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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. }
  74.