[SOLVED] Create bidirectional arrows in JUNG

Create bidirectional arrows in JUNG

Is it possible to create bidirectional arrows in JUNG using FRLayout? Ideally, is it possible to have an algorithm that uses these arrows (end-points are arrowheads at both ends) for cases where both a->b and b<-a?

I think it might be related to

 Renderer.Edge<String, String> edgeRenderer = 
        vv.getRenderer().getEdgeRenderer();

but can't see how to get the shapes of the arrowheads

Solution

You could do something like this hack to make (in this case) Curved edges overlay each other:

        vv.getRenderContext().setEdgeShapeTransformer(new Function<String, Shape> () {
            @Override
            public Shape apply(String edge) {
                Pair<String> endpoints = graph.getEndpoints(edge);
                float controlY = 60.f;
                 // use some hacked 'ordering' of the endpoint nodes so that the curve for A->B is on the same side as the curve from B->A
                if (endpoints.getFirst().toString().compareTo(endpoints.getSecond().toString()) < 0) {
                    controlY *= -1;
                }
                return new QuadCurve2D.Float(0.0f, 0.0f, 0.5f, controlY, 1.0f, 0.0f);
            }
        });