Outliner to show use of DOM

This example presents a small outliner program to show the basic usage of the DOM classes. The format of the outlines is the OPML format as described in http://www.opml.org/spec.

This example shows how to load a DOM tree from an XML file and how to traverse it.

Sample XML file (todos.opml):

<?xml version="1.0" encoding="ISO-8859-1"?>
<opml version="1.0">
    <head>
        <title>Todo List</title>
        <dateCreated>Tue, 31 Oct 2000 17:00:17 CET</dateCreated>
        <dateModified>Tue, 31 Oct 2000 17:00:17 CET</dateModified>
        <ownerName>Arthur Dent</ownerName>
        <ownerEmail>info@trolltech.com</ownerEmail>
    </head>
    <body>
        <outline text="Background">
            <outline text="This is an example todo list."/>
        </outline>
        <outline text="Books to read">
            <outline text="Science Fiction">
                <outline text="Philip K. Dick">
                    <outline text="Do Androids Dream of Electical Sheep?"/>
                    <outline text="The Three Stigmata of Palmer Eldritch"/>
                </outline>
                <outline text="Robert A. Heinlein">
                    <outline text="Stranger in a Strange Land"/>
                </outline>
                <outline text="Isaac Asimov">
                    <outline text="Foundation and Empire"/>
                </outline>
            </outline>
            <outline text="Qt Books (in English)">
                <outline text="Dalheimer: Programming with Qt"/>
                <outline text="Griffith: KDE 2/Qt Programming Bible"/>
                <outline text="Hughes: Linux Rapid Application Development"/>
                <outline text="Solin: Qt Programming in 24 hours"/>
                <outline text="Ward: Qt 2 Programming for Linux and Windows 2000"/>
            </outline>
        </outline>
        <outline text="Shopping list">
            <outline text="General">
                <outline text="Towel"/>
                <outline text="Hair dryer"/>
                <outline text="Underpants"/>
            </outline>
            <outline text="For Sunday">
                <outline text="Beef"/>
                <outline text="Rice"/>
                <outline text="Carrots"/>
                <outline text="Beans"/>
                <outline text="Beer"/>
                <outline text="Wine"/>
                <outline text="Orange juice"/>
            </outline>
        </outline>
        <outline text="Write a letter to Ford">
        </outline>
    </body>
</opml>

Header file (outlinetree.h):

/****************************************************************************
** $Id: $
**
** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#ifndef OUTLINETREE_H
#define OUTLINETREE_H

#include <qlistview.h>
#include <qdom.h>

class OutlineTree : public QListView
{
    Q_OBJECT

public:
    OutlineTree( const QString fileName, QWidget *parent = 0, const char *name = 0 );
    ~OutlineTree();

private:
    QDomDocument domTree;
    void getHeaderInformation( const QDomElement &header );
    void buildTree( QListViewItem *parentItem, const QDomElement &parentElement );
};

#endif // OUTLINETREE_H

Implementation (outlinetree.cpp):

/****************************************************************************
** $Id: $
**
** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include "outlinetree.h"
#include <qfile.h>
#include <qmessagebox.h>

OutlineTree::OutlineTree( const QString fileName, QWidget *parent, const char *name )
    : QListView( parent, name )
{
    // div. configuration of the list view
    addColumn( "Outlines" );
    setSorting( -1 );
    setRootIsDecorated( TRUE );

    // read the XML file and create DOM tree
    QFile opmlFile( fileName );
    if ( !opmlFile.open( IO_ReadOnly ) ) {
        QMessageBox::critical( 0,
                tr( "Critical Error" ),
                tr( "Cannot open file %1" ).arg( fileName ) );
        return;
    }
    if ( !domTree.setContent( &opmlFile ) ) {
        QMessageBox::critical( 0,
                tr( "Critical Error" ),
                tr( "Parsing error for file %1" ).arg( fileName ) );
        opmlFile.close();
        return;
    }
    opmlFile.close();

    // get the header information from the DOM
    QDomElement root = domTree.documentElement();
    QDomNode node;
    node = root.firstChild();
    while ( !node.isNull() ) {
        if ( node.isElement() && node.nodeName() == "head" ) {
            QDomElement header = node.toElement();
            getHeaderInformation( header );
            break;
        }
        node = node.nextSibling();
    }
    // create the tree view out of the DOM
    node = root.firstChild();
    while ( !node.isNull() ) {
        if ( node.isElement() && node.nodeName() == "body" ) {
            QDomElement body = node.toElement();
            buildTree( 0, body );
            break;
        }
        node = node.nextSibling();
    }
}

OutlineTree::~OutlineTree()
{
}

void OutlineTree::getHeaderInformation( const QDomElement &header )
{
    // visit all children of the header element and look if you can make
    // something with it
    QDomNode node = header.firstChild();
    while ( !node.isNull() ) {
        if ( node.isElement() ) {
            // case for the different header entries
            if ( node.nodeName() == "title" ) {
                QDomText textChild = node.firstChild().toText();
                if ( !textChild.isNull() ) {
                    setColumnText( 0, textChild.nodeValue() );
                }
            }
        }
        node = node.nextSibling();
    }
}

void OutlineTree::buildTree( QListViewItem *parentItem, const QDomElement &parentElement )
{
    QListViewItem *thisItem = 0;
    QDomNode node = parentElement.firstChild();
    while ( !node.isNull() ) {
        if ( node.isElement() && node.nodeName() == "outline" ) {
            // add a new list view item for the outline
            if ( parentItem == 0 )
                thisItem = new QListViewItem( this, thisItem );
            else
                thisItem = new QListViewItem( parentItem, thisItem );
            thisItem->setText( 0, node.toElement().attribute( "text" ) );
            // recursive build of the tree
            buildTree( thisItem, node.toElement() );
        }
        node = node.nextSibling();
    }
}

Main (main.cpp):

/****************************************************************************
** $Id: $
**
** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include <qapplication.h>
#include "outlinetree.h"

int main( int argc, char **argv )
{
    QApplication a( argc, argv );

    OutlineTree outline( "todos.opml" );
    a.setMainWidget( &outline );
    outline.show();

    return a.exec();
}

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