source: trunk/doc/src/snippets/persistentindexes/model.cpp@ 846

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/*
  model.cpp

  A simple model that uses a QStringList as its data source.
*/

#include <qdebug.h>

#include "model.h"

/*!
    Returns the number of items in the string list as the number of rows
    in the model.
*/

int StringListModel::rowCount(const QModelIndex &parent) const
{
    return stringList.count();
}

/*!
    Returns an appropriate value for the requested data.
    If the view requests an invalid index, an invalid variant is returned.
    If a header is requested then we just return the column or row number,
    depending on the orientation of the header.
    Any valid index that corresponds to a string in the list causes that
    string to be returned.
*/

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

    if (index.row() < 0 || index.row() >= stringList.size())
        return QVariant();

    if (role == Qt::DisplayRole)
        return stringList.at(index.row());
    else
        return QVariant();
}

/*!
    Returns the appropriate header string depending on the orientation of
    the header and the section. If anything other than the display role is
    requested, we return an invalid variant.
*/

QVariant StringListModel::headerData(int section, Qt::Orientation orientation,
                                     int role) const
{
    if (role != Qt::DisplayRole)
        return QVariant();

    if (orientation == Qt::Horizontal)
        return QString("Column %1").arg(section);
    else
        return QString("Row %1").arg(section);
}

/*!
    Returns an appropriate value for the item's flags. Valid items are
    enabled, selectable, and editable.
*/

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

    return QAbstractItemModel::flags(index) | Qt::ItemIsEditable;
}

/*!
    Changes an item in the string list, but only if the following conditions
    are met:

    * The index supplied is valid.
    * The index corresponds to an item to be shown in a view.
    * The role associated with editing text is specified.

    The dataChanged() signal is emitted if the item is changed.
*/

bool StringListModel::setData(const QModelIndex &index,
                              const QVariant &value, int role)
{
    if (index.isValid() && role == Qt::EditRole) {

        stringList.replace(index.row(), value.toString());
        emit dataChanged(index, index);
        return true;
    }
    return false;
}

/*!
    Inserts a number of rows into the model at the specified position.
*/

bool StringListModel::insertRows(int position, int rows, const QModelIndex &parent)
{
    beginInsertRows(parent, position, position + rows - 1);

    for (int row = 0; row < rows; ++row) {
        stringList.insert(position, "");
    }

    endInsertRows();
    return true;
}

/*!
    Removes a number of rows from the model at the specified position.
*/

bool StringListModel::removeRows(int position, int rows, const QModelIndex &parent)
{
    beginRemoveRows(parent, position, position + rows - 1);

    for (int row = 0; row < rows; ++row) {
        stringList.removeAt(position);
    }

    endRemoveRows();
    return true;
}