怎么样使用python3+PyQt5实现使用剪贴板做复制与粘帖功能？

#!/usr/bin/env python3
import os
import sys
from PyQt5.QtCore import (QMimeData, Qt)
from PyQt5.QtWidgets import (QApplication, QDialog, QGridLayout, QLabel,
  QPushButton)
from PyQt5.QtGui import QPixmap

class Form(QDialog):

 def __init__(self, parent=None):
  super(Form, self).__init__(parent)

  textCopyButton = QPushButton("&Copy Text")
  textPasteButton = QPushButton("Paste &Text")
  htmlCopyButton = QPushButton("C&opy HTML")
  htmlPasteButton = QPushButton("Paste &HTML")
  imageCopyButton = QPushButton("Co&py Image")
  imagePasteButton = QPushButton("Paste &Image")
  self.textLabel = QLabel("Original text")
  self.imageLabel = QLabel()
  self.imageLabel.setPixmap(QPixmap(os.path.join(
    os.path.dirname(__file__), "images/clock.png")))

  layout = QGridLayout()
  layout.addWidget(textCopyButton, 0, 0)
  layout.addWidget(imageCopyButton, 0, 1)
  layout.addWidget(htmlCopyButton, 0, 2)
  layout.addWidget(textPasteButton, 1, 0)
  layout.addWidget(imagePasteButton, 1, 1)
  layout.addWidget(htmlPasteButton, 1, 2)
  layout.addWidget(self.textLabel, 2, 0, 1, 2)
  layout.addWidget(self.imageLabel, 2, 2)
  self.setLayout(layout)

  textCopyButton.clicked.connect(self.copyText)
  textPasteButton.clicked.connect(self.pasteText)
  htmlCopyButton.clicked.connect(self.copyHtml)
  htmlPasteButton.clicked.connect(self.pasteHtml)
  imageCopyButton.clicked.connect(self.copyImage)
  imagePasteButton.clicked.connect(self.pasteImage)

  self.setWindowTitle("Clipboard")


 def copyText(self):
  clipboard = QApplication.clipboard()
  clipboard.setText("I've been clipped!")


 def pasteText(self):
  clipboard = QApplication.clipboard()
  self.textLabel.setText(clipboard.text())


 def copyImage(self):
  clipboard = QApplication.clipboard()
  clipboard.setPixmap(QPixmap(os.path.join(
    os.path.dirname(__file__), "images/gvim.png")))

 def pasteImage(self):
  clipboard = QApplication.clipboard()
  self.imageLabel.setPixmap(clipboard.pixmap())


 def copyHtml(self):
  mimeData = QMimeData()
  mimeData.setHtml("<b>Bold and <font color=red>Red</font></b>")
  clipboard = QApplication.clipboard()
  clipboard.setMimeData(mimeData)


 def pasteHtml(self):
  clipboard = QApplication.clipboard()
  mimeData = clipboard.mimeData()
  if mimeData.hasHtml():
   self.textLabel.setText(mimeData.html())

if __name__ == "__main__":
 app = QApplication(sys.argv)
 form = Form()
 form.show()
 app.exec_()