<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- qxmlstreambookmarks.qdoc --> <title>QXmlStream Bookmarks Example | Qt XML 5.12.6</title> <link rel="stylesheet" type="text/css" href="style/offline-simple.css" /> <script type="text/javascript"> document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css"); // loading style sheet breaks anchors that were jumped to before // so force jumping to anchor again setTimeout(function() { var anchor = location.hash; // need to jump to different anchor first (e.g. none) location.hash = "#"; setTimeout(function() { location.hash = anchor; }, 0); }, 0); </script> </head> <body> <div class="header" id="qtdocheader"> <div class="main"> <div class="main-rounded"> <div class="navigationbar"> <table><tr> <td >Qt 5.12</td><td ><a href="qtxml-index.html">Qt XML</a></td><td >QXmlStream Bookmarks Example</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right"><a href="qtxml-index.html">Qt 5.12.6 Reference Documentation</a></td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <div class="sidebar"> <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="#main-function"><code>main()</code> Function</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">QXmlStream Bookmarks Example</h1> <span class="subtitle"></span> <!-- $$$streambookmarks-brief --> <p>Demonstrates how to read and write to XBEL files.</p> <!-- @@@streambookmarks --> <!-- $$$streambookmarks-description --> <div class="descr"> <a name="details"></a> <p>The QXmlStream Bookmarks example provides a reader for XML Bookmark Exchange Language (XBEL) files using Qt's <a href="../qtcore/qxmlstreamreader.html">QXmlStreamReader</a> class for reading, and <a href="../qtcore/qxmlstreamwriter.html">QXmlStreamWriter</a> class for writing the files.</p> <p class="centerAlign"><img src="images/xmlstreamexample-screenshot.png" alt="" /></p><a name="xbelwriter-class-definition"></a> <h2 id="xbelwriter-class-definition">XbelWriter Class Definition</h2> <p>The <code>XbelWriter</code> class contains a private instance of <a href="../qtcore/qxmlstreamwriter.html">QXmlStreamWriter</a>, which provides an XML writer with a streaming API. <code>XbelWriter</code> also has a reference to the <a href="../qtwidgets/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>: <span class="keyword">explicit</span> XbelWriter(<span class="keyword">const</span> <span class="type"><a href="../qtwidgets/qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget); bool writeFile(<span class="type"><a href="../qtcore/qiodevice.html">QIODevice</a></span> <span class="operator">*</span>device); <span class="keyword">private</span>: <span class="type">void</span> writeItem(<span class="keyword">const</span> <span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item); <span class="type"><a href="../qtcore/qxmlstreamwriter.html">QXmlStreamWriter</a></span> xml; <span class="keyword">const</span> <span class="type"><a href="../qtwidgets/qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget; }; </pre> <a name="xbelwriter-class-implementation"></a> <h2 id="xbelwriter-class-implementation">XbelWriter Class Implementation</h2> <p>The <code>XbelWriter</code> constructor accepts a <i>treeWidget</i> to initialize within its definition. We enable <a href="../qtcore/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="keyword">const</span> <span class="type"><a href="../qtwidgets/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 <code>writeFile()</code> function accepts a <a href="../qtcore/qiodevice.html">QIODevice</a> object and sets it using <code>setDevice()</code>. This function then writes the document type definition(DTD), the start element, the version, and <code>treeWidget</code>'s top-level items.</p> <pre class="cpp"> bool XbelWriter<span class="operator">::</span>writeFile(<span class="type"><a href="../qtcore/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="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">"<!DOCTYPE xbel>"</span>)); xml<span class="operator">.</span>writeStartElement(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">"xbel"</span>)); xml<span class="operator">.</span>writeAttribute(XbelReader<span class="operator">::</span>versionAttribute()<span class="operator">,</span> <span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></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 <code>writeItem()</code> function accepts a <a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a> object and writes it to the stream, depending on its <code>tagName</code>, 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="keyword">const</span> <span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item) { <span class="type"><a href="../qtcore/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="../qtcore/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> QLatin1String(<span class="string">"folder"</span>)) { bool 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(XbelReader<span class="operator">::</span>foldedAttribute()<span class="operator">,</span> folded <span class="operator">?</span> yesValue() : noValue()); xml<span class="operator">.</span>writeTextElement(titleElement()<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> QLatin1String(<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(XbelReader<span class="operator">::</span>hrefAttribute()<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(titleElement()<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> QLatin1String(<span class="string">"separator"</span>)) { xml<span class="operator">.</span>writeEmptyElement(tagName); } } </pre> <a name="xbelreader-class-definition"></a> <h2 id="xbelreader-class-definition">XbelReader Class Definition</h2> <p>The <code>XbelReader</code> contains a private instance of <a href="../qtcore/qxmlstreamreader.html">QXmlStreamReader</a>, the companion class to <a href="../qtcore/qxmlstreamwriter.html">QXmlStreamWriter</a>. <code>XbelReader</code> also contains a reference to the <a href="../qtwidgets/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="../qtwidgets/qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget); bool read(<span class="type"><a href="../qtcore/qiodevice.html">QIODevice</a></span> <span class="operator">*</span>device); <span class="type"><a href="../qtcore/qstring.html">QString</a></span> errorString() <span class="keyword">const</span>; <span class="keyword">static</span> <span class="keyword">inline</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> versionAttribute() { <span class="keyword">return</span> <span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">"version"</span>); } <span class="keyword">static</span> <span class="keyword">inline</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> hrefAttribute() { <span class="keyword">return</span> <span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">"href"</span>); } <span class="keyword">static</span> <span class="keyword">inline</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> foldedAttribute() { <span class="keyword">return</span> <span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">"folded"</span>); } <span class="keyword">private</span>: <span class="type">void</span> readXBEL(); <span class="type">void</span> readTitle(<span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item); <span class="type">void</span> readSeparator(<span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item); <span class="type">void</span> readFolder(<span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item); <span class="type">void</span> readBookmark(<span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item); <span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>createChildItem(<span class="type"><a href="../qtwidgets/qtreewidgetitem.html">QTreeWidgetItem</a></span> <span class="operator">*</span>item); <span class="type"><a href="../qtcore/qxmlstreamreader.html">QXmlStreamReader</a></span> xml; <span class="type"><a href="../qtwidgets/qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget; <span class="type">QIcon</span> folderIcon; <span class="type">QIcon</span> bookmarkIcon; }; </pre> <a name="xbelreader-class-implementation"></a> <h2 id="xbelreader-class-implementation">XbelReader Class Implementation</h2> <p>The <code>XbelReader</code> constructor accepts a <a href="../qtwidgets/qtreewidget.html">QTreeWidget</a> to initialize the <code>treeWidget</code> within its definition. A <a href="../qtwidgets/qstyle.html">QStyle</a> object is used to set <code>treeWidget</code>'s style property. The <code>folderIcon</code> is set to QIcon::Normal mode where the pixmap is only displayed when the user is not interacting with the icon. The <a href="../qtwidgets/qstyle.html#StandardPixmap-enum">QStyle::SP_DirClosedIcon</a>, <a href="../qtwidgets/qstyle.html#StandardPixmap-enum">QStyle::SP_DirOpenIcon</a>, and <a href="../qtwidgets/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="../qtwidgets/qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget) : treeWidget(treeWidget) { <span class="type"><a href="../qtwidgets/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="../qtwidgets/qstyle.html">QStyle</a></span><span class="operator">::</span>SP_DirClosedIcon)<span class="operator">,</span> <span class="type">QIcon</span><span class="operator">::</span>Normal<span class="operator">,</span> <span class="type">QIcon</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="../qtwidgets/qstyle.html">QStyle</a></span><span class="operator">::</span>SP_DirOpenIcon)<span class="operator">,</span> <span class="type">QIcon</span><span class="operator">::</span>Normal<span class="operator">,</span> <span class="type">QIcon</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="../qtwidgets/qstyle.html">QStyle</a></span><span class="operator">::</span>SP_FileIcon)); } </pre> <p>The <code>read()</code> function accepts a <a href="../qtcore/qiodevice.html">QIODevice</a> and sets it using <a href="../qtcore/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="../qtcore/qxmlstreamreader.html">QXmlStreamReader</a>. Otherwise, the <a href="../qtcore/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="../qtcore/qxmlstreamreader.html#readNextStartElement">readNextStartElement()</a> convenience function.</p> <pre class="cpp"> bool XbelReader<span class="operator">::</span>read(<span class="type"><a href="../qtcore/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> QLatin1String(<span class="string">"xbel"</span>) <span class="operator">&</span><span class="operator">&</span> xml<span class="operator">.</span>attributes()<span class="operator">.</span>value(versionAttribute()) <span class="operator">=</span><span class="operator">=</span> QLatin1String(<span class="string">"1.0"</span>)) { readXBEL(); } <span class="keyword">else</span> { xml<span class="operator">.</span>raiseError(<span class="type"><a href="../qtcore/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 <code>errorString()</code> 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="../qtcore/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="../qtcore/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 <code>readXBEL()</code> 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="../qtcore/qxmlstreamreader.html#skipCurrentElement">skipCurrentElement()</a>. The <a href="../qtcore/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> QLatin1String(<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> QLatin1String(<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> QLatin1String(<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> QLatin1String(<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 <code>readTitle()</code> 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="../qtwidgets/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> QLatin1String(<span class="string">"title"</span>)); <span class="type"><a href="../qtcore/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 <code>readSeparator()</code> 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="../qtcore/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="../qtwidgets/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> QLatin1String(<span class="string">"separator"</span>)); <span class="type"><a href="../qtwidgets/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="../qtcore/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="../qtcore/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 id="mainwindow-class-definition">MainWindow Class Definition</h2> <p>The <code>MainWindow</code> class is a subclass of <a href="../qtwidgets/qmainwindow.html">QMainWindow</a>, with a <code>File</code> menu and a <code>Help</code> menu.</p> <pre class="cpp"> <span class="keyword">class</span> MainWindow : <span class="keyword">public</span> <span class="type"><a href="../qtwidgets/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="preprocessor">#if !defined(QT_NO_CONTEXTMENU) && !defined(QT_NO_CLIPBOARD)</span> <span class="type">void</span> onCustomContextMenuRequested(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qpoint.html">QPoint</a></span> <span class="operator">&</span>pos); <span class="preprocessor">#endif</span> <span class="keyword">private</span>: <span class="type">void</span> createMenus(); <span class="type"><a href="../qtwidgets/qtreewidget.html">QTreeWidget</a></span> <span class="operator">*</span>treeWidget; }; </pre> <a name="mainwindow-class-implementation"></a> <h2 id="mainwindow-class-implementation">MainWindow Class Implementation</h2> <p>The <code>MainWindow</code> constructor instantiates the <a href="../qtwidgets/qtreewidget.html">QTreeWidget</a> object, <code>treeWidget</code> and sets its header with a <a href="../qtcore/qstringlist.html">QStringList</a> object, <code>labels</code>. The constructor also invokes <code>createActions()</code> and <code>createMenus()</code> to set up the menus and their corresponding actions. The <code>statusBar()</code> 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="../qtcore/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="../qtwidgets/qtreewidget.html">QTreeWidget</a></span>; treeWidget<span class="operator">-</span><span class="operator">></span>header()<span class="operator">-</span><span class="operator">></span>setSectionResizeMode(<span class="type"><a href="../qtwidgets/qheaderview.html">QHeaderView</a></span><span class="operator">::</span>Stretch); treeWidget<span class="operator">-</span><span class="operator">></span>setHeaderLabels(labels); <span class="preprocessor">#if !defined(QT_NO_CONTEXTMENU) && !defined(QT_NO_CLIPBOARD)</span> treeWidget<span class="operator">-</span><span class="operator">></span>setContextMenuPolicy(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>CustomContextMenu); connect(treeWidget<span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtwidgets/qwidget.html">QWidget</a></span><span class="operator">::</span>customContextMenuRequested<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>MainWindow<span class="operator">::</span>onCustomContextMenuRequested); <span class="preprocessor">#endif</span> setCentralWidget(treeWidget); 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>)); <span class="keyword">const</span> <span class="type"><a href="../qtcore/qsize.html">QSize</a></span> availableSize <span class="operator">=</span> <span class="type"><a href="../qtwidgets/qapplication.html">QApplication</a></span><span class="operator">::</span>desktop()<span class="operator">-</span><span class="operator">></span>availableGeometry(<span class="keyword">this</span>)<span class="operator">.</span>size(); resize(availableSize<span class="operator">.</span>width() <span class="operator">/</span> <span class="number">2</span><span class="operator">,</span> availableSize<span class="operator">.</span>height() <span class="operator">/</span> <span class="number">3</span>); } </pre> <p>The <code>open()</code> function enables the user to open an XBEL file using <a href="../qtwidgets/qfiledialog.html#getOpenFileName">QFileDialog::getOpenFileName</a>(). A warning message is displayed along with the <code>fileName</code> and <code>errorString</code> 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="type"><a href="../qtcore/qstring.html">QString</a></span> fileName <span class="operator">=</span> <span class="type"><a href="../qtwidgets/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="../qtcore/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="../qtcore/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="../qtcore/qfile.html">QFile</a></span><span class="operator">::</span>ReadOnly <span class="operator">|</span> <span class="type"><a href="../qtcore/qfile.html">QFile</a></span><span class="operator">::</span>Text)) { <span class="type"><a href="../qtwidgets/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(<span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>toNativeSeparators(fileName)<span class="operator">,</span> 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="../qtwidgets/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(<span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>toNativeSeparators(fileName)<span class="operator">,</span> 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 <code>saveAs()</code> function displays a <a href="../qtwidgets/qfiledialog.html">QFileDialog</a>, prompting the user for a <code>fileName</code> using <a href="../qtwidgets/qfiledialog.html#getSaveFileName">QFileDialog::getSaveFileName</a>(). Similar to the <code>open()</code> 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="type"><a href="../qtcore/qstring.html">QString</a></span> fileName <span class="operator">=</span> <span class="type"><a href="../qtwidgets/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="../qtcore/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="../qtcore/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="../qtcore/qfile.html">QFile</a></span><span class="operator">::</span>WriteOnly <span class="operator">|</span> <span class="type"><a href="../qtcore/qfile.html">QFile</a></span><span class="operator">::</span>Text)) { <span class="type"><a href="../qtwidgets/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(<span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>toNativeSeparators(fileName)<span class="operator">,</span> 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 <code>about()</code> function displays a <a href="../qtwidgets/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="../qtwidgets/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 <code>open()</code>, <code>saveAs()</code>, <code>exit()</code>, <code>about()</code> and <code>aboutQt()</code> functions, we connect them to <a href="../qtwidgets/qaction.html">QAction</a> objects and add them to the <code>fileMenu</code> and <code>helpMenu</code>. The connections are as shown below:</p> <pre class="cpp"> <span class="type">void</span> MainWindow<span class="operator">::</span>createMenus() { <span class="type"><a href="../qtwidgets/qmenu.html">QMenu</a></span> <span class="operator">*</span>fileMenu <span class="operator">=</span> menuBar()<span class="operator">-</span><span class="operator">></span>addMenu(tr(<span class="string">"&File"</span>)); <span class="type"><a href="../qtwidgets/qaction.html">QAction</a></span> <span class="operator">*</span>openAct <span class="operator">=</span> fileMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"&Open..."</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>MainWindow<span class="operator">::</span>open); openAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type">QKeySequence</span><span class="operator">::</span>Open); <span class="type"><a href="../qtwidgets/qaction.html">QAction</a></span> <span class="operator">*</span>saveAsAct <span class="operator">=</span> fileMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"&Save As..."</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>MainWindow<span class="operator">::</span>saveAs); saveAsAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type">QKeySequence</span><span class="operator">::</span>SaveAs); <span class="type"><a href="../qtwidgets/qaction.html">QAction</a></span> <span class="operator">*</span>exitAct <span class="operator">=</span> fileMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"E&xit"</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtwidgets/qwidget.html">QWidget</a></span><span class="operator">::</span>close); exitAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type">QKeySequence</span><span class="operator">::</span>Quit); menuBar()<span class="operator">-</span><span class="operator">></span>addSeparator(); <span class="type"><a href="../qtwidgets/qmenu.html">QMenu</a></span> <span class="operator">*</span>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(tr(<span class="string">"&About"</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>MainWindow<span class="operator">::</span>about); helpMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"About &Qt"</span>)<span class="operator">,</span> <a href="../qtwidgets/qapplication.html#qApp">qApp</a><span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtcore/qcoreapplication.html">QCoreApplication</a></span><span class="operator">::</span>quit); } </pre> <p>The <code>createMenus()</code> function creates the <code>fileMenu</code> and <code>helpMenu</code> and adds the <a href="../qtwidgets/qaction.html">QAction</a> objects to them in order to create the menu shown in the screenshot below:</p> <div class="table"><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></div> <pre class="cpp"> <span class="type">void</span> MainWindow<span class="operator">::</span>createMenus() { <span class="type"><a href="../qtwidgets/qmenu.html">QMenu</a></span> <span class="operator">*</span>fileMenu <span class="operator">=</span> menuBar()<span class="operator">-</span><span class="operator">></span>addMenu(tr(<span class="string">"&File"</span>)); <span class="type"><a href="../qtwidgets/qaction.html">QAction</a></span> <span class="operator">*</span>openAct <span class="operator">=</span> fileMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"&Open..."</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>MainWindow<span class="operator">::</span>open); openAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type">QKeySequence</span><span class="operator">::</span>Open); <span class="type"><a href="../qtwidgets/qaction.html">QAction</a></span> <span class="operator">*</span>saveAsAct <span class="operator">=</span> fileMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"&Save As..."</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>MainWindow<span class="operator">::</span>saveAs); saveAsAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type">QKeySequence</span><span class="operator">::</span>SaveAs); <span class="type"><a href="../qtwidgets/qaction.html">QAction</a></span> <span class="operator">*</span>exitAct <span class="operator">=</span> fileMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"E&xit"</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtwidgets/qwidget.html">QWidget</a></span><span class="operator">::</span>close); exitAct<span class="operator">-</span><span class="operator">></span>setShortcuts(<span class="type">QKeySequence</span><span class="operator">::</span>Quit); menuBar()<span class="operator">-</span><span class="operator">></span>addSeparator(); <span class="type"><a href="../qtwidgets/qmenu.html">QMenu</a></span> <span class="operator">*</span>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(tr(<span class="string">"&About"</span>)<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>MainWindow<span class="operator">::</span>about); helpMenu<span class="operator">-</span><span class="operator">></span>addAction(tr(<span class="string">"About &Qt"</span>)<span class="operator">,</span> <a href="../qtwidgets/qapplication.html#qApp">qApp</a><span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtcore/qcoreapplication.html">QCoreApplication</a></span><span class="operator">::</span>quit); } </pre> <a name="main-function"></a> <h2 id="main-function"><code>main()</code> Function</h2> <p>The <code>main()</code> function instantiates <code>MainWindow</code> and invokes the <code>show()</code> 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="../qtwidgets/qapplication.html">QApplication</a></span> app(argc<span class="operator">,</span> argv); MainWindow mainWin; 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> <p>Files:</p> <ul> <li><a href="qtxml-streambookmarks-main-cpp.html">streambookmarks/main.cpp</a></li> <li><a href="qtxml-streambookmarks-mainwindow-cpp.html">streambookmarks/mainwindow.cpp</a></li> <li><a href="qtxml-streambookmarks-mainwindow-h.html">streambookmarks/mainwindow.h</a></li> <li><a href="qtxml-streambookmarks-streambookmarks-pro.html">streambookmarks/streambookmarks.pro</a></li> <li><a href="qtxml-streambookmarks-xbelreader-cpp.html">streambookmarks/xbelreader.cpp</a></li> <li><a href="qtxml-streambookmarks-xbelreader-h.html">streambookmarks/xbelreader.h</a></li> <li><a href="qtxml-streambookmarks-xbelwriter-cpp.html">streambookmarks/xbelwriter.cpp</a></li> <li><a href="qtxml-streambookmarks-xbelwriter-h.html">streambookmarks/xbelwriter.h</a></li> </ul> </div> <!-- @@@streambookmarks --> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2019 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.<br/> 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.<br/> 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. </p> </div> </body> </html>