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# treemodel.cpp Example File
itemviews/simpletreemodel/treemodel.cpp

        /****************************************************************************
        **
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        **
        ** This file is part of the documentation of the Qt Toolkit.
        **
        ** This file may be distributed and/or modified under the terms of the
    ** GNU General Public License version 2 as published by the Free Software
    ** Foundation and appearing in the file LICENSE.GPL included in the
    ** packaging of this file.
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    ** information about Qt Commercial License Agreements.
    ** See http://www.trolltech.com/gpl/ for GPL licensing information.
    **
    ** Contact info@trolltech.com if any conditions of this licensing are
    ** not clear to you.
        **
        ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
        ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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        /*
            treemodel.cpp

            Provides a simple tree model to show how to create and use hierarchical
            models.
        */

        #include <QtGui>

        #include "treeitem.h"
        #include "treemodel.h"

        TreeModel::TreeModel(const QString &data, QObject *parent)
            : QAbstractItemModel(parent)
        {
            QList<QVariant> rootData;
            rootData << "Title" << "Summary";
            rootItem = new TreeItem(rootData);
            setupModelData(data.split(QString("\n")), rootItem);
        }

        TreeModel::~TreeModel()
        {
            delete rootItem;
        }

        int TreeModel::columnCount(const QModelIndex &parent) const
        {
            if (parent.isValid())
                return static_cast<TreeItem*>(parent.internalPointer())->columnCount();
            else
                return rootItem->columnCount();
        }

        QVariant TreeModel::data(const QModelIndex &index, int role) const
        {
            if (!index.isValid())
                return QVariant();

            if (role != Qt::DisplayRole)
                return QVariant();

            TreeItem *item = static_cast<TreeItem*>(index.internalPointer());

            return item->data(index.column());
        }

        Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
        {
            if (!index.isValid())
                return Qt::ItemIsEnabled;

            return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
        }

        QVariant TreeModel::headerData(int section, Qt::Orientation orientation,
                                       int role) const
        {
            if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
                return rootItem->data(section);

            return QVariant();
        }

        QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent)
                    const
        {
            TreeItem *parentItem;

            if (!parent.isValid())
                parentItem = rootItem;
            else
                parentItem = static_cast<TreeItem*>(parent.internalPointer());

            TreeItem *childItem = parentItem->child(row);
            if (childItem)
                return createIndex(row, column, childItem);
            else
                return QModelIndex();
        }

        QModelIndex TreeModel::parent(const QModelIndex &index) const
        {
            if (!index.isValid())
                return QModelIndex();

            TreeItem *childItem = static_cast<TreeItem*>(index.internalPointer());
            TreeItem *parentItem = childItem->parent();

            if (parentItem == rootItem)
                return QModelIndex();

            return createIndex(parentItem->row(), 0, parentItem);
        }

        int TreeModel::rowCount(const QModelIndex &parent) const
        {
            TreeItem *parentItem;

            if (!parent.isValid())
                parentItem = rootItem;
            else
                parentItem = static_cast<TreeItem*>(parent.internalPointer());

            return parentItem->childCount();
        }

        void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
        {
            QList<TreeItem*> parents;
            QList<int> indentations;
            parents << parent;
            indentations << 0;

            int number = 0;

            while (number < lines.count()) {
                int position = 0;
                while (position < lines[number].length()) {
                    if (lines[number].mid(position, 1) != " ")
                        break;
                    position++;
                }

                QString lineData = lines[number].mid(position).trimmed();

                if (!lineData.isEmpty()) {
                    // Read the column data from the rest of the line.
                    QStringList columnStrings = lineData.split("\t", QString::SkipEmptyParts);
                    QList<QVariant> columnData;
                    for (int column = 0; column < columnStrings.count(); ++column)
                        columnData << columnStrings[column];

                    if (position > indentations.last()) {
                        // The last child of the current parent is now the new parent
                        // unless the current parent has no children.

                        if (parents.last()->childCount() > 0) {
                            parents << parents.last()->child(parents.last()->childCount()-1);
                            indentations << position;
                        }
                    } else {
                        while (position < indentations.last() && parents.count() > 0) {
                            parents.pop_back();
                            indentations.pop_back();
                        }
                    }

                    // Append a new item to the current parent's list of children.
                    parents.last()->appendChild(new TreeItem(columnData, parents.last()));
                }

                number++;
            }
        }