Re: Debug ASSERT when CDialog::DoModal() from PreTranslateMessage()
On Wed, 6 Feb 2008 11:53:36 -0800 (PST), PeteOlcott <PeteOlcott@gmail.com>
wrote:
What *exactly* does the assertion say? (They're usually at least somewhat
descriptive and come with filename and line number info - for others to
make sense of the latter, you need to state your compiler version.)
Debug Assertion Failed!
My Program's FullPathName
File: wincore.cpp
Line: 886
Surely there's more to it than that? I only have VC9 installed right now,
and my line 886 is:
ASSERT(HWND_TOP == NULL); // same as desktop
I seriously doubt you're asserting on that, but the text of any assertion
is reported in the assertion dialog box.
The Debug Assertion occurs after the original PreTranslateMessage() is
called, it looks like it occurs within this function.
You should be able to determine the exact context by examining the call
stack in the debugger. That will give you a lot more information than you
currently have. You can visit all the stack frames, examine variables, look
at the code that got you there, and so forth.
What message are you handling in PreTranslateMessage?
#define SPECIAL_MESSAGE WM_USER + 1
You shouldn't be using the WM_USER range unless you registered the window
class. Instead, use WM_APP, and either use a const int for C++ or to be
compatible with C, at least use parens around macros:
// C++
const int SPECIAL_MESSAGE = WM_APP+1;
// C
#define SPECIAL_MESSAGE (WM_APP+1)
For more on message ranges, see:
Which message numbers belong to whom?
http://blogs.msdn.com/oldnewthing/archive/2003/12/02/55914.aspx
Which CWnd is the assertion referring to? The "parent" dialog, or the newly
created one?
It looks like it is the parent DialogBox
It would be very helpful to know what "line 886" corresponds to!
Can you invoke the secondary dialog successfully from an ordinary command
message handler, such as that for a button control? (If the answer is no,
you can be certain the PreTranslateMessage issue is a red herring.)
Yes this has been tested and it works fine. I Invoked another
DialogBox from a button on the original DialogBox.
By "another", I suppose you mean the one that's giving you trouble. If I
were to make a wild guess, I'd wonder if you were calling
PreTranslateMessage directly from another thread. That could cause an
assertion when AssertValid checks the handle map. Again, it would be
very helpful to know what your "line 886" is!
--
Doug Harrison
Visual C++ MVP