public static byte[] ToFlatGeobuf(FeatureCollection fc, GeometryType?geometryType = null, byte dimensions = 2, IList <ColumnMeta> columns = null)
{
ulong count = (ulong)fc.Features.LongCount();
if (count == 0)
{
return(new byte[0]);
}
var index = new PackedHilbertRTree(count);
foreach (var f in fc.Features)
{
var b = f.Geometry.EnvelopeInternal;
index.Add(b.MinX, b.MinY, b.MaxX, b.MaxY);
}
index.Finish();
var featureFirst = fc.Features.First();
if (geometryType == null)
{
geometryType = GeometryConversions.ToGeometryType(featureFirst.Geometry);
}
if (columns == null && featureFirst.Attributes != null)
{
columns = featureFirst.Attributes.GetNames()
.Select(n => new ColumnMeta()
{
Name = n, Type = ToColumnType(featureFirst.Attributes.GetType(n))
})
.ToList();
}
using (var memoryStream = new MemoryStream())
{
using (var featuresStream = new MemoryStream())
using (var offsetsStream = new MemoryStream())
using (var offetsWriter = new BinaryWriter(offsetsStream))
{
ulong offset = 0;
for (ulong i = 0; i < count; i++)
{
var feature = fc.Features[(int)index.Indices[i]];
var buffer = FeatureConversions.ToByteBuffer(feature, geometryType.Value, dimensions, columns);
featuresStream.Write(buffer, 0, buffer.Length);
offetsWriter.Write(offset);
offset += (ulong)buffer.Length;
}
var header = BuildHeader(count, geometryType.Value, dimensions, columns, index);
memoryStream.Write(header, 0, header.Length);
var indexBytes = index.ToBytes();
memoryStream.Write(indexBytes, 0, indexBytes.Length);
offsetsStream.WriteTo(memoryStream);
featuresStream.WriteTo(memoryStream);
}
return(memoryStream.ToArray());
}
}
private static IList <LayerMeta> IntrospectLayers(FeatureCollection fc)
{
var featureFirst = fc.Features.First();
IList <ColumnMeta> columns = null;
if (featureFirst.Attributes != null && featureFirst.Attributes.Count > 0)
{
columns = featureFirst.Attributes.GetNames()
.Select(n => new ColumnMeta()
{
Name = n, Type = ToColumnType(featureFirst.Attributes.GetType(n))
})
.ToList();
}
var geometryTypes = fc.Features
.Select(f => GeometryConversions.ToGeometryType(f.Geometry))
.Distinct();
IList <LayerMeta> layers = geometryTypes
.Select(geometryType => new LayerMeta()
{
GeometryType = geometryType, Columns = columns
})
.ToList();
return(layers);
}
public static void Serialize(Stream output, IEnumerable <IFeature> features, GeometryType geometryType, byte dimensions = 2, IList <ColumnMeta> columns = null)
{
output.Write(Constants.MagicBytes);
var header = BuildHeader(0, geometryType, columns, null);
output.Write(header);
foreach (var feature in features)
{
var featureGeometryType = geometryType == GeometryType.Unknown ? GeometryConversions.ToGeometryType(feature.Geometry) : geometryType;
var buffer = FeatureConversions.ToByteBuffer(feature, featureGeometryType, dimensions, columns);
output.Write(buffer);
}
}
public static byte[] ToByteBuffer(IFeature feature, IList <LayerMeta> layers)
{
// TODO: size might not be enough, need to be adaptive
var builder = new FlatBufferBuilder(1024);
// TODO: improve layer introspection
var layer = layers.First(l => l.GeometryType == GeometryConversions.ToGeometryType(feature.Geometry));
var layerIndex = (uint)layers.IndexOf(layer);
var columns = layer.Columns;
var geometryOffset = GeometryConversions.BuildGeometry(builder, feature.Geometry);
VectorOffset?valuesOffset = null;
if (feature.Attributes != null && feature.Attributes.Count > 0 && columns != null)
{
var valueOffsets = new List <Offset <Value> >();
foreach (var column in columns)
{
if (feature.Attributes.Exists(column.Name))
{
ushort columnIndex = (ushort)columns.IndexOf(column);
var value = feature.Attributes[column.Name];
switch (value)
{
case bool v:
valueOffsets.Add(Value.CreateValue(builder, columnIndex, bool_value: v));
break;
case int v:
valueOffsets.Add(Value.CreateValue(builder, columnIndex, int_value: v));
break;
case long v:
valueOffsets.Add(Value.CreateValue(builder, columnIndex, long_value: v));
break;
case double v:
valueOffsets.Add(Value.CreateValue(builder, columnIndex, double_value: v));
break;
case string v:
valueOffsets.Add(Value.CreateValue(builder, columnIndex, string_valueOffset: builder.CreateString(v)));
break;
case null:
break;
default: throw new ApplicationException("Unknown type");
}
}
}
valuesOffset = Feature.CreateValuesVector(builder, valueOffsets.ToArray());
}
Feature.StartFeature(builder);
Feature.AddGeometry(builder, geometryOffset);
Feature.AddLayer(builder, layerIndex);
if (valuesOffset.HasValue)
{
Feature.AddValues(builder, valuesOffset.Value);
}
var offset = Feature.EndFeature(builder);
builder.FinishSizePrefixed(offset.Value);
var bytes = builder.DataBuffer.ToSizedArray();
return(bytes);
}
public static ByteBuffer ToByteBuffer(IFeature feature, ref Header header)
{
var builder = new FlatBufferBuilder(1024);
GeometryType geometryType;
if (header.GeometryType != GeometryType.Unknown)
{
geometryType = header.GeometryType;
}
else
{
geometryType = GeometryConversions.ToGeometryType(feature.Geometry);
}
var go = GeometryConversions.BuildGeometry(builder, feature.Geometry, geometryType, ref header);
var memoryStream = new MemoryStream();
if (feature.Attributes != null && feature.Attributes.Count > 0 && header.ColumnsLength > 0)
{
var writer = new BinaryWriter(memoryStream, Encoding.UTF8);
for (ushort i = 0; i < header.ColumnsLength; i++)
{
var column = header.Columns(i).Value;
var type = column.Type;
var name = column.Name;
if (!feature.Attributes.Exists(name))
{
continue;
}
var value = feature.Attributes[name];
if (value is null)
{
continue;
}
writer.Write(i);
switch (type)
{
case ColumnType.Bool:
writer.Write((bool)value);
break;
case ColumnType.Int:
writer.Write((int)value);
break;
case ColumnType.Long:
writer.Write((long)value);
break;
case ColumnType.Double:
writer.Write((double)value);
break;
case ColumnType.String:
var bytes = Encoding.UTF8.GetBytes((string)value);
writer.Write(bytes.Length);
writer.Write(bytes);
break;
default:
throw new ApplicationException("Unknown type " + value.GetType().FullName);
}
}
}
var propertiesOffset = default(VectorOffset);
if (memoryStream.Position > 0)
{
propertiesOffset = Feature.CreatePropertiesVectorBlock(builder, memoryStream.ToArray());
}
Offset <Geometry> geometryOffset;
if (go.gos != null && go.gos.Length > 0)
{
var partOffsets = new Offset <Geometry> [go.gos.Length];
for (int i = 0; i < go.gos.Length; i++)
{
var goPart = go.gos[i];
var partOffset = Geometry.CreateGeometry(builder, goPart.endsOffset, goPart.xyOffset, goPart.zOffset, goPart.mOffset, default, default, go.Type, default);