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281 lines
15 KiB
281 lines
15 KiB
14 years ago
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<!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/kernel/qeventloop.cpp:41 -->
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>QEventLoop Class</title>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QEventLoop Class Reference</h1>
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<p>The QEventLoop class manages the event queue.
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<a href="#details">More...</a>
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<p><tt>#include <<a href="qeventloop-h.html">qeventloop.h</a>></tt>
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<p>Inherits <a href="qobject.html">QObject</a>.
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<p>Inherited by <a href="qmotif.html">QMotif</a>.
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<p><a href="qeventloop-members.html">List of all member functions.</a>
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<h2>Public Members</h2>
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<ul>
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<li class=fn><a href="#QEventLoop"><b>QEventLoop</b></a> ( QObject * parent = 0, const char * name = 0 )</li>
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<li class=fn><a href="#~QEventLoop"><b>~QEventLoop</b></a> ()</li>
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<li class=fn>enum <a href="#ProcessEvents-enum"><b>ProcessEvents</b></a> { AllEvents = 0x00, ExcludeUserInput = 0x01, ExcludeSocketNotifiers = 0x02, WaitForMore = 0x04 }</li>
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<li class=fn>typedef uint <a href="#ProcessEventsFlags"><b>ProcessEventsFlags</b></a></li>
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<li class=fn>void <a href="#processEvents"><b>processEvents</b></a> ( ProcessEventsFlags flags, int maxTime )</li>
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<li class=fn>virtual bool <a href="#processEvents-2"><b>processEvents</b></a> ( ProcessEventsFlags flags )</li>
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<li class=fn>virtual bool <a href="#hasPendingEvents"><b>hasPendingEvents</b></a> () const</li>
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<li class=fn>virtual void <a href="#registerSocketNotifier"><b>registerSocketNotifier</b></a> ( QSocketNotifier * notifier )</li>
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<li class=fn>virtual void <a href="#unregisterSocketNotifier"><b>unregisterSocketNotifier</b></a> ( QSocketNotifier * notifier )</li>
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<li class=fn>void <a href="#setSocketNotifierPending"><b>setSocketNotifierPending</b></a> ( QSocketNotifier * notifier )</li>
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<li class=fn>int <a href="#activateSocketNotifiers"><b>activateSocketNotifiers</b></a> ()</li>
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<li class=fn>int <a href="#activateTimers"><b>activateTimers</b></a> ()</li>
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<li class=fn>int <a href="#timeToWait"><b>timeToWait</b></a> () const</li>
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<li class=fn>virtual int <a href="#exec"><b>exec</b></a> ()</li>
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<li class=fn>virtual void <a href="#exit"><b>exit</b></a> ( int retcode = 0 )</li>
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<li class=fn>virtual int <a href="#enterLoop"><b>enterLoop</b></a> ()</li>
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<li class=fn>virtual void <a href="#exitLoop"><b>exitLoop</b></a> ()</li>
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<li class=fn>virtual int <a href="#loopLevel"><b>loopLevel</b></a> () const</li>
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<li class=fn>virtual void <a href="#wakeUp"><b>wakeUp</b></a> ()</li>
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</ul>
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<h2>Signals</h2>
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<ul>
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<li class=fn>void <a href="#awake"><b>awake</b></a> ()</li>
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<li class=fn>void <a href="#aboutToBlock"><b>aboutToBlock</b></a> ()</li>
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</ul>
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<hr><a name="details"></a><h2>Detailed Description</h2>
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The QEventLoop class manages the event queue.
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<p>
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<p> It receives events from the window system and other sources. It
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then sends them to <a href="qapplication.html">QApplication</a> for processing and delivery.
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<p> QEventLoop allows the application programmer to have more control
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over event delivery. Programs that perform long operations can
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call either processOneEvent() or <a href="#processEvents">processEvents</a>() with various
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ProcessEvent values OR'ed together to control which events should
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be delivered.
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<p> QEventLoop also allows the integration of an external event loop
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with the Qt event loop. The <a href="motif-extension.html#Motif">Motif</a> Extension included with Qt
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includes a reimplementation of QEventLoop for merging Qt and Motif
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events together.
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<p> To use your own instance of QEventLoop or QEventLoop subclass create
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it before you create the QApplication object.
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<p>See also <a href="application.html">Main Window and Related Classes</a> and <a href="events.html">Event Classes</a>.
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<hr><h2>Member Type Documentation</h2>
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<h3 class=fn><a name="ProcessEvents-enum"></a>QEventLoop::ProcessEvents</h3>
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<p> This enum controls the types of events processed by the
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<a href="#processEvents">processEvents</a>() functions.
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<ul>
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<li><tt>QEventLoop::AllEvents</tt> - All events are processed
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<li><tt>QEventLoop::ExcludeUserInput</tt> - Do not process user input events.
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( ButtonPress, KeyPress, etc. )
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<li><tt>QEventLoop::ExcludeSocketNotifiers</tt> - Do not process socket notifier
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events.
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<li><tt>QEventLoop::WaitForMore</tt> - Wait for events if no pending events
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are available.
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</ul><p> <p>See also <a href="#processEvents">processEvents</a>().
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<h3 class=fn><a name="ProcessEventsFlags"></a>QEventLoop::ProcessEventsFlags</h3>
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A <tt>typedef</tt> to allow various ProcessEvents values to be OR'ed together.
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<p> <p>See also <a href="#ProcessEvents-enum">ProcessEvents</a>.
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<hr><h2>Member Function Documentation</h2>
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<h3 class=fn><a name="QEventLoop"></a>QEventLoop::QEventLoop ( <a href="qobject.html">QObject</a> * parent = 0, const char * name = 0 )
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</h3>
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Creates a QEventLoop object, this object becomes the global event loop object.
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There can only be one event loop object. The QEventLoop is usually constructed
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by calling <a href="qapplication.html#eventLoop">QApplication::eventLoop</a>(). To create your own event loop object create
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it before you instantiate the <a href="qapplication.html">QApplication</a> object.
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<p> The <em>parent</em> and <em>name</em> arguments are passed on to the <a href="qobject.html">QObject</a> constructor.
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<h3 class=fn><a name="~QEventLoop"></a>QEventLoop::~QEventLoop ()
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</h3>
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Destructs the QEventLoop object.
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<h3 class=fn>void <a name="aboutToBlock"></a>QEventLoop::aboutToBlock ()<tt> [signal]</tt>
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</h3>
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<p> This signal is emitted before the event loop calls a function that
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could block.
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<p> <p>See also <a href="#awake">awake</a>().
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<h3 class=fn>int <a name="activateSocketNotifiers"></a>QEventLoop::activateSocketNotifiers ()
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</h3>
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<p> Activates all pending socket notifiers and returns the number of
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socket notifiers that were activated.
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<h3 class=fn>int <a name="activateTimers"></a>QEventLoop::activateTimers ()
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</h3>
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<p> Activates all Qt timers and returns the number of timers that were
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activated.
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<p> QEventLoop subclasses that do their own timer handling need to
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call this after the time returned by <a href="#timeToWait">timeToWait</a>() has elapsed.
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<p> Note: This function is only useful on systems where <tt>select()</tt> is
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used to block the eventloop. On Windows, this function always
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returns 0. On MacOS X, this function always returns 0 when the
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GUI is enabled. On MacOS X, this function returns the documented
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value when the GUI is disabled.
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<h3 class=fn>void <a name="awake"></a>QEventLoop::awake ()<tt> [signal]</tt>
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</h3>
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<p> This signal is emitted after the event loop returns from a
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function that could block.
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<p> <p>See also <a href="#wakeUp">wakeUp</a>() and <a href="#aboutToBlock">aboutToBlock</a>().
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<h3 class=fn>int <a name="enterLoop"></a>QEventLoop::enterLoop ()<tt> [virtual]</tt>
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</h3>
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<p> This function enters the main event loop (recursively). Do not call
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it unless you really know what you are doing.
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<h3 class=fn>int <a name="exec"></a>QEventLoop::exec ()<tt> [virtual]</tt>
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</h3>
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Enters the main event loop and waits until <a href="#exit">exit</a>() is called, and
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returns the value that was set to exit().
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<p> It is necessary to call this function to start event handling. The
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main event loop receives events from the window system and
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dispatches these to the application widgets.
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<p> Generally speaking, no user interaction can take place before
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calling <a href="#exec">exec</a>(). As a special case, modal widgets like <a href="qmessagebox.html">QMessageBox</a>
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can be used before calling exec(), because modal widgets call
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exec() to start a local event loop.
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<p> To make your application perform idle processing, i.e. executing a
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special function whenever there are no pending events, use a
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<a href="qtimer.html">QTimer</a> with 0 timeout. More advanced idle processing schemes can
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be achieved using <a href="#processEvents">processEvents</a>().
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<p> <p>See also <a href="qapplication.html#quit">QApplication::quit</a>(), <a href="#exit">exit</a>(), and <a href="#processEvents">processEvents</a>().
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<h3 class=fn>void <a name="exit"></a>QEventLoop::exit ( int retcode = 0 )<tt> [virtual]</tt>
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</h3>
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<p> Tells the event loop to exit with a return code.
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<p> After this function has been called, the event loop returns from
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the call to <a href="#exec">exec</a>(). The exec() function returns <em>retcode</em>.
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<p> By convention, a <em>retcode</em> of 0 means success, and any non-zero
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value indicates an error.
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<p> Note that unlike the C library function of the same name, this
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function <em>does</em> return to the caller -- it is event processing that
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stops.
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<p> <p>See also <a href="qapplication.html#quit">QApplication::quit</a>() and <a href="#exec">exec</a>().
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<h3 class=fn>void <a name="exitLoop"></a>QEventLoop::exitLoop ()<tt> [virtual]</tt>
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</h3>
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<p> This function exits from a recursive call to the main event loop.
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Do not call it unless you really know what you are doing.
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<h3 class=fn>bool <a name="hasPendingEvents"></a>QEventLoop::hasPendingEvents () const<tt> [virtual]</tt>
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</h3>
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<p> Returns TRUE if there is an event waiting, otherwise it returns FALSE.
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<h3 class=fn>int <a name="loopLevel"></a>QEventLoop::loopLevel () const<tt> [virtual]</tt>
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</h3>
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<p> Returns the current loop level.
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<h3 class=fn>void <a name="processEvents"></a>QEventLoop::processEvents ( <a href="qeventloop.html#ProcessEventsFlags">ProcessEventsFlags</a> flags, int maxTime )
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</h3>
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Process pending events that match <em>flags</em> for a maximum of <em>maxTime</em> milliseconds, or until there are no more events to
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process, which ever is shorter.
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<p> This function is especially useful if you have a long running
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operation and want to show its progress without allowing user
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input, i.e. by using the <a href="#ProcessEvents-enum">ExcludeUserInput</a> flag.
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<p> NOTE: This function will not process events continuously; it
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returns after all available events are processed.
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<p> NOTE: Specifying the <a href="#ProcessEvents-enum">WaitForMore</a> flag makes no sense and will
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be ignored.
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<h3 class=fn>bool <a name="processEvents-2"></a>QEventLoop::processEvents ( <a href="qeventloop.html#ProcessEventsFlags">ProcessEventsFlags</a> flags )<tt> [virtual]</tt>
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</h3>
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This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
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<p> Processes pending events that match <em>flags</em> until there are no
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more events to process.
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<p> This function is especially useful if you have a long running
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operation and want to show its progress without allowing user
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input, i.e. by using the <a href="#ProcessEvents-enum">ExcludeUserInput</a> flag.
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<p> If the <a href="#ProcessEvents-enum">WaitForMore</a> flag is set in <em>flags</em>, the behavior of
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this function is as follows:
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<p> <ul>
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<p> <li> If events are available, this function returns after processing
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them.
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<p> <li> If no events are available, this function will wait until more
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are available and return after processing newly available events.
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<p> </ul>
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<p> If the <a href="#ProcessEvents-enum">WaitForMore</a> flag is <em>not</em> set in <em>flags</em>, and no
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events are available, this function will return immediately.
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<p> NOTE: This function will not process events continuously; it
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returns after all available events are processed.
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<p> This function returns TRUE if an event was processed; otherwise it
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returns FALSE.
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<p> <p>See also <a href="#ProcessEvents-enum">ProcessEvents</a> and <a href="#hasPendingEvents">hasPendingEvents</a>().
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<h3 class=fn>void <a name="registerSocketNotifier"></a>QEventLoop::registerSocketNotifier ( <a href="qsocketnotifier.html">QSocketNotifier</a> * notifier )<tt> [virtual]</tt>
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</h3>
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<p> Registers <em>notifier</em> with the event loop. Subclasses need to
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reimplement this method to tie a socket notifier into another
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event loop. Reimplementations <em>MUST</em> call the base
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implementation.
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<h3 class=fn>void <a name="setSocketNotifierPending"></a>QEventLoop::setSocketNotifierPending ( <a href="qsocketnotifier.html">QSocketNotifier</a> * notifier )
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</h3>
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<p> Marks <em>notifier</em> as pending. The socket notifier will be
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activated the next time <a href="#activateSocketNotifiers">activateSocketNotifiers</a>() is called.
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<h3 class=fn>int <a name="timeToWait"></a>QEventLoop::timeToWait () const
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</h3>
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<p> Returns the number of milliseconds that Qt needs to handle its
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timers or -1 if there are no timers running.
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<p> QEventLoop subclasses that do their own timer handling need to use
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this to make sure that Qt's timers continue to work.
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<p> Note: This function is only useful on systems where <tt>select()</tt> is
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used to block the eventloop. On Windows, this function always
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returns -1. On MacOS X, this function always returns -1 when the
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GUI is enabled. On MacOS X, this function returns the documented
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value when the GUI is disabled.
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<h3 class=fn>void <a name="unregisterSocketNotifier"></a>QEventLoop::unregisterSocketNotifier ( <a href="qsocketnotifier.html">QSocketNotifier</a> * notifier )<tt> [virtual]</tt>
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</h3>
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<p> Unregisters <em>notifier</em> from the event loop. Subclasses need to
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reimplement this method to tie a socket notifier into another
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event loop. Reimplementations <em>MUST</em> call the base
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implementation.
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<h3 class=fn>void <a name="wakeUp"></a>QEventLoop::wakeUp ()<tt> [virtual]</tt>
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</h3><p><b>Note:</b> This function is <a href="threads.html#threadsafe">thread-safe</a> when Qt is built withthread support.</p>
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<p> Wakes up the event loop.
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<p> <p>See also <a href="#awake">awake</a>().
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<!-- eof -->
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<hr><p>
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This file is part of the <a href="index.html">Qt toolkit</a>.
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Copyright © 1995-2007
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<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>Qt 3.3.8</div>
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</table></div></address></body>
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</html>
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