Aha,
aber das macht doch nichts laut
http://www.foolabs.com/xpdf/about.html
sind die 2 Bedingungen:
* If you are redistributing unmodified copies of Xpdf (or any of the Xpdf tools) in binary form, you need to include all of the documentation: README, man pages (or help files), and COPYING. The README file contains a pointer to a web page with the source code, which satisfies the GPL requirement as far as I am concerned. You are, of course, welcome to distribute the source code as well.
* If you are incorporating the Xpdf source code into another program, and you are distributing that program, you'll need to release your program under the GPL, which means you'll have to make the full source available. This also applies if you are making changes to the Xpdf tools.
Und wenn du xpdf nur unmodifiziert mitlieferst und einfach nur auf die api zugreifst wiedersprichst du nicht der Lizenz. Also steht der Verwendung nichts im wege. Du must nur deinen Sourcecode offenlegen wenn du per copy/paste sourcecode kopierst/modifizierst.
Lg
tom