Classes: \helpref{wxEvtHandler}{wxevthandler}, \helpref{wxWindow}{wxwindow}, \helpref{wxEvent}{wxevent}
-\subsection{Introduction}
+\subsection{Introduction}\label{eventintroduction}
-Before version 2.0 of wxWindows, events were handled by the application
+Before version 2.0 of wxWidgets, events were handled by the application
either by supplying callback functions, or by overriding virtual member
functions such as {\bf OnSize}.
-From wxWindows 2.0, {\it event tables} are used instead, with a few exceptions.
+From wxWidgets 2.0, {\it event tables} are used instead, with a few exceptions.
-An event table is placed in an implementation file to tell wxWindows how to map
+An event table is placed in an implementation file to tell wxWidgets how to map
events to member functions. These member functions are not virtual functions, but
they are all similar in form: they take a single wxEvent-derived argument, and have a void return
type.
\subsection{How events are processed}\label{eventprocessing}
-When an event is received from the windowing system, wxWindows calls
+When an event is received from the windowing system, wxWidgets calls
\helpref{wxEvtHandler::ProcessEvent}{wxevthandlerprocessevent} on the first
event handler object belonging to the window generating the event.
-It may be noted that wxWindows' event processing system implements something
+It may be noted that wxWidgets' event processing system implements something
very close to virtual methods in normal C++, i.e. it is possible to alter
the behaviour of a class by overriding its event handling functions. In
many cases this works even for changing the behaviour of native controls.
if ( isalpha( event.KeyCode() ) )
{
// key code is within legal range. we call event.Skip() so the
- // event can be processed either in the base wxWindows class
+ // event can be processed either in the base wxWidgets class
// or the native control.
event.Skip();
\end{enumerate}
{\bf Pay close attention to Step 5.} People often overlook or get
-confused by this powerful feature of the wxWindows event processing
+confused by this powerful feature of the wxWidgets event processing
system. To put it a different way, events set to propagate
(\helpref{See: wxEvent::ShouldPropagate}{wxeventshouldpropagate})
(most likely derived either directly or indirectly from wxCommandEvent)
doesn't call \helpref{event.Skip()}{wxeventskip}.
Finally, there is another additional complication (which, in fact, simplifies
-life of wxWindows programmers significantly): when propagating the command
+life of wxWidgets programmers significantly): when propagating the command
events upwards to the parent window, the event propagation stops when it
reaches the parent dialog, if any. This means that you don't risk to get
unexpected events from the dialog controls (which might be left unprocessed by
and their parent-child relation are well understood by the programmer while it
may be very difficult, if not impossible, to track down all the dialogs which
may be popped up in a complex program (remember that some are created
-automatically by wxWindows). If you need to specify a different behaviour for
+automatically by wxWidgets). If you need to specify a different behaviour for
some reason, you can use
\helpref{SetExtraStyle(wxWS\_EX\_BLOCK\_EVENTS)}{wxwindowsetextrastyle}
explicitly to prevent the events from being propagated beyond the given window
instead of using the slower run-time type system.
As mentioned above, only command events are recursively applied to the parents event
-handler in the libary itself. As this quite often causes confusion for users,
+handler in the library itself. As this quite often causes confusion for users,
here is a list of system events which will NOT get sent to the parent's event handler:
\begin{twocollist}\itemsep=0pt
\twocolitem{\helpref{wxMoveEvent}{wxmoveevent}}{A move event}
\twocolitem{\helpref{wxPaintEvent}{wxpaintevent}}{A paint event}
\twocolitem{\helpref{wxQueryLayoutInfoEvent}{wxquerylayoutinfoevent}}{Used to query layout information}
+\twocolitem{\helpref{wxSetCursorEvent}{wxsetcursorevent}}{Used for special cursor processing based on current mouse position}
\twocolitem{\helpref{wxSizeEvent}{wxsizeevent}}{A size event}
\twocolitem{\helpref{wxScrollWinEvent}{wxscrollwinevent}}{A scroll event sent by a scrolled window (not a scroll bar)}
\twocolitem{\helpref{wxSysColourChangedEvent}{wxsyscolourchangedevent}}{A system colour change event}
-\twocolitem{\helpref{wxUpdateUIEvent}{wxupdateuievent}}{A user interface update event}
\end{twocollist}
In some cases, it might be desired by the programmer to get a certain number
will have to be written that will override ProcessEvent() in order to pass
all events (or any selection of them) to the parent window.
+
+\subsection{Events generated by the user vs programmatically generated events}\label{progevent}
+
+While generically \helpref{wxEvents}{wxevent} can be generated both by user
+actions (e.g. resize of a \helpref{wxWindow}{wxwindow}) and by calls to functions
+(e.g. \helpref{wxWindow::SetSize}{wxwindowsetsize}), wxWidgets controls
+normally send \helpref{wxCommandEvent}{wxcommandevent}-derived events only for
+the user-generated events. The only {\bf exceptions} to this rule are:
+
+\begin{twocollist}\itemsep=0pt
+\twocolitem{\helpref{wxNotebook::AddPage}{wxnotebookaddpage}}{No event-free alternatives}
+\twocolitem{\helpref{wxNotebook::AdvanceSelection}{wxnotebookadvanceselection}}{No event-free alternatives}
+\twocolitem{\helpref{wxNotebook::DeletePage}{wxnotebookdeletepage}}{No event-free alternatives}
+\twocolitem{\helpref{wxNotebook::SetSelection}{wxnotebooksetselection}}{Use \helpref{wxNotebook::ChangeSelection}{wxnotebookchangeselection} instead, as \helpref{wxNotebook::SetSelection}{wxnotebooksetselection} is deprecated}
+\twocolitem{\helpref{wxTreeCtrl::Delete}{wxtreectrldelete}}{No event-free alternatives}
+\twocolitem{\helpref{wxTreeCtrl::DeleteAllItems}{wxtreectrldeleteallitems}}{No event-free alternatives}
+\twocolitem{\helpref{wxTreeCtrl::EditLabel}{wxtreectrleditlabel}}{No event-free alternatives}
+\twocolitem{All \helpref{wxTextCtrl}{wxtextctrl} methods}{\helpref{wxTextCtrl::ChangeValue}{wxtextctrlchangevalue} can be used instead
+of \helpref{wxTextCtrl::SetValue}{wxtextctrlsetvalue} but the other functions,
+such as \helpref{Replace}{wxtextctrlreplace} or \helpref{WriteText}{wxtextctrlwritetext}
+don't have event-free equivalents}
+\end{twocollist}
+
+
% VZ: it doesn't work like this, but just in case we ever reenable this
% behaviour, I leave it here
%
% requests, so no extra coding is required to support them in your menus and
% toolbars.
-\subsection{Pluggable event handlers}
+\subsection{Pluggable event handlers}\label{pluggablehandlers}
In fact, you don't have to derive a new class from a window class
if you don't want to. You can derive a new class from wxEvtHandler instead,
\rtfsp\helpref{wxWindow::SetEventHandler}{wxwindowseteventhandler} (or, preferably,
\rtfsp\helpref{wxWindow::PushEventHandler}{wxwindowpusheventhandler}) to make this
event handler the object that responds to events. This way, you can avoid
-a lot of class derivation, and use the same event handler object to
-handle events from instances of different classes. If you ever have to call a window's event handler
+a lot of class derivation, and use instances of the same event handler class (but different
+objects as the same event handler object shouldn't be used more than once) to
+handle events from instances of different widget classes. If you ever have to call a window's event handler
manually, use the GetEventHandler function to retrieve the window's event handler and use that
to call the member function. By default, GetEventHandler returns a pointer to the window itself
unless an application has redirected event handling using SetEventHandler or PushEventHandler.
long as you don't have several within the same dialog.
If you pass {\tt wxID\_ANY} to a window constructor, an identifier will be
-generated for you automatically by wxWindows. This is useful when you don't
+generated for you automatically by wxWidgets. This is useful when you don't
care about the exact identifier either because you're not going to process the
events from the control being created at all or because you process the events
from all controls in one place (in which case you should specify {\tt wxID\_ANY}
\subsection{Event macros summary}\label{eventmacros}
-\wxheading{Generic event table macros}
-
-\twocolwidtha{8cm}%
-\begin{twocollist}\itemsep=0pt
-\twocolitem{\windowstyle{EVT\_CUSTOM(event, id, func)}}{Allows you to add a custom event table
-entry by specifying the event identifier (such as wxEVT\_SIZE), the window identifier,
-and a member function to call.}
-\twocolitem{\windowstyle{EVT\_CUSTOM\_RANGE(event, id1, id2, func)}}{The same as EVT\_CUSTOM,
-but responds to a range of window identifiers.}
-\twocolitem{\windowstyle{EVT\_COMMAND(id, event, func)}}{The same as EVT\_CUSTOM, but
-expects a member function with a wxCommandEvent argument.}
-\twocolitem{\windowstyle{EVT\_COMMAND\_RANGE(id1, id2, event, func)}}{The same as EVT\_CUSTOM\_RANGE, but
-expects a member function with a wxCommandEvent argument.}
-\end{twocollist}
-
\wxheading{Macros listed by event class}
The documentation for specific event macros is organised by event class. Please refer
\twocolitem{\helpref{wxPaintEvent}{wxpaintevent}}{The EVT\_PAINT macro is used to handle window paint requests.}
\twocolitem{\helpref{wxScrollEvent}{wxscrollevent}}{These macros are used to handle scroll events from
\helpref{wxScrollBar}{wxscrollbar}, \helpref{wxSlider}{wxslider},and \helpref{wxSpinButton}{wxspinbutton}.}
+\twocolitem{\helpref{wxSetCursorEvent}{wxsetcursorevent}}{The EVT\_SET\_CURSOR macro is used for special cursor processing.}
\twocolitem{\helpref{wxSizeEvent}{wxsizeevent}}{The EVT\_SIZE macro is used to handle a window resize.}
\twocolitem{\helpref{wxSplitterEvent}{wxsplitterevent}}{The EVT\_SPLITTER\_SASH\_POS\_CHANGED, EVT\_SPLITTER\_UNSPLIT
and EVT\_SPLITTER\_DCLICK macros are used to handle the various splitter window events.}
toolbars and controls.}
\end{twocollist}
+\subsection{Custom event summary}\label{customevents}
+
+\wxheading{General approach}
+
+Since version 2.2.x of wxWidgets, each event type is identified by ID which
+is given to the event type {\it at runtime} which makes it possible to add
+new event types to the library or application without risking ID clashes
+(two different event types mistakingly getting the same event ID). This
+event type ID is stored in a struct of type {\bf const wxEventType}.
+
+In order to define a new event type, there are principally two choices.
+One is to define a entirely new event class (typically deriving from
+\helpref{wxEvent}{wxevent} or \helpref{wxCommandEvent}{wxcommandevent}.
+The other is to use the existing event classes and give them an new event
+type. You'll have to define and declare a new event type using either way,
+and this is done using the following macros:
+
+\begin{verbatim}
+// in the header of the source file
+BEGIN_DECLARE_EVENT_TYPES()
+DECLARE_EVENT_TYPE(name, value)
+END_DECLARE_EVENT_TYPES()
+
+// in the implementation
+DEFINE_EVENT_TYPE(name)
+\end{verbatim}
+
+You can ignore the {\it value} parameter of the DECLARE\_EVENT\_TYPE macro
+since it is used only for backwards compatibility with wxWidgets 2.0.x based
+applications where you have to give the event type ID an explicit value.
+
+See also the \helpref{event sample}{sampleevent} for an example of code
+defining and working with the custom event types.
+
+\wxheading{Using existing event classes}
+
+If you just want to use a \helpref{wxCommandEvent}{wxcommandevent} with
+a new event type, you can then use one of the generic event table macros
+listed below, without having to define a new macro yourself. This also
+has the advantage that you won't have to define a new \helpref{wxEvent::Clone()}{wxeventclone}
+method for posting events between threads etc. This could look like this
+in your code:
+
+{\small%
+\begin{verbatim}
+DECLARE_EVENT_TYPE(wxEVT_MY_EVENT, -1)
+
+DEFINE_EVENT_TYPE(wxEVT_MY_EVENT)
+
+// user code intercepting the event
+
+BEGIN_EVENT_TABLE(MyFrame, wxFrame)
+ EVT_MENU (wxID_EXIT, MyFrame::OnExit)
+ // ....
+ EVT_COMMAND (ID_MY_WINDOW, wxEVT_MY_EVENT, MyFrame::OnMyEvent)
+END_EVENT_TABLE()
+
+void MyFrame::OnMyEvent( wxCommandEvent &event )
+{
+ // do something
+ wxString text = event.GetText();
+}
+
+
+// user code sending the event
+
+void MyWindow::SendEvent()
+{
+ wxCommandEvent event( wxEVT_MY_EVENT, GetId() );
+ event.SetEventObject( this );
+ // Give it some contents
+ event.SetText( wxT("Hallo") );
+ // Send it
+ GetEventHandler()->ProcessEvent( event );
+}
+\end{verbatim}
+}%
+
+
+\wxheading{Generic event table macros}
+
+\twocolwidtha{8cm}%
+\begin{twocollist}\itemsep=0pt
+\twocolitem{\windowstyle{EVT\_CUSTOM(event, id, func)}}{Allows you to add a custom event table
+entry by specifying the event identifier (such as wxEVT\_SIZE), the window identifier,
+and a member function to call.}
+\twocolitem{\windowstyle{EVT\_CUSTOM\_RANGE(event, id1, id2, func)}}{The same as EVT\_CUSTOM,
+but responds to a range of window identifiers.}
+\twocolitem{\windowstyle{EVT\_COMMAND(id, event, func)}}{The same as EVT\_CUSTOM, but
+expects a member function with a wxCommandEvent argument.}
+\twocolitem{\windowstyle{EVT\_COMMAND\_RANGE(id1, id2, event, func)}}{The same as EVT\_CUSTOM\_RANGE, but
+expects a member function with a wxCommandEvent argument.}
+\twocolitem{\windowstyle{EVT\_NOTIFY(event, id, func)}}{The same as EVT\_CUSTOM, but
+expects a member function with a wxNotifyEvent argument.}
+\twocolitem{\windowstyle{EVT\_NOTIFY\_RANGE(event, id1, id2, func)}}{The same as EVT\_CUSTOM\_RANGE, but
+expects a member function with a wxNotifyEvent argument.}
+\end{twocollist}
+
+
+\wxheading{Defining your own event class}
+
+Under certain circumstances, it will be required to define your own event
+class e.g. for sending more complex data from one place to another. Apart
+from defining your event class, you will also need to define your own
+event table macro (which is quite long). Watch out to put in enough
+casts to the inherited event function. Here is an example:
+
+{\small%
+\begin{verbatim}
+
+// code defining event
+
+class wxPlotEvent: public wxNotifyEvent
+{
+public:
+ wxPlotEvent( wxEventType commandType = wxEVT_NULL, int id = 0 );
+
+ // accessors
+ wxPlotCurve *GetCurve()
+ { return m_curve; }
+
+ // required for sending with wxPostEvent()
+ virtual wxEvent *Clone() const;
+
+private:
+ wxPlotCurve *m_curve;
+};
+
+DECLARE_EVENT_TYPE( wxEVT_PLOT_ACTION, -1 )
+
+typedef void (wxEvtHandler::*wxPlotEventFunction)(wxPlotEvent&);
+
+#define EVT_PLOT(id, fn) \
+ DECLARE_EVENT_TABLE_ENTRY( wxEVT_PLOT_ACTION, id, -1, \
+ (wxObjectEventFunction) (wxEventFunction) (wxCommandEventFunction) (wxNotifyEventFunction) \
+ wxStaticCastEvent( wxPlotEventFunction, & fn ), (wxObject *) NULL ),
+
+
+// code implementing the event type and the event class
+
+DEFINE_EVENT_TYPE( wxEVT_PLOT_ACTION )
+
+wxPlotEvent::wxPlotEvent( ...
+
+
+// user code intercepting the event
+
+BEGIN_EVENT_TABLE(MyFrame, wxFrame)
+ EVT_PLOT (ID_MY_WINDOW, MyFrame::OnPlot)
+END_EVENT_TABLE()
+
+void MyFrame::OnPlot( wxPlotEvent &event )
+{
+ wxPlotCurve *curve = event.GetCurve();
+}
+
+
+// user code sending the event
+
+void MyWindow::SendEvent()
+{
+ wxPlotEvent event( wxEVT_PLOT_ACTION, GetId() );
+ event.SetEventObject( this );
+ event.SetCurve( m_curve );
+ GetEventHandler()->ProcessEvent( event );
+}
+
+\end{verbatim}
+}%
+
projects / wxWidgets.git / blobdiff