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Breadcrumbs go here --> <li><a href="modules.html">Modules</a></li> <li><a href="qttest.html">QtTest</a></li> <li>QSignalSpy</li> </ul> </div> <div class="toolbuttons toolblock"> <ul> <li id="smallA" class="t_button">A</li> <li id="medA" class="t_button active">A</li> <li id="bigA" class="t_button">A</li> <li id="print" class="t_button"><a href="javascript:this.print();"> <span>Print</span></a></li> </ul> </div> </div> <div class="content mainContent"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#public-functions">Public Functions</a></li> <li class="level1"><a href="#details">Detailed Description</a></li> </ul> </div> <h1 class="title">QSignalSpy Class Reference</h1> <!-- $$$QSignalSpy-brief --> <p>The QSignalSpy class enables introspection of signal emission. <a href="#details">More...</a></p> <!-- @@@QSignalSpy --> <pre class="cpp"> <span class="preprocessor">#include <QSignalSpy></span></pre><p><b>Inherits: </b><a href="qobject.html">QObject</a> and <a href="qlist.html">QList<QList<QVariant> ></a>.</p> <ul> <li><a href="qsignalspy-members.html">List of all members, including inherited members</a></li> </ul> <a name="public-functions"></a> <h2>Public Functions</h2> <table class="alignedsummary"> <tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qsignalspy.html#QSignalSpy">QSignalSpy</a></b> ( QObject * <i>object</i>, const char * <i>signal</i> )</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qsignalspy.html#isValid">isValid</a></b> () const</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> QByteArray </td><td class="memItemRight bottomAlign"><b><a href="qsignalspy.html#signal">signal</a></b> () const</td></tr> </table> <ul> <li class="fn">29 public functions inherited from <a href="qobject.html#public-functions">QObject</a></li> <li class="fn">67 public functions inherited from <a href="qlist.html#public-functions">QList</a></li> </ul> <h3>Additional Inherited Members</h3> <ul> <li class="fn">1 property inherited from <a href="qobject.html#properties">QObject</a></li> <li class="fn">1 public slot inherited from <a href="qobject.html#public-slots">QObject</a></li> <li class="fn">1 signal inherited from <a href="qobject.html#signals">QObject</a></li> <li class="fn">7 static public members inherited from <a href="qobject.html#static-public-members">QObject</a></li> <li class="fn">3 static public members inherited from <a href="qlist.html#static-public-members">QList</a></li> <li class="fn">8 protected functions inherited from <a href="qobject.html#protected-functions">QObject</a></li> </ul> <a name="details"></a> <!-- $$$QSignalSpy-description --> <div class="descr"> <h2>Detailed Description</h2> <p>The QSignalSpy class enables introspection of signal emission.</p> <p>QSignalSpy can connect to any signal of any object and records its emission. QSignalSpy itself is a list of <a href="qvariant.html">QVariant</a> lists. Each emission of the signal will append one item to the list, containing the arguments of the signal.</p> <p>The following example records all signal emissions for the <tt>clicked()</tt> signal of a <a href="qcheckbox.html">QCheckBox</a>:</p> <pre class="cpp"> <span class="type"><a href="qcheckbox.html">QCheckBox</a></span> <span class="operator">*</span>box <span class="operator">=</span> <span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>; <span class="type">QSignalSpy</span> spy(box<span class="operator">,</span> SIGNAL(clicked(<span class="type">bool</span>))); <span class="comment">// do something that triggers the signal</span> box<span class="operator">-</span><span class="operator">></span>animateClick(); <a href="qtest.html#QCOMPARE">QCOMPARE</a>(spy<span class="operator">.</span>count()<span class="operator">,</span> <span class="number">1</span>); <span class="comment">// make sure the signal was emitted exactly one time</span> <span class="type"><a href="qlist.html">QList</a></span><span class="operator"><</span><span class="type"><a href="qvariant.html">QVariant</a></span><span class="operator">></span> arguments <span class="operator">=</span> spy<span class="operator">.</span><a href="qlist.html#takeFirst">takeFirst</a>(); <span class="comment">// take the first signal</span> <a href="qtest.html#QVERIFY">QVERIFY</a>(arguments<span class="operator">.</span>at(<span class="number">0</span>)<span class="operator">.</span>toBool() <span class="operator">=</span><span class="operator">=</span> <span class="keyword">true</span>); <span class="comment">// verify the first argument</span></pre> <p><tt>spy.takeFirst()</tt> returns the arguments for the first emitted signal, as a list of <a href="qvariant.html">QVariant</a> objects. The <tt>clicked()</tt> signal has a single bool argument, which is stored as the first entry in the list of arguments.</p> <p>The example below catches a signal from a custom object:</p> <pre class="cpp"> <span class="type">QSignalSpy</span> spy(myCustomObject<span class="operator">,</span> SIGNAL(mySignal(<span class="type">int</span><span class="operator">,</span> <span class="type"><a href="qstring.html">QString</a></span><span class="operator">,</span> <span class="type">double</span>))); myCustomObject<span class="operator">-</span><span class="operator">></span>doSomething(); <span class="comment">// trigger emission of the signal</span> <span class="type"><a href="qlist.html">QList</a></span><span class="operator"><</span><span class="type"><a href="qvariant.html">QVariant</a></span><span class="operator">></span> arguments <span class="operator">=</span> spy<span class="operator">.</span><a href="qlist.html#takeFirst">takeFirst</a>(); <a href="qtest.html#QVERIFY">QVERIFY</a>(arguments<span class="operator">.</span>at(<span class="number">0</span>)<span class="operator">.</span>type() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qvariant.html">QVariant</a></span><span class="operator">::</span>Int); <a href="qtest.html#QVERIFY">QVERIFY</a>(arguments<span class="operator">.</span>at(<span class="number">1</span>)<span class="operator">.</span>type() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qvariant.html">QVariant</a></span><span class="operator">::</span><span class="type"><a href="qstring.html">QString</a></span>); <a href="qtest.html#QVERIFY">QVERIFY</a>(arguments<span class="operator">.</span>at(<span class="number">2</span>)<span class="operator">.</span>type() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qvariant.html">QVariant</a></span><span class="operator">::</span><span class="type">double</span>);</pre> <p><b>Note:</b> Non-standard data types need to be registered, using the <a href="qmetatype.html#qRegisterMetaType">qRegisterMetaType</a>() function, before you can create a QSignalSpy. For example:</p> <pre class="cpp"> <a href="qmetatype.html#qRegisterMetaType">qRegisterMetaType</a><span class="operator"><</span><span class="type"><a href="qmodelindex.html">QModelIndex</a></span><span class="operator">></span>(<span class="string">"QModelIndex"</span>); <span class="type">QSignalSpy</span> spy(<span class="operator">&</span>model<span class="operator">,</span> SIGNAL(whatever(<span class="type"><a href="qmodelindex.html">QModelIndex</a></span>)));</pre> <p>To retrieve the <tt>QModelIndex</tt>, you can use qvariant_cast:</p> <pre class="cpp"> <span class="comment">// get the first argument from the first received signal:</span> <span class="type"><a href="qmodelindex.html">QModelIndex</a></span> result <span class="operator">=</span> qvariant_cast<span class="operator"><</span><span class="type"><a href="qmodelindex.html">QModelIndex</a></span><span class="operator">></span>(spy<span class="operator">.</span>at(<span class="number">0</span>)<span class="operator">.</span>at(<span class="number">0</span>));</pre> </div> <!-- @@@QSignalSpy --> <div class="func"> <h2>Member Function Documentation</h2> <!-- $$$QSignalSpy[overload1]$$$QSignalSpyQObject*constchar* --> <h3 class="fn"><a name="QSignalSpy"></a>QSignalSpy::<span class="name">QSignalSpy</span> ( <span class="type"><a href="qobject.html">QObject</a></span> * <i>object</i>, const <span class="type">char</span> * <i>signal</i> )</h3> <p>Constructs a new <a href="qsignalspy.html">QSignalSpy</a> that listens for emissions of the <i>signal</i> from the <a href="qobject.html">QObject</a> <i>object</i>. Neither <i>signal</i> nor <i>object</i> can be null.</p> <p>Example:</p> <pre class="cpp"> <span class="type"><a href="qsignalspy.html">QSignalSpy</a></span> spy(myPushButton<span class="operator">,</span> SIGNAL(clicked(<span class="type">bool</span>)));</pre> <!-- @@@QSignalSpy --> <!-- $$$isValid[overload1]$$$isValid --> <h3 class="fn"><a name="isValid"></a><span class="type">bool</span> QSignalSpy::<span class="name">isValid</span> () const</h3> <p>Returns true if the signal spy listens to a valid signal, otherwise false.</p> <!-- @@@isValid --> <!-- $$$signal[overload1]$$$signal --> <h3 class="fn"><a name="signal"></a><span class="type"><a href="qbytearray.html">QByteArray</a></span> QSignalSpy::<span class="name">signal</span> () const</h3> <p>Returns the normalized signal the spy is currently listening to.</p> <!-- @@@signal --> </div> </div> </div> </div> <div class="ft"> <span></span> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2015 The Qt Company Ltd. 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