com.vividsolutions.jts.io.WKBWriter Maven / Gradle / Ivy
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/*
* The JTS Topology Suite is a collection of Java classes that
* implement the fundamental operations required to validate a given
* geo-spatial data set to a known topological specification.
*
* Copyright (C) 2001 Vivid Solutions
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* For more information, contact:
*
* Vivid Solutions
* Suite #1A
* 2328 Government Street
* Victoria BC V8T 5G5
* Canada
*
* (250)385-6040
* www.vividsolutions.com
*/
package com.vividsolutions.jts.io;
import java.io.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.util.Assert;
/**
* Writes a {@link Geometry} into Well-Known Binary format.
* Supports use of an {@link OutStream}, which allows easy use
* with arbitary byte stream sinks.
*
* The WKB format is specified in the
* OGC Simple Features for SQL
* specification.
* This implementation also supports the Extended WKB
* standard. Extended WKB allows writing 3-dimensional coordinates
* and including the geometry SRID value.
* The presence of 3D coordinates is signified
* by setting the high bit of the wkbType word.
* The presence of an SRID is signified
* by setting the third bit of the wkbType word.
* EWKB format is upward compatible with the original SFS WKB format.
*
* Empty Points cannot be represented in WKB; an
* {@link IllegalArgumentException} will be thrown if one is
* written.
*
* The WKB specification does not support representing {@link LinearRing}s;
* they will be written as {@link LineString}s.
*
* This class is designed to support reuse of a single instance to read multiple
* geometries. This class is not thread-safe; each thread should create its own
* instance.
*
*
Syntax
* The following syntax specification describes the version of Well-Known Binary
* supported by JTS.
*
* The specification uses a syntax language similar to that used in
* the C language. Bitfields are specified from hi-order to lo-order bits.
*
*
*
* byte = 1 byte
* uint32 = 32 bit unsigned integer (4 bytes)
* double = double precision number (8 bytes)
*
* abstract Point { }
*
* Point2D extends Point {
* double x;
* double y;
* }
*
* Point3D extends Point {
* double x;
* double y;
* double z;
* }
*
* LinearRing {
* uint32 numPoints;
* Point points[numPoints];
* }
*
* enum wkbGeometryType {
* wkbPoint = 1,
* wkbLineString = 2,
* wkbPolygon = 3,
* wkbMultiPoint = 4,
* wkbMultiLineString = 5,
* wkbMultiPolygon = 6,
* wkbGeometryCollection = 7
* }
*
* enum byteOrder {
* wkbXDR = 0, // Big Endian
* wkbNDR = 1 // Little Endian
* }
*
* WKBType {
* uint32 wkbGeometryType : 8; // values from enum wkbGeometryType
* }
*
* EWKBType {
* uint32 is3D : 1; // 0 = 2D, 1 = 3D
* uint32 noData1 : 1;
* uint32 hasSRID : 1; // 0, no, 1 = yes
* uint32 noData2 : 21;
* uint32 wkbGeometryType : 8; // values from enum wkbGeometryType
* }
*
* abstract WKBGeometry {
* byte byteOrder; // values from enum byteOrder
* EWKBType wkbType
* [ uint32 srid; ] // only if hasSRID = yes
* }
*
* WKBPoint extends WKBGeometry {
* Point point;
* }
*
* WKBLineString extends WKBGeometry {
* uint32 numCoords;
* Point points[numCoords];
* }
*
* WKBPolygon extends WKBGeometry {
* uint32 numRings;
* LinearRing rings[numRings];
* }
*
* WKBMultiPoint extends WKBGeometry {
* uint32 numElems;
* WKBPoint elems[numElems];
* }
*
* WKBMultiLineString extends WKBGeometry {
* uint32 numElems;
* WKBLineString elems[numElems];
* }
*
* wkbMultiPolygon extends WKBGeometry {
* uint32 numElems;
* WKBPolygon elems[numElems];
* }
*
* WKBGeometryCollection extends WKBGeometry {
* uint32 numElems;
* WKBGeometry elems[numElems];
* }
*
*
* @see WKBReader
*/
public class WKBWriter
{
/**
* Converts a byte array to a hexadecimal string.
*
* @param bytes
* @return a string of hexadecimal digits
*
* @deprecated
*/
public static String bytesToHex(byte[] bytes)
{
return toHex(bytes);
}
/**
* Converts a byte array to a hexadecimal string.
*
* @param bytes a byte array
* @return a string of hexadecimal digits
*/
public static String toHex(byte[] bytes)
{
StringBuffer buf = new StringBuffer();
for (int i = 0; i < bytes.length; i++) {
byte b = bytes[i];
buf.append(toHexDigit((b >> 4) & 0x0F));
buf.append(toHexDigit(b & 0x0F));
}
return buf.toString();
}
private static char toHexDigit(int n)
{
if (n < 0 || n > 15)
throw new IllegalArgumentException("Nibble value out of range: " + n);
if (n <= 9)
return (char) ('0' + n);
return (char) ('A' + (n - 10));
}
private int outputDimension = 2;
private int byteOrder;
private boolean includeSRID = false;
private ByteArrayOutputStream byteArrayOS = new ByteArrayOutputStream();
private OutStream byteArrayOutStream = new OutputStreamOutStream(byteArrayOS);
// holds output data values
private byte[] buf = new byte[8];
/**
* Creates a writer that writes {@link Geometry}s with
* output dimension = 2 and BIG_ENDIAN byte order
*/
public WKBWriter() {
this(2, ByteOrderValues.BIG_ENDIAN);
}
/**
* Creates a writer that writes {@link Geometry}s with
* the given dimension (2 or 3) for output coordinates
* and {@link ByteOrderValues#BIG_ENDIAN} byte order.
* If the input geometry has a small coordinate dimension,
* coordinates will be padded with {@link Coordinate#NULL_ORDINATE}.
*
* @param outputDimension the coordinate dimension to output (2 or 3)
*/
public WKBWriter(int outputDimension) {
this(outputDimension, ByteOrderValues.BIG_ENDIAN);
}
/**
* Creates a writer that writes {@link Geometry}s with
* the given dimension (2 or 3) for output coordinates
* and {@link ByteOrderValues#BIG_ENDIAN} byte order. This constructor also
* takes a flag to control whether srid information will be
* written.
* If the input geometry has a smaller coordinate dimension,
* coordinates will be padded with {@link Coordinate#NULL_ORDINATE}.
*
* @param outputDimension the coordinate dimension to output (2 or 3)
* @param includeSRID indicates whether SRID should be written
*/
public WKBWriter(int outputDimension, boolean includeSRID) {
this(outputDimension, ByteOrderValues.BIG_ENDIAN, includeSRID);
}
/**
* Creates a writer that writes {@link Geometry}s with
* the given dimension (2 or 3) for output coordinates
* and byte order
* If the input geometry has a small coordinate dimension,
* coordinates will be padded with {@link Coordinate#NULL_ORDINATE}.
*
* @param outputDimension the coordinate dimension to output (2 or 3)
* @param byteOrder the byte ordering to use
*/
public WKBWriter(int outputDimension, int byteOrder) {
this(outputDimension, byteOrder, false);
}
/**
* Creates a writer that writes {@link Geometry}s with
* the given dimension (2 or 3) for output coordinates
* and byte order. This constructor also takes a flag to
* control whether srid information will be written.
* If the input geometry has a small coordinate dimension,
* coordinates will be padded with {@link Coordinate#NULL_ORDINATE}.
*
* @param outputDimension the coordinate dimension to output (2 or 3)
* @param byteOrder the byte ordering to use
* @param includeSRID indicates whether SRID should be written
*/
public WKBWriter(int outputDimension, int byteOrder, boolean includeSRID) {
this.outputDimension = outputDimension;
this.byteOrder = byteOrder;
this.includeSRID = includeSRID;
if (outputDimension < 2 || outputDimension > 3)
throw new IllegalArgumentException("Output dimension must be 2 or 3");
}
/**
* Writes a {@link Geometry} into a byte array.
*
* @param geom the geometry to write
* @return the byte array containing the WKB
*/
public byte[] write(Geometry geom)
{
try {
byteArrayOS.reset();
write(geom, byteArrayOutStream);
}
catch (IOException ex) {
throw new RuntimeException("Unexpected IO exception: " + ex.getMessage());
}
return byteArrayOS.toByteArray();
}
/**
* Writes a {@link Geometry} to an {@link OutStream}.
*
* @param geom the geometry to write
* @param os the out stream to write to
* @throws IOException if an I/O error occurs
*/
public void write(Geometry geom, OutStream os) throws IOException
{
if (geom instanceof Point)
writePoint((Point) geom, os);
// LinearRings will be written as LineStrings
else if (geom instanceof LineString)
writeLineString((LineString) geom, os);
else if (geom instanceof Polygon)
writePolygon((Polygon) geom, os);
else if (geom instanceof MultiPoint)
writeGeometryCollection(WKBConstants.wkbMultiPoint,
(MultiPoint) geom, os);
else if (geom instanceof MultiLineString)
writeGeometryCollection(WKBConstants.wkbMultiLineString,
(MultiLineString) geom, os);
else if (geom instanceof MultiPolygon)
writeGeometryCollection(WKBConstants.wkbMultiPolygon,
(MultiPolygon) geom, os);
else if (geom instanceof GeometryCollection)
writeGeometryCollection(WKBConstants.wkbGeometryCollection,
(GeometryCollection) geom, os);
else {
Assert.shouldNeverReachHere("Unknown Geometry type");
}
}
private void writePoint(Point pt, OutStream os) throws IOException
{
if (pt.getCoordinateSequence().size() == 0)
throw new IllegalArgumentException("Empty Points cannot be represented in WKB");
writeByteOrder(os);
writeGeometryType(WKBConstants.wkbPoint, pt, os);
writeCoordinateSequence(pt.getCoordinateSequence(), false, os);
}
private void writeLineString(LineString line, OutStream os)
throws IOException
{
writeByteOrder(os);
writeGeometryType(WKBConstants.wkbLineString, line, os);
writeCoordinateSequence(line.getCoordinateSequence(), true, os);
}
private void writePolygon(Polygon poly, OutStream os) throws IOException
{
writeByteOrder(os);
writeGeometryType(WKBConstants.wkbPolygon, poly, os);
writeInt(poly.getNumInteriorRing() + 1, os);
writeCoordinateSequence(poly.getExteriorRing().getCoordinateSequence(), true, os);
for (int i = 0; i < poly.getNumInteriorRing(); i++) {
writeCoordinateSequence(poly.getInteriorRingN(i).getCoordinateSequence(), true,
os);
}
}
private void writeGeometryCollection(int geometryType, GeometryCollection gc,
OutStream os) throws IOException
{
writeByteOrder(os);
writeGeometryType(geometryType, gc, os);
writeInt(gc.getNumGeometries(), os);
for (int i = 0; i < gc.getNumGeometries(); i++) {
write(gc.getGeometryN(i), os);
}
}
private void writeByteOrder(OutStream os) throws IOException
{
if (byteOrder == ByteOrderValues.LITTLE_ENDIAN)
buf[0] = WKBConstants.wkbNDR;
else
buf[0] = WKBConstants.wkbXDR;
os.write(buf, 1);
}
private void writeGeometryType(int geometryType, Geometry g, OutStream os)
throws IOException
{
int flag3D = (outputDimension == 3) ? 0x80000000 : 0;
int typeInt = geometryType | flag3D;
typeInt |= includeSRID ? 0x20000000 : 0;
writeInt(typeInt, os);
if (includeSRID) {
writeInt(g.getSRID(), os);
}
}
private void writeInt(int intValue, OutStream os) throws IOException
{
ByteOrderValues.putInt(intValue, buf, byteOrder);
os.write(buf, 4);
}
private void writeCoordinateSequence(CoordinateSequence seq, boolean writeSize, OutStream os)
throws IOException
{
if (writeSize)
writeInt(seq.size(), os);
for (int i = 0; i < seq.size(); i++) {
writeCoordinate(seq, i, os);
}
}
private void writeCoordinate(CoordinateSequence seq, int index, OutStream os)
throws IOException
{
ByteOrderValues.putDouble(seq.getX(index), buf, byteOrder);
os.write(buf, 8);
ByteOrderValues.putDouble(seq.getY(index), buf, byteOrder);
os.write(buf, 8);
// only write 3rd dim if caller has requested it for this writer
if (outputDimension >= 3) {
// if 3rd dim is requested, only write it if the CoordinateSequence provides it
double ordVal = Coordinate.NULL_ORDINATE;
if (seq.getDimension() >= 3)
ordVal = seq.getOrdinate(index, 2);
ByteOrderValues.putDouble(ordVal, buf, byteOrder);
os.write(buf, 8);
}
}
}