{ BP compatible printer unit with extensions

  Copyright (C) 1998-2006 Free Software Foundation, Inc.

  Author: Frank Heckenbach <frank@pascal.gnu.de>

  This file is part of GNU Pascal.

  GNU Pascal is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published
  by the Free Software Foundation; either version 2, or (at your
  option) any later version.

  GNU Pascal is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with GNU Pascal; see the file COPYING. If not, write to the
  Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  02111-1307, USA.

  As a special exception, if you link this file with files compiled
  with a GNU compiler to produce an executable, this does not cause
  the resulting executable to be covered by the GNU General Public
  License. This exception does not however invalidate any other
  reasons why the executable file might be covered by the GNU
  General Public License. }

{$gnu-pascal,I-}
{$if __GPC_RELEASE__ < 20030303}
{$error This unit requires GPC release 20030303 or newer.}
{$endif}

unit Printer;

interface

uses GPC {$ifndef __OS_DOS__}, Pipes {$endif};

var
  { Dos-like systems: writing to a printer device }

  { The file name to write printer output into }
  PrinterDeviceName: PString = @'prn';

  { Unix-like systems: printing via a printer program }

  { The file name of the printer program. If it contains a '/', it
    will be taken as a complete path, otherwise the file name will
    be searched for in the PATH with FSearchExecutable. }
  PrinterCommand: PString = @'lpr';

  { Optional command line parameters for the printer program.
    Ignored when nil. }
  PrinterArguments: PPStrings = nil;

  { How to deal with the printer spooler after the printer pipe is
    closed, cf. the Pipes unit. }
  PrinterPipeSignal : Integer = 0;
  PrinterPipeSeconds: Integer = 0;
  PrinterPipeWait   : Boolean = True;

{ Text file opened to default printer }
var
  Lst: Text;

{ Assign a file to the printer. Lst will be assigned to the default
  printer at program start, but other files can be assigned to the
  same or other printers (possibly after changing the variables
  above). SpoolerOutput, if not Null, will be redirected from the
  printer spooler's standard output and error. If you use this, note
  that a deadlock might arise when trying to write data to the
  spooler while its output is not being read, though this seems
  quite unlikely, since most printer spoolers don't write so much
  output that could fill a pipe. Under Dos, where no spooler is
  involved, SpoolerOutput, if not Null, will be reset to an empty
  file for compatibility. }
procedure AssignPrinter (var f: AnyFile; var SpoolerOutput: AnyFile);

implementation

{$ifdef __OS_DOS__}

procedure AssignPrinter (var f: AnyFile; var SpoolerOutput: AnyFile);
begin
  SetReturnAddress (ReturnAddress (0));
  Assign (f, PrinterDeviceName^);
  RestoreReturnAddress;
  if @SpoolerOutput <> nil then
    begin
      Unbind (SpoolerOutput);
      Rewrite (SpoolerOutput);
      Reset (SpoolerOutput)
    end
end;

{$else}

type
  TPrinterTFDDData = record
    f, SpoolerOutput: PAnyFile
  end;

procedure OpenPrinter (var PrivateData; Mode: TOpenMode);
begin
  Discard (PrivateData);
  if not (Mode in [fo_Rewrite, fo_Append]) then IOError (EPrinterRead, False)
end;

procedure PrinterDone (var PrivateData);
begin
  Dispose (@PrivateData)
end;

{ Be very lazy: don't open the pipe until data are written to it -- not
  as soon as the file is opened because that happens already in the
  initialization of this unit (BP compatibility). }
function WritePrinter (var PrivateData; const Buffer; Size: SizeType): SizeType;
var
  Data: TPrinterTFDDData absolute PrivateData;
  CharBuf: array [1 .. Size] of Char absolute Buffer;
  Process: PPipeProcess;
begin
  { @@ Check status in Close }
  WritePrinter := 0;
  Pipe (Data.f^, Data.SpoolerOutput^, Data.SpoolerOutput^, PrinterCommand^, PrinterArguments^, GetCEnvironment, Process, nil);  { this also makes sure this function won't be called again for this file }
  if InOutRes <> 0 then Exit;
  Process^.Signal  := PrinterPipeSignal;
  Process^.Seconds := PrinterPipeSeconds;
  Process^.Wait    := PrinterPipeWait;
  BlockWrite (Data.f^, CharBuf, Size);
  Dispose (@Data);
  if InOutRes = 0 then WritePrinter := Size
end;

procedure AssignPrinter (var f: AnyFile; var SpoolerOutput: AnyFile);
var p: ^TPrinterTFDDData;
begin
  if @SpoolerOutput <> nil then
    begin
      Unbind (SpoolerOutput);
      Rewrite (SpoolerOutput);
      Reset (SpoolerOutput)
    end;
  SetReturnAddress (ReturnAddress (0));
  New (p);
  RestoreReturnAddress;
  p^.f := @f;
  p^.SpoolerOutput := @SpoolerOutput;
  AssignTFDD (f, OpenPrinter, nil, nil, nil, WritePrinter, nil, nil, PrinterDone, p)
end;

{$endif}

to begin do
  begin
    AssignPrinter (Lst, Null);
    Rewrite (Lst)
  end;

to end do
  Close (Lst);

end.
