Using pins

> > > > >

Each link is attached to what is called a pin. Each pin describes the position of a contact point on a node.

The class IlvPinLinkConnector, which is a subclass of the class IlvLinkConnector, manages the link connections to a node. An instance of the class IlvPinLinkConnector may be installed on a graphic object. This instance holds a set of pins.

When you create an IlvPinLinkConnector instance, it is empty and does not contain any pins. You must provide a set of pins describing the position of the contact points that you need. The pins are defined by the class IlvGrapherPin. This class is an abstract class because its getPosition method is an abstract method. For this reason, you must first create a subclass of the IlvGrapherPin class. Specifying an implementation to the getPosition method enables you to indicate the position of the grapher pin. The signature of this method follows:

IlvPoint getPosition(IlvTransformer t)

The position of the pin depends on the transformer used to draw the node. This transformer is passed to the getPosition method. To compute the position of the pin, you may need to know the position of the node. For its position, use:

IlvGraphic getNode()

You may also decide to allow or inhibit the connection of a certain type of link to this pin. To do so, you overwrite the allow method of your pin, which is called when you create a link with an interactor:

boolean allow(Object oClass, Object dClass, Object linkOrClass, boolean origin)

The interactor is authorized to highlight only the specified pin based on the result of this method.

Once the pin classes are created, you must add the pins to the previously created instance of IlvPinLinkConnector using the following method:

void addPin(IlvGrapherPin pin)

Example: Defining your connection points

This example defines two classes of pins:

The class InPin that allows links to go to the node.
The class OutPin that allows links to come from the node.

The pins of class InPin are placed on the left border of the object and the pins of type OutPin on the right border.

The classes are:

final class InPin extends IlvGrapherPin 
{
  static final int numberOfPins = 5;
  int index; 
   
  public InPin(IlvPinLinkConnector connector, int index) 
  { 
    super(connector); 
    this.index = index; 
  }
 
  protected boolean allow(Object orig, Object dest, 
                          Object linkOrClass, 
                          boolean origin) 
  {
    return !origin; 
  }
 
  public IlvPoint getPosition(IlvTransformer t) 
  { 
    IlvRect bbox = getNode().boundingBox(null); 
    IlvPoint p = new IlvPoint(bbox.x, 
                              bbox.y+(bbox.height/(numberOfPins+1)*
                              (index+1));
    if (t != null) t.apply(p); 
    return p;
  } 
}

In this example, five instances of InPin will be created. Each pin has an index giving its position on the node. The getPosition method returns the position of the pin on the left side of the node according to its index. The allow method returns true only for links going to this pin (parameter origin is false ). The OutPin class is very similar:

final class OutPin extends IlvGrapherPin
{
  static final int numberOfPins = 5;
  int index; 
   
  public OutPin(IlvPinLinkConnector connector, int index)
  {
    super(connector);
    this.index = index; 
  }
 
  protected boolean allow(Object orig, Object dest,
                          Object linkOrClass, boolean origin)
  { 
    return origin;
  }
 
  public IlvPoint getPosition(IlvTransformer t) 
  {
    IlvRect bbox = getNode().boundingBox(null);
    IlvPoint p = new IlvPoint(bbox.x+ bbox.width, 
                              bbox.y+(bbox.height/
                                        (numberOfPins+1))*(index+1));
    if (t != null) t.apply(p);
    return p;
   }
}

The pins are located on the right side and only allow links leaving the node.

If node is a graphic object, the method that adds the pins to the node is:

grapher.addNode(node, 1, false); 
IlvPinLinkConnector lc = new IlvPinLinkConnector(node); 
for (int i = 0; i < 5; i++) { 
  new InPin(lc, i); 
  new OutPin(lc, i); 
}

If you want to connect a link to a particular pin, use the method connectLink of the class IlvPinLinkConnector :

public void connectLink(IlvLinkImage link, IlvGrapherPin pin, boolean origin)

Current section

Contact points