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<?xml version="1.0" encoding="UTF-8"?>
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<title>Qt 4.8: Extending QML - Adding Types Example</title>
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<a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
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<li>Extending QML - Adding Types Example</li>
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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#declare-the-person-class">Declare the Person class</a></li>
<li class="level1"><a href="#define-the-person-class">Define the Person class</a></li>
<li class="level1"><a href="#running-the-example">Running the example</a></li>
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<h1 class="title">Extending QML - Adding Types Example</h1>
<span class="subtitle"></span>
<!-- $$$declarative/cppextensions/referenceexamples/adding-description -->
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<p>Files:</p>
<ul>
<li><a href="declarative-cppextensions-referenceexamples-adding-example-qml.html">declarative/cppextensions/referenceexamples/adding/example.qml</a></li>
<li><a href="declarative-cppextensions-referenceexamples-adding-person-cpp.html">declarative/cppextensions/referenceexamples/adding/person.cpp</a></li>
<li><a href="declarative-cppextensions-referenceexamples-adding-person-h.html">declarative/cppextensions/referenceexamples/adding/person.h</a></li>
<li><a href="declarative-cppextensions-referenceexamples-adding-main-cpp.html">declarative/cppextensions/referenceexamples/adding/main.cpp</a></li>
<li><a href="declarative-cppextensions-referenceexamples-adding-adding-pro.html">declarative/cppextensions/referenceexamples/adding/adding.pro</a></li>
<li><a href="declarative-cppextensions-referenceexamples-adding-adding-qrc.html">declarative/cppextensions/referenceexamples/adding/adding.qrc</a></li>
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<p>The Adding Types Example shows how to add a new element type, <tt>Person</tt>, to QML.<p>The <tt>Person</tt> type can be used from QML like this:</p>
<pre class="qml"> import People 1.0
<span class="type">Person</span> {
<span class="name">name</span>: <span class="string">"Bob Jones"</span>
<span class="name">shoeSize</span>: <span class="number">12</span>
}</pre>
<a name="declare-the-person-class"></a>
<h2>Declare the Person class</h2>
<p>All QML elements map to C++ types. Here we declare a basic C++ Person class with the two properties we want accessible on the QML type - name and shoeSize. Although in this example we use the same name for the C++ class as the QML element, the C++ class can be named differently, or appear in a namespace.</p>
<pre class="cpp"> <span class="keyword">class</span> Person : <span class="keyword">public</span> <span class="type"><a href="qobject.html">QObject</a></span>
{
Q_OBJECT
Q_PROPERTY(<span class="type"><a href="qstring.html">QString</a></span> name READ name WRITE setName)
Q_PROPERTY(<span class="type">int</span> shoeSize READ shoeSize WRITE setShoeSize)
<span class="keyword">public</span>:
Person(<span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>parent <span class="operator">=</span> <span class="number">0</span>);
<span class="type"><a href="qstring.html">QString</a></span> name() <span class="keyword">const</span>;
<span class="type">void</span> setName(<span class="keyword">const</span> <span class="type"><a href="qstring.html">QString</a></span> <span class="operator">&</span>);
<span class="type">int</span> shoeSize() <span class="keyword">const</span>;
<span class="type">void</span> setShoeSize(<span class="type">int</span>);
<span class="keyword">private</span>:
<span class="type"><a href="qstring.html">QString</a></span> m_name;
<span class="type">int</span> m_shoeSize;
};</pre>
<a name="define-the-person-class"></a>
<h2>Define the Person class</h2>
<pre class="cpp"> Person<span class="operator">::</span>Person(<span class="type"><a href="qobject.html">QObject</a></span> <span class="operator">*</span>parent)
: <span class="type"><a href="qobject.html">QObject</a></span>(parent)<span class="operator">,</span> m_shoeSize(<span class="number">0</span>)
{
}
<span class="type"><a href="qstring.html">QString</a></span> Person<span class="operator">::</span>name() <span class="keyword">const</span>
{
<span class="keyword">return</span> m_name;
}
<span class="type">void</span> Person<span class="operator">::</span>setName(<span class="keyword">const</span> <span class="type"><a href="qstring.html">QString</a></span> <span class="operator">&</span>n)
{
m_name <span class="operator">=</span> n;
}
<span class="type">int</span> Person<span class="operator">::</span>shoeSize() <span class="keyword">const</span>
{
<span class="keyword">return</span> m_shoeSize;
}
<span class="type">void</span> Person<span class="operator">::</span>setShoeSize(<span class="type">int</span> s)
{
m_shoeSize <span class="operator">=</span> s;
}</pre>
<p>The Person class implementation is quite basic. The property accessors simply return members of the object instance.</p>
<p>The <tt>main.cpp</tt> file also calls the <tt>qmlRegisterType()</tt> function to register the <tt>Person</tt> type with QML as a type in the People library version 1.0, and defines the mapping between the C++ and QML class names.</p>
<a name="running-the-example"></a>
<h2>Running the example</h2>
<p>The main.cpp file in the example includes a simple shell application that loads and runs the QML snippet shown at the beginning of this page.</p>
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