c++ - How to display OpenCV Mat on MFC View

Question

I thought displaying OpenCV2 Mat on MFC View is simple but is not. This is only relevant material I found on google. Excuse me for my ignorance but I can't find any other materials showing how to use SetDIBitsToDevice with one dimensional array "data" member returns. More specifically, I need to know how to specify BITMAPINFO for the function. Do I go back to Old C-style OpenCV to work with MFC?

UPDATE:

I found an example of SetDIBitsToDevice which is actually for old C-style OpenCV. But it was straightforward to convert it for OpenCV2. There are things I need to mention to make it work:

1. Bpp method does not work well as Mat's depth returns 0. I just changed like this:

   static int Bpp(cv::Mat img) { return 8 * img.channels(); } 
   

2. Mat does not have origin member. But simply putting 0 is fine for origin argument of FillBitmapInfo method.

Other than that, following code works great. Hope this helps other devs too.

void COpenCVTestView::OnDraw(CDC* pDC)
{
COpenCVTestDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
if (!pDoc)
    return;
if(pDoc->m_cvImage.empty()) return;
// TODO: add draw code for native data here
int height=pDoc->m_cvImage.rows;
int width=pDoc->m_cvImage.cols;
uchar buffer[sizeof( BITMAPINFOHEADER ) + 1024]; 
BITMAPINFO* bmi = (BITMAPINFO* )buffer; 
FillBitmapInfo(bmi,width,height,Bpp(pDoc->m_cvImage),0);
SetDIBitsToDevice(pDC->GetSafeHdc(), 0, 0, width,
    height, 0, 0, 0, height, pDoc->m_cvImage.data, bmi,
    DIB_RGB_COLORS);
}
void COpenCVTestView::FillBitmapInfo(BITMAPINFO* bmi, int width, int height, int bpp, int origin) 
{ 
assert(bmi && width >= 0 && height >= 0 && (bpp == 8 || bpp == 24 || bpp == 32)); 

BITMAPINFOHEADER* bmih = &(bmi->bmiHeader); 

memset(bmih, 0, sizeof(*bmih)); 
bmih->biSize = sizeof(BITMAPINFOHEADER); 
bmih->biWidth = width; 
bmih->biHeight = origin ? abs(height) : -abs(height); 
bmih->biPlanes = 1; 
bmih->biBitCount = (unsigned short)bpp; 
bmih->biCompression = BI_RGB; 

if (bpp == 8) 
{ 
    RGBQUAD* palette = bmi->bmiColors; 

            for (int i = 0; i < 256; i++) 
    { 
        palette[i].rgbBlue = palette[i].rgbGreen = palette[i].rgbRed = (BYTE)i; 
        palette[i].rgbReserved = 0; 
    } 
} 
}

Answer 1

Here is another possible way of displaying OpenCV data in MFC which I use and works great:

IplImage* image// <-- this contains the image you want to display
CvvImage tempdefault;
RECT myrect;   // <-- specifiy where on the screen you want it to be displayed
myrect.top    =  0;
myrect.bottom = _pictureh;
myrect.left   = _picturex;
myrect.right =  _picturew+_picturex;
tempdefault.Create(_pictureh,_picturew,32);
tempdefault.CopyOf(image);
tempdefault.DrawToHDC(pDC->GetSafeHdc(),&myrect);