score.py

from kivy.app                           import App
from kivy.animation                     import Animation
from kivy.uix.boxlayout                 import BoxLayout
from kivy.uix.button                    import Button
from kivy.uix.label                     import Label
from kivy.graphics.vertex_instructions  import Rectangle
from kivy.graphics.context_instructions import Color
from kivy.lang                          import Builder
from kivy.clock                         import ClockBase, Clock
from kivy.properties                    import ListProperty
from numpy import array

class ScoreApp(App):
    def build(self):
        return MyBoxLayout()

class MyBoxLayout(BoxLayout):

    def increase_score(self, *args):
        self.event = Clock.schedule_interval(self.clock_increase_score, .2)
        #self.event()

    def clock_increase_score(self, *args):

        self.ids.score_label.color_grad[0] -= .01 
        self.ids.score_label.color_grad[1] += .01
        self.ids.score_label.text = str(int(self.ids.score_label.text) + 1)

    def shut_increase_score(self, *args):
        self.event.cancel()

class ScoreLabel(Label):
    color_grad = ListProperty([1,0,0,1])

class MyButton(Button):

    def on_touch_down(self, touch):
        pass

Builder.load_string('''
<MyBoxLayout>:
    Button:
        text: '+'
        font_size: 100
        on_press: root.increase_score()
        on_release: root.shut_increase_score()
    ScoreLabel:
        id: score_label
        color_grad: 1,0,0,1
        text: '0'
        font_size: 100
        canvas.before:
            Color:
                rgba: self.color_grad
            Rectangle:
                pos: self.pos
                size: self.size
    Button:
        text: '-'
        font_size: 100                  
                  ''')

ScoreApp().run()