Month: February 2011

To change the way a vertex is rendered, you provide an implementation of the Renderer.Vertex interface. The interface has one function – paintVertex – where you can draw anything you like, like in the graphics of any JComponent. I changed my example, adding 3 nodes: a circle, a square and a rectangle, each one painted with it’s shape and in a different color.

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Point2D;
import javax.swing.JFrame;
import org.apache.commons.collections15.Transformer;
import edu.uci.ics.jung.algorithms.layout.CircleLayout;
import edu.uci.ics.jung.algorithms.layout.Layout;
import edu.uci.ics.jung.graph.DirectedSparseGraph;
import edu.uci.ics.jung.visualization.RenderContext;
import edu.uci.ics.jung.visualization.VisualizationViewer;
import edu.uci.ics.jung.visualization.control.DefaultModalGraphMouse;
import edu.uci.ics.jung.visualization.control.ModalGraphMouse;
import edu.uci.ics.jung.visualization.renderers.Renderer;
import edu.uci.ics.jung.visualization.transform.shape.GraphicsDecorator;

public class JungLearning {
	public static void main(String[] args) {
		DirectedSparseGraph<String, String> g = new DirectedSparseGraph<String, String>();
		g.addVertex("Square");
		g.addVertex("Rectangle");
		g.addVertex("Circle");
		g.addEdge("Edge1", "Square", "Rectangle");
		g.addEdge("Edge2", "Square", "Circle");
		g.addEdge("Edge3", "Circle", "Square");
		VisualizationViewer<String, String> vv =
			new VisualizationViewer<String, String>(
				new CircleLayout<String, String>(g), new Dimension(400,400));
		Transformer<String, String> transformer = new Transformer<String, String>() {
			@Override public String transform(String arg0) { return arg0; }
		};
		vv.getRenderContext().setVertexLabelTransformer(transformer);
		transformer = new Transformer<String, String>() {
			@Override public String transform(String arg0) { return arg0; }
		};
		vv.getRenderContext().setEdgeLabelTransformer(transformer);
		vv.getRenderer().setVertexRenderer(new MyRenderer());

		// The following code adds capability for mouse picking of vertices/edges. Vertices can even be moved!
		final DefaultModalGraphMouse<String,Number> graphMouse = new DefaultModalGraphMouse<String,Number>();
		vv.setGraphMouse(graphMouse);
		graphMouse.setMode(ModalGraphMouse.Mode.PICKING);

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

	static class MyRenderer implements Renderer.Vertex<String, String> {
		@Override public void paintVertex(RenderContext<String, String> rc,
				Layout<String, String> layout, String vertex) {
			GraphicsDecorator graphicsContext = rc.getGraphicsContext();
			Point2D center = layout.transform(vertex);
			Shape shape = null;
			Color color = null;
			if(vertex.equals("Square")) {
				shape = new Rectangle((int)center.getX()-10, (int)center.getY()-10, 20, 20);
				color = new Color(127, 127, 0);
			} else if(vertex.equals("Rectangle")) {
				shape = new Rectangle((int)center.getX()-10, (int)center.getY()-20, 20, 40);
				color = new Color(127, 0, 127);
			} else if(vertex.equals("Circle")) {
				shape = new Ellipse2D.Double(center.getX()-10, center.getY()-10, 20, 20);
				color = new Color(0, 127, 127);
			}
			graphicsContext.setPaint(color);
			graphicsContext.fill(shape);
		}
	}
}

And the results are favorable:

P.D: Yes, I know that the code is ugly, is not OO, has numbers instead of constants, etc… I have no good excuse.

The source code for this example can be found here.