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54 lines
1.8 KiB
54 lines
1.8 KiB
================= |
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Keyboard notifier |
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================= |
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One can use register_keyboard_notifier to get called back on keyboard |
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events (see kbd_keycode() function for details). The passed structure is |
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keyboard_notifier_param: |
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- 'vc' always provide the VC for which the keyboard event applies; |
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- 'down' is 1 for a key press event, 0 for a key release; |
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- 'shift' is the current modifier state, mask bit indexes are KG_*; |
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- 'value' depends on the type of event. |
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- KBD_KEYCODE events are always sent before other events, value is the keycode. |
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- KBD_UNBOUND_KEYCODE events are sent if the keycode is not bound to a keysym. |
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value is the keycode. |
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- KBD_UNICODE events are sent if the keycode -> keysym translation produced a |
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unicode character. value is the unicode value. |
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- KBD_KEYSYM events are sent if the keycode -> keysym translation produced a |
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non-unicode character. value is the keysym. |
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- KBD_POST_KEYSYM events are sent after the treatment of non-unicode keysyms. |
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That permits one to inspect the resulting LEDs for instance. |
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For each kind of event but the last, the callback may return NOTIFY_STOP in |
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order to "eat" the event: the notify loop is stopped and the keyboard event is |
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dropped. |
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In a rough C snippet, we have:: |
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kbd_keycode(keycode) { |
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... |
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params.value = keycode; |
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if (notifier_call_chain(KBD_KEYCODE,¶ms) == NOTIFY_STOP) |
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|| !bound) { |
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notifier_call_chain(KBD_UNBOUND_KEYCODE,¶ms); |
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return; |
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} |
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if (unicode) { |
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param.value = unicode; |
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if (notifier_call_chain(KBD_UNICODE,¶ms) == NOTIFY_STOP) |
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return; |
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emit unicode; |
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return; |
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} |
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params.value = keysym; |
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if (notifier_call_chain(KBD_KEYSYM,¶ms) == NOTIFY_STOP) |
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return; |
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apply keysym; |
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notifier_call_chain(KBD_POST_KEYSYM,¶ms); |
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} |
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.. note:: This notifier is usually called from interrupt context.
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