protected void printReportPdf(Common _record)
{
    args args = new args();
    CustInvoiceJour custInvoiceJour = _record;
    SRSPrintDestinationSettings printSettings;
    SalesInvoiceController controller = new SalesInvoiceController();

    args.record(_record);

    pdfPath = WinAPI::getTempPath() + custInvoiceJour.InvoiceId + ".pdf";

    // imposta nome report
    controller.parmReportName(ssrsReportStr(SalesInvoice, Report));

    // get print settings from contract
    printSettings = controller.parmReportContract().parmPrintSettings();

    // set print medium
    printSettings.printMediumType(SRSPrintMediumType::File);
    printSettings.fileFormat(SRSReportFileFormat::PDF);
    printSettings.overwriteFile(true);
    printSettings.fileName(pdfPath);

    // forzo che non vengano cambiati i parametri di stampa che gli passo io
    controller.DEVparmLockDestinationProperties(true);

    // suppress the parameter dialog
    controller.parmShowDialog(false);
    controller.parmArgs(args);

    // start operation
    controller.startOperation();
}

source : http://daxldsoft.blogspot.com/2012/07/print-salesinvoice-packingslip-or.html