鼠标事件，为啥不用调用基类的实现

鼠标事件，为何不用调用基类的实现？
QWidget::mousePressEvent(event)加多一行也是可以的。

有的重载函数要调用基类的实现，有的不用。这到底从哪判定的？

如果是MFC，一般它会自动生成代码，把架构搭好了。现在Qt简洁了，自行添加。

C/C++ code

void editPainter::mousePressEvent(QMouseEvent *event){    Q_UNUSED(event);    m_bMousePressed = true;}void editPainter::mouseMoveEvent(QMouseEvent *event){    QPoint pt = event->pos();    if (!m_bDisChangeDir)    {        //根据鼠标位置，调整方向（鼠标释放状态下，此可不断变化）        if (m_rcTopLeft.contains(pt))        {            setCursor(Qt::SizeFDiagCursor);            m_enAction = DRAG_TOP_LEFT;        }        else if (m_rcTopRight.contains(pt))        {            setCursor(Qt::SizeBDiagCursor);            m_enAction = DRAG_TOP_RIGHT;        }        else if (m_rcBottomLeft.contains(pt))        {            setCursor(Qt::SizeBDiagCursor);            m_enAction = DRAG_BOTTOM_LEFT;        }        else if (m_rcBottomRight.contains(pt))        {            setCursor(Qt::SizeFDiagCursor);            m_enAction = DRAG_BOTTOM_RIGHT;        }        else if (m_rcLeftMiddle.contains(pt))        {            setCursor(Qt::SizeHorCursor);            m_enAction = DRAG_LEFTMIDDLE;        }        else if (m_rcRightMiddle.contains(pt))        {            setCursor(Qt::SizeHorCursor);            m_enAction = DRAG_RIGHTMIDDLE;        }        else if (m_rcTopMiddle.contains(pt))        {            setCursor(Qt::SizeVerCursor);            m_enAction = DRAG_TOPMIDDLE;        }        else if (m_rcBottomMiddle.contains(pt))        {            setCursor(Qt::SizeVerCursor);            m_enAction = DRAG_BOTTOMMIDDLE;        }        else if (m_rectOfRedLine.contains(pt))        {            setCursor(Qt::SizeAllCursor);            m_enAction = DRAG_CENTER;        }        else        {            setCursor(Qt::ArrowCursor);            m_enAction = NO_ACTION;        }        //鼠标按下后，方向确认，且不更改了        if (m_bMousePressed)        {            m_bDisChangeDir = true;        }    }    calculatePaintRect(event, m_enAction);    m_ptLast = event->pos();}void editPainter::mouseReleaseEvent(QMouseEvent *event){    Q_UNUSED(event);    m_bMousePressed = false;    m_bDisChangeDir = false;}