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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.
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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++;
        }
    }