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;