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kivy_venv/lib/python3.11/site-packages/kivy/effects/__init__.py

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+'''
+Effects
+=======
+
+.. versionadded:: 1.7.0
+
+Everything starts with the :class:`~kinetic.KineticEffect`, the base class for
+computing velocity out of a movement.
+
+This base class is used to implement the :class:`~scroll.ScrollEffect`, a base
+class used for our :class:`~kivy.uix.scrollview.ScrollView` widget effect.
+We have multiple implementations:
+
+- :class:`~kivy.effects.scroll.ScrollEffect`: base class used for implementing
+  an effect. It only calculates the scrolling and the overscroll.
+- :class:`~kivy.effects.dampedscroll.DampedScrollEffect`: uses the overscroll
+  information to allow the user to drag more than expected. Once the user stops
+  the drag, the position is returned to one of the bounds.
+- :class:`~kivy.effects.opacityscroll.OpacityScrollEffect`: uses the overscroll
+  information to reduce the opacity of the scrollview widget. When the user
+  stops the drag, the opacity is set back to 1.
+
+'''

kivy_venv/lib/python3.11/site-packages/kivy/effects/dampedscroll.py

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+'''
+Damped scroll effect
+====================
+
+.. versionadded:: 1.7.0
+
+This damped scroll effect will use the
+:attr:`~kivy.effects.scroll.ScrollEffect.overscroll` to calculate the scroll
+value, and slows going back to the upper or lower limit.
+
+'''
+
+__all__ = ('DampedScrollEffect',)
+
+
+from kivy.effects.scroll import ScrollEffect
+from kivy.properties import NumericProperty, BooleanProperty
+from kivy.metrics import sp
+
+
+class DampedScrollEffect(ScrollEffect):
+    '''DampedScrollEffect class. See the module documentation for more
+    information.
+    '''
+
+    edge_damping = NumericProperty(0.25)
+    '''Edge damping.
+
+    :attr:`edge_damping` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.25
+    '''
+
+    spring_constant = NumericProperty(2.0)
+    '''Spring constant.
+
+    :attr:`spring_constant` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 2.0
+    '''
+
+    min_overscroll = NumericProperty(.5)
+    '''An overscroll less than this amount will be normalized to 0.
+
+    .. versionadded:: 1.8.0
+
+    :attr:`min_overscroll` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to .5.
+    '''
+
+    round_value = BooleanProperty(True)
+    '''If True, when the motion stops, :attr:`value` is rounded to the nearest
+    integer.
+
+    .. versionadded:: 1.8.0
+
+    :attr:`round_value` is a :class:`~kivy.properties.BooleanProperty` and
+    defaults to True.
+    '''
+
+    def update_velocity(self, dt):
+        if abs(self.velocity) <= self.min_velocity and self.overscroll == 0:
+            self.velocity = 0
+            # why does this need to be rounded? For now refactored it.
+            if self.round_value:
+                self.value = round(self.value)
+            return
+
+        total_force = self.velocity * self.friction * dt / self.std_dt
+        if abs(self.overscroll) > self.min_overscroll:
+            total_force += self.velocity * self.edge_damping
+            total_force += self.overscroll * self.spring_constant
+        else:
+            self.overscroll = 0
+
+        stop_overscroll = ''
+        if not self.is_manual:
+            if self.overscroll > 0 and self.velocity < 0:
+                stop_overscroll = 'max'
+            elif self.overscroll < 0 and self.velocity > 0:
+                stop_overscroll = 'min'
+
+        self.velocity = self.velocity - total_force
+        if not self.is_manual:
+            self.apply_distance(self.velocity * dt)
+            if stop_overscroll == 'min' and self.value > self.min:
+                self.value = self.min
+                self.velocity = 0
+                return
+            if stop_overscroll == 'max' and self.value < self.max:
+                self.value = self.max
+                self.velocity = 0
+                return
+        self.trigger_velocity_update()
+
+    def on_value(self, *args):
+        scroll_min = self.min
+        scroll_max = self.max
+        if scroll_min > scroll_max:
+            scroll_min, scroll_max = scroll_max, scroll_min
+        if self.value < scroll_min:
+            self.overscroll = self.value - scroll_min
+        elif self.value > scroll_max:
+            self.overscroll = self.value - scroll_max
+        else:
+            self.overscroll = 0
+        self.scroll = self.value
+
+    def on_overscroll(self, *args):
+        self.trigger_velocity_update()
+
+    def apply_distance(self, distance):
+        os = abs(self.overscroll)
+        if os:
+            distance /= 1. + os / sp(200.)
+        super(DampedScrollEffect, self).apply_distance(distance)

kivy_venv/lib/python3.11/site-packages/kivy/effects/kinetic.py

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+'''
+Kinetic effect
+==============
+
+.. versionadded:: 1.7.0
+
+The :class:`KineticEffect` is the base class that is used to compute the
+velocity out of a movement. When the movement is finished, the effect will
+compute the position of the movement according to the velocity, and reduce the
+velocity with a friction. The movement stop until the velocity is 0.
+
+Conceptually, the usage could be::
+
+    >>> effect = KineticEffect()
+    >>> effect.start(10)
+    >>> effect.update(15)
+    >>> effect.update(30)
+    >>> effect.stop(48)
+
+Over the time, you will start a movement of a value, update it, and stop the
+movement. At this time, you'll get the movement value into
+:attr:`KineticEffect.value`. On the example i've typed manually, the computed
+velocity will be::
+
+    >>> effect.velocity
+    3.1619100231163046
+
+After multiple clock interaction, the velocity will decrease according to
+:attr:`KineticEffect.friction`. The computed value will be stored in
+:attr:`KineticEffect.value`. The output of this `value` could be::
+
+    46.30038145219605
+    54.58302451968686
+    61.9229016256196
+    # ...
+
+'''
+
+__all__ = ('KineticEffect', )
+
+
+from time import time
+from kivy.event import EventDispatcher
+from kivy.properties import NumericProperty, BooleanProperty
+from kivy.clock import Clock
+
+
+class KineticEffect(EventDispatcher):
+    '''Kinetic effect class. See module documentation for more information.
+    '''
+
+    velocity = NumericProperty(0)
+    '''Velocity of the movement.
+
+    :attr:`velocity` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.
+    '''
+
+    friction = NumericProperty(0.05)
+    '''Friction to apply on the velocity
+
+    :attr:`friction` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.05.
+    '''
+
+    value = NumericProperty(0)
+    '''Value (during the movement and computed) of the effect.
+
+    :attr:`value` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.
+    '''
+
+    is_manual = BooleanProperty(False)
+    '''Indicate if a movement is in progress (True) or not (False).
+
+    :attr:`is_manual` is a :class:`~kivy.properties.BooleanProperty` and
+    defaults to False.
+    '''
+
+    max_history = NumericProperty(5)
+    '''Save up to `max_history` movement value into the history. This is used
+    for correctly calculating the velocity according to the movement.
+
+    :attr:`max_history` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 5.
+    '''
+
+    min_distance = NumericProperty(.1)
+    '''The minimal distance for a movement to have nonzero velocity.
+
+    .. versionadded:: 1.8.0
+
+    :attr:`min_distance` is :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.1.
+    '''
+
+    min_velocity = NumericProperty(.5)
+    '''Velocity below this quantity is normalized to 0. In other words,
+    any motion whose velocity falls below this number is stopped.
+
+    .. versionadded:: 1.8.0
+
+    :attr:`min_velocity` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.5.
+    '''
+
+    std_dt = NumericProperty(0.017)
+    ''' std_dt
+        correction update_velocity if dt is not constant
+
+    .. versionadded:: 2.0.0
+
+    :attr:`std_dt` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.017.
+    '''
+
+    def __init__(self, **kwargs):
+        self.history = []
+        self.trigger_velocity_update = Clock.create_trigger(
+            self.update_velocity, 0)
+        super(KineticEffect, self).__init__(**kwargs)
+
+    def apply_distance(self, distance):
+        if abs(distance) < self.min_distance:
+            self.velocity = 0
+        self.value += distance
+
+    def start(self, val, t=None):
+        '''Start the movement.
+
+        :Parameters:
+            `val`: float or int
+                Value of the movement
+            `t`: float, defaults to None
+                Time when the movement happen. If no time is set, it will use
+                time.time()
+        '''
+        self.is_manual = True
+        t = t or time()
+        self.velocity = 0
+        self.history = [(t, val)]
+
+    def update(self, val, t=None):
+        '''Update the movement.
+
+        See :meth:`start` for the arguments.
+        '''
+        t = t or time()
+        distance = val - self.history[-1][1]
+        self.apply_distance(distance)
+        self.history.append((t, val))
+        if len(self.history) > self.max_history:
+            self.history.pop(0)
+
+    def stop(self, val, t=None):
+        '''Stop the movement.
+
+        See :meth:`start` for the arguments.
+        '''
+        self.is_manual = False
+        t = t or time()
+        distance = val - self.history[-1][1]
+        self.apply_distance(distance)
+        newest_sample = (t, val)
+        old_sample = self.history[0]
+        for sample in self.history:
+            if (newest_sample[0] - sample[0]) < 10. / 60.:
+                break
+            old_sample = sample
+        distance = newest_sample[1] - old_sample[1]
+        duration = abs(newest_sample[0] - old_sample[0])
+        self.velocity = (distance / max(duration, 0.0001))
+        self.trigger_velocity_update()
+
+    def cancel(self):
+        '''Cancel a movement. This can be used in case :meth:`stop` cannot be
+        called. It will reset :attr:`is_manual` to False, and compute the
+        movement if the velocity is > 0.
+        '''
+        self.is_manual = False
+        self.trigger_velocity_update()
+
+    def update_velocity(self, dt):
+        '''(internal) Update the velocity according to the frametime and
+        friction.
+        '''
+        if abs(self.velocity) <= self.min_velocity:
+            self.velocity = 0
+            return
+
+        self.velocity -= self.velocity * self.friction * dt / self.std_dt
+        self.apply_distance(self.velocity * dt)
+        self.trigger_velocity_update()

kivy_venv/lib/python3.11/site-packages/kivy/effects/opacityscroll.py

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+'''
+Opacity scroll effect
+=====================
+
+Based on the :class:`~kivy.effects.damped.DampedScrollEffect`, this one will
+also decrease the opacity of the target widget during the overscroll.
+
+'''
+
+__all__ = ('OpacityScrollEffect', )
+
+
+from kivy.effects.dampedscroll import DampedScrollEffect
+
+
+class OpacityScrollEffect(DampedScrollEffect):
+    '''OpacityScrollEffect class. Uses the overscroll
+    information to reduce the opacity of the scrollview widget. When the user
+    stops the drag, the opacity is set back to 1.
+    '''
+
+    def on_overscroll(self, *args):
+        if self.target_widget and self.target_widget.height != 0:
+            alpha = (1.0 -
+                     abs(self.overscroll / float(self.target_widget.height)))
+            self.target_widget.opacity = min(1, alpha)
+        self.trigger_velocity_update()

kivy_venv/lib/python3.11/site-packages/kivy/effects/scroll.py

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+'''
+Scroll effect
+=============
+
+.. versionadded:: 1.7.0
+
+Based on the :class:`~kivy.effects.kinetic` effect, the :class:`ScrollEffect`
+will limit the movement to bounds determined by its :attr:`~ScrollEffect.min`
+and :attr:`~ScrollEffect.max` properties. If the movement exceeds these
+bounds, it will calculate the amount of :attr:`~ScrollEffect.overscroll` and
+try to return to the value of one of the bounds.
+
+This is very useful for implementing a scrolling list. We actually use this
+class as a base effect for our :class:`~kivy.uix.scrollview.ScrollView` widget.
+
+'''
+
+
+__all__ = ('ScrollEffect', )
+
+
+from time import time
+from kivy.effects.kinetic import KineticEffect
+from kivy.uix.widget import Widget
+from kivy.properties import NumericProperty, ObjectProperty
+
+
+class ScrollEffect(KineticEffect):
+    '''ScrollEffect class. See the module documentation for more information.
+    '''
+
+    drag_threshold = NumericProperty('20sp')
+    '''Minimum distance to travel before the movement is considered as a drag.
+
+    :attr:`drag_threshold` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 20sp.
+    '''
+
+    min = NumericProperty(0)
+    '''Minimum boundary to use for scrolling.
+
+    :attr:`min` is a :class:`~kivy.properties.NumericProperty` and defaults to
+    0.
+    '''
+
+    max = NumericProperty(0)
+    '''Maximum boundary to use for scrolling.
+
+    :attr:`max` is a :class:`~kivy.properties.NumericProperty` and defaults to
+    0.
+    '''
+
+    scroll = NumericProperty(0)
+    '''Computed value for scrolling. This value is different from
+    :py:attr:`kivy.effects.kinetic.KineticEffect.value`
+    in that it will return to one of the min/max bounds.
+
+    :attr:`scroll` is a :class:`~kivy.properties.NumericProperty` and defaults
+    to 0.
+    '''
+
+    overscroll = NumericProperty(0)
+    '''Computed value when the user over-scrolls i.e. goes out of the bounds.
+
+    :attr:`overscroll` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.
+    '''
+
+    target_widget = ObjectProperty(None, allownone=True, baseclass=Widget)
+    '''Widget to attach to this effect. Even if this class doesn't make changes
+    to the `target_widget` by default, subclasses can use it to change the
+    graphics or apply custom transformations.
+
+    :attr:`target_widget` is a :class:`~kivy.properties.ObjectProperty` and
+    defaults to None.
+    '''
+
+    displacement = NumericProperty(0)
+    '''Cumulative distance of the movement during the interaction. This is used
+    to determine if the movement is a drag (more than :attr:`drag_threshold`)
+    or not.
+
+    :attr:`displacement` is a :class:`~kivy.properties.NumericProperty` and
+    defaults to 0.
+    '''
+
+    def reset(self, pos):
+        '''(internal) Reset the value and the velocity to the `pos`.
+        Mostly used when the bounds are checked.
+        '''
+        self.value = pos
+        self.velocity = 0
+        if self.history:
+            val = self.history[-1][1]
+            self.history = [(time(), val)]
+
+    def on_value(self, *args):
+        scroll_min = self.min
+        scroll_max = self.max
+        if scroll_min > scroll_max:
+            scroll_min, scroll_max = scroll_max, scroll_min
+        if self.value < scroll_min:
+            self.overscroll = self.value - scroll_min
+            self.reset(scroll_min)
+        elif self.value > scroll_max:
+            self.overscroll = self.value - scroll_max
+            self.reset(scroll_max)
+        else:
+            self.scroll = self.value
+
+    def start(self, val, t=None):
+        self.is_manual = True
+        self.displacement = 0
+        return super(ScrollEffect, self).start(val, t)
+
+    def update(self, val, t=None):
+        self.displacement += abs(val - self.history[-1][1])
+        return super(ScrollEffect, self).update(val, t)
+
+    def stop(self, val, t=None):
+        self.is_manual = False
+        self.displacement += abs(val - self.history[-1][1])
+        if self.displacement <= self.drag_threshold:
+            self.velocity = 0
+            return
+        return super(ScrollEffect, self).stop(val, t)