org.wilmascope.graph
Class Cluster

java.lang.Object
  org.wilmascope.graph.GraphElement
      org.wilmascope.graph.Node
          org.wilmascope.graph.Cluster

public class Cluster
extends Node

a Cluster is a set of Nodes (Node) and Edges (Edge) sharing the same (LayoutEngine). This class is the main interface to the graph package for adding GraphElements to a graph hierarchy.

Version:

$Id: Cluster.java,v 1.15 2004/11/16 01:47:11 tgdwyer Exp $

Author:

Tim Dwyer

Field Summary

Fields inherited from class org.wilmascope.graph.GraphElement

layout, owner, view, visible

Constructor Summary

Cluster()
The default constructor - an empty cluster

Cluster(Cluster original)
Creates a new cluster with duplicate nodes and edges to the argument.

Cluster(NodeView view)
Create a new cluster with the specified NodeView

Method Summary

void	addBalancedEventListener(BalancedEventListener l)
void	addEdge(Edge e) Add an Edgeto the Cluster Note that the edge may not finish up being added to this cluster, it will be added to the lowest common ancestor of the two ends of the edge.
protected void	addInternalEdgeHere(Edge e) Add an internal edge to this cluster...
float	addMass(float newMass) On adding or removing a node from the cluster the mass of the cluster will change, and a positive or negative contribution to the mass will have to be added, not only to this cluster, but to parent clusters as well.
void	addNode(Node node) Add a Nodeto the Cluster
void	addNodes(NodeList startNodes) Add the specified nodes to this cluster
boolean	applyLayout() applies the layout changes calculated in calculateLayout()to the contents of this cluster and all subclusters
void	calculateLayout() Find a new layout for the nodes according to the current graph and layout engine
void	collapse()
void	delete() delete a cluster and its contents
void	draw() draw the element if it's visible
void	expand(GraphCanvas graphCanvas)
EdgeList	getAcyclicEdgeSet_EnhancedGreedy() Uses a tricky heuristic (Eades et al.
EdgeList	getAcyclicEdgeSet_Greedy() Finds an acyclic subset Ea of this cluster's edges E such that |Ea|>=|E|/2 using a simple greedy heuristic (Berger and Shor, 1990).
NodeList	getAllNodes()
EdgeList	getInternalEdges() Get the edges internal to this cluster, ie, only those edges connecting a pair of nodes that are both inside this cluster
LayoutEngine	getLayoutEngine() Get the LayoutEngineused by the cluster
NodeList	getNodes()
Node	getPortalNode(Edge edge) An external edge is one which has one end in this cluster and one end in another cluster that is not a child (or descendent) of this cluster.
void	hideChildren()
boolean	isAncestor(Node node) Check if the specified node is a child of this cluster or one of this cluster's child clusters etc recursively
boolean	isBalanced()
boolean	isExpanded()
void	moveToParent(Node n) shift a Node up from this Cluster to its parent cluster
protected void	remove(GraphElement e) remove a graph element (ie node or edge) from this cluster
protected void	removeEdge(Edge e) Remove an Edgefrom the Cluster.
protected void	removeExternalEdge(Edge e) remove an edge that is external to this cluster.
protected void	removeNode(Node n) remove a Node up from this Cluster
void	setLayoutEngine(LayoutEngine l) Set the LayoutEnginefor the cluster
void	setMass(float newMass) When the mass of this cluster changes, due to an addition or removal of a node from the cluster or by a user call to this method, the mass of the parent cluster must also be recalculated
void	showChildren(GraphCanvas gc)

Methods inherited from class org.wilmascope.graph.Node

getCommonAncestor, getCommonEdges, getDegree, getEdges, getInDegree, getInEdges, getLayout, getMass, getNeighbours, getOutDegree, getOutEdges, getPosition, getProperties, getView, isNeighbour, reposition, setEdges, setLayout, setPosition, setProperties, setView

Methods inherited from class org.wilmascope.graph.GraphElement

getOwner, getUserData, hide, isVisible, setOwner, show, storeUserData

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Cluster

public Cluster()

The default constructor - an empty cluster

Cluster

public Cluster(Cluster original)

Creates a new cluster with duplicate nodes and edges to the argument. References to the original graph elements are kept in userFacade. Does not recurse down clusters.

Parameters:

original -

Cluster

public Cluster(NodeView view)

Create a new cluster with the specified NodeView

Method Detail

getNodes

public NodeList getNodes()

Returns:

a list of the children in this cluster

addNode

public void addNode(Node node)

Add a Nodeto the Cluster

Parameters:

node - the Node to add

getInternalEdges

public EdgeList getInternalEdges()

Get the edges internal to this cluster, ie, only those edges connecting a pair of nodes that are both inside this cluster

Returns:

a list of edges

See Also:

Node.getEdges()

isAncestor

public boolean isAncestor(Node node)

Check if the specified node is a child of this cluster or one of this cluster's child clusters etc recursively

Parameters:

node - node ancestory of

Returns:

true if this cluster is an ancestor of node

moveToParent

public void moveToParent(Node n)

shift a Node up from this Cluster to its parent cluster

Parameters:

n - which Node to remove

removeNode

protected void removeNode(Node n)

remove a Node up from this Cluster

Parameters:

n - which Node to remove

addEdge

public void addEdge(Edge e)

Add an Edgeto the Cluster Note that the edge may not finish up being added to this cluster, it will be added to the lowest common ancestor of the two ends of the edge.

Overrides:

addEdge in class Node

Parameters:

e - the edge to add

getPortalNode

public Node getPortalNode(Edge edge)

An external edge is one which has one end in this cluster and one end in another cluster that is not a child (or descendent) of this cluster. A portal node is a node in this cluster which has an external edge This method looks up the portal node in this cluster for a specific external edge.

Parameters:

edge - an edge external to this cluster

addInternalEdgeHere

protected void addInternalEdgeHere(Edge e)

Add an internal edge to this cluster... If the edge is already a member of this cluster it will be removed and then added again. Nothing like brute force to get the job done.

remove

protected void remove(GraphElement e)

remove a graph element (ie node or edge) from this cluster

removeEdge

protected void removeEdge(Edge e)

Remove an Edgefrom the Cluster. Will work with either an internal or external edge.

Overrides:

removeEdge in class Node

removeExternalEdge

protected void removeExternalEdge(Edge e)

remove an edge that is external to this cluster. If the edge is actually internal nothing will happen. If in doubt call removeEdge(org.wilmascope.graph.Edge)

See Also:

removeEdge(org.wilmascope.graph.Edge)

isExpanded

public boolean isExpanded()

draw

public void draw()

Description copied from class: GraphElement

draw the element if it's visible

Overrides:

draw in class GraphElement

setLayoutEngine

public void setLayoutEngine(LayoutEngine l)

Set the LayoutEnginefor the cluster

getLayoutEngine

public LayoutEngine getLayoutEngine()

Get the LayoutEngineused by the cluster

hideChildren

public void hideChildren()

showChildren

public void showChildren(GraphCanvas gc)

getAllNodes

public NodeList getAllNodes()

Returns:

all children (recursive descendants) of this cluster

collapse

public void collapse()

expand

public void expand(GraphCanvas graphCanvas)

calculateLayout

public void calculateLayout()

Find a new layout for the nodes according to the current graph and layout engine

applyLayout

public boolean applyLayout()

applies the layout changes calculated in calculateLayout()to the contents of this cluster and all subclusters

Returns:

true if all are balanced

delete

public void delete()

delete a cluster and its contents

Overrides:

delete in class Node

addNodes

public void addNodes(NodeList startNodes)

Add the specified nodes to this cluster

addMass

public float addMass(float newMass)

On adding or removing a node from the cluster the mass of the cluster will change, and a positive or negative contribution to the mass will have to be added, not only to this cluster, but to parent clusters as well. The latter is handled by setMass(float)

setMass

public void setMass(float newMass)

When the mass of this cluster changes, due to an addition or removal of a node from the cluster or by a user call to this method, the mass of the parent cluster must also be recalculated

Overrides:

setMass in class Node

addBalancedEventListener

public void addBalancedEventListener(BalancedEventListener l)

isBalanced

public boolean isBalanced()

Returns:

Returns true if the cluster is balanced, meaning layout is not currently in progress.

getAcyclicEdgeSet_Greedy

public EdgeList getAcyclicEdgeSet_Greedy()

Finds an acyclic subset Ea of this cluster's edges E such that |Ea|>=|E|/2 using a simple greedy heuristic (Berger and Shor, 1990).

Returns:

acyclic subset of edges in this cluster

getAcyclicEdgeSet_EnhancedGreedy

public EdgeList getAcyclicEdgeSet_EnhancedGreedy()

Uses a tricky heuristic (Eades et al. 1993) to find an acyclic subset (Ea) of this cluster's edges (E) such that: |Ea|>=|E|/2+|V|/6

Returns:

acyclic subset of edges in this cluster