Ytukyg

I made two buttons that have the same path to a function. Only one of the buttons works though. Both button should change the lines in the circle.

I've read on other post that I might need to 'link' the two classes together so that they can 'talk'. If anyone has any insight, please advise me!

Also, why does the print function work on both buttons but not the rest of the function?

Py:

from kivy.app import App

from kivy.properties import ListProperty

from kivy.uix.button import Button

from kivy.uix.screenmanager import ScreenManager, Screen



class Screen1(Screen):

    pass



class SM(ScreenManager):

    pass



class ButtonX(Button):

    def increaseX(self):

        TestApp().increase()



class TestApp(App):



    random_num_list = ListProperty([20, 40, 80])



    def increase(self):

        print(str(self.random_num_list))

        self.random_num_list = [90, 140, 220]



    def build(self):

        global sm

        sm = SM()

        return sm



if __name__ == '__main__':

    TestApp().run()

Kv:

<Screen1>:

    FloatLayout:

        Button:

            pos_hint: {'center_x': .5, 'center_y': .5}



            canvas:

                Color:

                    rgba: 1,1,1,1

                Line:

                    width: 5

                    circle: self.center_x, self.center_y, min(self.width, self.height) / 4, 0, app.random_num_list[0]



                Color:

                    rgba: .8,.1,.8,1

                Line:

                    width: 5

                    circle: self.center_x, self.center_y, min(self.width, self.height) / 4, app.random_num_list[0], app.random_num_list[1]



                Color:

                    rgba: .6,.6,1,1

                Line:

                    width: 5

                    circle: self.center_x, self.center_y, min(self.width, self.height) / 4, app.random_num_list[1], app.random_num_list[2]



                Color:

                    rgba: 1,.1,.4,1

                Line:

                    width: 5

                    circle: self.center_x, self.center_y, min(self.width, self.height) / 4, app.random_num_list[2], 360



        ButtonX:

            pos_hint: {'center_x': .5, 'center_y': .55}

            size_hint: .2, .1

            text: 'Try first:ndoesn't works'

            on_press: self.increaseX()



        ButtonX:

            pos_hint: {'center_x': .5, 'center_y': .45}

            size_hint: .2, .1

            text: 'Try second:nworks'

            on_press: app.increase()

<SM>:

    Screen1:

To understand the problem I am going to modify the code:

# ...

class ButtonX(Button):

    def increaseX(self):

        t2 = TestApp()

        print("t2", t2)

        t2.increase()

# ...

if __name__ == '__main__':

    t1 = TestApp()

    print("t1", t1)

    t1.run()

Getting the following:

...

t1 <__main__.TestApp object at 0x7f8e750c38d0>

...

t2 <__main__.TestApp object at 0x7f8e71246320>

...

And clearly it is seen that they are 2 different objects, therefore when calling increase() it will not generate any modification to the current application.

In the case of .kv is used to app that is an object that indicates the application that is running, and in equivalent in .py is App.get_running_app(), so the solution is to use this last element.

from kivy.app import App

from kivy.properties import ListProperty

from kivy.uix.button import Button

from kivy.uix.screenmanager import ScreenManager, Screen



class Screen1(Screen):

    pass



class SM(ScreenManager):

    pass



class ButtonX(Button):

    def increaseX(self):

        App.get_running_app().increase() # <---



class TestApp(App):

    random_num_list = ListProperty([20, 40, 80])



    def increase(self):

        print(str(self.random_num_list))

        self.random_num_list = [90, 140, 220]



    def build(self):

        sm = SM()

        return sm



if __name__ == '__main__':

    TestApp().run()

Finally, do not use global variables because they are a headache when debugging.