Mega Code Archive
How to send data directly to the printer without the PASSTHROUGH command
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Title: How to send data directly to the printer without the PASSTHROUGH command
Question: How can you send data directly to the printer. While your printer driver doesn't support PASSTHROUGH.
Answer:
I had the problem I wanted to write directly to my Barcode-Printer. This, because the Barcode-Printer needs codes to transform to different Barcodes. Delphi only allows you to write on the canvas which ofcourse didn't work. So I tried the Escape functions. The PASSTHROUGH command wasn't supported by my printer driver. Further exploration brought me to the MS pages. The URL: http://msdn.microsoft.com/library/psdk/gdi/prntspol_93g2.htm gives the solution. I translated it to Delphi-code and here it is:
Uses WinSpool;
Function RawDataToPrinter( szPrinterName : String; DataStr : String; dwCount : Integer) : Boolean;
// http://msdn.microsoft.com/library/psdk/gdi/prntspol_93g2.htm
//
// RawDataToPrinter - sends binary data directly to a printer
//
// szPrinterName: NULL-terminated string specifying printer name
// lpData: Pointer to raw data bytes
// dwCount Length of lpData in bytes
//
// Returns: TRUE for success, FALSE for failure.
//
Var hPrinter : THandle;
DocInfo : TDocInfo1;
dwBytesWritten : Integer;
lpData : Array[0..255] of Char;
Begin
// Copy DataStr to lpData
StrPCopy(lpData,DataStr);
// Need a handle to the printer.
If( Not OpenPrinter( PChar(szPrinterName), hPrinter, nil ) ) Then
Begin
Result := FALSE;
Exit;
End;
// Fill in the structure with info about this "document."
DocInfo.pDocName := 'My Document';
DocInfo.pOutputFile := nil;
DocInfo.pDatatype := 'RAW';
// Inform the spooler the document is beginning.
If( StartDocPrinter( hPrinter, 1, @DocInfo ) Begin
ClosePrinter( hPrinter );
Result := FALSE; Exit;
End;
// Start a page.
If( Not StartPagePrinter( hPrinter ) ) Then
Begin
EndDocPrinter( hPrinter );
ClosePrinter( hPrinter );
Result := FALSE;
Exit;
End;
// Send the data to the printer.
If( Not WritePrinter( hPrinter, @lpData, dwCount, dwBytesWritten ) ) Then
Begin
EndPagePrinter( hPrinter );
EndDocPrinter( hPrinter );
ClosePrinter( hPrinter );
Result := FALSE;
Exit;
End;
// End the page.
If( Not EndPagePrinter( hPrinter ) ) Then
Begin
EndDocPrinter( hPrinter );
ClosePrinter( hPrinter );
Result := FALSE;
Exit;
End;
// Inform the spooler that the document is ending.
If( Not EndDocPrinter( hPrinter ) ) Then
Begin
ClosePrinter( hPrinter );
Result := FALSE;
Exit;
End;
// Tidy up the printer handle.
ClosePrinter( hPrinter );
// Check to see if correct number of bytes were written.
If( dwBytesWritten dwCount ) Then
Begin
Result := FALSE;
Exit;
End;
Result := TRUE;
End;
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