Fix buffer element erosion for negative distance and remove overlay d…

…eps (#1239)

include/geos/operation/buffer/BufferBuilder.h

@@ -56,10 +56,9 @@ class PlanarGraph;
 namespace operation {
 namespace buffer {
 class BufferSubgraph;
-}
-namespace overlay {
 class PolygonBuilder;
 }
+
 }
 }
 
@@ -233,7 +232,7 @@ class GEOS_DLL BufferBuilder {
      *        the final polygons
      */
     void buildSubgraphs(const std::vector<BufferSubgraph*>& subgraphList,
-                        overlay::PolygonBuilder& polyBuilder);
+                        PolygonBuilder& polyBuilder);
 
     /// \brief
     /// Return the externally-set noding::Noder OR a newly created

include/geos/operation/buffer/BufferNodeFactory.h

@@ -0,0 +1,52 @@
+/**********************************************************************
+ *
+ * GEOS - Geometry Engine Open Source
+ * http://geos.osgeo.org
+ *
+ * Copyright (C) 2006 Refractions Research Inc.
+ *
+ * This is free software; you can redistribute and/or modify it under
+ * the terms of the GNU Lesser General Public Licence as published
+ * by the Free Software Foundation.
+ * See the COPYING file for more information.
+ *
+ **********************************************************************/
+
+#pragma once
+
+#include <geos/export.h>
+
+#include <vector>
+
+#include <geos/geomgraph/NodeFactory.h> // for inheritance
+
+// Forward declarations
+namespace geos {
+namespace geom {
+class Coordinate;
+}
+namespace geomgraph {
+class Node;
+}
+}
+
+namespace geos {
+namespace operation { // geos::operation
+namespace buffer { // geos::operation::buffer
+
+/** \brief
+ * Creates nodes for use in the geomgraph::PlanarGraph constructed during
+ * buffer operations. NOTE: also used by operation::valid
+ */
+class GEOS_DLL BufferNodeFactory: public geomgraph::NodeFactory {
+public:
+    BufferNodeFactory(): geomgraph::NodeFactory() {}
+    geomgraph::Node* createNode(const geom::Coordinate& coord) const override;
+    static const geomgraph::NodeFactory& instance();
+};
+
+
+} // namespace geos::operation::buffer
+} // namespace geos::operation
+} // namespace geos
+

include/geos/operation/buffer/MaximalEdgeRing.h

@@ -0,0 +1,104 @@
+/**********************************************************************
+ *
+ * GEOS - Geometry Engine Open Source
+ * http://geos.osgeo.org
+ *
+ * Copyright (C) 2006 Refractions Research Inc.
+ *
+ * This is free software; you can redistribute and/or modify it under
+ * the terms of the GNU Lesser General Public Licence as published
+ * by the Free Software Foundation.
+ * See the COPYING file for more information.
+ *
+ **********************************************************************
+ *
+ * Last port: operation/overlay/MaximalEdgeRing.java rev. 1.15 (JTS-1.10)
+ *
+ **********************************************************************/
+
+#pragma once
+
+#include <geos/export.h>
+
+#include <vector>
+
+#include <geos/geomgraph/EdgeRing.h> // for inheritance
+
+// Forward declarations
+namespace geos {
+namespace geom {
+class GeometryFactory;
+}
+namespace geomgraph {
+class DirectedEdge;
+}
+namespace operation {
+namespace buffer {
+class MinimalEdgeRing;
+}
+}
+}
+
+namespace geos {
+namespace operation { // geos::operation
+namespace buffer { // geos::operation::buffer
+
+/** \brief
+ * A ring of [DirectedEdges](@ref geomgraph::DirectedEdge) which may contain nodes of degree > 2.
+ *
+ * A MaximalEdgeRing may represent two different spatial entities:
+ *
+ * - a single polygon possibly containing inversions (if the ring is oriented CW)
+ * - a single hole possibly containing exversions (if the ring is oriented CCW)
+ *
+ * If the MaximalEdgeRing represents a polygon,
+ * the interior of the polygon is strongly connected.
+ *
+ * These are the form of rings used to define polygons under some spatial data models.
+ * However, under the OGC SFS model, [MinimalEdgeRings](@ref MinimalEdgeRing) are required.
+ * A MaximalEdgeRing can be converted to a list of MinimalEdgeRings using the
+ * {@link #buildMinimalRings() } method.
+ *
+ * @see com.vividsolutions.jts.operation.overlay.MinimalEdgeRing
+ */
+class GEOS_DLL MaximalEdgeRing: public geomgraph::EdgeRing {
+
+public:
+
+    MaximalEdgeRing(geomgraph::DirectedEdge* start,
+                    const geom::GeometryFactory* geometryFactory);
+    // throw(const TopologyException &)
+
+    ~MaximalEdgeRing() override = default;
+
+    geomgraph::DirectedEdge* getNext(geomgraph::DirectedEdge* de) override;
+
+    void setEdgeRing(geomgraph::DirectedEdge* de, geomgraph::EdgeRing* er) override;
+
+    /// \brief
+    /// This function returns a newly allocated vector of
+    /// pointers to newly allocated MinimalEdgeRing objects.
+    ///
+    /// @deprecated pass the vector yourself instead
+    ///
+    std::vector<MinimalEdgeRing*>* buildMinimalRings();
+
+    /// \brief
+    /// This function pushes pointers to newly allocated  MinimalEdgeRing
+    /// objects to the provided vector.
+    ///
+    void buildMinimalRings(std::vector<MinimalEdgeRing*>& minEdgeRings);
+    void buildMinimalRings(std::vector<EdgeRing*>& minEdgeRings);
+
+    /// \brief
+    /// For all nodes in this EdgeRing,
+    /// link the DirectedEdges at the node to form minimalEdgeRings
+    ///
+    void linkDirectedEdgesForMinimalEdgeRings();
+};
+
+
+} // namespace geos::operation::buffer
+} // namespace geos::operation
+} // namespace geos
+

include/geos/operation/buffer/MinimalEdgeRing.h

@@ -0,0 +1,80 @@
+/**********************************************************************
+ *
+ * GEOS - Geometry Engine Open Source
+ * http://geos.osgeo.org
+ *
+ * Copyright (C) 2006 Refractions Research Inc.
+ *
+ * This is free software; you can redistribute and/or modify it under
+ * the terms of the GNU Lesser General Public Licence as published
+ * by the Free Software Foundation.
+ * See the COPYING file for more information.
+ *
+ **********************************************************************
+ *
+ * Last port: operation/overlay/MinimalEdgeRing.java rev. 1.13 (JTS-1.10)
+ *
+ **********************************************************************/
+
+#pragma once
+
+
+#include <geos/export.h>
+
+#include <geos/geomgraph/EdgeRing.h> // for inheritance
+#include <geos/geomgraph/DirectedEdge.h> // for inlines
+
+#include <vector>
+
+// Forward declarations
+namespace geos {
+namespace geom {
+class GeometryFactory;
+}
+namespace geomgraph {
+class DirectedEdge;
+class EdgeRing;
+}
+}
+
+namespace geos {
+namespace operation { // geos::operation
+namespace buffer { // geos::operation::buffer
+
+/** \brief
+ * A ring of [Edges](@ref geomgraph::Edge) with the property that no node
+ * has degree greater than 2.
+ *
+ * These are the form of rings required to represent polygons
+ * under the OGC SFS spatial data model.
+ *
+ * @see operation::buffer::MaximalEdgeRing
+ *
+ */
+class GEOS_DLL MinimalEdgeRing: public geomgraph::EdgeRing {
+
+public:
+
+    MinimalEdgeRing(geomgraph::DirectedEdge* start,
+                    const geom::GeometryFactory* geometryFactory);
+
+    ~MinimalEdgeRing() override {};
+
+    geomgraph::DirectedEdge* getNext(geomgraph::DirectedEdge* de) override
+    {
+        return de->getNextMin();
+    };
+
+    void setEdgeRing(geomgraph::DirectedEdge* de,
+                     geomgraph::EdgeRing* er) override
+    {
+        de->setMinEdgeRing(er);
+    };
+
+};
+
+
+} // namespace geos::operation::buffer
+} // namespace geos::operation
+} // namespace geos
+