/// <summary>
/// Create a new Shapefile object and open a Shapefile. Note that streams of three files are required -
/// the main file (.shp), the index file (.shx) and the dBASE table (.dbf). The three files
/// must all have the same filename (i.e. shapes.shp, shapes.shx and shapes.dbf).
/// </summary>
/// <param name="mainStream">Stream of .shp for this Shapefile</param>
/// <param name="indexStream">Stream of .shx for this Shapefile</param>
/// <param name="dbfStream">relative path of .dbf for this Shapefile</param>
/// <exception cref="ObjectDisposedException">Thrown if the Shapefile has been disposed</exception>
/// <exception cref="ArgumentNullException">Thrown if the path parameter is null</exception>
/// <exception cref="ArgumentException">Thrown if the path parameter is empty</exception>
/// <exception cref="InvalidOperationException">Thrown if an error occurs parsing file headers</exception>
public void Open(Stream mainStream, Stream indexStream, Stream dbfStream)
{
if (_disposed)
{
throw new ObjectDisposedException("Shapefile");
}
if (mainStream.Length < Header.HeaderLength)
{
throw new InvalidOperationException("Shapefile main file does not contain a valid header");
}
if (indexStream.Length < Header.HeaderLength)
{
throw new InvalidOperationException("Shapefile index file does not contain a valid header");
}
// read in and parse the headers
byte[] headerBytes = new byte[Header.HeaderLength];
_mainStream = mainStream;
_indexStream = indexStream;
_mainStream.Read(headerBytes, 0, Header.HeaderLength);
_mainHeader = new Header(headerBytes);
_indexStream.Read(headerBytes, 0, Header.HeaderLength);
_indexHeader = new Header(headerBytes);
// set properties from the main header
_type = _mainHeader.ShapeType;
_boundingBox = new RectangleD(_mainHeader.XMin, _mainHeader.YMin, _mainHeader.XMax, _mainHeader.YMax);
// index header length is in 16-bit words, including the header - number of
// shapes is the number of records (each 4 workds long) after subtracting the header bytes
_count = (_indexHeader.FileLength - (Header.HeaderLength / 2)) / 4;
dbfReader = new DBFReader(dbfStream, Encoding.ASCII);
dbfReader.ResetReaderToEndOfHeader();
// open the metadata database
//OpenDb(dbfDirectory);
_opened = true;
}