cvShowImageHWND.txt

https://gudanrkim.blogspot.com/2014/11/how-to-display-opencv-cvmat-to-mfc.html?_escaped_fragment_

void cvShowImageHWND(HWND hwnd, const CvArr* arr)

{

 SIZE size = { 0, 0 };

 int channels = 0;

 void* dst_ptr = 0;

 const int channels0 = 3;

 int origin = 0;

 CvMat stub, dst, *image;

 bool changed_size = false; // philipg


 if (!hwnd || !arr)

  return; // keep silence here.


 if (CV_IS_IMAGE_HDR(arr))

  origin = ((IplImage*)arr)->origin;


 image = cvGetMat(arr, &stub);


 HDC hdc = ::GetDC(hwnd);

 BITMAP bmp;

 GdiFlush();

 HGDIOBJ h = GetCurrentObject(hdc, OBJ_BITMAP);


 if (h == NULL)return;

 if (::GetObject(h, sizeof(bmp), &bmp) == 0) return;


 size.cx = abs(bmp.bmWidth);

 size.cy = abs(bmp.bmHeight);

 channels = bmp.bmBitsPixel / 8;

 dst_ptr = bmp.bmBits;


 if (size.cx != image->width || size.cy != image->height || channels != channels0)

 {

  changed_size = true;


  uchar buffer[sizeof(BITMAPINFO)+255 * sizeof(RGBQUAD)];

  BITMAPINFO* binfo = (BITMAPINFO*)buffer;


  DeleteObject(SelectObject(hdc, h));


  size.cx = image->width;

  size.cy = image->height;

  channels = channels0;


  FillBitmapInfo(binfo, size.cx, size.cy, channels * 8, 1);


  HBITMAP hbitmap = CreateDIBSection(hdc, binfo, DIB_RGB_COLORS, &dst_ptr, 0, 0);

  h = SelectObject(hdc, hbitmap);


  cvInitMatHeader(&dst, size.cy, size.cx, CV_8UC3, dst_ptr, (size.cx * channels + 3) & -4);

  cvConvertImage(image, &dst, origin == 0 ? CV_CVTIMG_FLIP : 0);

  

  RECT rect;

  GetClientRect(hwnd, &rect);


  StretchDIBits(hdc,
 0, 0, rect.right, rect.bottom, 0, 0, image->width, image->height,
 dst_ptr, binfo, DIB_RGB_COLORS, SRCCOPY);

  DeleteObject(hbitmap);

 }


 InvalidateRect(hwnd, 0, 0);

 ::ReleaseDC(hwnd, hdc);

}