Line Printer Class in C#

• Download source code and example - 23.6 KB

Introduction

This class simplifies the job of printing text on line printers, in C#. I had an application that needed to print on one of such printers, so I ended up writing this helper class. Basically, it's a wrapper for the spooler API (winspool.drv); the text to be printed is sent in "RAW" mode to the spooler so that no graphics printing is involved.

Using the Code

The use of the class is pretty easy. First, the desired printing device is selected by either writing the PrinterName property or by calling the ChoosePrinter() method:

LPrinter MyPrinter = new LPrinter(); // creates the printer object
MyPrinter.ChoosePrinter();// let user choose the printer device

// alternatively:
MyPrinter.PrinterName = "Epson FX-80";
// uses a specific named printer

The actual printing is done like this:

MyPrinter.Open("Document Title Here"); // opens and tells the spooler the document title
MyPrinter.Print("Some text....\r\n");  // actual printing (CR+LFs are needed)
MyPrinter.Print("\x0C");               // sends a form feed (ejects the paper)
MyPrinter.Close();                     // Close the spooler

All methods Open(), Print(), Close(), and ChoosePrinter() return a boolean, in case you want to check if the operation was successful.

Some basic text effects can be achieved by sending control codes to the printer, according to the following table:

Code	Description
14	enlarged characters on
20	enlarged characters off
15	compressed characters on
18	compressed characters off
ESC + "E"	bold characters on
ESC + "F"	bold characters off
12	FF (form feed)

For more code, check the printer's manual.

Points of Interest

Unfortunately, there is no easy way to tell if an installed printer is a line printer or a graphical one (laser or inkjet), so I was not able to filter the print dialog of ChoosePrinter(), making it display only line printers. This means that the user has to choose the right printer.

History

• 29-Sep-2008: First (and possibly only one) version