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# model.cpp Example File
demos/interview/model.cpp

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        **
        ** Copyright (C) 1992-2005 Trolltech AS. All rights reserved.
        **
        ** 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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        #include "model.h"
        #include <qicon.h>
        #include <qpixmap.h>

        Model::Model(int rows, int columns, QObject *parent)
            : QAbstractItemModel(parent),
              rc(rows), cc(columns),
              tree(new QVector<Node>(rows, Node(0)))
        {

        }

        Model::~Model()
        {
            delete tree;
        }

        QModelIndex Model::index(int row, int column, const QModelIndex &parent) const
        {
            if (row < rc && row >= 0 && column < cc && column >= 0) {
                Node *p = static_cast<Node*>(parent.internalPointer());
                Node *n = node(row, p);
                if (n)
                    return createIndex(row, column, n);
            }
            return QModelIndex();
        }

        QModelIndex Model::parent(const QModelIndex &child) const
        {
            if (child.isValid()) {
                Node *n = static_cast<Node*>(child.internalPointer());
                Node *p = parent(n);
                if (p)
                    return createIndex(row(p), 0, p);
            }
            return QModelIndex();
        }

        int Model::rowCount(const QModelIndex &parent) const
        {
            Q_UNUSED(parent);
            return rc;
        }

        int Model::columnCount(const QModelIndex &parent) const
        {
            Q_UNUSED(parent);
            return cc;
        }

        QVariant Model::data(const QModelIndex &index, int role) const
        {
            static QIcon folder(QPixmap(":/images/folder.png"));

            if (role == Qt::DisplayRole)
                return "Item " + QString::number(index.row()) + ":" + QString::number(index.column());
            if (role == Qt::DecorationRole)
                return qVariantFromValue(folder);
            return QVariant();
        }

        QVariant Model::headerData(int section, Qt::Orientation orientation, int role) const
        {
            static QIcon services(QPixmap(":/images/services.png"));
            if (role == Qt::DisplayRole)
                return QString::number(section);
            if (role == Qt::DecorationRole)
                return qVariantFromValue(services);
            return QAbstractItemModel::headerData(section, orientation, role);
        }

        bool Model::hasChildren(const QModelIndex &parent) const
        {
            Q_UNUSED(parent);
            return rc > 0 && cc > 0;
        }

        Qt::ItemFlags Model::flags(const QModelIndex &) const
        {
            return (Qt::ItemIsDragEnabled|Qt::ItemIsSelectable|Qt::ItemIsEnabled);
        }

        Model::Node *Model::node(int row, Node *parent) const
        {
            if (parent && !parent->children)
                parent->children = new QVector<Node>(rc, Node(parent));
            QVector<Node> *v = parent ? parent->children : tree;
            return const_cast<Node*>(&(v->at(row)));
        }

        Model::Node *Model::parent(Node *child) const
        {
            return child ? child->parent : 0;
        }

        int Model::row(Node *node) const
        {
             const Node *first = node->parent ? &(node->parent->children->at(0)) : &(tree->at(0));
             return (node - first);
        }