MFC画线

最新推荐文章于 2023-09-27 18:20:48 发布

lieyingshengbao

最新推荐文章于 2023-09-27 18:20:48 发布

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MFC画线：
1、画线：
   1）DrawView.h中：
      定义CPoint m_ptOrign;
      DrawView.cpp中：

在DrawView的OnLButtonDown消息中， //鼠标按下消息
保存鼠标左键按下的point。 m_ptOrign = point;

      在DrawView的OnLButtonUp消息中，        //鼠标弹起消息
    i）
      SDK模式:
      HDC hDC;
      hDC = ::GetDC(m_hWnd);                  //此处要用全局的::GetDC,否则默认用CDC的。
      MoveToEx(hDC, m_ptOrign.x, m_ptOrign.y, NULL); //MoveToEx。先移到初始点，然后再画线
      LineTo(hDC, point.x, point.y);
      ::ReleaseDC(m_hWnd, hDC);               //释放也要用全局::ReleaseDC。

      MFC模式：(包含画笔)
      CDC *pDC = GetDC();
      CPen pen(PS_SOLID, 5, RGB(255,0,0));
      CPen *pOldPen = pDC->SelectObject(&pen); //将pen选入设备描述表
      pDC->MoveTo(m_ptOrign);
      pDC->LineTo(point);
      pDC->SelectObject(pOldPen);               //返还旧画笔
      ReleaseDC(pDC);

      CClientDC dc(GetParent());   //CClientDC,继承自CDC,不需要手动GetDC和ReleaseDC,传递this或GetParent()
      CPen pen(PS_SOLID, 5, RGB(255,0,0));
      CPen *pOldPen = dc.SelectObject(&pen);
      dc.MoveTo(m_ptOrign);
      dc.LineTo(point);
      dc.SelectObject(pOldPen);

      CWindowDC dc(GetDesktopWindow()); //CWindowDC继承自CDC，包含客户区和非客户区。GetDesktopWindow()获取桌面
      CPen pen(PS_SOLID, 5, RGB(255,0,0));
      CPen *pOldPen = dc.SelectObject(&pen);
      dc.MoveTo(m_ptOrign);
      dc.LineTo(point);
      dc.SelectObject(pOldPen);

      画刷：
      CBrush brush(RGB(255,0,0));
      CClientDC dc(this);                 //CClientDC传递this
      dc.FillRect(CRect(m_ptOrign, point), &brush);      //FillRect填充

      透明画刷：
      CClientDC dc(this);
      CBrush *pBrush = CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH)); //创建透明画刷
      CBrush *pOld = dc.SelectObject(pBrush);
      dc.Rectangle(CRect(m_ptOrign, point));     //画矩形
      dc.SelectObject(pOld);                     //最后返还画刷

2. 实现画笔功能，连续画线
   1）在DrawView.h中，添加BOOL m_bDraw;
   2）在DrawView.cpp中，
      OnLButtonDown消息中：m_bDraw = TRUE；
      OnLButtonUp消息中：m_bDraw = FALSE;
      OnMouseMove消息中：
        CClientDC dc(this);
CPen pen(PS_SOLID, 5, RGB(255,0,0));
CPen *pOldPen = dc.SelectObject(&pen);
if (m_bDraw)
{
  dc.MoveTo(m_ptOrign);
  dc.LineTo(point);
  m_ptOrign = point;       //移动点坐标。必需的
}
dc.SelectObject(pOldPen);        //返还画笔