Kivy：如何创建“阻止”弹出窗口/模态视图？

Question

I did find a question on this on stackoverflow, here , but I find it just doesn't answer the question, as for me, neither the Popup nor the ModalView actually 'blocks'. What I mean is, execution is moving through a function, like:

def create_file(self):

    modal = ModalView(title="Just a moment", size_hint=(0.5, 0.5))
    btn_ok = Button(text="Save & continue", on_press=self.save_file)
    btn_no = Button(text="Discard changes", on_press=modal.dismiss)

    box = BoxLayout()
    box.add_widget(btn_ok)
    box.add_widget(btn_no)

    modal.add_widget(box)
    modal.open()

    print "back now!"
    self.editor_main.text = ""

    new = CreateView()
    new.open()

And the print statement prints "back now!" and the rest of the function is immediately executed, despite the fact the ModalView just opened. I also tried this using a Popup instead of a ModalView, with the same result. I would like execution in the function to pause while I interact with the Popup/ModalView. Is there a way for this to be done built into kivy? Must I use threads? Or will I need to just find some other workaround?

Answer 1

You can't block like that, as that would stop the event loop and you wouldn't be able to interact with your app anymore. The easiest fix is to split this into two functions, and use on_dismiss to continue:

def create_file(self):

    modal = ModalView(title="Just a moment", size_hint=(0.5, 0.5))
    btn_ok = Button(text="Save & continue", on_press=self.save_file)
    btn_no = Button(text="Discard changes", on_press=modal.dismiss)

    box = BoxLayout()
    box.add_widget(btn_ok)
    box.add_widget(btn_no)

    modal.add_widget(box)
    modal.open()
    modal.bind(on_dismiss=self._continue_create_file)

def _continue_create_file(self, *args):
    print "back now!"
    self.editor_main.text = ""

    new = CreateView()
    new.open()

It's also possible to use Twisted to make the function asynchronous, though that's a little more complicated.