1// basisu_resampler.h
2// Copyright (C) 2019 Binomial LLC. All Rights Reserved.
3//
4// Licensed under the Apache License, Version 2.0 (the "License");
5// you may not use this file except in compliance with the License.
6// You may obtain a copy of the License at
7//
8// http://www.apache.org/licenses/LICENSE-2.0
9//
10// Unless required by applicable law or agreed to in writing, software
11// distributed under the License is distributed on an "AS IS" BASIS,
12// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13// See the License for the specific language governing permissions and
14// limitations under the License.
15#pragma once
16#include "../transcoder/basisu.h"
17
18#define BASISU_RESAMPLER_DEBUG_OPS (0)
19#define BASISU_RESAMPLER_DEFAULT_FILTER "lanczos4"
20#define BASISU_RESAMPLER_MAX_DIMENSION (16384)
21
22namespace basisu
23{
24 // float or double
25 typedef float Resample_Real;
26
27 class Resampler
28 {
29 public:
30 typedef Resample_Real Sample;
31
32 struct Contrib
33 {
34 Resample_Real weight;
35 uint16_t pixel;
36 };
37
38 struct Contrib_List
39 {
40 uint16_t n;
41 Contrib *p;
42 };
43
44 enum Boundary_Op
45 {
46 BOUNDARY_WRAP = 0,
47 BOUNDARY_REFLECT = 1,
48 BOUNDARY_CLAMP = 2
49 };
50
51 enum Status
52 {
53 STATUS_OKAY = 0,
54 STATUS_OUT_OF_MEMORY = 1,
55 STATUS_BAD_FILTER_NAME = 2,
56 STATUS_SCAN_BUFFER_FULL = 3
57 };
58
59 // src_x/src_y - Input dimensions
60 // dst_x/dst_y - Output dimensions
61 // boundary_op - How to sample pixels near the image boundaries
62 // sample_low/sample_high - Clamp output samples to specified range, or disable clamping if sample_low >= sample_high
63 // Pclist_x/Pclist_y - Optional pointers to contributor lists from another instance of a Resampler
64 // src_x_ofs/src_y_ofs - Offset input image by specified amount (fractional values okay)
65 Resampler(
66 int src_x, int src_y,
67 int dst_x, int dst_y,
68 Boundary_Op boundary_op = BOUNDARY_CLAMP,
69 Resample_Real sample_low = 0.0f, Resample_Real sample_high = 0.0f,
70 const char *Pfilter_name = BASISU_RESAMPLER_DEFAULT_FILTER,
71 Contrib_List *Pclist_x = NULL,
72 Contrib_List *Pclist_y = NULL,
73 Resample_Real filter_x_scale = 1.0f,
74 Resample_Real filter_y_scale = 1.0f,
75 Resample_Real src_x_ofs = 0.0f,
76 Resample_Real src_y_ofs = 0.0f);
77
78 ~Resampler();
79
80 // Reinits resampler so it can handle another frame.
81 void restart();
82
83 // false on out of memory.
84 bool put_line(const Sample *Psrc);
85
86 // NULL if no scanlines are currently available (give the resampler more scanlines!)
87 const Sample *get_line();
88
89 Status status() const
90 {
91 return m_status;
92 }
93
94 // Returned contributor lists can be shared with another Resampler.
95 void get_clists(Contrib_List **ptr_clist_x, Contrib_List **ptr_clist_y);
96 Contrib_List *get_clist_x() const
97 {
98 return m_Pclist_x;
99 }
100 Contrib_List *get_clist_y() const
101 {
102 return m_Pclist_y;
103 }
104
105 // Filter accessors.
106 static int get_filter_num();
107 static const char *get_filter_name(int filter_num);
108
109 static Contrib_List *make_clist(
110 int src_x, int dst_x, Boundary_Op boundary_op,
111 Resample_Real(*Pfilter)(Resample_Real),
112 Resample_Real filter_support,
113 Resample_Real filter_scale,
114 Resample_Real src_ofs);
115
116 private:
117 Resampler();
118 Resampler(const Resampler &o);
119 Resampler &operator=(const Resampler &o);
120
121#ifdef BASISU_RESAMPLER_DEBUG_OPS
122 int total_ops;
123#endif
124
125 int m_intermediate_x;
126
127 int m_resample_src_x;
128 int m_resample_src_y;
129 int m_resample_dst_x;
130 int m_resample_dst_y;
131
132 Boundary_Op m_boundary_op;
133
134 Sample *m_Pdst_buf;
135 Sample *m_Ptmp_buf;
136
137 Contrib_List *m_Pclist_x;
138 Contrib_List *m_Pclist_y;
139
140 bool m_clist_x_forced;
141 bool m_clist_y_forced;
142
143 bool m_delay_x_resample;
144
145 int *m_Psrc_y_count;
146 uint8_t *m_Psrc_y_flag;
147
148 // The maximum number of scanlines that can be buffered at one time.
149 enum
150 {
151 MAX_SCAN_BUF_SIZE = BASISU_RESAMPLER_MAX_DIMENSION
152 };
153
154 struct Scan_Buf
155 {
156 int scan_buf_y[MAX_SCAN_BUF_SIZE];
157 Sample *scan_buf_l[MAX_SCAN_BUF_SIZE];
158 };
159
160 Scan_Buf *m_Pscan_buf;
161
162 int m_cur_src_y;
163 int m_cur_dst_y;
164
165 Status m_status;
166
167 void resample_x(Sample *Pdst, const Sample *Psrc);
168 void scale_y_mov(Sample *Ptmp, const Sample *Psrc, Resample_Real weight, int dst_x);
169 void scale_y_add(Sample *Ptmp, const Sample *Psrc, Resample_Real weight, int dst_x);
170 void clamp(Sample *Pdst, int n);
171 void resample_y(Sample *Pdst);
172
173 static int reflect(const int j, const int src_x, const Boundary_Op boundary_op);
174
175 inline int count_ops(Contrib_List *Pclist, int k)
176 {
177 int i, t = 0;
178 for (i = 0; i < k; i++)
179 t += Pclist[i].n;
180 return (t);
181 }
182
183 Resample_Real m_lo;
184 Resample_Real m_hi;
185
186 inline Resample_Real clamp_sample(Resample_Real f) const
187 {
188 if (f < m_lo)
189 f = m_lo;
190 else if (f > m_hi)
191 f = m_hi;
192 return f;
193 }
194 };
195
196} // namespace basisu
197