fli_bmp_dirty_from - Man Page

#include <allegro.h>

extern int fli_bmp_dirty_from;

extern int fli_bmp_dirty_to;

These variables are set by next_fli_frame() to indicate which part of the  fli_bitmap has changed since the last call to reset_fli_variables(). If  fli_bmp_dirty_from is greater than fli_bmp_dirty_to, the bitmap has not  changed, otherwise lines fli_bmp_dirty_from to fli_bmp_dirty_to  (inclusive) have altered. You can use these when copying the fli_bitmap  onto the screen, to avoid moving data unnecessarily. Example:

   if (fli_bmp_dirty_from <= fli_bmp_dirty_to)
      blit(fli_bitmap, screen, 0, fli_bmp_dirty_from,
           0, fli_bmp_dirty_from, fli_bitmap->w,
           fli_bmp_dirty_to - fli_bmp_dirty_from + 1);

fli_bitmap(3), reset_fli_variables(3)

fli_bitmap(3), reset_fli_variables(3).

The man page fli_bmp_dirty_to(3) is an alias of fli_bmp_dirty_from(3).