Kivy tutorial - example of using Matplotlib in Kivy app

We want to be in our GUI It is common to add a data visualization module to an application . stay Kivy in , have access to garden.matplotlib To achieve . However, there is no good example to illustrate how to use it in practical applications . I am here stackoverflow I met this post on , And think this is a good example , Can be used as a template . So I updated the code based on the answers and comments to make it work . You can find the following gif View details in ：

from kivy.properties import ObjectProperty
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.app import MDApp
from kivymd.uix.expansionpanel import MDExpansionPanel, MDExpansionPanelOneLine
from kivy.uix.boxlayout import BoxLayout
import matplotlib.pyplot as plt
from kivy.garden.matplotlib.backend_kivyagg import FigureCanvasKivyAgg
from kivy.uix.image import Image
from kivy.lang import Builder

kv_str = """
<WindowManager>:
    LoginWindow:
    TravelManagerWindow:

<LoginWindow>:
    name: 'login'
    MDRaisedButton:
        text: 'Enter'
        pos_hint: {'center_x': 0.5, '