draw_hierarchy(): Improve efficiency of "hshortcuts" option

src/graph/draw/graph_cairo_draw.cc

@@ -2150,7 +2150,7 @@ struct enum_from_int
 };
 
 void get_cts(GraphInterface& gi, GraphInterface& tgi, boost::any otpos,
-             boost::any obeta, boost::any octs, bool);
+             boost::any obeta, boost::any octs, bool, size_t);
 
 BOOST_PYTHON_MODULE(libgraph_tool_draw)
 {

src/graph/draw/graph_tree_cts.cc

@@ -128,7 +128,8 @@ void get_control_points(vector<size_t>& path, PosProp pos, double beta,
 }
 
 template <class Graph>
-void tree_path(Graph& g, size_t s, size_t t, vector<size_t>& path)
+void tree_path(Graph& g, size_t s, size_t t, vector<size_t>& path,
+               size_t max_depth)
 {
     vector<size_t> s_root;
     vector<size_t> t_root;
@@ -138,7 +139,7 @@ void tree_path(Graph& g, size_t s, size_t t, vector<size_t>& path)
     size_t v = s;
     size_t u = t;
 
-    while (v != u)
+    while (v != u && s_root.size() < max_depth)
     {
         typename graph_traits<Graph>::in_edge_iterator e, e_end;
         tie(e, e_end) = in_edges(v, g);
@@ -200,7 +201,8 @@ void pack(vector<point_t>& cp, vector<T>& ncp)
 struct do_get_cts
 {
     template <class Graph, class Tree, class PosProp, class BProp, class CMap>
-    void operator()(Graph& g, Tree* t, PosProp tpos, BProp beta, CMap cts, bool is_tree) const
+    void operator()(Graph& g, Tree* t, PosProp tpos, BProp beta, CMap cts,
+                    bool is_tree, size_t max_depth) const
     {
         vector<size_t> path;
         vector<point_t> cp;
@@ -215,7 +217,7 @@ struct do_get_cts
 
             path.clear();
             if (is_tree)
-                tree_path(*t, u, v, path);
+                tree_path(*t, u, v, path, max_depth);
             else
                 graph_path(*t, u, v, path);
             cp.clear();
@@ -239,7 +241,7 @@ struct get_pointers
 };
 
 void get_cts(GraphInterface& gi, GraphInterface& tgi, boost::any otpos,
-             boost::any obeta, boost::any octs, bool is_tree)
+             boost::any obeta, boost::any octs, bool is_tree, size_t max_depth)
 {
     typedef property_map_type::apply<vector<double>,
                                      GraphInterface::edge_index_map_t>::type
@@ -253,7 +255,7 @@ void get_cts(GraphInterface& gi, GraphInterface& tgi, boost::any otpos,
 
     run_action<>()
         (gi, std::bind(do_get_cts(), placeholders::_1, placeholders::_2,
-                       placeholders::_3, beta, cts, is_tree),
+                       placeholders::_3, beta, cts, is_tree, max_depth),
          get_pointers::apply<graph_tool::detail::always_directed>::type(),
          vertex_scalar_vector_properties())
         (tgi.GetGraphView(), otpos);

src/graph_tool/draw/cairo_draw.py

@@ -1226,7 +1226,8 @@ def transform_scale(M, scale):
                              scale / np.sqrt(2))
     return np.sqrt(p[0] ** 2 + p[1] ** 2)
 
-def get_hierarchy_control_points(g, t, tpos, beta=0.8, cts=None, is_tree=True):
+def get_hierarchy_control_points(g, t, tpos, beta=0.8, cts=None, is_tree=True,
+                                 max_depth=None):
     r"""Return the Bézier spline control points for the edges in ``g``, given the hierarchical structure encoded in graph `t`.
 
     Parameters
@@ -1253,6 +1254,9 @@ def get_hierarchy_control_points(g, t, tpos, beta=0.8, cts=None, is_tree=True):
     is_tree : ``bool`` (optional, default: ``True``)
         If ``True``, ``t`` must be a directed tree, otherwise it can be any
         connected graph.
+    max_depth : ``int`` (optional, default: ``None``)
+        If supplied, only the first ``max_depth`` bottom levels of the hierarchy
+        will be used.
 
 
     Returns
@@ -1326,13 +1330,16 @@ def get_hierarchy_control_points(g, t, tpos, beta=0.8, cts=None, is_tree=True):
     else:
         beta = beta.copy("double")
 
+    if max_depth is None:
+        max_depth = t.num_vertices()
+
     tu = GraphView(tu, skip_vfilt=True)
     libgraph_tool_draw.get_cts(u._Graph__graph,
                                tu._Graph__graph,
                                _prop("v", tu, tpos),
                                _prop("e", u, beta),
                                _prop("e", u, cts),
-                               is_tree)
+                               is_tree, max_depth)
     return cts
 
 #
@@ -1590,24 +1597,13 @@ def draw_hierarchy(state, pos=None, layout="radial", beta=0.8, ealpha=0.4,
         dist = shortest_distance(t, source=root)
         hvvisible.fa = dist.fa >= hide
 
-    hevisible = t.new_edge_property("bool", True)
-    if hshortcuts > 0:
-        root = t.vertex(t.num_vertices() - 1)
-        dist = shortest_distance(t, source=root)
-        nodes = [v for v in t.vertices() if dist[v] <= hshortcuts]
-        for v in nodes:
-            for u in nodes:
-                if u == v:
-                    continue
-                t.add_edge(u, v)
-
     pos = g.own_property(tpos.copy())
 
     if verbose:
         print("getting cts...")
 
     cts = get_hierarchy_control_points(g, t, tpos, beta,
-                                       is_tree=hshortcuts == 0)
+                                       max_depth=len(state.levels) - hshortcuts)
 
     if verbose:
         print("done.")
@@ -1679,8 +1675,7 @@ def draw_hierarchy(state, pos=None, layout="radial", beta=0.8, ealpha=0.4,
 
     t_orig = t
     t = GraphView(t,
-                  vfilt=lambda v: int(v) >= g.num_vertices(True) and hvvisible[v],
-                  efilt=hevisible)
+                  vfilt=lambda v: int(v) >= g.num_vertices(True) and hvvisible[v])
     if verbose:
         print("joining graphs")
     props = [(pos, tpos),