'''
Switch
======

.. versionadded:: 1.0.7

.. image:: images/switch-on.jpg
    :align: right

.. image:: images/switch-off.jpg
    :align: right

The :class:`Switch` widget is active or inactive, like a mechanical light
switch. The user can swipe to the left/right to activate/deactivate it::

    switch = Switch(active=True)

To attach a callback that listens to the activation state::

    def callback(instance, value):
        print('the switch', instance, 'is', value)

    switch = Switch()
    switch.bind(active=callback)

By default, the representation of the widget is static. The minimum size
required is 83x32 pixels (defined by the background image). The image is
centered within the widget.

The entire widget is active, not just the part with graphics. As long as you
swipe over the widget's bounding box, it will work.

.. note::

    If you want to control the state with a single touch instead of a swipe,
    use the :class:`ToggleButton` instead.

Kv Example::

    BoxLayout:
        Label:
            text: 'power up'
        Switch:
            id: switch
        Label:
            text: 'woooooooooooh' if switch.active else ''
'''


from kivy.uix.widget import Widget
from kivy.animation import Animation
from kivy.properties import BooleanProperty, ObjectProperty, NumericProperty


class Switch(Widget):
    '''Switch class. See module documentation for more information.
    '''
    active = BooleanProperty(False)
    '''Indicate whether the switch is active or inactive.

    :attr:`active` is a :class:`~kivy.properties.BooleanProperty` and defaults
    to False.
    '''

    touch_control = ObjectProperty(None, allownone=True)
    '''(internal) Contains the touch that currently interacts with the switch.

    :attr:`touch_control` is an :class:`~kivy.properties.ObjectProperty`
    and defaults to None.
    '''

    touch_distance = NumericProperty(0)
    '''(internal) Contains the distance between the initial position of the
    touch and the current position to determine if the swipe is from the left
    or right.

    :attr:`touch_distance` is a :class:`~kivy.properties.NumericProperty`
    and defaults to 0.
    '''

    active_norm_pos = NumericProperty(0)
    '''(internal) Contains the normalized position of the movable element
    inside the switch, in the 0-1 range.

    :attr:`active_norm_pos` is a :class:`~kivy.properties.NumericProperty`
    and defaults to 0.
    '''

    def on_touch_down(self, touch):
        if self.disabled or self.touch_control is not None:
            return
        if not self.collide_point(*touch.pos):
            return
        touch.grab(self)
        self.touch_distance = 0
        self.touch_control = touch
        return True

    def on_touch_move(self, touch):
        if touch.grab_current is not self:
            return
        self.touch_distance = touch.x - touch.ox
        return True

    def on_touch_up(self, touch):
        if touch.grab_current is not self:
            return
        touch.ungrab(self)
        # depending of the distance, activate by norm pos or invert
        if abs(touch.ox - touch.x) < 5:
            self.active = not self.active
        else:
            self.active = self.active_norm_pos > 0.5
        Animation(active_norm_pos=int(self.active), t='out_quad',
                  d=.2).start(self)
        self.touch_control = None
        return True


if __name__ == '__main__':
    from kivy.base import runTouchApp
    runTouchApp(Switch())