按下按钮时替换Kivy中的DataFrame图

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.widget import Widget
from kivy.graphics import Color, Rectangle
import pandas as pd
import matplotlib.pyplot as plt
from io import BytesIO
from PIL import Image

class DataFrameGraphWidget(Widget):
    def __init__(self, **kwargs):
        super(DataFrameGraphWidget, self).__init__(**kwargs)
        self.data_frame = pd.DataFrame({'A': range(10), 'B': range(10, 20)})
        self.update_graph()

    def update_graph(self):
        buf = BytesIO()
        plt.figure()
        self.data_frame.plot(kind='line')
        plt.savefig(buf, format='png')
        buf.seek(0)
        img = Image.open(buf)
        with self.canvas:
            self.canvas.clear()
            Color(1, 1, 1, 1)
            Rectangle(pos=self.pos, size=self.size, source=img)

class MainApp(App):
    def build(self):
        layout = BoxLayout(orientation='vertical')
        self.graph_widget = DataFrameGraphWidget(size_hint_y=None, height=400)
        button = Button(text='Replace Graph')
        button.bind(on_press=self.replace_graph)
        layout.add_widget(self.graph_widget)
        layout.add_widget(button)
        return layout

    def replace_graph(self, instance):
        # 这里可以替换为新的DataFrame
        self.graph_widget.data_frame = pd.DataFrame({'C': range(20), 'D': range(20, 40)})
        self.graph_widget.update_graph()

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