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Add support for 4-dimensional coordinates to GeoJSON4STJ #139

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Add support for 4-dimensional coordinates to GeoJSON4STJ #139

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89 changes: 62 additions & 27 deletions src/NetTopologySuite.IO.GeoJSON4STJ/Converters/StjParsedCoordinates.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -191,15 +191,21 @@ public MultiPolygon ToMultiPolygon(GeometryFactory factory)

private static Point ParsePoint(ref Utf8JsonReader reader, GeometryFactory factory)
{
var (x, y, zOrNull) = ReadXYZ(ref reader, factory.PrecisionModel);
var (x, y, zOrNull, mOrNull) = ReadXYZM(ref reader, factory.PrecisionModel);

var seq = factory.CoordinateSequenceFactory.Create(1, zOrNull.HasValue ? 3 : 2, 0);
int dimension = mOrNull.HasValue ? 4 : zOrNull.HasValue ? 3 : 2;
int measures = mOrNull.HasValue ? 1 : 0;
var seq = factory.CoordinateSequenceFactory.Create(1, dimension, measures);
seq.SetX(0, x);
seq.SetY(0, y);
if (zOrNull is double z)
{
seq.SetZ(0, z);
}
if (mOrNull is double m)
{
seq.SetM(0, m);
}

return factory.CreatePoint(seq);
}
Expand All @@ -208,10 +214,11 @@ private static CoordinateSequence ParseCoordinateSequence(ref Utf8JsonReader rea
{
ords = ords ?? new List<double>();
bool sequenceHasZ = false;
bool sequenceHasM = false;

// read the first coordinate to kick things off...
{
var (x, y, zOrNull) = ReadXYZ(ref reader, factory.PrecisionModel);
var (x, y, zOrNull, mOrNull) = ReadXYZM(ref reader, factory.PrecisionModel);

ords.Add(x);
ords.Add(y);
Expand All @@ -220,8 +227,13 @@ private static CoordinateSequence ParseCoordinateSequence(ref Utf8JsonReader rea
ords.Add(z);
sequenceHasZ = true;
}
if (mOrNull is double m)
{
ords.Add(m);
sequenceHasM = true;
}

Debug.Assert(reader.TokenType == JsonTokenType.EndArray, "ReadXYZ was supposed to leave us at the EndArray token just past the last ordinate value");
Debug.Assert(reader.TokenType == JsonTokenType.EndArray, "ReadXYZM was supposed to leave us at the EndArray token just past the last ordinate value");
reader.ReadOrThrow();
}

Expand All @@ -230,32 +242,46 @@ private static CoordinateSequence ParseCoordinateSequence(ref Utf8JsonReader rea
reader.ReadOrThrow();

reader.AssertToken(JsonTokenType.Number);
var (x, y, zOrNull) = ReadXYZ(ref reader, factory.PrecisionModel);
var (x, y, zOrNull, mOrNull) = ReadXYZM(ref reader, factory.PrecisionModel);

if (!sequenceHasZ && zOrNull.HasValue)
{
// we've been reading XY up to this point, but we just saw an XYZ. take a short
// one-time detour to weave dummy Z values into what we've already read so far,
// then continue reading the rest of the values.
ords = ConvertXYToXYZ(ords);
ords = ConvertOrdsToNewDimension(ords, 3);
sequenceHasZ = true;
}

if (!sequenceHasM && mOrNull.HasValue)
{
// we've been reading XYZ up to this point, but we just saw an XYZM. take a short
// one-time detour to weave dummy M values into what we've already read so far,
// then continue reading the rest of the values.
ords = ConvertOrdsToNewDimension(ords, 4);
sequenceHasM = true;
}

ords.Add(x);
ords.Add(y);
if (sequenceHasZ)
{
ords.Add(zOrNull ?? Coordinate.NullOrdinate);
}
if (sequenceHasM)
{
ords.Add(mOrNull ?? Coordinate.NullOrdinate);
}

Debug.Assert(reader.TokenType == JsonTokenType.EndArray, "ReadXYZ was supposed to leave us at the EndArray token just past the last ordinate value");
Debug.Assert(reader.TokenType == JsonTokenType.EndArray, "ReadXYZM was supposed to leave us at the EndArray token just past the last ordinate value");
reader.ReadOrThrow();
}

reader.AssertToken(JsonTokenType.EndArray);

int dimension = sequenceHasZ ? 3 : 2;
var seq = factory.CoordinateSequenceFactory.Create(ords.Count / dimension, dimension, 0);
int dimension = sequenceHasM ? 4 : sequenceHasZ ? 3 : 2;
int measures = sequenceHasM ? 1 : 0;
var seq = factory.CoordinateSequenceFactory.Create(ords.Count / dimension, dimension, measures);
int ordIndex = 0;
for (int coordIndex = 0; coordIndex < seq.Count; coordIndex++)
{
Expand All @@ -265,6 +291,10 @@ private static CoordinateSequence ParseCoordinateSequence(ref Utf8JsonReader rea
{
seq.SetZ(coordIndex, ords[ordIndex++]);
}
if (sequenceHasM)
{
seq.SetM(coordIndex, ords[ordIndex++]);
}
}

return seq;
Expand Down Expand Up @@ -326,9 +356,9 @@ private static MultiPolygon ParseMultiPolygon(ref Utf8JsonReader reader, Geometr
return factory.CreateMultiPolygon(polygons.ToArray());
}

private static (double x, double y, double? zOrNull) ReadXYZ(ref Utf8JsonReader reader, PrecisionModel precisionModel)
private static (double x, double y, double? zOrNull, double? mOrNull) ReadXYZM(ref Utf8JsonReader reader, PrecisionModel precisionModel)
{
Debug.Assert(reader.TokenType == JsonTokenType.Number, "ReadXYZ was supposed to be called with a reader positioned on the first Number token of the array.");
Debug.Assert(reader.TokenType == JsonTokenType.Number, "ReadXYZM was supposed to be called with a reader positioned on the first Number token of the array.");

// x
double x = precisionModel.MakePrecise(reader.GetDouble());
Expand All @@ -338,21 +368,28 @@ private static (double x, double y, double? zOrNull) ReadXYZ(ref Utf8JsonReader
reader.AssertToken(JsonTokenType.Number);
double y = precisionModel.MakePrecise(reader.GetDouble());

double? z = null;
double? m = null;

// z?
reader.ReadOrThrow();
if (reader.TokenType == JsonTokenType.Number)
{
// yes z
double z = reader.GetDouble();
AdvanceReaderToEndOfCurrentNumberArray(ref reader);
return (x, y, z);
z = reader.GetDouble();
reader.ReadOrThrow();
}
else

// m?
if (reader.TokenType == JsonTokenType.Number)
{
// no z
reader.AssertToken(JsonTokenType.EndArray);
return (x, y, null);
// yes m
m = reader.GetDouble();
reader.ReadOrThrow();
}

AdvanceReaderToEndOfCurrentNumberArray(ref reader);
return (x, y, z, m);
}

private static void AdvanceReaderToEndOfCurrentNumberArray(ref Utf8JsonReader reader)
Expand All @@ -365,20 +402,18 @@ private static void AdvanceReaderToEndOfCurrentNumberArray(ref Utf8JsonReader re
reader.AssertToken(JsonTokenType.EndArray);
}

private static List<double> ConvertXYToXYZ(List<double> xys)
private static List<double> ConvertOrdsToNewDimension(List<double> ords, int dimension)
{
Debug.Assert(xys.Count % 2 == 0, "This was only supposed to be called with XY values.");
Debug.Assert(ords.Count % dimension - 1 == 0, $"This was only supposed to be called with {dimension - 1}-dimensional values.");

var xyzs = new List<double>(xys.Capacity);
int i = 0;
while (i < xys.Count)
var newOrds = new List<double>(ords.Capacity);
for (int i = 0; i < dimension - 1; i++)
{
xyzs.Add(xys[i++]);
xyzs.Add(xys[i++]);
xyzs.Add(Coordinate.NullOrdinate);
newOrds.Add( ords[i] );
}
newOrds.Add(Coordinate.NullOrdinate);

return xyzs;
return newOrds;
}

private static Polygon ToPolygon(IReadOnlyList<CoordinateSequence> ringSequences, GeometryFactory factory)
Expand Down
24 changes: 24 additions & 0 deletions test/NetTopologySuite.IO.GeoJSON4STJ.Test/Converters/GeometryConverterTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,18 @@ public void TestReadPoint3D()
Assert.That(geom.Coordinate, Is.InstanceOf(typeof(CoordinateZ)));
}

[Test]
public void TestReadPoint4D()
{
string geoJson = @"{ ""type"" : ""Point"", ""coordinates"": [102.0, 0.5, 6.2, 0.02] }";
var options = DefaultOptions;
var geom = Deserialize(geoJson, options);

Assert.That(geom != null);
Assert.That(geom, Is.InstanceOf(typeof(Point)));
Assert.That(geom.Coordinate, Is.InstanceOf(typeof(CoordinateZM)));
}

[Test]
public void TestReadLineString2D()
{
Expand All @@ -81,6 +93,18 @@ public void TestReadLineString3D()
Assert.That(geom.Coordinate, Is.InstanceOf(typeof(CoordinateZ)));
}

[Test]
public void TestReadLineString4D()
{
string geoJson = @"{ ""type"" : ""LineString"", ""coordinates"": [[102.0, 0.5, 2.45, 0.02],[112.7, 2.1, 2.34, 0.04]] }";
var options = DefaultOptions;
var geom = Deserialize(geoJson, options);

Assert.That(geom != null);
Assert.That(geom, Is.InstanceOf(typeof(LineString)));
Assert.That(geom.Coordinate, Is.InstanceOf(typeof(CoordinateZM)));
}

[Test]
public void TestReadPolygon2D()
{
Expand Down
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