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key(3)

NAME

key – Array of flags indicating key state. Allegro game programming library.

SYNOPSIS

#include <allegro.h>

extern volatile char key[KEY_MAX];

DESCRIPTION

Array of flags indicating the state of each key, ordered by scancode. Wherever possible these values will be updated asynchronously, but if keyboard_needs_poll() returns TRUE, you must manually call poll_keyboard() to update them with the current input state. The scancodes are defined in allegro/keyboard.h as a series of KEY_* constants (and are also listed below). For example, you could write:


if (key[KEY_SPACE])
    printf("Space is pressed
");

Note that the array is supposed to represent which keys are physically held down and which keys are not, so it is semantically read-only.

These are the keyboard scancodes:

   KEY_A ... KEY_Z,
   KEY_0 ... KEY_9,
   KEY_0_PAD ... KEY_9_PAD,
   KEY_F1 ... KEY_F12,

KEY_ESC, KEY_TILDE, KEY_MINUS, KEY_EQUALS,
KEY_BACKSPACE, KEY_TAB, KEY_OPENBRACE, KEY_CLOSEBRACE,
KEY_ENTER, KEY_COLON, KEY_QUOTE, KEY_BACKSLASH,
KEY_BACKSLASH2, KEY_COMMA, KEY_STOP, KEY_SLASH,
KEY_SPACE,


KEY_INSERT, KEY_DEL, KEY_HOME, KEY_END, KEY_PGUP,
KEY_PGDN, KEY_LEFT, KEY_RIGHT, KEY_UP, KEY_DOWN,


KEY_SLASH_PAD, KEY_ASTERISK, KEY_MINUS_PAD,
KEY_PLUS_PAD, KEY_DEL_PAD, KEY_ENTER_PAD,


KEY_PRTSCR, KEY_PAUSE,


KEY_ABNT_C1, KEY_YEN, KEY_KANA, KEY_CONVERT, KEY_NOCONVERT,
KEY_AT, KEY_CIRCUMFLEX, KEY_COLON2, KEY_KANJI,


KEY_LSHIFT, KEY_RSHIFT,
KEY_LCONTROL, KEY_RCONTROL,
KEY_ALT, KEY_ALTGR,
KEY_LWIN, KEY_RWIN, KEY_MENU,
KEY_SCRLOCK, KEY_NUMLOCK, KEY_CAPSLOCK


KEY_EQUALS_PAD, KEY_BACKQUOTE, KEY_SEMICOLON, KEY_COMMAND

Finally, you may notice an `odd’ behaviour of the KEY_PAUSE key. This key only generates an interrupt when it is pressed, not when it is released. For this reason, Allegro pretends the pause key is a `state’ key, which is the only way to make it usable.

SEE ALSO

install_keyboard(3), poll_keyboard(3), key_shifts(3)

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