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comparison org.eclipse.draw2d/src/org/eclipse/draw2d/graph/DirectedGraphLayout.d @ 12:bc29606a740c

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Added dwt-addons in original directory structure of eclipse.org
author Frank Benoit <benoit@tionex.de>
date Sat, 14 Mar 2009 18:23:29 +0100
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1 /*******************************************************************************
2 * Copyright (c) 2003, 2007 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/
13 module org.eclipse.draw2d.graph.DirectedGraphLayout;
14
15 import java.lang.all;
16 import org.eclipse.draw2d.graph.TransposeMetrics;
17 import org.eclipse.draw2d.graph.BreakCycles;
18 import org.eclipse.draw2d.graph.RouteEdges;
19 import org.eclipse.draw2d.graph.InitialRankSolver;
20 import org.eclipse.draw2d.graph.TightSpanningTreeSolver;
21 import org.eclipse.draw2d.graph.RankAssignmentSolver;
22 import org.eclipse.draw2d.graph.PopulateRanks;
23 import org.eclipse.draw2d.graph.VerticalPlacement;
24 import org.eclipse.draw2d.graph.MinCross;
25 import org.eclipse.draw2d.graph.LocalOptimizer;
26 import org.eclipse.draw2d.graph.HorizontalPlacement;
27 import org.eclipse.draw2d.graph.DirectedGraph;
28 import org.eclipse.draw2d.graph.GraphVisitor;
29
30 /**
31 * Performs a graph layout of a <code>DirectedGraph</code>. The directed graph must meet
32 * the following conditions:
33 * <UL>
34 * <LI>The graph must be connected.
35 * <LI>All edge's must be added to the graph's {@link DirectedGraph#edges edges} list
36 * exactly once.
37 * <LI>All nodes must be added to the graph's {@link DirectedGraph#nodes nodes} list
38 * exactly once.
39 * </UL>
40 *
41 * This algorithm will:
42 * <UL>
43 * <LI>break cycles by inverting a set of feedback edges. Feedback edges will have the
44 * flag {@link Edge#isFeedback} set to <code>true</code>. The following statements are
45 * true with respect to the inverted edge. When the algorithm completes, it will invert
46 * the edges again, but will leave the feedback flags set.
47 * <LI>for each node <em>n</em>, assign n to a "rank" R(n), such that: for each edge (m,
48 * n) in n.incoming, R(m)<=R(n)-(m,n).delta. The total weighted edge lengths shall be
49 * no greater than is necessary to meet this requirement for all edges in the graph.
50 * <LI>attempt to order the nodes in their ranks as to minimize crossings.
51 * <LI>assign <em>y</em> coordinates to each node based on its rank. The spacing
52 * between ranks is the sum of the bottom padding of the previous rank, and the top
53 * padding of the next rank.
54 * <LI>assign <em>x</em> coordinates such that the graph is easily readable. The exact
55 * behavior is undefined, but will favor edge's with higher {@link Edge#weight}s. The
56 * minimum x value assigned to a node or bendpoint will be 0.
57 * <LI>assign <em>bendpoints</em> to all edge's which span more than 1 rank.
58 * </UL>
59 * <P>For each NODE:
60 * <UL>
61 * <LI>The x coordinate will be assigned a value >= 0
62 * <LI>The y coordinate will be assigned a value >= 0
63 * <LI>The rank will be assigned a value >=0
64 * <LI>The height will be set to the height of the tallest node on the same row
65 * </UL>
66 * <P>For each EDGE:
67 * <UL>
68 * <LI>If an edge spans more than 1 row, it will have a list of {@link
69 * org.eclipse.draw2d.graph.Edge#vNodes virtual} nodes. The virtual nodes will be
70 * assigned an x coordinate indicating the routing path for that edge.
71 * <LI>If an edge is a feedback edge, it's <code>isFeedback</code> flag will be set,
72 * and if it has virtual nodes, they will be in reverse order (bottom-up).
73 * </UL>
74 * <P>This class is not guaranteed to produce the same results for each invocation.
75 * @author Randy Hudson
76 * @since 2.1.2
77 */
78 public class DirectedGraphLayout {
79
80 List steps;
81
82 /**
83 * @since 3.1
84 */
85 public this() {
86 steps = new ArrayList();
87 init();
88 }
89
90 void init() {
91 steps.add(new TransposeMetrics());
92 steps.add(new BreakCycles());
93 steps.add(new RouteEdges());
94 steps.add(new InitialRankSolver());
95 steps.add(new TightSpanningTreeSolver());
96 steps.add(new RankAssignmentSolver());
97 steps.add(new PopulateRanks());
98 steps.add(new VerticalPlacement());
99 steps.add(new MinCross());
100 steps.add(new LocalOptimizer());
101 steps.add(new HorizontalPlacement());
102 }
103
104 /**
105 * Lays out the given graph
106 * @param graph the graph to layout
107 */
108 public void visit(DirectedGraph graph) {
109 if (graph.nodes.isEmpty())
110 return;
111 for (int i = 0; i < steps.size(); i++) {
112 GraphVisitor visitor = cast(GraphVisitor)steps.get(i);
113 visitor.visit(graph);
114 }
115 for (int i = steps.size() - 1; i >= 0; i--) {
116 GraphVisitor visitor = cast(GraphVisitor)steps.get(i);
117 visitor.revisit(graph);
118 }
119 }
120
121 }