Correct way to send commands directly to printer!

Question

Ok, here is how i do it:

procedure TMainWindow.btnRawPrintClick(Sender: TObject);
begin
  BeginPrint;
  SendStr(#27#69);
  SendStr('MyData');
  SendStr(#10);
  EndPrint;
end;

procedure TMainWindow.SendStr(Text: String);
var
  i: Integer;
  data : Array of Char;
begin
  for i := 1 to Length(Text) do
  begin
    SetLength(data,i);
    data[Pred(i)] := Text[i];
  end;

  if (PrintRawData(printHandle,
                   data,
                   Length(data)) < 0) then begin
    ShowMessage('PrintRawData Failed');
    EndRawPrintPage(printHandle);
    EndRawPrintJob(printHandle);
    exit;
  end;
end;

procedure TMainWindow.BeginPrint;
begin
  printHandle := StartRawPrintJob('EPSON TM-T70 Receipt','ESDPRT001','Test Document');

  if printHandle < 0 then
  begin
    ShowMessage('StartRawPrintJob Failed!');
    exit;
  end;

  if (StartRawPrintPage(printHandle) < 0) then begin
    ShowMessage('StartRawPrintPage Failed!');
    EndRawPrintJob(printHandle);
    exit;
  end;
end;

procedure TMainWindow.EndPrint;
begin
  if (EndRawPrintPage(printHandle) < 0) then begin
    ShowMessage('EndRawPrintPage Failed');
    EndRawPrintJob(printHandle);
    exit;
  end;

  if (EndRawPrintJob(printHandle) < 0) then begin
    ShowMessage('EndRawPrintJob Failed');
    exit;
  end;
end;

Also i changed a little code that i took from here:

function PrintRawData(hPrn : THandle;
                      Buffer : pointer;
                      NumBytes : SpoolInt) : integer;
{$IFDEF WIN32}
var
  BytesWritten : DWORD;
 {$ENDIF}
begin
  NumBytes := NumBytes * 2;    //<-- I added this line
  ...

However, something is wrong as some commands (escape sequences) don't work as expected!

Answer 1

You're using the wrong function. Use Escape, passing the PASSTHROUGH flag as the second parameter. This sends the raw, unprocessed escape codes to the printer directly.

Joe Hecht (formerly of Borland) has posted a unit several times that makes this easier. I found unit PrtRaw here.