kivy/examples/cover/cover_image.py

import kivy
from kivy.app import App
from kivy.uix.behaviors import CoverBehavior
from kivy.uix.image import Image


class CoverImage(CoverBehavior, Image):
    """Image using cover behavior.
    """

    def __init__(self, **kwargs):
        super(CoverImage, self).__init__(**kwargs)
        texture = self._coreimage.texture
        self.reference_size = texture.size
        self.texture = texture


class MainApp(App):

    def build(self):
        return CoverImage(source='../widgets/cityCC0.png')


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