1 /*
2
3 dsh-interpolate Interpolation and easing functions.
4 Copyright (c) 2009-2013 held jointly by the individual authors.
5
6 This library is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published
8 by the Free Software Foundation; either version 3 of the License, or (at
9 your option) any later version.
10
11 This library is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; with out even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
14 License for more details.
15
16 You should have received a copy of the GNU Lesser General Public License
17 along with this library; if not, write to the Free Software Foundation,
18 Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
19
20 > http://www.fsf.org/licensing/licenses/lgpl.html
21 > http://www.opensource.org/licenses/lgpl-license.php
22
23 */
24 package org.dishevelled.interpolate;
25
26 /**
27 * Ease-in-out elastic interpolation function.
28 * <p><img src="../../../../images/ease-in-out-elastic.png" alt="ease-in-out elastic graph" /></p>
29 *
30 * @author Michael Heuer
31 * @version $Revision$ $Date$
32 */
33 public final class EaseInOutElastic
34 implements EasingFunction
35 {
36 /** <code>Math.PI * 2.0d</code>. */
37 private static final double PI_TIMES_2 = Math.PI * 2.0d;
38
39
40 /** {@inheritDoc} */
41 public String toString()
42 {
43 return "ease-in-out-elastic";
44 }
45
46 /** {@inheritDoc} */
47 public Double evaluate(final Double value)
48 {
49 double p = 0.3 * 1.5d;
50 double s = p / 4.0d;
51 double q = 2.0d * value;
52 if (q < 1.0d)
53 {
54 q -= 1.0d;
55 return -0.5d * (Math.pow(2.0d, 10.0d * q) * Math.sin((q - s) * (PI_TIMES_2) / p));
56 }
57 q -= 1.0d;
58 return 0.5d * Math.pow(2.0, -10.0d * q) * Math.sin((q - s) * (PI_TIMES_2) / p) + 1.0d;
59 }
60 }