Access violation when open the teechart form at the second time

Question

We're migrating our XE projects to XE5, however, we encountered the access violation exception about teechart during the test.

I've created a test application to recreate the issue. With the test app, it works fine when open the first teechart form but will get the access violation exception when open it second time or open a new form.

Please refer to the attached test app from the following QC (embarcadero).

http://qc.embarcadero.com/wc/qcmain.aspx?d=122729

When debug it with DCUs. The exception happened when notifying TDBChart's OnStateChange event.

procedure TDataSet.DataEvent(Event: TDataEvent; Info: NativeInt);
begin
  ...
  if NotifyDataSources then
  begin
    for I := 0 to FDataSources.Count - 1 do
      FDataSources[I].DataEvent(Event, Info);  // <<---- Access  Violation
    if FDesigner <> nil then FDesigner.DataEvent(Event, Info);
  end;
end;

Answer 1

As David Berneda said at Quality Central:

Its related to using an internal TObjectList generic collection inside DBChart. The code has been improved so the error is fixed now (a new code takes care of destroying the ObjectList items correctly).

As a workaround, you can add this code at your form's OnClose event:

type
  TChartAccess=class(TDBChart);

procedure TOutcomesGraphFm.bbtnCloseClick(Sender: TObject);
begin
  TChartAccess(dbcBar).RemovedDataSource(bsTestScores,bsTestScores.DataSource);

  Close;
end;