图像处理细胞识别程序增加矩形框办法

大家可以参考我的框架程序，完成后续教程编成，思考if (m_bDrag)中能否将m_bDrag换成m_bClickEmpty？

1.将下面代码添加到学号view.h文件中

    bool m_bClickEmpty; //判断是否点击了空白的地方，以实现拖动框选择
    CPoint OldEmptyBegin;//点击空白开始的座标
    CPoint NowEmptyEnd;//移动时保存座标

2.将下面添加到学号view.cpp文件中void CCellPrg226View::OnMouseMove(UINT nFlags, CPoint point)函数里面（270行)

if (m_bDrag)//思考能否将m_bDrag换成m_bClickEmpty
    {
        CClientDC dc(this);

        CBrush* pBrush = CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));

        CBrush* POldBrush = dc.SelectObject(pBrush);

        int nOldMode = dc.SetROP2(R2_NOTXORPEN);

        dc.Rectangle(&CRect(OldEmptyBegin, NowEmptyEnd));

        dc.Rectangle(&CRect(OldEmptyBegin, point));

        NowEmptyEnd = point;

        dc.SelectObject(POldBrush);

        dc.SetROP2(nOldMode);

    }

3.将下面添加到学号view.cpp文件中void CCellPrg226View::OnLButtonDown(UINT nFlags, CPoint point)函数里面

    m_bClickEmpty = true;
    OldEmptyBegin = point;
    NowEmptyEnd = point;

效果