Commit | Line | Data |
---|---|---|
e32f7ee8 ST |
1 | Keyboard notifier |
2 | ||
3 | One can use register_keyboard_notifier to get called back on keyboard | |
4 | events (see kbd_keycode() function for details). The passed structure is | |
5 | keyboard_notifier_param: | |
6 | ||
7 | - 'vc' always provide the VC for which the keyboard event applies; | |
8 | - 'down' is 1 for a key press event, 0 for a key release; | |
9 | - 'shift' is the current modifier state, mask bit indexes are KG_*; | |
10 | - 'value' depends on the type of event. | |
11 | ||
12 | - KBD_KEYCODE events are always sent before other events, value is the keycode. | |
13 | - KBD_UNBOUND_KEYCODE events are sent if the keycode is not bound to a keysym. | |
14 | value is the keycode. | |
15 | - KBD_UNICODE events are sent if the keycode -> keysym translation produced a | |
16 | unicode character. value is the unicode value. | |
17 | - KBD_KEYSYM events are sent if the keycode -> keysym translation produced a | |
18 | non-unicode character. value is the keysym. | |
19 | - KBD_POST_KEYSYM events are sent after the treatment of non-unicode keysyms. | |
20 | That permits one to inspect the resulting LEDs for instance. | |
21 | ||
22 | For each kind of event but the last, the callback may return NOTIFY_STOP in | |
23 | order to "eat" the event: the notify loop is stopped and the keyboard event is | |
24 | dropped. | |
25 | ||
26 | In a rough C snippet, we have: | |
27 | ||
28 | kbd_keycode(keycode) { | |
29 | ... | |
30 | params.value = keycode; | |
31 | if (notifier_call_chain(KBD_KEYCODE,¶ms) == NOTIFY_STOP) | |
32 | || !bound) { | |
33 | notifier_call_chain(KBD_UNBOUND_KEYCODE,¶ms); | |
34 | return; | |
35 | } | |
36 | ||
37 | if (unicode) { | |
38 | param.value = unicode; | |
39 | if (notifier_call_chain(KBD_UNICODE,¶ms) == NOTIFY_STOP) | |
40 | return; | |
41 | emit unicode; | |
42 | return; | |
43 | } | |
44 | ||
45 | params.value = keysym; | |
46 | if (notifier_call_chain(KBD_KEYSYM,¶ms) == NOTIFY_STOP) | |
47 | return; | |
48 | apply keysym; | |
49 | notifier_call_chain(KBD_POST_KEYSYM,¶ms); | |
50 | } | |
51 | ||
52 | NOTE: This notifier is usually called from interrupt context. |