How to draw Straight line by JUNG2?

Question

After do a test by JUNG2, I found all edge line is bent, but not straight line...How to do a straight line for edge by Jung2?

package pkg;

import javax.swing.JFrame;

import edu.uci.ics.jung.algorithms.layout.CircleLayout;
import edu.uci.ics.jung.algorithms.layout.Layout;
import edu.uci.ics.jung.visualization.VisualizationViewer;
import edu.uci.ics.jung.visualization.control.DefaultModalGraphMouse;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.SparseMultigraph;
import edu.uci.ics.jung.visualization.control.ModalGraphMouse;

public class test {
    public static void main(String[] args) {
        // Graph<V, E> where V is the type of the vertices
        // and E is the type of the edges
        Graph<Integer, String> g = new SparseMultigraph<Integer, String>();
        // Add some vertices. From above we defined these to be type Integer.
        g.addVertex((Integer)1);
        g.addVertex((Integer)2);
        g.addVertex((Integer)3);
        // Add some edges. From above we defined these to be of type String
        // Note that the default is for undirected edges.
        g.addEdge("Edge-A", 1, 2);
        g.addEdge("Edge-B", 2, 3);
        // Let's see what we have. Note the nice output from the
        // SparseMultigraph<V,E> toString() method
        // Note that we can use the same nodes and edges in two different graphs.
        System.out.println("The graph g = " + g.toString());

        Layout<Integer, String> layout = new CircleLayout(g);

        VisualizationViewer<Integer,String> vv = new VisualizationViewer<Integer,String>(layout);
        DefaultModalGraphMouse gm = new DefaultModalGraphMouse();
        gm.setMode(ModalGraphMouse.Mode.PICKING);
        vv.setGraphMouse(gm);

        JFrame frame = new JFrame("Simple Graph View");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(vv);
        frame.pack();
        frame.setVisible(true);
    }

}

Follow output result, black line is default, red line that I want to get that: http://www.zhaocs.info/wp-content/uploads/2015/04/test.png

Answer 1

tl;dr:

Call

vv.getRenderContext().setEdgeShapeTransformer(
    new EdgeShape.Line<Integer,String>());

on your VisualizationViewer

---

There are various options for the edge shape in JUNG. These options are implemented as "edge shape transformers", nested classes of the edu.uci.ics.jung.visualization.decorators.EdgeShape class. The default is EdgeShape.QuadCurve which causes the curved edges. Other options include (extracted from the documentation) :

BentLine<V,E>    bent-line between the vertex endpoints.
Box<V,E>         loop with its nadir at the center of the vertex.
CubicCurve<V,E>  CubicCurve between vertex endpoints.
Line<V,E>        straight line between the vertex endpoints.
Loop<V,E>        loop with its nadir at the center of the vertex.
Orthogonal<V,E>  bent-line between the vertex endpoints.
QuadCurve<V,E>   QuadCurve between vertex endpoints.
SimpleLoop<V,E>  loop with its nadir at the center of the vertex.
Wedge<V,E>       isosceles triangle whose apex is at the destination 
                 vertex for directed edges, and as a "bowtie" shape 
                 for undirected edges.