Re: Pixel format from DC/HBITMAP?

From:

"David Ching" <dc@remove-this.dcsoft.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Fri, 09 Mar 2007 20:57:41 GMT

Message-ID:

<9TjIh.304$JZ3.247@newssvr13.news.prodigy.net>

<dpeterson@viztek.net> wrote in message
news:1173465403.186955.114720@s48g2000cws.googlegroups.com...

Hello,

I'm having trouble retrieving information about the display format
used by a DC and its selected HBITMAP. In essense, I am trying to
create a backbuffer that matches the format used by the corresponding
window. I get a handle to the window's DC, and a handle to the HBITMAP
currently selected into that DC.

We are using a multi-monitor display. The window in question is on an
8-bit grayscale display.

-GetPixelFormat on the window DC fails.
-GetObject() on the window HBITMAP fails (with both BITMAP and
DIBSECTION).
-Bringing the HBITMAP into a GDI+ Bitmap object and using
GetPixelFormat returns the standard PixelFormat32bppRGBA, which is
incorrect.
-Bringing the window DC into a GDI+ Graphics object and using that as
the target when constructing backbuffer Bitmap fails.

Any ideas? Is there another way to retrieve some sort of pixel format
(keep in mind there are three displays connected) or am I doing
something wrong?

Try the same steps but don't use your memory DC/bitmap. Instead, use the DC
you used to create the memory DC (you probably used CreateCompatibleDC(). I
believe I had the same issue (but my memory is foggy) where the memory DC
did not return good results but the physical DC did.

-- David