PySide2 MainWindow类内QTimer/按钮无法调用函数问题求助

我在使用PySide2的QMainWindow类时，遇到timer.timeout.connect()无法正常调用类内displayFrame函数的问题（按钮clicked.connect调用sys.exit正常，但调用自定义类函数存在异常）。此前未封装到MainWindow类中的代码可以正常运行，我的目标是通过TFLite和OpenCV将PiCamera的视频流推送到应用界面（该功能在非类封装版本中曾正常工作）。

故障代码 #

from PySide2.QtCore import *
from PySide2.QtGui import *
from PySide2.QtWidgets import QApplication, QWidget, QLabel, QPushButton, QVBoxLayout, QMainWindow
import cv2 
import qimage2ndarray 
import sys 
import time
import os
import argparse
from tflite_support.task import core
from tflite_support.task import processor
from tflite_support.task import vision
from picamera2 import Picamera2, MappedArray, Preview
import utils
from imutils.video import VideoStream
import imagezmq
import socket
from libcamera import controls

class MainWindow(QMainWindow):
   def __init__(self):
      super(MainWindow, self).__init__()
      self.setWindowTitle("My App")
      self.setFixedSize(QSize(480, 320))
      timer = QTimer()
      timer.timeout.connect(self.displayFrame)
      timer.start(30)
      
      
      button = QPushButton("Quiter")
      label = QLabel('No Camera Feed')
      
      button.clicked.connect(sys.exit) # 此调用正常工作
      layout = QVBoxLayout()
      layout.addWidget(button)
     
      layout.addWidget(label)
      
      widget = QWidget()
      widget.setLayout(layout)
      self.setCentralWidget(widget)
   
   def testing(self):
         print("hello")
   
   def displayFrame(self):
      print("hello") # 连这句都不打印
      frame = picam2.capture_array("main")
      frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
      input_tensor = vision.TensorImage.create_from_array(frame)
      detection_result = detector.detect(input_tensor)
      image = utils.visualize(frame, detection_result)
      sender.send_image(rpiName, image)
      image = qimage2ndarray.array2qimage(frame)
      label.setPixmap(QPixmap.fromImage(image))
      
     
app = QApplication([])
window = MainWindow()
window.show()
app.exec_()

此前正常运行的非类封装代码 #

def displayFrame():
   frame = picam2.capture_array("main")
   frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
   input_tensor = vision.TensorImage.create_from_array(frame)
   detection_result = detector.detect(input_tensor)
   image = utils.visualize(frame, detection_result)
   sender.send_image(rpiName, image)
   image = qimage2ndarray.array2qimage(frame)
   label.setPixmap(QPixmap.fromImage(image))
   

app = QApplication([])
window = QWidget()

timer = QTimer()
timer.timeout.connect(displayFrame)
timer.start(30)
label = QLabel('No Camera Feed')
button = QPushButton("Quiter")
button.clicked.connect(sys.exit)
layout = QVBoxLayout()
layout.addWidget(button)
layout.addWidget(label)
window.setLayout(layout)
window.show()
app.exec_()

测试可用的代码（仅调用简单测试函数） #

class MainWindow(QMainWindow):
   def __init__(self):
      super(MainWindow, self).__init__()
      self.setWindowTitle("My App")
      self.setFixedSize(QSize(480, 320))
      self.timer = QTimer()
      self.timer.timeout.connect(self.testing) # 此处本应使用self.displayFrame
      self.timer.start(30)
      
      
      button = QPushButton("Quiter")
      label = QLabel('No Camera Feed')
      
      button.clicked.connect(sys.exit) # 退出按钮正常工作
      layout = QVBoxLayout()
      layout.addWidget(button)
     
      layout.addWidget(label)
      
      widget = QWidget()
      widget.setLayout(layout)
      self.setCentralWidget(widget)
   
   def testing(self):
         print("hello")

问题现象 #

• 上述测试代码中，终端会每30毫秒打印一次"hello"，说明定时器和信号连接逻辑正常。
• 但将self.testing改为self.displayFrame后，应用启动后立即无响应，按钮和标签均不显示，界面处于卡死状态。

内容的提问来源于stack exchange，提问作者FireFalcon3469