qt - 为什么使用 fitInView() 函数时 QGraphicsPixmapItem 存在偏移量？

Question

我使用 fitInView() 函数查看图像像素，但是图像像素存在偏移，如何解决这个问题？

void QtGraphicsView::setViewRect(const QRectF &rect)
{
    if (m_viewRect == rect)
        return;

    m_viewRect = rect;
    fitInView(rect);
}

void QtGraphicsView::scaleView(qreal factor)
{
    const QSizeF &size = m_viewRect.size() / factor;
    if (size.width() <= 0 || size.height() <= 0
            || size.width() >= sceneRect().width()
            || size.height() >= sceneRect().height())
        return;

    const QSizeF &dsize = m_viewRect.size() - size;
    const QPointF &topLeft = m_viewRect.topLeft()
            + QPointF(dsize.width() / 2, dsize.height() / 2);
    setViewRect(QRectF(topLeft, size).toRect());
}