运行KivyMD+OpenCV代码遇导入错误及python3命令未识别求解决

在VSCode中运行结合KivyMD与OpenCV的代码时遇到两个问题：

1. 触发导入错误：ImportError: cannot import name 'MDBoxLayout' from 'kivy.uix.boxlayout'
2. 执行重装KivyMD的命令python3 -m pip install --force-reinstall git+https://github.com/HeaTTheatR/KivyMD.git时，提示“python3 未被识别为可执行命令”

相关代码 #

from kivymd.app import MDApp
from kivy.uix.boxlayout import MDBoxLayout
from kivy.uix.button import MDRaisedButton
from kivy.uix.image import Image
from kivy.clock import Clock
import cv2
import kivy
kivy.require('1.0.6') # replace with your current kivy version ! 

class MainApp(MDApp):
    def build(self):
        layout = MDBoxLayout(orientation='vertical')
        self.image = Image()
        layout.add_widget(self.image)
        self.save_img_button = MDRaisedButton(
            text="CLICK HERE",
            pos_hint = {'center_x':.5, 'center_y':.5},
            size_hint = (None, None))
        self.save_img_button.bind(on_press=self.take_picture)
        layout.add_widget(self.save_img_button)
        self.capture = cv2.VideoCapture(0)
        Clock.schedule_interval(self.load_video, 1.0/30.0)
        return layout
    
    def load_video(self, *args):
        ret, frame = self.capture.read()
        # Frame initialize
        self.image_frame = frame
        buffer = cv2.flip(frame, 0).tostring()
        texture = texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt = 'bgr')
        texture.blit_buffer(buffer, colorfmt='bgr', bufferfmt='ubyte')
        self.image.texture = texture

    def take_picture(self, *args):
        image_name = "picture_at_2_02.png"
        cv2.imwrite(image_name, self.image_frame)
    

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

错误回溯信息 #

Traceback (most recent call last): File "C:\Kivy\main.py", line 2, in <module> from kivy.uix.boxlayout import MDBoxLayout ImportError: cannot import name 'MDBoxLayout' from 'kivy.uix.boxlayout'

问题1：MDBoxLayout导入错误 #

MDBoxLayout和MDRaisedButton是KivyMD专属组件，不属于原生Kivy库，需修正导入路径：

• 原错误导入：

  from kivy.uix.boxlayout import MDBoxLayout
  from kivy.uix.button import MDRaisedButton
  

• 修改为正确路径：

  from kivymd.uix.boxlayout import MDBoxLayout
  from kivymd.uix.button import MDRaisedButton
  

另外，代码中texture.create未导入对应模块，需补充导入并修正调用：

from kivy.graphics.texture import Texture

将texture.create改为Texture.create。

修正后的完整导入代码：

from kivymd.app import MDApp
from kivymd.uix.boxlayout import MDBoxLayout
from kivymd.uix.button import MDRaisedButton
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
import cv2
import kivy
kivy.require('1.0.6') # 替换成你当前的kivy版本

问题2：python3命令未识别 #

Windows系统默认使用python而非python3作为命令，替换为以下命令即可：

python -m pip install --force-reinstall git+https://github.com/HeaTTheatR/KivyMD.git

若仍无法执行，可尝试使用Windows Python Launcher命令：

py -3 -m pip install --force-reinstall git+https://github.com/HeaTTheatR/KivyMD.git

内容的提问来源于stack exchange，提问作者조하여