Kivy Tutorial #4: Using FloatLayout in Kivy

In this tutorial, we will learn about the FloatLayout in Kivy. FloatLayout is one of the layout managers in Kivy that allows you to position widgets using relative or absolute coordinates. It is a powerful layout that enables you to create dynamic and responsive user interfaces in your Kivy applications.

Let’s start by creating a new Kivy application with a FloatLayout as the root widget. Here’s the code for our main.py file:

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout

class FloatLayoutApp(App):
    def build(self):
        layout = FloatLayout()
        return layout

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

In the above code, we have created a FloatLayoutApp class that inherits from the App class. In the build() method, we create an instance of the FloatLayout class and return it as the root widget of our application.

Now, let’s add some widgets to our FloatLayout. We can position widgets using x and y coordinates, which are relative to the top-left corner of the layout. We can also use size_hint to specify the size of widgets relative to the size of the layout.

Here’s an example of how to add a Button widget to our FloatLayout with absolute positioning:

from kivy.uix.button import Button

class FloatLayoutApp(App):
    def build(self):
        layout = FloatLayout()

        button = Button(text='Hello, World!', size_hint=(None, None),
                        pos=(100, 100))
        layout.add_widget(button)

        return layout

In the above code, we create a Button widget with the text ‘Hello, World!’ and set its size_hint to None (meaning that the size of the widget will be fixed) and its position to (100, 100) on the layout.

We can also use size_hint to specify the size of widgets relative to the size of the layout. Here’s an example of how to add a Label widget to our FloatLayout with relative sizing:

from kivy.uix.label import Label

class FloatLayoutApp(App):
    def build(self):
        layout = FloatLayout()

        label = Label(text='Hello, Kivy!', size_hint=(.5, .5),
                      pos_hint={'center_x': .5, 'center_y': .5})
        layout.add_widget(label)

        return layout

In the above code, we create a Label widget with the text ‘Hello, Kivy!’ and set its size_hint to (.5, .5) (meaning that the widget will take up half of the width and height of the layout) and its position_hint to center the widget in the middle of the layout.

FloatLayout also supports adding widgets with dynamic sizing using size_hint_min, size_hint_max, and size_hint_x/y properties, which can be useful for creating responsive layouts that adapt to different screen sizes.

Overall, FloatLayout is a versatile layout manager in Kivy that allows you to position widgets with absolute or relative coordinates, making it easy to create dynamic and responsive user interfaces in your Kivy applications. Experiment with different positioning and sizing techniques to create unique and visually appealing layouts for your Kivy projects.