如何用PyQt5创建具有气泡效果的仿微信聊天界面？

import sys
import random
from PyQt5 import QtCore, QtGui, QtWidgets

class ChatItem(QtWidgets.QWidget):
    User_Me = 0
    User_Other = 1
    User_System = 2

    def __init__(self, text, time, user_type, parent=None):
        super(ChatItem, self).__init__(parent)
        self.text = text
        self.time = time
        self.user_type = user_type
        self.setupUI()

    def setupUI(self):
        self.setFixedSize(self.calculateSize())

        mainLayout = QtWidgets.QVBoxLayout()
        mainLayout.setContentsMargins(0, 0, 0, 0)
        self.setLayout(mainLayout)

        self.textLabel = QtWidgets.QLabel(self.text)
        self.textLabel.setWordWrap(True)
        self.textLabel.setStyleSheet(self.getStyle()) # 应用样式
        mainLayout.addWidget(self.textLabel)

        self.timeLabel = QtWidgets.QLabel(self.time)
        self.timeLabel.setAlignment(QtCore.Qt.AlignRight)
        mainLayout.addWidget(self.timeLabel)


    def calculateSize(self):
        fm = QtGui.QFontMetrics(self.textLabel.font())
        textWidth = fm.boundingRect(self.text).width() + 10
        textHeight = fm.boundingRect(self.text).height() + 10
        width = max(textWidth, 40)  # 最小宽度40
        height = max(textHeight, 20) # 最小高度20
        return QtCore.QSize(width, height)

    def getStyle(self):
        if self.user_type == ChatItem.User_Me:
            return "background-color: rgb(173, 216, 230); border-radius: 10px; padding: 5px;"
        elif self.user_type == ChatItem.User_Other:
            return "background-color: rgb(220, 248, 198); border-radius: 10px; padding: 5px;"
        else:  # System
            return "background-color: rgb(240, 240, 240); border-radius: 10px; padding: 5px; color: gray;"


class ChatWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(ChatWindow, self).__init__(parent)
        self.chatWidget = QtWidgets.QListWidget()
        self.chatWidget.setSpacing(0)
        self.setCentralWidget(self.chatWidget)

    def addItem(self, text, time, user_type):
        item = QtWidgets.QListWidgetItem()
        chatItem = ChatItem(text, time, user_type)
        self.chatWidget.addItem(item)
        item.setSizeHint(chatItem.sizeHint())
        self.chatWidget.setItemWidget(item, chatItem)


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    window = ChatWindow()
    window.show()

    userTypes = [ChatItem.User_Me, ChatItem.User_Other, ChatItem.User_System]

    for i in range(15):
        userType = random.choice(userTypes)
        time = QtCore.QDateTime.currentDateTime().toString("hh:mm")
        text = "Message from " + ["Me", "Other", "System"][userType]
        window.addItem(text, time, userType)

    sys.exit(app.exec_())