PyQT：重写QComboBox控件，添加click信号

痛点：
  在读取电脑所有 COM 口时希望在点击 combobox 下拉框时能自动刷新列表
现状：
  combobox 内置的信号没有 click 相关的动作
解决：
  通过重写 combobox 中的鼠标点击事件进行实现

# -*- coding: utf-8 -*-
import sys
from PySide2 import QtCore, QtGui
from PySide2.QtWidgets import *
import serial
import serial.tools.list_ports


class MyComboBoxControl(QComboBox):
    clicked = QtCore.Signal()     # 自定义信号

    def __init__(self, Parent=None):
        super(MyComboBoxControl, self).__init__(Parent)     # 调用父类的初始化方法

    def mousePressEvent(self, event: QtGui.QMouseEvent) -> None:        # 重写鼠标按下事件
        if event.button() == QtCore.Qt.LeftButton:     # 当鼠标左键单击时
            self.clicked.emit()     # 发射信号
        QComboBox.showPopup(self)       # 弹出下拉框


class WinForm(QWidget):
    # 自定义信号，不带参数
    button_clicked_signal = QtCore.Signal()
 
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setWindowTitle('Select Com Port')
        self.combobox = MyComboBoxControl(self)
        self.combobox.addItems(['COM1'])
        self.combobox.setGeometry(QtCore.QRect(150, 20, 351, 51))
        self.resize(700, 150)
        
        # 接收信号，连接到自定义槽函数
        self.combobox.clicked.connect(self.setComPort)

    def setComPort(self):
        # QMessageBox.information(self, 'Pop messgae', 'OK')
        self.combobox.clear()
        plist = list(serial.tools.list_ports.comports())
        if len(plist) <= 0:
            self.combobox.addItem('No Com Port')
        else:   
            self.combobox.addItems('COM'+ i for i in plist)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    win = WinForm()
    win.show()
    sys.exit(app.exec_())