Qiita記事 EventDispatcherのeventを待機

main.py

from kivy.clock import Clock


def start_gen(gen):
    def step_gen(*args, **kwargs):
        try:
            gen.send((args, kwargs, ))(step_gen)
        except StopIteration:
            pass

    try:
        gen.send(None)(step_gen)
    except StopIteration:
        pass


def event(ed, name):
    bind_id = None
    step_gen = None

    def bind(step_gen_):
        nonlocal bind_id, step_gen
        bind_id = ed.fbind(name, callback)
        assert bind_id > 0  # bindingに成功したか確認
        step_gen = step_gen_

    def callback(*args, **kwargs):
        ed.unbind_uid(name, bind_id)
        step_gen(*args, **kwargs)

    return bind


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

def some_task(label):
    yield event(label, 'on_touch_down')
    label.text = 'B'
    yield event(label, 'on_touch_down')
    label.text = 'C'


KV_CODE = '''
Label:
    text: 'A'
'''

class SampleApp(App):
    def build(self):
        return Builder.load_string(KV_CODE)
    def on_start(self):
        start_gen(some_task(self.root))

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