test_car.py

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.carousel import Carousel
from kivy.uix.floatlayout import FloatLayout


Builder.load_string("""
#:import randint random.randint

<Content>
    AsyncImage:
        id: previous_image
        source: "https://lorempixel.com/output/animals-q-c-800-600-{}.jpg".format(randint(1, 5))

        canvas.before:
            StencilPush

            RoundedRectangle:
                size: root.width - dp(50), root.height - dp(50)
                pos: dp(25), dp(25)

            StencilUse

        canvas.after:
            StencilUnUse

            RoundedRectangle:
                size: root.width - dp(50), root.height - dp(50)
                pos: dp(25), dp(25)

            StencilPop
""")


class Content(FloatLayout):
    pass


class Test(App):
    def build(self):
        slider = Carousel()

        for x in range(10):
            slider.add_widget(Content())
        return slider


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