public FileHeader ReadHeader()
{
using (var stream = MMFCache.GetFileReadItems(_FilePath)
.MMF.CreateViewStream(0, 100))
{
using (var brShapeIndex = new BinaryReader(stream))
{
brShapeIndex.BaseStream.Seek(0, 0);
//Check file header
if (brShapeIndex.ReadInt32() != 170328064) //File Code is actually 9994, but in Little Endian Byte Order this is '170328064'
{
throw (new ApplicationException("Invalid Shapefile Index (.shx)"));
}
brShapeIndex.BaseStream.Seek(24, 0); //seek to File Length
int IndexFileSize = Util.SwapByteOrder(brShapeIndex.ReadInt32()); //Read filelength as big-endian. The length is based on 16bit words
//int IndexFileSize = brShapeIndex.ReadInt32(); //Read filelength as big-endian. The length is based on 16bit words
//_RecordCount = (2 * IndexFileSize - 100) / 8; //Calculate FeatureCount. Each feature takes up 8 bytes. The header is 100 bytes
var version = brShapeIndex.ReadInt32();
// brShapeIndex.BaseStream.Seek(32, 0); //seek to ShapeType
var shapeType = brShapeIndex.ReadInt32();
//Read the spatial bounding box of the contents
brShapeIndex.BaseStream.Seek(36, 0); //seek to box
double x1, x2, y1, y2;
x1 = brShapeIndex.ReadDouble();
y1 = brShapeIndex.ReadDouble();
x2 = brShapeIndex.ReadDouble();
y2 = brShapeIndex.ReadDouble();
var mBR = new Envelope(x1, x2, y1, y2);
var fileHeader = new FileHeader(IndexFileSize, version, shapeType, mBR);
return(fileHeader);
}
}
}
public ShxRecord[] ReadRecordes(int startRecIndex, int count)
{
using (var stream = MMFCache.GetFileReadItems(_FilePath)
.MMF.CreateViewStream(100 + startRecIndex * 8, count * 8))
{
using (var brShapeIndex = new BinaryReader(stream))
{
var records = new ShxRecord[count];
for (int i = 0; i < count; i++)
{
int offset = 2 * Util.SwapByteOrder(brShapeIndex.ReadInt32()); // word to byte
int cLength = 2 * Util.SwapByteOrder(brShapeIndex.ReadInt32());
records[i] = new ShxRecord(offset, cLength);
}
return(records);
}
}
}
public FeatureLite ReaderShape(int recHeaderPos, int recCLength)
{
using (var stream = MMFCache.GetFileReadItems(_FilePath)
.MMF.CreateViewStream(recHeaderPos, recCLength + HEADER_LENGTH))
{
using (var brReader = new BinaryReader(stream))
{
FeatureLite fl;
int fID = Util.SwapByteOrder(brReader.ReadInt32());
int clength = Util.SwapByteOrder(brReader.ReadInt32());
ShapeType shapeType = (ShapeType)brReader.ReadInt32(); // 4
if (shapeType == ShapeType.Point)
{
fl = new FeatureLite(fID, shapeType
, brReader.ReadDouble(), brReader.ReadDouble());
}
else
{
double xMin = brReader.ReadDouble();
double yMin = brReader.ReadDouble();
double xMax = brReader.ReadDouble();
double yMax = brReader.ReadDouble();// 8*4=32
Envelope mbr = new Envelope(xMin, xMax, yMin, yMax);
var shapeBytes = new byte[clength - 36]; // 4+32=36
brReader.BaseStream.Seek(36, 0);
brReader.Read(shapeBytes, 0, clength - 36);
fl = new FeatureLite(fID, shapeType, mbr, shapeBytes);
}
return(fl);
}
}
}
