CImage ReleaseDC Exception Mystery

I have been applying the CImage class within a Visual C++/MFC DLL.  I am experiencing a mysterious exception in atlimage.h line 1217 when I call CImage::GetPixel(0,0).  The offending statement is:

hBitmap = HBITMAP( ::SelectObject( m_hDC, m_hOldBitmap ) );
ATLASSERT( hBitmap == m_hBitmap );

I have successfully loaded an 8x13 jpg 24 bpp image from disk and the pixel value is successfully read, yet the m_hOldBitmap member is null and thus SelectObject returns null.  The m_hBitmap member is valid and thus does not match hBitmap.

Has anyone experienced this error and found a solution?

Thanks!
fredsmullinAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

fredsmullinAuthor Commented:
Please disregard the question.  I found that it was operator error with CImage use.

If you use the CImage assignment operator, CImage a = CImage b, it merely copies the HBITMAP value from b to a.  But when b is destroyed, it destroys the HBITMAP as well.  But, a has no idea this has occurred and any subsequent operations will result in exceptions being generated.

The proper way to assign from one CImage to another is to use CImage::Attach and CImage::Detach functions.  This only moves the HBITMAP from one class to the next, but prevents it from being shared between two classes.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Editors IDEs

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.