Question

I get errors like “List index out of bounds” when sending a QuickReport report to the selected printer as the Printer.Printers stringlist is accessed.

exception class   : EStringListError
exception message : List index out of bounds (6).

main thread ($1594c):
00479559 skdata.exe   Classes   5060 TStringList.GetObject
004a258b skdata.exe   Printers   581 TPrinter.GetPrinter
007ca744 skdata.exe   QRPrntr   3208 TPrinterSettings.ApplySettings
007cb5bb skdata.exe   QRPrntr   3995 TQRPrinter.BeginDoc
007be227 skdata.exe   QuickRpt  4645 TCustomQuickRep.CreateReport
007be909 skdata.exe   QuickRpt  4853 TCustomQuickRep.Print
00859bc7 skdata.exe   PostLst    142 TPostSpecListReport.Print

I’ve added logging that shows that the list of printers (Printer.Printers) has changed just before the error happened. I guess the list of printers can change if a network printer is switched off, if the network is down, and for other reasons too.

How to handle this situation? In Delphi the selected printer is given by the Printer.PrinterIndex, but if the list of printers is changed, then this index is not valid anymore.

I can only think of one solution which is to present the select-printer dialog before every print, in other words not to rely in Printer.PrinterIndex being correct from one print job to the next. But that could be quite annoying to the user.

Ideally the selected printer should be stored as a GUID or by name. That would make it more reliable.

I’ve searched this forum as well as the Embarcadero forum but haven’t found any mention of this kind of problem. So maybe there’s something simple here that I’ve overlooked?

I use Delphi 2007 and QuickReport 5.

Answer 1

You can store the printer name, if you’d like, and assign it in the OnBeforePrint event handler or in the constructor of the report. If you don’t want to hard-code it, store it in the registry or an ini file.

type
  TMyForm = class(TForm)
  ....
  private
    FPrinterName: string;
  published
    ....
  end;

implementation

uses
  Printers;

procedure TMyForm.FormCreate(Sender: TObject);
begin
  // Set, or read from registry or ini file
  FPrinterName := 'My LaserJet Printer';
end;

procedure TMyForm.PrintReportButtonClick(Sender: Object);
begin
  // Create report and set up. Select stored printer, or set to default
  // printer if none is stored
  QuickRep1.PrinterSettings.PrinterIndex := Printers.IndexOf(FPrinterName);
  QuickRep1.Print;
  // Clean up - free report, etc.
end;