QGraphicsView::fitInView moves small item far away from the viewport.

void test(){
    auto win = new QMainWindow;
    auto scene = new QGraphicsScene(win);
    scene->setSceneRect(QRectF(0, 0, 5000, 5000));
    auto view = new QGraphicsView(scene);
    auto fitBtn = new QPushButton("FitInViewBtn");
    auto layout = new QVBoxLayout;
    layout->addWidget(fitBtn);
    layout->addWidget(view);
    QWidget *widget = new QWidget;
    widget->setLayout(layout);
    win->setCentralWidget(widget);
    win->setGeometry(100, 100, 800, 600);
    win->show();    
    auto textItem = new QGraphicsTextItem("TestTextItem");
    textItem->setFlag(QGraphicsItem::ItemIsMovable);
    textItem->setFlag(QGraphicsItem::ItemIsSelectable);
    textItem->setPos(view->mapToScene(view->viewport()->rect().center()));
    scene->addItem(textItem);    

    // scale number to chang item view size,bigger number greater than 1E106 will move item far away from view port
    double scale = 1.0E7; 
    fitBtn->connect(fitBtn,&QPushButton::clicked,[=](){
        auto extent = textItem->sceneBoundingRect();
        qDebug() << "before>> extent:" << extent << ",extentCenter:" << extent.center() << ",viewRect:" << view->viewport()->rect()
                 << ",viewSceneCenter:" << view->mapToScene(view->viewport()->rect().center())
                 << ",view.m11:" << view->transform().m11() << ",item.m11:" << textItem->transform().m11();        textItem->setScale(1/scale);
        
        textItem->setScale(1/scale);
        extent = textItem->sceneBoundingRect();

        view->fitInView(extent,Qt::KeepAspectRatio);   
     
        qDebug() << "after>> extent:" << extent << ",extentCenter:" << extent.center() << ",viewRect:" << view->viewport()->rect()
                 << ",viewSceneCenter:" << view->mapToScene(view->viewport()->rect().center())
                 << ",view.m11:" << view->transform().m11() << ",item.m11:" << textItem->transform().m11();
    });
}
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    test();
    return a.exec();
}