ilog.views.graphlayout

Interface IlvLinkClipInterface

public interface IlvLinkClipInterface

An interface used to customize the computation of the connection points of the links.

This interface is useful when a layout algorithm that supports this customization must place the connection points of the links by clipping the links at the node border. If the node border is the bounding box of the node, no link clip interface is required. However, if the node has a nonrectangular shape such as a triangle, rhombus, or circle, then a link clip interface can be used to correct the link connection point such that it is exactly at the border of the node shape.

Without Link Clipping	Clipping With the Link Clip Interface

The layout algorithm calculates a proposed connection point. This point is usually inside or on the border of the bounding box of the node. The link can be considered as a ray that starts at the proposed connection point and goes through an auxiliary control point. Then the layout algorithm calls getConnectionPoint which should return the point of the ray that is clipped at the node border. The layout algorithm connects to this point instead of the proposed connection point.

The following code is an example of the implementation of the method getConnectionPoint. In this example, the shape of all nodes is an ellipse inside the bounding box of each node.

 public IlvPoint getConnectionPoint(
   IlvGraphModel graphModel, Object node, IlvRect nodeBox,
   Object link, IlvPoint proposedConnectionPoint, IlvPoint auxControlPoint,
   boolean origin)
 {
   // get the intersections between the line through connect and control
   // point and the ellipse at currentNodeBox.
   IlvPoint[] intersectionPoints = new IlvPoint[2];
   int numIntersections = IlvClippingUtil.LineIntersectsEllipse(
     proposedConnectionPoint, auxControlPoint, nodeBox, intersectionPoints);

    // choose the result from the intersections
    return IlvClippingUtil.BestClipPointOnRay(
              proposedConnectionPoint, auxControlPoint,
              intersectionPoints, numIntersections);
 }
 

An example implementation of a link clip interface that handles many standard objects can be found in the source code of Composer.

Since:

JViews 5.0

See Also:

IlvGraphLayout.setLinkClipInterface(ilog.views.graphlayout.IlvLinkClipInterface)

Method Summary

Modifier and Type	Method and Description
IlvPoint	getConnectionPoint(IlvGraphModel graphModel, Object node, IlvRect currentNodeBox, Object link, IlvPoint proposedConnectionPoint, IlvPoint auxControlPoint, boolean origin) Returns the clipped connection point of a link that starts at the proposed connection point of the node and goes through the auxiliary control point.

Method Detail

getConnectionPoint

IlvPoint getConnectionPoint(IlvGraphModel graphModel,
                            Object node,
                            IlvRect currentNodeBox,
                            Object link,
                            IlvPoint proposedConnectionPoint,
                            IlvPoint auxControlPoint,
                            boolean origin)

Returns the clipped connection point of a link that starts at the proposed connection point of the node and goes through the auxiliary control point.

Parameters:

graphModel - The graph model to which the node belongs.

node - The source or target node of the link.

currentNodeBox - The current bounding box of the node. Note: During layout the algorithm may test a connection point without actually moving the node. Therefore, the current bounding box passed as a parameter can be different from the box returned by graphModel.boundingBox(node).

link - The link to be clipped.

proposedConnectionPoint - The proposed connection point of the link.

auxControlPoint - The auxiliary control point. For clipping purposes, the link can be considered as a ray that starts at the proposed connection point and goes through the auxiliary control point.

origin - true if the node is the source of the link, false if it is the target of the link.

Returns:

The point to which the link should connect.