通过驱动向打印机发送一段(ESC)控制指令

这个功能看起来挺奇葩的, 写这个是因为有客户在使用驱动连接票据打印机, 但是又要开钱箱, 驱动里只能每张单据都开钱箱, 而这个打印机又不是只打印结帐单

所以就需要用软件控制打印机开钱箱

票据打印机一般都支持ESC/POS指令, 所以就出现了如下代码, 通过这个函数可以吧ESC/POS指令里的开钱箱指令发送给打印机控制开钱箱

同样, 也可以发送别的什么东西, 比如响响蜂鸣器之类的

哦 补充下, 这个代码里使用的是默认打印机, 当然稍微改动下, 就可以先弹出个打印机列表, 然后选择打印机传进去, 这样就可以控制任意打印机了

OpenPrinter(PChar(Printer.Printers[0]), nD, nPPD);

uses
    WinSpool, Printers;


function WritePrtDataForDriver(AData: string; var AErrCode: Byte): Boolean;
var
  nD: Cardinal;
  nPPD: PPrinterDefaults;
  nDocInfo: DOC_INFO_1;
  nDataLength: DWORD;
  nSize: DWORD;
  nReturn: Boolean;
begin
  Result := False;

  AErrCode := 1;
  nD := INVALID_HANDLE_VALUE;
  nPPD := New(PPrinterDefaults);
  try
    with nPPD^ do
    begin
      DesiredAccess := PRINTER_ACCESS_USE;
      pDatatype := nil;
      pDevMode := nil;
    end;
    OpenPrinter(PChar(Printer.Printers[0]), nD, nPPD);
  finally
    Dispose(nPPD);
  end;
  if nD = INVALID_HANDLE_VALUE  then
    Exit;

  with nDocInfo do
  begin
    pDocName := 'Print Document';
    pOutputFile := nil;
    pDatatype := 'RAW';
  end;
  AErrCode := 2;
  if StartDocPrinter(nD, 1, @nDocInfo) <= 0 then
    Exit;
  AErrCode := 3;
  if not StartPagePrinter(nD) then
    Exit;
  AErrCode := 4;
  nDataLength := Length(AData);
  nReturn := WritePrinter(nD, PChar(AData), nDataLength, nSize);
  if (not nReturn) or (nSize <> nDataLength) then
    Exit;
  AErrCode := 5;
  if not EndPagePrinter(nD) then
    Exit;
  AErrCode := 6;
  if not EndDocPrinter(nD) then
    Exit;

  AErrCode := 7;
  if not ClosePrinter(nD) then
    Exit;

  AErrCode := 0;
  Result := True;
end;

附: 获取驱动打印机状态:

var
  i: Integer;
  nPRH: THandle;
  PrinterName:String;
  nBuff: array[0..8192] of Char;
  nSize: DWord;
  pInfo: PPrinterInfo2;
begin
  Memo1.Lines.Clear;
  for i := 0 to Printer.Printers.Count - 1 do
  begin
    if OpenPrinter(PChar(Printer.Printers[i]), nPRH,nil) then
    begin
      if GetPrinter(nPRH, 2, @nBuff, SizeOf(nBuff), @nSize) then
      begin
        pInfo:=PPrinterInfo2(@nBuff);
        Memo1.Lines.Add('Device := ' + Printer.Printers[i]);
        Memo1.Lines.Add('Status := ' + inttostr(pInfo.Status));
        Memo1.Lines.Add('');
      end;
    end;
    ClosePrinter(nPRH);
  end;
end;