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The Apache Commons Codec package contains simple encoder and decoders for various formats such as Base64 and Hexadecimal. In addition to these widely used encoders and decoders, the codec package also maintains a collection of phonetic encoding utilities.

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/*
* Copyright (c) 2005, Graph Builder
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of Graph Builder nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

package com.graphbuilder.curve;

/**
The CatmullRomSpline is equal to the CardinalSpline with the value of alpha fixed at 0.5.
The implementation for the CatmullRomSpline is about 10% faster then the CardinalSpline
implementation.

@see com.graphbuilder.curve.CardinalSpline
*/
public class CatmullRomSpline extends ParametricCurve {

	private static final ThreadLocal SHARED_DATA = new ThreadLocal(){
		protected SharedData initialValue() {
			return new SharedData();
		}
	};
	private final SharedData sharedData = SHARED_DATA.get();

	private static class SharedData {
		private double[][] pt = new double[4][];
	}

	public CatmullRomSpline(ControlPath cp, GroupIterator gi) {
		super(cp, gi);
	}

	protected void eval(double[] p) {
		double t = p[p.length - 1];
		double t2 = t * t;
		double t3 = t2 * t;

		// Note: The 0.5 does NOT represent alpha. It is a result of the simplification.

		for (int i = 0; i < p.length - 1; i++) {
			p[i] = 0.5 * ((sharedData.pt[3][i] - sharedData.pt[0][i] + 3 * (sharedData.pt[1][i] - sharedData.pt[2][i])) * t3
				+ (2 * (sharedData.pt[0][i] + 2*sharedData.pt[2][i]) - 5*sharedData.pt[1][i] - sharedData.pt[3][i]) * t2
				+ (sharedData.pt[2][i] - sharedData.pt[0][i]) * t) + sharedData.pt[1][i];
		}
	}

	/**
	Returns a value of 1.
	*/
	public int getSampleLimit() {
		return 1;
	}

	/**
	The requirements for this curve are the group-iterator must be in-range and have a group size of at least 4.
	If these requirements are not met then this method returns quietly.
	*/
	public void appendTo(MultiPath mp) {
		if (!gi.isInRange(0, cp.numPoints()))
			throw new IllegalArgumentException("Group iterator not in range");;
		if (gi.getGroupSize() < 4)
			throw new IllegalArgumentException("Group iterator size < 4");;

		gi.set(0, 0);

		for (int i = 0; i < 4; i++)
			sharedData.pt[i] = cp.getPoint(gi.next()).getLocation();

		double[] d = new double[mp.getDimension() + 1];
		eval(d);

		if (connect)
			mp.lineTo(d);
		else
			mp.moveTo(d);

		gi.set(0, 0);

		while (true) {
			int index_i = gi.index_i();
			int count_j = gi.count_j();

			for (int i = 0; i < 4; i++) {
				if (!gi.hasNext()) {
					return;
				}
				sharedData.pt[i] = cp.getPoint(gi.next()).getLocation();
			}

			gi.set(index_i, count_j);
			gi.next();

			BinaryCurveApproximationAlgorithm.genPts(this, 0.0, 1.0, mp);
		}
	}
}