Kivy on Raspberry Pi 4在显示窗口之前终止

Question

当我运行Kivy应用程序时，它会提前终止。我遵循了Kivy网站上的安装说明。

主.py

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.lang import Builder
import os
os.environ['KIVY_WINDOW'] = 'sdl2'
os.environ['KIVY_GL_BACKEND'] = 'angle_sdl2'
Builder.load_file('main.kv')
class MyLayout(Widget):
pass
class TheMonitorApp(App):
def build(self):
return MyLayout()
if __name__ == '__main__':
TheMonitorApp().run

main.kv

#:kivy 2.0.0
<MyLayout>
BoxLayout:
orientation: "vertical"
size: root.width, root.height
Label:
text: "Monitor"
font_size: 32

终端

(kivy_venv) pi@raspberrypi:~/projects/HomeMonitor $ python main.py
[INFO   ] [Logger      ] Record log in /home/pi/.kivy/logs/kivy_21-11-03_19.txt
[INFO   ] [Kivy        ] v2.0.0
[INFO   ] [Kivy        ] Installed at "/home/pi/projects/HomeMonitor/kivy_venv/lib/python3.7/site-packages/kivy/__init__.py"
[INFO   ] [Python      ] v3.7.3 (default, Jan 22 2021, 20:04:44) 
[GCC 8.3.0]
[INFO   ] [Python      ] Interpreter at "/home/pi/projects/HomeMonitor/kivy_venv/bin/python"
[INFO   ] [Factory     ] 186 symbols loaded
[INFO   ] [ImageLoaderFFPy] Using ffpyplayer 4.3.2
[INFO   ] [Image       ] Providers: img_tex, img_dds, img_sdl2, img_pil, img_ffpyplayer 
(kivy_venv) pi@raspberrypi:~/projects/HomeMonitor $ 

注意终端输出停止在"0"；[INF][Image]"；，为什么它停在这里？它仍然需要达到"；窗口"；以及"；GL"；。

此外，如果我删除这些行，没有任何变化：

import os
os.environ['KIVY_WINDOW'] = 'sdl2'
os.environ['KIVY_GL_BACKEND'] = 'angle_sdl2'

Answer 1

检查：https://kivy.org/doc/stable/gettingstarted/installation.html#installation-规范

安装依赖项："对于Raspberry Pi，在安装上面的Kivy之前，您必须另外安装源依赖项中列出的依赖项">

安装kivy：python-m pip install kivy〔base〕kivy_examples