将CheckBox添加到Canva Kivy

from kivy.app import App
from kivy.uix.checkbox import CheckBox
from kivy.uix.widget import Widget
from kivy.graphics import Color, Rectangle

class CanvasWidget(Widget):
    def __init__(self, **kwargs):
        super(CanvasWidget, self).__init__(**kwargs)
        
        # 创建一个CheckBox实例
        self.checkbox = CheckBox()
        self.checkbox.pos = (100, 100)  # 设置CheckBox的位置
        self.checkbox.size_hint = (None, None)  # 取消自动调整大小
        
        # 将CheckBox添加到Canvas中
        self.canvas.add(self.checkbox)
        
        # 绘制Canvas背景
        with self.canvas:
            Color(0.5, 0.5, 0.5, 1)  # 设置颜色为灰色
            Rectangle(pos=self.pos, size=self.size)  # 绘制矩形背景

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

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