wxEvtHandler

A class that can handle events from the windowing system. wxWindow (and therefore all window classes) are derived from this class.

When events are received, wxEvtHandler invokes the method listed in the event table using itself as the object. When using multiple inheritance it is imperative that the wxEvtHandler(-derived) class be the first class inherited such that the "this" pointer for the overall object will be identical to the "this" pointer for the wxEvtHandler portion.

Derived from

wxObject

Include files

<wx/event.h>

See also

See Event handling overview.



wxEvtHandler::wxEvtHandler



wxEvtHandler(void)

Constructor.



wxEvtHandler::~wxEvtHandler



~wxEvtHandler(void)

Destructor. If the handler is part of a chain, the destructor will unlink itself and restore the previous and next handlers so that they point to each other.



wxEvtHandler::AddPendingEvent



void AddPendingEvent(wxEvent& event)

This function posts an event to be processed later.

Parameters

event
Event to add to process queue.

Remarks

The difference between sending an event (using the ProcessEvent method) and posting it is that in the first case the event is processed before the function returns, while in the second case, the function returns immediately and the event will be processed sometime later (usually during the next event loop iteration).

A copy of event is made by the function, so the original can be deleted as soon as function returns (it is common that the original is created on the stack). This requires that the wxEvent::Clone method be implemented by event so that it can be duplicated and stored until it gets processed.

This is also the method to call for inter-thread communication--it will post events safely between different threads which means that this method is thread-safe by using critical sections where needed. In a multi-threaded program, you often need to inform the main GUI thread about the status of other working threads and such notification should be done using this method.

This method automatically wakes up idle handling if the underlying window system is currently idle and thus would not send any idle events. (Waking up idle handling is done calling ::wxWakeUpIdle.)



wxEvtHandler::Connect



void Connect(int id, int lastId, wxEventType eventType, wxObjectEventFunction function, wxObject* userData = NULL, wxEvtHandler* eventSink = NULL)



void Connect(int id, wxEventType eventType, wxObjectEventFunction function, wxObject* userData = NULL, wxEvtHandler* eventSink = NULL)



void Connect(wxEventType eventType, wxObjectEventFunction function, wxObject* userData = NULL, wxEvtHandler* eventSink = NULL)

Connects the given function dynamically with the event handler, id and event type. This is an alternative to the use of static event tables. See the 'event' or the old 'dynamic' sample for usage.

Parameters

id
The identifier (or first of the identifier range) to be associated with the event handler function. For the version not taking this argument, it defaults to wxID_ANY.

lastId
The second part of the identifier range to be associated with the event handler function.

eventType
The event type to be associated with this event handler.

function
The event handler function. Note that this function should be explicitly converted to the correct type which can be done using a macro called wxFooHandler for the handler for any wxFooEvent.

userData
Data to be associated with the event table entry.

eventSink
Object whose member function should be called. If this is NULL, this will be used.

Example

  frame->Connect( wxID_EXIT,
    wxEVT_COMMAND_MENU_SELECTED,
    wxCommandEventHandler(MyFrame::OnQuit) );

wxPerl での注意点: In wxPerl this function takes 4 arguments: id, lastid, type, method; if method is undef, the handler is disconnected.



wxEvtHandler::Disconnect



bool Disconnect(int id = wxID_ANY, wxEventType eventType = wxEVT_NULL, wxObjectEventFunction function = NULL, wxObject* userData = NULL, wxEvtHandler* eventSink = NULL)



bool Disconnect(int id, int lastId = wxID_ANY, wxEventType eventType = wxEVT_NULL, wxObjectEventFunction function = NULL, wxObject* userData = NULL, wxEvtHandler* eventSink = NULL)

Disconnects the given function dynamically from the event handler, using the specified parameters as search criteria and returning true if a matching function has been found and removed. This method can only disconnect functions which have been added using the wxEvtHandler::Connect method. There is no way to disconnect functions connected using the (static) event tables.

Parameters

id
The identifier (or first of the identifier range) associated with the event handler function.

lastId
The second part of the identifier range associated with the event handler function.

eventType
The event type associated with this event handler.

function
The event handler function.

userData
Data associated with the event table entry.

eventSink
Object whose member function should be called.

wxPerl での注意点: In wxPerl this function takes 3 arguments: id, lastid, type.



wxEvtHandler::GetClientData



void* GetClientData(void)

Gets user-supplied client data.

Remarks

Normally, any extra data the programmer wishes to associate with the object should be made available by deriving a new class with new data members.

See also

wxEvtHandler::SetClientData



wxEvtHandler::GetClientObject

wxClientData* GetClientObject(void) const

Get a pointer to the user-supplied client data object.

See also

wxEvtHandler::SetClientObject, wxClientData



wxEvtHandler::GetEvtHandlerEnabled



bool GetEvtHandlerEnabled(void)

Returns true if the event handler is enabled, false otherwise.

See also

wxEvtHandler::SetEvtHandlerEnabled



wxEvtHandler::GetNextHandler



wxEvtHandler* GetNextHandler(void)

Gets the pointer to the next handler in the chain.

See also

wxEvtHandler::SetNextHandler, wxEvtHandler::GetPreviousHandler, wxEvtHandler::SetPreviousHandler, wxWindow::PushEventHandler, wxWindow::PopEventHandler



wxEvtHandler::GetPreviousHandler



wxEvtHandler* GetPreviousHandler(void)

Gets the pointer to the previous handler in the chain.

See also

wxEvtHandler::SetPreviousHandler, wxEvtHandler::GetNextHandler, wxEvtHandler::SetNextHandler, wxWindow::PushEventHandler, wxWindow::PopEventHandler



wxEvtHandler::ProcessEvent



virtual bool ProcessEvent(wxEvent& event)

Processes an event, searching event tables and calling zero or more suitable event handler function(s).

Parameters

event
Event to process.

Return value

true if a suitable event handler function was found and executed, and the function did not call wxEvent::Skip.

Remarks

Normally, your application would not call this function: it is called in the wxWidgets implementation to dispatch incoming user interface events to the framework (and application).

However, you might need to call it if implementing new functionality (such as a new control) where you define new event types, as opposed to allowing the user to override virtual functions.

An instance where you might actually override the ProcessEvent function is where you want to direct event processing to event handlers not normally noticed by wxWidgets. For example, in the document/view architecture, documents and views are potential event handlers. When an event reaches a frame, ProcessEvent will need to be called on the associated document and view in case event handler functions are associated with these objects. The property classes library (wxProperty) also overrides ProcessEvent for similar reasons.

The normal order of event table searching is as follows:

  1. If the object is disabled (via a call to wxEvtHandler::SetEvtHandlerEnabled) the function skips to step (6).
  2. If the object is a wxWindow, ProcessEvent is recursively called on the window's wxValidator. If this returns true, the function exits.
  3. 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.
  4. 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.
  5. If the object is a wxWindow and the event is a wxCommandEvent, ProcessEvent is recursively applied to the parent window's event handler. If this returns true, the function exits.
  6. Finally, ProcessEvent is called on the wxApp object.

See also

wxEvtHandler::SearchEventTable



wxEvtHandler::SearchEventTable



virtual bool SearchEventTable(wxEventTable& table, wxEvent& event)

Searches the event table, executing an event handler function if an appropriate one is found.

Parameters

table
Event table to be searched.

event
Event to be matched against an event table entry.

Return value

true if a suitable event handler function was found and executed, and the function did not call wxEvent::Skip.

Remarks

This function looks through the object's event table and tries to find an entry that will match the event.

An entry will match if:

  1. The event type matches, and
  2. the identifier or identifier range matches, or the event table entry's identifier is zero.

If a suitable function is called but calls wxEvent::Skip, this function will fail, and searching will continue.

See also

wxEvtHandler::ProcessEvent



wxEvtHandler::SetClientData



void SetClientData(void* data)

Sets user-supplied client data.

Parameters

data
Data to be associated with the event handler.

Remarks

Normally, any extra data the programmer wishes to associate with the object should be made available by deriving a new class with new data members. You must not call this method and SetClientObject on the same class - only one of them.

See also

wxEvtHandler::GetClientData



wxEvtHandler::SetClientObject



void SetClientObject(wxClientData* data)

Set the client data object. Any previous object will be deleted.

See also

wxEvtHandler::GetClientObject, wxClientData



wxEvtHandler::SetEvtHandlerEnabled



void SetEvtHandlerEnabled(bool enabled)

Enables or disables the event handler.

Parameters

enabled
true if the event handler is to be enabled, false if it is to be disabled.

Remarks

You can use this function to avoid having to remove the event handler from the chain, for example when implementing a dialog editor and changing from edit to test mode.

See also

wxEvtHandler::GetEvtHandlerEnabled



wxEvtHandler::SetNextHandler



void SetNextHandler(wxEvtHandler* handler)

Sets the pointer to the next handler.

Parameters

handler
Event handler to be set as the next handler.

See also

wxEvtHandler::GetNextHandler, wxEvtHandler::SetPreviousHandler, wxEvtHandler::GetPreviousHandler, wxWindow::PushEventHandler, wxWindow::PopEventHandler



wxEvtHandler::SetPreviousHandler



void SetPreviousHandler(wxEvtHandler* handler)

Sets the pointer to the previous handler.

Parameters

handler
Event handler to be set as the previous handler.

See also

wxEvtHandler::GetPreviousHandler, wxEvtHandler::SetNextHandler, wxEvtHandler::GetNextHandler, wxWindow::PushEventHandler, wxWindow::PopEventHandler

ymasuda 平成17年11月19日