxID_FILE2 5051 363#define wxID_FILE3 5052 364#define wxID_FILE4 5053 365#define wxID_FILE5 5054 366#define wxID_FILE6 5055 367#define wxID_FILE7 5056 368#define wxID_FILE8 5057 369#define wxID_FILE9 5058 370 371#define wxID_OK 5100 372#define wxID_CANCEL 5101 373#define wxID_APPLY 5102 374#define wxID_YES 5103 375#define wxID_NO 5104 376#define wxID_STATIC 5105 377 378#define wxID_HIGHEST 5999 379\end{verbatim} 380 381\subsection{Event macros summary}\label{eventmacros} 382 383\wxheading{Macros listed by event class} 384 385The documentation for specific event macros is organised by event class. Please refer 386to these sections for details. 387 388\twocolwidtha{8cm}% 389\begin{twocollist}\itemsep=0pt 390\twocolitem{\helpref{wxActivateEvent}{wxactivateevent}}{The EVT\_ACTIVATE and EVT\_ACTIVATE\_APP macros intercept 391activation and deactivation events.} 392\twocolitem{\helpref{wxCommandEvent}{wxcommandevent}}{A range of commonly-used control events.} 393\twocolitem{\helpref{wxCloseEvent}{wxcloseevent}}{The EVT\_CLOSE macro handles window closure 394called via \helpref{wxWindow::Close}{wxwindowclose}.} 395\twocolitem{\helpref{wxDropFilesEvent}{wxdropfilesevent}}{The EVT\_DROP\_FILES macros handles 396file drop events.} 397\twocolitem{\helpref{wxEraseEvent}{wxeraseevent}}{The EVT\_ERASE\_BACKGROUND macro is used to handle window erase requests.} 398\twocolitem{\helpref{wxFocusEvent}{wxfocusevent}}{The EVT\_SET\_FOCUS and EVT\_KILL\_FOCUS macros are used to handle keyboard focus events.} 399\twocolitem{\helpref{wxKeyEvent}{wxkeyevent}}{EVT\_CHAR, EVT\_KEY\_DOWN and 400EVT\_KEY\_UP macros handle keyboard input for any window.} 401\twocolitem{\helpref{wxIdleEvent}{wxidleevent}}{The EVT\_IDLE macro handle application idle events 402(to process background tasks, for example).} 403\twocolitem{\helpref{wxInitDialogEvent}{wxinitdialogevent}}{The EVT\_INIT\_DIALOG macro is used 404to handle dialog initialisation.} 405\twocolitem{\helpref{wxListEvent}{wxlistevent}}{These macros handle \helpref{wxListCtrl}{wxlistctrl} events.} 406\twocolitem{\helpref{wxMenuEvent}{wxmenuevent}}{These macros handle special menu events (not menu commands).} 407\twocolitem{\helpref{wxMouseEvent}{wxmouseevent}}{Mouse event macros can handle either individual 408mouse events or all mouse events.} 409\twocolitem{\helpref{wxMoveEvent}{wxmoveevent}}{The EVT\_MOVE macro is used to handle a window move.} 410\twocolitem{\helpref{wxPaintEvent}{wxpaintevent}}{The EVT\_PAINT macro is used to handle window paint requests.} 411\twocolitem{\helpref{wxScrollEvent}{wxscrollevent}}{These macros are used to handle scroll events from 412\helpref{wxScrollBar}{wxscrollbar}, \helpref{wxSlider}{wxslider},and \helpref{wxSpinButton}{wxspinbutton}.} 413\twocolitem{\helpref{wxSetCursorEvent}{wxsetcursorevent}}{The EVT\_SET\_CURSOR macro is used for special cursor processing.} 414\twocolitem{\helpref{wxSizeEvent}{wxsizeevent}}{The EVT\_SIZE macro is used to handle a window resize.} 415\twocolitem{\helpref{wxSplitterEvent}{wxsplitterevent}}{The EVT\_SPLITTER\_SASH\_POS\_CHANGED, EVT\_SPLITTER\_UNSPLIT 416and EVT\_SPLITTER\_DCLICK macros are used to handle the various splitter window events.} 417\twocolitem{\helpref{wxSysColourChangedEvent}{wxsyscolourchangedevent}}{The EVT\_SYS\_COLOUR\_CHANGED macro is used to handle 418events informing the application that the user has changed the system colours (Windows only).} 419\twocolitem{\helpref{wxTreeEvent}{wxtreeevent}}{These macros handle \helpref{wxTreeCtrl}{wxtreectrl} events.} 420\twocolitem{\helpref{wxUpdateUIEvent}{wxupdateuievent}}{The EVT\_UPDATE\_UI macro is used to handle user interface 421update pseudo-events, which are generated to give the application the chance to update the visual state of menus, 422toolbars and controls.} 423\end{twocollist} 424 425\subsection{Custom event summary}\label{customevents} 426 427\wxheading{General approach} 428 429Since version 2.2.x of wxWidgets, each event type is identified by ID which 430is given to the event type {\it at runtime} which makes it possible to add 431new event types to the library or application without risking ID clashes 432(two different event types mistakingly getting the same event ID). This 433event type ID is stored in a struct of type {\bf const wxEventType}. 434 435In order to define a new event type, there are principally two choices. 436One is to define a entirely new event class (typically deriving from 437\helpref{wxEvent}{wxevent} or \helpref{wxCommandEvent}{wxcommandevent}. 438The other is to use the existing event classes and give them an new event 439type. You'll have to define and declare a new event type using either way, 440and this is done using the following macros: 441 442\begin{verbatim} 443// in the header of the source file 444BEGIN_DECLARE_EVENT_TYPES() 445DECLARE_EVENT_TYPE(name, value) 446END_DECLARE_EVENT_TYPES() 447 448// in the implementation 449DEFINE_EVENT_TYPE(name) 450\end{verbatim} 451 452You can ignore the {\it value} parameter of the DECLARE\_EVENT\_TYPE macro 453since it used only for backwards compatibility with wxWidgets 2.0.x based 454applications where you have to give the event type ID an explicit value. 455 456See also the \helpref{event sample}{sampleevent} for an example of code 457defining and working with the custom event types. 458 459\wxheading{Using existing event classes} 460 461If you just want to use a \helpref{wxCommandEvent}{wxcommandevent} with 462a new event type, you can then use one of the generic event table macros 463listed below, without having to define a new macro yourself. This also 464has the advantage that you won't have to define a new \helpref{wxEvent::Clone()}{wxeventclone} 465method for posting events between threads etc. This could look like this 466in your code: 467 468{\small% 469\begin{verbatim} 470DECLARE_EVENT_TYPE(wxEVT_MY_EVENT, -1) 471 472DEFINE_EVENT_TYPE(wxEVT_MY_EVENT) 473 474// user code intercepting the event 475 476BEGIN_EVENT_TABLE(MyFrame, wxFrame) 477 EVT_MENU (wxID_EXIT, MyFrame::OnExit) 478 // .... 479 EVT_COMMAND (ID_MY_WINDOW, wxEVT_MY_EVENT, MyFrame::OnMyEvent) 480END_EVENT_TABLE() 481 482void MyFrame::OnMyEvent( wxCommandEvent &event ) 483{ 484 // do something 485 wxString text = event.GetText(); 486} 487 488 489// user code sending the event 490 491void MyWindow::SendEvent() 492{ 493 wxCommandEvent event( wxEVT_MY_EVENT, GetId() ); 494 event.SetEventObject( this ); 495 // Give it some contents 496 event.SetText( wxT("Hallo") ); 497 // Send it 498 GetEventHandler()->ProcessEvent( event ); 499} 500\end{verbatim} 501}% 502 503 504\wxheading{Generic event table macros} 505 506\twocolwidtha{8cm}% 507\begin{twocollist}\itemsep=0pt 508\twocolitem{\windowstyle{EVT\_CUSTOM(event, id, func)}}{Allows you to add a custom event table 509entry by specifying the event identifier (such as wxEVT\_SIZE), the window identifier, 510and a member function to call.} 511\twocolitem{\windowstyle{EVT\_CUSTOM\_RANGE(event, id1, id2, func)}}{The same as EVT\_CUSTOM, 512but responds to a range of window identifiers.} 513\twocolitem{\windowstyle{EVT\_COMMAND(id, event, func)}}{The same as EVT\_CUSTOM, but 514expects a member function with a wxCommandEvent argument.} 515\twocolitem{\windowstyle{EVT\_COMMAND\_RANGE(id1, id2, event, func)}}{The same as EVT\_CUSTOM\_RANGE, but 516expects a member function with a wxCommandEvent argument.} 517\twocolitem{\windowstyle{EVT\_NOTIFY(event, id, func)}}{The same as EVT\_CUSTOM, but 518expects a member function with a wxNotifyEvent argument.} 519\twocolitem{\windowstyle{EVT\_NOTIFY\_RANGE(event, id1, id2, func)}}{The same as EVT\_CUSTOM\_RANGE, but 520expects a member function with a wxNotifyEvent argument.} 521\end{twocollist} 522 523 524\wxheading{Defining your own event class} 525 526Under certain circumstances, it will be required to define your own event 527class e.g. for sending more complex data from one place to another. Apart 528from defining your event class, you will also need to define your own 529event table macro (which is quite long). Watch out to put in enough 530casts to the inherited event function. Here is an example, taken mostly 531from the {\it wxPlot} library, which is in the {\it contrib} section of 532the wxWidgets sources. 533 534{\small% 535\begin{verbatim} 536 537// code defining event 538 539class wxPlotEvent: public wxNotifyEvent 540{ 541public: 542 wxPlotEvent( wxEventType commandType = wxEVT_NULL, int id = 0 ); 543 544 // accessors 545 wxPlotCurve *GetCurve() 546 { return m_curve; } 547 548 // required for sending with wxPostEvent() 549 wxEvent* Clone(); 550 551private: 552 wxPlotCurve *m_curve; 553}; 554 555DECLARE_EVENT_TYPE( wxEVT_PLOT_ACTION, -1 ) 556 557typedef void (wxEvtHandler::*wxPlotEventFunction)(wxPlotEvent&); 558 559#define EVT_PLOT(id, fn) \ 560 DECLARE_EVENT_TABLE_ENTRY( wxEVT_PLOT_ACTION, id, -1, \ 561 (wxObjectEventFunction) (wxEventFunction) (wxCommandEventFunction) (wxNotifyEventFunction) \ 562 wxStaticCastEvent( wxPlotEventFunction, & fn ), (wxObject *) NULL ), 563 564 565// code implementing the event type and the event class 566 567DEFINE_EVENT_TYPE( wxEVT_PLOT_ACTION ) 568 569wxPlotEvent::wxPlotEvent( ... 570 571 572// user code intercepting the event 573 574BEGIN_EVENT_TABLE(MyFrame, wxFrame) 575 EVT_PLOT (ID_MY_WINDOW, MyFrame::OnPlot) 576END_EVENT_TABLE() 577 578void MyFrame::OnPlot( wxPlotEvent &event ) 579{ 580 wxPlotCurve *curve = event.GetCurve(); 581} 582 583 584// user code sending the event 585 586void MyWindow::SendEvent() 587{ 588 wxPlotEvent event( wxEVT_PLOT_ACTION, GetId() ); 589 event.SetEventObject( this ); 590 event.SetCurve( m_curve ); 591 GetEventHandler()->ProcessEvent( event ); 592} 593 594\end{verbatim} 595}% 596 597