text: /*
   *    rotate.h
   *
   *    Include file for handling image rotation.
   *
   *    Copyright 2004-2005, Per Jonsson (per@pjd.nu)
   *
   *    This software is distributed under the GNU Public license
   *    Version 2.  See also the file 'COPYING'.
   */
  #ifndef _INCLUDE_ROTATE_H
  #define _INCLUDE_ROTATE_H
  
  #include "motion.h" /* for struct context */
  
  /**
   * rotate_init
   * 
   *  Sets up rotation data by allocating a temporary buffer for 90/270 degrees 
   *  rotation, and by determining the right rotate-180-degrees function.
   *
   * Parameters:
   *
   *  cnt - current thread's context structure
   *
   * Returns: nothing
   */
  void rotate_init(struct context *cnt);
  
  /**
   * rotate_deinit
   *
   *  Frees memory allocated by rotate_init. 
   *
   * Parameters:
   *
   *   cnt - current thread's context structure
   */
  void rotate_deinit(struct context *cnt);
  
  /**
   * rotate_map
   * 
   *  Rotates the image stored in map according to the rotation data
   *  available in cnt. Rotation is performed clockwise. Supports 90,
   *  180 and 270 degrees rotation. 180 degrees rotation is performed
   *  in-place by simply reversing the image data, which is a very
   *  fast operation. 90 and 270 degrees rotation are performed using
   *  a temporary buffer and a somewhat more complicated algorithm,
   *  which makes them slower.
   *
   *  Note that to the caller, all rotations will seem as they are
   *  performed in-place.
   *
   * Parameters:
   * 
   *   map - the image map/data to rotate
   *   cnt - current thread's context structure
   *   
   * Returns: 
   *
   *   0  - success 
   *   -1 - failure (rare, shouldn't happen)
   */
  int rotate_map(struct context *cnt, unsigned char *map);
  
  #endif
  