Kivy Scaling Text Based On Window Height And Width

I want to scale a text inside a button or label based on the window height, but limited by window width. The following works: font_size: self.height - dp(15) However the text can

Solution 1:

You can use a scale transformation to shrink the text if it is too large, which will avoid the race:

<ScaleLabel@Label>:
    _scale: 1. if self.texture_size[0] < self.width else float(self.width) / self.texture_size[0]
    canvas.before:
        PushMatrix
        Scale:
            origin: self.center
            x: self._scale or1.
            y: self._scale or1.
    canvas.after:
        PopMatrix

This does scale everything on the canvas, however. So if you're trying to draw a background or something, make sure it is outside the PushMatrix/PopMatrix. For example, if you wanted to use this with a Button, you could rewrite Button's kv rules:

<-ScaleButton@Button>:
    state_image: self.background_normal if self.state == 'normal'else self.background_down
    disabled_image: self.background_disabled_normal if self.state == 'normal'else self.background_disabled_down
    _scale: 1.if self.texture_size[0] < self.width elsefloat(self.width) / self.texture_size[0]
    canvas:
        Color:
            rgba: self.background_color
        BorderImage:
            border: self.border
            pos: self.pos
            size: self.size
            source: self.disabled_image if self.disabled else self.state_image
        PushMatrix
        Scale:
            origin: self.center
            x: self._scale or1.
            y: self._scale or1.
        Color:
            rgba: self.disabled_color if self.disabled else self.color
        Rectangle:
            texture: self.texture
            size: self.texture_size
            pos: int(self.center_x - self.texture_size[0] / 2.), int(self.center_y - self.texture_size[1] / 2.)
        PopMatrix

I created a usage example as a gist: https://gist.github.com/kived/862db38078170ec0ef83