legoEv3/evdev/events.py

# encoding: utf-8

'''
This module provides the :class:`InputEvent` class, which closely
resembles the ``input_event`` struct defined in ``linux/input.h``:

.. code-block:: c

    struct input_event {
        struct timeval time;
        __u16 type;
        __u16 code;
        __s32 value;
    };

This module also defines several :class:`InputEvent` sub-classes that
know more about the different types of events (key, abs, rel etc). The
:data:`event_factory` dictionary maps event types to these classes.

Assuming you use the :func:`evdev.util.categorize()` function to
categorize events according to their type, adding or replacing a class
for a specific event type becomes a matter of modifying
:data:`event_factory`.

All classes in this module have reasonable ``str()`` and ``repr()``
methods::

    >>> print(event)
    event at 1337197425.477827, code 04, type 04, val 458792
    >>> print(repr(event))
    InputEvent(1337197425L, 477827L, 4, 4, 458792L)

    >>> print(key_event)
    key event at 1337197425.477835, 28 (KEY_ENTER), up
    >>> print(repr(key_event))
    KeyEvent(InputEvent(1337197425L, 477835L, 1, 28, 0L))
'''

# event type descriptions have been taken mot-a-mot from:
# http://www.kernel.org/doc/Documentation/input/event-codes.txt

from evdev.ecodes import keys, KEY, SYN, REL, ABS, EV_KEY, EV_REL, EV_ABS, EV_SYN


class InputEvent(object):
    '''A generic input event.'''

    __slots__ = 'sec', 'usec', 'type', 'code', 'value'

    def __init__(self, sec, usec, type, code, value):
        #: Time in seconds since epoch at which event occurred.
        self.sec = sec

        #: Microsecond portion of the timestamp.
        self.usec = usec

        #: Event type - one of ``ecodes.EV_*``.
        self.type = type

        #: Event code related to the event type.
        self.code = code

        #: Event value related to the event type.
        self.value = value

    def timestamp(self):
        '''Return event timestamp as a float.'''
        return self.sec + (self.usec / 1000000.0)

    def __str__(s):
        msg = 'event at {:f}, code {:02d}, type {:02d}, val {:02d}'
        return msg.format(s.timestamp(), s.code, s.type, s.value)

    def __repr__(s):
        msg = '{}({!r}, {!r}, {!r}, {!r}, {!r})'
        return msg.format(s.__class__.__name__,
                          s.sec, s.usec, s.type, s.code, s.value)


class KeyEvent(object):
    '''An event generated by a keyboard, button or other key-like devices.'''

    key_up   = 0x0
    key_down = 0x1
    key_hold = 0x2

    __slots__ = 'scancode', 'keycode', 'keystate', 'event'

    def __init__(self, event):
        if event.value == 0:
            self.keystate = KeyEvent.key_up
        elif event.value == 2:
            self.keystate = KeyEvent.key_hold
        elif event.value == 1:
            self.keystate = KeyEvent.key_down

        self.keycode  = keys[event.code]  # :todo:
        self.scancode = event.code

        #: Reference to an :class:`InputEvent` instance.
        self.event = event

    def __str__(self):
        try:
            ks = ('up', 'down', 'hold')[self.keystate]
        except IndexError:
            ks = 'unknown'

        msg = 'key event at {:f}, {} ({}), {}'
        return msg.format(self.event.timestamp(),
                          self.scancode, self.keycode, ks)

    def __repr__(s):
        return '{}({!r})'.format(s.__class__.__name__, s.event)


class RelEvent(object):
    '''A relative axis event (e.g moving the mouse 5 units to the left).'''

    __slots__ = 'event'

    def __init__(self, event):
        #: Reference to an :class:`InputEvent` instance.
        self.event = event

    def __str__(self):
        msg = 'relative axis event at {:f}, {} '
        return msg.format(self.event.timestamp(), REL[self.event.code])

    def __repr__(s):
        return '{}({!r})'.format(s.__class__.__name__, s.event)


class AbsEvent(object):
    '''An absolute axis event (e.g the coordinates of a tap on a touchscreen).'''

    __slots__ = 'event'

    def __init__(self, event):
        #: Reference to an :class:`InputEvent` instance.
        self.event = event

    def __str__(self):
        msg = 'absolute axis event at {:f}, {} '
        return msg.format(self.event.timestamp(), ABS[self.event.code])

    def __repr__(s):
        return '{}({!r})'.format(s.__class__.__name__, s.event)


class SynEvent(object):
    '''
    A synchronization event. Synchronization events are used as
    markers to separate event. Used as markers to separate
    events. Events may be separated in time or in space, such as with
    the multitouch protocol.
    '''

    __slots__ = 'event'

    def __init__(self, event):
        #: Reference to an :class:`InputEvent` instance.
        self.event = event

    def __str__(self):
        msg = 'synchronization event at {:f}, {} '
        return msg.format(self.event.timestamp(), SYN[self.event.code])

    def __repr__(s):
        return '{}({!r})'.format(s.__class__.__name__, s.event)


#: A mapping of event types to :class:`InputEvent` sub-classes. Used
#: by :func:`evdev.util.categorize()`
event_factory = {
    EV_KEY: KeyEvent,
    EV_REL: RelEvent,
    EV_ABS: AbsEvent,
    EV_SYN: SynEvent,
}


__all__ = ('InputEvent', 'KeyEvent', 'RelEvent', 'SynEvent',
           'AbsEvent', 'event_factory')