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 }