【2012年终总结】之二 opencv + ds采集摄像头视频 GDI点点滴滴

 

在这个项目中用到了几个GDI的函数，包括CFont  CPen  CBrush等，一般要和设备上下文DC结合起来使用。

并且创建GDI对象使用完后一定要释放，否则可能会造成资源泄漏

对于CPen CFont CBrush用构造函数定义的GDI对象 和 用 CreateXXX获得的对象在释放时要调用DeleteObject

对于GetXXX获得的对象在释放时要使用ReleaseObject。

 1     CDC *pDC0 = GetDlgItem(IDC_VIDEO0)->GetDC();

 2     CFont font;                                               // GDI对象

 3     font.CreatePointFont(200, _T("宋体"));                    //CreateXXX

 4     CFont *oldFont = pDC0->SelectObject(&font);

 5     pDC0->TextOut(20, 20, CString(_T("1")));

 6     pDC0->SelectObject(oldFont);

 7 

 8     GetDlgItem(IDC_VIDEO0)->ReleaseDC(pDC0); 

 9 

10    font.DeleteObject();                                  //释放GDI对象资源

 

下面的例子是画一个矩形的边框，矩形是一个Picture控件，当点击该控件时给这个控件的边缘画颜色

 1     CRect rect;

 2     CDC* pDC = GetDlgItem(m_nCurrentPicture)->GetDC();

 3     GetDlgItem(m_nCurrentPicture)->GetClientRect(&rect);

 4 

 5     CPen pen(PS_SOLID, 10, RGB(0x99, 0x32, 0xcc));

 6     CPen *oldPen = NULL;

 7     oldPen = pDC->SelectObject(&pen);

 8 

 9     //上边框;

10     pDC->MoveTo(rect.TopLeft());

11     pDC->LineTo(CPoint(rect.TopLeft().x + rect.Width(),   //x

12         rect.TopLeft().y                                          //y

13         ) );

14 

15     //右边框;

16     pDC->MoveTo(CPoint(rect.TopLeft().x + rect.Width(),   //x

17         rect.TopLeft().y                                  //y

18         ));

19     pDC->LineTo(rect.BottomRight());

20 

21     //下边框;

22     pDC->MoveTo(rect.BottomRight());

23     pDC->LineTo(rect.TopLeft().x,                         //x

24         rect.BottomRight().y                              //y

25         );

26 

27     //左边框;

28     pDC->MoveTo(rect.TopLeft().x,                         //x

29         rect.BottomRight().y                              //y

30         );

31     pDC->LineTo(rect.TopLeft());

32 

33 

34     pDC->SelectObject(oldPen);

35 

36     int ret = GetDlgItem(m_nCurrentPicture)->ReleaseDC(pDC); 

37     pDC = NULL; 

38     

39     pen.DeleteObject();

 

 多个Picture控件，每个Picture控件都在控件中间位置写上1 2 3 4等数字标识是哪个摄像头

 1 void CCameraMonitorView::OnDraw(CDC* /*pDC*/)

 2 {

 3     // TODO: 在此添加专用代码和/或调用基类;

 4 

 5     if (0 != m_nCurrentPicture)

 6     {

 7         ChoosePicture(m_nCurrentPicture);

 8     } 

 9 

10     int index = 0;

11     for (index = 0; index < MAX_CAMERAS_NUM; ++ index)

12     {

13         if (videoPicturesCtrl[index] != 0)

14         {

15             CDC *pDC = GetDlgItem(videoPicturesCtrl[index])->GetDC();

16             CFont font;

17             font.CreatePointFont(800, _T("宋体"));

18             CFont *oldFont = pDC->SelectObject(&font);

19             pDC->SetBkMode(TRANSPARENT);

20             CRect rect;

21             GetDlgItem(videoPicturesCtrl[index])->GetClientRect(&rect);

22 

23             int x = (rect.Width() / 2) - 20;

24             int y = (rect.Height() / 2) - 40;

25             char numArr[5] = {0};

26             _itoa_s(index + 1, numArr, RADIX_10);

27             CString strDisplayNum(numArr);

28 

29             pDC->TextOut(x, y, strDisplayNum);

30             pDC->SelectObject(oldFont); 

31 

32             GetDlgItem(IDC_VIDEO1)->ReleaseDC(pDC);

33 

34             font.DeleteObject(); 

35             

36         }

37     }

38  

39 }

 

 

 

从窗口指针获得DC

CDC *pDC = pWnd->GetDC();

 

 

根据DC获得HDC

HDC hDC = pDC->GetSafeHdc();

 

 

根据句柄获得窗口指针

CWnd *pWnd = FromHandle(hWnd);

 

void CJietu::OnPaint()

{

    CPaintDC dc(this); // device context for painting

    // TODO: 在此处添加消息处理程序代码

    // 不为绘图消息调用 CDialog::OnPaint()  

    

    HWND hWnd = m_hWnd;

    CWnd *pWnd = FromHandle(hWnd); 

    CDC *pDC = pWnd->GetDC();

    HDC hDC = pDC->GetSafeHdc();



    StretchBlt(hDC, 0, 0, m_nCx, m_nCy, m_hDCGlobal, 0, 0, m_nCx, m_nCy, SRCCOPY); 



    pWnd->ReleaseDC(pDC); 

     

}

 

 

 另外一个例子

 1 bool DrawPicToHDC(IplImage *img, HWND hWnd, bool bIsShowInfo)

 2 { 

 3     CWnd *pWnd = CWnd::FromHandle(hWnd);

 4     if (NULL == pWnd || FALSE == ::IsWindow(pWnd->m_hWnd))

 5     {

 6         AfxMessageBox(_T("DrawPicToHDC error 2"));

 7         return false;

 8     } 

 9 

10     CDC *pDC = pWnd->GetDC();

11     HDC hDC = pDC->GetSafeHdc();

12     CRect rect;

13     pWnd->GetClientRect(&rect);

14     CvvImage cimg;

15     cimg.CopyOf(img);

16     cimg.DrawToHDC(hDC, &rect); 

17 

18     pDC->SetBkMode(TRANSPARENT);              //文字透明;

19     CTime time = CTime::GetCurrentTime();     //获得当前时间;

20     CString strTime;

21     strTime = time.Format("%Y-%m-%d  %H:%M:%S");

22  

23     CFont font;

24     font.CreatePointFont(200, _T("宋体"), NULL);

25     CFont *oldFont = pDC->SelectObject(&font);

26     pDC->SetTextColor(RGB(255, 0, 0));       //文字颜色

27 

28     pDC->TextOut(10, 10, strTime);

29 

30     if (true == bIsShowInfo)

31     {

32         pDC->TextOut(10, 35, CString("正在录像..."));

33     }

34 

35     pDC->SelectObject(oldFont);

36 

37     ReleaseDC(hWnd,hDC);   //释放DC

38     font.DeleteObject();     //释放GDI对象

39 

40     return true;    

41 }