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<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#xbelwriter-class-definition">XbelWriter Class Definition</a></li>
<li class="level1"><a href="#xbelwriter-class-implementation">XbelWriter Class Implementation</a></li>
<li class="level1"><a href="#xbelreader-class-definition">XbelReader Class Definition</a></li>
<li class="level1"><a href="#xbelreader-class-implementation">XbelReader Class Implementation</a></li>
<li class="level1"><a href="#mainwindow-class-definition">MainWindow Class Definition</a></li>
<li class="level1"><a href="#mainwindow-class-implementation">MainWindow Class Implementation</a></li>
<li class="level1"><a href="#function"><tt>main()</tt> Function</a></li>
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<h1 class="title">QXmlStream Bookmarks Example</h1>
<span class="subtitle"></span>
<!-- $$$xml/streambookmarks-description -->
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<p>Files:</p>
<ul>
<li><a href="xml-streambookmarks-mainwindow-cpp.html">xml/streambookmarks/mainwindow.cpp</a></li>
<li><a href="xml-streambookmarks-mainwindow-h.html">xml/streambookmarks/mainwindow.h</a></li>
<li><a href="xml-streambookmarks-xbelreader-cpp.html">xml/streambookmarks/xbelreader.cpp</a></li>
<li><a href="xml-streambookmarks-xbelreader-h.html">xml/streambookmarks/xbelreader.h</a></li>
<li><a href="xml-streambookmarks-xbelwriter-cpp.html">xml/streambookmarks/xbelwriter.cpp</a></li>
<li><a href="xml-streambookmarks-xbelwriter-h.html">xml/streambookmarks/xbelwriter.h</a></li>
<li><a href="xml-streambookmarks-main-cpp.html">xml/streambookmarks/main.cpp</a></li>
<li><a href="xml-streambookmarks-streambookmarks-pro.html">xml/streambookmarks/streambookmarks.pro</a></li>
</ul>
<p>The QXmlStream Bookmarks example provides a reader for XML Bookmark Exchange Language (XBEL) files using Qt's <a href="qxmlstreamreader.html">QXmlStreamReader</a> class for reading, and <a href="qxmlstreamwriter.html">QXmlStreamWriter</a> class for writing the files.<p class="centerAlign"><img src="images/xmlstreamexample-screenshot.png" alt="" /></p><a name="xbelwriter-class-definition"></a>
<h2>XbelWriter Class Definition</h2>
<p>The <tt>XbelWriter</tt> class contains a private instance of <a href="qxmlstreamwriter.html">QXmlStreamWriter</a>, which provides an XML writer with a streaming API. <tt>XbelWriter</tt> also has a reference to the <a href="qtreewidget.html">QTreeWidget</a> instance where the bookmark hierarchy is stored.</p>
<pre class="cpp"> <span class="keyword">class</span> XbelWriter
{
<span class="keyword">public</span>:
XbelWriter(<span class="type"><a href="qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget);
<span class="type">bool</span> writeFile(<span class="type"><a href="qiodevice.html">QIODevice</a></span> <span class="operator">*</span>device);
<span class="keyword">private</span>:
<span class="type">void</span> writeItem(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item);
<span class="type"><a href="qxmlstreamwriter.html">QXmlStreamWriter</a></span> xml;
<span class="type"><a href="qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget;
};</pre>
<a name="xbelwriter-class-implementation"></a>
<h2>XbelWriter Class Implementation</h2>
<p>The <tt>XbelWriter</tt> constructor accepts a <i>treeWidget</i> to initialize within its definition. We enable <a href="qxmlstreamwriter.html">QXmlStreamWriter</a>'s auto-formatting property to ensure line-breaks and indentations are added automatically to empty sections between elements, increasing readability as the data is split into several lines.</p>
<pre class="cpp"> XbelWriter<span class="operator">::</span>XbelWriter(<span class="type"><a href="qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget)
: treeWidget(treeWidget)
{
xml<span class="operator">.</span>setAutoFormatting(<span class="keyword">true</span>);
}</pre>
<p>The <tt>writeFile()</tt> function accepts a <a href="qiodevice.html">QIODevice</a> object and sets it using <tt>setDevice()</tt>. This function then writes the document type definition(DTD), the start element, the version, and <tt>treeWidget</tt>'s top-level items.</p>
<pre class="cpp"> <span class="type">bool</span> XbelWriter<span class="operator">::</span>writeFile(<span class="type"><a href="qiodevice.html">QIODevice</a></span> <span class="operator">*</span>device)
{
xml<span class="operator">.</span>setDevice(device);
xml<span class="operator">.</span>writeStartDocument();
xml<span class="operator">.</span>writeDTD(<span class="string">"<!DOCTYPE xbel>"</span>);
xml<span class="operator">.</span>writeStartElement(<span class="string">"xbel"</span>);
xml<span class="operator">.</span>writeAttribute(<span class="string">"version"</span><span class="operator">,</span> <span class="string">"1.0"</span>);
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> treeWidget<span class="operator">-</span><span class="operator">></span>topLevelItemCount(); <span class="operator">+</span><span class="operator">+</span>i)
writeItem(treeWidget<span class="operator">-</span><span class="operator">></span>topLevelItem(i));
xml<span class="operator">.</span>writeEndDocument();
<span class="keyword">return</span> <span class="keyword">true</span>;
}</pre>
<p>The <tt>writeItem()</tt> function accepts a <a href="qtreewidgetitem.html">QTreeWidgetItem</a> object and writes it to the stream, depending on its <tt>tagName</tt>, which can either be a "folder", "bookmark", or "separator".</p>
<pre class="cpp"> <span class="type">void</span> XbelWriter<span class="operator">::</span>writeItem(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item)
{
<span class="type"><a href="qstring.html">QString</a></span> tagName <span class="operator">=</span> item<span class="operator">-</span><span class="operator">></span>data(<span class="number">0</span><span class="operator">,</span> <span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>UserRole)<span class="operator">.</span>toString();
<span class="keyword">if</span> (tagName <span class="operator">=</span><span class="operator">=</span> <span class="string">"folder"</span>) {
<span class="type">bool</span> folded <span class="operator">=</span> <span class="operator">!</span>treeWidget<span class="operator">-</span><span class="operator">></span>isItemExpanded(item);
xml<span class="operator">.</span>writeStartElement(tagName);
xml<span class="operator">.</span>writeAttribute(<span class="string">"folded"</span><span class="operator">,</span> folded <span class="operator">?</span> <span class="string">"yes"</span> : <span class="string">"no"</span>);
xml<span class="operator">.</span>writeTextElement(<span class="string">"title"</span><span class="operator">,</span> item<span class="operator">-</span><span class="operator">></span>text(<span class="number">0</span>));
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> item<span class="operator">-</span><span class="operator">></span>childCount(); <span class="operator">+</span><span class="operator">+</span>i)
writeItem(item<span class="operator">-</span><span class="operator">></span>child(i));
xml<span class="operator">.</span>writeEndElement();
} <span class="keyword">else</span> <span class="keyword">if</span> (tagName <span class="operator">=</span><span class="operator">=</span> <span class="string">"bookmark"</span>) {
xml<span class="operator">.</span>writeStartElement(tagName);
<span class="keyword">if</span> (<span class="operator">!</span>item<span class="operator">-</span><span class="operator">></span>text(<span class="number">1</span>)<span class="operator">.</span>isEmpty())
xml<span class="operator">.</span>writeAttribute(<span class="string">"href"</span><span class="operator">,</span> item<span class="operator">-</span><span class="operator">></span>text(<span class="number">1</span>));
xml<span class="operator">.</span>writeTextElement(<span class="string">"title"</span><span class="operator">,</span> item<span class="operator">-</span><span class="operator">></span>text(<span class="number">0</span>));
xml<span class="operator">.</span>writeEndElement();
} <span class="keyword">else</span> <span class="keyword">if</span> (tagName <span class="operator">=</span><span class="operator">=</span> <span class="string">"separator"</span>) {
xml<span class="operator">.</span>writeEmptyElement(tagName);
}
}</pre>
<a name="xbelreader-class-definition"></a>
<h2>XbelReader Class Definition</h2>
<p>The <tt>XbelReader</tt> contains a private instance of <a href="qxmlstreamreader.html">QXmlStreamReader</a>, the companion class to <a href="qxmlstreamwriter.html">QXmlStreamWriter</a>. <tt>XbelReader</tt> also contains a reference to the <a href="qtreewidget.html">QTreeWidget</a> that is used to group the bookmarks according to their hierarchy.</p>
<pre class="cpp"> <span class="keyword">class</span> XbelReader
{
<span class="keyword">public</span>:
XbelReader(<span class="type"><a href="qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget);
<span class="type">bool</span> read(<span class="type"><a href="qiodevice.html">QIODevice</a></span> <span class="operator">*</span>device);
<span class="type"><a href="qstring.html">QString</a></span> errorString() <span class="keyword">const</span>;
<span class="keyword">private</span>:
<span class="type">void</span> readXBEL();
<span class="type">void</span> readTitle(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item);
<span class="type">void</span> readSeparator(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item);
<span class="type">void</span> readFolder(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item);
<span class="type">void</span> readBookmark(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item);
<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>createChildItem(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item);
<span class="type"><a href="qxmlstreamreader.html">QXmlStreamReader</a></span> xml;
<span class="type"><a href="qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget;
<span class="type"><a href="qicon.html">QIcon</a></span> folderIcon;
<span class="type"><a href="qicon.html">QIcon</a></span> bookmarkIcon;
};</pre>
<a name="xbelreader-class-implementation"></a>
<h2>XbelReader Class Implementation</h2>
<p>The <tt>XbelReader</tt> constructor accepts a <a href="qtreewidget.html">QTreeWidget</a> to initialize the <tt>treeWidget</tt> within its definition. A <a href="qstyle.html">QStyle</a> object is used to set <tt>treeWidget</tt>'s style property. The <tt>folderIcon</tt> is set to <a href="qicon.html#Mode-enum">QIcon::Normal</a> mode where the pixmap is only displayed when the user is not interacting with the icon. The <a href="qstyle.html#StandardPixmap-enum">QStyle::SP_DirClosedIcon</a>, <a href="qstyle.html#StandardPixmap-enum">QStyle::SP_DirOpenIcon</a>, and <a href="qstyle.html#StandardPixmap-enum">QStyle::SP_FileIcon</a> correspond to standard pixmaps that follow the style of your GUI.</p>
<pre class="cpp"> XbelReader<span class="operator">::</span>XbelReader(<span class="type"><a href="qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget)
: treeWidget(treeWidget)
{
<span class="type"><a href="qstyle.html">QStyle</a></span> <span class="operator">*</span>style <span class="operator">=</span> treeWidget<span class="operator">-</span><span class="operator">></span>style();
folderIcon<span class="operator">.</span>addPixmap(style<span class="operator">-</span><span class="operator">></span>standardPixmap(<span class="type"><a href="qstyle.html">QStyle</a></span><span class="operator">::</span>SP_DirClosedIcon)<span class="operator">,</span>
<span class="type"><a href="qicon.html">QIcon</a></span><span class="operator">::</span>Normal<span class="operator">,</span> <span class="type"><a href="qicon.html">QIcon</a></span><span class="operator">::</span>Off);
folderIcon<span class="operator">.</span>addPixmap(style<span class="operator">-</span><span class="operator">></span>standardPixmap(<span class="type"><a href="qstyle.html">QStyle</a></span><span class="operator">::</span>SP_DirOpenIcon)<span class="operator">,</span>
<span class="type"><a href="qicon.html">QIcon</a></span><span class="operator">::</span>Normal<span class="operator">,</span> <span class="type"><a href="qicon.html">QIcon</a></span><span class="operator">::</span>On);
bookmarkIcon<span class="operator">.</span>addPixmap(style<span class="operator">-</span><span class="operator">></span>standardPixmap(<span class="type"><a href="qstyle.html">QStyle</a></span><span class="operator">::</span>SP_FileIcon));
}</pre>
<p>The <tt>read()</tt> function accepts a <a href="qiodevice.html">QIODevice</a> and sets it using <a href="qxmlstreamreader.html#setDevice">setDevice()</a>. The actual process of reading only takes place if the file is a valid XBEL 1.0 file. Note that the XML input needs to be well-formed to be accepted by <a href="qxmlstreamreader.html">QXmlStreamReader</a>. Otherwise, the <a href="qxmlstreamreader.html#raiseError">raiseError()</a> function is used to display an error message. Since the XBEL reader is only concerned with reading XML elements, it makes extensive use of the <a href="qxmlstreamreader.html#readNextStartElement">readNextStartElement()</a> convenience function.</p>
<pre class="cpp"> <span class="type">bool</span> XbelReader<span class="operator">::</span>read(<span class="type"><a href="qiodevice.html">QIODevice</a></span> <span class="operator">*</span>device)
{
xml<span class="operator">.</span>setDevice(device);
<span class="keyword">if</span> (xml<span class="operator">.</span>readNextStartElement()) {
<span class="keyword">if</span> (xml<span class="operator">.</span>name() <span class="operator">=</span><span class="operator">=</span> <span class="string">"xbel"</span> <span class="operator">&</span><span class="operator">&</span> xml<span class="operator">.</span>attributes()<span class="operator">.</span>value(<span class="string">"version"</span>) <span class="operator">=</span><span class="operator">=</span> <span class="string">"1.0"</span>)
readXBEL();
<span class="keyword">else</span>
xml<span class="operator">.</span>raiseError(<span class="type"><a href="qobject.html">QObject</a></span><span class="operator">::</span>tr(<span class="string">"The file is not an XBEL version 1.0 file."</span>));
}
<span class="keyword">return</span> <span class="operator">!</span>xml<span class="operator">.</span>error();
}</pre>
<p>The <tt>errorString()</tt> function is used if an error occurred, in order to obtain a description of the error complete with line and column number information.</p>
<pre class="cpp"> <span class="type"><a href="qstring.html">QString</a></span> XbelReader<span class="operator">::</span>errorString() <span class="keyword">const</span>
{
<span class="keyword">return</span> <span class="type"><a href="qobject.html">QObject</a></span><span class="operator">::</span>tr(<span class="string">"%1\nLine %2, column %3"</span>)
<span class="operator">.</span>arg(xml<span class="operator">.</span>errorString())
<span class="operator">.</span>arg(xml<span class="operator">.</span>lineNumber())
<span class="operator">.</span>arg(xml<span class="operator">.</span>columnNumber());
}</pre>
<p>The <tt>readXBEL()</tt> function reads the name of a startElement and calls the appropriate function to read it, depending on whether if its a "folder", "bookmark" or "separator". Otherwise, it calls <a href="qxmlstreamreader.html#skipCurrentElement">skipCurrentElement()</a>. The <a href="qtglobal.html#Q_ASSERT">Q_ASSERT</a>() macro is used to provide a pre-condition for the function.</p>
<pre class="cpp"> <span class="type">void</span> XbelReader<span class="operator">::</span>readXBEL()
{
Q_ASSERT(xml<span class="operator">.</span>isStartElement() <span class="operator">&</span><span class="operator">&</span> xml<span class="operator">.</span>name() <span class="operator">=</span><span class="operator">=</span> <span class="string">"xbel"</span>);
<span class="keyword">while</span> (xml<span class="operator">.</span>readNextStartElement()) {
<span class="keyword">if</span> (xml<span class="operator">.</span>name() <span class="operator">=</span><span class="operator">=</span> <span class="string">"folder"</span>)
readFolder(<span class="number">0</span>);
<span class="keyword">else</span> <span class="keyword">if</span> (xml<span class="operator">.</span>name() <span class="operator">=</span><span class="operator">=</span> <span class="string">"bookmark"</span>)
readBookmark(<span class="number">0</span>);
<span class="keyword">else</span> <span class="keyword">if</span> (xml<span class="operator">.</span>name() <span class="operator">=</span><span class="operator">=</span> <span class="string">"separator"</span>)
readSeparator(<span class="number">0</span>);
<span class="keyword">else</span>
xml<span class="operator">.</span>skipCurrentElement();
}
}</pre>
<p>The <tt>readTitle()</tt> function reads the bookmark's title.</p>
<pre class="cpp"> <span class="type">void</span> XbelReader<span class="operator">::</span>readTitle(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item)
{
Q_ASSERT(xml<span class="operator">.</span>isStartElement() <span class="operator">&</span><span class="operator">&</span> xml<span class="operator">.</span>name() <span class="operator">=</span><span class="operator">=</span> <span class="string">"title"</span>);
<span class="type"><a href="qstring.html">QString</a></span> title <span class="operator">=</span> xml<span class="operator">.</span>readElementText();
item<span class="operator">-</span><span class="operator">></span>setText(<span class="number">0</span><span class="operator">,</span> title);
}</pre>
<p>The <tt>readSeparator()</tt> function creates a separator and sets its flags. The text is set to 30 "0xB7", the HEX equivalent for period. The element is then skipped using <a href="qxmlstreamreader.html#skipCurrentElement">skipCurrentElement()</a>.</p>
<pre class="cpp"> <span class="type">void</span> XbelReader<span class="operator">::</span>readSeparator(<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item)
{
Q_ASSERT(xml<span class="operator">.</span>isStartElement() <span class="operator">&</span><span class="operator">&</span> xml<span class="operator">.</span>name() <span class="operator">=</span><span class="operator">=</span> <span class="string">"separator"</span>);
<span class="type"><a href="qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>separator <span class="operator">=</span> createChildItem(item);
separator<span class="operator">-</span><span class="operator">></span>setFlags(item<span class="operator">-</span><span class="operator">></span>flags() <span class="operator">&</span> <span class="operator">~</span><span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>ItemIsSelectable);
separator<span class="operator">-</span><span class="operator">></span>setText(<span class="number">0</span><span class="operator">,</span> <span class="type"><a href="qstring.html">QString</a></span>(<span class="number">30</span><span class="operator">,</span> <span class="number">0xB7</span>));
xml<span class="operator">.</span>skipCurrentElement();
}</pre>
<a name="mainwindow-class-definition"></a>
<h2>MainWindow Class Definition</h2>
<p>The <tt>MainWindow</tt> class is a subclass of <a href="qmainwindow.html">QMainWindow</a>, with a <tt>File</tt> menu and a <tt>Help</tt> menu.</p>
<pre class="cpp"> <span class="keyword">class</span> MainWindow : <span class="keyword">public</span> <span class="type"><a href="qmainwindow.html">QMainWindow</a></span>
{
Q_OBJECT
<span class="keyword">public</span>:
MainWindow();
<span class="keyword">public</span> <span class="keyword">slots</span>:
<span class="type">void</span> open();
<span class="type">void</span> saveAs();
<span class="type">void</span> about();
<span class="keyword">private</span>:
<span class="type">void</span> createActions();
<span class="type">void</span> createMenus();
<span class="type"><a href="qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget;
<span class="type"><a href="qmenu.html">QMenu</a></span> <span class="operator">*</span>fileMenu;
<span class="type"><a href="qmenu.html">QMenu</a></span> <span class="operator">*</span>helpMenu;
<span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>openAct;
<span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>saveAsAct;
<span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>exitAct;
<span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>aboutAct;
<span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>aboutQtAct;
};</pre>
<a name="mainwindow-class-implementation"></a>
<h2>MainWindow Class Implementation</h2>
<p>The <tt>MainWindow</tt> constructor instantiates the <a href="qtreewidget.html">QTreeWidget</a> object, <tt>treeWidget</tt> and sets its header with a <a href="qstringlist.html">QStringList</a> object, <tt>labels</tt>. The constructor also invokes <tt>createActions()</tt> and <tt>createMenus()</tt> to set up the menus and their corresponding actions. The <tt>statusBar()</tt> is used to display the message "Ready" and the window's size is fixed to 480x320 pixels.</p>
<pre class="cpp"> MainWindow<span class="operator">::</span>MainWindow()
{
<span class="type"><a href="qstringlist.html">QStringList</a></span> labels;
labels <span class="operator"><</span><span class="operator"><</span> tr(<span class="string">"Title"</span>) <span class="operator"><</span><span class="operator"><</span> tr(<span class="string">"Location"</span>);
treeWidget <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qtreewidget.html">QTreeWidget</a></span>;
treeWidget<span class="operator">-</span><span class="operator">></span>header()<span class="operator">-</span><span class="operator">></span>setResizeMode(<span class="type"><a href="qheaderview.html">QHeaderView</a></span><span class="operator">::</span>Stretch);
treeWidget<span class="operator">-</span><span class="operator">></span>setHeaderLabels(labels);
setCentralWidget(treeWidget);
createActions();
createMenus();
statusBar()<span class="operator">-</span><span class="operator">></span>showMessage(tr(<span class="string">"Ready"</span>));
setWindowTitle(tr(<span class="string">"QXmlStream Bookmarks"</span>));
resize(<span class="number">480</span><span class="operator">,</span> <span class="number">320</span>);
}</pre>
<p>The <tt>open()</tt> function enables the user to open an XBEL file using <a href="qfiledialog.html#getOpenFileName">QFileDialog::getOpenFileName</a>(). A warning message is displayed along with the <tt>fileName</tt> and <tt>errorString</tt> if the file cannot be read or if there is a parse error.</p>
<pre class="cpp"> <span class="type">void</span> MainWindow<span class="operator">::</span>open()
{
<span class="preprocessor">#if defined(Q_OS_SYMBIAN)</span>
<span class="comment">// Look for bookmarks on the same drive where the application is installed to,</span>
<span class="comment">// if drive is not read only. QDesktopServices::DataLocation does this check,</span>
<span class="comment">// and returns writable drive.</span>
<span class="type"><a href="qstring.html">QString</a></span> bookmarksFolder <span class="operator">=</span>
<span class="type"><a href="qdesktopservices.html">QDesktopServices</a></span><span class="operator">::</span>storageLocation(<span class="type"><a href="qdesktopservices.html">QDesktopServices</a></span><span class="operator">::</span>DataLocation)<span class="operator">.</span>left(<span class="number">1</span>);
bookmarksFolder<span class="operator">.</span>append(<span class="string">":/Data/qt/saxbookmarks"</span>);
<span class="type"><a href="qdir.html">QDir</a></span><span class="operator">::</span>setCurrent(bookmarksFolder);
<span class="preprocessor">#endif</span>
<span class="type"><a href="qstring.html">QString</a></span> fileName <span class="operator">=</span>
<span class="type"><a href="qfiledialog.html">QFileDialog</a></span><span class="operator">::</span>getOpenFileName(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"Open Bookmark File"</span>)<span class="operator">,</span>
<span class="type"><a href="qdir.html">QDir</a></span><span class="operator">::</span>currentPath()<span class="operator">,</span>
tr(<span class="string">"XBEL Files (*.xbel *.xml)"</span>));
<span class="keyword">if</span> (fileName<span class="operator">.</span>isEmpty())
<span class="keyword">return</span>;
treeWidget<span class="operator">-</span><span class="operator">></span>clear();
<span class="type"><a href="qfile.html">QFile</a></span> file(fileName);
<span class="keyword">if</span> (<span class="operator">!</span>file<span class="operator">.</span>open(<span class="type"><a href="qfile.html">QFile</a></span><span class="operator">::</span>ReadOnly <span class="operator">|</span> <span class="type"><a href="qfile.html">QFile</a></span><span class="operator">::</span>Text)) {
<span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>warning(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"QXmlStream Bookmarks"</span>)<span class="operator">,</span>
tr(<span class="string">"Cannot read file %1:\n%2."</span>)
<span class="operator">.</span>arg(fileName)
<span class="operator">.</span>arg(file<span class="operator">.</span>errorString()));
<span class="keyword">return</span>;
}
XbelReader reader(treeWidget);
<span class="keyword">if</span> (<span class="operator">!</span>reader<span class="operator">.</span>read(<span class="operator">&</span>file)) {
<span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>warning(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"QXmlStream Bookmarks"</span>)<span class="operator">,</span>
tr(<span class="string">"Parse error in file %1:\n\n%2"</span>)
<span class="operator">.</span>arg(fileName)
<span class="operator">.</span>arg(reader<span class="operator">.</span>errorString()));
} <span class="keyword">else</span> {
statusBar()<span class="operator">-</span><span class="operator">></span>showMessage(tr(<span class="string">"File loaded"</span>)<span class="operator">,</span> <span class="number">2000</span>);
}
}</pre>
<p>The <tt>saveAs()</tt> function displays a <a href="qfiledialog.html">QFileDialog</a>, prompting the user for a <tt>fileName</tt> using <a href="qfiledialog.html#getSaveFileName">QFileDialog::getSaveFileName</a>(). Similar to the <tt>open()</tt> function, this function also displays a warning message if the file cannot be written to.</p>
<pre class="cpp"> <span class="type">void</span> MainWindow<span class="operator">::</span>saveAs()
{
<span class="preprocessor">#if defined(Q_OS_SYMBIAN)</span>
<span class="comment">// Look for bookmarks on the same drive where the application is installed to,</span>
<span class="comment">// if drive is not read only. QDesktopServices::DataLocation does this check,</span>
<span class="comment">// and returns writable drive.</span>
<span class="type"><a href="qstring.html">QString</a></span> bookmarksFolder <span class="operator">=</span>
<span class="type"><a href="qdesktopservices.html">QDesktopServices</a></span><span class="operator">::</span>storageLocation(<span class="type"><a href="qdesktopservices.html">QDesktopServices</a></span><span class="operator">::</span>DataLocation)<span class="operator">.</span>left(<span class="number">1</span>);
bookmarksFolder<span class="operator">.</span>append(<span class="string">":/Data/qt/saxbookmarks"</span>);
<span class="type"><a href="qdir.html">QDir</a></span><span class="operator">::</span>setCurrent(bookmarksFolder);
<span class="preprocessor">#endif</span>
<span class="type"><a href="qstring.html">QString</a></span> fileName <span class="operator">=</span>
<span class="type"><a href="qfiledialog.html">QFileDialog</a></span><span class="operator">::</span>getSaveFileName(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"Save Bookmark File"</span>)<span class="operator">,</span>
<span class="type"><a href="qdir.html">QDir</a></span><span class="operator">::</span>currentPath()<span class="operator">,</span>
tr(<span class="string">"XBEL Files (*.xbel *.xml)"</span>));
<span class="keyword">if</span> (fileName<span class="operator">.</span>isEmpty())
<span class="keyword">return</span>;
<span class="type"><a href="qfile.html">QFile</a></span> file(fileName);
<span class="keyword">if</span> (<span class="operator">!</span>file<span class="operator">.</span>open(<span class="type"><a href="qfile.html">QFile</a></span><span class="operator">::</span>WriteOnly <span class="operator">|</span> <span class="type"><a href="qfile.html">QFile</a></span><span class="operator">::</span>Text)) {
<span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>warning(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"QXmlStream Bookmarks"</span>)<span class="operator">,</span>
tr(<span class="string">"Cannot write file %1:\n%2."</span>)
<span class="operator">.</span>arg(fileName)
<span class="operator">.</span>arg(file<span class="operator">.</span>errorString()));
<span class="keyword">return</span>;
}
XbelWriter writer(treeWidget);
<span class="keyword">if</span> (writer<span class="operator">.</span>writeFile(<span class="operator">&</span>file))
statusBar()<span class="operator">-</span><span class="operator">></span>showMessage(tr(<span class="string">"File saved"</span>)<span class="operator">,</span> <span class="number">2000</span>);
}</pre>
<p>The <tt>about()</tt> function displays a <a href="qmessagebox.html">QMessageBox</a> with a brief description of the example.</p>
<pre class="cpp"> <span class="type">void</span> MainWindow<span class="operator">::</span>about()
{
<span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>about(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"About QXmlStream Bookmarks"</span>)<span class="operator">,</span>
tr(<span class="string">"The <b>QXmlStream Bookmarks</b> example demonstrates how to use Qt's "</span>
<span class="string">"QXmlStream classes to read and write XML documents."</span>));
}</pre>
<p>In order to implement the <tt>open()</tt>, <tt>saveAs()</tt>, <tt>exit()</tt>, <tt>about()</tt> and <tt>aboutQt()</tt> functions, we connect them to <a href="qaction.html">QAction</a> objects and add them to the <tt>fileMenu</tt> and <tt>helpMenu</tt>. The connections are as shown below:</p>
<pre class="cpp"> <span class="type">void</span> MainWindow<span class="operator">::</span>createActions()
{
openAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"&Open..."</span>)<span class="operator">,</span> <span class="keyword">this</span>);
openAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type"><a href="qkeysequence.html">QKeySequence</a></span><span class="operator">::</span>Open);
connect(openAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(open()));
saveAsAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"&Save As..."</span>)<span class="operator">,</span> <span class="keyword">this</span>);
saveAsAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type"><a href="qkeysequence.html">QKeySequence</a></span><span class="operator">::</span>SaveAs);
connect(saveAsAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(saveAs()));
exitAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"E&xit"</span>)<span class="operator">,</span> <span class="keyword">this</span>);
exitAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type"><a href="qkeysequence.html">QKeySequence</a></span><span class="operator">::</span>Quit);
connect(exitAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(close()));
aboutAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"&About"</span>)<span class="operator">,</span> <span class="keyword">this</span>);
connect(aboutAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(about()));
aboutQtAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"About &Qt"</span>)<span class="operator">,</span> <span class="keyword">this</span>);
connect(aboutQtAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> qApp<span class="operator">,</span> SLOT(aboutQt()));
}</pre>
<p>The <tt>createMenus()</tt> function creates the <tt>fileMenu</tt> and <tt>helpMenu</tt> and adds the <a href="qaction.html">QAction</a> objects to them in order to create the menu shown in the screenshot below:</p>
<table class="generic">
<tr valign="top" class="odd"><td ><img src="images/xmlstreamexample-filemenu.png" alt="" /></td><td ><img src="images/xmlstreamexample-helpmenu.png" alt="" /></td></tr>
</table>
<pre class="cpp"> <span class="type">void</span> MainWindow<span class="operator">::</span>createMenus()
{
fileMenu <span class="operator">=</span> menuBar()<span class="operator">-</span><span class="operator">></span>addMenu(tr(<span class="string">"&File"</span>));
fileMenu<span class="operator">-</span><span class="operator">></span>addAction(openAct);
fileMenu<span class="operator">-</span><span class="operator">></span>addAction(saveAsAct);
fileMenu<span class="operator">-</span><span class="operator">></span>addAction(exitAct);
menuBar()<span class="operator">-</span><span class="operator">></span>addSeparator();
helpMenu <span class="operator">=</span> menuBar()<span class="operator">-</span><span class="operator">></span>addMenu(tr(<span class="string">"&Help"</span>));
helpMenu<span class="operator">-</span><span class="operator">></span>addAction(aboutAct);
helpMenu<span class="operator">-</span><span class="operator">></span>addAction(aboutQtAct);
}</pre>
<a name="function"></a>
<h2><tt>main()</tt> Function</h2>
<p>The <tt>main()</tt> function instantiates <tt>MainWindow</tt> and invokes the <tt>show()</tt> function.</p>
<pre class="cpp"> <span class="type">int</span> main(<span class="type">int</span> argc<span class="operator">,</span> <span class="type">char</span> <span class="operator">*</span>argv<span class="operator">[</span><span class="operator">]</span>)
{
<span class="type"><a href="qapplication.html">QApplication</a></span> app(argc<span class="operator">,</span> argv);
MainWindow mainWin;
<span class="preprocessor">#ifdef Q_OS_SYMBIAN</span>
mainWin<span class="operator">.</span>showFullScreen();
<span class="preprocessor">#endif</span>
mainWin<span class="operator">.</span>show();
mainWin<span class="operator">.</span>open();
<span class="keyword">return</span> app<span class="operator">.</span>exec();
}</pre>
<p>See the <a href="http://pyxml.sourceforge.net/topics/xbel/">XML Bookmark Exchange Language Resource Page</a> for more information about XBEL files.</p>
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