/src/libreoffice/vcl/inc/ResampleKernel.hxx
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1 | | /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ |
2 | | /* |
3 | | * This file is part of the LibreOffice project. |
4 | | * |
5 | | * This Source Code Form is subject to the terms of the Mozilla Public |
6 | | * License, v. 2.0. If a copy of the MPL was not distributed with this |
7 | | * file, You can obtain one at http://mozilla.org/MPL/2.0/. |
8 | | * |
9 | | * This file incorporates work covered by the following license notice: |
10 | | * |
11 | | * Licensed to the Apache Software Foundation (ASF) under one or more |
12 | | * contributor license agreements. See the NOTICE file distributed |
13 | | * with this work for additional information regarding copyright |
14 | | * ownership. The ASF licenses this file to you under the Apache |
15 | | * License, Version 2.0 (the "License"); you may not use this file |
16 | | * except in compliance with the License. You may obtain a copy of |
17 | | * the License at http://www.apache.org/licenses/LICENSE-2.0 . |
18 | | */ |
19 | | |
20 | | #pragma once |
21 | | |
22 | | #include <boost/math/special_functions/sinc.hpp> |
23 | | |
24 | | namespace vcl { |
25 | | |
26 | | // Resample kernels |
27 | | |
28 | | class Kernel |
29 | | { |
30 | | public: |
31 | 0 | Kernel() {} |
32 | 0 | virtual ~Kernel() {} |
33 | | |
34 | | virtual double GetWidth() const = 0; |
35 | | virtual double Calculate( double x ) const = 0; |
36 | | }; |
37 | | |
38 | | class Lanczos3Kernel final : public Kernel |
39 | | { |
40 | | public: |
41 | 0 | Lanczos3Kernel() : Kernel () {} |
42 | | |
43 | 0 | virtual double GetWidth() const override { return 3.0; } |
44 | | virtual double Calculate (double x) const override |
45 | 0 | { |
46 | 0 | return (-3.0 <= x && x < 3.0) ? SincFilter(x) * SincFilter( x / 3.0 ) : 0.0; |
47 | 0 | } |
48 | | |
49 | | static double SincFilter(double x) |
50 | 0 | { |
51 | 0 | if (x == 0.0) |
52 | 0 | { |
53 | 0 | return 1.0; |
54 | 0 | } |
55 | 0 | x = x * M_PI; |
56 | 0 | return boost::math::sinc_pi(x, SincPolicy()); |
57 | 0 | } |
58 | | |
59 | | private: |
60 | | typedef boost::math::policies::policy< |
61 | | boost::math::policies::promote_double<false> > SincPolicy; |
62 | | }; |
63 | | |
64 | | class BicubicKernel final : public Kernel |
65 | | { |
66 | | public: |
67 | 0 | BicubicKernel() : Kernel () {} |
68 | | |
69 | | private: |
70 | 0 | virtual double GetWidth() const override { return 2.0; } |
71 | | virtual double Calculate (double x) const override |
72 | 0 | { |
73 | 0 | if (x < 0.0) |
74 | 0 | { |
75 | 0 | x = -x; |
76 | 0 | } |
77 | |
|
78 | 0 | if (x <= 1.0) |
79 | 0 | { |
80 | 0 | return (1.5 * x - 2.5) * x * x + 1.0; |
81 | 0 | } |
82 | 0 | else if (x < 2.0) |
83 | 0 | { |
84 | 0 | return ((-0.5 * x + 2.5) * x - 4) * x + 2; |
85 | 0 | } |
86 | 0 | return 0.0; |
87 | 0 | } |
88 | | }; |
89 | | |
90 | | class BilinearKernel final : public Kernel |
91 | | { |
92 | | public: |
93 | 0 | BilinearKernel() : Kernel () {} |
94 | | |
95 | | private: |
96 | 0 | virtual double GetWidth() const override { return 1.0; } |
97 | | virtual double Calculate (double x) const override |
98 | 0 | { |
99 | 0 | if (x < 0.0) |
100 | 0 | { |
101 | 0 | x = -x; |
102 | 0 | } |
103 | 0 | if (x < 1.0) |
104 | 0 | { |
105 | 0 | return 1.0-x; |
106 | 0 | } |
107 | 0 | return 0.0; |
108 | 0 | } |
109 | | }; |
110 | | |
111 | | } // namespace vcl |
112 | | |
113 | | /* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |