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Mark Payton · Guest

Dear All,

I hope you can point me in the right direction. (I Can provide source if you
like) D6

I have a Grid component descended from TDrawGrid.

It consists of overridden procedures

constructor create(AOwner: TComponent); override;
Destructor Destroy; Override;
Procedure SizeChanged(OldColCount, OldRowCount:integer); override;
procedure MouseMove(Shift: TShiftState; X, Y: Integer); override;

and other custom procedures

each of which has the "inherited" in front of the code before my code
starts

Intermittently I experience Access Violations when I move my mouse "OUT" of
the control (even when the control is invisible).
Looking at the map file for my exe it points to CONTROLS.PAS -
ScreenToClient (or ClientToScreen?).

As it is extremely unlikely CONTROLS.PAS is faulty I am looking into any of
my code that is faulty (as this is my first component I reckon its a fair
bet!)

I really can't explain this.

Can anyone point me in the right direction.

Thanks in complete Desperation.

p.s. I can provide the source code on request.

Regards

Mark

Kurt Barthelmess · Guest

"Mark Payton" <mark.payton (AT) derbyshire (DOT) gov.uk> wrote:

Mark Payton · Guest

Many Thanks

Here Goes, the wierd thing is this NEVER happens in the IDE environment, how
would I debug it then?

procedure TMarkPaytonGrid.MouseMove(Shift: TShiftState; X, Y: Integer);
var
Column,Row: Integer;
T: TRect;
APoint: TPoint;
txt: textfile;
begin
try
inherited mousemove(Shift, X, Y);
APoint:=Point(X,Y);
MouseToCell(X, Y, Column, Row);
if (Column>=0) or (Row>=0) then
begin
t:=CellRect(Column,Row);
RCellRecord:=CellPointers[(Row*ColCount)+(Column)];
Hint:=RCellRecord^.Hint;
Application.ShowHint:=True;
GetCursorPos(aPoint);
Application.ActivateHint(APoint);
end;
except on E: Exception do
begin
assignfile(txt,'c:TMarkPaytonGridMouseMove.txt');
ReWrite(txt);
Writeln(txt,e.message);
CloseFile(txt);
end;
end;

end;

"Kurt Barthelmess (TeamB)" <kbarthelmess (AT) compuserve (DOT) com> wrote

Marc Rohloff · Guest

Why don't you comment out sections of your code until the error
dissappears or add logging to a text file?
Off hand I would suspect that CellPointers or RCellRecord is not valid
(You didn't show all the rest of your code)
I have also found that the Row and Column values in a grid aren't always
valid (for example while deleting or inserting rows).

Marc

Michael Mount · Guest

Mark,

Mark Payton · Guest

Thanks to all, I'll give all suggestions a try!

I'll report back and let you know

Regards

Mark

"Michael Mount" <mmount (AT) turbont (DOT) net> wrote

Mark Payton · Guest

Ok, now this has got me confused!

I have checked that the debug DCU's had been included in the project and
noticed that it wasn;t.

The only change I made was to include them.

Now I can't get it to fall over (so far), weird!

I'm pleased, but I would like to pin down the bit of code that caused the
error.

How should I proceed? or shall I leave it?

Regards

Mark

"Mark Payton" <mark.payton (AT) derbyshire (DOT) gov.uk> wrote