simple cover image / letterboxing implementation in kivy

coverimage.py

from kivy.app import App
from kivy.lang import Builder
from kivy.factory import Factory


KV = '''
FloatLayout:
    Image:
        size_hint: None, None
        source: 'landscape.png'
        pos_hint: {'center': (.5, .5)}

        taller: self.image_ratio > (root.width / root.height)

        width: (root.height * self.image_ratio) if self.taller else root.width
        height: (root.width / self.image_ratio)  if not self.taller else root.height

        allow_stretch:True
'''


class Application(App):
    def build(self):
        return Builder.load_string(KV)


if __name__ == "__main__":
    Application().run()