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<?xml version="1.0" encoding="iso-8859-1"?>
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<html><head><title>QEventLoop Class Reference</title><style>h3.fn,span.fn { margin-left: 1cm; text-indent: -1cm }
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</style></head><body><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr /><td align="left" valign="top" width="32"><img align="left" border="0" height="32" src="images/rb-logo.png" width="32" /></td><td width="1">  </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="modules.html"><font color="#004faf">Modules</font></a></td></table><h1 align="center">QEventLoop Class Reference<br /><sup><sup>[<a href="qtcore.html">QtCore</a> module]</sup></sup></h1><p>The QEventLoop class provides a means of entering and leaving an
event loop. <a href="#details">More...</a></p>
<p>Inherits <a href="qobject.html">QObject</a>.</p><h3>Types</h3><ul><li><div class="fn" />enum <b><a href="qeventloop.html#ProcessEventsFlag-enum">ProcessEventsFlag</a></b> { AllEvents, ExcludeUserInputEvents, ExcludeSocketNotifiers, WaitForMoreEvents, X11ExcludeTimers, DeferredDeletion }</li><li><div class="fn" />class <b><a href="qeventloop-processeventsflags.html">ProcessEventsFlags</a></b></li></ul><h3>Methods</h3><ul><li><div class="fn" /><b><a href="qeventloop.html#QEventLoop">__init__</a></b> (<i>self</i>, QObject <i>parent</i> = None)</li><li><div class="fn" />int <b><a href="qeventloop.html#exec">exec_</a></b> (<i>self</i>, ProcessEventsFlags <i>flags</i> = QEventLoop.AllEvents)</li><li><div class="fn" /><b><a href="qeventloop.html#exit">exit</a></b> (<i>self</i>, int <i>returnCode</i> = 0)</li><li><div class="fn" />bool <b><a href="qeventloop.html#isRunning">isRunning</a></b> (<i>self</i>)</li><li><div class="fn" />bool <b><a href="qeventloop.html#processEvents">processEvents</a></b> (<i>self</i>, ProcessEventsFlags <i>flags</i> = QEventLoop.AllEvents)</li><li><div class="fn" /><b><a href="qeventloop.html#processEvents-2">processEvents</a></b> (<i>self</i>, ProcessEventsFlags <i>flags</i>, int <i>maximumTime</i>)</li><li><div class="fn" /><b><a href="qeventloop.html#quit">quit</a></b> (<i>self</i>)</li><li><div class="fn" /><b><a href="qeventloop.html#wakeUp">wakeUp</a></b> (<i>self</i>)</li></ul><a name="details" /><hr /><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>
<hr /><h2>Type Documentation</h2><h3 class="fn"><a name="ProcessEventsFlag-enum" />QEventLoop.ProcessEventsFlag</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 class="odd" valign="top">
<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><ProcessEventsFlag>. It stores an OR
combination of ProcessEventsFlag values.</p>
<p><b>See also</b> <a href="qeventloop.html#processEvents">processEvents</a>().</p>
<hr /><h2>Method Documentation</h2><h3 class="fn"><a name="QEventLoop" />QEventLoop.__init__ (<i>self</i>, <a href="qobject.html">QObject</a> <i>parent</i> = None)</h3><p>The <i>parent</i> argument, if not None, causes <i>self</i> to be owned by Qt instead of PyQt.</p><p>Constructs an event loop object with the given
<i>parent</i>.</p>
<h3 class="fn"><a name="exec" />int QEventLoop.exec_ (<i>self</i>, <a href="qeventloop-processeventsflags.html">ProcessEventsFlags</a> <i>flags</i> = QEventLoop.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. 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>
<h3 class="fn"><a name="exit" />QEventLoop.exit (<i>self</i>, int <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>
<h3 class="fn"><a name="isRunning" />bool QEventLoop.isRunning (<i>self</i>)</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>
<h3 class="fn"><a name="processEvents" />bool QEventLoop.processEvents (<i>self</i>, <a href="qeventloop-processeventsflags.html">ProcessEventsFlags</a> <i>flags</i> = QEventLoop.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. 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>
<h3 class="fn"><a name="processEvents-2" />QEventLoop.processEvents (<i>self</i>, <a href="qeventloop-processeventsflags.html">ProcessEventsFlags</a> <i>flags</i>, int <i>maximumTime</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. 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>
<h3 class="fn"><a name="quit" />QEventLoop.quit (<i>self</i>)</h3><p>This method is also a Qt slot with the C++ signature <tt>void quit()</tt>.</p><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>
<h3 class="fn"><a name="wakeUp" />QEventLoop.wakeUp (<i>self</i>)</h3><p>Wakes up the event loop.</p>
<p><b>See also</b> <a href="qabstracteventdispatcher.html#wakeUp">QAbstractEventDispatcher.wakeUp</a>().</p>
<address><hr /><div align="center"><table border="0" cellspacing="0" width="100%"><tr class="address"><td align="left" width="25%">PyQt 4.12.1 for X11</td><td align="center" width="50%">Copyright © <a href="http://www.riverbankcomputing.com">Riverbank Computing Ltd</a> and <a href="http://www.qt.io">The Qt Company</a> 2015</td><td align="right" width="25%">Qt 4.8.7</td></tr></table></div></address></body></html>
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