boxlayout_animation

boxlayout_anim.py

from kivy.lang import Builder
from kivy.app import App
from kivy.animation import Animation


class MyAnim(Animation):

    def on_complete(self, widget):
        widget.expanded = not widget.expanded
        if not widget.expanded:
            widget.size_hint = (1,1)

KV = """

<MyButton@Button>:
    font_size: "30sp"
    expanded: False
    on_release:
        self.size_hint = (None, 1)
        anim = app.anim(width=self.parent.width/3 if self.expanded else self.parent.width)
        anim.start(self)


BoxLayout:
    MyButton:
        text: "test1" if self.width > 10 else ""
    MyButton:
        text: "test2" if self.width > 10 else ""
    MyButton:
        text: "test3" if self.width > 10 else ""
"""


class MyApp(App):
    anim = MyAnim

    def build(self):
        return Builder.load_string(KV)


MyApp().run()