Display image in MFC / C ++ application using OpenCV

. StretchDIBits() BITMAPINFO, , StretchDIBits() , raw OpenCV Mat:: data 4 ! , , DC StretchDIBits(), , .

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void AdjustAspectImageSize( const Size& imageSize,
                            const Size& destSize, 
                                  Size& newSize )
{
   double destAspectRatio   =  float( destSize.width  )  /  float( destSize.height  );
   double imageAspectRatio  =  float( imageSize.width )  /  float( imageSize.height );

   if ( imageAspectRatio > destAspectRatio )
   {
      // Margins on top/bottom
      newSize.width    =   destSize.width;
      newSize.height   =   int( imageSize.height  *  
                                    ( double( destSize.width )  /  double( imageSize.width ) ) );
   }
   else
   {
      // Margins on left/right
      newSize.height   =   destSize.height;
      newSize.width    =   int( imageSize.width  *
                                    ( double( destSize.height )  /  double( imageSize.height ) ) );
   }
}


void DrawPicToHDC( Mat  cvImg, 
                   UINT nDlgID, 
                   bool bMaintainAspectRatio /* =true*/  )
{
   // Get the HDC handle information from the ID passed
   CDC* pDC  =  GetDlgItem(nDlgID)->GetDC();
   HDC  hDC  =  pDC->GetSafeHdc();

   CRect rect;
   GetDlgItem(nDlgID)->GetClientRect(rect);

   Size winSize( rect.right, rect.bottom );

   // Calculate the size of the image that
   // will fit in the control rectangle.
   Size origImageSize( cvImg.cols, cvImg.rows );
   Size imageSize;
   int  offsetX;
   int  offsetY;

   if ( ! bMaintainAspectRatio )
   {
      // Image should be the same size as the control rectangle
      imageSize = winSize;
   }
   else
   {
      Size newSize;

      _AdjustAspectImageSize( origImageSize,
                              winSize,
                              imageSize );
   }

   offsetX   =   ( winSize.width  - imageSize.width  )  /  2;
   offsetY   =   ( winSize.height - imageSize.height )  /  2;

   // Resize the source to the size of the destination image if necessary
   Mat cvImgTmp;

   resize( cvImg, 
           cvImgTmp, 
           imageSize,
           0,
           0,
           INTER_AREA );

   // To handle our Mat object of this width, the source rows must
   // be even multiples of a DWORD in length to be compatible with 
   // SetDIBits().  Calculate what the correct byte width of the 
   // row should be to be compatible with SetDIBits() below.
   int stride  =  ( ( ( ( imageSize.width * 24 )  +  31 )  &  ~31 )  >>  3 );

   // Allocate a buffer for our DIB bits
   uchar* pcDibBits  =  (uchar*) malloc( imageSize.height * stride );

   if ( pcDibBits != NULL )
   {
      // Copy the raw pixel data over to our dibBits buffer.
      // NOTE: Can setup cvImgTmp to add the padding to skip this.
      for ( int row = 0;  row < cvImgTmp.rows;  ++row )
      {
         // Get pointers to the beginning of the row on both buffers
         uchar* pcSrcPixel  =  cvImgTmp.ptr<uchar>(row);
         uchar* pcDstPixel  =  pcDibBits  +  ( row * stride );

         // We can just use memcpy
         memcpy( pcDstPixel,
                 pcSrcPixel,
                 stride );
      }

      // Initialize the BITMAPINFO structure
      BITMAPINFO bitInfo;

      bitInfo.bmiHeader.biBitCount       =  24;
      bitInfo.bmiHeader.biWidth          =   cvImgTmp.cols;
      bitInfo.bmiHeader.biHeight         =  -cvImgTmp.rows;
      bitInfo.bmiHeader.biPlanes         =  1;
      bitInfo.bmiHeader.biSize           =  sizeof(BITMAPINFOHEADER);
      bitInfo.bmiHeader.biCompression    =  BI_RGB;
      bitInfo.bmiHeader.biClrImportant   =  0;
      bitInfo.bmiHeader.biClrUsed        =  0;
      bitInfo.bmiHeader.biSizeImage      =  0;      //winSize.height * winSize.width * * 3;
      bitInfo.bmiHeader.biXPelsPerMeter  =  0;
      bitInfo.bmiHeader.biYPelsPerMeter  =  0;

      // Add header and OPENCV image data to the HDC
      StretchDIBits( hDC, 
                     offsetX, 
                     offsetY,
                     cvImgTmp.cols,
                     cvImgTmp.rows,
                     0, 
                     0,
                     cvImgTmp.cols,
                     cvImgTmp.rows,
                     pcDibBits,
                     & bitInfo, 
                     DIB_RGB_COLORS, 
                     SRCCOPY );

      free(pcDibBits);
   }

   ReleaseDC(pDC);
}