Перетаскивание карты мышью

MainWindow::MainWindow()
{
    viewMap = new QDMapView();

    //...
    // Остальной код
    //...

    connect(viewMap, SIGNAL(SignalMousePress(int,int,int)), this, SLOT(mapMousePress(int,int,int)));
    connect(viewMap, SIGNAL(SignalMouseRelease(int,int,int)), this, SLOT(mapMouseRelease(int,int,int)));
}


void MainWindow::mapMousePress(int x, int y, int mod)
{
    // Getting top left point from map
    int mapx,mapy;
    viewMap->GetMapLeftTop(&mapx,&mapy);

    // Getting reference point from widget
    QPoint pmap = viewMap->mapFromGlobal(QCursor::pos());

    setCursor(Qt::ClosedHandCursor);

    // Draging map
    mousePressed = true;
    while (mousePressed)
    {
        // Getting new point
        pmap = viewMap->mapFromGlobal(QCursor::pos());

        // Calculating offset
        int dx = pmap.x() - x;
        int dy = pmap.y() - y;

        // Offset for the point
        x = x + dx;
        y = y + dy;

        // Offset for the map
        mapx = mapx - dx;
        mapy = mapy - dy;

        // Setting new point for map
        viewMap->SetMapLeftTop(mapx,mapy);
    }

}
void MainWindow::mapMouseRelease(int x, int y, int mod)
{
    mousePressed = false;
    setCursor(Qt::ArrowCursor);
}