Qt實現鼠標拖動窗口

QPoint m_StartPoint; //鼠標按下起點
bool m_bMousePress; //按下鼠標左鍵

void CMyUpdateDlg::mouseMoveEvent(QMouseEvent *event)
{
    //移動窗口
    if (m_bMousePress)
    {
        QPoint curPoint = event->globalPos();   //按住移動時的位置
        QPoint movePoint = curPoint - m_StartPoint;

　　　　　//普通窗口
        QPoint mainWinPos = this->pos();

        this->move(mainWinPos.x() + movePoint.x(), mainWinPos.y() + movePoint.y());

　　　　　//標題欄
　　　　　QPoint mainWinPos = QPoint(parentWidget()->x(), parentWidget()->y());
　　　　　QPoint pos = mainWinPos + movePoint;
　　　　　parentWidget()->move(pos);

        m_StartPoint = curPoint;
    }
}

void CMyUpdateDlg::mousePressEvent(QMouseEvent * event)
{
    //只能是鼠標左鍵移動和改變大小
    if (event->button() == Qt::LeftButton)
    {
        m_bMousePress = true;
    }

    //按下時鼠標左鍵時，窗口在屏幕中的坐標
    m_StartPoint = event->globalPos();
}

void CMyUpdateDlg::mouseReleaseEvent(QMouseEvent * event)
{
    m_bMousePress = false;
}