How to set kivy font size inside a label or a button so it fill the label or the button even the label or the button size changes

Question

I am trying to build an application with buttons (similar to the calculator), everything was good until I tries to make the app window thinner, the text go out the borders of the button. I tried font_size: self.width/5 to change the font with the screen size but it works in one situation (width or height) I also found a code

from kivy.app import App
from kivy.lang import Builder
from kivy.properties import StringProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.image import Image
from kivy.uix.label import Label


class MyLabel(Image):
    text = StringProperty('')

    def on_text(self, *_):
        # Just get large texture:
        l = Label(text=self.text)
        l.font_size = '1000dp'  # something that'll give texture bigger than phone's screen size
        l.texture_update()
        # Set it to image, it'll be scaled to image size automatically:
        self.texture = l.texture


class RootWidget(BoxLayout):
    pass


class TestApp(App):
    def build(self):
        return MyLabel(text='Test test test')


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

that solved this problem but it was using Image in kivy and I don't know how to use it in my situation or in the kv file.

Currently texts are like this:
Problem image

THANKS!

score 1 · Accepted Answer · answered Jun 15 '22 at 16:31

You can use kivy.core.text.Label to calculate sizes of rendered text, and adjust the font size to make the text fit the Label. Here is a custom Label class that does it:

from kivy.core.text import Label as CoreLabel
from kivy.core.text.markup import MarkupLabel

def MyLabel(Label):
    # this Label automatically adjusts font size to fill the Label
    def on_text(self, instance, new_text):
        self.adjust_font_size()

    def on_size(self, instance, new_size):
        self.adjust_font_size()

    def adjust_font_size(self):
        font_size = self.font_size
        while True:
            # this loops reduces font size if needed
            if self.markup:
                cl = MarkupLabel(font_name=self.font_name, font_size=font_size, text=self.text)
            else:
                cl = CoreLabel(font_name=self.font_name, font_size=font_size, text=self.text)
            cl.refresh()
            if font_size > self.height - self.padding_y * 2:
                font_size = self.height - self.padding_y * 2
            elif cl.content_width > self.width - self.padding_x * 2 or \
                    cl.content_height > self.height - self.padding_y * 2:
                font_size *= 0.95
            else:
                break
        while True:
            # this loop increases font size if needed
            if self.markup:
                cl = MarkupLabel(font_name=self.font_name, font_size=font_size, text=self.text)
            else:
                cl = CoreLabel(font_name=self.font_name, font_size=font_size, text=self.text)
            cl.refresh()
            if cl.content_width * 1.1 < self.width - self.padding_x * 2 and \
                    cl.content_height * 1.1 < self.height - self.padding_y * 2:
                font_size *= 1.05
            else:
                break

        self.font_size = font_size

I am sorry sir, but I still don't know how to use it, could you tell me the name of this concept to study it first, or you can help me more if you can and apply this way to this code for example ######################################################## `from kivy.app import App from kivy.uix.label import Label class MyLabel(Label): text = 'HelloWorld!' font_size = 50 class MyApp(App): def build(self): return MyLabel() if __name__ == "__main__": MyApp().run() ` — Mohanad Medhat, Jun 16 '22 at 12:21
In the code that you posted in your original question, just replace the `MyLabel` class with the `MyLabel` class in my answer. — John Anderson, Jun 16 '22 at 12:49
okaay, I got it. Can you do the same thing but in kv language? — Mohanad Medhat, Jun 16 '22 at 17:49

How to set kivy font size inside a label or a button so it fill the label or the button even the label or the button size changes

1 Answers1