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display.c
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1 /*
2  * Copyright (c) 2014 Vittorio Giovara <vittorio.giovara@gmail.com>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include <stdint.h>
22 #include <string.h>
23 #include <math.h>
24 
25 #include "display.h"
26 #include "mathematics.h"
27 
28 // fixed point to double
29 #define CONV_FP(x) ((double) (x)) / (1 << 16)
30 
31 // double to fixed point
32 #define CONV_DB(x) (int32_t) ((x) * (1 << 16))
33 
34 double av_display_rotation_get(const int32_t matrix[9])
35 {
36  double rotation, scale[2];
37 
38  scale[0] = hypot(CONV_FP(matrix[0]), CONV_FP(matrix[3]));
39  scale[1] = hypot(CONV_FP(matrix[1]), CONV_FP(matrix[4]));
40 
41  if (scale[0] == 0.0 || scale[1] == 0.0)
42  return NAN;
43 
44  rotation = atan2(CONV_FP(matrix[1]) / scale[1],
45  CONV_FP(matrix[0]) / scale[0]) * 180 / M_PI;
46 
47  return rotation;
48 }
49 
50 void av_display_rotation_set(int32_t matrix[9], double angle)
51 {
52  double radians = angle * M_PI / 180.0f;
53  double c = cos(radians);
54  double s = sin(radians);
55 
56  memset(matrix, 0, 9 * sizeof(int32_t));
57 
58  matrix[0] = CONV_DB(c);
59  matrix[1] = CONV_DB(-s);
60  matrix[3] = CONV_DB(s);
61  matrix[4] = CONV_DB(c);
62  matrix[8] = 1 << 30;
63 }
64 
65 void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
66 {
67  int i;
68  const int flip[] = { 1 - 2 * (!!hflip), 1 - 2 * (!!vflip), 1 };
69 
70  if (hflip || vflip)
71  for (i = 0; i < 9; i++)
72  matrix[i] *= flip[i % 3];
73 }