test_hsv.py

from kivy.app import App
from kivy.lang import Builder
from kivy.factory import Factory


KV = '''
<NumInput@TextInput>:
    value: 0
    size_hint_y: None
    height: self.minimum_height
    multiline: False
    on_text_validate:
        if self.text.isdigit: self.value = int(self.text)
        else: self.text = ''

BoxLayout:
    GridLayout:
        pos_hint: {'center_y': .5}
        size_hint_y: None
        height: self.minimum_height
        spacing: 20
        cols: 2
        Label:
            text: 'H'
        NumInput:
            id: h
        Label:
            text: 'S'
        NumInput:
            id: s
        Label:
            text: 'V'
        NumInput:
            id: v
    Widget:
        canvas:
            Color:
                hsv: h.value / 360, s.value / 100, v.value / 100
            Rectangle:
                pos: self.pos
                size: self.size
'''


class Application(App):
    def build(self):
        return Builder.load_string(KV)


if __name__ == "__main__":
    Application().run()