xref: /third_party/ffmpeg/libavutil/display.c (revision cabdff1a) 
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 "libm.h"
27#include "mathematics.h"
28
29// fixed point to double
30#define CONV_FP(x) ((double) (x)) / (1 << 16)
31
32// double to fixed point
33#define CONV_DB(x) (int32_t) ((x) * (1 << 16))
34
35double av_display_rotation_get(const int32_t matrix[9])
36{
37    double rotation, scale[2];
38
39    scale[0] = hypot(CONV_FP(matrix[0]), CONV_FP(matrix[3]));
40    scale[1] = hypot(CONV_FP(matrix[1]), CONV_FP(matrix[4]));
41
42    if (scale[0] == 0.0 || scale[1] == 0.0)
43        return NAN;
44
45    rotation = atan2(CONV_FP(matrix[1]) / scale[1],
46                     CONV_FP(matrix[0]) / scale[0]) * 180 / M_PI;
47
48    return -rotation;
49}
50
51void av_display_rotation_set(int32_t matrix[9], double angle)
52{
53    double radians = -angle * M_PI / 180.0f;
54    double c = cos(radians);
55    double s = sin(radians);
56
57    memset(matrix, 0, 9 * sizeof(int32_t));
58
59    matrix[0] = CONV_DB(c);
60    matrix[1] = CONV_DB(-s);
61    matrix[3] = CONV_DB(s);
62    matrix[4] = CONV_DB(c);
63    matrix[8] = 1 << 30;
64}
65
66void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
67{
68    int i;
69    const int flip[] = { 1 - 2 * (!!hflip), 1 - 2 * (!!vflip), 1 };
70
71    if (hflip || vflip)
72        for (i = 0; i < 9; i++)
73            matrix[i] *= flip[i % 3];
74}
75