Why does GetObject return an BITMAP with null bmBits?

Question

Context: I\'m trying to take a screenshot of another window to feed it into OpenCV. I found some code on the web that should be able to convert a BITMAP to something OpenCV can

Answer 1

From GetObject documentation on MSDN. Please note the second paragraph.

If hgdiobj is a handle to a bitmap created by calling CreateDIBSection, and the specified buffer is large enough, the GetObject function returns a DIBSECTION structure. In addition, the bmBits member of the BITMAP structure contained within the DIBSECTION will contain a pointer to the bitmap's bit values.

If hgdiobj is a handle to a bitmap created by any other means, GetObject returns only the width, height, and color format information of the bitmap. You can obtain the bitmap's bit values by calling the GetDIBits or GetBitmapBits function.