Adding upstream version 1.2.2.upstream/1.2.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 665 insertions, 0 deletions

diff --git a/src/3rdparty/libdepixelize/kopftracer2011.cpp b/src/3rdparty/libdepixelize/kopftracer2011.cpp
new file mode 100644
index 0000000..96784b1
--- /dev/null
+++ b/src/3rdparty/libdepixelize/kopftracer2011.cpp
@@ -0,0 +1,665 @@
+/*  This file is part of the libdepixelize project
+    Copyright (C) 2013 Vinícius dos Santos Oliveira <vini.ipsmaker@gmail.com>
+
+    GNU Lesser General Public License Usage
+    This library is free software; you can redistribute it and/or modify it
+    under the terms of the GNU Lesser General Public License as published by the
+    Free Software Foundation; either version 2.1 of the License, or (at your
+    option) any later version.
+    You should have received a copy of the GNU Lesser General Public License
+    along with this library.  If not, see <http://www.gnu.org/licenses/>.
+
+    GNU General Public License Usage
+    Alternatively, this library may be used under the terms of the GNU General
+    Public License as published by the Free Software Foundation, either version
+    2 of the License, or (at your option) any later version.
+    You should have received a copy of the GNU General Public License along with
+    this library.  If not, see <http://www.gnu.org/licenses/>.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+*/
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <glibmm.h>
+
+#include <algorithm>
+#include "kopftracer2011.h"
+#include "priv/colorspace.h"
+#include "priv/homogeneoussplines.h"
+#include "priv/branchless.h"
+#include "priv/splines-kopf2011.h"
+#include "priv/iterator.h"
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+#include <glibmm/datetime.h>
+#include <iostream>
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+namespace Tracer {
+namespace Heuristics {
+
+int curves(const PixelGraph &graph, PixelGraph::const_iterator a,
+           PixelGraph::const_iterator b);
+bool islands(PixelGraph::const_iterator a, PixelGraph::const_iterator b);
+
+struct SparsePixels
+{
+    enum Diagonal {
+        /**
+         * From (first) the top left corner to (second) the bottom right.
+         */
+        MAIN_DIAGONAL      = 0,
+        /**
+         * From (first) the top right to (second) the bottom left.
+         */
+        SECONDARY_DIAGONAL = 1
+    };
+
+    typedef std::pair<PixelGraph::const_iterator, PixelGraph::const_iterator>
+    Edge;
+    typedef std::pair<Edge, int> EdgeWeight;
+
+    void operator()(const PixelGraph &graph, unsigned radius);
+
+    static bool similar_colors(PixelGraph::const_iterator n,
+                               const guint8 (&a)[4], const guint8 (&b)[4]);
+
+    /*
+     * Precondition: Must be filled according to Diagonal enum.
+     */
+    EdgeWeight diagonals[2];
+};
+
+} // namespace Heuristics
+
+Splines Kopf2011::to_voronoi(const std::string &filename,
+                             const Options &options)
+{
+    return to_voronoi(Gdk::Pixbuf::create_from_file(filename), options);
+}
+
+Splines Kopf2011::to_voronoi(const Glib::RefPtr<Gdk::Pixbuf const> &buf,
+                             const Options &options)
+{
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    SimplifiedVoronoi<Precision, false> voronoi
+        = _voronoi<Precision, false>(buf, options);
+
+    Glib::DateTime profiling_info[2];
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+
+    Splines ret(voronoi);
+
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::Splines construction time: "
+        << profiling_info[1].difference(profiling_info[0])
+        << std::endl;
+
+    return ret;
+#else // LIBDEPIXELIZE_PROFILE_KOPF2011
+    return Splines(_voronoi<Precision, false>(buf, options));
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+}
+
+Splines Kopf2011::to_grouped_voronoi(const std::string &filename,
+                             const Options &options)
+{
+    return to_grouped_voronoi(Gdk::Pixbuf::create_from_file(filename), options);
+}
+
+Splines Kopf2011::to_grouped_voronoi(const Glib::RefPtr<Gdk::Pixbuf const> &buf,
+                             const Options &options)
+{
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    SimplifiedVoronoi<Precision, false> voronoi
+        = _voronoi<Precision, false>(buf, options);
+
+    Glib::DateTime profiling_info[2];
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+
+    HomogeneousSplines<Precision> splines(voronoi);
+
+#else // LIBDEPIXELIZE_PROFILE_KOPF2011
+    HomogeneousSplines<Precision> splines(_voronoi<Precision, false>
+                                          (buf, options));
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::HomogeneousSplines<" << typeid(Precision).name()
+              << ">(Tracer::SimplifiedVoronoi<" << typeid(Precision).name()
+              << ",false>) construction time: "
+              << profiling_info[1].difference(profiling_info[0])
+              << std::endl;
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+    for ( HomogeneousSplines<Precision>::iterator it = splines.begin(),
+              end = splines.end() ; it != end ; ++it ) {
+        for ( HomogeneousSplines<Precision>::Polygon::points_iter
+                  it2 = it->vertices.begin(), end2 = it->vertices.end()
+                  ; it2 != end2 ; ++it2 ) {
+            it2->smooth = false;
+        }
+        for ( HomogeneousSplines<Precision>::Polygon::holes_iter
+                  it2 = it->holes.begin(), end2 = it->holes.end()
+                  ; it2 != end2 ; ++it2 ) {
+            for ( HomogeneousSplines<Precision>::Polygon::points_iter
+                      it3 = it2->begin(), end3 = it2->end()
+                      ; it3 != end3 ; ++it3 ) {
+                it3->smooth = false;
+            }
+        }
+    }
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::Kopf2011::to_grouped_voronoi internal work time: "
+              << profiling_info[1].difference(profiling_info[0])
+              << std::endl;
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+
+    Splines ret(splines, false, options.nthreads);
+
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::Splines construction time: "
+        << profiling_info[1].difference(profiling_info[0])
+        << std::endl;
+
+    return ret;
+#else // LIBDEPIXELIZE_PROFILE_KOPF2011
+    return Splines(splines, false, options.nthreads);
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+}
+
+Splines Kopf2011::to_splines(const std::string &filename,
+                             const Options &options)
+{
+    return to_splines(Gdk::Pixbuf::create_from_file(filename), options);
+}
+
+Splines Kopf2011::to_splines(const Glib::RefPtr<Gdk::Pixbuf const> &buf,
+                             const Options &options)
+{
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    SimplifiedVoronoi<Precision, true> voronoi
+        = _voronoi<Precision, true>(buf, options);
+
+    Glib::DateTime profiling_info[2];
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+
+    HomogeneousSplines<Precision> splines(voronoi);
+
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::HomogeneousSplines<" << typeid(Precision).name()
+        << "> construction time: "
+        << profiling_info[1].difference(profiling_info[0])
+        << std::endl;
+
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+
+    Splines ret(splines, options.optimize, options.nthreads);
+
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::Splines construction time: "
+        << profiling_info[1].difference(profiling_info[0])
+        << std::endl;
+
+    return ret;
+#else // LIBDEPIXELIZE_PROFILE_KOPF2011
+    HomogeneousSplines<Precision> splines(_voronoi<Precision, true>
+                                          (buf, options));
+    return Splines(splines, options.optimize, options.nthreads);
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+}
+
+template<class T, bool adjust_splines>
+SimplifiedVoronoi<T, adjust_splines>
+Kopf2011::_voronoi(const Glib::RefPtr<Gdk::Pixbuf const> &buf,
+                   const Options &options)
+{
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    Glib::DateTime profiling_info[2];
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+    PixelGraph graph(buf);
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::PixelGraph creation time: "
+              << profiling_info[1].difference(profiling_info[0]) << std::endl;
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+    // gdk-pixbuf2 already checks if image size is meaningful, but asserts state
+    // preconditions and will be useful if gdk-pixbuf is replaced later
+    assert(graph.width() > 0);
+    assert(graph.height() > 0);
+
+#ifndef NDEBUG
+    graph.checkConsistency();
+#endif
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+    // This step could be part of the initialization of PixelGraph
+    // and decrease the necessary number of passes
+    graph.connectAllNeighbors();
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::PixelGraph::connectAllNeighbors() time: "
+              << profiling_info[1].difference(profiling_info[0]) << std::endl;
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+#ifndef NDEBUG
+    graph.checkConsistency();
+#endif
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+    // This step can't be part of PixelGraph initilization without adding some
+    // cache misses due to random access patterns that might be injected
+    _disconnect_neighbors_with_dissimilar_colors(graph);
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::Kopf2011::"
+        "_disconnect_neighbors_with_dissimilar_colors(Tracer::PixelGraph) time: "
+              << profiling_info[1].difference(profiling_info[0]) << std::endl;
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+#ifndef NDEBUG
+    graph.checkConsistency();
+#endif
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+    {
+        // edges_safe and edges_unsafe must be executed in separate.
+        // Otherwise, there will be colateral effects due to misassumption about
+        // the data being read.
+        PixelGraph::EdgePairContainer edges = graph.crossingEdges();
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::PixelGraph::crossingEdges() time: "
+              << profiling_info[1].difference(profiling_info[0]) << std::endl;
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+        _remove_crossing_edges_safe(edges);
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+        profiling_info[1] = Glib::DateTime::create_now_utc();
+        std::cerr << "Tracer::Kopf2011::_remove_crossing_edges_safe"
+            "(Tracer::PixelGraph) time: "
+                  << profiling_info[1].difference(profiling_info[0])
+                  << std::endl;
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+#ifndef NDEBUG
+        graph.checkConsistency();
+#endif
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+        profiling_info[0] = Glib::DateTime::create_now_utc();
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+        _remove_crossing_edges_unsafe(graph, edges, options);
+    }
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::Kopf2011::_remove_crossing_edges_unsafe"
+        "(Tracer::PixelGraph) time: "
+              << profiling_info[1].difference(profiling_info[0]) << std::endl;
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+
+#ifndef NDEBUG
+    graph.checkConsistency();
+#endif
+
+    assert(graph.crossingEdges().size() == 0);
+
+#ifdef LIBDEPIXELIZE_PROFILE_KOPF2011
+    profiling_info[0] = Glib::DateTime::create_now_utc();
+
+    SimplifiedVoronoi<T, adjust_splines> ret(graph);
+
+    profiling_info[1] = Glib::DateTime::create_now_utc();
+    std::cerr << "Tracer::SimplifiedVoronoi<" << typeid(T).name() << ','
+              << (adjust_splines ? "true" : "false")
+              << ">(Tracer::PixelGraph) construction time: "
+              << profiling_info[1].difference(profiling_info[0]) << std::endl;
+
+    return ret;
+#else // LIBDEPIXELIZE_PROFILE_KOPF2011
+    return SimplifiedVoronoi<T, adjust_splines>(graph);
+#endif // LIBDEPIXELIZE_PROFILE_KOPF2011
+}
+
+// TODO: move this function (plus connectAllNeighbors) to PixelGraph constructor
+inline void
+Kopf2011::_disconnect_neighbors_with_dissimilar_colors(PixelGraph &graph)
+{
+    using colorspace::similar_colors;
+    for ( PixelGraph::iterator it = graph.begin(), end = graph.end() ; it != end
+              ; ++it ) {
+        if ( it->adj.top )
+            it->adj.top = similar_colors(it->rgba, (it - graph.width())->rgba);
+        if ( it->adj.topright ) {
+            it->adj.topright
+                = similar_colors(it->rgba, (it - graph.width() + 1)->rgba);
+        }
+        if ( it->adj.right )
+            it->adj.right = similar_colors(it->rgba, (it + 1)->rgba);
+        if ( it->adj.bottomright ) {
+            it->adj.bottomright
+                = similar_colors(it->rgba, (it + graph.width() + 1)->rgba);
+        }
+        if ( it->adj.bottom ) {
+            it->adj.bottom
+                = similar_colors(it->rgba, (it + graph.width())->rgba);
+        }
+        if ( it->adj.bottomleft ) {
+            it->adj.bottomleft
+                = similar_colors(it->rgba, (it + graph.width() - 1)->rgba);
+        }
+        if ( it->adj.left )
+            it->adj.left = similar_colors(it->rgba, (it - 1)->rgba);
+        if ( it->adj.topleft ) {
+            it->adj.topleft = similar_colors(it->rgba,
+                                             (it - graph.width() - 1)->rgba);
+        }
+    }
+}
+
+/**
+ * This method removes crossing edges if the 2x2 block is fully connected.
+ *
+ * In this case the two diagonal connections can be safely removed without
+ * affecting the final result.
+ */
+template<class T>
+void Kopf2011::_remove_crossing_edges_safe(T &container)
+{
+    for ( typename T::reverse_iterator it = container.rbegin(),
+              end = container.rend() ; it != end ; ) {
+        /* A | B
+           --+--
+           C | D */
+        PixelGraph::iterator a = it->first.first;
+        PixelGraph::iterator b = it->second.first;
+        PixelGraph::iterator c = it->second.second;
+        PixelGraph::iterator d = it->first.second;
+
+        if ( !a->adj.right || !a->adj.bottom || !b->adj.bottom
+             || !c->adj.right ) {
+            ++it;
+            continue;
+        }
+
+        // main diagonal
+        a->adj.bottomright = 0;
+        d->adj.topleft = 0;
+
+        // secondary diagonal
+        b->adj.bottomleft = 0;
+        c->adj.topright = 0;
+
+        // base iterator is always past one
+        typename T::iterator current = --(it.base());
+        ++it;
+        container.erase(current);
+    }
+}
+
+/**
+ * This method removes crossing edges using the heuristics.
+ */
+template<class T>
+void Kopf2011::_remove_crossing_edges_unsafe(PixelGraph &graph, T &edges,
+                                             const Options &options)
+{
+    std::vector< std::pair<int, int> > weights(edges.size(),
+                                               std::make_pair(0, 0));
+
+    // Compute weights
+    for ( typename T::size_type i = 0 ; i != edges.size() ; ++i ) {
+        /* A | B
+           --+--
+           C | D */
+        PixelGraph::iterator a = edges[i].first.first;
+        PixelGraph::iterator b = edges[i].second.first;
+        PixelGraph::iterator c = edges[i].second.second;
+        PixelGraph::iterator d = edges[i].first.second;
+
+        // Curves heuristic
+        weights[i].first += Heuristics::curves(graph, a, d)
+            * options.curvesMultiplier;
+        weights[i].second += Heuristics::curves(graph, b, c)
+            * options.curvesMultiplier;
+
+        // Islands heuristic
+        weights[i].first += Heuristics::islands(a, d) * options.islandsWeight;
+        weights[i].second += Heuristics::islands(b, c) * options.islandsWeight;
+
+        // Sparse pixels heuristic
+        using Heuristics::SparsePixels;
+        SparsePixels sparse_pixels;
+
+        sparse_pixels.diagonals[SparsePixels::MAIN_DIAGONAL].first
+            = edges[i].first;
+        sparse_pixels.diagonals[SparsePixels::SECONDARY_DIAGONAL].first
+            = edges[i].second;
+
+        sparse_pixels(graph, options.sparsePixelsRadius);
+
+        weights[i].first
+            += sparse_pixels.diagonals[SparsePixels::MAIN_DIAGONAL].second
+            * options.sparsePixelsMultiplier;
+        weights[i].second
+            += sparse_pixels.diagonals[SparsePixels::SECONDARY_DIAGONAL].second
+            * options.sparsePixelsMultiplier;
+    }
+
+    // Remove edges with lower weight
+    for ( typename T::size_type i = 0 ; i != edges.size() ; ++i ) {
+        /* A | B
+           --+--
+           C | D */
+        PixelGraph::iterator a = edges[i].first.first;
+        PixelGraph::iterator b = edges[i].second.first;
+        PixelGraph::iterator c = edges[i].second.second;
+        PixelGraph::iterator d = edges[i].first.second;
+
+        if ( weights[i].first > weights[i].second ) {
+            b->adj.bottomleft = 0;
+            c->adj.topright = 0;
+        } else if ( weights[i].first < weights[i].second ) {
+            a->adj.bottomright = 0;
+            d->adj.topleft = 0;
+        } else {
+            a->adj.bottomright = 0;
+            b->adj.bottomleft = 0;
+            c->adj.topright = 0;
+            d->adj.topleft = 0;
+        }
+    }
+
+    edges.clear();
+}
+
+inline int Heuristics::curves(const PixelGraph &graph,
+                              PixelGraph::const_iterator a,
+                              PixelGraph::const_iterator b)
+{
+    int count = 1;
+    ToPtr<PixelGraph::Node> to_ptr;
+    ToIter<PixelGraph::Node> to_iter(graph.begin());
+
+    // b -> a
+    // and then a -> b
+    for ( int i = 0 ; i != 2 ; ++i ) {
+        PixelGraph::const_iterator it = i ? a : b;
+        PixelGraph::const_iterator prev = i ? b : a;
+        int local_count = 0;
+
+        // Used to avoid inifinite loops in circular-like edges
+        const PixelGraph::const_iterator initial = it;
+
+        while ( it->adjsize() == 2 ) {
+            ++local_count;
+
+            // Iterate to next
+            {
+                // There are only two values that won't be zero'ed
+                // and one of them has the same value of prev
+                guintptr aux = (it->adj.top
+                       * guintptr(to_ptr(graph.nodeTop(it))))
+                    + (it->adj.topright
+                       * guintptr(to_ptr(graph.nodeTopRight(it))))
+                    + (it->adj.right
+                       * guintptr(to_ptr(graph.nodeRight(it))))
+                    + (it->adj.bottomright
+                       * guintptr(to_ptr(graph.nodeBottomRight(it))))
+                    + (it->adj.bottom
+                       * guintptr(to_ptr(graph.nodeBottom(it))))
+                    + (it->adj.bottomleft
+                       * guintptr(to_ptr(graph.nodeBottomLeft(it))))
+                    + (it->adj.left
+                       * guintptr(to_ptr(graph.nodeLeft(it))))
+                    + (it->adj.topleft
+                       * guintptr(to_ptr(graph.nodeTopLeft(it))))
+                    - guintptr(to_ptr(prev));
+                prev = it;
+                it = to_iter(reinterpret_cast<PixelGraph::Node const*>(aux));
+            }
+
+            // Break infinite loops
+            if ( it == initial )
+                return local_count;
+        }
+        count += local_count;
+    }
+
+    return count;
+}
+
+inline void Heuristics::SparsePixels::operator ()(const PixelGraph &graph,
+                                                  unsigned radius)
+{
+    if ( !graph.width() || !graph.height() )
+        return;
+
+    // Clear weights
+    for ( int i = 0 ; i != 2 ; ++i )
+        diagonals[i].second = 0;
+
+    if ( !radius )
+        return;
+
+    // Fix radius/bounds
+    {
+        unsigned x = graph.toX(diagonals[MAIN_DIAGONAL].first.first);
+        unsigned y = graph.toY(diagonals[MAIN_DIAGONAL].first.first);
+        unsigned displace = radius - 1;
+
+        {
+            unsigned minor = std::min(x, y);
+
+            if ( displace > minor ) {
+                displace = minor;
+                radius = displace + 1;
+            }
+        }
+
+        displace = radius;
+
+        if ( x + displace >= unsigned(graph.width()) ) {
+            displace = unsigned(graph.width()) - x - 1;
+            radius = displace;
+        }
+
+        if ( y + displace >= unsigned(graph.height()) ) {
+            displace = unsigned(graph.height()) - y - 1;
+            radius = displace;
+        }
+    }
+
+    if ( !radius )
+        return;
+
+    // Iterate over nodes and count them
+    {
+        PixelGraph::const_iterator it = diagonals[MAIN_DIAGONAL].first.first;
+        for ( unsigned i = radius - 1 ; i ; --i )
+            it = graph.nodeTopLeft(it);
+
+        bool invert = false;
+        for ( unsigned i = 0 ; i != 2 * radius ; ++i ) {
+            for ( unsigned j = 0 ; j != 2 * radius ; ++j ) {
+                for ( int k = 0 ; k != 2 ; ++k ) {
+                    diagonals[k].second
+                        += similar_colors(it, diagonals[k].first.first->rgba,
+                                          diagonals[k].first.second->rgba);
+                }
+                it = (invert ? graph.nodeLeft(it) : graph.nodeRight(it));
+            }
+            it = (invert ? graph.nodeRight(it) : graph.nodeLeft(it));
+
+
+            invert = !invert;
+            it = graph.nodeBottom(it);
+        }
+    }
+
+    int minor = std::min(diagonals[0].second, diagonals[1].second);
+    for ( int i = 0 ; i != 2 ; ++i )
+        diagonals[i].second -= minor;
+    std::swap(diagonals[0].second, diagonals[1].second);
+}
+
+inline bool
+Heuristics::SparsePixels::similar_colors(PixelGraph::const_iterator n,
+                                         const guint8 (&a)[4],
+                                         const guint8 (&b)[4])
+{
+    using colorspace::similar_colors;
+    return similar_colors(n->rgba, a) || similar_colors(n->rgba, b);
+}
+
+inline bool Heuristics::islands(PixelGraph::const_iterator a,
+                                PixelGraph::const_iterator b)
+{
+    if ( a->adjsize() == 1 || b->adjsize() == 1 )
+        return true;
+
+    return false;
+}
+
+} // namespace Tracer
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :