【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。

    CDC *pDC0 = GetDlgItem(IDC_VIDEO0)->GetDC();
    CFont font;                                               // GDI对象
    font.CreatePointFont(200, _T("宋体"));                    //CreateXXX
    CFont *oldFont = pDC0->SelectObject(&font);
    pDC0->TextOut(20, 20, CString(_T("1")));
    pDC0->SelectObject(oldFont);

    GetDlgItem(IDC_VIDEO0)->ReleaseDC(pDC0); 

   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

    CRect rect;
    CDC* pDC = GetDlgItem(m_nCurrentPicture)->GetDC();
    GetDlgItem(m_nCurrentPicture)->GetClientRect(&rect);

    CPen pen(PS_SOLID, 10, RGB(0x99, 0x32, 0xcc));
    CPen *oldPen = NULL;
    oldPen = pDC->SelectObject(&pen);

    //上边框;
    pDC->MoveTo(rect.TopLeft());
    pDC->LineTo(CPoint(rect.TopLeft().x + rect.Width(),   //x
        rect.TopLeft().y                                          //y
        ) );

    //右边框;
    pDC->MoveTo(CPoint(rect.TopLeft().x + rect.Width(),   //x
        rect.TopLeft().y                                  //y
        ));
    pDC->LineTo(rect.BottomRight());

    //下边框;
    pDC->MoveTo(rect.BottomRight());
    pDC->LineTo(rect.TopLeft().x,                         //x
        rect.BottomRight().y                              //y
        );

    //左边框;
    pDC->MoveTo(rect.TopLeft().x,                         //x
        rect.BottomRight().y                              //y
        );
    pDC->LineTo(rect.TopLeft());


    pDC->SelectObject(oldPen);

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

void CCameraMonitorView::OnDraw(CDC* /*pDC*/)
{
    // TODO: 在此添加专用代码和/或调用基类;

    if (0 != m_nCurrentPicture)
    {
        ChoosePicture(m_nCurrentPicture);
    } 

    int index = 0;
    for (index = 0; index < MAX_CAMERAS_NUM; ++ index)
    {
        if (videoPicturesCtrl[index] != 0)
        {
            CDC *pDC = GetDlgItem(videoPicturesCtrl[index])->GetDC();
            CFont font;
            font.CreatePointFont(800, _T("宋体"));
            CFont *oldFont = pDC->SelectObject(&font);
            pDC->SetBkMode(TRANSPARENT);
            CRect rect;
            GetDlgItem(videoPicturesCtrl[index])->GetClientRect(&rect);

            int x = (rect.Width() / 2) - 20;
            int y = (rect.Height() / 2) - 40;
            char numArr[5] = {0};
            _itoa_s(index + 1, numArr, RADIX_10);
            CString strDisplayNum(numArr);

            pDC->TextOut(x, y, strDisplayNum);
            pDC->SelectObject(oldFont); 

            GetDlgItem(IDC_VIDEO1)->ReleaseDC(pDC);

            font.DeleteObject(); 
            
        }
    }
 
}

 

 

 

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

bool DrawPicToHDC(IplImage *img, HWND hWnd, bool bIsShowInfo)
{ 
    CWnd *pWnd = CWnd::FromHandle(hWnd);
    if (NULL == pWnd || FALSE == ::IsWindow(pWnd->m_hWnd))
    {
        AfxMessageBox(_T("DrawPicToHDC error 2"));
        return false;
    } 

    CDC *pDC = pWnd->GetDC();
    HDC hDC = pDC->GetSafeHdc();
    CRect rect;
    pWnd->GetClientRect(&rect);
    CvvImage cimg;
    cimg.CopyOf(img);
    cimg.DrawToHDC(hDC, &rect); 

    pDC->SetBkMode(TRANSPARENT);              //文字透明;
    CTime time = CTime::GetCurrentTime();     //获得当前时间;
    CString strTime;
    strTime = time.Format("%Y-%m-%d  %H:%M:%S");
 
    CFont font;
    font.CreatePointFont(200, _T("宋体"), NULL);
    CFont *oldFont = pDC->SelectObject(&font);
    pDC->SetTextColor(RGB(255, 0, 0));       //文字颜色

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

    if (true == bIsShowInfo)
    {
        pDC->TextOut(10, 35, CString("正在录像..."));
    }

    pDC->SelectObject(oldFont);

    ReleaseDC(hWnd,hDC);   //释放DC
    font.DeleteObject();     //释放GDI对象

    return true;    
}