Charting Library / C++ / Preferably Free

Would anyone know of a C++ Chart library which can be compiled as part of a C++ Application.
I've already looked at Gnuplot which doesn't quiet fit the bill.

Also I've looked at PPlot which unfortunately hasn't been updated for some time and is giving me issues that I can't fix.

It's pretty hard to know which one to choose and very difficult to find.

I want to create charts from user input into a GUI (I'm using WX Widgets). I then want to either place these charts into a PDF or HTML screen and then print it. (I hope this isn't too unrealistic).

Any direction here would be much appreciated.

Thanks so much for the help on previous posts. Great forum.