Add ST_SnapToSelf function

docs/CHANGELOG.md

@@ -6,3 +6,4 @@
 - Do not ask for SRID when geometry is empty
 - Add the name of the table in the FGB header
 - Fix null way id on OSM file
+- Add ST_SnapToSelf function

h2gis-functions/src/main/java/org/h2gis/functions/factory/H2GISFunctions.java

@@ -75,6 +75,7 @@
 import org.h2gis.functions.spatial.properties.*;
 import org.h2gis.functions.spatial.snap.ST_Project;
 import org.h2gis.functions.spatial.snap.ST_Snap;
+import org.h2gis.functions.spatial.snap.ST_SnapToSelf;
 import org.h2gis.functions.spatial.split.ST_LineIntersector;
 import org.h2gis.functions.spatial.split.ST_Split;
 import org.h2gis.functions.spatial.split.ST_SubDivide;
@@ -338,7 +339,8 @@ public static Function[] getBuiltInsFunctions() {
  new ST_Project(),
  new ST_IsProjectedCRS(),
  new ST_IsGeographicCRS(),
- new ST_SnapToGrid()
+ new ST_SnapToGrid(),
+ new ST_SnapToSelf()
  };
  }
 

h2gis-functions/src/main/java/org/h2gis/functions/spatial/snap/ST_SnapToSelf.java

@@ -0,0 +1,74 @@
+/**
+ * H2GIS is a library that brings spatial support to the H2 Database Engine
+ * <a href="https://www.h2database.com">https://www.h2database.com</a>. H2GIS is developed by CNRS
+ * <a href="https://www.cnrs.fr/">https://www.cnrs.fr/</a>.
+ * <p>
+ * This code is part of the H2GIS project. H2GIS 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;
+ * version 3.0 of the License.
+ * <p>
+ * H2GIS 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 <https://www.gnu.org/licenses/>.
+ * <p>
+ * <p>
+ * For more information, please consult: <a href="https://www.h2gis.org/">https://www.h2gis.org/</a>
+ * or contact directly: info_at_h2gis.org
+ */
+
+package org.h2gis.functions.spatial.snap;
+
+import org.h2gis.api.DeterministicScalarFunction;
+import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.operation.overlay.snap.GeometrySnapper;
+
+import java.sql.SQLException;
+
+/**
+ * Snaps a geometry to itself with a given tolerance
+ * Allows optionally cleaning the result to ensure it is topologically valid
+ *
+ * @author Erwan Bocher
+ */
+public class ST_SnapToSelf extends DeterministicScalarFunction {
+
+ public ST_SnapToSelf() {
+ addProperty(PROP_REMARKS, "Snaps a geometry to itself with a given tolerance.\n" +
+ "Allows optionally cleaning the result to ensure it is topologically valid. true by default");
+ }
+
+ @Override
+ public String getJavaStaticMethod() {
+ return "execute";
+ }
+
+
+ /**
+ * Snaps a geometry to itself with a given tolerance
+ *
+ * @param geometryA a geometry to snap
+ * @param distance the tolerance to use
+ * @return the snapped geometries
+ * @throws SQLException
+ */
+ public static Geometry execute(Geometry geometryA, double distance ) throws SQLException {
+ return execute(geometryA, distance, true);
+ }
+ /**
+ * Snaps a geometry to itself with a given tolerance
+ *
+ * @param geometryA a geometry to snap
+ * @param distance the tolerance to use
+ * @param clean true to clean the geometry
+ * @return the snapped geometries
+ * @throws SQLException
+ */
+ public static Geometry execute(Geometry geometryA, double distance, boolean clean ) throws SQLException {
+ if (geometryA == null ) {
+ return null;
+ }
+ return GeometrySnapper.snapToSelf(geometryA, distance, clean);
+ }
+}

h2gis-functions/src/test/java/org/h2gis/functions/spatial/processing/ProcessingFunctionTest.java

@@ -333,6 +333,14 @@ public void test_ST_SnapToGrid2() throws Exception {
  rs.close();
  }
 
+ @Test
+ public void test_ST_SnapToSelf1() throws Exception {
+ ResultSet rs = st.executeQuery("SELECT ST_SnapToSelf('POLYGON ((0 0, 1 1, 2 1, 3 0.5, 2 -3, 3 0.499, 0 0))'::GEOMETRY, 0.001);");
+ rs.next();
+ assertGeometryEquals("POLYGON ((0 0, 1 1, 2 1, 3 0.5, 3 0.499, 0 0))", rs.getBytes(1));
+ rs.close();
+ }
+
 
  @Test
  public void test_ST_RingSideBuffer1() throws Exception {