Short answer : No, it can’t.
There is also no way to directly access the
backbuffer. You can blit the frontbuffer via
BitBlt into your BMP-DC or can with the help
of glReadPixels read the back/frontbuffer in
all standard GL implementations. If you use
BitBlt there’s the problem, that if there’s
a window in front of your GL-DC, that the
area overlapping yours would be blitted into
the BMP as well, so the only “clean” way to
do is using glReadPixels…unfortunately this
is the slowest way as well.
I read an article on nvidia.developers.com about using a p(ixel) buffer for offscreen rendering. There is also a sample in their ogl SDK.
Also in the OpenGL SUperBible second edition is an example for offscreen rendering to a bitmap.
When you crate your Opengl RC you use a PIXELFORMATDESCRIPTOR struct there you can specify a PFD_DRAW_BITMAP flag. according with a properly offscreen HDC you could do what you want.
to get details look at the sources above and/or the win32sdk help