# Handling the keyboard

The package `pynput.keyboard` contains classes for controlling and monitoring the keyboard.

## Controlling the keyboard

Use `pynput.keyboard.Controller` like this:

    from pynput.keyboard import Key, Controller

    keyboard = Controller()

    # Press and release space
    keyboard.press(Key.space)
    keyboard.release(Key.space)

    # Type a lower case A; this will work even if no key on the
    # physical keyboard is labelled 'A'
    keyboard.press('a')
    keyboard.release('a')

    # Type two upper case As
    keyboard.press('A')
    keyboard.release('A')
    with keyboard.pressed(Key.shift):
        keyboard.press('a')
        keyboard.release('a')

    # Type 'Hello World' using the shortcut type method
    keyboard.type('Hello World')

## Monitoring the keyboard

Use `pynput.keyboard.Listener` like this:

    from pynput import keyboard

    def on_press(key):
        try:
            print('alphanumeric key {0} pressed'.format(
                key.char))
        except AttributeError:
            print('special key {0} pressed'.format(
                key))

    def on_release(key):
        print('{0} released'.format(
            key))
        if key == keyboard.Key.esc:
            # Stop listener
            return False

    # Collect events until released
    with keyboard.Listener(
            on_press=on_press,
            on_release=on_release) as listener:
        listener.join()

    # ...or, in a non-blocking fashion:
    listener = keyboard.Listener(
        on_press=on_press,
        on_release=on_release)
    listener.start()

A keyboard listener is a `threading.Thread`, and all callbacks will be invoked from the thread.

Call `pynput.keyboard.Listener.stop` from anywhere, raise `StopException` or return `False` from a callback to stop the listener.

The `key` parameter passed to callbacks is a `pynput.keyboard.Key`, for special keys, a `pynput.keyboard.KeyCode` for normal alphanumeric keys, or just `None` for unknown keys.

When using the non-blocking version above, the current thread will continue executing. This might be necessary when integrating with other GUI frameworks that incorporate a main-loop, but when run from a script, this will cause the program to terminate immediately.

### The keyboard listener thread

The listener callbacks are invoked directly from an operating thread on some platforms, notably Windows.

This means that long running procedures and blocking operations should not be invoked from the callback, as this risks freezing input for all processes.

A possible workaround is to just dispatch incoming messages to a queue, and let a separate thread handle them.

### Handling keyboard listener errors

If a callback handler raises an exception, the listener will be stopped. Since callbacks run in a dedicated thread, the exceptions will not automatically be reraised.

To be notified about callback errors, call `Thread.join` on the listener instance:

    from pynput import keyboard

    class MyException(Exception): pass

    def on_press(key):
        if key == keyboard.Key.esc:
            raise MyException(key)

    # Collect events until released
    with keyboard.Listener(
            on_press=on_press) as listener:
        try:
            listener.join()
        except MyException as e:
            print('{0} was pressed'.format(e.args[0]))

### Toggling event listening for the keyboard listener

Once `pynput.keyboard.Listener.stop` has been called, the listener cannot be restarted, since listeners are instances of `threading.Thread`.

If your application requires toggling listening events, you must either add an internal flag to ignore events when not required, or create a new listener when resuming listening.

### Synchronous event listening for the keyboard listener

To simplify scripting, synchronous event listening is supported through the utility class `pynput.keyboard.Events`. This class supports reading single events in a non-blocking fashion, as well as iterating over all events.

To read a single event, use the following code:

    from pynput import keyboard

    # The event listener will be running in this block
    with keyboard.Events() as events:
        # Block at most one second
        event = events.get(1.0)
        if event is None:
            print('You did not press a key within one second')
        else:
            print('Received event {}'.format(event))

To iterate over keyboard events, use the following code:

    from pynput import keyboard

    # The event listener will be running in this block
    with keyboard.Events() as events:
        for event in events:
            if event.key == keyboard.Key.esc:
                break
            else:
                print('Received event {}'.format(event))

Please note that the iterator method does not support non-blocking operation, so it will wait for at least one keyboard event.

The events will be instances of the inner classes found in `pynput.keyboard.Events`.

### Global hotkeys

A common use case for keyboard monitors is reacting to global hotkeys. Since a listener does not maintain any state, hotkeys involving multiple keys must store this state somewhere.

pynput provides the class `pynput.keyboard.HotKey` for this purpose. It contains two methods to update the state, designed to be easily interoperable with a keyboard listener: `pynput.keyboard.HotKey.press` and `pynput.keyboard.HotKey.release` which can be directly passed as listener callbacks.

The intended usage is as follows:

    from pynput import keyboard

    def on_activate():
        print('Global hotkey activated!')

    def for_canonical(f):
        return lambda k: f(l.canonical(k))

    hotkey = keyboard.HotKey(
        keyboard.HotKey.parse('<ctrl>+<alt>+h'),
        on_activate)
    with keyboard.Listener(
            on_press=for_canonical(hotkey.press),
            on_release=for_canonical(hotkey.release)) as l:
        l.join()

This will create a hotkey, and then use a listener to update its state. Once all the specified keys are pressed simultaneously, `on_activate` will be invoked.

Note that keys are passed through `pynput.keyboard.Listener.canonical` before being passed to the `HotKey` instance. This is to remove any modifier state from the key events, and to normalise modifiers with more than one physical button.

The method `pynput.keyboard.HotKey.parse` is a convenience function to transform shortcut strings to key collections. Please see its documentation for more information.

To register a number of global hotkeys, use the convenience class `pynput.keyboard.GlobalHotKeys`:

    from pynput import keyboard

    def on_activate_h():
        print('<ctrl>+<alt>+h pressed')

    def on_activate_i():
        print('<ctrl>+<alt>+i pressed')

    with keyboard.GlobalHotKeys({
            '<ctrl>+<alt>+h': on_activate_h,
            '<ctrl>+<alt>+i': on_activate_i}) as h:
        h.join()

## Reference

class pynput.keyboard.Controller

  A controller for sending virtual keyboard events to the system.

  exception InvalidCharacterException

    The exception raised when an invalid character is encountered in the string passed to `Controller.type()`.

    Its first argument is the index of the character in the string, and the second the character.

  exception InvalidKeyException

    The exception raised when an invalid `key` parameter is passed to either `Controller.press()` or `Controller.release()`.

    Its first argument is the `key` parameter.

  property alt_gr_pressed

    Whether altgr is pressed.

    Please note that this reflects only the internal state of this controller. See `modifiers` for more information.

  property alt_pressed

    Whether any alt key is pressed.

    Please note that this reflects only the internal state of this controller. See `modifiers` for more information.

  property ctrl_pressed

    Whether any ctrl key is pressed.

    Please note that this reflects only the internal state of this controller. See `modifiers` for more information.

  property modifiers

    The currently pressed modifier keys.

    Please note that this reflects only the internal state of this controller, and not the state of the operating system keyboard buffer. This property cannot be used to determine whether a key is physically pressed.

    Only the generic modifiers will be set; when pressing either `Key.shift_l`, `Key.shift_r` or `Key.shift`, only `Key.shift` will be present.

    Use this property within a context block thus:

        with controller.modifiers as modifiers:
            with_block()

    This ensures that the modifiers cannot be modified by another thread.

  press(key)

    Presses a key.

    A key may be either a string of length 1, one of the `Key` members or a `KeyCode`.

    Strings will be transformed to `KeyCode` using `KeyCode.char()`. Members of `Key` will be translated to their `value()`.

    Parameters

      key – The key to press.

    Raises

      - InvalidKeyException – if the key is invalid

      - ValueError – if `key` is a string, but its length is not `1`

  pressed(*args)

    Executes a block with some keys pressed.

    Parameters

      keys – The keys to keep pressed.

  release(key)

    Releases a key.

    A key may be either a string of length 1, one of the `Key` members or a `KeyCode`.

    Strings will be transformed to `KeyCode` using `KeyCode.char()`. Members of `Key` will be translated to their `value()`.

    Parameters

      key – The key to release. If this is a string, it is passed to `touches()` and the returned releases are used.

    Raises

      - InvalidKeyException – if the key is invalid

      - ValueError – if `key` is a string, but its length is not `1`

  property shift_pressed

    Whether any shift key is pressed, or caps lock is toggled.

    Please note that this reflects only the internal state of this controller. See `modifiers` for more information.

  tap(key)

    Presses and releases a key.

    This is equivalent to the following code:

        controller.press(key)
        controller.release(key)

    Parameters

      key – The key to press.

    Raises

      - InvalidKeyException – if the key is invalid

      - ValueError – if `key` is a string, but its length is not `1`

  touch(key, is_press)

    Calls either `press()` or `release()` depending on the value of `is_press`.

    Parameters

      - key – The key to press or release.

      - is_press (bool) – Whether to press the key.

    Raises

      InvalidKeyException – if the key is invalid

  type(string)

    Types a string.

    This method will send all key presses and releases necessary to type all characters in the string.

    Parameters

      string (str) – The string to type.

    Raises

      InvalidCharacterException – if an untypable character is encountered

class pynput.keyboard.Listener(on_press=None, on_release=None, suppress=False, **kwargs)

  A listener for keyboard events.

  Instances of this class can be used as context managers. This is equivalent to the following code:

      listener.start()
      try:
          listener.wait()
          with_statements()
      finally:
          listener.stop()

  This class inherits from `threading.Thread` and supports all its methods. It will set `daemon` to `True` when created.

  Parameters

    - on_press (callable) –

      The callback to call when a button is pressed.

      It will be called with the argument `(key)`, where `key` is a `KeyCode`, a `Key` or `None` if the key is unknown.

    - on_release (callable) –

      The callback to call when a button is released.

      It will be called with the argument `(key)`, where `key` is a `KeyCode`, a `Key` or `None` if the key is unknown.

    - suppress (bool) – Whether to suppress events. Setting this to `True` will prevent the input events from being passed to the rest of the system.

    - kwargs –

      Any non-standard platform dependent options. These should be prefixed with the platform name thus: `darwin_`, `xorg_` or `win32_`.

      Supported values are:

      `darwin_intercept`

        A callable taking the arguments `(event_type, event)`, where `event_type` is `Quartz.kCGEventKeyDown` or `Quartz.kCGEventKeyDown`, and `event` is a `CGEventRef`.

        This callable can freely modify the event using functions like `Quartz.CGEventSetIntegerValueField`. If this callable does not return the event, the event is suppressed system wide.

      `win32_event_filter`

        A callable taking the arguments `(msg, data)`, where `msg` is the current message, and `data` associated data as a KBDLLHOOKSTRUCT.

        If this callback returns `False`, the event will not be propagated to the listener callback.

        If `self.suppress_event()` is called, the event is suppressed system wide.

  __init__(on_press=None, on_release=None, suppress=False, **kwargs)

    This constructor should always be called with keyword arguments. Arguments are:

    group should be None; reserved for future extension when a ThreadGroup class is implemented.

    target is the callable object to be invoked by the run() method. Defaults to None, meaning nothing is called.

    name is the thread name. By default, a unique name is constructed of the form “Thread-N” where N is a small decimal number.

    args is the argument tuple for the target invocation. Defaults to ().

    kwargs is a dictionary of keyword arguments for the target invocation. Defaults to {}.

    If a subclass overrides the constructor, it must make sure to invoke the base class constructor (Thread.__init__()) before doing anything else to the thread.

  property running

    Whether the listener is currently running.

  start()

    Start the thread’s activity.

    It must be called at most once per thread object. It arranges for the object’s run() method to be invoked in a separate thread of control.

    This method will raise a RuntimeError if called more than once on the same thread object.

  stop()

    Stops listening for events.

    When this method returns, no more events will be delivered. Once this method has been called, the listener instance cannot be used any more, since a listener is a `threading.Thread`, and once stopped it cannot be restarted.

    To resume listening for event, a new listener must be created.

  wait()

    Waits for this listener to become ready.

class pynput.keyboard.Key(value)

  A class representing various buttons that may not correspond to letters. This includes modifier keys and function keys.

  The actual values for these items differ between platforms. Some platforms may have additional buttons, but these are guaranteed to be present everywhere.

  alt = 0

    A generic Alt key. This is a modifier.

  alt_gr = 0

    The AltGr key. This is a modifier.

  alt_l = 0

    The left Alt key. This is a modifier.

  alt_r = 0

    The right Alt key. This is a modifier.

  backspace = 0

    The Backspace key.

  caps_lock = 0

    The CapsLock key.

  cmd = 0

    A generic command button. On PC platforms, this corresponds to the Super key or Windows key, and on Mac it corresponds to the Command key. This may be a modifier.

  cmd_l = 0

    The left command button. On PC platforms, this corresponds to the Super key or Windows key, and on Mac it corresponds to the Command key. This may be a modifier.

  cmd_r = 0

    The right command button. On PC platforms, this corresponds to the Super key or Windows key, and on Mac it corresponds to the Command key. This may be a modifier.

  ctrl = 0

    A generic Ctrl key. This is a modifier.

  ctrl_l = 0

    The left Ctrl key. This is a modifier.

  ctrl_r = 0

    The right Ctrl key. This is a modifier.

  delete = 0

    The Delete key.

  down = 0

    A down arrow key.

  end = 0

    The End key.

  enter = 0

    The Enter or Return key.

  esc = 0

    The Esc key.

  f1 = 0

    The function keys. F1 to F20 are defined.

  home = 0

    The Home key.

  insert = 0

    The Insert key. This may be undefined for some platforms.

  left = 0

    A left arrow key.

  media_next = 0

    The next track button.

  media_play_pause = 0

    The play/pause toggle.

  media_previous = 0

    The previous track button.

  media_volume_down = 0

    The volume down button.

  media_volume_mute = 0

    The volume mute button.

  media_volume_up = 0

    The volume up button.

  menu = 0

    The Menu key. This may be undefined for some platforms.

  num_lock = 0

    The NumLock key. This may be undefined for some platforms.

  page_down = 0

    The PageDown key.

  page_up = 0

    The PageUp key.

  pause = 0

    The Pause/Break key. This may be undefined for some platforms.

  print_screen = 0

    The PrintScreen key. This may be undefined for some platforms.

  right = 0

    A right arrow key.

  scroll_lock = 0

    The ScrollLock key. This may be undefined for some platforms.

  shift = 0

    A generic Shift key. This is a modifier.

  shift_l = 0

    The left Shift key. This is a modifier.

  shift_r = 0

    The right Shift key. This is a modifier.

  space = 0

    The Space key.

  tab = 0

    The Tab key.

  up = 0

    An up arrow key.

class pynput.keyboard.KeyCode(vk=None, char=None, is_dead=False, **kwargs)

  A `KeyCode` represents the description of a key code used by the operating system.

  classmethod from_char(char, **kwargs)

    Creates a key from a character.

    Parameters

      char (str) – The character.

    Returns

      a key code

  classmethod from_dead(char, **kwargs)

    Creates a dead key.

    Parameters

      char – The dead key. This should be the unicode character representing the stand alone character, such as `'~'` for COMBINING TILDE.

    Returns

      a key code

  classmethod from_vk(vk, **kwargs)

    Creates a key from a virtual key code.

    Parameters

      - vk – The virtual key code.

      - kwargs – Any other parameters to pass.

    Returns

      a key code

  join(key)

    Applies this dead key to another key and returns the result.

    Joining a dead key with space (`' '`) or itself yields the non-dead version of this key, if one exists; for example, `KeyCode.from_dead('~').join(KeyCode.from_char(' '))` equals `KeyCode.from_char('~')` and `KeyCode.from_dead('~').join(KeyCode.from_dead('~'))`.

    Parameters

      key (KeyCode) – The key to join with this key.

    Returns

      a key code

    Raises

      ValueError – if the keys cannot be joined