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Breadcrumbs go here --> <li><a href="all-examples.html">Examples</a></li> <li>QXmlStream Bookmarks Example</li> </ul> </div> <div class="toolbuttons toolblock"> <ul> <li id="smallA" class="t_button">A</li> <li id="medA" class="t_button active">A</li> <li id="bigA" class="t_button">A</li> <li id="print" class="t_button"><a href="javascript:this.print();"> <span>Print</span></a></li> </ul> </div> </div> <div class="content mainContent"> <div class="toc"> <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> </ul> </div> <h1 class="title">QXmlStream Bookmarks Example</h1> <span class="subtitle"></span> <!-- $$$xml/streambookmarks-description --> <div class="descr"> <a name="details"></a> <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> </div> <!-- @@@xml/streambookmarks --> </div> </div> </div> <div class="ft"> <span></span> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2015 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.</p> <br /> <p> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.</p> <p> Documentation sources may be obtained from <a href="http://www.qt-project.org"> www.qt-project.org</a>.</p> <br /> <p> Qt and respective logos are trademarks of The Qt Company Ltd in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. <a title="Privacy Policy" href="http://en.gitorious.org/privacy_policy/">Privacy Policy</a></p> </div> <script src="scripts/functions.js" type="text/javascript"></script> </body> </html>