Missing metafiles in PDF export when run in thread

Infy

Hi,

I have need to include several TChart charts on reports. The charts can have tens of thousands of values in single series. The TCharts are included in reports like this:

void TReportGeneratorForm::setChart(const TfrxReport *frxReport, AnsiString object,TChart *chart)
{
  TfrxPictureView *Picture;
  TMetafile *metafile;
  Picture = (TfrxPictureView*)frxReport->FindObject(object);
  TRect rect(0,0,chart->Width,chart->Height);
  metafile = chart->TeeCreateMetafile(true,rect);
  Picture->Picture->Assign(metafile);
  delete metafile;
}

Because of the vast amount of series values on the TChart's, the metafile is enormous in size and exporting the report to PDF therefore takes some time. During report generation I want to application to be responsive and to give the user possibility to abort the report generation. Obviously this requires the report generation to take place in a separate thread.

However, when I placed the report generation methods in a class inherited from TThread, occasionally the charts disappeared from PDF files or some parts of the series were missing. I debugged the code and the TCharts are refreshed properly and that above code is executed as supposed. I suspect the PDF export is guilty. It sometimes fails to include the metafile in PDF file when run in thread.

The exporting is done like this:

void TReportGeneratorForm::prepareAndExportReport(TfrxReport *report, AnsiString destination, bool open)
{
  report->PrepareReport(true);
  report->ShowProgress = false;
  frxPDFExport->FileName = destination;
  frxPDFExport->OpenAfterExport = open;
  report->Export(frxPDFExport);
}

When the same code is used and the report generation is not done in thread everything works ok!