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<h1 class="title">QEventLoop Class Reference</h1>
<!-- $$$QEventLoop-brief -->
<p>The QEventLoop class provides a means of entering and leaving an event loop. <a href="#details">More...</a></p>
<!-- @@@QEventLoop -->
<pre class="cpp"> <span class="preprocessor">#include &lt;QEventLoop&gt;</span></pre><p><b>Inherits: </b><a href="qobject.html">QObject</a>.</p>
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<tr><td class="memItemLeft rightAlign topAlign"> enum </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#ProcessEventsFlag-enum">ProcessEventsFlag</a></b> { AllEvents, ExcludeUserInputEvents, ExcludeSocketNotifiers, WaitForMoreEvents, DeferredDeletion }</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> flags </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#ProcessEventsFlag-enum">ProcessEventsFlags</a></b></td></tr>
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<h2>Public Functions</h2>
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<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#QEventLoop">QEventLoop</a></b> ( QObject * <i>parent</i> = 0 )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#dtor.QEventLoop">~QEventLoop</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> int </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#exec">exec</a></b> ( ProcessEventsFlags <i>flags</i> = AllEvents )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#exit">exit</a></b> ( int <i>returnCode</i> = 0 )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#isRunning">isRunning</a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#processEvents">processEvents</a></b> ( ProcessEventsFlags <i>flags</i> = AllEvents )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#processEvents-2">processEvents</a></b> ( ProcessEventsFlags <i>flags</i>, int <i>maxTime</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qeventloop.html#wakeUp">wakeUp</a></b> ()</td></tr>
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<!-- $$$QEventLoop-description -->
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<h2>Detailed Description</h2>
<p>The QEventLoop class provides a means of entering and leaving an event loop.</p>
<p>At any time, you can create a QEventLoop object and call <a href="qeventloop.html#exec">exec</a>() on it to start a local event loop. From within the event loop, calling <a href="qeventloop.html#exit">exit</a>() will force <a href="qeventloop.html#exec">exec</a>() to return.</p>
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<p><b>See also </b><a href="qabstracteventdispatcher.html">QAbstractEventDispatcher</a>.</p>
<!-- @@@QEventLoop -->
<div class="types">
<h2>Member Type Documentation</h2>
<!-- $$$ProcessEventsFlag$$$AllEvents$$$ExcludeUserInputEvents$$$ExcludeSocketNotifiers$$$WaitForMoreEvents$$$ExcludeUserInput$$$WaitForMore$$$X11ExcludeTimers$$$DeferredDeletion$$$EventLoopExec$$$DialogExec -->
<h3 class="flags"><a name="ProcessEventsFlag-enum"></a>enum QEventLoop::<span class="name">ProcessEventsFlag</span><br/>flags QEventLoop::<span class="name">ProcessEventsFlags</span></h3>
<p>This enum controls the types of events processed by the <a href="qeventloop.html#processEvents">processEvents</a>() functions.</p>
<table class="valuelist"><tr valign="top" class="odd"><th class="tblConst">Constant</th><th class="tblval">Value</th><th class="tbldscr">Description</th></tr>
<tr><td class="topAlign"><tt>QEventLoop::AllEvents</tt></td><td class="topAlign"><tt>0x00</tt></td><td class="topAlign">All events. Note that <a href="qevent.html#Type-enum">DeferredDelete</a> events are processed specially. See <a href="qobject.html#deleteLater">QObject::deleteLater</a>() for more details.</td></tr>
<tr><td class="topAlign"><tt>QEventLoop::ExcludeUserInputEvents</tt></td><td class="topAlign"><tt>0x01</tt></td><td class="topAlign">Do not process user input events, such as ButtonPress and KeyPress. Note that the events are not discarded; they will be delivered the next time <a href="qeventloop.html#processEvents">processEvents</a>() is called without the ExcludeUserInputEvents flag.</td></tr>
<tr><td class="topAlign"><tt>QEventLoop::ExcludeSocketNotifiers</tt></td><td class="topAlign"><tt>0x02</tt></td><td class="topAlign">Do not process socket notifier events. Note that the events are not discarded; they will be delivered the next time <a href="qeventloop.html#processEvents">processEvents</a>() is called without the ExcludeSocketNotifiers flag.</td></tr>
<tr><td class="topAlign"><tt>QEventLoop::WaitForMoreEvents</tt></td><td class="topAlign"><tt>0x04</tt></td><td class="topAlign">Wait for events if no pending events are available.</td></tr>
<tr><td class="topAlign"><tt>QEventLoop::DeferredDeletion</tt></td><td class="topAlign"><tt>0x10</tt></td><td class="topAlign">deprecated - do not use.</td></tr>
</table>
<p>The ProcessEventsFlags type is a typedef for <a href="qflags.html">QFlags</a>&lt;ProcessEventsFlag&gt;. It stores an OR combination of ProcessEventsFlag values.</p>
<p><b>See also </b><a href="qeventloop.html#processEvents">processEvents</a>().</p>
<!-- @@@ProcessEventsFlag -->
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<h2>Member Function Documentation</h2>
<!-- $$$QEventLoop[overload1]$$$QEventLoopQObject* -->
<h3 class="fn"><a name="QEventLoop"></a>QEventLoop::<span class="name">QEventLoop</span> ( <span class="type"><a href="qobject.html">QObject</a></span> * <i>parent</i> = 0 )</h3>
<p>Constructs an event loop object with the given <i>parent</i>.</p>
<!-- @@@QEventLoop -->
<!-- $$$~QEventLoop[overload1]$$$~QEventLoop -->
<h3 class="fn"><a name="dtor.QEventLoop"></a>QEventLoop::<span class="name">~QEventLoop</span> ()</h3>
<p>Destroys the event loop object.</p>
<!-- @@@~QEventLoop -->
<!-- $$$exec[overload1]$$$execProcessEventsFlags -->
<h3 class="fn"><a name="exec"></a><span class="type">int</span> QEventLoop::<span class="name">exec</span> ( <span class="type"><a href="qeventloop.html#ProcessEventsFlag-enum">ProcessEventsFlags</a></span> <i>flags</i> = AllEvents )</h3>
<p>Enters the main event loop and waits until <a href="qeventloop.html#exit">exit</a>() is called. Returns the value that was passed to <a href="qeventloop.html#exit">exit</a>().</p>
<p>If <i>flags</i> are specified, only events of the types allowed by the <i>flags</i> will be processed.</p>
<p>It is necessary to call this function to start event handling. The main event loop receives events from the window system and dispatches these to the application widgets.</p>
<p>Generally speaking, no user interaction can take place before calling exec(). As a special case, modal widgets like <a href="qmessagebox.html">QMessageBox</a> can be used before calling exec(), because modal widgets use their own local event loop.</p>
<p>To make your application perform idle processing (i.e&#x2e; executing a special function whenever there are no pending events), use a <a href="qtimer.html">QTimer</a> with 0 timeout. More sophisticated idle processing schemes can be achieved using <a href="qeventloop.html#processEvents">processEvents</a>().</p>
<p><b>See also </b><a href="qcoreapplication.html#quit">QApplication::quit</a>(), <a href="qeventloop.html#exit">exit</a>(), and <a href="qeventloop.html#processEvents">processEvents</a>().</p>
<!-- @@@exec -->
<!-- $$$exit[overload1]$$$exitint -->
<h3 class="fn"><a name="exit"></a><span class="type">void</span> QEventLoop::<span class="name">exit</span> ( <span class="type">int</span> <i>returnCode</i> = 0 )</h3>
<p>Tells the event loop to exit with a return code.</p>
<p>After this function has been called, the event loop returns from the call to <a href="qeventloop.html#exec">exec</a>(). The <a href="qeventloop.html#exec">exec</a>() function returns <i>returnCode</i>.</p>
<p>By convention, a <i>returnCode</i> of 0 means success, and any non-zero value indicates an error.</p>
<p>Note that unlike the C library function of the same name, this function <i>does</i> return to the caller -- it is event processing that stops.</p>
<p><b>See also </b><a href="qcoreapplication.html#quit">QCoreApplication::quit</a>(), <a href="qeventloop.html#quit">quit</a>(), and <a href="qeventloop.html#exec">exec</a>().</p>
<!-- @@@exit -->
<!-- $$$isRunning[overload1]$$$isRunning -->
<h3 class="fn"><a name="isRunning"></a><span class="type">bool</span> QEventLoop::<span class="name">isRunning</span> () const</h3>
<p>Returns true if the event loop is running; otherwise returns false. The event loop is considered running from the time when <a href="qeventloop.html#exec">exec</a>() is called until <a href="qeventloop.html#exit">exit</a>() is called.</p>
<p><b>See also </b><a href="qeventloop.html#exec">exec</a>() and <a href="qeventloop.html#exit">exit</a>().</p>
<!-- @@@isRunning -->
<!-- $$$processEvents[overload1]$$$processEventsProcessEventsFlags -->
<h3 class="fn"><a name="processEvents"></a><span class="type">bool</span> QEventLoop::<span class="name">processEvents</span> ( <span class="type"><a href="qeventloop.html#ProcessEventsFlag-enum">ProcessEventsFlags</a></span> <i>flags</i> = AllEvents )</h3>
<p>Processes pending events that match <i>flags</i> until there are no more events to process. Returns true if pending events were handled; otherwise returns false.</p>
<p>This function is especially useful if you have a long running operation and want to show its progress without allowing user input; i.e&#x2e; by using the <a href="qeventloop.html#ProcessEventsFlag-enum">ExcludeUserInputEvents</a> flag.</p>
<p>This function is simply a wrapper for <a href="qabstracteventdispatcher.html#processEvents">QAbstractEventDispatcher::processEvents</a>(). See the documentation for that function for details.</p>
<!-- @@@processEvents -->
<!-- $$$processEvents$$$processEventsProcessEventsFlagsint -->
<h3 class="fn"><a name="processEvents-2"></a><span class="type">void</span> QEventLoop::<span class="name">processEvents</span> ( <span class="type"><a href="qeventloop.html#ProcessEventsFlag-enum">ProcessEventsFlags</a></span> <i>flags</i>, <span class="type">int</span> <i>maxTime</i> )</h3>
<p>Process pending events that match <i>flags</i> for a maximum of <i>maxTime</i> milliseconds, or until there are no more events to process, whichever is shorter. This function is especially useful if you have a long running operation and want to show its progress without allowing user input, i.e&#x2e; by using the <a href="qeventloop.html#ProcessEventsFlag-enum">ExcludeUserInputEvents</a> flag.</p>
<p><b>Notes:</b></p>
<ul>
<li>This function does not process events continuously; it returns after all available events are processed.</li>
<li>Specifying the <a href="qeventloop.html#ProcessEventsFlag-enum">WaitForMoreEvents</a> flag makes no sense and will be ignored.</li>
</ul>
<!-- @@@processEvents -->
<!-- $$$quit[overload1]$$$quit -->
<h3 class="fn"><a name="quit"></a><span class="type">void</span> QEventLoop::<span class="name">quit</span> ()<tt> [slot]</tt></h3>
<p>Tells the event loop to exit normally.</p>
<p>Same as exit(0).</p>
<p><b>See also </b><a href="qcoreapplication.html#quit">QCoreApplication::quit</a>() and <a href="qeventloop.html#exit">exit</a>().</p>
<!-- @@@quit -->
<!-- $$$wakeUp[overload1]$$$wakeUp -->
<h3 class="fn"><a name="wakeUp"></a><span class="type">void</span> QEventLoop::<span class="name">wakeUp</span> ()</h3>
<p>Wakes up the event loop.</p>
<p><b>See also </b><a href="qabstracteventdispatcher.html#wakeUp">QAbstractEventDispatcher::wakeUp</a>().</p>
<!-- @@@wakeUp -->
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