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removed several out of date/wrong sentences; mention wxEvtHandler::Connect()

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@19257 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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Vadim Zeitlin 2003-02-19 18:54:07 +00:00
parent 2aefc52854
commit 2862acdeb7
1 changed files with 59 additions and 36 deletions
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95
docs/latex/wx/tevent.tex
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@ -26,48 +26,62 @@ BEGIN_EVENT_TABLE(MyFrame, wxFrame)
END_EVENT_TABLE()
\end{verbatim}
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. (In fact you could intercept a particular window's size event
by using EVT\_CUSTOM(wxEVT\_SIZE, id, func).)
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. In this
case, the button's event table will be searched, then the parent panel's, then the frame's.
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, \helpref{wxSizeEvent}{wxsizeevent} is used. For menu commands and most control
commands (such as button presses), \helpref{wxCommandEvent}{wxcommandevent} is used.
When controls get more complicated, then specific event classes are used, such
as \helpref{wxTreeEvent}{wxtreeevent} for events from \helpref{wxTreeCtrl}{wxtreectrl} windows.
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,
\helpref{wxSizeEvent}{wxsizeevent} is used. For menu commands and most
control commands (such as button presses),
\helpref{wxCommandEvent}{wxcommandevent} is used. When controls get more
complicated, then specific event classes are used, such as
\helpref{wxTreeEvent}{wxtreeevent} for events from
\helpref{wxTreeCtrl}{wxtreectrl} windows.
As well as the event table in the implementation file, there must be a DECLARE\_EVENT\_TABLE
macro in the class definition. For example:
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:
{\small%
\begin{verbatim}
class MyFrame: public wxFrame {
DECLARE_DYNAMIC_CLASS(MyFrame)
class MyFrame : public wxFrame
{
public:
...
void OnExit(wxCommandEvent& event);
void OnSize(wxSizeEvent& event);
protected:
int m_count;
...
DECLARE_EVENT_TABLE()
};
\end{verbatim}
}%
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 \helpref{wxEvtHandler::Connect}{wxevthandlerconnect} to
connect the events to the handlers dynamically, during run-time. See the
\helpref{event sample}{sampleevent} for an example of doing it.
\subsection{How events are processed}\label{eventprocessing}
When an event is received from the windowing system, wxWindows calls
@ -249,22 +263,31 @@ range of events independently from the other handlers.
\subsection{Window identifiers}\label{windowids}
\index{identifiers}\index{wxID}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 wxID\_OK identifier, for example, on
any number of dialogs so long as you don't have several within the same dialog.
\index{identifiers}\index{wxID}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 {\tt 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 -1 to a window constructor, an identifier will be generated for you, but beware:
if things don't respond in the way they should, it could be because of an id conflict. It is safer
to supply window ids at all times. Automatic generation of identifiers starts at 1 so may well conflict
with your own identifiers.
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
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}
in the event table or \helpref{wxEvtHandler::Connect}{wxevthandlerconnect} 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.
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.
\begin{verbatim}
#define wxID_ANY -1
#define wxID_LOWEST 4999
#define wxID_OPEN 5000