| private SwapByteOrder ( int i ) : int | ||
| i | int | Integer to swap |
| return | int | |
public bool MoveNext()
{
if (_shpStream.Position >= _shpHeader.FileLength)
{
_current = new ShapeFileIndexEntry();
return(false);
}
// Get the record offset
var recordOffset = (int)_shpStream.Position;
// Get the oid
var oid = ShapeFile.SwapByteOrder(_shpReader.ReadInt32());
Debug.Assert(oid == _lastOid + 1);
_lastOid = oid;
// Get the record length
var recordLength = 2 * ShapeFile.SwapByteOrder(_shpReader.ReadInt32());
// Set the current ShapeFileIndexEntry
_current = new ShapeFileIndexEntry(recordOffset, recordLength);
// Adjust the streams position
_shpStream.Seek(recordLength, SeekOrigin.Current);
return(true);
}
/// <summary>
/// Creates an instance of this class using the provided <paramref name="headerReader"/>.
/// </summary>
/// <param name="headerReader">The stream holding the header information</param>
public ShapeFileHeader(BinaryReader headerReader)
{
// Check file header
if (headerReader.ReadInt32() != 170328064)
{
//File Code is actually 9994, but in Little Endian Byte Order this is '170328064'
throw (new ApplicationException("Invalid Shapefile (.shp)"));
}
// Get file length
headerReader.BaseStream.Seek(20, SeekOrigin.Current);
FileLength = 2 * ShapeFile.SwapByteOrder(headerReader.ReadInt32());
// Check file Version
if (headerReader.ReadInt32() != ShapeFileVersion)
{
throw (new ApplicationException("Invalid Shapefile version"));
}
// Get the shape type
ShapeType = (ShapeType)headerReader.ReadInt32();
// Get the bounding box
_envelope = new Envelope(new Coordinate(headerReader.ReadDouble(), headerReader.ReadDouble()),
new Coordinate(headerReader.ReadDouble(), headerReader.ReadDouble()));
// Get the Z-range
ZRange = Interval.Create(headerReader.ReadDouble(), headerReader.ReadDouble());
// Get the Z-range
MRange = Interval.Create(ParseNoDataValue(headerReader.ReadDouble()),
ParseNoDataValue(headerReader.ReadDouble()));
}
/// <summary>
/// Method to create a SHX index from a given ShapeFile
/// </summary>
/// <param name="shpPath">The path to the shapefile</param>
public static void Create(string shpPath)
{
if (string.IsNullOrEmpty(shpPath))
{
throw new ArgumentNullException(shpPath);
}
if (!File.Exists(shpPath))
{
throw new FileNotFoundException("The specified path does not lead to a file", shpPath);
}
var shxPath = Path.ChangeExtension(shpPath, ".shx");
if (File.Exists(shxPath))
{
File.Delete(shxPath);
}
using (var it = new ShapeFileEnumerator(shpPath))
{
var fs = new FileStream(shxPath, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.None);
fs.Seek(100, SeekOrigin.Begin);
using (var bw = new BinaryWriter(fs))
{
var count = 0;
while (it.MoveNext())
{
count++;
bw.Write(ShapeFile.SwapByteOrder(it.Current.Offset / 2));
bw.Write(ShapeFile.SwapByteOrder(it.Current.Length / 2));
}
var length = (int)bw.BaseStream.Position;
Debug.Assert(100 + count * 8 == length);
bw.BaseStream.Seek(24, SeekOrigin.Begin);
bw.Write(ShapeFile.SwapByteOrder(length / 2));
bw.BaseStream.Seek(length, SeekOrigin.Begin);
}
}
}
public ShapeFileIndex(Stream stream)
{
stream.Seek(24, SeekOrigin.Begin);
var buf = new byte[4];
stream.Read(buf, 0, 4);
var bufferSize = 2 * ShapeFile.SwapByteOrder(BitConverter.ToInt32(buf, 0)) - 100;
_shxBuffer = new byte[bufferSize];
stream.Seek(100, SeekOrigin.Begin);
stream.Read(_shxBuffer, 0, bufferSize);
for (var i = 0; i < bufferSize; i += 4)
{
var value = 2 * ShapeFile.SwapByteOrder(BitConverter.ToInt32(_shxBuffer, i));
var tmp = BitConverter.GetBytes(value);
Buffer.BlockCopy(tmp, 0, _shxBuffer, i, 4);
}
FeatureCount = (bufferSize) / 8;
}
