>I'm implementing an ActiveX which will allow text editing within the app, but not exporting texts. The texts can be saved, but will be encrypted and not usable outside the app.
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>So far so good, no problem expected yet. However, the app must allow printing. I need to detect printing via a driver which actually exports into a reusable file (PostScript, PDF), and prevent it.
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>Is there a way (API?) to detect which printers may require or offer printing into a file? Or should I just check for usual suspects (anything with PDF, Post Script and Generic/Text in the printer name)?

Why I think all printer offers you to print to a file? Unfortunately I am not able to test this right now, but I think when you have printer prompt window you always have Print to file check box or you can attach printer to FILE port. Of course this will create unreadable file, but if somebody wants She/He will convert it to something readable.