/// <summary>
/// Reads the entire index file in order to get a breakdown of how shapes are broken up.
/// </summary>
/// <param name="fileName">A string fileName of the .shx file to read.</param>
/// <returns>A List of ShapeHeaders that give offsets and lengths so that reading can be optimized</returns>
protected List <ShapeHeader> ReadIndexFile(string fileName)
{
string shxFilename = fileName;
string ext = Path.GetExtension(fileName);
if (ext != ".shx")
{
shxFilename = Path.ChangeExtension(fileName, ".shx");
}
if (shxFilename == null)
{
throw new NullReferenceException(fileName);
}
if (File.Exists(shxFilename) == false)
{
throw new FileNotFoundException(fileName);
}
// This will store the header elements that we read from the file.
List <ShapeHeader> result = new List <ShapeHeader>();
// Use a the length of the file to dimension the byte array
BufferedBinaryReader bbReader = new BufferedBinaryReader(shxFilename);
if (bbReader.FileLength == 100)
{
// the file is empty, so we are done
bbReader.Close();
return(result);
}
// Skip the header and begin reading from the first record
bbReader.Seek(100, SeekOrigin.Begin);
Header.ShxLength = (int)bbReader.FileLength / 2;
long length = bbReader.FileLength - 100;
long numRecords = length / 8; // Each record consists of 2 Big-endian integers for a total of 8 bytes.
for (long i = 0; i < numRecords; i++)
{
ShapeHeader sh = new ShapeHeader
{
Offset = bbReader.ReadInt32(false),
ContentLength = bbReader.ReadInt32(false)
};
result.Add(sh);
}
bbReader.Close();
return(result);
}
/// <summary>
/// Reads the entire index file in order to get a breakdown of how shapes are broken up.
/// </summary>
/// <param name="fileName">A string fileName of the .shx file to read.</param>
/// <returns>A List of ShapeHeaders that give offsets and lengths so that reading can be optimized</returns>
public List<ShapeHeader> ReadIndexFile(string fileName)
{
string shxFilename = fileName;
string ext = Path.GetExtension(fileName);
if (ext != ".shx")
{
shxFilename = Path.ChangeExtension(fileName, ".shx");
}
if (shxFilename == null)
{
throw new NullReferenceException(DataStrings.ArgumentNull_S.Replace("%S", fileName));
}
if (File.Exists(shxFilename) == false)
{
throw new FileNotFoundException(DataStrings.FileNotFound_S.Replace("%S", fileName));
}
// This will store the header elements that we read from the file.
List<ShapeHeader> result = new List<ShapeHeader>();
// Use a the length of the file to dimension the byte array
BufferedBinaryReader bbReader = new BufferedBinaryReader(shxFilename);
if (bbReader.FileLength == 100)
{
// the file is empty, so we are done
bbReader.Close();
return result;
}
// Skip the header and begin reading from the first record
bbReader.Seek(100, SeekOrigin.Begin);
_header.ShxLength = (int)bbReader.FileLength / 2;
long length = bbReader.FileLength - 100;
long numRecords = length / 8; // Each record consists of 2 Big-endian integers for a total of 8 bytes.
for (long i = 0; i < numRecords; i++)
{
ShapeHeader sh = new ShapeHeader
{
Offset = bbReader.ReadInt32(false),
ContentLength = bbReader.ReadInt32(false)
};
result.Add(sh);
}
bbReader.Close();
return result;
}
