自定义QGraphicsItemGroup：未正确绘制boundingRect

Question

我有一个自定义QGraphicsItemGroup，带有一组固定的子项。我需要使它可以调整大小（已经完成），但是，在调整大小时，boundingRect不会更新 - 但是，所有子项都是正确绘制的。我已经尝试在程序的不同位置添加prepareGeometryChange（）和update（），但这没有帮助。

即使这个实现返回默认的boundingRect：

QRectF FigureGraphicsItemGroup::boundingRect() const
{
    return childrenBoundingRect().adjusted(0, 0, 50, 0);
}

和一些必要的代码（NB没有自定义绘画）：

m_right：正确控制调整大小。

QRectF FigureGraphicsItemGroup::boundingRect() const
{
    return childrenBoundingRect();
}

void FigureGraphicsItemGroup::mousePressEvent(QGraphicsSceneMouseEvent* event)
{
    QPointF pos = event->pos();

    if (m_right->contains(pos) && m_right->isVisible())
    {
        m_isResized = true;
    }
    else
        QGraphicsItemGroup::mousePressEvent(event);
}

void FigureGraphicsItemGroup::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
    QPointF pos = event->pos();

    if (m_isResized)
    {
        if (m_previous.x() == -1 && m_previous.y() == -1)
            m_previous = pos;

        m_delta = pos.x() - m_previous.x();
        m_previous = pos;

        QGraphicsItem::prepareGeometryChange();
        recalculatePositions();
    }
    else
    {
        QGraphicsItemGroup::mouseMoveEvent(event);
    }
}

void FigureGraphicsItemGroup::hoverMoveEvent(QGraphicsSceneHoverEvent *event)
{
    QPointF pos = event->pos();

    if (m_right->contains(pos) && m_right->isVisible())
    {
        setCursor(Qt::SizeHorCursor);
    }
    else
    {
        setCursor(Qt::ArrowCursor);
        QGraphicsItemGroup::hoverMoveEvent(event);
    }
}

void FigureGraphicsItemGroup::reset()
{
    m_isResized = false;
    m_delta = 0;
    m_previous = QPointF(-1 , -1);
}

void FigureGraphicsItemGroup::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
    Q_UNUSED(event)
    reset();

    QGraphicsItemGroup::mouseReleaseEvent(event);
}

QVariant FigureGraphicsItemGroup::itemChange(GraphicsItemChange change, const QVariant &value)
{
    switch (change)
    {
        case ItemSelectedHasChanged:
            m_isSelected = isSelected();
            m_right->setVisible(m_isSelected);
        break;
    }

    return QGraphicsItem::itemChange(change, value);
}

void FigureGraphicsItemGroup::recalculatePositions()
{
    int sumX = 1;

    QFontMetrics fm(m_zoneNumberSimpleTextItem->font());

    m_routeNumberSimpleTextItem->setPos(sumX, m_middle - fm.height());
    sumX += m_routeNumberSimpleTextItem->boundingRect().width() * SPACING;
//-------------------------------------------------------------------------------------------
    int diameter = fm.height() * SPACING;

    int pixLength = fm.width(m_zoneNumberSimpleTextItem->text());

    if (pixLength > diameter)
        diameter = pixLength;

    QPen pen(Qt::red);
    pen.setWidth(1);
    m_zoneCircleEllipseItem->setRect(sumX, m_middle - diameter, diameter, diameter);
    m_zoneCircleEllipseItem->setPen(pen);

    m_zoneNumberSimpleTextItem->setPos(sumX + fm.width(m_zoneNumberSimpleTextItem->text()) / 2,
                                       m_middle - fm.height());
    sumX += m_zoneCircleEllipseItem->boundingRect().width() * SPACING;
//-------------------------------------------------------------------------------------------
    m_fuelSimpleTextItem->setPos(sumX, m_middle * 1.1);
//-------------------------------------------------------------------------------------------
    m_leftCornerSvgItem->setPos(sumX, m_middle - m_leftCornerSvgItem->boundingRect().height() / 4);
    sumX += m_leftCornerSvgItem->boundingRect().width() * m_scale;
//-------------------------------------------------------------------------------------------
    pen.setColor(m_blue);
    pen.setWidth(4);
    m_leftLineItem->setPen(pen);
    int length = m_leftLineItem->line().length() + m_delta / 2;
    length = length < 0 ? 0 : length;
    m_leftLineItem->setLine(sumX, m_middle, sumX + length, m_middle);
    sumX += m_leftLineItem->boundingRect().width();
//-------------------------------------------------------------------------------------------
    m_exerciseSvgItem->setPos(sumX - 2, m_middle - m_exerciseSvgItem->boundingRect().height() / 4);
    sumX += m_exerciseSvgItem->boundingRect().width() * m_scale;
//-------------------------------------------------------------------------------------------
    pen.setColor(m_blue);
    pen.setWidth(4);
    m_rightLineItem->setPen(pen);
    length = m_rightLineItem->line().length() + m_delta / 2;
    length = length < 0 ? 0 : length;
    m_rightLineItem->setLine(sumX , m_middle, sumX + length, m_middle);
    sumX += m_rightLineItem->boundingRect().width();
//-------------------------------------------------------------------------------------------
    m_rightCornerSvgItem->setPos(sumX - 2, m_middle - m_rightCornerSvgItem->boundingRect().height() / 4);
    sumX += m_rightCornerSvgItem->boundingRect().width() * m_scale;
//-------------------------------------------------------------------------------------------
    m_right->setRect(sumX, m_middle, 4, 4);
//-------------------------------------------------------------------------------------------
}

UPD 一点点黑客帮助了我：只需添加removeFromGroup＆amp;调整大小期间某些项的addToGroup - 并且将正确绘制boundingRect。但它看起来有点奇怪。