X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/1f11220943f14b4bb5190db0dfd0054304f5015c..4d2976ad6b56ff1650e15f2b949c10ec92385309:/docs/latex/wx/tevent.tex diff --git a/docs/latex/wx/tevent.tex b/docs/latex/wx/tevent.tex index 2b67f2cfa3..718f2eaae1 100644 --- a/docs/latex/wx/tevent.tex +++ b/docs/latex/wx/tevent.tex @@ -82,7 +82,11 @@ 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 it did NOT handle the event at all. +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. {\it wxTextCtrl::OnChar()}), +you should instead call \helpref{Skip}{wxeventskip}. In practice, this would look like this if the derived text control only accepts 'a' to 'z' and 'A' to 'Z': @@ -96,14 +100,14 @@ void MyTextCtrl::OnChar(wxKeyEvent& event) // key code is within legal range. we call event.Skip() so the // event can be processed either in the base wxWindows class // or the native control. - - event.Skip(); + + event.Skip(); } else { // illegal key hit. we don't call event.Skip() so the // event is not processed anywhere else. - + wxBell(); } } @@ -128,9 +132,26 @@ recursively applied to the parent window's event handler. If this returns TRUE, \item Finally, {\bf ProcessEvent} is called on the wxApp object. \end{enumerate} +{\bf Pay close attention to Step 5.} People often overlook or get +confused by this powerful feature of the wxWindows event processing +system. To put it a different way, events derived either directly or +indirectly from wxCommandEvent will travel up the containment +heirarchy from child to parent until an event handler is found that +doesn't call event.Skip(). Events not derived from wxCommandEvent are +sent only to the window they occurred in and then stop. + +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 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. As this quite often causes confusion for users, here is a list of system @@ -152,6 +173,7 @@ events which will NOT get sent to the parent's event handler: \twocolitem{\helpref{wxPaintEvent}{wxpaintevent}}{A paint event} \twocolitem{\helpref{wxQueryLayoutInfoEvent}{wxquerylayoutinfoevent}}{Used to query layout information} \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} @@ -160,7 +182,21 @@ 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. See next section. +all events (or any selection of them) to the parent window. + +\subsection{Redirection of command events to the window with the focus} + +The usual upward search through the window hierarchy for command event +handlers does not always meet an application's requirements. Say you have two +wxTextCtrl windows in a frame, plus a toolbar with Cut, Copy and Paste +buttons. To avoid the need to define event handlers in the frame +and redirect them explicitly to the window with the focus, command events +are sent to the window with the focus first, for +menu and toolbar command and UI update events only. This means that +each window can handle its own commands and UI updates independently. In +fact wxTextCtrl can handle Cut, Copy, Paste, Undo and Redo commands and UI update +requests, so no extra coding is required to support them in your menus and +toolbars. \subsection{Pluggable event handlers} @@ -301,15 +337,17 @@ to handle dialog initialisation.} \twocolitem{\helpref{wxMouseEvent}{wxmouseevent}}{Mouse event macros can handle either individual mouse events or all mouse events.} \twocolitem{\helpref{wxMoveEvent}{wxmoveevent}}{The EVT\_MOVE macro is used to handle a window move.} -\twocolitem{\helpref{wxUpdateUIEvent}{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.} \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 -windows, \helpref{wxScrollBar}{wxscrollbar}, and \helpref{wxSpinButton}{wxspinbutton}.} +\helpref{wxScrollBar}{wxscrollbar}, \helpref{wxSlider}{wxslider},and \helpref{wxSpinButton}{wxspinbutton}.} \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\_DOUBLECLICKED macros are used to handle the various splitter window events.} \twocolitem{\helpref{wxSysColourChangedEvent}{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).} \twocolitem{\helpref{wxTreeEvent}{wxtreeevent}}{These macros handle \helpref{wxTreeCtrl}{wxtreectrl} events.} +\twocolitem{\helpref{wxUpdateUIEvent}{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.} \end{twocollist}