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Please review the following information to ensure ** the GNU Free Documentation License version 1.3 requirements ** will be met: http://www.gnu.org/copyleft/fdl.html. ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \example streambookmarks \title QXmlStream Bookmarks Example \brief Demonstrates how to read and write to XBEL files \ingroup xml-examples The QXmlStream Bookmarks example provides a reader for XML Bookmark Exchange Language (XBEL) files using Qt's QXmlStreamReader class for reading, and QXmlStreamWriter class for writing the files. \image xmlstreamexample-screenshot.png \section1 XbelWriter Class Definition The \c XbelWriter class contains a private instance of QXmlStreamWriter, which provides an XML writer with a streaming API. \c XbelWriter also has a reference to the QTreeWidget instance where the bookmark hierarchy is stored. \snippet streambookmarks/xbelwriter.h 0 \section1 XbelWriter Class Implementation The \c XbelWriter constructor accepts a \a treeWidget to initialize within its definition. We enable \l{QXmlStreamWriter}'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. \snippet streambookmarks/xbelwriter.cpp 0 The \c writeFile() function accepts a QIODevice object and sets it using \c setDevice(). This function then writes the document type definition(DTD), the start element, the version, and \c{treeWidget}'s top-level items. \snippet streambookmarks/xbelwriter.cpp 1 The \c writeItem() function accepts a QTreeWidgetItem object and writes it to the stream, depending on its \c tagName, which can either be a "folder", "bookmark", or "separator". \snippet streambookmarks/xbelwriter.cpp 2 \section1 XbelReader Class Definition The \c XbelReader contains a private instance of QXmlStreamReader, the companion class to QXmlStreamWriter. \c XbelReader also contains a reference to the QTreeWidget that is used to group the bookmarks according to their hierarchy. \snippet streambookmarks/xbelreader.h 0 \section1 XbelReader Class Implementation The \c XbelReader constructor accepts a QTreeWidget to initialize the \c treeWidget within its definition. A QStyle object is used to set \c{treeWidget}'s style property. The \c folderIcon is set to QIcon::Normal mode where the pixmap is only displayed when the user is not interacting with the icon. The QStyle::SP_DirClosedIcon, QStyle::SP_DirOpenIcon, and QStyle::SP_FileIcon correspond to standard pixmaps that follow the style of your GUI. \snippet streambookmarks/xbelreader.cpp 0 The \c read() function accepts a QIODevice and sets it using \l{QXmlStreamReader::}{setDevice()}. 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 QXmlStreamReader. Otherwise, the \l{QXmlStreamReader::}{raiseError()} 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 \l{QXmlStreamReader::}{readNextStartElement()} convenience function. \snippet streambookmarks/xbelreader.cpp 1 The \c errorString() function is used if an error occurred, in order to obtain a description of the error complete with line and column number information. \snippet streambookmarks/xbelreader.cpp 2 The \c readXBEL() 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 \l{QXmlStreamReader::}{skipCurrentElement()}. The Q_ASSERT() macro is used to provide a pre-condition for the function. \snippet streambookmarks/xbelreader.cpp 3 The \c readTitle() function reads the bookmark's title. \snippet streambookmarks/xbelreader.cpp 4 The \c readSeparator() 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 \l{QXmlStreamReader::}{skipCurrentElement()}. \snippet streambookmarks/xbelreader.cpp 5 \section1 MainWindow Class Definition The \c MainWindow class is a subclass of QMainWindow, with a \c File menu and a \c Help menu. \snippet streambookmarks/mainwindow.h 0 \section1 MainWindow Class Implementation The \c MainWindow constructor instantiates the QTreeWidget object, \c treeWidget and sets its header with a QStringList object, \c labels. The constructor also invokes \c createActions() and \c createMenus() to set up the menus and their corresponding actions. The \c statusBar() is used to display the message "Ready" and the window's size is fixed to 480x320 pixels. \snippet streambookmarks/mainwindow.cpp 0 The \c open() function enables the user to open an XBEL file using QFileDialog::getOpenFileName(). A warning message is displayed along with the \c fileName and \c errorString if the file cannot be read or if there is a parse error. \snippet streambookmarks/mainwindow.cpp 1 The \c saveAs() function displays a QFileDialog, prompting the user for a \c fileName using QFileDialog::getSaveFileName(). Similar to the \c open() function, this function also displays a warning message if the file cannot be written to. \snippet streambookmarks/mainwindow.cpp 2 The \c about() function displays a QMessageBox with a brief description of the example. \snippet streambookmarks/mainwindow.cpp 3 In order to implement the \c open(), \c saveAs(), \c exit(), \c about() and \c aboutQt() functions, we connect them to QAction objects and add them to the \c fileMenu and \c helpMenu. The connections are as shown below: \snippet streambookmarks/mainwindow.cpp 4 The \c createMenus() function creates the \c fileMenu and \c helpMenu and adds the QAction objects to them in order to create the menu shown in the screenshot below: \table \row \li \inlineimage xmlstreamexample-filemenu.png \li \inlineimage xmlstreamexample-helpmenu.png \endtable \snippet streambookmarks/mainwindow.cpp 5 \section1 \c{main()} Function The \c main() function instantiates \c MainWindow and invokes the \c show() function. \snippet streambookmarks/main.cpp 0 See the \l{http://pyxml.sourceforge.net/topics/xbel/} {XML Bookmark Exchange Language Resource Page} for more information about XBEL files. */