VertexPaint | Unity 5.3 Vertex Painter | Graphics library

It looks like you're using version 2.1.* of the JUNG libraries (which uses the Guava types in place of the old common-collections-generics types such as Transformer: https://github.com/jrtom/jung/releases), but using an older version of the sample code.

If you use the version of the sample code that comes with 2.1.1, you should be fine.

I was able to get the effect you want in one of the tree sample programs by doing the following: I extended BasicEdgeRenderer and overrode drawSimpleEdge as follows: first, around line 342 and 344, it fills then draws the edge arrow. g.fill(arrow) and g.draw(arrow). Comment out those lines and you will not get the arrow that you don't want. Next, the code checks to see if this is an undirected graph:

Zoom only affects the drawing of XYSeries data; if you draw directly on the canvas, it will be drawn exactly where you specify on the canvas regardless of pan/zoom.

One thing you can do though is to make series to represent your circle and draw the circle there. This will make the circle respond to both pan and zoom actions. The tricky part will be picking enough points to ensure that the circle appears smooth at your highest supported zoom level.