> What should I do to avoid problems with the TCanvas? Am I doing something
> very wrong?
> G?ran.

> G?ran Haraldsson <goran.haralds...@vok.lth.se> wrote in message
> news:adl20j$igv$1@news.lth.se...
> > Hi,
> > This is the first time I write to this group. I am trying to controll an
> > interna combustion engine with a programm written in Delphi5. We are
> > measuring the cylinder pressure among other things and plotting this in
> real
> > time on the screen. A couple of times a day I get EInvalidOperation
> "Canvas
> > does not allow drawing" or EStackOverflow in the procedure
> > TCanvas.RequiredState in the unit Graphics.pas.
> > I have tried to enlarge the stack, but it did not help at all. The
program
> > is threaded and run in win98 environment. We use two A/D converters,
where
> > one is connected on the parallellport and the other is a PCI
multifunction
> > card. We also communicate with PIC processors for the injection on the
> other
> > parallellport.

> > What should I do to avoid problems with the TCanvas? Am I doing
something
> > very wrong?
> > G?ran.

> My guess is that you have a GDI resource leak.

> TCanvas.RequiredState is involved in allocating new pens, brushes etc, and
> if your app is not freeing such resources after use, it is possible to run
> out. Have you run a resource checker such as MemProof? With newly
developed
> realtime data acquisition apps it is also a good idea to have a resource
> meter open the whole time they are running just so you can see if they are
> running cleanly or not.

> Dave

> "David Reeve" <drscienti...@powerup.com.au> skrev i meddelandet
> news:jXxL8.5378$3t6.247233@ozemail.com.au...

> > G?ran Haraldsson <goran.haralds...@vok.lth.se> wrote in message
> > news:adl20j$igv$1@news.lth.se...
> > > Hi,
> > > This is the first time I write to this group. I am trying to controll
an
> > > interna combustion engine with a programm written in Delphi5. We are
> > > measuring the cylinder pressure among other things and plotting this
in
> > real
> > > time on the screen. A couple of times a day I get EInvalidOperation
> > "Canvas
> > > does not allow drawing" or EStackOverflow in the procedure
> > > TCanvas.RequiredState in the unit Graphics.pas.
> > > I have tried to enlarge the stack, but it did not help at all. The
> program
> > > is threaded and run in win98 environment. We use two A/D converters,
> where
> > > one is connected on the parallellport and the other is a PCI
> multifunction
> > > card. We also communicate with PIC processors for the injection on the
> > other
> > > parallellport.

> > > What should I do to avoid problems with the TCanvas? Am I doing
> something
> > > very wrong?
> > > G?ran.

> > My guess is that you have a GDI resource leak.

> > TCanvas.RequiredState is involved in allocating new pens, brushes etc,
and
> > if your app is not freeing such resources after use, it is possible to
run
> > out. Have you run a resource checker such as MemProof? With newly
> developed
> > realtime data acquisition apps it is also a good idea to have a resource
> > meter open the whole time they are running just so you can see if they
are
> > running cleanly or not.

> > Dave

> No it is not a GDI resource leak. I have checked the GDI resources with
> resmon.exe and they are never below 66% free.
> /G?ran.