|-- main.py
|-- res
| `-- fish.jpg
`-- ui
 `-- app_widget.py

import sys

from PyQt5.QtWidgets import QApplication

from ui.app_widget import AppQWidget

if __name__ == '__main__':
 app = QApplication(sys.argv)
 w = AppQWidget()
 w.show()

 sys.exit(app.exec_())

from PyQt5.QtCore import QCoreApplication
from PyQt5.QtGui import QIcon
from PyQt5.QtWidgets import QWidget, QPushButton, QDesktopWidget, QMessageBox


class AppQWidget(QWidget):
 """
 A custom QWidget by Rust Fisher
 """

 def __init__(self):
  super().__init__()
  self.init_ui()

 def init_ui(self):
  # self.setGeometry(300, 300, 400, 200) # 相当于move和resize
  self.resize(300, 200)
  self.move_to_center()
  self.setWindowTitle('Demo1')
  self.setWindowIcon(QIcon('res/fish.jpg'))

  btn1 = QPushButton('Quit', self)
  btn1.setToolTip('Click to quit')
  btn1.resize(btn1.sizeHint())
  btn1.move(200, 150)
  btn1.clicked.connect(QCoreApplication.instance().quit) # cannot locate function connect

 def closeEvent(self, event):
  reply = QMessageBox.question(self, 'Message',
          'Are you sure to quit now?',
          QMessageBox.Yes | QMessageBox.No,
          QMessageBox.No)
  if reply == QMessageBox.Yes:
   event.accept()
  else:
   event.ignore()

 def move_to_center(self):
  qr = self.frameGeometry()
  cp = QDesktopWidget().availableGeometry().center() # got center info here
  qr.moveCenter(cp)
  self.move(qr.topLeft()) # 应用窗口的左上方的点到qr矩形的左上方的点，因此居中显示在我们的屏幕上

 # 同组的控件可以存在同一个list中
 self.cb_list = [
  self.ma.i2cCB,
  self.ma.mipiCB,
  self.ma.eepromCB,
  self.ma.tem_sensorCB,
  self.ma.lensCB,
  self.ma.vcmCB,
  self.ma.mirrorCB,
  self.ma.mirrorCaliCB, ]

 self.test_count_et_list = [
  self.ma.i2cCountEt,
  self.ma.mipiCountEt,
  self.ma.eepromCountEt,
  self.ma.tem_sensorCountEt,
  self.ma.lensCountEt,
  self.ma.vcmCountEt,
  self.ma.mirrorCountEt,
  self.ma.mirrorCaliCountEt,
 ]

# 需要操作某组控件时 直接遍历列表
def _click_test_item_cb(self):
 """ Update [choose all checkbox] by all test item state """
 choose_all = True
 for cb in self.cb_list:
  choose_all = choose_all & cb.isChecked()
 self.ma.selecteAllCB.setChecked(choose_all)

>>> QtGui.QWidget()
QWidget: Must construct a QApplication before a QPaintDevice

class RustMainWindow(QMainWindow):
 """ This is the main class """

 def _trigger_english(self):
  print "Change to English", QApplication.instance()

# Change to English <PyQt4.QtGui.QApplication object at 0x02ABE3A0>

if __name__ == '__main__':
 app = QApplication(sys.argv)
 # 这里把app交给了MainWindow，MainWindow关闭时是无法正常退出应用的
 main_d = RustMainWindow(app) # 不建议这么做
 main_d.show()
 sys.exit(app.exec_())