package org.geotools.geopkg.geom;
import java.io.IOException;
import java.io.InputStream;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.io.ByteArrayInStream;
import com.vividsolutions.jts.io.ByteOrderDataInStream;
import com.vividsolutions.jts.io.InStream;
import com.vividsolutions.jts.io.InputStreamInStream;
import com.vividsolutions.jts.io.ParseException;
import com.vividsolutions.jts.io.WKBReader;
public class GeoPkgGeomReader {
public Geometry read(byte[] bytes) throws IOException {
return read(new ByteArrayInStream(bytes));
}
public Geometry read(InputStream in) throws IOException {
return read(new InputStreamInStream(in));
}
Geometry read(InStream input) throws IOException {
// read the header
Header h = readHeader(input);
// read the geometry
try {
Geometry g = new WKBReader().read(input);
g.setSRID(h.srid);
return g;
} catch (ParseException e) {
throw new IOException(e);
}
}
/*
* OptimizedGeoPackageBinary {
* byte[3] magic = 0x47504230; // 'GPB'
* byte flags; // see flags layout below
* unit32 srid;
* double[] envelope; // see flags envelope contents indicator code below
* WKBGeometry geometry; // per OGC 06-103r4 clause 8
*
*
* flags layout:
* bit 7 6 5 4 3 2 1 0
* use V V V V E E E B
* use:
* V: version number (4-bit unsigned integer)
* 0 = version 1
*
* E: envelope contents indicator code (3-bit unsigned integer)
* value | description | envelope length (bytes)
* 0 | no envelope (space saving slower indexing option) | 0
* 1 | envelope is [minx, maxx, miny, maxy] | 32
* 2 | envelope is [minx, maxx, miny, maxy, minz, maxz] | 48
* 3 | envelope is [minx, maxx, miny, maxy, minm, maxm] | 48
* 4 | envelope is [minx, maxx, miny, maxy, minz, maxz, minm, maxm] | 64
* B: byte order for header values (1-bit Boolean)
* 0 = Big Endian (most significant bit first)
* 1 = Little Endian (least significant bit first)
*/
Header readHeader(InStream in) throws IOException {
Header h = new Header();
// read first 4 bytes
// TODO: something with the magic number
byte[] buf = new byte[4];
in.read(buf);
// next byte flags
h.flags = new Flags((byte)buf[3]);
// set endianness
ByteOrderDataInStream din = new ByteOrderDataInStream(in);
din.setOrder(h.flags.getEndianess());
// read the srid
h.srid = din.readInt();
// read the envlope
if (h.flags.getEnvelopeIndicator() != EnvelopeType.NONE) {
double x1 = din.readDouble();
double x2 = din.readDouble();
double y1 = din.readDouble();
double y2 = din.readDouble();
if (h.flags.getEnvelopeIndicator().value > 1) {
// 2 = minz,maxz; 3 = minm,maxm - we ignore these for now
din.readDouble();
din.readDouble();
}
if (h.flags.getEnvelopeIndicator().value > 3) {
// 4 = minz,maxz,minm,maxm - we ignore these for now
din.readDouble();
din.readDouble();
}
h.envelope = new Envelope(x1, x2, y1, y2);
}
return h;
}
}