Source code for kivy.input.motionevent

.. _motionevent:

Motion Event

The :class:`MotionEvent` is the base class used for events provided by
pointing devices (touch and non-touch). This class defines all the properties
and methods needed to handle 2D and 3D movements but has many more

Usually you would never need to create the :class:`MotionEvent` yourself as
this is the role of the :mod:`~kivy.input.providers`.

Flow of the motion events

1. The :class:`MotionEvent` 's are gathered from input providers by
2. Post processing is performed by registered processors
3. :class:`~kivy.base.EventLoopBase` dispatches all motion events using
   `on_motion` event to all registered listeners including the
4. Once received in :meth:`~kivy.core.window.WindowBase.on_motion` events
   (touch or non-touch) are all registered managers. If a touch event is not
   handled by at least one manager, then it is dispatched through
   :meth:`~kivy.core.window.WindowBase.on_touch_move` and
5. Widgets receive events in :meth:`~kivy.uix.widget.Widget.on_motion` method
   (if passed by a manager) or on `on_touch_xxx` methods.

Motion events and event managers

A motion event is a touch event if its :attr:`MotionEvent.is_touch` is set to
`True`. Beside `is_touch` attribute, :attr:`MotionEvent.type_id` can be used to
check for event's general type. Currently two types are dispatched by
input providers: "touch" and "hover".

Event managers can be used to dispatch any motion event throughout the widget
tree and a manager uses `type_id` to specify which event types it want to
receive. See :mod:`~kivy.eventmanager` to learn how to define and register
an event manager.

A manager can also assign a new `type_id` to
:attr:`MotionEvent.type_id` before dispatching it to the widgets. This useful
when dispatching a specific event::

    class MouseTouchManager(EventManagerBase):

        type_ids = ('touch',)

        def dispatch(self, etype, me):
            accepted = False
            if me.device == 'mouse':
                me.push() # Save current type_id and other values
                me.type_id = 'mouse_touch'
                # Dispatch mouse touch event to widgets which registered
                # to receive 'mouse_touch'
                for widget in self.window.children[:]:
                    if widget.dispatch('on_motion', etype, me):
                        accepted = True
                me.pop() # Restore
            return accepted

Listening to a motion event

If you want to receive all motion events, touch or not, you can bind the
MotionEvent from the :class:`~kivy.core.window.Window` to your own callback::

    def on_motion(self, etype, me):
        # will receive all motion events.


You can also listen to changes of the mouse position by watching


The :class:`MotionEvent` stores device specific information in various
properties listed in the :attr:`~MotionEvent.profile`.
For example, you can receive a MotionEvent that has an angle, a fiducial
ID, or even a shape. You can check the :attr:`~MotionEvent.profile`
attribute to see what is currently supported by the MotionEvent provider.

This is a short list of the profile values supported by default. Please check
the :attr:`MotionEvent.profile` property to see what profile values are

============== ================================================================
Profile value   Description
-------------- ----------------------------------------------------------------
angle          2D angle. Accessed via the `a` property.
button         Mouse button ('left', 'right', 'middle', 'scrollup' or
               'scrolldown'). Accessed via the `button` property.
markerid       Marker or Fiducial ID. Accessed via the `fid` property.
pos            2D position. Accessed via the `x`, `y` or `pos` properties.
pos3d          3D position. Accessed via the `x`, `y` or `z` properties.
pressure       Pressure of the contact. Accessed via the `pressure` property.
shape          Contact shape. Accessed via the `shape` property .
============== ================================================================

If you want to know whether the current :class:`MotionEvent` has an angle::

    def on_touch_move(self, touch):
        if 'angle' in touch.profile:
            print('The touch angle is', touch.a)

If you want to select only the fiducials::

    def on_touch_move(self, touch):
        if 'markerid' not in touch.profile:


__all__ = ('MotionEvent', )

import weakref
from inspect import isroutine
from copy import copy
from time import time

from kivy.eventmanager import MODE_DEFAULT_DISPATCH
from kivy.vector import Vector

class EnhancedDictionary(dict):

    def __getattr__(self, attr):
            return self.__getitem__(attr)
        except KeyError:
            return super(EnhancedDictionary, self).__getattr__(attr)

    def __setattr__(self, attr, value):
        self.__setitem__(attr, value)

class MotionEventMetaclass(type):

    def __new__(mcs, name, bases, attrs):
        __attrs__ = []
        for base in bases:
            if hasattr(base, '__attrs__'):
        if '__attrs__' in attrs:
        attrs['__attrs__'] = tuple(__attrs__)
        return super(MotionEventMetaclass, mcs).__new__(mcs, name,
                                                        bases, attrs)

MotionEventBase = MotionEventMetaclass('MotionEvent', (object, ), {})

[docs]class MotionEvent(MotionEventBase): '''Abstract class that represents an input event. :Parameters: `id`: str unique ID of the MotionEvent `args`: list list of parameters, passed to the depack() function ''' __uniq_id = 0 __attrs__ = \ ('device', 'push_attrs', 'push_attrs_stack', 'is_touch', 'type_id', 'id', 'dispatch_mode', 'shape', 'profile', # current position, in 0-1 range 'sx', 'sy', 'sz', # first position set, in 0-1 range 'osx', 'osy', 'osz', # last position set, in 0-1 range 'psx', 'psy', 'psz', # delta from the last position and current one, in 0-1 range 'dsx', 'dsy', 'dsz', # current position, in screen range 'x', 'y', 'z', # first position set, in screen range 'ox', 'oy', 'oz', # last position set, in 0-1 range 'px', 'py', 'pz', # delta from the last position and current one, in screen range 'dx', 'dy', 'dz', 'time_start', 'is_double_tap', 'double_tap_time', 'is_triple_tap', 'triple_tap_time', 'ud') def __init__(self, device, id, args, is_touch=False, type_id=None): if self.__class__ == MotionEvent: raise NotImplementedError('class MotionEvent is abstract') MotionEvent.__uniq_id += 1 #: True if the MotionEvent is a touch. self.is_touch = is_touch #: (Experimental) String to identify event type. #: #: .. versionadded:: 2.1.0 self.type_id = type_id #: (Experimental) Used by a event manager or a widget to assign #: the dispatching mode. Defaults to #: :const:`~kivy.eventmanager.MODE_DEFAULT_DISPATCH`. See #: :mod:`~kivy.eventmanager` for available modes. #: #: .. versionadded:: 2.1.0 self.dispatch_mode = MODE_DEFAULT_DISPATCH #: Attributes to push by default, when we use :meth:`push` : x, y, z, #: dx, dy, dz, ox, oy, oz, px, py, pz. self.push_attrs_stack = [] self.push_attrs = ('x', 'y', 'z', 'dx', 'dy', 'dz', 'ox', 'oy', 'oz', 'px', 'py', 'pz', 'pos', 'type_id', 'dispatch_mode') #: Uniq ID of the event. You can safely use this property, it will be #: never the same across all existing events. self.uid = MotionEvent.__uniq_id #: Device used for creating this event. self.device = device # For grab self.grab_list = [] self.grab_exclusive_class = None self.grab_state = False #: Used to determine which widget the event is being dispatched to. #: Check the :meth:`grab` function for more information. self.grab_current = None #: Currently pressed button. self.button = None #: Profiles currently used in the event. self.profile = [] #: Id of the event, not unique. This is generally the Id set by the #: input provider, like ID in TUIO. If you have multiple TUIO sources, #: then same id can be used. Prefer to use :attr:`uid` attribute #: instead. = id #: Shape of the touch event, subclass of #: :class:`~kivy.input.shape.Shape`. #: By default, the property is set to None. self.shape = None #: X position, in 0-1 range. = 0.0 #: Y position, in 0-1 range. = 0.0 #: Z position, in 0-1 range. = 0.0 #: Origin X position, in 0-1 range. self.osx = None #: Origin Y position, in 0-1 range. self.osy = None #: Origin Z position, in 0-1 range. self.osz = None #: Previous X position, in 0-1 range. self.psx = None #: Previous Y position, in 0-1 range. self.psy = None #: Previous Z position, in 0-1 range. self.psz = None #: Delta between and self.psx, in 0-1 range. self.dsx = None #: Delta between and self.psy, in 0-1 range. self.dsy = None #: Delta between and self.psz, in 0-1 range. self.dsz = None #: X position, in window range. self.x = 0.0 #: Y position, in window range. self.y = 0.0 #: Z position, in window range. self.z = 0.0 #: Origin X position, in window range. self.ox = None #: Origin Y position, in window range. self.oy = None #: Origin Z position, in window range. self.oz = None #: Previous X position, in window range. self.px = None #: Previous Y position, in window range. = None #: Previous Z position, in window range. self.pz = None #: Delta between self.x and self.px, in window range. self.dx = None #: Delta between self.y and, in window range. self.dy = None #: Delta between self.z and self.pz, in window range. = None #: Position (X, Y), in window range. self.pos = (0.0, 0.0) #: Initial time of the event creation. self.time_start = time() #: Time of the last update. self.time_update = self.time_start #: Time of the end event (last event usage). self.time_end = -1 #: Indicate if the touch event is a double tap or not. self.is_double_tap = False #: Indicate if the touch event is a triple tap or not. #: #: .. versionadded:: 1.7.0 self.is_triple_tap = False #: If the touch is a :attr:`is_double_tap`, this is the time #: between the previous tap and the current touch. self.double_tap_time = 0 #: If the touch is a :attr:`is_triple_tap`, this is the time #: between the first tap and the current touch. #: #: .. versionadded:: 1.7.0 self.triple_tap_time = 0 #: User data dictionary. Use this dictionary to save your own data on #: the event. self.ud = EnhancedDictionary() #: If set to `True` (default) keeps first previous position #: (X, Y, Z in 0-1 range) and ignore all other until #: :meth:`MotionEvent.dispatch_done` is called from the `EventLoop`. #: #: This attribute is needed because event provider can make many calls #: to :meth:`MotionEvent.move`, but for all those calls event is #: dispatched to the listeners only once. Assigning `False` will keep #: latest previous position. See :meth:`MotionEvent.move`. #: #: .. versionadded:: 2.1.0 self.sync_with_dispatch = True #: Keep first previous position if :attr:`sync_with_dispatch` is #: `True`. self._keep_prev_pos = True #: Flag that first dispatch of this event is done. self._first_dispatch_done = False self.depack(args)
[docs] def depack(self, args): '''Depack `args` into attributes of the class''' if self.osx is None \ or self.sync_with_dispatch and not self._first_dispatch_done: # Sync origin/previous/current positions until the first # dispatch (etype == 'begin') is done. self.osx = self.psx = self.osy = self.psy = self.osz = self.psz = # update the delta self.dsx = - self.psx self.dsy = - self.psy self.dsz = - self.psz
[docs] def grab(self, class_instance, exclusive=False): '''Grab this motion event. If this event is a touch you can grab it if you want to receive subsequent :meth:`~kivy.uix.widget.Widget.on_touch_move` and :meth:`~kivy.uix.widget.Widget.on_touch_up` events, even if the touch is not dispatched by the parent: .. code-block:: python def on_touch_down(self, touch): touch.grab(self) def on_touch_move(self, touch): if touch.grab_current is self: # I received my grabbed touch else: # it's a normal touch def on_touch_up(self, touch): if touch.grab_current is self: # I receive my grabbed touch, I must ungrab it! touch.ungrab(self) else: # it's a normal touch pass .. versionchanged:: 2.1.0 Allowed grab for non-touch events. ''' if self.grab_exclusive_class is not None: raise Exception('Event is exclusive and cannot be grabbed') class_instance = weakref.ref(class_instance.__self__) if exclusive: self.grab_exclusive_class = class_instance self.grab_list.append(class_instance)
[docs] def ungrab(self, class_instance): '''Ungrab a previously grabbed motion event. ''' class_instance = weakref.ref(class_instance.__self__) if self.grab_exclusive_class == class_instance: self.grab_exclusive_class = None if class_instance in self.grab_list: self.grab_list.remove(class_instance)
[docs] def dispatch_done(self): '''Notify that dispatch to the listeners is done. Called by the :meth:`EventLoopBase.post_dispatch_input`. .. versionadded:: 2.1.0 ''' self._keep_prev_pos = True self._first_dispatch_done = True
[docs] def move(self, args): '''Move to another position. ''' if self.sync_with_dispatch: if self._keep_prev_pos: self.psx, self.psy, self.psz =,, self._keep_prev_pos = False else: self.psx, self.psy, self.psz =,, self.time_update = time() self.depack(args)
[docs] def scale_for_screen(self, w, h, p=None, rotation=0, smode='None', kheight=0): '''Scale position for the screen. .. versionchanged:: 2.1.0 Max value for `x`, `y` and `z` is changed respectively to `w` - 1, `h` - 1 and `p` - 1. ''' x_max, y_max = max(0, w - 1), max(0, h - 1) absolute = self.to_absolute_pos self.x, self.y = absolute(,, x_max, y_max, rotation) self.ox, self.oy = absolute(self.osx, self.osy, x_max, y_max, rotation) self.px, = absolute(self.psx, self.psy, x_max, y_max, rotation) z_max = 0 if p is None else max(0, p - 1) self.z = * z_max self.oz = self.osz * z_max self.pz = self.psz * z_max if smode: # Adjust y for keyboard height if smode == 'pan' or smode == 'below_target': self.y -= kheight self.oy -= kheight -= kheight elif smode == 'scale': offset = kheight * (self.y - h) / (h - kheight) self.y += offset self.oy += offset += offset # Update delta values self.dx = self.x - self.px self.dy = self.y - = self.z - self.pz # Cache position self.pos = self.x, self.y
[docs] def to_absolute_pos(self, nx, ny, x_max, y_max, rotation): '''Transforms normalized (0-1) coordinates `nx` and `ny` to absolute coordinates using `x_max`, `y_max` and `rotation`. :raises: `ValueError`: If `rotation` is not one of: 0, 90, 180 or 270 .. versionadded:: 2.1.0 ''' if rotation == 0: return nx * x_max, ny * y_max elif rotation == 90: return ny * y_max, (1 - nx) * x_max elif rotation == 180: return (1 - nx) * x_max, (1 - ny) * y_max elif rotation == 270: return (1 - ny) * y_max, nx * x_max raise ValueError('Invalid rotation %s, ' 'valid values are 0, 90, 180 or 270' % rotation)
[docs] def push(self, attrs=None): '''Push attribute values in `attrs` onto the stack. ''' if attrs is None: attrs = self.push_attrs values = [getattr(self, x) for x in attrs] self.push_attrs_stack.append((attrs, values))
[docs] def pop(self): '''Pop attributes values from the stack. ''' attrs, values = self.push_attrs_stack.pop() for i in range(len(attrs)): setattr(self, attrs[i], values[i])
[docs] def apply_transform_2d(self, transform): '''Apply a transformation on x, y, z, px, py, pz, ox, oy, oz, dx, dy, dz. ''' self.x, self.y = self.pos = transform(self.x, self.y) self.px, = transform(self.px, self.ox, self.oy = transform(self.ox, self.oy) self.dx = self.x - self.px self.dy = self.y -
[docs] def copy_to(self, to): '''Copy some attribute to another motion event object.''' for attr in self.__attrs__: to.__setattr__(attr, copy(self.__getattribute__(attr)))
[docs] def distance(self, other_touch): '''Return the distance between the two events. ''' return Vector(self.pos).distance(other_touch.pos)
def update_time_end(self): self.time_end = time() # facilities @property def dpos(self): '''Return delta between last position and current position, in the screen coordinate system (self.dx, self.dy).''' return self.dx, self.dy @property def opos(self): '''Return the initial position of the motion event in the screen coordinate system (self.ox, self.oy).''' return self.ox, self.oy @property def ppos(self): '''Return the previous position of the motion event in the screen coordinate system (self.px,''' return self.px, @property def spos(self): '''Return the position in the 0-1 coordinate system (, ''' return, def __str__(self): basename = str(self.__class__) classname = basename.split('.')[-1].replace('>', '').replace('\'', '') return '<%s spos=%s pos=%s>' % (classname, self.spos, self.pos) def __repr__(self): out = [] for x in dir(self): v = getattr(self, x) if x[0] == '_': continue if isroutine(v): continue out.append('%s="%s"' % (x, v)) return '<%s %s>' % ( self.__class__.__name__, ' '.join(out)) @property def is_mouse_scrolling(self, *args): '''Returns True if the touch event is a mousewheel scrolling .. versionadded:: 1.6.0 ''' return 'button' in self.profile and 'scroll' in self.button