1\section{\class{wxUpdateUIEvent}}\label{wxupdateuievent}
2
3This class is used for pseudo-events which are called by wxWidgets
4to give an application the chance to update various user interface elements.
5
6\wxheading{Derived from}
7
8\helpref{wxCommandEvent}{wxcommandevent}\\
9\helpref{wxEvent}{wxevent}\\
10\helpref{wxObject}{wxobject}
11
12\wxheading{Include files}
13
14<wx/event.h>
15
16\wxheading{Event table macros}
17
18To process an update event, use these event handler macros to direct input to member
19functions that take a wxUpdateUIEvent argument.
20
21\twocolwidtha{7cm}
22\begin{twocollist}\itemsep=0pt
23\twocolitem{{\bf EVT\_UPDATE\_UI(id, func)}}{Process a wxEVT\_UPDATE\_UI event for the command with the given id.}
24\twocolitem{{\bf EVT\_UPDATE\_UI\_RANGE(id1, id2, func)}}{Process a wxEVT\_UPDATE\_UI event for any command with id included in the given range.}
25\end{twocollist}
26
27\wxheading{Remarks}
28
29Without update UI events, an application has to work hard to check/uncheck, enable/disable,
30show/hide, and set the text for elements such as menu items and toolbar buttons.
31The code for doing this has to be mixed up with the code that is invoked when
32an action is invoked for a menu item or button.
33
34With update UI events, you define an event handler to look at the state of
35the application and change UI elements accordingly. wxWidgets will call your
36member functions in idle time, so you don't have to worry where to call this code.
37In addition to being a clearer and more declarative method, it also means you
38don't have to worry whether you're updating a toolbar or menubar identifier.
39The same handler can update a menu item and toolbar button, if the identifier is the same.
40
41Instead of directly manipulating the menu or button, you call functions in the event
42object, such as \helpref{wxUpdateUIEvent::Check}{wxupdateuieventcheck}. wxWidgets
43will determine whether such a call has been made, and which UI element to update.
44
45These events will work for popup menus as well as menubars. Just before a menu is popped
46up, \helpref{wxMenu::UpdateUI}{wxmenuupdateui} is called to process any UI events for
47the window that owns the menu.
48
49If you find that the overhead of UI update processing is affecting
50your application, you can do one or both of the following:
51
52\begin{enumerate}
53\item Call \helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode} with
54a value of wxUPDATE\_UI\_PROCESS\_SPECIFIED, and set the extra style
55wxWS\_EX\_PROCESS\_UPDATE\_EVENTS for every window that should receive update events.
56No other windows will receive update events.
57\item Call \helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval} with
58a millisecond value to set the delay between updates. You may need
59to call \helpref{wxWindow::UpdateWindowUI}{wxwindowupdatewindowui} at critical
60points, for example when a dialog is about to be shown, in case the user
61sees a slight delay before windows are updated.
62\end{enumerate}
63
64Note that although events are sent in idle time, defining a wxIdleEvent
65handler for a window does not affect this because the events are sent from \helpref{wxWindow::OnInternalIdle}{wxwindowoninternalidle} 
66which is {\bf always} called in idle time.
67
68wxWidgets tries to optimize update events on some platforms. On Windows
69and GTK+, events for menubar items are only sent when the menu is about
70to be shown, and not in idle time.
71
72\wxheading{See also}
73
74\helpref{Event handling overview}{eventhandlingoverview}
75
76\latexignore{\rtfignore{\wxheading{Members}}}
77
78\membersection{wxUpdateUIEvent::wxUpdateUIEvent}\label{wxupdateuieventctor}
79
80\func{}{wxUpdateUIEvent}{\param{wxWindowID }{commandId = 0}}
81
82Constructor.
83
84\membersection{wxUpdateUIEvent::CanUpdate}\label{wxupdateuieventcanupdate}
85
86\func{static bool}{CanUpdate}{\param{wxWindow*}{ window}}
87
88Returns {\tt true} if it is appropriate to update (send UI update events to)
89this window.
90
91This function looks at the mode used (see \helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}),
92the wxWS\_EX\_PROCESS\_UPDATE\_EVENTS flag in {\it window},
93the time update events were last sent in idle time, and
94the update interval, to determine whether events should be sent to
95this window now. By default this will always return {\tt true} because
96the update mode is initially wxUPDATE\_UI\_PROCESS\_ALL and
97the interval is set to 0; so update events will be sent as
98often as possible. You can reduce the frequency that events
99are sent by changing the mode and/or setting an update interval.
100
101\wxheading{See also}
102
103\helpref{wxUpdateUIEvent::ResetUpdateTime}{wxupdateuieventresetupdatetime}, 
104\helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval}, 
105\helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}
106
107\membersection{wxUpdateUIEvent::Check}\label{wxupdateuieventcheck}
108
109\func{void}{Check}{\param{bool}{ check}}
110
111Check or uncheck the UI element.
112
113\membersection{wxUpdateUIEvent::Enable}\label{wxupdateuieventenable}
114
115\func{void}{Enable}{\param{bool}{ enable}}
116
117Enable or disable the UI element.
118
119\membersection{wxUpdateUIEvent::Show}\label{wxupdateuieventshow}
120
121\func{void}{Show}{\param{bool}{ show}}
122
123Show or hide the UI element.
124
125\membersection{wxUpdateUIEvent::GetChecked}\label{wxupdateuieventgetchecked}
126
127\constfunc{bool}{GetChecked}{\void}
128
129Returns true if the UI element should be checked.
130
131\membersection{wxUpdateUIEvent::GetEnabled}\label{wxupdateuieventgetenabled}
132
133\constfunc{bool}{GetEnabled}{\void}
134
135Returns true if the UI element should be enabled.
136
137\membersection{wxUpdateUIEvent::GetShown}\label{wxupdateuieventgetshown}
138
139\constfunc{bool}{GetShown}{\void}
140
141Returns true if the UI element should be shown.
142
143\membersection{wxUpdateUIEvent::GetSetChecked}\label{wxupdateuieventgetsetchecked}
144
145\constfunc{bool}{GetSetChecked}{\void}
146
147Returns true if the application has called \helpref{wxUpdateUIEvent::Check}{wxupdateuieventcheck}. For wxWidgets internal use only.
148
149\membersection{wxUpdateUIEvent::GetSetEnabled}\label{wxupdateuieventgetsetenabled}
150
151\constfunc{bool}{GetSetEnabled}{\void}
152
153Returns true if the application has called \helpref{wxUpdateUIEvent::Enable}{wxupdateuieventenable}. For wxWidgets internal use only.
154
155\membersection{wxUpdateUIEvent::GetSetShown}\label{wxupdateuieventgetsetshown}
156
157\constfunc{bool}{GetSetShown}{\void}
158
159Returns true if the application has called \helpref{wxUpdateUIEvent::Show}{wxupdateuieventshow}. For wxWidgets internal use only.
160
161\membersection{wxUpdateUIEvent::GetSetText}\label{wxupdateuieventgetsettext}
162
163\constfunc{bool}{GetSetText}{\void}
164
165Returns true if the application has called \helpref{wxUpdateUIEvent::SetText}{wxupdateuieventsettext}. For wxWidgets internal use only.
166
167\membersection{wxUpdateUIEvent::GetText}\label{wxupdateuieventgettext}
168
169\constfunc{wxString}{GetText}{\void}
170
171Returns the text that should be set for the UI element.
172
173\membersection{wxUpdateUIEvent::GetMode}\label{wxupdateuieventgetmode}
174
175\func{static wxUpdateUIMode}{GetMode}{\void}
176
177Static function returning a value specifying how wxWidgets
178will send update events: to all windows, or only to those which specify that they
179will process the events.
180
181See \helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}.
182
183\membersection{wxUpdateUIEvent::GetUpdateInterval}\label{wxupdateuieventgetupdateinterval}
184
185\func{static long}{GetUpdateInterval}{\void}
186
187Returns the current interval between updates in milliseconds.
188-1 disables updates, 0 updates as frequently as possible.
189
190See \helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval}.
191
192\membersection{wxUpdateUIEvent::ResetUpdateTime}\label{wxupdateuieventresetupdatetime}
193
194\func{static void}{ResetUpdateTime}{\void}
195
196Used internally to reset the last-updated time to the
197current time. It is assumed that update events are
198normally sent in idle time, so this is called at the end of
199idle processing.
200
201\wxheading{See also}
202
203\helpref{wxUpdateUIEvent::CanUpdate}{wxupdateuieventcanupdate}, 
204\helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval}, 
205\helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}
206
207\membersection{wxUpdateUIEvent::SetMode}\label{wxupdateuieventsetmode}
208
209\func{static void}{SetMode}{\param{wxUpdateUIMode }{mode}}
210
211Specify how wxWidgets will send update events: to
212all windows, or only to those which specify that they
213will process the events.
214
215{\it mode} may be one of the following values.
216The default is wxUPDATE\_UI\_PROCESS\_ALL.
217
218\begin{verbatim}
219enum wxUpdateUIMode
220{
221        // Send UI update events to all windows
222    wxUPDATE_UI_PROCESS_ALL,
223
224        // Send UI update events to windows that have
225        // the wxWS_EX_PROCESS_UI_UPDATES flag specified
226    wxUPDATE_UI_PROCESS_SPECIFIED
227};
228\end{verbatim}
229
230\membersection{wxUpdateUIEvent::SetText}\label{wxupdateuieventsettext}
231
232\func{void}{SetText}{\param{const wxString\&}{ text}}
233
234Sets the text for this UI element.
235
236\membersection{wxUpdateUIEvent::SetUpdateInterval}\label{wxupdateuieventsetupdateinterval}
237
238\func{static void}{SetUpdateInterval}{\param{long }{updateInterval}}
239
240Sets the interval between updates in milliseconds.
241Set to -1 to disable updates, or to 0 to update as frequently as possible.
242The default is 0.
243
244Use this to reduce the overhead of UI update events if your application
245has a lot of windows. If you set the value to -1 or greater than 0,
246you may also need to call \helpref{wxWindow::UpdateWindowUI}{wxwindowupdatewindowui} 
247at appropriate points in your application, such as when a dialog
248is about to be shown.
249
250