



org.eclipse.draw2d.graph
Class DirectedGraphLayout
java.lang.Object
org.eclipse.draw2d.graph.DirectedGraphLayout

Direct Known Subclasses:

CompoundDirectedGraphLayout
 public class DirectedGraphLayout
 extends java.lang.Object
Performs a graph layout of a DirectedGraph . The directed graph must meet
the following conditions:
 The graph must be connected.
 All edge's must be added to the graph's
edges list
exactly once.
 All nodes must be added to the graph's
nodes list
exactly once.
This algorithm will:
 break cycles by inverting a set of feedback edges. Feedback edges will have the
flag
Edge.isFeedback set to true . The following statements are
true with respect to the inverted edge. When the algorithm completes, it will invert
the edges again, but will leave the feedback flags set.
 for each node n, assign n to a "rank" R(n), such that: for each edge (m,
n) in n.incoming, R(m)<=R(n)(m,n).delta. The total weighted edge lengths shall be
no greater than is necessary to meet this requirement for all edges in the graph.
 attempt to order the nodes in their ranks as to minimize crossings.
 assign y coordinates to each node based on its rank. The spacing
between ranks is the sum of the bottom padding of the previous rank, and the top
padding of the next rank.
 assign x coordinates such that the graph is easily readable. The exact
behavior is undefined, but will favor edge's with higher
Edge.weight s. The
minimum x value assigned to a node or bendpoint will be 0.
 assign bendpoints to all edge's which span more than 1 rank.
For each NODE:
 The x coordinate will be assigned a value >= 0
 The y coordinate will be assigned a value >= 0
 The rank will be assigned a value >=0
 The height will be set to the height of the tallest node on the same row
For each EDGE:
 If an edge spans more than 1 row, it will have a list of
virtual nodes. The virtual nodes will be
assigned an x coordinate indicating the routing path for that edge.
 If an edge is a feedback edge, it's
isFeedback flag will be set,
and if it has virtual nodes, they will be in reverse order (bottomup).
This class is not guaranteed to produce the same results for each invocation.

Since:
 2.1.2
Methods inherited from class java.lang.Object

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

DirectedGraphLayout
public DirectedGraphLayout()

Since:
 3.1
visit
public void visit(
DirectedGraph graph)
 Lays out the given graph


Parameters:

graph  the graph to layout
Copyright (c) IBM Corp. and others 2000, 2007. All Rights Reserved.


