public static FeatureCollection FromFlatGeobuf(byte[] bytes)
{
var fc = new NetTopologySuite.Features.FeatureCollection();
var bb = new ByteBuffer(bytes);
var headerSize = (ulong)ByteBufferUtil.GetSizePrefix(bb);
bb.Position = FlatBufferConstants.SizePrefixLength;
var header = Header.GetRootAsHeader(bb);
var count = header.FeaturesCount;
var featuresSize = header.FeaturesSize;
var nodeSize = header.IndexNodeSize;
bb.Position += (int)headerSize;
var index = new PackedHilbertRTree(count, nodeSize);
var indexData = bytes.Skip((int)(headerSize + featuresSize)).Take((int)index.Size).ToArray();
index.Load(indexData);
while (count-- > 0)
{
var featureLength = ByteBufferUtil.GetSizePrefix(bb);
bb.Position += FlatBufferConstants.SizePrefixLength;
var feature = FeatureConversions.FromByteBuffer(bb, header);
fc.Add(feature);
bb.Position += featureLength;
}
return(fc);
}
public static FeatureCollection FromFlatGeobuf(byte[] bytes)
{
var fc = new NetTopologySuite.Features.FeatureCollection();
var bb = new ByteBuffer(bytes);
var headerSize = ByteBufferUtil.GetSizePrefix(bb);
bb.Position = FlatBufferConstants.SizePrefixLength;
var header = Header.GetRootAsHeader(bb);
var count = header.FeaturesCount;
var nodeSize = header.IndexNodeSize;
var geometryType = header.GeometryType;
var dimensions = header.Dimensions;
IList <ColumnMeta> columns = null;
if (header.ColumnsLength > 0)
{
columns = new List <ColumnMeta>();
for (int i = 0; i < header.ColumnsLength; i++)
{
var column = header.Columns(i).Value;
columns.Add(new ColumnMeta()
{
Name = column.Name, Type = column.Type
});
}
}
bb.Position += headerSize;
if (nodeSize > 0)
{
var index = new PackedHilbertRTree(count, nodeSize);
var indexData = bytes.Skip(headerSize).Take((int)index.Size).ToArray();
index.Load(indexData);
bb.Position += (int)index.Size + (int)count * 8;
}
while (bb.Position < bb.Length)
{
var featureLength = ByteBufferUtil.GetSizePrefix(bb);
bb.Position += FlatBufferConstants.SizePrefixLength;
var feature = FeatureConversions.FromByteBuffer(bb, geometryType, dimensions, columns);
fc.Add(feature);
bb.Position += featureLength;
}
return(fc);
}
public static IEnumerable <IFeature> Deserialize(Stream stream, Envelope rect = null)
{
var reader = new BinaryReader(stream);
var magicBytes = reader.ReadBytes(8);
if (!magicBytes.SequenceEqual(Constants.MagicBytes))
{
throw new Exception("Not a FlatGeobuf file");
}
var headerSize = reader.ReadInt32();
var header = Header.GetRootAsHeader(new ByteBuffer(reader.ReadBytes(headerSize)));
var count = header.FeaturesCount;
var nodeSize = header.IndexNodeSize;
var geometryType = header.GeometryType;
IList <ColumnMeta> columns = null;
if (header.ColumnsLength > 0)
{
columns = new List <ColumnMeta>();
for (int i = 0; i < header.ColumnsLength; i++)
{
var column = header.Columns(i).Value;
columns.Add(new ColumnMeta()
{
Name = column.Name, Type = column.Type
});
}
}
if (nodeSize > 0)
{
long offset = 8 + 4 + headerSize;
var size = PackedRTree.CalcSize(count, nodeSize);
if (rect != null)
{
var result = PackedRTree.StreamSearch(count, nodeSize, rect, (ulong treeOffset, ulong size) => {
stream.Seek(offset + (long)treeOffset, SeekOrigin.Begin);
return(stream);
}).ToList();
foreach (var item in result)
{
stream.Seek(offset + (long)size + (long)item.Offset, SeekOrigin.Begin);
var featureLength = reader.ReadInt32();
var feature = FeatureConversions.FromByteBuffer(new ByteBuffer(reader.ReadBytes(featureLength)), geometryType, 2, columns);
yield return(feature);
}
yield break;
}
stream.Seek(8 + 4 + headerSize + (long)size, SeekOrigin.Begin);
}
while (stream.Position < stream.Length)
{
var featureLength = reader.ReadInt32();
var feature = FeatureConversions.FromByteBuffer(new ByteBuffer(reader.ReadBytes(featureLength)), geometryType, 2, columns);
yield return(feature);
}
}