// Licence: wxWindows license
/////////////////////////////////////////////////////////////////////////////
-/*!
+/**
+
+@page overview_events Events and Event Handling
+
+Related classes: wxEvtHandler, wxWindow, wxEvent
+
+@li @ref overview_events_introduction
+@li @ref overview_events_eventhandling
+@li @ref overview_events_processing
+@li @ref overview_events_custom
+@li @ref overview_events_misc
+
+
+<hr>
+
+
+@section overview_events_introduction Introduction to Events
+
+Like with all the other GUI frameworks, the control of flow in wxWidgets
+applications is event-based: the program normally performs most of its actions
+in response to the events generated by the user. These events can be triggered
+by using the input devices (such as keyboard, mouse, joystick) directly or,
+more commonly, by a standard control which synthesizes such input events into
+higher level events: for example, a wxButton can generate a click event when
+the user presses the left mouse button on it and then releases it without
+pressing @c Esc in the meanwhile. There are also events which don't directly
+correspond to the user actions, such as wxTimerEvent or wxSocketEvent.
+
+But in all cases wxWidgets represents these events in a uniform way and allows
+you to handle them in the same way wherever they originate from. And while the
+events are normally generated by wxWidgets itself, you can also do this, which
+is especially useful when using custom events (see @ref overview_events_custom).
+
+To be more precise, each event is described by:
+ - <em>Event type</em>: this is simply a value of type wxEventType which
+ uniquely identifies the type of the event. For example, clicking on a button,
+ selecting an item from a list box and pressing a key on the keyboard all
+ generate events with different event types.
+ - <em>Event class</em> carried by the event: each event has some information
+ associated with it and this data is represented by an object of a class
+ derived from wxEvent. Events of different types can use the same event class,
+ for example both button click and listbox selection events use wxCommandEvent
+ class (as do all the other simple control events), but the key press event
+ uses wxKeyEvent as the information associated with it is different.
+ - <em>Event source</em>: wxEvent stores the object which generated the event
+ and, for windows, its identifier (see @ref overview_events_winid). As it is
+ common to have more than one object generating events of the same type (e.g. a
+ typical window contains several buttons, all generating the same button click
+ event), checking the event source object or its id allows to distinguish
+ between them.
+
+
+@section overview_events_eventhandling Event Handling
+
+There are two principal ways to handle events in wxWidgets. One of them uses
+<em>event table</em> macros and allows you to define the binding between events
+and their handlers only statically, i.e., during program compilation. The other
+one uses wxEvtHandler::Bind<>() call and can be used to bind and
+unbind, the handlers dynamically, i.e. during run-time depending on some
+conditions. It also allows the direct binding of events to:
+@li A handler method in another object.
+@li An ordinary function like a static method or a global function.
+@li An arbitrary functor like boost::function<>.
+
+The static event tables can only handle events in the object where they are
+defined so using Bind<>() is more flexible than using the event tables. On the
+other hand, event tables are more succinct and centralize all event handler
+bindings in one place. You can either choose a single approach that you find
+preferable or freely combine both methods in your program in different classes
+or even in one and the same class, although this is probably sufficiently
+confusing to be a bad idea.
+
+Also notice that most of the existing wxWidgets tutorials and discussions use
+the event tables because they historically preceded the apparition of dynamic
+event handling in wxWidgets. But this absolutely doesn't mean that using the
+event tables is the preferred way: handling events dynamically is better in
+several aspects and you should strongly consider doing it if you are just
+starting with wxWidgets. On the other hand, you still need to know about the
+event tables if only because you are going to see them in many samples and
+examples.
+
+So before you make the choice between static event tables and dynamically
+connecting the event handlers, let us discuss these two ways in more detail. In
+the next section we provide a short introduction to handling the events using
+the event tables. Please see @ref overview_events_bind for the discussion of
+Bind<>().
+
+@subsection overview_events_eventtables Event Handling with Event Tables
+
+To use an <em>event table</em> you must first decide in which class you wish to
+handle the events. The only requirement imposed by wxWidgets is that this class
+must derive from wxEvtHandler and so, considering that wxWindow derives from
+it, any classes representing windows can handle events. Simple events such as
+menu commands are usually processed at the level of a top-level window
+containing the menu, so let's suppose that you need to handle some events in @c
+MyFrame class deriving from wxFrame.
+
+First define one or more <em>event handlers</em>. They
+are just simple methods of the class that take as a parameter a
+reference to an object of a wxEvent-derived class and have no return value (any
+return information is passed via the argument, which is why it is non-const).
+You also need to insert a macro
+
+@code
+DECLARE_EVENT_TABLE()
+@endcode
+
+somewhere in the class declaration. It doesn't matter where it appears but
+it's customary to put it at the end because the macro changes the access
+type internally so it's safest if nothing follows it. The
+full class declaration might look like this:
+
+@code
+class MyFrame : public wxFrame
+{
+public:
+ MyFrame(...) : wxFrame(...) { }
+
+ ...
+
+protected:
+ int m_whatever;
+
+private:
+ // Notice that as the event handlers normally are not called from outside
+ // the class, they normally are private. In particular they don't need
+ // to be public.
+ void OnExit(wxCommandEvent& event);
+ void OnButton1(wxCommandEvent& event);
+ void OnSize(wxSizeEvent& event);
+
+ // it's common to call the event handlers OnSomething() but there is no
+ // obligation to do that; this one is an event handler too:
+ void DoTest(wxCommandEvent& event);
+
+ DECLARE_EVENT_TABLE()
+};
+@endcode
+
+Next the event table must be defined and, as with any definition, it must be
+placed in an implementation file. The event table tells wxWidgets how to map
+events to member functions and in our example it could look like this:
+
+@code
+BEGIN_EVENT_TABLE(MyFrame, wxFrame)
+ EVT_MENU(wxID_EXIT, MyFrame::OnExit)
+ EVT_MENU(DO_TEST, MyFrame::DoTest)
+ EVT_SIZE(MyFrame::OnSize)
+ EVT_BUTTON(BUTTON1, MyFrame::OnButton1)
+END_EVENT_TABLE()
+@endcode
+
+Notice that you must mention a method you want to use for the event handling in
+the event table definition; just defining it in MyFrame class is @e not enough.
+
+Let us now look at the details of this definition: the first line means that we
+are defining the event table for MyFrame class and that its base class is
+wxFrame, so events not processed by MyFrame will, by default, be handled by
+wxFrame. The next four lines define bindings of individual events to their
+handlers: the first two of them map menu commands from the items with the
+identifiers specified as the first macro parameter to two different member
+functions. In the next one, @c EVT_SIZE means that any changes in the size of
+the frame will result in calling OnSize() method. Note that this macro doesn't
+need a window identifier, since normally you are only interested in the current
+window's size events.
+
+The @c EVT_BUTTON macro demonstrates that the originating event does not have to
+come from the window class implementing the event table -- if the event source
+is a button within a panel within a frame, this will still work, because event
+tables are searched up through the hierarchy of windows for the command events.
+(But only command events, so you can't catch mouse move events in a child
+control in the parent window in the same way because wxMouseEvent doesn't
+derive from wxCommandEvent. See below for how you can do it.) In this case, the
+button's event table will be searched, then the parent panel's, then the
+frame's.
+
+Finally, you need to implement the event handlers. As mentioned before, all
+event handlers take a wxEvent-derived argument whose exact class differs
+according to the type of event and the class of the originating window. For
+size events, wxSizeEvent is used. For menu commands and most control commands
+(such as button presses), wxCommandEvent is used. When controls get more
+complicated, more specific wxCommandEvent-derived event classes providing
+additional control-specific information can be used, such as wxTreeEvent for
+events from wxTreeCtrl windows.
+
+In the simplest possible case an event handler may not use the @c event
+parameter at all. For example,
+
+@code
+void MyFrame::OnExit(wxCommandEvent& WXUNUSED(event))
+{
+ // when the user selects "Exit" from the menu we should close
+ Close(true);
+}
+@endcode
+
+In other cases you may need some information carried by the @c event argument,
+as in:
+
+@code
+void MyFrame::OnSize(wxSizeEvent& event)
+{
+ wxSize size = event.GetSize();
+
+ ... update the frame using the new size ...
+}
+@endcode
+
+You will find the details about the event table macros and the corresponding
+wxEvent-derived classes in the discussion of each control generating these
+events.
+
+
+@subsection overview_events_bind Dynamic Event Handling
+
+The possibilities of handling events in this way are rather different.
+Let us start by looking at the syntax: the first obvious difference is that you
+need not use DECLARE_EVENT_TABLE() nor BEGIN_EVENT_TABLE() and the
+associated macros. Instead, in any place in your code, but usually in
+the code of the class defining the handler itself (and definitely not in the
+global scope as with the event tables), call its Bind<>() method like this:
+
+@code
+MyFrame::MyFrame(...)
+{
+ Bind(wxEVT_COMMAND_MENU_SELECTED, &MyFrame::OnExit, this, wxID_EXIT);
+}
+@endcode
+
+Note that @c this pointer must be specified here.
+
+Now let us describe the semantic differences:
+<ul>
+ <li>
+ Event handlers can be bound at any moment. For example, it's possible
+ to do some initialization first and only bind the handlers if and when
+ it succeeds. This can avoid the need to test that the object was properly
+ initialized in the event handlers themselves. With Bind<>() they
+ simply won't be called if it wasn't correctly initialized.
+ </li>
+
+ <li>
+ As a slight extension of the above, the handlers can also be unbound at
+ any time with Unbind<>() (and maybe rebound later). Of course,
+ it's also possible to emulate this behaviour with the classic
+ static (i.e., bound via event tables) handlers by using an internal
+ flag indicating whether the handler is currently enabled and returning
+ from it if it isn't, but using dynamically bind handlers requires
+ less code and is also usually more clear.
+ </li>
+
+ <li>
+ Almost last but very, very far from least is the increased flexibility
+ which allows to bind an event to:
+ @li A method in another object.
+ @li An ordinary function like a static method or a global function.
+ @li An arbitrary functor like boost::function<>.
+
+ This is impossible to do with the event tables because it is not
+ possible to specify these handlers to dispatch the event to, so it
+ necessarily needs to be sent to the same object which generated the
+ event. Not so with Bind<>() which can be used to specify these handlers
+ which will handle the event. To give a quick example, a common question
+ is how to receive the mouse movement events happening when the mouse is
+ in one of the frame children in the frame itself. Doing it in a naive
+ way doesn't work:
+ <ul>
+ <li>
+ A @c EVT_LEAVE_WINDOW(MyFrame::OnMouseLeave) line in the frame
+ event table has no effect as mouse move (including entering and
+ leaving) events are not propagated up to the parent window
+ (at least not by default).
+ </li>
+
+ <li>
+ Putting the same line in a child event table will crash during
+ run-time because the MyFrame method will be called on a wrong
+ object -- it's easy to convince oneself that the only object
+ that can be used here is the pointer to the child, as
+ wxWidgets has nothing else. But calling a frame method with the
+ child window pointer instead of the pointer to the frame is, of
+ course, disastrous.
+ </li>
+ </ul>
+
+ However writing
+ @code
+ MyFrame::MyFrame(...)
+ {
+ m_child->Bind(wxEVT_LEAVE_WINDOW, &MyFrame::OnMouseLeave, this);
+ }
+ @endcode
+ will work exactly as expected. Note that you can get the object that
+ generated the event -- and that is not the same as the frame -- via
+ wxEvent::GetEventObject() method of @c event argument passed to the
+ event handler.
+ </li>
+
+ <li>
+ Really last point is the consequence of the previous one: because of
+ increased flexibility of Bind(), it is also safer as it is impossible
+ to accidentally use a method of another class. Instead of run-time
+ crashes you will get compilation errors in this case when using Bind().
+ </li>
+</ul>
+
+Let us now look at more examples of how to use different event handlers using
+the two overloads of Bind() function: first one for the object methods and the
+other one for arbitrary functors (callable objects, including simple functions):
+
+In addition to using a method of the object generating the event itself, you
+can use a method from a completely different object as an event handler:
+
+@code
+void MyFrameHandler::OnFrameExit( wxCommandEvent & )
+{
+ // Do something useful.
+}
+
+MyFrameHandler myFrameHandler;
+
+MyFrame::MyFrame()
+{
+ Bind( wxEVT_COMMAND_MENU_SELECTED, &MyFrameHandler::OnFrameExit,
+ &myFrameHandler, wxID_EXIT );
+}
+@endcode
+
+Note that @c MyFrameHandler doesn't need to derive from wxEvtHandler. But
+keep in mind that then the lifetime of @c myFrameHandler must be greater than
+that of @c MyFrame object -- or at least it needs to be unbound before being
+destroyed.
+
+
+To use an ordinary function or a static method as an event handler you would
+write something like this:
+
+@code
+void HandleExit( wxCommandEvent & )
+{
+ // Do something useful
+}
+
+MyFrame::MyFrame()
+{
+ Bind( wxEVT_COMMAND_MENU_SELECTED, &HandleExit, wxID_EXIT );
+}
+@endcode
+
+And finally you can bind to an arbitrary functor and use it as an event
+handler:
+
+@code
+
+struct MyFunctor
+{
+ void operator()( wxCommandEvent & )
+ {
+ // Do something useful
+ }
+};
+
+MyFunctor myFunctor;
+
+MyFrame::MyFrame()
+{
+ Bind( wxEVT_COMMAND_MENU_SELECTED, &myFunctor, wxID_EXIT );
+}
+@endcode
+
+A common example of a functor is boost::function<>:
+
+@code
+using namespace boost;
+
+void MyHandler::OnExit( wxCommandEvent & )
+{
+ // Do something useful
+}
+
+MyHandler myHandler;
+
+MyFrame::MyFrame()
+{
+ function< void ( wxCommandEvent & ) > exitHandler( bind( &MyHandler::OnExit, &myHandler, _1 ));
+
+ Bind( wxEVT_COMMAND_MENU_SELECTED, exitHandler, wxID_EXIT );
+}
+@endcode
+
+
+With the aid of boost::bind<>() you can even use methods or functions which
+don't quite have the correct signature:
+
+@code
+void MyHandler::OnExit( int exitCode, wxCommandEvent &, wxString goodByeMessage )
+{
+ // Do something useful
+}
+
+MyHandler myHandler;
+
+MyFrame::MyFrame()
+{
+ function< void ( wxCommandEvent & ) > exitHandler(
+ bind( &MyHandler::OnExit, &myHandler, EXIT_FAILURE, _1, "Bye" ));
+
+ Bind( wxEVT_COMMAND_MENU_SELECTED, exitHandler, wxID_EXIT );
+}
+@endcode
+
+
+To summarize, using Bind<>() requires slightly more typing but is much more
+flexible than using static event tables so don't hesitate to use it when you
+need this extra power. On the other hand, event tables are still perfectly fine
+in simple situations where this extra flexibility is not needed.
+
+
+@section overview_events_processing How Events are Processed
+
+The previous sections explain how to define event handlers but don't address
+the question of how exactly wxWidgets finds the handler to call for the
+given event. This section describes the algorithm used in detail.
+
+When an event is received from the windowing system, wxWidgets calls
+wxEvtHandler::ProcessEvent() on the first event handler object belonging to the
+window generating the event. The normal order of event table searching by
+ProcessEvent() is as follows, with the event processing stopping as soon as a
+handler is found (unless the handler calls wxEvent::Skip() in which case it
+doesn't count as having handled the event and the search continues):
+<ol>
+ <li value="0">
+ Before anything else happens, wxApp::FilterEvent() is called. If it returns
+ anything but -1 (default), the event handling stops immediately.
+ </li>
+
+ <li value="1">
+ If this event handler is disabled via a call to
+ wxEvtHandler::SetEvtHandlerEnabled() the next three steps are skipped and
+ the event handler resumes at step (5).
+ </li>
+
+ <li value="2">
+ If the object is a wxWindow and has an associated validator, wxValidator
+ gets a chance to process the event.
+ </li>
+
+ <li value="3">
+ The list of dynamically bind event handlers, i.e., those for which
+ Bind<>() was called, is consulted. Notice that this is done before
+ checking the static event table entries, so if both a dynamic and a static
+ event handler match the same event, the static one is never going to be
+ used.
+ </li>
+
+ <li value="4">
+ The event table containing all the handlers defined using the event table
+ macros in this class and its base classes is examined. Notice that this
+ means that any event handler defined in a base class will be executed at
+ this step.
+ </li>
+
+ <li value="5">
+ The event is passed to the next event handler, if any, in the event handler
+ chain, i.e., the steps (1) to (4) are done for it. This chain can be formed
+ using wxEvtHandler::SetNextHandler():
+ @image html overview_events_chain.png
+ (referring to the image, if @c A->ProcessEvent is called and it doesn't handle
+ the event, @c B->ProcessEvent will be called and so on...).
+ In the case of wxWindow you can build a stack (implemented using wxEvtHandler
+ double-linked list) using wxWindow::PushEventHandler():
+ @image html overview_events_winstack.png
+ (referring to the image, if @c W->ProcessEvent is called, it immediately calls
+ @c A->ProcessEvent; if nor @c A nor @c B handle the event, then the wxWindow
+ itself is used - i.e. the dynamically bind event handlers and static
+ event table entries of wxWindow are looked as the last possibility, after
+ all pushed event handlers were tested).
+ Note however that usually there are no wxEvtHandler chains nor wxWindows stacks
+ so this step will usually do anything.
+ </li>
+
+ <li value="6">
+ If the object is a wxWindow and the event is set to propagate (by default
+ only wxCommandEvent-derived events are set to propagate), then the
+ processing restarts from the step (1) (and excluding the step (7)) for the
+ parent window. If this object is not a window but the next handler exists,
+ the event is passed to its parent if it is a window. This ensures that in a
+ common case of (possibly several) non-window event handlers pushed on top
+ of a window, the event eventually reaches the window parent.
+ </li>
+
+ <li value="7">
+ Finally, i.e., if the event is still not processed, the wxApp object itself
+ (which derives from wxEvtHandler) gets a last chance to process it.
+ </li>
+</ol>
+
+<em>Please pay close attention to step 6!</em> People often overlook or get
+confused by this powerful feature of the wxWidgets event processing system. The
+details of event propagation up the window hierarchy are described in the
+next section.
+
+Also please notice that there are additional steps in the event handling for
+the windows-making part of wxWidgets document-view framework, i.e.,
+wxDocParentFrame, wxDocChildFrame and their MDI equivalents wxDocMDIParentFrame
+and wxDocMDIChildFrame. The parent frame classes modify step (2) above to
+send the events received by them to wxDocManager object first. This object, in
+turn, sends the event to the current view and the view itself lets its
+associated document process the event first. The child frame classes send
+the event directly to the associated view which still forwards it to its
+document object. Notice that to avoid remembering the exact order in which the
+events are processed in the document-view frame, the simplest, and recommended,
+solution is to only handle the events at the view classes level, and not in the
+document or document manager classes
+
+
+@subsection overview_events_propagation How Events Propagate Upwards
+
+As mentioned above, the events of the classes deriving from wxCommandEvent are
+propagated by default to the parent window if they are not processed in this
+window itself. But although by default only the command events are propagated
+like this, other events can be propagated as well because the event handling
+code uses wxEvent::ShouldPropagate() to check whether an event should be
+propagated. It is also possible to propagate the event only a limited number of
+times and not until it is processed (or a top level parent window is reached).
+
+Finally, there is another additional complication (which, in fact, simplifies
+life of wxWidgets programmers significantly): when propagating the command
+events up to the parent window, the event propagation stops when it
+reaches the parent dialog, if any. This means that you don't risk getting
+unexpected events from the dialog controls (which might be left unprocessed by
+the dialog itself because it doesn't care about them) when a modal dialog is
+popped up. The events do propagate beyond the frames, however. The rationale
+for this choice is that there are only a few frames in a typical application
+and their parent-child relation are well understood by the programmer while it
+may be difficult, if not impossible, to track down all the dialogs that
+may be popped up in a complex program (remember that some are created
+automatically by wxWidgets). If you need to specify a different behaviour for
+some reason, you can use wxWindow::SetExtraStyle(wxWS_EX_BLOCK_EVENTS)
+explicitly to prevent the events from being propagated beyond the given window
+or unset this flag for the dialogs that have it on by default.
+
+Typically events that deal with a window as a window (size, motion,
+paint, mouse, keyboard, etc.) are sent only to the window. Events
+that have a higher level of meaning or are generated by the window
+itself (button click, menu select, tree expand, etc.) are command
+events and are sent up to the parent to see if it is interested in the event.
+More precisely, as said above, all event classes @b not deriving from wxCommandEvent
+(see the wxEvent inheritance map) do @b not propagate upward.
+
+In some cases, it might be desired by the programmer to get a certain number
+of system events in a parent window, for example all key events sent to, but not
+used by, the native controls in a dialog. In this case, a special event handler
+will have to be written that will override ProcessEvent() in order to pass
+all events (or any selection of them) to the parent window.
+
+
+@section overview_events_custom Custom Event Summary
+
+@subsection overview_events_custom_general General approach
+
+As each event is uniquely defined by its event type, defining a custom event
+starts with defining a new event type for it. This is done using
+wxDEFINE_EVENT() macro. As an event type is a variable, it can also be
+declared using wxDECLARE_EVENT() if necessary.
+
+The next thing to do is to decide whether you need to define a custom event
+class for events of this type or if you can reuse an existing class, typically
+either wxEvent (which doesn't provide any extra information) or wxCommandEvent
+(which contains several extra fields and also propagates upwards by default).
+Both strategies are described in details below. See also the @ref
+page_samples_event for a complete example of code defining and working with the
+custom event types.
+
+
+@subsection overview_events_custom_existing Using Existing Event Classes
+
+If you just want to use a wxCommandEvent with a new event type, use one of the
+generic event table macros listed below, without having to define a new event
+class yourself.
+
+Example:
+
+@code
+// this is typically in a header: it just declares MY_EVENT event type
+wxDECLARE_EVENT(MY_EVENT, wxCommandEvent);
+
+// this is a definition so can't be in a header
+wxDEFINE_EVENT(MY_EVENT, wxCommandEvent);
+
+// example of code handling the event with event tables
+BEGIN_EVENT_TABLE(MyFrame, wxFrame)
+ EVT_MENU (wxID_EXIT, MyFrame::OnExit)
+ ...
+ EVT_COMMAND (ID_MY_WINDOW, MY_EVENT, MyFrame::OnMyEvent)
+END_EVENT_TABLE()
+
+void MyFrame::OnMyEvent(wxCommandEvent& event)
+{
+ // do something
+ wxString text = event.GetText();
+}
+
+// example of code handling the event with Bind<>():
+MyFrame::MyFrame()
+{
+ Bind(MY_EVENT, &MyFrame::OnMyEvent, this, ID_MY_WINDOW);
+}
+
+// example of code generating the event
+void MyWindow::SendEvent()
+{
+ wxCommandEvent event(MY_EVENT, GetId());
+ event.SetEventObject(this);
+
+ // Give it some contents
+ event.SetText("Hello");
+
+ // Do send it
+ ProcessWindowEvent(event);
+}
+@endcode
+
+
+@subsection overview_events_custom_ownclass Defining Your Own Event Class
+
+Under certain circumstances, you must define your own event class e.g., for
+sending more complex data from one place to another. Apart from defining your
+event class, you also need to define your own event table macro if you want to
+use event tables for handling events of this type.
+
+Here is an example:
+
+@code
+// define a new event class
+class MyPlotEvent: public wxEvent
+{
+public:
+ MyPlotEvent(wxEventType eventType, int winid, const wxPoint& pos)
+ : wxEvent(winid, eventType),
+ m_pos(pos)
+ {
+ }
+
+ // accessors
+ wxPoint GetPoint() const { return m_pos; }
+
+ // implement the base class pure virtual
+ virtual wxEvent *Clone() const { return new MyPlotEvent(*this); }
+
+private:
+ const wxPoint m_pos;
+};
- @page overview_eventhandling Event handling overview
-
- Classes: wxEvtHandler, wxWindow, wxEvent
-
- @li @ref overview_eventhandling_introduction
- @li @ref overview_eventhandling_processing
- @li @ref overview_eventhandling_prog
- @li @ref overview_eventhandling_pluggable
- @li @ref overview_eventhandling_winid
- @li @ref overview_eventhandling_custom
-
- <!-- @li @ref overview_eventhandling_macros -->
-
-
- <hr>
+// we define a single MY_PLOT_CLICKED event type associated with the class
+// above but typically you are going to have more than one event type, e.g. you
+// could also have MY_PLOT_ZOOMED or MY_PLOT_PANNED &c -- in which case you
+// would just add more similar lines here
+wxDEFINE_EVENT(MY_PLOT_CLICKED, MyPlotEvent);
- @section overview_eventhandling_introduction Introduction
-
- 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 @b OnSize.
-
- From wxWidgets 2.0, @e event tables are used instead, with a few exceptions.
- 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.
- Here's an example of an event table.
-
- @code
- BEGIN_EVENT_TABLE(MyFrame, wxFrame)
- EVT_MENU(wxID_EXIT, MyFrame::OnExit)
- EVT_MENU(DO_TEST, MyFrame::DoTest)
- EVT_SIZE(MyFrame::OnSize)
- EVT_BUTTON(BUTTON1, MyFrame::OnButton1)
- END_EVENT_TABLE()
- @endcode
-
- The first two entries map menu commands to two different member functions. The
- EVT_SIZE macro doesn't need a window identifier, since normally you are only
- interested in the current window's size events.
-
- The EVT_BUTTON macro demonstrates that the originating event does not have to
- come from the window class implementing the event table -- if the event source
- is a button within a panel within a frame, this will still work, because event
- tables are searched up through the hierarchy of windows for the command events.
- In this case, the button's event table will be searched, then the parent
- panel's, then the frame's.
-
- As mentioned before, the member functions that handle events do not have to be
- virtual. Indeed, the member functions should not be virtual as the event
- handler ignores that the functions are virtual, i.e. overriding a virtual
- member function in a derived class will not have any effect. These member
- functions take an event argument, and the class of event differs according to
- the type of event and the class of the originating window. For size events,
- wxSizeEvent is used. For menu commands and most control commands
- (such as button presses), wxCommandEvent is used. When controls get more
- complicated, then specific event classes are used, such as wxTreeEvent for
- events from wxTreeCtrl windows.
-
- As well as the event table in the implementation file, there must also be a
- DECLARE_EVENT_TABLE macro somewhere in the class declaration. For example:
-
- @code
- class MyFrame : public wxFrame
- {
- public:
- ...
- void OnExit(wxCommandEvent& event);
- void OnSize(wxSizeEvent& event);
-
- protected:
- int m_count;
- ...
-
- DECLARE_EVENT_TABLE()
- };
- @endcode
-
- Note that this macro may occur in any section of the class (public, protected
- or private) but that it is probably better to insert it at the end, as shown,
- because this macro implicitly changes the access to protected which may be
- quite unexpected if there is anything following it.
-
- Finally, if you don't like using macros for static initialization of the event
- tables you may also use wxEvtHandler::Connect to
- connect the events to the handlers dynamically, during run-time. See the
- @ref page_utils_samples_event for an example of doing it.
-
-
-
- @section overview_eventhandling_processing How events are processed
-
- When an event is received from the windowing system, wxWidgets calls
- wxEvtHandler::ProcessEvent on the first
- event handler object belonging to the window generating the event.
-
- 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.
-
- For example it is possible to filter out a number of key events sent by the
- system to a native text control by overriding wxTextCtrl and defining a
- handler for key events using EVT_KEY_DOWN. This would indeed prevent
- any key events from being sent to the native control - which might not be
- what is desired. In this case the event handler function has to call Skip()
- so as to indicate that the search for the event handler should continue.
-
- To summarize, instead of explicitly calling the base class version as you
- would have done with C++ virtual functions (i.e. @e wxTextCtrl::OnChar()),
- you should instead call wxEvent::Skip.
-
- In practice, this would look like this if the derived text control only
- accepts 'a' to 'z' and 'A' to 'Z':
-
- @code
- void MyTextCtrl::OnChar(wxKeyEvent& event)
- {
- if ( isalpha( event.KeyCode() ) )
- {
- // key code is within legal range. we call event.Skip() so the
- // event can be processed either in the base wxWidgets class
- // or the native control.
-
- event.Skip();
- }
- else
- {
- // illegal key hit. we don't call event.Skip() so the
- // event is not processed anywhere else.
-
- wxBell();
- }
- }
- @endcode
-
- The normal order of event table searching by ProcessEvent is as follows:
-
- @li If the object is disabled (via a call to wxEvtHandler::SetEvtHandlerEnabled)
- the function skips to step (6).
- @li If the object is a wxWindow, @b ProcessEvent is recursively called on the window's
- wxValidator. If this returns @true, the function exits.
- @li @b SearchEventTable is called for this event handler. If this fails, the base
- class table is tried, and so on until no more tables exist or an appropriate
- function was found, in which case the function exits.
- @li The search is applied down the entire chain of event handlers (usually the chain has
- a length of one). If this succeeds, the function exits.
- @li If the object is a wxWindow and the event is set to set to propagate (in the library only
- wxCommandEvent based events are set to propagate), @b ProcessEvent is recursively applied
- to the parent window's event handler. If this returns @true, the function exits.
- @li Finally, @b ProcessEvent is called on the wxApp object.
-
- <b>Pay close attention to Step 5</b>. People often overlook or get
- confused by this powerful feature of the wxWidgets event processing
- system. To put it a different way, events set to propagate
- (see wxEvent::ShouldPropagate)
- (most likely derived either directly or indirectly from wxCommandEvent)
- will travel up the containment hierarchy from child to parent until the
- maximal propagation level is reached or an event handler is found that
- doesn't call @c event.Skip().
-
- Finally, there is another additional complication (which, in fact, simplifies
- 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
- the dialog itself because it doesn't care about them) when a modal dialog is
- popped up. The events do propagate beyond the frames, however. The rationale
- for this choice is that there are only a few frames in a typical application
- 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 wxWidgets). If you need to specify a different behaviour for
- some reason, you can use wxWindow::SetExtraStyle(wxWS_EX_BLOCK_EVENTS)
- explicitly to prevent the events from being propagated beyond the given window
- or unset this flag for the dialogs which have it on by default.
-
- Typically events that deal with a window as a window (size, motion,
- paint, mouse, keyboard, etc.) are sent only to the window. Events
- that have a higher level of meaning and/or are generated by the window
- itself, (button click, menu select, tree expand, etc.) are command
- events and are sent up to the parent to see if it is interested in the event.
-
- Note that your application may wish to override ProcessEvent to redirect processing of
- events. This is done in the document/view framework, for example, to allow event handlers
- to be defined in the document or view. To test for command events (which will probably
- be the only events you wish to redirect), you may use wxEvent::IsCommandEvent for efficiency,
- 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 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:
-
- @li wxEvent: The event base class
- @li wxActivateEvent: A window or application activation event
- @li wxCloseEvent: A close window or end session event
- @li wxEraseEvent: An erase background event
- @li wxFocusEvent: A window focus event
- @li wxKeyEvent: A keypress event
- @li wxIdleEvent: An idle event
- @li wxInitDialogEvent: A dialog initialisation event
- @li wxJoystickEvent: A joystick event
- @li wxMenuEvent: A menu event
- @li wxMouseEvent: A mouse event
- @li wxMoveEvent: A move event
- @li wxPaintEvent: A paint event
- @li wxQueryLayoutInfoEvent: Used to query layout information
- @li wxSetCursorEvent: Used for special cursor processing based on current mouse position
- @li wxSizeEvent: A size event
- @li wxScrollWinEvent: A scroll event sent by a scrolled window (not a scroll bar)
- @li wxSysColourChangedEvent: A system colour change event
-
- In some cases, it might be desired by the programmer to get a certain number
- of system events in a parent window, for example all key events sent to, but not
- used by, the native controls in a dialog. In this case, a special event handler
- will have to be written that will override ProcessEvent() in order to pass
- all events (or any selection of them) to the parent window.
-
-
- @section overview_eventhandling_prog Events generated by the user vs programmatically generated events
-
- While generically wxEvents can be generated both by user
- actions (e.g. resize of a wxWindow) and by calls to functions
- (e.g. wxWindow::SetSize), wxWidgets controls normally send wxCommandEvent-derived
- events only for the user-generated events. The only @b exceptions to this rule are:
-
- @li wxNotebook::AddPage: No event-free alternatives
- @li wxNotebook::AdvanceSelection: No event-free alternatives
- @li wxNotebook::DeletePage: No event-free alternatives
- @li wxNotebook::SetSelection: Use wxNotebook::ChangeSelection instead, as
- wxNotebook::SetSelection is deprecated
- @li wxTreeCtrl::Delete: No event-free alternatives
- @li wxTreeCtrl::DeleteAllItems: No event-free alternatives
- @li wxTreeCtrl::EditLabel: No event-free alternatives
- @li All wxTextCtrl methods
-
- wxTextCtrl::ChangeValue can be used instead of wxTextCtrl::SetValue but the other
- functions, such as wxTextCtrl::Replace or wxTextCtrl::WriteText don't have event-free
- equivalents.
-
-
-
- @section overview_eventhandling_pluggable Pluggable event handlers
-
- 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,
- defining the appropriate event table, and then call wxWindow::SetEventHandler
- (or, preferably, wxWindow::PushEventHandler) to make this
- event handler the object that responds to events. This way, you can avoid
- 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.
-
- One use of PushEventHandler is to temporarily or permanently change the
- behaviour of the GUI. For example, you might want to invoke a dialog editor
- in your application that changes aspects of dialog boxes. You can
- grab all the input for an existing dialog box, and edit it 'in situ',
- before restoring its behaviour to normal. So even if the application
- has derived new classes to customize behaviour, your utility can indulge
- in a spot of body-snatching. It could be a useful technique for on-line
- tutorials, too, where you take a user through a serious of steps and
- don't want them to diverge from the lesson. Here, you can examine the events
- coming from buttons and windows, and if acceptable, pass them through to
- the original event handler. Use PushEventHandler/PopEventHandler
- to form a chain of event handlers, where each handler processes a different
- range of events independently from the other handlers.
-
-
-
- @section overview_eventhandling_winid Window identifiers
-
- Window identifiers are integers, and are used to
- uniquely determine window identity in the event system (though you can use it
- for other purposes). In fact, identifiers do not need to be unique
- across your entire application just so long as they are unique within a
- particular context you're interested in, such as a frame and its children. You
- may use the @c wxID_OK identifier, for example, on any number of dialogs so
- long as you don't have several within the same dialog.
-
- If you pass @c wxID_ANY to a window constructor, an identifier will be
- 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 @c wxID_ANY
- in the event table or wxEvtHandler::Connect call
- as well. The automatically generated identifiers are always negative and so
- will never conflict with the user-specified identifiers which must be always
- positive.
-
- The following standard identifiers are supplied. You can use wxID_HIGHEST to
- determine the number above which it is safe to define your own identifiers. Or,
- you can use identifiers below wxID_LOWEST.
+// if you want to support old compilers you need to use some ugly macros:
+typedef void (wxEvtHandler::*MyPlotEventFunction)(MyPlotEvent&);
+#define MyPlotEventHandler(func) wxEVENT_HANDLER_CAST(MyPlotEventFunction, func)
+
+// if your code is only built using reasonably modern compilers, you could just
+// do this instead:
+#define MyPlotEventHandler(func) (&func)
+
+// finally define a macro for creating the event table entries for the new
+// event type
+//
+// remember that you don't need this at all if you only use Bind<>() and that
+// you can replace MyPlotEventHandler(func) with just &func unless you use a
+// really old compiler
+#define MY_EVT_PLOT_CLICK(id, func) \
+ wx__DECLARE_EVT1(MY_PLOT_CLICKED, id, MyPlotEventHandler(func))
+
+
+// example of code handling the event (you will use one of these methods, not
+// both, of course):
+BEGIN_EVENT_TABLE(MyFrame, wxFrame)
+ EVT_PLOT(ID_MY_WINDOW, MyFrame::OnPlot)
+END_EVENT_TABLE()
+
+MyFrame::MyFrame()
+{
+ Bind(MY_PLOT_CLICKED, &MyFrame::OnPlot, this, ID_MY_WINDOW);
+}
+
+void MyFrame::OnPlot(MyPlotEvent& event)
+{
+ ... do something with event.GetPoint() ...
+}
+
+
+// example of code generating the event:
+void MyWindow::SendEvent()
+{
+ MyPlotEvent event(MY_PLOT_CLICKED, GetId(), wxPoint(...));
+ event.SetEventObject(this);
+ ProcessWindowEvent(event);
+}
+@endcode
+
+
+
+@section overview_events_misc Miscellaneous Notes
+
+@subsection overview_events_virtual Event Handlers vs Virtual Methods
+
+It may be noted that wxWidgets' event processing system implements something
+close to virtual methods in normal C++ in spirit: both of these mechanisms
+allow you to alter the behaviour of the base class by defining the event handling
+functions in the derived classes.
+
+There is however an important difference between the two mechanisms when you
+want to invoke the default behaviour, as implemented by the base class, from a
+derived class handler. With the virtual functions, you need to call the base
+class function directly and you can do it either in the beginning of the
+derived class handler function (to post-process the event) or at its end (to
+pre-process the event). With the event handlers, you only have the option of
+pre-processing the events and in order to still let the default behaviour
+happen you must call wxEvent::Skip() and @em not call the base class event
+handler directly. In fact, the event handler probably doesn't even exist in the
+base class as the default behaviour is often implemented in platform-specific
+code by the underlying toolkit or OS itself. But even if it does exist at
+wxWidgets level, it should never be called directly as the event handlers are
+not part of wxWidgets API and should never be called directly.
+
+
+
+@subsection overview_events_prog User Generated Events vs Programmatically Generated Events
+
+While generically wxEvents can be generated both by user
+actions (e.g., resize of a wxWindow) and by calls to functions
+(e.g., wxWindow::SetSize), wxWidgets controls normally send wxCommandEvent-derived
+events only for the user-generated events. The only @b exceptions to this rule are:
+
+@li wxNotebook::AddPage: No event-free alternatives
+@li wxNotebook::AdvanceSelection: No event-free alternatives
+@li wxNotebook::DeletePage: No event-free alternatives
+@li wxNotebook::SetSelection: Use wxNotebook::ChangeSelection instead, as
+ wxNotebook::SetSelection is deprecated
+@li wxTreeCtrl::Delete: No event-free alternatives
+@li wxTreeCtrl::DeleteAllItems: No event-free alternatives
+@li wxTreeCtrl::EditLabel: No event-free alternatives
+@li All wxTextCtrl methods
+
+wxTextCtrl::ChangeValue can be used instead of wxTextCtrl::SetValue but the other
+functions, such as wxTextCtrl::Replace or wxTextCtrl::WriteText don't have event-free
+equivalents.
+
+
+
+@subsection overview_events_pluggable Pluggable Event Handlers
+
+<em>TODO: Probably deprecated, Bind() provides a better way to do this</em>
+
+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,
+defining the appropriate event table, and then call wxWindow::SetEventHandler
+(or, preferably, wxWindow::PushEventHandler) to make this
+event handler the object that responds to events. This way, you can avoid
+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.
+
+One use of PushEventHandler is to temporarily or permanently change the
+behaviour of the GUI. For example, you might want to invoke a dialog editor
+in your application that changes aspects of dialog boxes. You can
+grab all the input for an existing dialog box, and edit it 'in situ',
+before restoring its behaviour to normal. So even if the application
+has derived new classes to customize behaviour, your utility can indulge
+in a spot of body-snatching. It could be a useful technique for on-line
+tutorials, too, where you take a user through a serious of steps and
+don't want them to diverge from the lesson. Here, you can examine the events
+coming from buttons and windows, and if acceptable, pass them through to
+the original event handler. Use PushEventHandler/PopEventHandler
+to form a chain of event handlers, where each handler processes a different
+range of events independently from the other handlers.
+
+
+
+@subsection overview_events_winid Window Identifiers
+
+Window identifiers are integers, and are used to
+uniquely determine window identity in the event system (though you can use it
+for other purposes). In fact, identifiers do not need to be unique
+across your entire application as long they are unique within the
+particular context you're interested in, such as a frame and its children. You
+may use the @c wxID_OK identifier, for example, on any number of dialogs
+as long as you don't have several within the same dialog.
+
+If you pass @c wxID_ANY to a window constructor, an identifier will be
+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 or because you process the events
+from all controls in one place (in which case you should specify @c wxID_ANY
+in the event table or wxEvtHandler::Bind call
+as well). The automatically generated identifiers are always negative and so
+will never conflict with the user-specified identifiers which must be always
+positive.
+
+See @ref page_stdevtid for the list of standard identifiers available.
+You can use wxID_HIGHEST to determine the number above which it is safe to
+define your own identifiers. Or, you can use identifiers below wxID_LOWEST.
+Finally, you can allocate identifiers dynamically using wxNewId() function too.
+If you use wxNewId() consistently in your application, you can be sure that
+your identifiers don't conflict accidentally.
+
+
+@subsection overview_events_custom_generic Generic Event Table Macros
+
+@beginTable
+@row2col{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.}
+@row2col{EVT_CUSTOM_RANGE(event\, id1\, id2\, func),
+ The same as EVT_CUSTOM, but responds to a range of window identifiers.}
+@row2col{EVT_COMMAND(id\, event\, func),
+ The same as EVT_CUSTOM, but expects a member function with a
+ wxCommandEvent argument.}
+@row2col{EVT_COMMAND_RANGE(id1\, id2\, event\, func),
+ The same as EVT_CUSTOM_RANGE, but
+ expects a member function with a wxCommandEvent argument.}
+@row2col{EVT_NOTIFY(event\, id\, func),
+ The same as EVT_CUSTOM, but
+ expects a member function with a wxNotifyEvent argument.}
+@row2col{EVT_NOTIFY_RANGE(event\, id1\, id2\, func),
+ The same as EVT_CUSTOM_RANGE, but
+ expects a member function with a wxNotifyEvent argument.}
+@endTable
+
+
+
+@subsection overview_events_list List of wxWidgets events
+
+For the full list of event classes, please see the
+@ref group_class_events "event classes group page".
- @code
- #define wxID_ANY -1
-
- #define wxID_LOWEST 4999
-
- #define wxID_OPEN 5000
- #define wxID_CLOSE 5001
- #define wxID_NEW 5002
- #define wxID_SAVE 5003
- #define wxID_SAVEAS 5004
- #define wxID_REVERT 5005
- #define wxID_EXIT 5006
- #define wxID_UNDO 5007
- #define wxID_REDO 5008
- #define wxID_HELP 5009
- #define wxID_PRINT 5010
- #define wxID_PRINT_SETUP 5011
- #define wxID_PREVIEW 5012
- #define wxID_ABOUT 5013
- #define wxID_HELP_CONTENTS 5014
- #define wxID_HELP_COMMANDS 5015
- #define wxID_HELP_PROCEDURES 5016
- #define wxID_HELP_CONTEXT 5017
-
- #define wxID_CUT 5030
- #define wxID_COPY 5031
- #define wxID_PASTE 5032
- #define wxID_CLEAR 5033
- #define wxID_FIND 5034
- #define wxID_DUPLICATE 5035
- #define wxID_SELECTALL 5036
- #define wxID_DELETE 5037
- #define wxID_REPLACE 5038
- #define wxID_REPLACE_ALL 5039
- #define wxID_PROPERTIES 5040
-
- #define wxID_VIEW_DETAILS 5041
- #define wxID_VIEW_LARGEICONS 5042
- #define wxID_VIEW_SMALLICONS 5043
- #define wxID_VIEW_LIST 5044
- #define wxID_VIEW_SORTDATE 5045
- #define wxID_VIEW_SORTNAME 5046
- #define wxID_VIEW_SORTSIZE 5047
- #define wxID_VIEW_SORTTYPE 5048
-
- #define wxID_FILE1 5050
- #define wxID_FILE2 5051
- #define wxID_FILE3 5052
- #define wxID_FILE4 5053
- #define wxID_FILE5 5054
- #define wxID_FILE6 5055
- #define wxID_FILE7 5056
- #define wxID_FILE8 5057
- #define wxID_FILE9 5058
-
- #define wxID_OK 5100
- #define wxID_CANCEL 5101
- #define wxID_APPLY 5102
- #define wxID_YES 5103
- #define wxID_NO 5104
- #define wxID_STATIC 5105
-
- #define wxID_HIGHEST 5999
- @endcode
-
-
-
- <!--
-
- NOTE: this list is incomplete and it's a trouble to maintain it!
- we must find an automatic way to generate it
-
-
- @section overview_eventhandling_macros Event macros summary
-
- @b Macros listed by event class
- The documentation for specific event macros is organised by event class. Please refer
- to these sections for details.
-
-
-
-
-
-
- #wxActivateEvent
-
-
-
-
- The EVT_ACTIVATE and EVT_ACTIVATE_APP macros intercept
- activation and deactivation events.
-
-
-
-
-
- #wxCommandEvent
-
-
-
-
- A range of commonly-used control events.
-
-
-
-
-
- #wxCloseEvent
-
-
-
-
- The EVT_CLOSE macro handles window closure
- called via wxWindow::Close.
-
-
-
-
-
- #wxDropFilesEvent
-
-
-
-
- The EVT_DROP_FILES macros handles
- file drop events.
-
-
-
-
-
- #wxEraseEvent
-
-
-
-
- The EVT_ERASE_BACKGROUND macro is used to handle window erase requests.
-
-
-
-
-
- #wxFocusEvent
-
-
-
-
- The EVT_SET_FOCUS and EVT_KILL_FOCUS macros are used to handle keyboard focus events.
-
-
-
-
-
- #wxKeyEvent
-
-
-
-
- EVT_CHAR, EVT_KEY_DOWN and
- EVT_KEY_UP macros handle keyboard input for any window.
-
-
-
-
-
- #wxIdleEvent
-
-
-
-
- The EVT_IDLE macro handle application idle events
- (to process background tasks, for example).
-
-
-
-
-
- #wxInitDialogEvent
-
-
-
-
- The EVT_INIT_DIALOG macro is used
- to handle dialog initialisation.
-
-
-
-
-
- #wxListEvent
-
-
-
-
- These macros handle #wxListCtrl events.
-
-
-
-
-
- #wxMenuEvent
-
-
-
-
- These macros handle special menu events (not menu commands).
-
-
-
-
-
- #wxMouseEvent
-
-
-
-
- Mouse event macros can handle either individual
- mouse events or all mouse events.
-
-
-
-
-
- #wxMoveEvent
-
-
-
-
- The EVT_MOVE macro is used to handle a window move.
-
-
-
-
-
- #wxPaintEvent
-
-
-
-
- The EVT_PAINT macro is used to handle window paint requests.
-
-
-
-
-
- #wxScrollEvent
-
-
-
-
- These macros are used to handle scroll events from
- #wxScrollBar, #wxSlider,and #wxSpinButton.
-
-
-
-
-
- #wxSetCursorEvent
-
-
-
-
- The EVT_SET_CURSOR macro is used for special cursor processing.
-
-
-
-
-
- #wxSizeEvent
-
-
-
-
- The EVT_SIZE macro is used to handle a window resize.
-
-
-
-
-
- #wxSplitterEvent
-
-
-
-
- The EVT_SPLITTER_SASH_POS_CHANGED, EVT_SPLITTER_UNSPLIT
- and EVT_SPLITTER_DCLICK macros are used to handle the various splitter window events.
-
-
-
-
-
- #wxSysColourChangedEvent
-
-
-
-
- The EVT_SYS_COLOUR_CHANGED macro is used to handle
- events informing the application that the user has changed the system colours (Windows only).
-
-
-
-
-
- #wxTreeEvent
-
-
-
-
- These macros handle #wxTreeCtrl events.
-
-
-
-
-
- #wxUpdateUIEvent
-
-
-
-
- The EVT_UPDATE_UI macro is used to handle user interface
- update pseudo-events, which are generated to give the application the chance to update the visual state of menus,
- toolbars and controls.
-
-
- -->
-
-
-
- @section overview_eventhandling_custom Custom event summary
-
- @subsection overview_eventhandling_custom_general General approach
-
- Since version 2.2.x of wxWidgets, each event type is identified by ID which
- is given to the event type @e 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 @b 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
- wxEvent or 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:
-
- @code
- // 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)
- @endcode
-
- You can ignore the @e 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 @ref page_utils_samples_event for an example of code
- defining and working with the custom event types.
-
-
- @subsection overview_eventhandling_custom_existing Using existing event classes
-
- If you just want to use a 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 wxEvent::Clone()
- method for posting events between threads etc. This could look like this
- in your code:
-
- @code
- 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 )
- {
- // 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 );
- }
- @endcode
-
-
- @subsection overview_eventhandling_custom_generic Generic event table macros
-
- @beginTable
- @row2col{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.}
- @row2col{EVT_CUSTOM_RANGE(event\, id1\, id2\, func),
- The same as EVT_CUSTOM, but responds to a range of window identifiers.}
- @row2col{EVT_COMMAND(id\, event\, func),
- The same as EVT_CUSTOM, but expects a member function with a
- wxCommandEvent argument.}
- @row2col{EVT_COMMAND_RANGE(id1\, id2\, event\, func),
- The same as EVT_CUSTOM_RANGE, but
- expects a member function with a wxCommandEvent argument.}
- @row2col{EVT_NOTIFY(event\, id\, func),
- The same as EVT_CUSTOM, but
- expects a member function with a wxNotifyEvent argument.}
- @row2col{EVT_NOTIFY_RANGE(event\, id1\, id2\, func),
- The same as EVT_CUSTOM_RANGE, but
- expects a member function with a wxNotifyEvent argument.}
- @endTable
-
-
- @subsection overview_eventhandling_custom_ownclass 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:
-
- @code
- // 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 );
- }
- @endcode
*/
projects / wxWidgets.git / blobdiff