Re: Debugging Challenge - no source available

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: markusszil (markusszil_at_discussions.microsoft.com)
Date: 09/24/04 

Date: Fri, 24 Sep 2004 07:43:08 -0700

Thanks for the tip.

I altered the program start from:

Application.Run(new MyClass());

to:

MyClass a=new MyClass();
Application.Run(a);

And when it crashes I now have an object (a) to inspect. I also added a few
lines to tell if a particular routine (e.g. timer) was executing during the
crash, but it appears that my code is not executing at the time - I suspect
problems inside .net's painting algorithms. I suspect it may have to do with
transparent backgrounds - I previously noticed some bizarre behavior when I
tried to set a control's background to a transparent bitmap (the transparent
region is filled with screen garbage). There's a note in the help file that
transparent images are not supported. I suspect that at times that might
cause some type of memory fault causing .net to crash, but it's hard to know
for sure. I've decided to derive my own control from the label control I'm
having the problem with and override its OnPaint method with nothing, then
generate my own method to cache the label's image over my bitmap and have my
bitmap-based control just render the cached bitmap. Hopefully that will fix
the problem.

Thanks for the tip,
Markus

"Ray Cassick (Home)" wrote:

> My guess might be that some judiciously placed debug.writeline statements
> might be in order to at least help you collect some runtime data as to where
> you were in the code at the time of the crash.
>
> "markusszil" <markusszil@discussions.microsoft.com> wrote in message
> news:5063FA9E-27B3-4DC3-A0C0-957E4464F404@microsoft.com...
> > Hello all,
> >
> > I am working on an application which uses quite a few bitmaps as skins for
> > custom controls.
> >
> > I am getting a very difficult bug to track - my application performs quite
> a
> > few bitmap operations which use a timer to help time-slice so the UI
> remains
> > responsive. At one point, I am setting a flag to indicate to the timer
> that a
> > particular control needs to have its background refreshed. This is placed
> > into a list for future handling. This completes fine. Debugging in the
> timer
> > also doesn't reveal any problems, although it gets rather difficult to
> follow
> > the execution thread.
> >
> > At any rate, at some, not particularly repeatable point, I press F10 and
> > control returns to .net/Windows and I get the error:
> >
> > "A first chance exception of type 'System.ArgumentException' occurred in
> > system.drawing.dll Additional information: Invalid parameter used."
> >
> > The problem is that I don't have any clue as to where the error is
> occurring
> > - the debugger stops at the Application.Run() line, there's no call stack,
> no
> > objects I can evaluate, I'm kinda stuck.
> >
> > If I turn off exception debugging (i.e. set "When the exception is thrown"
> > radio-button to "Continue"), then the error changes to:
> >
> > "An unhandled exception of type 'System.ArgumentException' occurred in
> > system.windows.forms.dll Additional information: Invalid parameter
> used."
> >
> > In both cases, the debugger catches execution at the same point, just
> before
> > shutting the program down.
> >
> > I'm looking for any pointers on steps I can take to at least cause
> execution
> > to pause at some useful point.
> >
> > Thanks,
> > Markus Szillat
>
>
>

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