001/** 002 * 003 * Copyright (c) 2014, the Railo Company Ltd. All rights reserved. 004 * 005 * This library is free software; you can redistribute it and/or 006 * modify it under the terms of the GNU Lesser General Public 007 * License as published by the Free Software Foundation; either 008 * version 2.1 of the License, or (at your option) any later version. 009 * 010 * This library is distributed in the hope that it will be useful, 011 * but WITHOUT ANY WARRANTY; without even the implied warranty of 012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 013 * Lesser General Public License for more details. 014 * 015 * You should have received a copy of the GNU Lesser General Public 016 * License along with this library. If not, see <http://www.gnu.org/licenses/>. 017 * 018 **/ 019package lucee.runtime.img.interpolation; 020 021public class Lanczos implements Interpolation 022{ 023 public double f(double x) { 024 if (x < -3.0) 025 return 0.0; 026 if (x < 0.0) 027 return sinc(-x) * sinc(-x / 3.0); 028 if (x < 3.0) 029 return sinc(x) * sinc(x / 3.0); 030 return 0.0; 031 } 032 033 public double sinc(double x) { 034 x *= 3.141592653589793; 035 if (x != 0.0) 036 return Math.sin(x) / x; 037 return 1.0; 038 } 039 040 public double getSupport() { 041 return 3.0; 042 } 043}