WKBReader.java

/*
 * Copyright 2013 Hannes Janetzek
 *
 * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
 *
 * This program 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 3 of the License, or (at your option) any later version.
 *
 * This program 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 program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.oscim.utils.wkb;

import org.oscim.core.GeometryBuffer;
import org.oscim.core.Tile;

public class WKBReader {
	public interface Callback {
		public void process(GeometryBuffer geom);
	}

	private final GeometryBuffer mGeom;
	private final boolean mFlipY;

	private WKBReader.Callback mCallback;

	public WKBReader(GeometryBuffer geom, boolean flipY) {
		mGeom = geom;
		mFlipY = flipY;
	}

	public void setCallback(WKBReader.Callback cb) {
		mCallback = cb;
	}

	/**
	 * Parse a binary encoded geometry.
	 */
	public void parse(byte[] value) {
		parseGeometry(valueGetterForEndian(value), 0);
	}

	/**
	 * Parse a hex encoded geometry.
	 */
	public void parse(String value) {
		byte[] b = hexStringToByteArray(value);
		if (b == null)
			return;

		parse(b);
	}

	private void parseGeometry(ValueGetter data, int count) {
		byte endian = data.getByte(); // skip and test endian flag
		if (endian != data.endian) {
			throw new IllegalArgumentException("Endian inconsistency!");
		}
		int typeword = data.getInt();

		int realtype = typeword & 0x1FFFFFFF; // cut off high flag bits

		boolean haveZ = (typeword & 0x80000000) != 0;
		boolean haveM = (typeword & 0x40000000) != 0;
		boolean haveS = (typeword & 0x20000000) != 0;

		// int srid = Geometry.UNKNOWN_SRID;
		if (haveS) {
			// srid = Geometry.parseSRID(data.getInt());
			data.getInt();
		}
		switch (realtype) {
			case Geometry.POINT:
				mGeom.startPoints();
				parsePoint(data, haveZ, haveM);
				break;
			case Geometry.LINESTRING:
				mGeom.startLine();
				parseLineString(data, haveZ, haveM);
				break;
			case Geometry.POLYGON:
				mGeom.startPolygon();
				parsePolygon(data, haveZ, haveM);
				break;
			case Geometry.MULTIPOINT:
				mGeom.startPoints();
				parseMultiPoint(data);
				break;
			case Geometry.MULTILINESTRING:
				mGeom.startLine();
				parseMultiLineString(data);
				break;
			case Geometry.MULTIPOLYGON:
				mGeom.startPolygon();
				parseMultiPolygon(data);
				break;
			case Geometry.GEOMETRYCOLLECTION:
				parseCollection(data);
				break;
			default:
				throw new IllegalArgumentException("Unknown Geometry Type: " + realtype);
		}

		if (count == 0) {
			mCallback.process(mGeom);

			mGeom.clear();
		}
		// if (srid != Geometry.UNKNOWN_SRID) {
		// result.setSrid(srid);
		// }
	}

	private void parsePoint(ValueGetter data, boolean haveZ, boolean haveM) {

		float x = (float) data.getDouble();
		float y = (float) data.getDouble();
		if (mFlipY)
			y = Tile.SIZE - y;

		mGeom.addPoint(x, y);

		if (haveZ)
			data.getDouble();

		if (haveM)
			data.getDouble();
	}

	/**
	 * Parse an Array of "full" Geometries
	 * 
	 * @param data
	 *            ...
	 * @param count
	 *            ...
	 */
	private void parseGeometryArray(ValueGetter data, int count, int type) {
		mGeom.clear();

		for (int i = 0; i < count; i++) {
			if (i > 0) {
				if (type == Geometry.LINESTRING)
					mGeom.startLine();
				else if (type == Geometry.POLYGON)
					mGeom.startPolygon();
				else {
					mCallback.process(mGeom);
					mGeom.clear();
				}
			}
			parseGeometry(data, count);
			// mGeom.index[++mGeom.indexPos] = -1;
		}

		mCallback.process(mGeom);
		mGeom.clear();
	}

	private void parseMultiPoint(ValueGetter data) {
		parseGeometryArray(data, data.getInt(), Geometry.POINT);
	}

	private void parseLineString(ValueGetter data, boolean haveZ, boolean haveM) {

		int count = data.getInt();

		for (int i = 0; i < count; i++) {
			float x = (float) data.getDouble();
			float y = (float) data.getDouble();

			if (mFlipY)
				y = Tile.SIZE - y;

			mGeom.addPoint(x, y);

			// ignore
			if (haveZ)
				data.getDouble();
			if (haveM)
				data.getDouble();
		}
	}

	private void parsePolygon(ValueGetter data, boolean haveZ, boolean haveM) {
		int count = data.getInt();

		for (int i = 0; i < count; i++) {

			if (i > 0)
				mGeom.startHole();

			int points = data.getInt();

			for (int j = 0; j < points; j++) {
				float x = (float) data.getDouble();
				float y = (float) data.getDouble();

				if (mFlipY)
					y = Tile.SIZE - y;

				// drop redundant closing point
				if (j < points - 1)
					mGeom.addPoint(x, y);

				// ignore
				if (haveZ)
					data.getDouble();
				if (haveM)
					data.getDouble();
			}
		}
	}

	private void parseMultiLineString(ValueGetter data) {

		int count = data.getInt();
		if (count <= 0)
			return;

		parseGeometryArray(data, count, Geometry.LINESTRING);
	}

	private void parseMultiPolygon(ValueGetter data) {
		int count = data.getInt();
		if (count <= 0)
			return;

		parseGeometryArray(data, count, Geometry.POLYGON);
	}

	private void parseCollection(ValueGetter data) {
		int count = data.getInt();

		parseGeometryArray(data, count, Geometry.GEOMETRYCOLLECTION);

		mCallback.process(mGeom);
		mGeom.clear();
	}

	private static ValueGetter valueGetterForEndian(byte[] bytes) {
		if (bytes[0] == ValueGetter.XDR.NUMBER) { // XDR
			return new ValueGetter.XDR(bytes);
		} else if (bytes[0] == ValueGetter.NDR.NUMBER) {
			return new ValueGetter.NDR(bytes);
		} else {
			throw new IllegalArgumentException("Unknown Endian type:" + bytes[0]);
		}
	}

	/**
	 * Converting a string of hex character to bytes
	 * 
	 * from http://stackoverflow.com/questions/140131/convert-a-string-
	 * representation-of-a-hex-dump-to-a-byte-array-using-java
	 */
	public static byte[] hexStringToByteArray(String s) {

		int len = s.length();
		if (len < 2)
			return null;

		byte[] data = new byte[len / 2];
		for (int i = 0; i < len; i += 2) {
			data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
			        + Character.digit(s.charAt(i + 1), 16));
		}
		return data;
	}

}