1 =================
2 Keyboard notifier
3 =================
4
5 One can use register_keyboard_notifier to get
6 events (see kbd_keycode() function for details
7 keyboard_notifier_param (see <linux/keyboard.h
8
9 - 'vc' always provide the VC for which the key
10 - 'down' is 1 for a key press event, 0 for a k
11 - 'shift' is the current modifier state, mask
12 - 'ledstate' is the current LED state;
13 - 'value' depends on the type of event.
14
15 - KBD_KEYCODE events are always sent before ot
16 - KBD_UNBOUND_KEYCODE events are sent if the k
17 value is the keycode.
18 - KBD_UNICODE events are sent if the keycode -
19 unicode character. value is the unicode valu
20 - KBD_KEYSYM events are sent if the keycode ->
21 non-unicode character. value is the keysym.
22 - KBD_POST_KEYSYM events are sent after the tr
23 That permits one to inspect the resulting LE
24
25 For each kind of event but the last, the callb
26 order to "eat" the event: the notify loop is s
27 dropped.
28
29 In a rough C snippet, we have::
30
31 kbd_keycode(keycode) {
32 ...
33 params.value = keycode;
34 if (notifier_call_chain(KBD_KEYCODE,&p
35 || !bound) {
36 notifier_call_chain(KBD_UNBOUN
37 return;
38 }
39
40 if (unicode) {
41 param.value = unicode;
42 if (notifier_call_chain(KBD_UN
43 return;
44 emit unicode;
45 return;
46 }
47
48 params.value = keysym;
49 if (notifier_call_chain(KBD_KEYSYM,&pa
50 return;
51 apply keysym;
52 notifier_call_chain(KBD_POST_KEYSYM,&p
53 }
54
55 .. note:: This notifier is usually called from
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