/// <summary>
/// Reads the header of a Shapefile
/// </summary>
/// <param name="reader">The Shapefile stream</param>
/// <returns>The shapefile header</returns>
private void ReadFileHeader(BinaryReader reader, out ShapefileShapeType shapeType, out BoundingBox bounds)
{
// Read File Code.
int FileCode = NumberReader.ReadIntBE(reader);
//Verify that the file has the correct file code (9994)
if (FileCode != 9994)
{
throw new FormatException("Invalid FileCode encountered. Expecting a file code of 9994.");
}
//Skip unused section
reader.BaseStream.Seek(20, SeekOrigin.Current);
// Read the File Length.
long fileLength = NumberReader.ReadIntBE(reader);
// Skip the Version number of the shapefile.
reader.BaseStream.Seek(4, SeekOrigin.Current);
// Get the shape type of the shapefile. Note that shapefiles can only contain one type of shape per file
shapeType = (ShapefileShapeType)NumberReader.ReadIntLE(reader);
// Get the bounding box of the Bounding Box.
bounds = ReadBoundingBox(reader);
}
/// <summary>
/// Reads the header of the shapefile
/// </summary>
/// <param name="reader">A Shapefile as a BinaryReader</param>
/// <param name="shapeType">The type of shapes contained in the Shapefile.</param>
/// <param name="bounds">Bounding box of the shapes in the Shapefile.</param>
public void ReadHeader(BinaryReader reader, out ShapefileShapeType shapeType, out BoundingBox bounds)
{
using (reader)
{
// Read the File Header.
ReadFileHeader(reader, out shapeType, out bounds);
}
}
/// <summary>
/// Reads the header of the shapefile
/// </summary>
/// <param name="stream">A Shapefile as a Stream</param>
/// <param name="shapeType">The type of shapes contained in the Shapefile.</param>
/// <param name="bounds">Bounding box of the shapes in the Shapefile.</param>
public void ReadHeader(Stream stream, out ShapefileShapeType shapeType, out BoundingBox bounds)
{
using (BinaryReader reader = new BinaryReader(stream))
{
// Read the File Header.
ReadFileHeader(reader, out shapeType, out bounds);
}
}
/// <summary>
/// Reads all shapes in the Shapefile
/// </summary>
/// <param name="reader">The Shapefile stream</param>
/// <param name="shapeType">The type of shape to read</param>
/// <returns>A list of Geometry objects</returns>
private async Task <List <Geometry> > ReadShapeRecords(BinaryReader reader, ShapefileShapeType shapeType)
{
List <Geometry> items = null;
// Skip the end of the file header.
reader.BaseStream.Seek(100, SeekOrigin.Begin);
// Read the shapes depending on the ShapeType.
switch (shapeType)
{
case ShapefileShapeType.NullShape: // Do nothing.
break;
case ShapefileShapeType.Point:
case ShapefileShapeType.PointZ:
case ShapefileShapeType.PointM:
case ShapefileShapeType.PointZM:
items = ReadPointData(reader);
break;
case ShapefileShapeType.LineString:
case ShapefileShapeType.LineStringZ:
case ShapefileShapeType.LineStringM:
case ShapefileShapeType.LineStringZM:
items = await ReadLineStringData(reader);
break;
case ShapefileShapeType.Polygon:
case ShapefileShapeType.PolygonZ:
case ShapefileShapeType.PolygonM:
case ShapefileShapeType.PolygonZM:
items = ReadPolygonData(reader);
break;
case ShapefileShapeType.MultiPoint:
case ShapefileShapeType.MultiPointZ:
case ShapefileShapeType.MultiPointM:
case ShapefileShapeType.MultiPointZM:
items = ReadMultiPointData(reader);
break;
default: //throw an error indicating that an unsupported shape type is in the file
throw new Exception("ShapeType " + shapeType.ToString() + " is not supported.");
}
return(items);
}
