15d83f726c
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@29255 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
269 lines
9.6 KiB
TeX
269 lines
9.6 KiB
TeX
\section{\class{wxUpdateUIEvent}}\label{wxupdateuievent}
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This class is used for pseudo-events which are called by wxWidgets
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to give an application the chance to update various user interface elements.
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\wxheading{Derived from}
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\helpref{wxCommandEvent}{wxcommandevent}\\
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\helpref{wxEvent}{wxevent}\\
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\helpref{wxObject}{wxobject}
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\wxheading{Include files}
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<wx/event.h>
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\wxheading{Event table macros}
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To process an update event, use these event handler macros to direct input to member
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functions that take a wxUpdateUIEvent argument.
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\twocolwidtha{7cm}
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\begin{twocollist}\itemsep=0pt
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\twocolitem{{\bf EVT\_UPDATE\_UI(id, func)}}{Process a wxEVT\_UPDATE\_UI event for the command with the given id.}
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\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.}
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\end{twocollist}
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\wxheading{Remarks}
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Without update UI events, an application has to work hard to check/uncheck, enable/disable,
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and set the text for elements such as menu items and toolbar buttons.
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The code for doing this has to be mixed up with the code that is invoked when
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an action is invoked for a menu item or button.
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With update UI events, you define an event handler to look at the state of
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the application and change UI elements accordingly. wxWidgets will call your
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member functions in idle time, so you don't have to worry where to call this code.
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In addition to being a clearer and more declarative method, it also means you
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don't have to worry whether you're updating a toolbar or menubar identifier.
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The same handler can update a menu item and toolbar button, if the identifier is the same.
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Instead of directly manipulating the menu or button, you call functions in the event
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object, such as \helpref{wxUpdateUIEvent::Check}{wxupdateuieventcheck}. wxWidgets
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will determine whether such a call has been made, and which UI element to update.
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These events will work for popup menus as well as menubars. Just before a menu is popped
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up, \helpref{wxMenu::UpdateUI}{wxmenuupdateui} is called to process any UI events for
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the window that owns the menu.
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If you find that the overhead of UI update processing is affecting
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your application, you can do one or both of the following:
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\begin{enumerate}
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\item Call \helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode} with
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a value of wxUPDATE\_UI\_PROCESS\_SPECIFIED, and set the extra style
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wxWS\_EX\_PROCESS\_UPDATE\_EVENTS for every window that should receive update events.
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No other windows will receive update events.
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\item Call \helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval} with
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a millisecond value to set the delay between updates. You may need
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to call \helpref{wxWindow::UpdateWindowUI}{wxwindowupdatewindowui} at critical
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points, for example when a dialog is about to be shown, in case the user
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sees a slight delay before windows are updated.
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\end{enumerate}
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Note that although events are sent in idle time, defining a wxIdleEvent
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handler for a window does not affect this because the events are sent from \helpref{wxWindow::OnInternalIdle}{wxwindowoninternalidle}
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which is {\bf always} called in idle time.
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wxWidgets tries to optimize update events on some platforms. On Windows
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and GTK+, events for menubar items are only sent when the menu is about
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to be shown, and not in idle time.
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\wxheading{See also}
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\helpref{Event handling overview}{eventhandlingoverview}
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxUpdateUIEvent::wxUpdateUIEvent}\label{wxupdateuieventctor}
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\func{}{wxUpdateUIEvent}{\param{wxWindowID }{commandId = 0}}
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Constructor.
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\membersection{wxUpdateUIEvent::m\_checked}\label{wxupdateuieventmchecked}
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\member{bool}{m\_checked}
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true if the element should be checked, false otherwise.
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\membersection{wxUpdateUIEvent::m\_enabled}\label{wxupdateuieventmenabled}
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\member{bool}{m\_checked}
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true if the element should be enabled, false otherwise.
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\membersection{wxUpdateUIEvent::m\_setChecked}\label{wxupdateuieventmsetchecked}
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\member{bool}{m\_setChecked}
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true if the application has set the {\bf m\_checked} member.
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\membersection{wxUpdateUIEvent::m\_setEnabled}\label{wxupdateuieventmsetenabled}
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\member{bool}{m\_setEnabled}
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true if the application has set the {\bf m\_enabled} member.
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\membersection{wxUpdateUIEvent::m\_setText}\label{wxupdateuieventmsettext}
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\member{bool}{m\_setText}
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true if the application has set the {\bf m\_text} member.
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\membersection{wxUpdateUIEvent::m\_text}\label{wxupdateuieventmtext}
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\member{wxString}{m\_text}
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Holds the text with which the the application wishes to
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update the UI element.
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\membersection{wxUpdateUIEvent::CanUpdate}\label{wxupdateuieventcanupdate}
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\func{static bool}{CanUpdate}{\param{wxWindow*}{ window}}
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Returns {\tt true} if it is appropriate to update (send UI update events to)
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this window.
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This function looks at the mode used (see \helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}),
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the wxWS\_EX\_PROCESS\_UPDATE\_EVENTS flag in {\it window},
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the time update events were last sent in idle time, and
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the update interval, to determine whether events should be sent to
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this window now. By default this will always return {\tt true} because
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the update mode is initially wxUPDATE\_UI\_PROCESS\_ALL and
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the interval is set to 0; so update events will be sent as
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often as possible. You can reduce the frequency that events
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are sent by changing the mode and/or setting an update interval.
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\wxheading{See also}
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\helpref{wxUpdateUIEvent::ResetUpdateTime}{wxupdateuieventresetupdatetime},
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\helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval},
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\helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}
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\membersection{wxUpdateUIEvent::Check}\label{wxupdateuieventcheck}
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\func{void}{Check}{\param{bool}{ check}}
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Check or uncheck the UI element.
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\membersection{wxUpdateUIEvent::Enable}\label{wxupdateuieventenable}
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\func{void}{Enable}{\param{bool}{ enable}}
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Enable or disable the UI element.
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\membersection{wxUpdateUIEvent::GetChecked}\label{wxupdateuieventgetchecked}
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\constfunc{bool}{GetChecked}{\void}
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Returns true if the UI element should be checked.
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\membersection{wxUpdateUIEvent::GetEnabled}\label{wxupdateuieventgetenabled}
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\constfunc{bool}{GetEnabled}{\void}
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Returns true if the UI element should be enabled.
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\membersection{wxUpdateUIEvent::GetSetChecked}\label{wxupdateuieventgetsetchecked}
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\constfunc{bool}{GetSetChecked}{\void}
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Returns true if the application has called {\bf SetChecked}. For wxWidgets internal use only.
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\membersection{wxUpdateUIEvent::GetSetEnabled}\label{wxupdateuieventgetsetenabled}
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\constfunc{bool}{GetSetEnabled}{\void}
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Returns true if the application has called {\bf SetEnabled}. For wxWidgets internal use only.
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\membersection{wxUpdateUIEvent::GetSetText}\label{wxupdateuieventgetsettext}
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\constfunc{bool}{GetSetText}{\void}
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Returns true if the application has called {\bf SetText}. For wxWidgets internal use only.
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\membersection{wxUpdateUIEvent::GetText}\label{wxupdateuieventgettext}
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\constfunc{wxString}{GetText}{\void}
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Returns the text that should be set for the UI element.
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\membersection{wxUpdateUIEvent::GetMode}\label{wxupdateuieventgetmode}
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\func{static wxUpdateUIMode}{GetMode}{\void}
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Static function returning a value specifying how wxWidgets
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will send update events: to all windows, or only to those which specify that they
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will process the events.
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See \helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}.
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\membersection{wxUpdateUIEvent::GetUpdateInterval}\label{wxupdateuieventgetupdateinterval}
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\func{static long}{GetUpdateInterval}{\void}
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Returns the current interval between updates in milliseconds.
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-1 disables updates, 0 updates as frequently as possible.
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See \helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval}.
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\membersection{wxUpdateUIEvent::ResetUpdateTime}\label{wxupdateuieventresetupdatetime}
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\func{static void}{ResetUpdateTime}{\void}
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Used internally to reset the last-updated time to the
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current time. It is assumed that update events are
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normally sent in idle time, so this is called at the end of
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idle processing.
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\wxheading{See also}
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\helpref{wxUpdateUIEvent::CanUpdate}{wxupdateuieventcanupdate},
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\helpref{wxUpdateUIEvent::SetUpdateInterval}{wxupdateuieventsetupdateinterval},
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\helpref{wxUpdateUIEvent::SetMode}{wxupdateuieventsetmode}
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\membersection{wxUpdateUIEvent::SetMode}\label{wxupdateuieventsetmode}
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\func{static void}{SetMode}{\param{wxIdleMode }{mode}}
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Specify how wxWidgets will send update events: to
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all windows, or only to those which specify that they
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will process the events.
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{\it mode} may be one of the following values.
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The default is wxUPDATE\_UI\_PROCESS\_ALL.
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\begin{verbatim}
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enum wxUpdateUIMode
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{
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// Send UI update events to all windows
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wxUPDATE_UI_PROCESS_ALL,
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// Send UI update events to windows that have
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// the wxWS_EX_PROCESS_UI_UPDATES flag specified
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wxUPDATE_UI_PROCESS_SPECIFIED
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};
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\end{verbatim}
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\membersection{wxUpdateUIEvent::SetText}\label{wxupdateuieventsettext}
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\func{void}{SetText}{\param{const wxString\&}{ text}}
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Sets the text for this UI element.
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\membersection{wxUpdateUIEvent::SetUpdateInterval}\label{wxupdateuieventsetupdateinterval}
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\func{static void}{SetUpdateInterval}{\param{long }{updateInterval}}
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Sets the interval between updates in milliseconds.
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Set to -1 to disable updates, or to 0 to update as frequently as possible.
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The default is 0.
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Use this to reduce the overhead of UI update events if your application
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has a lot of windows. If you set the value to -1 or greater than 0,
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you may also need to call \helpref{wxWindow::UpdateWindowUI}{wxwindowupdatewindowui}
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at appropriate points in your application, such as when a dialog
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is about to be shown.
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