Kivy Aligned Text Input - halign + valign for TextInput

alignedtextinput.py

from kivy.uix.textinput import TextInput
from kivy.properties import StringProperty
import functools

DEFAULT_PADDING = 6

class AlignedTextInput(TextInput):

    halign = StringProperty('left')
    valign = StringProperty('top')

    def __init__(self, **kwargs):
        self.halign = kwargs.get("halign", "left")
        self.valign = kwargs.get("valign", "top")

        self.bind(on_text=self.on_text)

        super().__init__(**kwargs)
        
    def on_text(self, instance, value):
        self.redraw()
        
    def on_size(self, instance, value):
        self.redraw()

    def redraw(self):
        """ 
        Note: This methods depends on internal variables of its TextInput
        base class (_lines_rects and _refresh_text())
        """

        self._refresh_text(self.text)

        total_size = (x.size for x in self._lines_rects)  # Modified to handle runtime dynamic on_text
        max_size = functools.reduce(lambda x, y: [x[0] + y[0], x[1] + y[1]], total_size)
        num_lines = len(self._lines_rects)
        
        px = [DEFAULT_PADDING, DEFAULT_PADDING]
        py = [DEFAULT_PADDING, DEFAULT_PADDING]
        
        if self.halign == 'center':
            d = (self.width - max_size[0]) / 2.0 - DEFAULT_PADDING
            px = [d, d]
        elif self.halign == 'right':
            px[0] = self.width - max_size[0] - DEFAULT_PADDING
            
        if self.valign == 'middle':
            d = (self.height - max_size[1] * num_lines) / 2.0 - DEFAULT_PADDING
            py = [d, d]
        elif self.valign == 'bottom':
            py[0] = self.height - max_size[1] * num_lines - DEFAULT_PADDING

        self.padding_x = px
        self.padding_y = py

Kivy Aligned TextInput

Note: This just aligns the position of the textblock, not the text itself.

test-alignedtextinput.py

import kivy
from kivy.app import App
from kivy.uix.gridlayout import GridLayout

from . import AlignedTextInput

class AlignedTextInputApp(App):
    def build(self):
        layout = GridLayout(cols=3)
        
        layout.add_widget(self.get_input('top', 'left'))
        layout.add_widget(self.get_input('top', 'center'))
        layout.add_widget(self.get_input('top', 'right'))

        layout.add_widget(self.get_input('middle', 'left'))
        layout.add_widget(self.get_input('middle', 'center'))
        layout.add_widget(self.get_input('middle', 'right'))

        layout.add_widget(self.get_input('bottom', 'left'))
        layout.add_widget(self.get_input('bottom', 'center'))
        layout.add_widget(self.get_input('bottom', 'right'))

            
        return layout
    def get_input(self, v, h):
        return AlignedTextInput(text='Example Text', halign=h, valign=v)
            

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