ext/OGDF/ogdf/planarity/EmbedderMinDepth.h

   1 /*
   2  * $Revision: 2589 $
   3  *
   4  * last checkin:
   5  *   $Author: gutwenger $
   6  *   $Date: 2012-07-12 23:31:45 +0200 (Do, 12. Jul 2012) $
   7  ***************************************************************/
   8
   9 /** \file
  10  * \brief Computes an embedding of a graph with minimum depth.
  11  *
  12  * \author Thorsten Kerkhof
  13  *
  14  * \par License:
  15  * This file is part of the Open Graph Drawing Framework (OGDF).
  16  *
  17  * \par
  18  * Copyright (C)<br>
  19  * See README.txt in the root directory of the OGDF installation for details.
  20  *
  21  * \par
  22  * This program is free software; you can redistribute it and/or
  23  * modify it under the terms of the GNU General Public License
  24  * Version 2 or 3 as published by the Free Software Foundation;
  25  * see the file LICENSE.txt included in the packaging of this file
  26  * for details.
  27  *
  28  * \par
  29  * This program is distributed in the hope that it will be useful,
  30  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  31  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  32  * GNU General Public License for more details.
  33  *
  34  * \par
  35  * You should have received a copy of the GNU General Public
  36  * License along with this program; if not, write to the Free
  37  * Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  38  * Boston, MA 02110-1301, USA.
  39  *
  40  * \see  http://www.gnu.org/copyleft/gpl.html
  41  ***************************************************************/
  42
  43 #ifdef _MSC_VER
  44 #pragma once
  45 #endif
  46
  47 #ifndef OGDF_EMBEDDER_MIN_DEPTH_H
  48 #define OGDF_EMBEDDER_MIN_DEPTH_H
  49
  50 #include <ogdf/module/EmbedderModule.h>
  51 #include <ogdf/decomposition/BCTree.h>
  52 #include <ogdf/decomposition/StaticSPQRTree.h>
  53
  54 namespace ogdf {
  55
  56 //! Planar graph embedding with minimum block-nesting depth.
  57 /**
  58  * See paper "Graph Embedding with Minimum Depth and Maximum External
  59  * Face" by C. Gutwenger and P. Mutzel (2004) for details.
  60  */
  61 class OGDF_EXPORT EmbedderMinDepth : public EmbedderModule
  62 {
  63 public:
  64         //constructor
  65         EmbedderMinDepth() { }
  66
  67         /**
  68          * \brief Computes an embedding of \a G with minimum depth.
  69          *
  70          * \param G is the original graph.
  71          * \param adjExternal is assigned an adjacency entry in the external face.
  72          */
  73         void call(Graph& G, adjEntry& adjExternal);
  74
  75 private:
  76         /**
  77          * \brief Computes recursively the block graph for every block.
  78          *
  79          * \param bT is a block node in the BC-tree.
  80          * \param cH is a node of bT in the block graph.
  81          */
  82         void computeBlockGraphs(const node& bT, const node& cH);
  83
  84         /**
  85          * \brief Bottom-up-traversal of bcTree computing the values \a m_{cT, bT}
  86          * for all edges \a (cT, bT) in the BC-tree. The length of each vertex
  87          * \f$v \neq c in \a bT\f$ is set to 1 if \f$v \in M_{bT}\f$ and to 0 otherwise.
  88          *
  89          * \param bT is a block vertex in the BC-tree.
  90          * \param cH is a vertex in the original graph \a G.
  91          * \return Minimum depth of an embedding of \a bT with \a cH on the external
  92          *    face.
  93          */
  94         int bottomUpTraversal(const node& bT, const node& cH);
  95
  96         /**
  97          * \brief Top-down-traversal of BC-tree. The minimum depth of the BC-tree-node
  98          * bT is calculated and before calling the function recursively for all
  99          * children of bT in the BC-tree, the nodeLength of the cut-vertex which bT
 100          * and the child have in common is computed. The length of each node is set to
 101          * 1 if it is in M_B and 0 otherwise, except for |M_B| = 1, than it is set to
 102          * 1 if it is in M2 with m2 = \f$\max_{v \in V_B, v != c} m_B(v)\f$ and
 103          * M2 = \f${c \in V_B \ {v} | m_B(c) = m2}\f$.
 104          *
 105          * \param bT is a block vertex in the BC-tree.
 106          */
 107         void topDownTraversal(const node& bT);
 108
 109         /**
 110          * \brief Computes the adjacency list for all nodes in a block and calls
 111          * recursively the function for all blocks incident to nodes in bT.
 112          *
 113          * \param bT is the tree node treated in this function call.
 114          */
 115         void embedBlock(const node& bT);
 116
 117         /**
 118          * \brief Computes the adjacency list for all nodes in a block and calls
 119          * recursively the function for all blocks incident to nodes in bT.
 120          *
 121          * \param bT is the tree node treated in this function call.
 122          * \param cT is the parent cut vertex node of bT in the BC-tree. cT is 0 if bT
 123          *   is the root block.
 124          * \param after is the adjacency entry of the cut vertex, after which bT has to
 125          *   be inserted.
 126          */
 127         void embedBlock(const node& bT, const node& cT, ListIterator<adjEntry>& after);
 128
 129 private:
 130         /** BC-tree of the original graph */
 131         BCTree* pBCTree;
 132
 133         /** an adjacency entry on the external face */
 134         adjEntry* pAdjExternal;
 135
 136         /** all blocks */
 137         NodeArray<Graph> blockG;
 138
 139         /** a mapping of nodes in the auxiliaryGraph of the BC-tree to blockG */
 140         NodeArray< NodeArray<node> > nH_to_nBlockEmbedding;
 141
 142         /** a mapping of edges in the auxiliaryGraph of the BC-tree to blockG */
 143         NodeArray< EdgeArray<edge> > eH_to_eBlockEmbedding;
 144
 145         /** a mapping of nodes in blockG to the auxiliaryGraph of the BC-tree */
 146         NodeArray< NodeArray<node> > nBlockEmbedding_to_nH;
 147
 148         /** a mapping of edges in blockG to the auxiliaryGraph of the BC-tree */
 149         NodeArray< EdgeArray<edge> > eBlockEmbedding_to_eH;
 150
 151         /** saving for each node in the block graphs its length */
 152         NodeArray< NodeArray<int> > nodeLength;
 153
 154         /** an array containing the minimum depth of each block */
 155         NodeArray<int> minDepth;
 156
 157         /** an array saving the length for each edge in the BC-tree */
 158         EdgeArray<int> m_cB;
 159
 160         /**
 161          * M_B = \f${cH \in B | m_B(cH) = m_B}\f$ with m_B = \f$\max_{c \in B} m_B(c)\f$
 162          * and m_B(c) = \f$\max {0} \cup {m_{c, B'} | c \in B', B' \neq B}\f$.
 163          */
 164         NodeArray< List<node> > M_B;
 165
 166         /**
 167          * M2 is empty, if |M_B| != 1, otherwise M_B = {cH}
 168          * M2 = \f${cH' \in V_B \ {v} | m_B(cH') = m2}\f$ with
 169          * m2 = \f$\max_{vH \in V_B, vH != cH} m_B(vH)\f$.
 170          */
 171         NodeArray< List<node> > M2;
 172
 173         /** saves for every node of G the new adjacency list */
 174         NodeArray< List<adjEntry> > newOrder;
 175
 176         /** treeNodeTreated saves for all block nodes in the
 177          *  BC-tree if it has already been treated or not. */
 178         NodeArray<bool> treeNodeTreated;
 179
 180         /** The SPQR-trees of the blocks */
 181         NodeArray<StaticSPQRTree*> spqrTrees;
 182 };
 183
 184 } // end namespace ogdf
 185
 186 #endif