Fix exception in WKB export for polygon with first ring of zero area (#276)

Author: stolstov

src/main/java/com/esri/core/geometry/MultiPathImpl.java

@@ -2133,27 +2133,34 @@ int getOGCPolygonCount() {
 	protected void _updateOGCFlags() {
 		if (_hasDirtyFlag(DirtyFlags.DirtyOGCFlags)) {
 			_updateRingAreas2D();
-
-			int pathCount = getPathCount();
-			if (pathCount > 0 && (m_pathFlags == null || m_pathFlags.size() < pathCount))
-				m_pathFlags = (AttributeStreamOfInt8) AttributeStreamBase
-						.createByteStream(pathCount + 1);
-
-			int firstSign = 1;
-			for (int ipath = 0; ipath < pathCount; ipath++) {
-				double area = m_cachedRingAreas2D.read(ipath);
-				if (ipath == 0)
-					firstSign = area > 0 ? 1 : -1;
-				if (area * firstSign > 0.0)
-					m_pathFlags.setBits(ipath,
-							(byte) PathFlags.enumOGCStartPolygon);
-				else
-					m_pathFlags.clearBits(ipath,
-							(byte) PathFlags.enumOGCStartPolygon);
-			}
+			_updateOGCFlagsHelper();
 			_setDirtyFlag(DirtyFlags.DirtyOGCFlags, false);
 		}
 	}
+	
+	private void _updateOGCFlagsHelper() {
+		int pathCount = getPathCount();
+		if (pathCount > 0 && (m_pathFlags == null || m_pathFlags.size() < pathCount))
+			m_pathFlags = (AttributeStreamOfInt8) AttributeStreamBase.createByteStream(pathCount + 1);
+
+		// firstSign is the sign of first ring.
+		// a first ring with non zero area defines the
+		// value. First zero area rings are written out as enumOGCStartPolygon.
+		int firstSign = 0;
+		for (int ipath = 0; ipath < pathCount; ipath++) {
+			double area = m_cachedRingAreas2D.read(ipath);
+			if (firstSign == 0) {
+				// if the first ring is inverted we assume that the
+				// whole polygon is inverted.
+				firstSign = MathUtils.sign(area);
+			}
+
+			if (area * firstSign > 0.0 || firstSign == 0)
+				m_pathFlags.setBits(ipath, (byte) PathFlags.enumOGCStartPolygon);
+			else
+				m_pathFlags.clearBits(ipath, (byte) PathFlags.enumOGCStartPolygon);
+		}
+	}
 
 	public int getPathIndexFromPointIndex(int pointIndex) {
 		int positionHint = m_currentPathIndex;// in case of multithreading

src/test/java/com/esri/core/geometry/TestImportExport.java

@@ -44,15 +44,6 @@ protected void tearDown() throws Exception {
 
 	@Test
 	public static void testImportExportShapePolygon() {
-//		{
-//			String s = "MULTIPOLYGON (((-1.4337158203098852 53.42590083930004, -1.4346462383651897 53.42590083930004, -1.4349713164114632 53.42426406667512, -1.4344808816770183 53.42391134176576, -1.4337158203098852 53.424339319373516, -1.4337158203098852 53.42590083930004, -1.4282226562499147 53.42590083930004, -1.4282226562499147 53.42262754610009, -1.423659941537096 53.42262754610009, -1.4227294921872726 53.42418897437618, -1.4199829101572732 53.42265258737483, -1.4172363281222147 53.42418897437334, -1.4144897460898278 53.42265258737625, -1.4144897460898278 53.42099079900008, -1.4117431640598568 53.42099079712516, -1.4117431640598568 53.41849780932388, -1.4112778948070286 53.41771711805022, -1.4114404909237805 53.41689867267529, -1.411277890108579 53.416080187950215, -1.4117431640598568 53.4152995338453, -1.4117431657531654 53.40953184824072, -1.41723632610001 53.40953184402311, -1.4172363281199125 53.406257299700044, -1.4227294921899158 53.406257299700044, -1.4227294921899158 53.40789459668797, -1.4254760767598498 53.40789460061099, -1.4262193642339867 53.40914148401417, -1.4273828468095076 53.409531853100034, -1.4337158203098852 53.409531790075235, -1.4337158203098852 53.41280609140024, -1.4392089843723568 53.41280609140024, -1.439208984371362 53.41608014067522, -1.441160015802268 53.41935368587538, -1.4427511170075604 53.41935368587538, -1.4447021484373863 53.42099064750012, -1.4501953124999432 53.42099064750012, -1.4501953124999432 53.43214683850347, -1.4513643355446106 53.434108816701794, -1.4502702625278232 53.43636597733034, -1.4494587195580948 53.437354845300334, -1.4431075935937656 53.437354845300334, -1.4372459179209045 53.43244635455021, -1.433996276212838 53.42917388040006, -1.4337158203098852 53.42917388040006, -1.4337158203098852 53.42590083930004)))";
-//			Geometry g = OperatorImportFromWkt.local().execute(0,  Geometry.Type.Unknown, s, null);
-//			boolean result1 = OperatorSimplify.local().isSimpleAsFeature(g, null, null);
-//			boolean result2 = OperatorSimplifyOGC.local().isSimpleOGC(g, null, true, null, null);
-//			Geometry simple = OperatorSimplifyOGC.local().execute(g, null, true, null);
-//			OperatorFactoryLocal.saveToWKTFileDbg("c:/temp/simplifiedeeee",  simple, null);
-//			int i = 0;
-//		}
 		OperatorExportToESRIShape exporterShape = (OperatorExportToESRIShape) OperatorFactoryLocal.getInstance().getOperator(Operator.Type.ExportToESRIShape);
 		OperatorImportFromESRIShape importerShape = (OperatorImportFromESRIShape) OperatorFactoryLocal.getInstance().getOperator(Operator.Type.ImportFromESRIShape);
 
@@ -1754,6 +1745,20 @@ public static void testImportGeoJsonSpatialReference() throws Exception {
 		assertTrue(mapGeometry4326.getGeometry().equals(mapGeometry3857.getGeometry()));
 	}
 
+	@Test
+	public void testZeroRingWkb() {
+		//https://github.com/Esri/geometry-api-java/issues/275
+		Polygon poly = new Polygon();
+		poly.startPath(0, 0);
+		poly.lineTo(0, 10);
+		poly.lineTo(0, 10);
+		poly.addEnvelope(new Envelope(1, 1, 3, 3), false);
+		
+		ByteBuffer bb = OperatorExportToWkb.local().execute(0, poly, null);
+		Geometry res = OperatorImportFromWkb.local().execute(0, Geometry.Type.Unknown, bb, null);
+		assertTrue(res.equals(poly));
+	}
+	
 	public static Polygon makePolygon() {
 		Polygon poly = new Polygon();
 		poly.startPath(0, 0);