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keyboard_callback(3)		Allegro	manual		  keyboard_callback(3)

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  un-
       changed,	 return	zero to	cause the key to be ignored, or	return a modi-
       fied value to change what readkey() will	later return. This routine ex-
       ecutes  in  an interrupt	context, so it must be in locked memory. Exam-
       ple:

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

Allegro				 version 4.4.2		  keyboard_callback(3)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO

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