I recently open sourced a utility which uses PDFtoPrinter.exe.
Improve your utility to easily make that
PDFtoPrinter configurable (if your utility is a command-line one, add some option like
--printer-command=). For example, on Linux, that command is usually
lpr (using CUPS). That printer command could even be a
.bat script (itself running
PDFtoPrinter and also doing some logging) provided by your user.
Then some user might rewrite on his own (perhaps even as an open source program) a functional equivalent of
PDFtoPrinter and does not even use that proprietary software. And perhaps some more or less equivalent to
PDFtoPrinter, but open source, programs already exist for your operating system.
Other users could play with their
PATH variable and symbolic links to use their own variant of
By enabling your user to easily change that particular
PDFtoPrinter command used by your open source program, you weaken the relation between your program and that proprietary utility (and in front of a legal court - should you have to legally defend your rights and license -, that would matter a lot).
BTW, in the Unix world,
a2ps is a free software program (GPLv3+) conceptually similar to yours.
PS. Your situation illustrates why I prefer most Linux distributions to even free as in beer operating systems (including a Windows sold with a laptop). I actually never used Windows (but Linux since 1993) on my PCs (both at home and at work). I am a computer scientist aged 60.