cgraph rendering of HTML labels

I'm working on a Qt based rendering, using library cgraph, and I'm stuck on HTML labels.

Since I installed Graphviz from source, I noticed that the include with htmllabel_t (htmltable.h) is meant to be private.
Then I tried to generate the xdot attributes, using

if (gvLayout(c.context, c.graph, QString("%1:xdot").arg(algo).toUtf8().data()) == 0)

that seems to work (no error reported), but I don't get any _draw_ or _ldraw_ attached to Agnode_t*.

I'm unable to spot in documentation how to generate such attributes.

Any help welcome.

TIA Carlo

The call to gvLayout() just

The call to gvLayout() just determines node and edge positions for the graph; it doesn't do any "rendering". For that you need to call gvRender() or one of its siblings. For example, the call gvRender(context, graph, "xdot", NULL) will attach the xdot information to the graph as _draw_ and _ldraw_ atributes. In general, once the graph is laid out with gvLayout, you can do many calls to gvRender. Check sections 2.2 and 2.3 of

If I interpret the Qt function correctly, you are calling gvLayout(context, graph,"dot:xdot"). I was a bit surprised that that worked, but it does, probably because we just do a strncmp() on the string. In any case, the "xdot" is unused by gvLayout().

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