Changing position of a Label in Kivy

Question

i'm new in kivy programming and while it seems that there is a lot of documentation about this problem online, i don't seem to understand any of it so i hope you could help.

I have 4 Buttons and a label, by pressing the buttons, i'm hoping to move the label in that direction. I have two variables pX and pY which are the label's position and want it to update its position each time these two are updated. Thanks in advance.

// main.py
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.widget import Widget
from kivy.graphics import Rectangle, Color
from kivy.core.window import Window
from kivy.config import Config
from kivy.uix.floatlayout import FloatLayout

Window.size = (900, 600)
Config.set('graphics', 'resizable', True)


class FloatLayout(FloatLayout):
    pX = 0.6
    pY = 0.1


class FenetreApp(App):
    def build(self):
        return FloatLayout()


FenetreApp().run()

//fenetre.kv
<Button>:
     size_hint: 0.1, 0.1
     background_color: 0.1, 0.5, 0.6, 1


<Label>:
     size_hint: 0.1, 0.1
     background_color: 1, 0, 0, 1
     canvas.before:
          Color:
               rgb: 0.1, 0.6, 0
          Rectangle:
               pos: self.pos
               size: self.size

<FloatLayout>:
     Button:
          text: "Up"
          pos_hint: {"x":0.8, "top":1}
          on_press: root.pY= root.pY +0.1
     Button:
          text: "Down"
          pos_hint: {"x":0.8, "top":0.8}
          on_press: root.pY= root.pY -0.1
     Button:
          text: "Left"
          pos_hint: {"x":0.7, "top":0.9}
          on_press: root.pX= root.pX -0.1
     Button:
          text: "Right"
          pos_hint: {"x":0.9, "top":0.9}
          on_press: root.pX= root.pX +0.1


     Label:
          name: "L1"
          text: "I wanna move"
          pos_hint: {"x":root.pY, "top":root.pY} ```

Answer 1

You need to use NumericProperty for numeric values.Otherwise, kivy doesn't update its own childrens positions, texts and other stuffs.But if you don't want to use'em, check this code. I hope its clean to understand how it works: main.py:

from kivy.app import App
from kivy.core.window import Window
from kivy.lang import Builder
Window.size = (900, 600)
kv = Builder.load_string('''
FloatLayout:
    pY: .5
    pX: .5
    Button:
        size_hint:.1,.1
        background_color: 0.1, 0.5, 0.6, 1
        text: "Up"
        pos_hint: {"x":0.8, "y":.8}
        on_press: self.parent.pY+=.1
    Button:
        size_hint:.1,.1
        background_color: 0.1, 0.5, 0.6, 1
        text: "Down"
        pos_hint: {"x":0.8, "top":0.8}
        on_press: self.parent.pY-=.1
    Button:
        size_hint:.1,.1
        background_color: 0.1, 0.5, 0.6, 1
        text: "Left"
        pos_hint: {"x":0.7, "top":0.9}
        on_press: self.parent.pX-= .1
    Button:    
        size_hint:.1,.1
        background_color: 0.1, 0.5, 0.6, 1
        text: "Right"
        pos_hint: {"x":0.9, "top":0.9}
        on_press: self.parent.pX+=.1
    Label:
        size_hint: .1,.1
        text: "I like to moving moving"
        pos_hint: {"x":self.parent.pX, "top":self.parent.pY}
''')
class sahm(App):
    def build(self):
        return kv
if __name__ == '__main__':
    sahm().run()