FilterFunction_startAngle.java

package org.geotools.filter.function;

/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 * 
 *    (C) 2005-2008, Open Source Geospatial Foundation (OSGeo)
 *    
 *    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;
 *    version 2.1 of the License.
 *
 *    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.
 */

//this code is autogenerated - you shouldnt be modifying it!
import org.geotools.filter.FunctionExpressionImpl;

import com.vividsolutions.jts.geom.CoordinateSequence;
import com.vividsolutions.jts.geom.LineString;

public class FilterFunction_startAngle extends FunctionExpressionImpl {

	public FilterFunction_startAngle() {
		super("startAngle");
	}

	public int getArgCount() {
		return 1;
	}

	public Object evaluate(Object feature) {
		LineString ls;

		try { // attempt to get value and perform conversion
			ls = (LineString) getExpression(0).evaluate(feature, LineString.class);
		} catch (Exception e) {
			// probably a type error
			throw new IllegalArgumentException(
					"Filter Function problem for function startAngle argument #0 - expected type Geometry");
		}
		if(ls == null || ls.getNumPoints() == 1) {
			return null;
		}
		
		CoordinateSequence cs = ls.getCoordinateSequence();
		
        double dx = (cs.getX(1) - cs.getX(0));
        double dy = (cs.getY(1) - cs.getY(0));
        return -Math.toDegrees(Math.atan2(dy, dx));
	}
}