Input subsystem

These are the devices that receive key commands from some external source and route them to your applications. At the input system core, there’s InputListener. It receives key events from drivers you use and routes them to currently active application.

Available input drivers:

InputListener

The i variable you have supplied by main.py load_app() in your applications is an InputListener instance. It’s operating on key names, such as “KEY_ENTER” or “KEY_UP”. You can assign callback once a keypress with a matching keyname is received, which is as simple as i.set_callback(key_name, callback). You can also set a dictionary of "keyname":callback_function mappings, this would be called a keymap.

class input.input.InputListener(drivers, keymap=None)[source]

A class which listens for input device events and calls corresponding callbacks if set

__init__(drivers, keymap=None)[source]

Init function for creating KeyListener object. Checks all the arguments and sets keymap if supplied.

atexit()[source]

Exits driver (if necessary) if something wrong happened or pyLCI exits. Also, stops the listener

check_special_callback(key_name)[source]

Raises exceptions upon setting of a special callback on a reserved/taken keyname

clear_keymap()[source]

Removes all the callbacks set

event_loop(index)[source]

Blocking event loop which just calls callbacks in the keymap once corresponding keys are received in the self.queue.

listen()[source]

Start event_loop in a thread. Nonblocking.

receive_key(key)[source]

This is the method that receives keypresses from drivers and puts them into self.queue for self.event_loop to receive

remove_callback(key_name)[source]

Removes a single callback of the listener

remove_streaming()[source]

Removes a callback for streaming key events, if previously set by any app/UI element.

replace_keymap_entries(keymap)[source]

Sets all the callbacks supplied, not removing previously set but overwriting those with same keycodes

set_callback(key_name, callback)[source]

Sets a single callback of the listener

set_keymap(keymap)[source]

Sets all the callbacks supplied, removing the previously set keymap completely

set_maskable_callback(key_name, callback)[source]

Sets a single maskable callback of the listener. Raises CallbackException if the callback is one of the reserved keys or already is in maskable/nonmaskable keymap.

A maskable callback is global (never cleared) and will be called upon a keypress unless a callback for the same keyname is already set in keymap.

set_nonmaskable_callback(key_name, callback)[source]

Sets a single nonmaskable callback of the listener. Raises CallbackException if the callback is one of the reserved keys or already is in maskable/nonmaskable keymap.

A nonmaskable callback is global (never cleared) and will be called upon a keypress even if a callback for the same keyname is already set in keymap (callback from the keymap won’t be called).

set_streaming(callback)[source]

Sets a callback for streaming key events. The callback will be called with key_name as first argument but should support arbitrary number of positional arguments if compatibility with future versions is desired.

stop_listen()[source]

This sets a flag for event_loop to stop. It also calls a stop method of the input driver InputListener is using.

Note

In v1.0 architecture, there’s a single InputListener instance shared among all applications, so when you set some callbacks for your application and then exit it or execute your application’s menu element, there’s a very good chance your callbacks won’t be there anymore once you return. You won’t need to think about it unless you’re setting InputListener yourself - mostly it’s taken care of by UI objects, which set the keymaps themselves themselves (for example, Menu UI element sets the callbacks each time a menu is activated and each time a menu element callback execution is finished (because a Menu can’t be sure whatever got called by the callback didn’t set some of callbacks some other way, say, the element’s callback was activating a nested menu.)

If you do set callbacks/keymap yourself (very useful for making your own UI elements, or for applications needing custom keybindings), it’s important to remember that you need to stop InputListener before and start it again afterwards, since the changes do not take place until that’s done. For example, this is how you would set your own callback:

i.stop_listen()
i.clear_keymap() #Useful because there might be callbacks left from whatever your function was called by
#... Set your callbacks
i.set_callback("KEY_ENTER", my_function)
i.listen()

Glue logic functions

Warning

Not for user interaction, are called by main.py, which is pyLCI launcher.

input.input.init()[source]

This function is called by main.py to read the input configuration, pick the corresponding drivers and initialize InputListener.

It also sets listener globals of input module with driver and listener respectively, as well as registers listener.stop() function to be called when script exits since it’s in a blocking non-daemon thread.