kivy test UnderlineSelection Behavior (for KivyStudio)

canvas_before_rect.py

'''folder: root/bhv'''

from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.properties import ListProperty

KV = '''
<CanvasBeforeRect>
    canvas_color: [0.5,0.5,0.5,1.]
    canvas.before:
        Color:
            rgba: self.canvas_color
        Rectangle:
            pos:self.canvas_pos
            size: self.canvas_size
'''

class CanvasBeforeRect(Widget):

    canvas_pos = ListProperty([0,0])
    canvas_size = ListProperty([100,100])

    def __init__(self, **kwargs):

        super(CanvasBeforeRect, self).__init__(**kwargs)
        self.canvas_pos = self.pos
        self.canvas_size = self.size

Builder.load_string(KV)

color_property.py

'''folder: root/properties'''

from kivy.properties import AliasProperty

from kivy.utils import rgba

class ColorProperty(AliasProperty):
    '''gets kivy rgba or hex string (#2B2B32); returns kivy rgba'''
    _data = []

    def __init__(self, **kwargs):
        kwargs['getter'] = self._getter
        kwargs['setter'] = self._setter

        kwargs['cache'] =True
        super().__init__(**kwargs)

    def _getter(self, obj):

        return self._data

    def _setter(self, obj, value):

        if type(value) is str:
            value = rgba(value)

        self._data = value
        return True  # Value changed, dispatch event

main.py

'''folder: root'''

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.label import Label
from kivy.uix.widget import Widget

from bhv.underline_selection_bhv import UnderlineSelectionBhv

KV = """
BoxLayout
    MyLabel
    MyLabel
    MyLabel
    MyLabel

<MyLabel>
    text: '123'

    on_touch_down: if self.collide_point(*args[1].pos):\
        self.selected = True
"""


class MyLabel(
              UnderlineSelectionBhv,
              Label
              ):
    pass


class MyApp(App):
    def build(self):
        self.root = Builder.load_string(KV)


MyApp().run()

rgba_color_bhv.py

'''folder: root/bhv'''

'''instead I can use ColorProperty from kivy.properties'''

from properties.color_property import ColorProperty

class RgbaColorBhv(object):
    canvas_color = ColorProperty(value = [0.5,0.5,0.5,1.])

underline_selection_bhv.py

'''folder: root/bhv'''

from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.properties import BooleanProperty

from bhv.canvas_before_rect import CanvasBeforeRect
from bhv.rgba_color_bhv import RgbaColorBhv

KV = '''
<UnderlineSelectionBhv>
    selected_color: '#00BA82'
    unselected_color: '#404049'

    canvas_size: self.width, 2
    canvas_pos: self.pos

    canvas_color: self.selected_color if self.selected else self.unselected_color
'''

class UnderlineSelectionBhv(
                            RgbaColorBhv,
                            CanvasBeforeRect,
                            Widget
                            ):

    selected =  BooleanProperty(False)

Builder.load_string(KV)

Example (gif):
https://imgur.com/3RBrRin