[cairo] Drawing graphs

[James Allsopp]

Hi,
Sorry for the newbieness of this, but I'm trying to find out where to
start. I need a way of producing graphs of data held in a c++ program,
so that when a cursor is held over a square region/pixel  in a 2-d map
plot a graph will appear in a separate window. Another problem is the
data is vast ~500Mb, and it needs to be fast. I'm just wondering if
there are some good guides, if this is actually possible, and if there
are any existing projects which would save me a lot of effort! I'd like
it run on linux box using gnome, if at all possible.

Thanks for any help/suggestions!
Jim