qt 鼠标拖动窗口放大缩小

// 鼠标拖动 具体实现
void mouseMoveEvent(QMouseEvent * pEvent)
{    
    if (pEvent->buttons() & Qt::LeftButton)
    {
        if (resizeDir == nodir)
        {//移动窗口
            QPoint newPos = pEvent->globalPos();

            move(newPos - m_PressedPos);

            emit signal_drawWidgetPositionChange(this->pos().x(), this->pos().y());
        }
        else
        {
            //ptop,pbottom,pleft,pright;                   //窗口上下左右的值
            int ptop = frameGeometry().top();
            int pbottom = frameGeometry().bottom();
            int pleft = frameGeometry().left();
            int pright = frameGeometry().right();
            if(resizeDir & top)
            {
                //检测更改尺寸方向中包含的上下左右分量
                if(height() == minimumHeight())
                {
                    ptop = min(pEvent->globalY(),ptop);
                }
                else if(height() == maximumHeight())
                {
                    ptop = max(pEvent->globalY(),ptop);
                }
                else
                {
                    ptop = pEvent->globalY();
                }
            }
            else if(resizeDir & bottom)
            {
                if(height() == minimumHeight())
                {
                    pbottom = max(pEvent->globalY(),ptop);
                }
                else if(height() == maximumHeight())
                {
                    pbottom = min(pEvent->globalY(),ptop);
                }
                else
                {
                    pbottom = pEvent->globalY();
                }
            }

            if(resizeDir & left)
            {                        //检测左右分量
                if(width() == minimumWidth())
                {
                    pleft = min(pEvent->globalX(),pleft);
                }
                else if(width() == maximumWidth())
                {
                    pleft = max(pEvent->globalX(),pleft);
                }
                else
                {
                    pleft = pEvent->globalX();
                }
            }
            else if(resizeDir & right)
            {
                if(width() == minimumWidth())
                {
                    pright = max(pEvent->globalX(),pright);
                }
                else if(width() == maximumWidth())
                {
                    pright = min(pEvent->globalX(),pright);
                }
                else
                {
                    pright = pEvent->globalX();
                }
            }
            //setGeometry(QRect(QPoint(pleft,ptop),QPoint(pright, pbottom)));

            // 限制大小

            if (m_iMaxWindowWidth <= pright - pleft)
            {
                if (m_iMaxWindowHeight <= pbottom - ptop)
                {
                    setGeometry(QRect(QPoint(pleft,ptop),QPoint(pleft + m_iMaxWindowWidth, ptop + m_iMaxWindowHeight)));
                }else
                {
                    setGeometry(QRect(QPoint(pleft,ptop),QPoint(pleft + m_iMaxWindowWidth, pbottom)));
                }
            }else
            {
                if (m_iMaxWindowHeight <= pbottom - ptop)
                {
                    setGeometry(QRect(QPoint(pleft,ptop),QPoint(pright, ptop + m_iMaxWindowHeight)));
                }else
                {
                    setGeometry(QRect(QPoint(pleft,ptop),QPoint(pright, pbottom)));
                }
            }
        }
    }
    else
    {
        findWidgetEdge();
    }//当不拖动窗口、不改变窗口大小尺寸的时候  检测鼠标边缘
}

// 计算窗口边缘

void findWidgetEdge()
{
    int diffLeft = abs(cursor().pos().x() - frameGeometry().left());      //计算鼠标距离窗口上下左右有多少距离
    int diffRight = abs(cursor().pos().x() - frameGeometry().right());
    int diffTop = abs(cursor().pos().y() - frameGeometry().top());
    int diffBottom = abs(cursor().pos().y() - frameGeometry().bottom());

    QCursor tempCursor;                                    //获得当前鼠标样式
    tempCursor = cursor();

    if(diffTop < m_iEdgeMargin)
    {
        //根据 边缘距离 分类改变尺寸的方向
        if(diffLeft < m_iEdgeMargin)
        {
            resizeDir = topLeft;
            tempCursor.setShape(Qt::SizeFDiagCursor);
        }
        else if(diffRight < m_iEdgeMargin)
        {
            resizeDir = topRight;
            tempCursor.setShape(Qt::SizeBDiagCursor);
        }
        else
        {
            resizeDir = top;
            tempCursor.setShape(Qt::SizeVerCursor);
        }
    }
    else if(diffBottom < m_iEdgeMargin)
    {
        if(diffLeft < m_iEdgeMargin)
        {
            resizeDir = bottomLeft;
            tempCursor.setShape(Qt::SizeBDiagCursor);
        }
        else if(diffRight < m_iEdgeMargin)
        {
            resizeDir = bottomRight;
            tempCursor.setShape(Qt::SizeFDiagCursor);
        }
        else
        {
            resizeDir = bottom;
            tempCursor.setShape(Qt::SizeVerCursor);
        }
    }
    else if(diffLeft < m_iEdgeMargin)
    {
        resizeDir = left;
        tempCursor.setShape(Qt::SizeHorCursor);
    }
    else if(diffRight < m_iEdgeMargin)
    {
        resizeDir = right;
        tempCursor.setShape(Qt::SizeHorCursor);
    }
    else
    {
        resizeDir = nodir;
        tempCursor.setShape(Qt::ArrowCursor);
    }

    setCursor(tempCursor);                    //重新设置鼠标,主要是改样式
}

void mouseReleaseEvent(QMouseEvent *)
{
    if(resizeDir != nodir)
    {         //还原鼠标样式
        findWidgetEdge();
    }
//    this->setCursor(Qt::ArrowCursor);
}

void mousePressEvent(QMouseEvent * pEvent)
{
    if (Qt::LeftButton == pEvent->button())
    {
        this->setCursor(Qt::PointingHandCursor);
        m_PressedPos = pEvent->globalPos() - this->pos();
        m_dragPosition = pEvent->globalPos() - frameGeometry().topLeft();  //获得鼠标按键位置相对窗口左上面的位置
    }
}