fix: enhance dissolve and add unit test

Author: barendgehrels

extensions/test/algorithms/dissolve.cpp

@@ -1,7 +1,7 @@
 // Boost.Geometry (aka GGL, Generic Geometry Library)
 // Unit Test
 
-// Copyright (c) 2010-2017 Barend Gehrels, Amsterdam, the Netherlands.
+// Copyright (c) 2010-2025 Barend Gehrels, Amsterdam, the Netherlands.
 
 // This file was modified by Oracle on 2022.
 // Modifications copyright (c) 2022, Oracle and/or its affiliates.
@@ -11,8 +11,11 @@
 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-//#define BOOST_GEOMETRY_DEBUG_ENRICH
-//#define BOOST_GEOMETRY_DEBUG_SEGMENT_IDENTIFIER
+
+#if defined(TEST_WITH_GEOJSON)
+#define BOOST_GEOMETRY_DEBUG_SEGMENT_IDENTIFIER
+#define BOOST_GEOMETRY_DEBUG_IDENTIFIER
+#endif
 
 #include <geometry_test_common.hpp>
 
@@ -33,18 +36,10 @@
 #include <boost/geometry/strategies/strategies.hpp>
 
 #include <boost/geometry/io/wkt/wkt.hpp>
-#include <boost/geometry/multi/io/wkt/wkt.hpp>
-
-#include <boost/geometry/multi/algorithms/for_each.hpp>
 
-#include <boost/geometry/multi/geometries/multi_linestring.hpp>
-#include <boost/geometry/multi/geometries/multi_polygon.hpp>
-
-
-#if defined(TEST_WITH_SVG)
-#  include <boost/geometry/io/svg/svg_mapper.hpp>
-#  include <boost/geometry/io/svg/write_svg_multi.hpp>
-#  include <boost/geometry/algorithms/detail/overlay/debug_turn_info.hpp>
+#if defined(TEST_WITH_GEOJSON)
+#include <boost/geometry/extensions/gis/io/geojson/geojson_writer.hpp>
+#include "dissolve_geojson_visitor.hpp"
 #endif
 
 
@@ -176,135 +171,6 @@ namespace
     std::string const dissolve_ticket10713 = "POLYGON((-0.7189743518829346 4.1308121681213379, 0.0831791982054710 4.1034231185913086, 0.1004156470298767 4.1107301712036133, 0.1044322624802589 4.1026973724365234, 0.0831791982054710 4.1034231185913086, -0.7711903452873230 3.7412264347076416, -0.7189743518829346 4.1308121681213379))";
 }
 
-
-#if defined(TEST_WITH_SVG)
-template <typename Mapper>
-struct map_visitor
-{
-    map_visitor(Mapper& mapper)
-        : m_mapper(mapper)
-    {}
-
-    template <typename Turns>
-    void visit_turns(int phase, Turns const& turns)
-    {
-        typedef typename boost::range_value<Turns>::type turn_type;
-        std::size_t index = 0;
-        for (turn_type const& turn : turns)
-        {
-            switch (phase)
-            {
-                case 2 : // after self_turns and enrich
-                    if (turn.discarded)
-                    {
-                        m_mapper.map(turn.point, "fill:rgb(255,128,0);", 2);
-                    }
-                    else
-                    {
-                        m_mapper.map(turn.point, "fill:rgb(255,128,0);"
-                                "stroke:rgb(0,0,0);stroke-width:1", 4);
-                    }
-                    break;
-                case 3 : // after enrich/traverse
-                    label_turn(index, turn, -2, "fill:rgb(0,0,128);");
-                    break;
-            }
-            index++;
-        }
-    }
-
-    template <typename Clusters, typename Turns>
-    void visit_clusters(Clusters const& , Turns const& ) {}
-
-    template <typename Turns, typename Turn, typename Operation>
-    void visit_traverse(Turns const& , Turn const& , Operation const& , char const*)
-    {}
-
-    template <typename Turns, typename Turn, typename Operation>
-    void visit_traverse_reject(Turns const& , Turn const& , Operation const& ,
-                               bg::detail::overlay::traverse_error_type )
-    {}
-
-    template <typename Rings>
-    void visit_generated_rings(Rings const& rings)
-    {
-        typedef typename boost::range_value<Rings>::type ring_type;
-        for (ring_type const& ring : rings)
-        {
-            double const area = bg::area(ring);
-            std::string const color = area < 0 ? "rgb(255,0,0)" : "rgb(0,0,255)";
-            std::string const style = "stroke:" + color
-                    + ";stroke-width:0.1;fill-opacity:0.1;fill:" + color;
-            m_mapper.map(ring, style);
-        }
-    }
-
-
-private :
-
-    template <typename Turn>
-    bool label_operation(Turn const& turn, std::size_t index, std::ostream& os)
-    {
-        os << bg::operation_char(turn.operations[index].operation);
-        bool result = false;
-        if (! turn.discarded)
-        {
-            os << "->" << turn.operations[index].enriched.get_next_turn_index();
-            result = true;
-        }
-        if (turn.operations[index].enriched.prefer_start)
-        {
-            os << "$";
-        }
-        if (! turn.operations[index].enriched.startable)
-        {
-            os << "@";
-        }
-
-        return result;
-    }
-
-    template <typename Turn>
-    void label_turn(std::size_t index, Turn const& turn, int y_offset, std::string const& color)
-    {
-        std::ostringstream out;
-        out << index;
-        if (turn.cluster_id != -1)
-        {
-            out << " c=" << turn.cluster_id << " ";
-        }
-        bool lab1 = label_operation(turn, 0, out);
-        out << " / ";
-        bool lab2 = label_operation(turn, 1, out);
-        if (turn.discarded)
-        {
-            out << "!";
-        }
-
-        std::string font8 = "font-family:Arial;font-size:6px";
-        std::string font6 = "font-family:Arial;font-size:4px";
-        std::string style =  color + ";" + font8;
-        if (turn.discarded)
-        {
-            style =  "fill:rgb(92,92,92);" + font6;
-        }
-        else if (turn.cluster_id != -1)
-        {
-            style =  color + ";" + font8;
-        }
-        else if (! lab1 || ! lab2)
-        {
-            style =  color + ";" + font6;
-        }
-
-        m_mapper.text(turn.point, out.str(), style, 5, y_offset, 6);
-    }
-
-    Mapper& m_mapper;
-};
-
-#endif
-
 //! Unittest settings
 struct ut_settings
 {
@@ -334,6 +200,17 @@ void test_dissolve(std::string const& caseid, Geometry const& geometry,
         std::size_t expected_point_count,
         ut_settings const& settings)
 {
+#if defined(TEST_WITH_GEOJSON)
+    std::ostringstream filename;
+    // For QGis, it is usually convenient to always write to the same geojson file.
+    filename << "/tmp/"
+        // << caseid << "_"
+        << "dissolve.geojson";
+    std::ofstream geojson_file(filename.str().c_str());
+
+    boost::geometry::geojson_writer writer(geojson_file);
+#endif    
+
     using coordinate_type = typename bg::coordinate_type<Geometry>::type;
 
     static const bool is_line = bg::geometry_id<GeometryOut>::type::value == 2;
@@ -350,59 +227,21 @@ void test_dissolve(std::string const& caseid, Geometry const& geometry,
                 Geometry, Geometry
             >::type;
 
-        using rescale_policy_type = typename bg::rescale_policy_type
-            <
-                typename bg::point_type<Geometry>::type
-            >::type;
-
-        rescale_policy_type robust_policy
-                = bg::get_rescale_policy<rescale_policy_type>(geometry);
-
-        // This will optionally also create SVG with turn-debug information
         strategy_type strategy;
 
-
-#if ! defined(TEST_WITH_SVG)
-        bg::detail::overlay::overlay_null_visitor visitor;
+#if defined(TEST_WITH_GEOJSON)
+        geojson_visitor visitor(writer);
 #else
-        std::ostringstream filename;
-        filename << "dissolve_" << caseid << "_"
-            << string_from_type<coordinate_type>::name()
-            << ".svg";
-
-        std::ofstream svg(filename.str().c_str());
-
-        using mapper_type = bg::svg_mapper
-            <
-                typename bg::point_type<Geometry>::type
-            >;
-
-        mapper_type mapper(svg, 500, 500);
-        mapper.add(geometry);
-
-        mapper.map(geometry, "fill-opacity:0.5;fill:rgb(153,204,0);"
-            "stroke:rgb(153,204,0);stroke-width:2;fill-rule:nonzero;");
-
-        map_visitor<mapper_type> visitor(mapper);
-#endif
+        bg::detail::overlay::overlay_null_visitor visitor;
+#endif        
 
         bg::dispatch::dissolve
             <
                 Geometry,
                 GeometryOut,
                 false
-            >::apply(geometry, robust_policy, std::back_inserter(dissolved1),
+            >::apply(geometry, std::back_inserter(dissolved1),
                      strategy, visitor);
-
-#if defined(TEST_WITH_SVG)
-        for (GeometryOut& dissolved : dissolved1)
-        {
-           mapper.map(dissolved, "fill-opacity:0.1;fill:rgb(255,0,0);"
-                      "stroke-opacity:0.4;stroke:rgb(255,0,255);stroke-width:3;"
-                                 "fill-rule:nonzero;");
-        }
-#endif
-
     }
 
     if (settings.test_validity)
@@ -482,8 +321,19 @@ void test_dissolve(std::string const& caseid, Geometry const& geometry,
             BOOST_CHECK_MESSAGE(wkt1 == wkt3, caseid << " : output differs: " << wkt1 << " VERSUS " << wkt3);
         }
     }
-}
 
+#if defined(TEST_WITH_GEOJSON)
+    writer.feature(geometry);
+    writer.add_property("type", "input");
+
+    for (const auto& polygon : dissolved3)
+    {
+        writer.feature(polygon);
+        writer.add_property("type", "dissolved");
+    }
+#endif
+
+}
 
 template <typename Geometry, typename GeometryOut>
 void test_one(std::string caseid, std::string const& wkt,
@@ -505,6 +355,8 @@ void test_one(std::string caseid, std::string const& wkt,
         expected_clip_count, expected_hole_count, expected_point_count,
         settings);
 
+#ifdef BOOST_GEOMETRY_TEST_REVERSE
+
     // Verify if reversed version is indeed identical (it should, because each
     // ring is now corrected within dissolve itself
     bg::reverse(geometry);
@@ -514,6 +366,7 @@ void test_one(std::string caseid, std::string const& wkt,
         expected_area,
         expected_clip_count, expected_hole_count, expected_point_count,
         settings);
+#endif        
 
 #ifdef BOOST_GEOMETRY_TEST_MULTI_PERMUTATIONS
     // Test different combinations of a multi-polygon
@@ -652,7 +505,9 @@ void test_all(ut_settings const& settings_for_sensitive_cases)
 
 int test_main(int, char* [])
 {
+#if ! defined(BOOST_GEOMETRY_TEST_ONLY_ONE_TYPE)
     test_all<bg::model::d2::point_xy<float>, true >(ut_settings(0.01));
+#endif    
     test_all<bg::model::d2::point_xy<double>, true >(ut_settings());
     // Counter clockwise input does not work correctly in all cases, it is
     // partly a problem of the test itself