libevdev package

Submodules

libevdev.const module

class EvdevBit

Bases: object

Base class representing an evdev bit, comprised of a name and a value. These two properties are guaranteed to exist on anything describing an event code, event type or input property that comes out of libevdev:

>>> print(libevdev.EV_ABS.name)
EV_ABS
>>> print(libevdev.EV_ABS.value)
3
>>> print(libevdev.EV_SYN.SYN_REPORT.name)
SYN_REPORT
>>> print(libevdev.EV_SYN.SYN_REPORT.value)
0
>>> print(libevdev.INPUT_PROP_DIRECT.name)
INPUT_PROP_DIRECT
>>> print(libevdev.INPUT_PROP_DIRECT.value)
1
value

The numeric value of the event code

name

The string name of this event code

class EventCode

Bases: libevdev.const.EvdevBit

Warning

Do not instantiate an object of this class, all objects you’ll ever need are already present in the libevdev namespace. Use evbit() to get an EventCode from numerical or string values.

A class representing an evdev event code, e.g. libevdev.EV_ABS.ABS_X. To use a EventCode, use the namespaced name directly:

>>> print(libevdev.EV_ABS.ABS_X)
ABS_X:0
>>> print(libevdev.EV_ABS.ABS_Y)
ABS_X:1
>>> code = libevdev.EV_REL.REL_X
>>> print(code.type)
EV_REL:2
value

The numeric value of the event code

name

The string name of this event code

type

The EventType for this event code

class EventType

Bases: libevdev.const.EvdevBit

Warning

Do not instantiate an object of this class, all objects you’ll ever need are already present in the libevdev namespace. Use evbit() to get an EventType from numerical or string values.

A class represending an evdev event type (e.g. EV_ABS). All event codes within this type are available as class constants:

>>> print(libevdev.EV_ABS)
EV_ABS:3
>>> print(libevdev.EV_ABS.ABS_X)
ABS_X:0
>>> print(libevdev.EV_ABS.max)
63
>>> print(libevdev.EV_ABS.ABS_MAX)
63
>>> for code in libevdev.EV_ABS.codes[:3]:
...     print(code)
...
ABS_X:0
ABS_Y:1
ABS_Z:2
value

The numeric value of the event type

name

The string name of this event type

codes

A list of EventCode objects for this type

max

The maximum event code permitted in this type as integer

class InputProperty

Bases: libevdev.const.EvdevBit

Warning

Do not instantiate an object of this class, all objects you’ll ever need are already present in the libevdev namespace. Use propbit() to get an InputProperty from numerical or string values.

A class representing an evdev input property:

>>> print(libevdev.INPUT_PROP_DIRECT)
INPUT_PROP_DIRECT:1
value

The numeric value of the property

name

The string name of this property

evbit(evtype, evcode=None)

Takes an event type and an (optional) event code and returns the Enum representing that type or code, whichever applies. For example:

>>> print(libevdev.evbit(0))
EV_SYN:0

>>> print(libevdev.evbit(2))
EV_REL:2

>>> print(libevdev.evbit(2, 1))
REL_Y:1

>>> print(libevdev.evbit(3, 4))
ABS_RY:4

>>> print(libevdev.evbit('EV_ABS'))
EV_ABS:3

>>> print(libevdev.evbit('EV_ABS', 'ABS_X'))
ABS_X:0

A special case is the lookup of an string-based event code without the type. Where the string identifier is unique, this will return the right value.

>>> print(libevdev.evbit('ABS_X'))
ABS_X:0

The return value can be used in the libevdev API wherever an EventCode or EventType is expected.

Notable behavior for invalid types or names:

  • If the type does not exist, this function returns None
  • If the type exists but the event code’s numeric value does not have a symbolic name (and is within the allowed max of the type), this function returns a valid event code
  • If the code is outside the allowed maximum for the given type, this function returns None
  • If the type name exists but the string value is not a code name, this function returns None

Examples for the above behaviour:

>>> print(libevdev.evbit(8))
None
>>> print(libevdev.evbit('INVALID'))
None
>>> print(libevdev.evbit('EV_ABS', 62))
ABS_3E:62
>>> print(libevdev.evbit('EV_ABS', 5000))
None
>>> print(libevdev.evbit('EV_ABS', 'INVALID'))
None
Parameters:
  • evtype – the numeric value or string identifying the event type
  • evcode – the numeric value or string identifying the event code
Returns:

An event code value representing the code

Return type:

EventCode or EventType

propbit(prop)

Takes a property value and returns the InputProperty representing that property:

>>> print(libevdev.propbit(0))
INPUT_PROP_POINTER:0
>>> print(libevdev.propbit('INPUT_PROP_POINTER'))
INPUT_PROP_POINTER:0
>>> print(libevdev.propbit(1000))
None
>>> print(libevdev.propbit('Invalid'))
None
Parameters:prop – the numeric value or string identifying the property
Returns:the converted InputProperty or None if it does not exist
Return type:InputProperty

libevdev.device module

class Device(fd=None)

Bases: object

This class represents an evdev device backed by libevdev. The device may represent a real device in the system or a constructed device where the caller supplies all properties of the device.

If a file is given, the device initializes from that file, otherwise the device is uninitialized and needs to be set up by the caller:

fd = open("/dev/input/event0", "rb")
l = libevdev.Device(fd)
# l now represents the device on event0

l2 = libevdev.Device()
l2.name = "test device"
l2.enable(libevdev.EV_REL.REL_X)
# l2 is an unbound device with the REL_X bit set

Note that if a device is constructed manually, the fd of the device is always None.

Note

The device is always set to CLOCK_MONOTONIC.

Parameters:fd (A file-like object) – fd pointing to a /dev/input/eventX event node
absinfo

Query the device’s absinfo for the given event code. This attribute can both query and modify the InputAbsInfo values of this device:

>>> ai = d.absinfo[libevdev.EV_ABS.ABS_X]
>>> print(f'Resolution is {ai.resolution}')
Resolution is 33
>>> ai = d.absinfo[libevdev.EV_ABS.ABS_Z]
>>> print(ai)
None

The returned object is a dict-like object that only accepts event codes of type EV_ABS as keys. No other operation than key-based access is supported.

When used as a setter, the provided InputAbsInfo becomes the new absinfo of this axis:

>>> ai = d.absinfo[libevdev.EV_ABS.ABS_X]
>>> print(f'Resolution is {ai.resolution}')
Resolution is 33
>>> ai.resolution = 45
>>> d.absinfo[libevdev.EV_ABS.ABS_X] = ai
>>> ai = d.absinfo[libevdev.EV_ABS.ABS_X]
>>> print(f'Resolution is now {ai.resolution}')
Resolution is now 45

When used as a setter, any attribute of InputAbsInfo that is None is ignored:

>>> ai = InputAbsInfo(resolution=72)
>>> d.absinfo[libevdev.EV_ABS.ABS_X] = ai
>>> ai = d.absinfo[libevdev.EV_ABS.ABS_X]
>>> print(f'Resolution is now {ai.resolution}')
Resolution is now 72

Warning

Setting the absinfo for a non-existing EV_ABS code is invalid. Use enable() instead.

Returns:an class:InputAbsInfo struct or None if the device does not have the event code
Raises:InvalidArgumentException when trying to set an axis that is not enabled.
create_uinput_device(uinput_fd=None)

Creates and returns a new Device based on this libevdev device. The new device is equivalent to one created with libevdev.Device(), i.e. it is one that does not have a file descriptor associated.

To create a uinput device from an existing device:

fd = open('/dev/input/event0', 'rb')
d = libevdev.Device(fd)
d.name = 'duplicated device'
d.create_uinput_device()
# d is now a duplicate of the event0 device with a custom name
fd.close()

Or to create a new device from scratch:

d = libevdev.Device()
d.name = 'test device'
d.enable(libevdev.EV_KEY.BTN_LEFT)
d.create_uinput_device()
# d is now a device with a single button
Parameters:uinput_fd – A file descriptor to the /dev/input/uinput device. If None, the device is opened and closed automatically.
Raises:OSError
current_slot
Returns:the current slot on this device or None if this device does not support slots
Note:Read-only
devnode

Returns the device node for this device. The device node is None if this device has not been created as uinput device.

disable(event_code)

Disable the given event type or event code on this device. If the device does not support this type or code, this function does nothing. Otherwise, all future events from this device that match this type or code will be discarded:

>>> d.disable(libevdev.EV_ABS)
# All EV_ABS events are filtered now
>>> d.disable(libevdev.EV_KEY.BTN_LEFT)
# All BTN_LEFt events are filtered now

To re-enable an event type or code, use enable()

Parameters:event_code (EventType or EventCode) – the event type or code
driver_version
Returns:the device’s driver version
enable(event_code, data=None)

Enable an event type or event code on this device, even if not supported by this device. If event_code is an EventType, that type is enabled and data is ignored.

If event_code is one of libevdev.EV_ABS.ABS_*, then data must be a InputAbsInfo. Any unset fields of the InputAbsInfo are replaced with 0, i.e. the following example is valid and results in a fuzz/flat/resolution of zero:

ctx = libevdev.Device()
abs = InputAbsInfo(minimum=0, maximum=100)
ctx.enable(libevdev.EV_ABS.ABS_X, data)

If event_code is one of libevdev.EV_REP.REP_, then data must be an integer.

If event_code is one of libevdev.INPUT_PROP_, then the given input property is enabled.

Parameters:
  • event_code (EventCode or EventType) – the event code
  • data – if event_code is not None, data points to the code-specific information.
evbits

Returns a dict with all supported event types and event codes, in the form of:

{
  libevdev.EV_ABS: [libevdev.EV_ABS.ABS_X, ...],
  libevdev.EV_KEY: [libevdev.EV_KEY.BTN_LEFT, ...],
}
events()

Returns an iterable with currently pending events.

Event processing should look like this:

fd = open("/dev/input/event0", "rb")
ctx = libevdev.Device(fd)

while True:
    for e in ctx.events():
        print(e):

This function detects if the file descriptor is in blocking or non-blocking mode and adjusts its behavior accordingly. If the file descriptor is in nonblocking mode and no events are available, this function returns immediately. If the file descriptor is blocking, this function blocks if there are no events available.

Returns:an iterable with the currently pending events
fd

This fd represents the file descriptor to this device, if any. If no fd was provided in the constructor, None is returned. If the device was used to create a uinput device, None is returned.

The fd may only be changed if it was not initially None and then it overwrites the file object provided in the constructor (or a previous call to this function). The new file object becomes the object referencing this device, further events are polled from that file.

Warning

A device initialized without a file descriptor may not change its fd.

Note that libevdev does not synchronize the device and relies on the caller to ensure that the new file object points to the same device as this context. If the underlying device changes, the behavior is undefined.

Raises:InvalidFileError - the file is invalid or this device does not allow a file to be set
grab()

Exclusively grabs the device, preventing events from being seen by anyone else. This includes in-kernel consumers of the events (e.g. for rfkill) and should be used with care.

A grab is valid until the file descriptor is closed or until ungrab() is called, whichever happens earlier. libevdev re-issues the grab on the device after changing the fd. If the original file descriptor is still open when changing the fd on the device, re-issuing the grab will fail silently:

fd1 = open("/dev/input/event0", "rb")
d = libevdev.Device(fd1)
d.grab()
# device is now exclusively grabbed

fd.close()
fd2 = open("/dev/input/event0", "rb")
d.fd = fd2
# device is now exclusively grabbed

fd3 = open("/dev/input/event0", "rb")
d.fd = fd3
# ERROR: fd2 is still open and the grab fails
has(evcode)
Parameters:evcode (EventType or EventCode) – the event type or event code
Returns:True if the device has the type and/or code, False otherwise
has_property(prop)
Parameters:prop – a property
Returns:True if the device has the property, False otherwise
id
Returns:A dict with the keys ‘bustype’, ‘vendor’, ‘product’, ‘version’.

When used as a setter, only existing keys are applied to the device. For example, to update the product ID only:

ctx = Device()
id["property"] = 1234
ctx.id = id
name
Returns:the device name
num_slots
Returns:the number of slots on this device or None if this device does not support slots
Note:Read-only
phys
Returns:the device’s kernel phys or None.
properties

Returns a list of all supported input properties

send_events(events)

Send the list of InputEvent events through this device. All events must have a valid EventCode and value, the timestamp in the event is ignored and the kernel fills in its own timestamp.

This function may only be called on a uinput device, not on a normal device.

Warning

an event list must always be terminated with a libevdev.EV_SYN.SYN_REPORT event or the kernel may delay processing.

Parameters:events – a list of InputEvent events
slots

Returns a tuple with the available slots, each of which contains a wrapper object to access a slot value:

>>> d = libevdev.Device(fd)
>>> print(d.slots[0][libevdev.EV_ABS.ABS_MT_POSITION_X])
1000
>>> print(d.slots[0][libevdev.EV_ABS.ABS_MT_POSITION_Y])
500
>>> print(d.slots[1][libevdev.EV_ABS.ABS_MT_POSITION_X])
200
>>> print(d.slots[1][libevdev.EV_ABS.ABS_MT_POSITION_Y])
300

Alternatively, the tuple can be iterated on:

xcode = libevdev.EV_ABS.ABS_MT_POSITION_X
ycode = libevdev.EV_ABS.ABS_MT_POSITION_Y

for s in d.slots:
     position = (s[xcode], s[ycode])

The only values available for each slot are the ones in the libevdev.EV_ABS.ABS_MT_* range (but not libevdev.EV_ABS.ABS_MT_SLOT).

sync(force=False)

Returns an iterator with events pending to re-sync the caller’s view of the device with the one from libevdev.

Parameters:force – if set, the device forces an internal sync. This is required after changing the fd of the device when the device state may have changed while libevdev was not processing events.
sync_absinfo_to_kernel(code)

Synchronizes our view of an absinfo axis to the kernel, thus updating the the device for every other client. This function should be used with care. Not only does it change the kernel device and thus may affect the behavior of other processes but it is racy: any client that has this device node open already may never see the updates.

To use this function, update the absinfo for the desired axis first:

>>> fd = open('/dev/input/event0', 'rb')
>>> d = libevdev.Device(fd)
>>> ai = InputAbsInfo(resolution=72)
>>> d.absinfo[libevdev.EV_ABS.ABS_X] = ai
>>> d.sync_absinfo_to_kernel(libevdev.EV_ABS.ABS_X)
syspath

Returns the syspath for this device. The syspath is None if this device has not been created as uinput device.

ungrab()

Removes an exclusive grabs on the device, see grab().

uniq
Returns:the device’s uniq string or None
value

Returns the current value for a given event code or None where the event code does not exist on the device:

>>> d = libevdev.Device(fd)
>>> print(d.value[libevdev.EV_ABS.ABS_X])
1024
>>> print(d.value[libevdev.EV_ABS.ABS_Y])
512
>>> print(d.value[libevdev.EV_ABS.ABS_Z])
None

The returned object is a dict-like object that only accepts event codes as keys. No other operation than key-based access is supported.

The default value for all codes is 0. State-less axes like the EV_REL range always return 0 for all supported event codes.

exception DeviceGrabError

Bases: Exception

A device grab failed to be issued. A caller must not assume that it has exclusive access to the events on the device.

exception EventsDroppedException

Bases: Exception

Notification that the device has dropped events, raised in response to a EV_SYN SYN_DROPPED event.

This exception is raised AFTER the EV_SYN, SYN_DROPPED event has been passed on. If SYN_DROPPED events are processed manually, then this exception can be ignored.

Once received (or in response to a SYN_DROPPED event) a caller should call device.sync() and process the events accordingly (if any).

Example:

fd = open("/dev/input/event0", "rb")
ctx = libevdev.Device(fd)

while True:
    try:
        for e in ctx.events():
            print(e):
    except EventsDroppedException:
        print('State lost, re-synching:')
        for e in ctx.sync():
            print(e)
class InputAbsInfo(minimum=None, maximum=None, fuzz=None, flat=None, resolution=None, value=None)

Bases: object

A class representing the struct input_absinfo for a given EV_ABS code.

Any of the attributes may be set to None, those that are None are simply ignored by libevdev.

minimum

the minimum value of this axis

Property minimum:
 the minimum value for this axis
Property maximum:
 the maximum value for this axis
Property fuzz:the fuzz value for this axis
Property flat:the flat value for this axis
Property resolution:
 the resolution for this axis
Property value:the current value of this axis
exception InvalidArgumentException(msg=None)

Bases: Exception

A function was called with an invalid argument. This indicates a bug in the calling program.

message

A human-readable error message

exception InvalidFileError

Bases: Exception

A file provided is not a valid file descriptor for libevdev or this device must not have a file descriptor

libevdev.event module

class InputEvent(code, value=None, sec=0, usec=0)

Bases: object

Represents one input event of type struct input_event as defined in linux/input.h and returned by libevdev_next_event().

Comparison between events can be done via the matches() function or by comparing two input events. Two events match when their most precise attribute match and all other attributes are None:

>>> e = InputEvent(libevdev.EV_REL.REL_X, value=1)
>>> e == InputEvent(libevdev.EV_REL)
True
>>> e == InputEvent(libevdev.EV_ABS)
True
>>> e == InputEvent(libevdev.EV_REL.REL_X)
True
>>> e == InputEvent(libevdev.EV_REL.REL_Y)
False
>>> e == InputEvent(libevdev.EV_REL.REL_X, value=1)
True
>>> e == InputEvent(libevdev.EV_REL.REL_X, value=2)
False
code

The EventCode or EventType for this input event

value

The (optional) value for the event’s axis

sec

The timestamp, seconds

usec

The timestamp, microseconds

code
Returns:the EventCode for this event or None
Return type:EventCode
matches(code, value=None)
Parameters:
  • code (EventType or EventCode) – the event type or code
  • value – optional, the event value
Returns:

True if the type matches this event’s type and this event’s code matches the given code (if any) and this event’s value matches the given value (if any)

Check if an event matches a given event type and/or code. The following invocations show how to match on an event type, an event code and an event code with a specific value:

if ev.matches(libevdev.EV_REL):
        pass

if ev.matches(libevdev.EV_REL.REL_X):
        pass

if ev.matches(libevdev.EV_REL.REL_X, 1):
        pass
type
Returns:the event type for this event
Return type:EventType

Module contents