I think Ruport is trying to do what you want by itself. It's a new tool
and is still in development.

I'm sure it is currently quite feasible to do printable data-based
charts using Ruport + RMagick. I think Ruport would appreciate that
kind of contribution, too.

PDF::Writer may be better applicable to your situation than RMagick,
considering Ruport's current stage of development. Check out
http://ruby-pdf.rubyforge.org/pdf-writer/demos/

Cheers,
Dave