I'm using the JGraphX mxCompactTreeLayout which by default gives me the layout as shown by (A) on the image below. I would like to know if it's possible to achieve what's shown by (B) with JGraphX. The reason for such requirement is that the graph looks clutted if there are many edges from the same source.
Using the EDGESTYLE_ELBOW is not a bad option but if you want to use the layout you can probably adapt the following.
The CompactTreeLayout creates a edge of three points. If you extend the layout, you can edit the first 2 points of the edge to be the x midpoint of the source vertex bounds. Below is an example for vertical layout option of the CompactTreeLayout.
import java.util.List; import java.util.Map; import javax.swing.JFrame; import mxgraph.layout.mxCompactTreeLayout; import mxgraph.layout.mxIGraphLayout; import mxgraph.model.mxGraphModel; import mxgraph.model.mxICell; import mxgraph.swing.mxGraphComponent; import mxgraph.util.mxConstants; import mxgraph.util.mxPoint; import mxgraph.util.mxRectangle; import mxgraph.view.mxGraph; public class FormatEdges extends JFrame { public FormatEdges() { mxGraph graph = new mxGraph(); Object parent = graph.getDefaultParent(); Map<String, Object> edgeStyle = graph.getStylesheet().getDefaultEdgeStyle(); edgeStyle.put(mxConstants.STYLE_ENDARROW, mxConstants.NONE); graph.getModel().beginUpdate(); try { // Create vertexes Object vertex1 = graph.insertVertex(parent, null, "01", 10, 20, 80, 30); Object vertex2 = graph.insertVertex(parent, null, "010", 10, 20, 80, 30); Object vertex3 = graph.insertVertex(parent, null, "011", 10, 20, 80, 30); Object vertex4 = graph.insertVertex(parent, null, "B", 115, 200, 50, 50, "shape=ellipse"); // Connect mxICell edge1 = ((mxICell)(graph.insertEdge(parent, "01", "", vertex1, vertex2))); mxICell edge2 = ((mxICell)(graph.insertEdge(parent, "02", "", vertex1, vertex3))); // Layout mxIGraphLayout layout = new ExtendedCompactTreeLayout(graph); layout.execute(parent); } finally { graph.getModel().endUpdate(); } mxGraphComponent graphComponent = new mxGraphComponent(graph); getContentPane().add(graphComponent); } public static void main(String[] args) { FormatEdges frame = new FormatEdges(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(400, 320); frame.setVisible(true); } public class ExtendedCompactTreeLayout extends mxCompactTreeLayout { public ExtendedCompactTreeLayout(mxGraph graph) { super(graph, false); super.prefVertEdgeOff = 0; } @Override public void execute(Object parent) { // Execute the CompactTreeLayout super.execute(parent); // Modify the edges to ensure they exit the source cell at the midpoint if(!horizontal) { // get all the vertexes Object[] vertexes = ((mxGraphModel)graph.getModel()).getChildVertices(graph.getModel(), graph.getDefaultParent()); for(int i=0; i < vertexes.length; i++) { mxICell parentCell = ((mxICell)(vertexes[i])); // For each edge of the vertex for(int j=0; j < parentCell.getEdgeCount(); j++) { mxICell edge = parentCell.getEdgeAt(j); // Only consider edges that are from the cell if(edge.getTerminal(true) != parentCell) { continue; } mxRectangle parentBounds = getVertexBounds(parentCell); List<mxPoint> edgePoints = edge.getGeometry().getPoints(); // Need to check that there is always 3 points to an edge, but this will get you started mxPoint outPort = edgePoints.get(0); mxPoint elbowPoint = edgePoints.get(1); if(outPort.getX() != parentBounds.getCenterX()) { outPort.setX(parentBounds.getCenterX()); elbowPoint.setX(parentBounds.getCenterX()); } } } } } } } 