Qt QGraphicsItem 移动时出现残影问题记录

QRectF CGraphicsDragItem::boundingRect() const
{
    return QRectF(
        -m_penWidth/2,
        -m_penWidth/2,
        m_rectWidth+m_penWidth,
        m_rectHeight+m_penWidth);
}
void CGraphicsDragItem::paint(
    QPainter *painter,
    const QStyleOptionGraphicsItem *option,
    QWidget *widget)
{
    Q_UNUSED(option);
    Q_UNUSED(widget);
    if (hasFocus() || !collidingItems().isEmpty())
    {
        m_penWidth = 10;
        painter->setPen(QPen(QColor(255, 255, 255, 200), m_penWidth));
        if (hasFocus())
        {
            for (auto it : collidingItems())
            {
                it->update();
            }
        }
    }
    else
    {
        m_penWidth = 1;
        painter->setPen(QPen(QColor(100, 100, 100, 100), m_penWidth));
    }
    painter->setBrush(m_clrBrush);
    painter->drawEllipse(0, 0, m_rectWidth, m_rectHeight);
}