Memory error when close form

[MoreWood]

Hello, to search and display information about a product I have the following scenario:

- a form from where a form is opened with a preview camera and a barcode scanner component:

              FCamera: = TFCamera.Create (nil);
              FCamera.OnReadCode: = ReturnOkCodigo;
              TfgAnimationHelper.ShowForm (FCamera);

- in the form where the image is captured and scanned, I have an accept button that executes this CloseForm (true) code:

 

procedure TFCamera.CloseForm (OK: boolean);
begin
  if OK and Assigned (FOnReadCode) and (fgLabCode.Text <> '-') then FOnReadCode (fgLabCode.Text);

  TfgAnimationHelper.HideForm (Self, [TfgAnimationOption.ReleaseOnFinish]);
  FCamera: = nil;
end;

 The FOnReadCode event helps me to retrieve the code that has been read. This works fine executing like this on click button : CloseForm(true); , but if I use a configuration flag (TConfig.JO.B ['closeonread']) to close the form automatically when a barcode is identified, with this code, a memory error occurs (attach log file):

procedure TFCamera.fgBarcodeScanDetected (Sender: TObject;
  const ABarcodes: TArray <FGX.Scanner.Barcode.TfgBarcode>);
begin
 fgLabCode.Text: = ParseaCodigo (ABarcodes [0] .RawData); //. SubString (HOST_FULL.Length);
 if TConfig.JO.B ['closeonread'] then CloseForm (true) else
  begin
   TThread.ForceQueue (nil, procedure begin
    fgBarcodeScan.Active: = False;
   end);
  end;
end;

 

error_camera_preview.txt

[Viktor Akselrod]

Hello.

1) Which version of Delphi are you using?

2) Please attach a call stack from IDE.

3) What happens in the ReturnOkCodigo?

Thank you.

[MoreWood]

Hello, Delphi version is 10.4.1, ReturnOkCodigo makes a http request to a rest service to retrive product info and fill a CollectionView, but as I said  if I call by button click the code CloseForm(true) there is no problem, the problem is when is executed on fgBarcodeScanDetected event.

 

error_events.txt

[Viktor Akselrod]

I have reproduced the problem. Thanks for the report.

[Viktor Akselrod]

Fixed in 1.9.3.0.

[Viktor Akselrod]

Besides the bugfix, please fix the logic as follows:

procedure TFCamera.CloseForm (OK: boolean);
begin
  if FCamera = nil then
    Exit;

  if OK and Assigned (FOnReadCode) and (fgLabCode.Text <> '-') then FOnReadCode (fgLabCode.Text);

  TfgAnimationHelper.HideForm (Self, [TfgAnimationOption.ReleaseOnFinish]);
  FCamera: = nil;
end;

fgBarcodeScanDetected  and TfgAnimationHelper.HideForm both are called asynchronously. 

TfgAnimationHelper.HideForm with TfgAnimationOption.ReleaseOnFinish flag should not be allowed to call more than once, otherwise it will lead to double destruction of the form and memory corruption.

 

[MoreWood]

8 часов назад, Viktor Akselrod сказал:

Besides the bugfix, please fix the logic as follows:

procedure TFCamera.CloseForm (OK: boolean);
begin
  if FCamera = nil then
    Exit;

  if OK and Assigned (FOnReadCode) and (fgLabCode.Text <> '-') then FOnReadCode (fgLabCode.Text);

  TfgAnimationHelper.HideForm (Self, [TfgAnimationOption.ReleaseOnFinish]);
  FCamera: = nil;
end;

fgBarcodeScanDetected  and TfgAnimationHelper.HideForm both are called asynchronously. 

TfgAnimationHelper.HideForm with TfgAnimationOption.ReleaseOnFinish flag should not be allowed to call more than once, otherwise it will lead to double destruction of the form and memory corruption.

 

  Hello, thanks for you reply. Closeform is called only once, either when detecting the barcode if the automatic closing flag is set or if the accept button of the form is pressed. Anyway, I add the verification that it tells me.

[Viktor Akselrod]

Hello.

TfgAnimationHelper.HideForm(Self, [TfgAnimationOption.ReleaseOnFinish]) - this call does not close immediately form.

first plays the animation, then enqueues the deletion and only then deletes the form.
during this time fgBarcodeScanDetected may fire several more times.

so it is important to prevent for double form destruction.

[MoreWood]

12 минут назад, Viktor Akselrod сказал:

Hello.

TfgAnimationHelper.HideForm(Self, [TfgAnimationOption.ReleaseOnFinish]) - this call does not close immediately form.

first plays the animation, then enqueues the deletion and only then deletes the form.
during this time fgBarcodeScanDetected may fire several more times.

so it is important to prevent for double form destruction.

Ok, I added the check if FCamera = nil then Exit, anyway the memory problem persist, I imagine it will solved with new release, thanks.

[Viktor Akselrod]

1 минуту назад, MoreWood сказал:

anyway the memory problem persist, I imagine it will solved with new release

All right. Still need a fix from our side. 

Thank you

[MoreWood]

Hello, confirm that the last version 1.9.3.0 fix this problem, thanks.