keyboard_callback(3alleg4) linux man page | unix.com

keyboard_callback(3alleg4)					  Allegro manual					keyboard_callback(3alleg4)

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(3alleg4), readkey(3alleg4), ureadkey(3alleg4), keyboard_ucallback(3alleg4), keyboard_lowlevel_callback(3alleg4)

Allegro 							   version 4.4.2					keyboard_callback(3alleg4)