Don't write extent in header for single point and empty geometries

refers to #11

Author: FObermaier

src/NetTopologySuite.IO.GeoPackage/GeoPackageGeoWriter.cs

@@ -68,25 +68,9 @@ public void Write(Geometry geom, Stream stream)
             using (var writer = new BinaryWriter(stream))
             {
                 int byteOrder = (int)ByteOrder.LittleEndian;
-                int ordinates = 0;
-                switch (HandleOrdinates)
-                {
-                    case Ordinates.None:
-                        ordinates = 0;
-                        break;
-                    case Ordinates.XY:
-                        ordinates = 1;
-                        break;
-                    case Ordinates.XYZ:
-                        ordinates = 2;
-                        break;
-                    case Ordinates.XYM:
-                        ordinates = 3;
-                        break;
-                    case Ordinates.XYZM:
-                        ordinates = 4;
-                        break;
-                }
+                
+                int ordinates = GetExtentOrdinates(geom);
+
                 int isEmpty = geom.IsEmpty ? 1 : 0;
                 byte flags = (byte)(byteOrder + (ordinates << 1) + (isEmpty << 4));
                 var header = new GeoPackageBinaryHeader
@@ -117,12 +101,32 @@ public void Write(Geometry geom, Stream stream)
                 }
 
                 // NOTE: GeoPackage handles SRID in its own header.  It would be invalid here.
-                const bool dontHandleSRID = false;
-                var wkbWriter = new WKBWriter(ByteOrder.LittleEndian, dontHandleSRID, emitZ, emitM);
+                const bool handleSRID = false;
+                var wkbWriter = new WKBWriter(ByteOrder.LittleEndian, handleSRID, emitZ, emitM);
                 wkbWriter.Write(geom, stream);
             }
         }
 
+        private int GetExtentOrdinates(Geometry geom)
+        {
+            if (geom.IsEmpty || geom.OgcGeometryType == OgcGeometryType.Point)
+                return 0;
+
+            switch (HandleOrdinates)
+            {
+                case Ordinates.XY:
+                    return 1;
+                case Ordinates.XYZ:
+                    return 2;
+                case Ordinates.XYM:
+                    return 3;
+                case Ordinates.XYZM:
+                    return 4;
+            }
+
+            return 0;
+        }
+        
         /// <summary>
         /// Serializes a given <see cref="Geometry"/> to a new byte array.
         /// </summary>

test/NetTopologySuite.IO.SpatiaLite.Test/Issue11.cs

@@ -0,0 +1,39 @@
+using NetTopologySuite;
+using NetTopologySuite.Geometries;
+using NetTopologySuite.IO;
+using NUnit.Framework;
+
+namespace NetTopologySuite.IO.SpatiaLite.Test;
+
+class Issue11 
+{
+        [TestCase("POINT EMPTY", 17)]
+        [TestCase("POINT(10 10)", 1)]
+        [TestCase("POINT Z(10 10 1)", 1)]
+        [TestCase("POINT M(10 10 2)", 1)]
+        [TestCase("POINT ZM(10 10 1 2)", 1)]
+        [TestCase("POINT(10 10)", 1)]
+        [TestCase("LINESTRING EMPTY", 17)]
+        [TestCase("LINESTRING(10 10, 10 20)", 3)]
+        [TestCase("LINESTRING Z(10 10 1, 10 20 1)", 3)]
+        [TestCase("LINESTRING M(10 10 2, 10 20 2)", 3)]
+        [TestCase("LINESTRING ZM(10 10 1 2, 10 20 1 2)", 3)]
+        public void TestHeaderFlags(string wkt, byte expectedFlags) 
+        {
+            var factory = NtsGeometryServices.Instance.CreateGeometryFactory();
+            var wktReader = new WKTReader() { IsOldNtsCoordinateSyntaxAllowed = false };
+            var geom = wktReader.Read(wkt);
+            var writer = new GeoPackageGeoWriter
+            {
+                HandleOrdinates = Ordinates.None
+            };
+            byte[] s = writer.Write(geom);
+            
+            Assert.That(s[3], Is.EqualTo(expectedFlags));
+
+            var reader = new GeoPackageGeoReader(factory.CoordinateSequenceFactory, factory.PrecisionModel);
+            var dgeom = reader.Read(s);
+            Assert.That(dgeom, Is.EqualTo(geom));
+        }
+
+}

test/NetTopologySuite.IO.SpatiaLite.Test/NetTopologySuite.IO.SpatiaLite.Test.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net8</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>