[igraph] Problem with layouts with GraphML

[Dr Karl]

Hello all,

        I'm a newbie with the iGraph library. I'm using the C version
of the library to generate some graphs with data from a database. I
have successfully generated graphs and written them in .graphml
format. If I open the resulting .graphml with a text editor it has all
the vertices and edges correctly in place. I am using yFiles Flex (by
yWorks) to nicely show the graphs in a Web Application (some Servlets
and Java business logic), this part of the project is already
completed.

        My problem is that if I open the resulting .graphml files with
yEd (by yWorks), all the vertices are centered and it is impossible to
see the graph. If I select a Layout from the menus, yEd automatically
rearranges the vertices so that the graph can be seen.

        So, I'm trying to pre-calculate a layout with iGraph before
writing to .graphml, but after reading the documentation and studying
the examples I'm unable to devise how to do it.

         My problem is that the functions I have found for layout
calculation, like igraph_layout_random or igraph_layout_circle put the
resulting layout in a igraph_matrix_t, and I don't know how to include
this when I generate the graphml, as the function to write graphml
only accepts igraph_t as input.

Any help on this subject would be very much appreciated. Thank you
very much in advance.