How to convert a printer driver to a stand-alone console application which can generate a printer file containing the bytes to be sent to the printer?

Question

I have a situation where the only way to generate a certain datafile is to print it manually to FILE: under Windows and save it in a file for further processing.

Answer 1

Just to reiterate, probably the simplest capture method is using a new Local Port configured as a filename. You can to monitor the output file as previously discussed to catch the output.

Otherwise, you want to write your own port monitor - not a printer driver or a print processor. All a port monitor does is receive the already rendered data from the printer driver, and sends it to the output device. So writing your own port monitor will allow you to go in and change the output port associated with the existing printer driver to be your own output port, and your port monitor can simply write the data to a file, probably one with a unique filename in a dedicated directory.

Printer drivers are far too complicated for what you want to do, and while a print processor could also capture the output data, you'd probably get entangled in some scantily documented system issues you won't want to have to figure out.

The LocalMon sample in the Windows Driver Kit is THE starting point for writing a port monitor. However, it manages all the system local ports and is quite a bit more complex than you need. In fact, much of it is just likely to confuse you. I'd recommend you start with LocalMon, and compare it to the Redmon source, which is much simpler because it manages a dedicated port. Beware that the Redmon source was taken from localmon long ago and appears to have a few bugs, so use Redmon as a reference and pare back the LocalMon code to what's needed to just write the output to a file.