from kivy.lang import Builder
from kivy.base import runTouchApp

KV = '''

<-ScaleButton@Button>:
    x_ratio: min(1, self.width / (self.texture_size[0] or 1))
    y_ratio: min(1, self.height / (self.texture_size[1] or 1))
    min_ratio: min(self.x_ratio or 1, self.y_ratio or 1)
    keep_ratio: False
    scale_x: (self.min_ratio or 1) if self.keep_ratio else self.x_ratio or 1
    scale_y: (self.min_ratio or 1) if self.keep_ratio else self.y_ratio or 1

    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

    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
        Color:
            rgba: 1, 1, 1, 1

        PushMatrix
        Scale:
            x: self.scale_x or 1
            y: self.scale_y or 1

        Rectangle:
            texture: self.texture
            size: self.texture_size
            pos:
                (
                int((self.center_x / (self.scale_x or 1)) - self.texture_size[0] / 2.),
                int((self.center_y / (self.scale_y or 1)) - self.texture_size[1] / 2.)
                )

        PopMatrix


FloatLayout:
    ScaleButton:
        text: 'test ' * 5
        font_size: font_size.value
        size_hint: size_hint_x.value, size_hint_y.value
        pos_hint: {'center': (.5, .5)}
        keep_ratio: lock_ratio.active

    Slider:
        id: size_hint_y
        orientation: 'vertical'
        size_hint_x: None
        value: .5
        min: 0
        max: 1

    Slider:
        id: size_hint_x
        size_hint_y: None
        value: .5
        min: 0
        max: 1

    Slider:
        id: font_size
        orientation: 'vertical'
        size_hint_x: None
        value: 20
        min: 10
        max: 1000
        pos_hint: {'right': 1}

    BoxLayout:
        size: self.minimum_size
        size_hint: None, None
        pos_hint: {'center': (.5, .8)}

        CheckBox:
            id: lock_ratio
            size_hint: None, None
            size: 20, 20
        Label:
            text: 'lock ratio'
            size_hint: None, None
            size: self.texture_size
'''  # noqa


runTouchApp(Builder.load_string(KV))