Kivy

is a cross-platform GUI Python Framework

Install

With a virtual environment active, install with python -m pip install kivy[base] kivy_examples

UI

UI is defined in widgets with Layout, like: * BoxLayout * FloatLayout * GridLayout

KV Language

KV Language can be used to separate interface design from logic. The logic:

from kivy.app import App
from kivy.uix.button import Button

class ButtonApp(App):
    def build(self):
        return Button()

    def on_press_button(self):
        print('You pressed the button!')

if __name__ == '__main__':
    app = ButtonApp()
    app.run()

The interface in a file named button.kv:

<Button>:
    text: 'Press me'
    size_hint: (.5, .5)
    pos_hint: {'center_x': .5, 'center_y': .5}
    on_press: app.on_press_button()

Events

Buttons

from kivy.app import App
from kivy.uix.button import Button

class MainApp(App):
    def build(self):
        button = Button(text='Hello from Kivy',
                        size_hint=(.5, .5),
                        pos_hint={'center_x': .5, 'center_y': .5})
        button.bind(on_press=self.on_press_button)

        return button

    def on_press_button(self, instance):
        print('You pressed the button!')

if __name__ == '__main__':
    app = MainApp()
    app.run()

Images

from kivy.uix.image import Image
#...
img = Image(source='/path/to/real_python.png',
            size_hint=(1, .5),
            pos_hint={'center_x':.5, 'center_y':.5})
return img

Kivy examples

from kivy.app import App
from kivy.uix.label import Label

class MainApp(App):
    def build(self):
        label = Label(text='Hello from Kivy',                       # Create a label
                      size_hint=(.5, .5),                           
                      pos_hint={'center_x': .5, 'center_y': .5})    # Positions are between 0 and 1

        return label

if __name__ == '__main__':
    app = MainApp()         # Instantiate the MainApp class
    app.run()

Publish application

Android

1. pip install buildozer or python -m pip buildozer
2. buildozer init to create default buildozer.spec file