Untitled

from kivy.app import App
from math import sqrt
from kivy.core.window import Window
from kivy.lang.builder import Builder
from kivy.properties import NumericProperty

KV = '''
BoxLayout:
	size: self.size
	pos: self.pos
	orientation: 'vertical'
	ScrollView:
        GridLayout:
            cols: 1
            size_hint_y: None
            height: self.minimum_height
            size_hint: 1, None
			Label:
				id: label1
                halign: 'right'
                size_hint: 1, None
                height: self.texture_size[1]
                text_size: self.width, None
				text: "אבגדהוזחטיכלמנסעפצקרשתאבגדהוזחטיכלמנסעפצקרשתאבגדהוזחטיכלמנסעפצקרשתאבגדהוזחטיכלמנסעפצקרשתאבגדהוזחטיכלמנסעפצקרשתאבגדהוזחטיכלמנסעפצקרשת"
				font_name: 'DejaVuSans'
				font_size: app.font_size*80/25
				pos_hint: {"x": -0.15, "y": 0.05}
'''


class MainApp(App):
	font_size = NumericProperty()

	def __init__(self, **kwargs):
		super(MainApp, self).__init__(**kwargs)
		self.font_size = 25

	def win_cb(self, window, width, height):
		new_size = sqrt(width**2 + height**2)/40.6
		MainApp().font_size = new_size

	def build(self):
		Window.bind(on_resize=self.win_cb)
		self.screen = Builder.load_string(KV)
		return self.screen


MainApp().run()