MFC画图实现实时显示图形轨迹

最新推荐文章于 2025-06-10 13:59:14 发布

原创最新推荐文章于 2025-06-10 13:59:14 发布 · 6.6k 阅读

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（1 ）在类里定义变量和消息:

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

afx_msg void OnMouseMove(UINT nFlags, CPoint point);afx_msg void OnLButtonDown(UINT nFlags, CPoint point);afx_msg void OnLButtonUp(UINT nFlags, CPoint point);

( 2 )在鼠标相关的消息里面写代码:

void XX::OnLButtonDown(UINT nFlags, CPoint point){

       m_bClickEmpty = true;

      OldEmptyBegin = point;

       NowEmptyEnd = point;

}

void XX::OnMouseMove(UINT nFlags, CPoint point)

{

     if ( 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 );

    }

}

void XX::OnLButtonUp(UINT nFlags, CPoint point){

      if ( m_bClickEmpty )      {           m_bClickEmpty = false;

           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.SelectObject( POldBrush );

         dc.SetROP2( nOldMode );

      }}