Print change text in spool file

Question

I want to make a Windows service in c# that can change some content which is going to print.

For that i have tried to modify the .SPL file which is generated in spool folder in system32.

I have download one sample from http://www.codeproject.com/Articles/10586/EMF-Printer-Spool-File-Viewer

which convert SPL file to Image but I need text which is not possible.

How to change content before making .SPL file or any suggestion.

Example

This is original text

---

In print

This is duplicate text

---

edited as no response get

Is there any way to read directly from printer port in c# application?

Please note that i am using shared usb printer...

serial port programming is useless..

so anyone know read from usb port..

Answer 1

You have to write a virtual printer driver to intercept the print job and modify it before sending the final print to the actual printer.

https://www.leadtools.com/sdk/print/virtual-printer