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<td >Qt 5.12</td><td ><a href="qtnfc-index.html">Qt NFC</a></td><td >Annotated URL Example</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtnfc-index.html">Qt 5.12.6 Reference Documentation</a></td>
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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#annotatedurl-class-definition">AnnotatedUrl Class Definition</a></li>
<li class="level1"><a href="#annotatedurl-handler-implementation">AnnotatedUrl Handler Implementation</a></li>
<li class="level1"><a href="#running-the-example">Running the Example</a></li>
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<h1 class="title">Annotated URL Example</h1>
<span class="subtitle"></span>
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<p>An example showing reading from formatted NFC Data Exchange Format (NDEF) messages.</p>
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<div class="descr"> <a name="details"></a>
<p>The Annotated URL example displays the contents of specifically formatted NFC Data Exchange Format (NDEF) messages read from an NFC Tag. The NDEF message should contain a URI record, an optional <code>image/*</code> MIME record, and one or more localized Text records.</p>
<p>This is the initial state of the example:</p>
<p class="centerAlign"><img src="images/annotatedurl.png" alt="" /></p><p>In this example the NFC Tag used contains a text record. The UI gets updated accordingly to:</p>
<p class="centerAlign"><img src="images/annotatedurl2.png" alt="" /></p><a name="annotatedurl-class-definition"></a>
<h2 id="annotatedurl-class-definition">AnnotatedUrl Class Definition</h2>
<p>The <code>AnnotatedUrl</code> class wraps the <code>QNearFieldManager</code>, the class providing the NFC Tag detection functionality. NDEF messages are read by the <a href="qnearfieldmanager.html">QNearFieldManager</a> and forwarded to a handler contained in the <code>AnnotatedUrl</code> class. After parsing the NDEF message the class emits the signal AnnotatedUrl::annotatedUrl(const QUrl &url, const QString &title, const QPixmap &pixmap). The UI reacts to the signal displaying the contents of the NDEF message.</p>
<pre class="cpp">
<span class="keyword">class</span> AnnotatedUrl : <span class="keyword">public</span> <span class="type">QObject</span>
{
Q_OBJECT
<span class="keyword">public</span>:
<span class="keyword">explicit</span> AnnotatedUrl(<span class="type">QObject</span> <span class="operator">*</span>parent <span class="operator">=</span> <span class="number">0</span>);
<span class="operator">~</span>AnnotatedUrl();
<span class="keyword">signals</span>:
<span class="type">void</span> annotatedUrl(<span class="keyword">const</span> <span class="type">QUrl</span> <span class="operator">&</span>url<span class="operator">,</span> <span class="keyword">const</span> <span class="type">QString</span> <span class="operator">&</span>title<span class="operator">,</span> <span class="keyword">const</span> <span class="type">QPixmap</span> <span class="operator">&</span>pixmap);
<span class="keyword">public</span> <span class="keyword">slots</span>:
<span class="type">void</span> targetDetected(<span class="type"><a href="qnearfieldtarget.html">QNearFieldTarget</a></span> <span class="operator">*</span>target);
<span class="type">void</span> targetLost(<span class="type"><a href="qnearfieldtarget.html">QNearFieldTarget</a></span> <span class="operator">*</span>target);
<span class="type">void</span> handleMessage(<span class="keyword">const</span> <span class="type"><a href="qndefmessage.html">QNdefMessage</a></span> <span class="operator">&</span>message<span class="operator">,</span> <span class="type"><a href="qnearfieldtarget.html">QNearFieldTarget</a></span> <span class="operator">*</span>target);
<span class="type">void</span> handlePolledNdefMessage(<span class="type"><a href="qndefmessage.html">QNdefMessage</a></span> message);
<span class="keyword">private</span>:
<span class="type"><a href="qnearfieldmanager.html">QNearFieldManager</a></span> <span class="operator">*</span>manager;
};
</pre>
<a name="annotatedurl-handler-implementation"></a>
<h2 id="annotatedurl-handler-implementation">AnnotatedUrl Handler Implementation</h2>
<p>NFC messages read by the <code>QNearFieldManager</code> are forwarded to AnnotatedUrl::handleMessage. The callback signature details can be read in <a href="qnearfieldmanager.html#registerNdefMessageHandler">QNearFieldManager::registerNdefMessageHandler</a>.</p>
<pre class="cpp">
<span class="type">void</span> AnnotatedUrl<span class="operator">::</span>handleMessage(<span class="keyword">const</span> <span class="type"><a href="qndefmessage.html">QNdefMessage</a></span> <span class="operator">&</span>message<span class="operator">,</span> <span class="type"><a href="qnearfieldtarget.html">QNearFieldTarget</a></span> <span class="operator">*</span>target)
{
</pre>
<p>Because NFC messages are composed of several NDEF records, looping through all of the records allows the extraction of the 3 parameters to be displayed in the UI: the Uri, the Title and the Pixmap:</p>
<pre class="cpp">
<span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="qndefrecord.html">QNdefRecord</a></span> <span class="operator">&</span>record : message) {
<span class="keyword">if</span> (record<span class="operator">.</span>isRecordType<span class="operator"><</span><span class="type"><a href="qndefnfctextrecord.html">QNdefNfcTextRecord</a></span><span class="operator">></span>()) {
<span class="type"><a href="qndefnfctextrecord.html">QNdefNfcTextRecord</a></span> textRecord(record);
title <span class="operator">=</span> textRecord<span class="operator">.</span>text();
<span class="type">QLocale</span> locale(textRecord<span class="operator">.</span>locale());
} <span class="keyword">else</span> <span class="keyword">if</span> (record<span class="operator">.</span>isRecordType<span class="operator"><</span><span class="type"><a href="qndefnfcurirecord.html">QNdefNfcUriRecord</a></span><span class="operator">></span>()) {
<span class="type"><a href="qndefnfcurirecord.html">QNdefNfcUriRecord</a></span> uriRecord(record);
url <span class="operator">=</span> uriRecord<span class="operator">.</span>uri();
} <span class="keyword">else</span> <span class="keyword">if</span> (record<span class="operator">.</span>typeNameFormat() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qndefrecord.html">QNdefRecord</a></span><span class="operator">::</span>Mime <span class="operator">&</span><span class="operator">&</span>
record<span class="operator">.</span>type()<span class="operator">.</span>startsWith(<span class="string">"image/"</span>)) {
pixmap <span class="operator">=</span> <span class="type">QPixmap</span><span class="operator">::</span>fromImage(<span class="type">QImage</span><span class="operator">::</span>fromData(record<span class="operator">.</span>payload()));
}
</pre>
<p>Finally after having extracted the parameters of the NFC message the corresponding signal is emitted so that the UI can handle it.</p>
<pre class="cpp">
}
<span class="keyword">emit</span> annotatedUrl(url<span class="operator">,</span> title<span class="operator">,</span> pixmap);
}
</pre>
<a name="running-the-example"></a>
<h2 id="running-the-example">Running the Example</h2>
<p>To run the example from Qt Creator, open the <b>Welcome</b> mode and select the example from <b>Examples</b>. For more information, visit Building and Running an Example.</p>
<p>Files:</p>
<ul>
<li><a href="qtnfc-annotatedurl-annotatedurl-cpp.html">annotatedurl/annotatedurl.cpp</a></li>
<li><a href="qtnfc-annotatedurl-annotatedurl-h.html">annotatedurl/annotatedurl.h</a></li>
<li><a href="qtnfc-annotatedurl-annotatedurl-pro.html">annotatedurl/annotatedurl.pro</a></li>
<li><a href="qtnfc-annotatedurl-main-cpp.html">annotatedurl/main.cpp</a></li>
<li><a href="qtnfc-annotatedurl-mainwindow-cpp.html">annotatedurl/mainwindow.cpp</a></li>
<li><a href="qtnfc-annotatedurl-mainwindow-h.html">annotatedurl/mainwindow.h</a></li>
<li><a href="qtnfc-annotatedurl-mainwindow-ui.html">annotatedurl/mainwindow.ui</a></li>
</ul>
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<p><b>See also </b><a href="qtnfc-index.html">Qt NFC</a>.</p>
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