How to add a new button to the screen when you click on the button?

[ТН Н]

Hello! I don't quite understand how to add a new button to the screen when you click on the button, can you please explain? Here is my code, nothing happens, but it does not give an error.

from kivy.app import App

from kivy.lang import Builder

from kivy.uix.button import Button

from kivy.uix.label import Label

from kivy.uix.image import Image

from kivy.uix.widget import Widget

from kivy.uix.boxlayout import BoxLayout

from kivy.uix.screenmanager import Screen, ScreenManager, NoTransition

Builder.load_string('''

<Start>:

    BoxLayout:

        Button:

            text: '+'

            on_release: root.add_btn()

''')

class Start(Screen):

    def add_btn(self):

        layout = BoxLayout()

        btn = Button(text = 'New button')

        layout.add_widget(btn)

    

sm = ScreenManager(transition = NoTransition())

sm.add_widget(Start(name = 'one'))

class MyApp(App):  

    def build(self):

        return sm

        

MyApp().run()

[Elliot Garbus]

You were creating a layout that is not connected to the widget tree, and adding the button to it…

You can use an id to address the BoxLayout instanced in kv.  In the example below I have used the id box, and added the button to the box BoxLayout.

 

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.image import Image
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import Screen, ScreenManager, NoTransition

Builder.load_string(

'''
<Start>:
    BoxLayout:
        id: box

        Button:
            text: '+'
            on_release: root.add_btn()
'''

)


class Start(Screen):
    def add_btn(self):
        # layout = BoxLayout()
        btn = Button(text='New button')
        self.ids.box.add_widget(btn)


sm = ScreenManager(transition=NoTransition())
sm.add_widget(Start(name='one'))

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[ТН Н]

Thanks. Again, very useful.

понедельник, 8 февраля 2021 г., 0:57:42 UTC+3 пользователь ElliotG написал:

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