Merge pull request #1742 from joto/geom-functions

Geom functions

Author: lonvia

src/geom-functions.cpp

@@ -309,22 +309,28 @@ static void split_linestring(linestring_t const &line, double split_at,
     }
 }
 
-geometry_t segmentize(geometry_t const &geom, double max_segment_length)
+void segmentize(geometry_t *output, geometry_t const &input,
+                double max_segment_length)
 {
-    geometry_t output{multilinestring_t{}, geom.srid()};
-    auto *multilinestring = &output.get<multilinestring_t>();
+    output->set_srid(input.srid());
+    auto *multilinestring = &output->set<multilinestring_t>();
 
-    if (geom.is_linestring()) {
-        split_linestring(geom.get<linestring_t>(), max_segment_length,
+    if (input.is_linestring()) {
+        split_linestring(input.get<linestring_t>(), max_segment_length,
                          multilinestring);
-    } else if (geom.is_multilinestring()) {
-        for (auto const &line : geom.get<multilinestring_t>()) {
+    } else if (input.is_multilinestring()) {
+        for (auto const &line : input.get<multilinestring_t>()) {
             split_linestring(line, max_segment_length, multilinestring);
         }
     } else {
-        output.reset();
+        output->reset();
     }
+}
 
+geometry_t segmentize(geometry_t const &input, double max_segment_length)
+{
+    geometry_t output;
+    segmentize(&output, input, max_segment_length);
     return output;
 }
 
@@ -440,16 +446,16 @@ static void add_nodes_to_linestring(linestring_t *linestring, ITERATOR it,
     }
 }
 
-geometry_t line_merge(geometry_t geom)
+void line_merge(geometry_t *output, geometry_t const &input)
 {
-    geometry_t output{multilinestring_t{}, geom.srid()};
-
-    if (geom.is_null()) {
-        output.reset();
-        return output;
+    if (!input.is_multilinestring()) {
+        output->reset();
+        return;
     }
 
-    assert(geom.is_multilinestring());
+    output->set_srid(input.srid());
+
+    auto &linestrings = output->set<multilinestring_t>();
 
     // Make a list of all endpoints...
     struct endpoint_t
@@ -484,16 +490,16 @@ geometry_t line_merge(geometry_t geom)
     struct connection_t
     {
         std::size_t left = NOCONN;
-        geom::linestring_t const *ls;
+        linestring_t const *ls;
         std::size_t right = NOCONN;
 
-        explicit connection_t(geom::linestring_t const *l) noexcept : ls(l) {}
+        explicit connection_t(linestring_t const *l) noexcept : ls(l) {}
     };
 
     std::vector<connection_t> conns;
 
     // Initialize the two lists.
-    for (auto const &line : geom.get<multilinestring_t>()) {
+    for (auto const &line : input.get<multilinestring_t>()) {
         endpoints.emplace_back(line.front(), conns.size(), true);
         endpoints.emplace_back(line.back(), conns.size(), false);
         conns.emplace_back(&line);
@@ -519,8 +525,6 @@ geometry_t line_merge(geometry_t geom)
         }
     }
 
-    auto &linestrings = output.get<multilinestring_t>();
-
     // First find all open ends and use them as starting points to assemble
     // linestrings. Mark ways as "done" as we go.
     std::size_t done_ways = 0;
@@ -608,9 +612,14 @@ geometry_t line_merge(geometry_t geom)
     }
 
     if (linestrings.num_geometries() == 0) {
-        output.reset();
+        output->reset();
     }
+}
 
+geometry_t line_merge(geometry_t const &input)
+{
+    geometry_t output;
+    line_merge(&output, input);
     return output;
 }
 

src/geom-functions.hpp

@@ -115,13 +115,27 @@ geometry_t transform(geometry_t const &input, reprojection const &reprojection);
  * Returns a modified geometry having no segment longer than the given
  * max_segment_length.
  *
- * \param geom The input geometry, must be a linestring or multilinestring.
+ * \param output Pointer to output geometry. Will be a multilinestring
+ *        geometry, or nullgeom_t on error.
+ * \param input The input geometry, must be a linestring or multilinestring.
  * \param max_segment_length The maximum length (using Euclidean distance
- *        in the length unit of the srs of the geometry) of each resulting
+ *        in the length unit of the SRS of the geometry) of each resulting
+ *        linestring.
+ */
+void segmentize(geometry_t *output, geometry_t const &input,
+                double max_segment_length);
+
+/**
+ * Returns a modified geometry having no segment longer than the given
+ * max_segment_length.
+ *
+ * \param input The input geometry, must be a linestring or multilinestring.
+ * \param max_segment_length The maximum length (using Euclidean distance
+ *        in the length unit of the SRS of the geometry) of each resulting
  *        linestring.
  * \returns Resulting multilinestring geometry, nullgeom_t on error.
  */
-geometry_t segmentize(geometry_t const &geom, double max_segment_length);
+geometry_t segmentize(geometry_t const &input, double max_segment_length);
 
 /**
  * Calculate area of geometry.
@@ -149,10 +163,20 @@ std::vector<geometry_t> split_multi(geometry_t &&geom, bool split_multi = true);
  * returns a multilinestring unless there is an error or the input geometry
  * is a nullgeom_t, in which case nullgeom_t is returned.
  *
- * \param geom Input geometry.
+ * \param output Pointer to output geometry.
+ * \param input Input geometry.
+ */
+void line_merge(geometry_t *output, geometry_t const &input);
+
+/**
+ * Merge lines in a multilinestring end-to-end as far as possible. Always
+ * returns a multilinestring unless there is an error or the input geometry
+ * is a nullgeom_t, in which case nullgeom_t is returned.
+ *
+ * \param input Input geometry.
  * \returns Result multilinestring.
  */
-geometry_t line_merge(geometry_t geom);
+geometry_t line_merge(geometry_t const &input);
 
 /**
  * Calculate the centroid of a geometry.