Python - Kivy - touch and collide_point

# Kivy sends `on_touch_down` events to all widgets
# so every widget has to check if touch was made in widget's area.
# Or you have to use `on_press` or `on_release` instead `on_touch_down`
# https://stackoverflow.com/a/45942518/1832058


#--- calc.kv ---

#:kivy 1.10.0

<Calculate>:
    display: entry
    rows: 5
    padding: 10
    spacing: 10

    BoxLayout:
        TextInput:
            id: entry
            multiline: False
            font_size: 32
            text: "Kivy Touch: "

    BoxLayout:
        spacing: 10

        Button:
            font_size: 20
            text: '7'
            on_press: entry.text += self.text

        Button:
            font_size: 20
            text: '8'
            on_release: entry.text += self.text

        Button:
            font_size: 20
            text: '9'
            on_touch_down: root.touch_button(*args)

        Button:
            font_size: 20
            text: '+'
            on_touch_down: root.touch_button(*args)

#--- calc.py ---

#!/usr/bin/env python3

from kivy.app import App
from kivy.uix.gridlayout import GridLayout


# kivy sends `on_touch_down` events to all widgets
# so every widget has to check if touch was made in widget's area.
# Or you have to use `on_press` or `on_release` instead `on_touch_down`
# https://stackoverflow.com/a/45942518/1832058


class Calculate(GridLayout):

    def touch_button(self, instance, touch, *args):
        if instance.collide_point(*touch.pos):
            self.ids.entry.text += instance.text
            return False # don't send event to other buttons


class CalcApp(App):
    def build(self):
        return Calculate()


if __name__ == '__main__':
    CalcApp().run()