Provided by: liballegro-doc_4.2.2-3_all bug

NAME

       keyboard_callback  -  User  specified  keyboard callback handler. Allegro game programming
       library.

SYNOPSIS

       #include <allegro.h>

       extern int (*keyboard_callback)(int key);

DESCRIPTION

       If set, this function is called by the keyboard handler in response to every keypress.  It
       is  passed  a  copy  of the value that is about to be added into the input buffer, and can
       either return this value unchanged, return zero to cause the key to be ignored, or  return
       a  modified  value to change what readkey() will later return. This routine executes in an
       interrupt context, so it must be in locked memory. Example:

          int enigma_scrambler(int key)
          {
             /* Add one to both the scancode and ascii values. */
             return (((key >> 8) + 1)
          }
          END_OF_FUNCTION(enigma_scrambler)

          ...

             install_timer();
             LOCK_FUNCTION(enigma_scrambler);
             install_keyboard();
             keyboard_callback = enigma_scrambler;

       Note that this callback will be ignored if you also set the unicode keyboard callback.

SEE ALSO

       install_keyboard(3alleg), readkey(3alleg),  ureadkey(3alleg),  keyboard_ucallback(3alleg),
       keyboard_lowlevel_callback(3alleg)