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

     /****************************************************************************
     **
     ** Copyright (C) 2004-2006 Trolltech ASA. All rights reserved.
     **
     ** This file is part of the demonstration applications of the Qt Toolkit.
     **
     ** This file may be used under the terms of the GNU General Public
     ** License version 2.0 as published by the Free Software Foundation
     ** and appearing in the file LICENSE.GPL included in the packaging of
     ** this file.  Please review the following information to ensure GNU
     ** General Public Licensing requirements will be met:
     ** http://www.trolltech.com/products/qt/opensource.html
     **
     ** If you are unsure which license is appropriate for your use, please
     ** review the following information:
     ** http://www.trolltech.com/products/qt/licensing.html or contact the
     ** sales department at sales@trolltech.com.
     **
     ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
     ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
     **
     ****************************************************************************/

     #include "model.h"
     #include <QIcon>
     #include <QPixmap>

     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);
     }