5 Best Ways to Adjust Window Size in Kivy with Python

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💡 Problem Formulation: When working on applications using the Kivy framework in Python, developers often require the ability to set or adjust the window size to cater to their design specifications or to enhance user experience. This article aims to provide various methods to adjust the window size in Kivy, starting with a default window size and demonstrating how to programmatically change it to a new specified size.

Method 1: Using Kivy Config Settings

This method involves adjusting the window size by configuring Kivy settings before the app is run. The Config class from kivy.config is used to set the size that the window should have on startup. This is ideal for setting a fixed window size for your application.

Here’s an example:

from kivy.config import Config
Config.set('graphics', 'width', '800')
Config.set('graphics', 'height', '600')

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

class MyApp(App):
    def build(self):
        return Button(text='Hello world!')

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

The output is a window of 800 pixels by 600 pixels with a ‘Hello world!’ button.

The code snippet sets the width and height configuration of the Kivy window before the application is launched. This ensures that the window will be created with the specified dimensions when the app starts.

Method 2: Dynamically Resizing with Window Class

The Window class from kivy.core.window can be used to dynamically adjust the size of a window after the application has started. This method is useful when the application requires real-time resizing, such as responding to user actions or changes in content.

Here’s an example:

from kivy.core.window import Window
from kivy.app import App
from kivy.uix.button import Button

class MyApp(App):
    def build(self):
        button = Button(text='Click me to resize')
        button.bind(on_press=self.resize_window)
        return button
    
    def resize_window(self, instance):
        Window.size = (500, 400)

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

The output is initially the default window size, which changes to 500 pixels by 400 pixels when the button is pressed.

This snippet allows the user to change the window size by interacting with the application’s user interface. In the code, binding a button press to a function that resizes the window is demonstrated.

Method 3: Using Kivy WideString Input

Kivy offers a ‘wide’ string input in the configuration file to make adjustments to the window size. By specifying ‘width=800,height=600’ in this way, you can set the initial window size before running the application, providing simple resizing without detailed API calls.

Here’s an example:

from kivy.config import Config
Config.read('config.ini')
# config.ini contains: [graphics]\nwidth=800\nheight=600

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

class MyApp(App):
    def build(self):
        return Label(text='Resized Window')

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

The output is a window with dimensions 800 pixels in width and 600 pixels in height displaying a label that reads ‘Resized Window’.

This code snippet shows how Kivy reads from a configuration file to determine the window size. The application then reflects these dimensions on launch.

Method 4: Fullscreen Mode or Custom Sizing

You can toggle fullscreen mode or set a custom size for the Kivy window using Window class properties. Fullscreen mode can be useful for applications or games that should take up the entire screen, whereas custom sizing gives more precision over the window dimensions.

Here’s an example:

from kivy.core.window import Window
from kivy.app import App
from kivy.uix.label import Label

class MyApp(App):
    def build(self):
        return Label(text='Fullscreen or custom size')
    
    def on_start(self):
        Window.fullscreen = 'auto'  # Toggle fullscreen mode
        # OR for custom size:
        # Window.size = (1024, 768)

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

The output is a fullscreen window or a window of 1024 pixels by 768 pixels (depending on the comment).

Here, we have the option to either run the application in fullscreen mode or specify custom dimensions, demonstrating how to accommodate varying requirements for window size.

Bonus One-Liner Method 5: Inline Size Declaration

Lastly, you can declare the size inline at the point of creating the Window instance in a single code line using size hint properties. This straightforward approach is a quick setting for fixed-size applications.

Here’s an example:

from kivy.app import App
from kivy.uix.widget import Widget

class MyWidget(Widget):
    pass

class MyApp(App):
    def build(self):
        return MyWidget(size=(300, 200))

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

The output is a window that contains a widget which is 300 pixels wide and 200 pixels tall.

The code example creates a Kivy window where the size is specified in the instance of the MyWidget class, effectively setting the window size in a concise manner.

Summary/Discussion

  • Method 1: Config Settings. Simple and effective for predefined sizes. Not suitable for dynamic resizing.
  • Method 2: Window Class. Flexible for dynamic resizing. Requires event handling and method binding.
  • Method 3: WideString Input. Streamlined configuration via external settings file. Limited to initial setup.
  • Method 4: Fullscreen & Custom Size Properties. Versatile for either fullscreen or specified dimensions. May not suit all application designs due to the lack of dynamic resizing.
  • Bonus Method 5: Inline Size Declaration. Quick and concise. Best for widgets with fixed sizes, not the entire window.