Example 7.7. Creating a Grouped Graph on the Server

/**
 * Create a simple graph hierarchy containing 
 * nested group nodes
 */
private void createGroupNodes(StyledLayoutGraph graph) {

    // createGroupNode assigns a distinct style
    // and label model to nodes that will be used as group nodes.
    Node outerGroup = createGroupNode(graph, "Outer Group");
    Node innerGroup = createGroupNode(graph, "Inner Group");

    // createLeafNode assigns a distinct style
    // and label model to nodes that will be used as leaf nodes.
    Node leafNode1 = createLeafNode(graph,"Leaf Node");
    Node leafNode2 = createLeafNode(graph,"Leaf Node");
    Node leafNode3 = createLeafNode(graph,"Leaf Node");
    Node leafNode4 = createLeafNode(graph,"Leaf Node");

    // So far, we have a flat graph - no hierarchy 
    // has been defined yet. 
    // Now, we define the hierarchy.

    INodeHierarchy nodeHierarchy = graph.getNodeHierarchy();

    nodeHierarchy.setParent(leafNode1, outerGroup);
    nodeHierarchy.setParent(innerGroup, outerGroup);
    nodeHierarchy.setParent(leafNode2, innerGroup);
    nodeHierarchy.setParent(leafNode3, innerGroup);
    nodeHierarchy.setParent(leafNode4, outerGroup);
    
    // Add some edges.
    graph.createEdge(leafNode2, leafNode1);
    graph.createEdge(leafNode3, leafNode2);
    graph.createEdge(leafNode3, leafNode4);
}

/**
 * Create a node that will be used as leaf node, 
 * using a BevelNodeStyle and a centered label.
 */
private Node createLeafNode(StyledLayoutGraph graph, String labelText) {

    Node node = graph.createNode();
    graph.setSize(node, 60, 40);

    BevelNodeStyle style = new BevelNodeStyle();
    style.setColor(new Color(255, 140, 0));
    graph.setStyle(node, style);

    if (null != labelText) {
      InteriorLabelModel labelModel = new InteriorLabelModel();
      ILabelModelParameter parameter = 
          new InteriorLabelModel.ModelParameter(labelModel,
                        InteriorLabelModel.POSITION_CENTER);
      graph.addLabel(node, new Label(labelText, parameter));
    }

    return node;
}

/**
 * Create a node that will be used as a group node, 
 * using a PanelNodeStyle and
 * a label that is stretched to the node's width.
 */
private Node createGroupNode( StyledLayoutGraph graph, String labelText ) {

    Node groupNode = graph.createNode();

    InteriorLabelModel labelModel = new InteriorLabelModel();
    ILabelModelParameter parameter = 
            new InteriorLabelModel.ModelParameter(labelModel,
                                InteriorLabelModel.POSITION_NORTH);
    Label label = new Label(labelText, parameter);
    graph.addLabel(groupNode, label);

    PanelNodeStyle style = new PanelNodeStyle();
    style.setColor(new Color(128, 128, 128));
    style.setLabelInsetsColor(new Color(192, 192, 192));

    graph.setStyle(groupNode, style);

    // Define some insets for the group node,
    // that will be considered by layout algorithms.
    DataProvider insetsProvider = 
                graph.getDataProvider(GroupingKeys.GROUP_NODE_INSETS_DPKEY);
    if (null != insetsProvider && insetsProvider instanceof DataMap) {
      ((DataMap) insetsProvider).set(groupNode, new Insets(25, 5, 5, 5));
    }

    return groupNode;
}

Example 7.8. Closing a group node

// modify the method createGroupNodes in the
// "create a grouped graph" example to apply folding:
private void createGroupNodes(FoldedLayoutGraph graph) {
    ...
  // insert the new line at the end
  graph.collapse(innerGroup);
}