如何使用Kivy将TextInput转换为地图视图的浮点数

from kivy.app import App
from kivy.uix.textinput import TextInput
from kivy.uix.label import Label
from kivy.uix.boxlayout import BoxLayout
from kivy.garden.mapview import MapView

class MapAppLayout(BoxLayout):
    def __init__(self, **kwargs):
        super(MapAppLayout, self).__init__(**kwargs)
        self.orientation = "vertical"
        self.text_input = TextInput(multiline=False)
        self.add_widget(self.text_input)
        self.label = Label(text="")
        self.add_widget(self.label)
        self.map_view = MapView(zoom=11)
        self.add_widget(self.map_view)
        self.text_input.bind(text=self.update_label)

    def update_label(self, instance, value):
        try:
            float_value = float(value)
            self.label.text = "输入的浮点数: {}".format(float_value)
            self.map_view.lat = float_value
            self.map_view.lon = float_value
        except ValueError:
            self.label.text = "请输入有效的浮点数"

class MapApp(App):
    def build(self):
        return MapAppLayout()

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