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());
}
}
public void SingleItemTest()
{
var tree = new PackedHilbertRTree(1);
tree.Add(0, 0, 1, 1);
tree.Finish();
var list = tree.Search(0, 0, 1, 1);
Assert.AreEqual(1, list.Count);
}
public void TwoItemsTest()
{
var tree = new PackedHilbertRTree(2);
tree.Add(0, 0, 1, 1);
tree.Add(2, 2, 3, 3);
tree.Finish();
var result = tree.Search(1, 1, 2, 2);
Assert.AreEqual(2, result.Count);
}
public static byte[] ToFlatGeobuf(FeatureCollection fc, IList <LayerMeta> layers = null)
{
ulong count = (ulong)fc.Features.LongCount();
if (count == 0)
{
throw new ApplicationException("Empty feature collection is not allowed as input");
}
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();
if (layers == null)
{
layers = IntrospectLayers(fc);
}
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, layers);
featuresStream.Write(buffer, 0, buffer.Length);
offetsWriter.Write(offset);
offset += (ulong)buffer.Length;
}
var header = BuildHeader(count, offset, layers, index);
memoryStream.Write(header, 0, header.Length);
featuresStream.WriteTo(memoryStream);
var indexBytes = index.ToBytes();
memoryStream.Write(indexBytes, 0, indexBytes.Length);
offsetsStream.WriteTo(memoryStream);
}
return(memoryStream.ToArray());
}
}
public void SingleItemRoundtripTest()
{
var tree = new PackedHilbertRTree(1);
tree.Add(0, 0, 1, 1);
tree.Finish();
var data = tree.ToBytes();
Assert.AreEqual(tree.Size, (ulong)data.LongLength);
var tree2 = new PackedHilbertRTree(1, 16);
tree2.Load(data);
var list = tree2.Search(0, 0, 1, 1);
Assert.AreEqual(1, list.Count);
}