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<td >Qt 5.12</td><td ><a href="qtqml-index.html">Qt QML</a></td><td ><a href="qtqml-module.html">C++ Classes</a></td><td >QQmlIncubationController</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtqml-index.html">Qt 5.12.6 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#protected-functions">Protected Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QQmlIncubationController Class</h1>
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<p><a href="qqmlincubationcontroller.html">QQmlIncubationController</a> instances drive the progress of QQmlIncubators. <a href="#details">More...</a></p>
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<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QQmlIncubationController></span>
</td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += qml</td></tr></table></div><ul>
<li><a href="qqmlincubationcontroller-members.html">List of all members, including inherited members</a></li>
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<a name="public-functions"></a>
<h2 id="public-functions">Public Functions</h2>
<div class="table"><table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qqmlincubationcontroller.html#QQmlIncubationController">QQmlIncubationController</a></b>()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> QQmlEngine *</td><td class="memItemRight bottomAlign"><b><a href="qqmlincubationcontroller.html#engine">engine</a></b>() const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qqmlincubationcontroller.html#incubateFor">incubateFor</a></b>(int <i>msecs</i>)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qqmlincubationcontroller.html#incubateWhile">incubateWhile</a></b>(volatile bool *<i>flag</i>, int <i>msecs</i> = 0)</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> int </td><td class="memItemRight bottomAlign"><b><a href="qqmlincubationcontroller.html#incubatingObjectCount">incubatingObjectCount</a></b>() const</td></tr>
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<h2 id="protected-functions">Protected Functions</h2>
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<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qqmlincubationcontroller.html#incubatingObjectCountChanged">incubatingObjectCountChanged</a></b>(int <i>incubatingObjectCount</i>)</td></tr>
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<a name="details"></a>
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<h2 id="details">Detailed Description</h2>
<p><a href="qqmlincubationcontroller.html">QQmlIncubationController</a> instances drive the progress of QQmlIncubators.</p>
<p>In order to behave asynchronously and not introduce stutters or freezes in an application, the process of creating objects a QQmlIncubators must be driven only during the application's idle time. <a href="qqmlincubationcontroller.html">QQmlIncubationController</a> allows the application to control exactly when, how often and for how long this processing occurs.</p>
<p>A <a href="qqmlincubationcontroller.html">QQmlIncubationController</a> derived instance should be created and set on a <a href="qqmlengine.html">QQmlEngine</a> by calling the <a href="qqmlengine.html#setIncubationController">QQmlEngine::setIncubationController</a>() method. Processing is then controlled by calling the <a href="qqmlincubationcontroller.html#incubateFor">QQmlIncubationController::incubateFor</a>() or <a href="qqmlincubationcontroller.html#incubateWhile">QQmlIncubationController::incubateWhile</a>() methods as dictated by the application's requirements.</p>
<p>For example, this is an example of a incubation controller that will incubate for a maximum of 5 milliseconds out of every 16 milliseconds.</p>
<pre class="cpp">
<span class="keyword">class</span> PeriodicIncubationController : <span class="keyword">public</span> <span class="type">QObject</span><span class="operator">,</span>
<span class="keyword">public</span> <span class="type"><a href="qqmlincubationcontroller.html#QQmlIncubationController">QQmlIncubationController</a></span>
{
<span class="keyword">public</span>:
PeriodicIncubationController() {
startTimer(<span class="number">16</span>);
}
<span class="keyword">protected</span>:
<span class="type">void</span> timerEvent(<span class="type">QTimerEvent</span> <span class="operator">*</span>) override {
incubateFor(<span class="number">5</span>);
}
};
</pre>
<p>Although the previous example would work, it is not optimal. Real world incubation controllers should try and maximize the amount of idle time they consume - rather than a static amount like 5 milliseconds - while not disturbing the application.</p>
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<h2>Member Function Documentation</h2>
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<h3 class="fn" id="QQmlIncubationController"><a name="QQmlIncubationController"></a>QQmlIncubationController::<span class="name">QQmlIncubationController</span>()</h3>
<p>Create a new incubation controller.</p>
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<h3 class="fn" id="engine"><a name="engine"></a><span class="type"><a href="qqmlengine.html">QQmlEngine</a></span> *QQmlIncubationController::<span class="name">engine</span>() const</h3>
<p>Return the <a href="qqmlengine.html">QQmlEngine</a> this incubation controller is set on, or 0 if it has not been set on any engine.</p>
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<h3 class="fn" id="incubateFor"><a name="incubateFor"></a><span class="type">void</span> QQmlIncubationController::<span class="name">incubateFor</span>(<span class="type">int</span> <i>msecs</i>)</h3>
<p>Incubate objects for <i>msecs</i>, or until there are no more objects to incubate.</p>
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<h3 class="fn" id="incubateWhile"><a name="incubateWhile"></a><span class="type">void</span> QQmlIncubationController::<span class="name">incubateWhile</span>(<span class="type">volatile</span> <span class="type">bool</span> *<i>flag</i>, <span class="type">int</span> <i>msecs</i> = 0)</h3>
<p>Incubate objects while the bool pointed to by <i>flag</i> is true, or until there are no more objects to incubate, or up to <i>msecs</i> if <i>msecs</i> is not zero.</p>
<p>Generally this method is used in conjunction with a thread or a UNIX signal that sets the bool pointed to by <i>flag</i> to false when it wants incubation to be interrupted.</p>
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<h3 class="fn" id="incubatingObjectCount"><a name="incubatingObjectCount"></a><span class="type">int</span> QQmlIncubationController::<span class="name">incubatingObjectCount</span>() const</h3>
<p>Return the number of objects currently incubating.</p>
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<h3 class="fn" id="incubatingObjectCountChanged"><a name="incubatingObjectCountChanged"></a><code>[virtual protected] </code><span class="type">void</span> QQmlIncubationController::<span class="name">incubatingObjectCountChanged</span>(<span class="type">int</span> <i>incubatingObjectCount</i>)</h3>
<p>Called when the number of incubating objects changes. <i>incubatingObjectCount</i> is the new number of incubating objects.</p>
<p>The default implementation does nothing.</p>
<!-- @@@incubatingObjectCountChanged -->
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