有一个内部TextInput._get_text_width方法可用于计算适当的填充:

There is an internal TextInput._get_text_width method you can use to calculate proper padding:

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.lang import Builder

Builder.load_string('''

<MyWidget>:
    TextInput:
        multiline: False
        on_text: root.update_padding(args[0])
        padding_x: self.width/2 # initial padding
''')

class MyWidget(FloatLayout):
    def update_padding(self, text_input, *args):
        text_width = text_input._get_text_width(
            text_input.text,
            text_input.tab_width,
            text_input._label_cached
        )
        text_input.padding_x = (text_input.width - text_width)/2

class MyApp(App):
    def build(self):        
        return MyWidget()

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