Port constraint

It is possible to add Port constraints on an edge. These constraints allow to specify the position of the edge relative to target or the source GraphMLNode of the edge. For example:

• Setting the position of the port for the source of an edge relative to the source node sides
• Setting the position of the port for the target of an edge relative to the target node sides

For example in the following diagram you may have a port constraint on the edge between node1 to node2 specifying that the side of the port on the source node is South and the side of the port on the target port is North:

      GraphmlFactory factory = GraphmlFactory.getInstance();
      GraphmlDiagram diagram = factory.newDiagram();

      GraphMLNode node1 = diagram.addNodeWithLabel("node1");
      GraphMLNode node2 = diagram.addNodeWithLabel("node2");

      GraphMLEdge edge = diagram.addEdge(node1, node2);
      edge.setPortConstraint(PortConstraints.SOURCE, PortConstraints.SOUTH); // the edge comes from the South side of node1 (bottom)
      edge.setPortConstraint(PortConstraints.TARGET, PortConstraints.NORTH);  // the edge goes to the North side of node2 (top)

Access the constraints on an edge

The constraints of an edge are defined in the PortConstraints class. The constraints on an edge are retrieved through the GraphMLEdge.getPortConstraints() method.

Setting a constraint on a GraphMLEdge

Setting a constraint on the PortConstraints associated with the edge

To set a constraint on an edge, you can use the PortConstraints.setPortConstraint(short, short) method:

• The first argument specifies if the constraint is applied on the source or the target of the edge
• The second argument specifies on which side the edge must be put

For example, here we specify that the edge origin comes from the SOUTH side of the node origin to the north side of the node destination:

      GraphmlFactory factory = GraphmlFactory.getInstance();
      GraphmlDiagram diagram = factory.newDiagram();

      GraphMLNode node1 = diagram.addNode();
      GraphMLNode node2 = diagram.addNode();

      GraphMLEdge edge = diagram.addEdge(node1, node2);
      PortConstraints constraints = edge.getPortConstraints();
      constraints.setPortConstraint(PortConstraints.SOURCE, PortConstraints.SOUTH); // the edge comes from the South side of node1 (bottom)
      constraints.setPortConstraint(PortConstraints.TARGET, PortConstraints.NORTH);  // the edge goes to the North side of node2 (top)

Or using Strings:

      GraphmlFactory factory = GraphmlFactory.getInstance();
      GraphmlDiagram diagram = factory.newDiagram();

      GraphMLNode node1 = diagram.addNode();
      GraphMLNode node2 = diagram.addNode();

      GraphMLEdge edge = diagram.addEdge(node1, node2);
      PortConstraints constraints = edge.getPortConstraints();
      constraints.setPortConstraint("source", "south"); // the edge comes from the South side of node1 (bottom)
      constraints.setPortConstraint("target", "north");  // the edge goes to the North side of node2 (top)

Setting a constraint directly on the edge

The methods which apply on the PortConstraints class can also be applied directly on the GraphMLEdge class. You can use the following methods:

• The GraphMLEdge.setPortConstraint(short, short) using enumerates
• The GraphMLEdge.setPortConstraint(String, String) using Strings

For example, here we specify that the edge origin comes from the SOUTH side of the node origin to the north side of the node destination:

      GraphmlFactory factory = GraphmlFactory.getInstance();
      GraphmlDiagram diagram = factory.newDiagram();

      GraphMLNode node1 = diagram.addNode();
      GraphMLNode node2 = diagram.addNode();

      GraphMLEdge edge = diagram.addEdge(node1, node2);
      edge.setPortConstraint(PortConstraints.SOURCE, PortConstraints.SOUTH); // the edge comes from the South side of node1 (bottom)
      edge.setPortConstraint(PortConstraints.TARGET, PortConstraints.NORTH);  // the edge goes to the North side of node2 (top)

Or using Strings:

      GraphmlFactory factory = GraphmlFactory.getInstance();
      GraphmlDiagram diagram = factory.newDiagram();

      GraphMLNode node1 = diagram.addNode();
      GraphMLNode node2 = diagram.addNode();

      GraphMLEdge edge = diagram.addEdge(node1, node2);
      edge.setPortConstraint("source", "south"); // the edge comes from the South side of node1 (bottom)
      edge.setPortConstraint("target", "north");  // the edge goes to the North side of node2 (top)

Setting the constraints on all the edges on a GraphMLNode

It is possible to set the constraints on all the edges of a node through the following methods:

• The AbstractGraphMLNode.setFromPortConstraint(short) will set the port constraints for all the edges originating from this node at the same value
• The AbstractGraphMLNode.setToPortConstraint(short) will set the port constraints for all the edges targetting this node at the same value

For example:

      GraphmlFactory factory = GraphmlFactory.getInstance();
      GraphmlDiagram diagram = factory.newDiagram();

      GraphMLNode node1 = diagram.addNode();
      GraphMLNode node2 = diagram.addNode();

      GraphMLEdge edge = diagram.addEdge(node1, node2);
      node1.setFromPortConstraint(PortConstraints.SOUTH); // set all edges originating from this node as coming from the South side of node (bottom)
      node2.setToPortConstraint(PortConstraints.NORTH); // set all edges originating from another node as going to the North side of node (top)