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<h1 class="title">Extending QML - Extension Objects Example</h1>
<span class="subtitle"></span>
<!-- $$$referenceexamples/extended-brief -->
<p>Extension Objects.</p>
<!-- @@@referenceexamples/extended -->
<!-- $$$referenceexamples/extended-description -->
<div class="descr"> <a name="details"></a>
<p>This example builds on:</p>
<ul>
<li><a href="qtqml-referenceexamples-adding-example.html">Extending QML - Adding Types Example</a></li>
</ul>
<p>Shows how to use <a href="qqmlengine.html#qmlRegisterExtendedType">qmlRegisterExtendedType()</a> to provide an <a href="qtqml-cppintegration-definetypes.html#registering-extension-objects">extension object</a> to a QLineEdit without modifying or subclassing it.</p>
<p>Firstly, the LineEditExtension class is registered with the QML system as an extension of QLineEdit:</p>
<pre class="cpp">
qmlRegisterExtendedType<span class="operator"><</span><span class="type">QLineEdit</span><span class="operator">,</span> LineEditExtension<span class="operator">></span>(<span class="string">"People"</span><span class="operator">,</span> <span class="number">1</span><span class="operator">,</span><span class="number">0</span><span class="operator">,</span> <span class="string">"QLineEdit"</span>);
</pre>
<p>The QML engine then instantiates a QLineEdit:</p>
<pre class="cpp">
<span class="type"><a href="qqmlengine.html">QQmlEngine</a></span> engine;
<span class="type"><a href="qqmlcomponent.html">QQmlComponent</a></span> component(<span class="operator">&</span>engine<span class="operator">,</span> <span class="type">QUrl</span>(<span class="string">"qrc:example.qml"</span>));
<span class="type">QLineEdit</span> <span class="operator">*</span>edit <span class="operator">=</span> qobject_cast<span class="operator"><</span><span class="type">QLineEdit</span> <span class="operator">*</span><span class="operator">></span>(component<span class="operator">.</span>create());
</pre>
<p>In QML, a property is set on the line edit that only exists in the LineEditExtension class:</p>
<pre class="qml">
QLineEdit {
leftMargin: 20
}
</pre>
<p>The extension type performs calls on the QLineEdit that otherwise will not be accessible to the QML engine.</p>
<p>Files:</p>
<ul>
<li><a href="qtqml-referenceexamples-extended-example-qml.html">referenceexamples/extended/example.qml</a></li>
<li><a href="qtqml-referenceexamples-extended-extended-pro.html">referenceexamples/extended/extended.pro</a></li>
<li><a href="qtqml-referenceexamples-extended-extended-qrc.html">referenceexamples/extended/extended.qrc</a></li>
<li><a href="qtqml-referenceexamples-extended-lineedit-cpp.html">referenceexamples/extended/lineedit.cpp</a></li>
<li><a href="qtqml-referenceexamples-extended-lineedit-h.html">referenceexamples/extended/lineedit.h</a></li>
<li><a href="qtqml-referenceexamples-extended-main-cpp.html">referenceexamples/extended/main.cpp</a></li>
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