/*
  * Copyright (c) 2014 Vittorio Giovara <vittorio.giovara@gmail.com>
  *

  * This file is part of FFmpeg.

  *

  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #ifndef AVUTIL_DISPLAY_H
 #define AVUTIL_DISPLAY_H
 
 #include <stdint.h>
 
 /**
  * The display transformation matrix specifies an affine transformation that
  * should be applied to video frames for correct presentation. It is compatible
  * with the matrices stored in the ISO/IEC 14496-12 container format.
  *
  * The data is a 3x3 matrix represented as a 9-element array:
  *
  *                                  | a b u |
  *   (a, b, u, c, d, v, x, y, w) -> | c d v |
  *                                  | x y w |
  *
  * All numbers are stored in native endianness, as 16.16 fixed-point values,
  * except for u, v and w, which are stored as 2.30 fixed-point values.
  *
  * The transformation maps a point (p, q) in the source (pre-transformation)
  * frame to the point (p', q') in the destination (post-transformation) frame as
  * follows:
  *               | a b u |
  *   (p, q, 1) . | c d v | = z * (p', q', 1)
  *               | x y w |
  *
  * The transformation can also be more explicitly written in components as
  * follows:
  *   p' = (a * p + c * q + x) / z;
  *   q' = (b * p + d * q + y) / z;
  *   z  =  u * p + v * q + w
  */
 
 /**
  * Extract the rotation component of the transformation matrix.
  *
  * @param matrix the transformation matrix
  * @return the angle (in degrees) by which the transformation rotates the frame.
  *         The angle will be in range [-180.0, 180.0], or NaN if the matrix is
  *         singular.
  *
  * @note floating point numbers are inherently inexact, so callers are
  *       recommended to round the return value to nearest integer before use.
  */
 double av_display_rotation_get(const int32_t matrix[9]);
 
 /**
  * Initialize a transformation matrix describing a pure rotation by the
  * specified angle (in degrees).
  *
  * @param matrix an allocated transformation matrix (will be fully overwritten
  *               by this function)
  * @param angle rotation angle in degrees.
  */
 void av_display_rotation_set(int32_t matrix[9], double angle);
 

 /**
  * Flip the input matrix horizontally and/or vertically.
  *
  * @param matrix an allocated transformation matrix
  * @param hflip whether the matrix should be flipped horizontally
  * @param vflip whether the matrix should be flipped vertically
  */
 void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip);
 

 #endif /* AVUTIL_DISPLAY_H */