How to make rectangle selection on QgsMapCanvas?

I have this code for create and open raster map:

if(QFile::exists(rasterFileName))
{
    QFileInfo myRasterFileInfo(rasterFileName);
    m_pRasterLayer = QSharedPointer<QgsRasterLayer>(
        new QgsRasterLayer(myRasterFileInfo.filePath(), 
        myRasterFileInfo.completeBaseName()));

    if (m_pRasterLayer->isValid())
    {
        QgsMapLayerRegistry::instance()->addMapLayer(
            m_pRasterLayer.data(), true);

        QList<QgsMapCanvasLayer> layerList;
        layerList.append(QgsMapCanvasLayer(m_pRasterLayer.data(), true));

        m_pMapCanvas->setLayerSet(layerList);

        /* ... */
    }
}

How can I make (write code for) rectangle selection by mouse on my map?