Boost C++ Libraries

libs/graph/example/straight_line_drawing.cpp

//=======================================================================
// Copyright 2007 Aaron Windsor
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================
#include <iostream>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/properties.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/property_map/property_map.hpp>
#include <vector>

#include <boost/graph/planar_canonical_ordering.hpp>
#include <boost/graph/is_straight_line_drawing.hpp>
#include <boost/graph/chrobak_payne_drawing.hpp>
#include <boost/graph/boyer_myrvold_planar_test.hpp>

using namespace boost;

// a class to hold the coordinates of the straight line embedding
struct coord_t
{
    std::size_t x;
    std::size_t y;
};

int main(int argc, char** argv)
{
    typedef adjacency_list< vecS, vecS, undirectedS,
        property< vertex_index_t, int > >
        graph;

    // Define the storage type for the planar embedding
    typedef std::vector< std::vector< graph_traits< graph >::edge_descriptor > >
        embedding_storage_t;
    typedef boost::iterator_property_map< embedding_storage_t::iterator,
        property_map< graph, vertex_index_t >::type >
        embedding_t;

    // Create the graph - a maximal planar graph on 7 vertices. The functions
    // planar_canonical_ordering and chrobak_payne_straight_line_drawing both
    // require a maximal planar graph. If you start with a graph that isn't
    // maximal planar (or you're not sure), you can use the functions
    // make_connected, make_biconnected_planar, and make_maximal planar in
    // sequence to add a set of edges to any undirected planar graph to make
    // it maximal planar.

    graph g(7);
    add_edge(0, 1, g);
    add_edge(1, 2, g);
    add_edge(2, 3, g);
    add_edge(3, 0, g);
    add_edge(3, 4, g);
    add_edge(4, 5, g);
    add_edge(5, 6, g);
    add_edge(6, 3, g);
    add_edge(0, 4, g);
    add_edge(1, 3, g);
    add_edge(3, 5, g);
    add_edge(2, 6, g);
    add_edge(1, 4, g);
    add_edge(1, 5, g);
    add_edge(1, 6, g);

    // Create the planar embedding
    embedding_storage_t embedding_storage(num_vertices(g));
    embedding_t embedding(embedding_storage.begin(), get(vertex_index, g));

    boyer_myrvold_planarity_test(boyer_myrvold_params::graph = g,
        boyer_myrvold_params::embedding = embedding);

    // Find a canonical ordering
    std::vector< graph_traits< graph >::vertex_descriptor > ordering;
    planar_canonical_ordering(g, embedding, std::back_inserter(ordering));

    // Set up a property map to hold the mapping from vertices to coord_t's
    typedef std::vector< coord_t > straight_line_drawing_storage_t;
    typedef boost::iterator_property_map<
        straight_line_drawing_storage_t::iterator,
        property_map< graph, vertex_index_t >::type >
        straight_line_drawing_t;

    straight_line_drawing_storage_t straight_line_drawing_storage(
        num_vertices(g));
    straight_line_drawing_t straight_line_drawing(
        straight_line_drawing_storage.begin(), get(vertex_index, g));

    // Compute the straight line drawing
    chrobak_payne_straight_line_drawing(
        g, embedding, ordering.begin(), ordering.end(), straight_line_drawing);

    std::cout << "The straight line drawing is: " << std::endl;
    graph_traits< graph >::vertex_iterator vi, vi_end;
    for (boost::tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi)
    {
        coord_t coord(get(straight_line_drawing, *vi));
        std::cout << *vi << " -> (" << coord.x << ", " << coord.y << ")"
                  << std::endl;
    }

    // Verify that the drawing is actually a plane drawing
    if (is_straight_line_drawing(g, straight_line_drawing))
        std::cout << "Is a plane drawing." << std::endl;
    else
        std::cout << "Is not a plane drawing." << std::endl;

    return 0;
}