第十四篇 -- QMainWindow与QAction（清空-全选-撤销-重做-关闭-语言选择）

效果图：

这次添加了关闭-撤销-重做-全选-清空等功能，并添加了字体和字体大小选择。基本方法跟前面几篇类似。

ui_mainWindow.py

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'ui_mainWindow.ui'
#
# Created by: PyQt5 UI code generator 5.13.0
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(691, 367)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.plainTextEdit = QtWidgets.QPlainTextEdit(self.centralwidget)
        self.plainTextEdit.setGeometry(QtCore.QRect(0, 0, 691, 291))
        font = QtGui.QFont()
        font.setPointSize(18)
        self.plainTextEdit.setFont(font)
        self.plainTextEdit.setObjectName("plainTextEdit")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 691, 21))
        self.menubar.setObjectName("menubar")
        self.menu = QtWidgets.QMenu(self.menubar)
        self.menu.setObjectName("menu")
        self.menu_2 = QtWidgets.QMenu(self.menubar)
        self.menu_2.setObjectName("menu_2")
        self.menu_3 = QtWidgets.QMenu(self.menubar)
        self.menu_3.setObjectName("menu_3")
        MainWindow.setMenuBar(self.menubar)
        self.toolBar = QtWidgets.QToolBar(MainWindow)
        self.toolBar.setToolButtonStyle(QtCore.Qt.ToolButtonIconOnly)
        self.toolBar.setObjectName("toolBar")
        MainWindow.addToolBar(QtCore.Qt.TopToolBarArea, self.toolBar)
        self.statusBar = QtWidgets.QStatusBar(MainWindow)
        self.statusBar.setObjectName("statusBar")
        MainWindow.setStatusBar(self.statusBar)
        self.actFont_Italic = QtWidgets.QAction(MainWindow)
        self.actFont_Italic.setCheckable(True)
        icon = QtGui.QIcon()
        icon.addPixmap(QtGui.QPixmap("icons/images/Italic.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actFont_Italic.setIcon(icon)
        self.actFont_Italic.setObjectName("actFont_Italic")
        self.actFont_Bold = QtWidgets.QAction(MainWindow)
        self.actFont_Bold.setCheckable(True)
        icon1 = QtGui.QIcon()
        icon1.addPixmap(QtGui.QPixmap("icons/images/Bold.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actFont_Bold.setIcon(icon1)
        self.actFont_Bold.setObjectName("actFont_Bold")
        self.actFont_Underline = QtWidgets.QAction(MainWindow)
        self.actFont_Underline.setCheckable(True)
        icon2 = QtGui.QIcon()
        icon2.addPixmap(QtGui.QPixmap("icons/images/underline.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actFont_Underline.setIcon(icon2)
        self.actFont_Underline.setObjectName("actFont_Underline")
        self.actEdit_Cut = QtWidgets.QAction(MainWindow)
        self.actEdit_Cut.setEnabled(False)
        icon3 = QtGui.QIcon()
        icon3.addPixmap(QtGui.QPixmap("icons/images/cut.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actEdit_Cut.setIcon(icon3)
        self.actEdit_Cut.setObjectName("actEdit_Cut")
        self.actEdit_Copy = QtWidgets.QAction(MainWindow)
        self.actEdit_Copy.setEnabled(False)
        icon4 = QtGui.QIcon()
        icon4.addPixmap(QtGui.QPixmap("icons/images/copy.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actEdit_Copy.setIcon(icon4)
        self.actEdit_Copy.setObjectName("actEdit_Copy")
        self.actEdit_Paste = QtWidgets.QAction(MainWindow)
        self.actEdit_Paste.setEnabled(False)
        icon5 = QtGui.QIcon()
        icon5.addPixmap(QtGui.QPixmap("icons/images/paste.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actEdit_Paste.setIcon(icon5)
        self.actEdit_Paste.setObjectName("actEdit_Paste")
        self.actFile_New = QtWidgets.QAction(MainWindow)
        icon6 = QtGui.QIcon()
        icon6.addPixmap(QtGui.QPixmap("icons/images/new.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actFile_New.setIcon(icon6)
        self.actFile_New.setObjectName("actFile_New")
        self.actFile_Open = QtWidgets.QAction(MainWindow)
        icon7 = QtGui.QIcon()
        icon7.addPixmap(QtGui.QPixmap("icons/images/open.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actFile_Open.setIcon(icon7)
        self.actFile_Open.setObjectName("actFile_Open")
        self.actFile_Save = QtWidgets.QAction(MainWindow)
        icon8 = QtGui.QIcon()
        icon8.addPixmap(QtGui.QPixmap("icons/images/save.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actFile_Save.setIcon(icon8)
        self.actFile_Save.setObjectName("actFile_Save")
        self.actClose = QtWidgets.QAction(MainWindow)
        icon9 = QtGui.QIcon()
        icon9.addPixmap(QtGui.QPixmap("icons/images/close.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actClose.setIcon(icon9)
        self.actClose.setObjectName("actClose")
        self.actEdit_Undo = QtWidgets.QAction(MainWindow)
        self.actEdit_Undo.setEnabled(False)
        icon10 = QtGui.QIcon()
        icon10.addPixmap(QtGui.QPixmap("icons/images/undo.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actEdit_Undo.setIcon(icon10)
        self.actEdit_Undo.setObjectName("actEdit_Undo")
        self.acEdit_Redo = QtWidgets.QAction(MainWindow)
        self.acEdit_Redo.setEnabled(False)
        icon11 = QtGui.QIcon()
        icon11.addPixmap(QtGui.QPixmap("icons/images/redo.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.acEdit_Redo.setIcon(icon11)
        self.acEdit_Redo.setObjectName("acEdit_Redo")
        self.actEdit_Clear = QtWidgets.QAction(MainWindow)
        icon12 = QtGui.QIcon()
        icon12.addPixmap(QtGui.QPixmap("icons/images/clear.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actEdit_Clear.setIcon(icon12)
        self.actEdit_Clear.setObjectName("actEdit_Clear")
        self.actEdit_SelectAll = QtWidgets.QAction(MainWindow)
        self.actEdit_SelectAll.setObjectName("actEdit_SelectAll")
        self.actLang_CN = QtWidgets.QAction(MainWindow)
        self.actLang_CN.setCheckable(True)
        icon13 = QtGui.QIcon()
        icon13.addPixmap(QtGui.QPixmap("icons/images/chinese.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actLang_CN.setIcon(icon13)
        self.actLang_CN.setObjectName("actLang_CN")
        self.actLang_EN = QtWidgets.QAction(MainWindow)
        self.actLang_EN.setCheckable(True)
        icon14 = QtGui.QIcon()
        icon14.addPixmap(QtGui.QPixmap("icons/images/English.jpg"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
        self.actLang_EN.setIcon(icon14)
        self.actLang_EN.setObjectName("actLang_EN")
        self.menu.addAction(self.actFile_New)
        self.menu.addAction(self.actFile_Open)
        self.menu.addAction(self.actFile_Save)
        self.menu.addSeparator()
        self.menu.addAction(self.actClose)
        self.menu_2.addAction(self.actEdit_Cut)
        self.menu_2.addAction(self.actEdit_Copy)
        self.menu_2.addAction(self.actEdit_Paste)
        self.menu_2.addSeparator()
        self.menu_2.addAction(self.actEdit_Undo)
        self.menu_2.addAction(self.acEdit_Redo)
        self.menu_2.addSeparator()
        self.menu_2.addAction(self.actEdit_SelectAll)
        self.menu_2.addAction(self.actEdit_Clear)
        self.menu_3.addAction(self.actFont_Italic)
        self.menu_3.addAction(self.actFont_Bold)
        self.menu_3.addAction(self.actFont_Underline)
        self.menu_3.addSeparator()
        self.menubar.addAction(self.menu.menuAction())
        self.menubar.addAction(self.menu_2.menuAction())
        self.menubar.addAction(self.menu_3.menuAction())
        self.toolBar.addAction(self.actFile_New)
        self.toolBar.addAction(self.actFile_Open)
        self.toolBar.addAction(self.actFile_Save)
        self.toolBar.addSeparator()
        self.toolBar.addAction(self.actEdit_Cut)
        self.toolBar.addAction(self.actEdit_Copy)
        self.toolBar.addAction(self.actEdit_Paste)
        self.toolBar.addSeparator()
        self.toolBar.addAction(self.actEdit_Undo)
        self.toolBar.addAction(self.acEdit_Redo)
        self.toolBar.addSeparator()
        self.toolBar.addAction(self.actFont_Italic)
        self.toolBar.addAction(self.actFont_Bold)
        self.toolBar.addAction(self.actFont_Underline)
        self.toolBar.addSeparator()
        self.toolBar.addAction(self.actLang_CN)
        self.toolBar.addAction(self.actLang_EN)
        self.toolBar.addSeparator()

        self.retranslateUi(MainWindow)
        self.actEdit_Cut.triggered.connect(self.plainTextEdit.cut)
        self.actEdit_Copy.triggered.connect(self.plainTextEdit.copy)
        self.actEdit_Paste.triggered.connect(self.plainTextEdit.paste)
        self.actClose.triggered.connect(MainWindow.close)
        self.actEdit_Undo.triggered.connect(self.plainTextEdit.undo)
        self.acEdit_Redo.triggered.connect(self.plainTextEdit.redo)
        self.actEdit_Clear.triggered.connect(self.plainTextEdit.clear)
        self.actEdit_SelectAll.triggered.connect(self.plainTextEdit.selectAll)
        self.plainTextEdit.undoAvailable['bool'].connect(self.actEdit_Undo.setEnabled)
        self.plainTextEdit.redoAvailable['bool'].connect(self.acEdit_Redo.setEnabled)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.menu.setTitle(_translate("MainWindow", "文件(F)"))
        self.menu_2.setTitle(_translate("MainWindow", "编辑(E)"))
        self.menu_3.setTitle(_translate("MainWindow", "格式(M)"))
        self.toolBar.setWindowTitle(_translate("MainWindow", "toolBar"))
        self.actFont_Italic.setText(_translate("MainWindow", "斜体"))
        self.actFont_Italic.setToolTip(_translate("MainWindow", "<html><head/><body><p><span style=\" font-style:italic;\">斜体</span></p></body></html>"))
        self.actFont_Bold.setText(_translate("MainWindow", "粗体"))
        self.actFont_Bold.setToolTip(_translate("MainWindow", "加粗"))
        self.actFont_Underline.setText(_translate("MainWindow", "下划线"))
        self.actFont_Underline.setToolTip(_translate("MainWindow", "下划线"))
        self.actEdit_Cut.setText(_translate("MainWindow", "剪切"))
        self.actEdit_Cut.setToolTip(_translate("MainWindow", "剪切到粘贴板"))
        self.actEdit_Cut.setShortcut(_translate("MainWindow", "Ctrl+X"))
        self.actEdit_Copy.setText(_translate("MainWindow", "复制"))
        self.actEdit_Copy.setToolTip(_translate("MainWindow", "复制到粘贴板"))
        self.actEdit_Copy.setShortcut(_translate("MainWindow", "Ctrl+C"))
        self.actEdit_Paste.setText(_translate("MainWindow", "粘贴"))
        self.actEdit_Paste.setToolTip(_translate("MainWindow", "从粘贴板粘贴"))
        self.actEdit_Paste.setShortcut(_translate("MainWindow", "Ctrl+V"))
        self.actFile_New.setText(_translate("MainWindow", "新建"))
        self.actFile_New.setToolTip(_translate("MainWindow", "新建文件"))
        self.actFile_New.setShortcut(_translate("MainWindow", "Ctrl+N"))
        self.actFile_Open.setText(_translate("MainWindow", "打开..."))
        self.actFile_Open.setToolTip(_translate("MainWindow", "打开文件"))
        self.actFile_Open.setShortcut(_translate("MainWindow", "Ctrl+O"))
        self.actFile_Save.setText(_translate("MainWindow", "保存"))
        self.actFile_Save.setToolTip(_translate("MainWindow", "保存修改"))
        self.actFile_Save.setShortcut(_translate("MainWindow", "Ctrl+S"))
        self.actClose.setText(_translate("MainWindow", "关闭"))
        self.actClose.setToolTip(_translate("MainWindow", "关闭本窗口"))
        self.actEdit_Undo.setText(_translate("MainWindow", "撤销"))
        self.actEdit_Undo.setToolTip(_translate("MainWindow", "撤销上次编辑操作"))
        self.actEdit_Undo.setShortcut(_translate("MainWindow", "Ctrl+Z"))
        self.acEdit_Redo.setText(_translate("MainWindow", "重做"))
        self.acEdit_Redo.setToolTip(_translate("MainWindow", "重做上次操作"))
        self.acEdit_Redo.setShortcut(_translate("MainWindow", "Ctrl+Y"))
        self.actEdit_Clear.setText(_translate("MainWindow", "清空"))
        self.actEdit_Clear.setToolTip(_translate("MainWindow", "清空"))
        self.actEdit_SelectAll.setText(_translate("MainWindow", "全选"))
        self.actEdit_SelectAll.setToolTip(_translate("MainWindow", "全选"))
        self.actEdit_SelectAll.setShortcut(_translate("MainWindow", "Ctrl+A"))
        self.actLang_CN.setText(_translate("MainWindow", "汉语"))
        self.actLang_CN.setToolTip(_translate("MainWindow", "汉语界面"))
        self.actLang_EN.setText(_translate("MainWindow", "英语"))
        self.actLang_EN.setToolTip(_translate("MainWindow", "英语"))

myMainWindow.py

#!/usr/bin/env python
# _*_ coding: UTF-8 _*_
"""=================================================
@Project -> File    : Operate-system -> myMainWindow.py
@IDE     : PyCharm
@Author  : zihan
@Date    : 2020/4/11 14:44
@Desc    :
================================================="""

import sys
from PyQt5.QtWidgets import (QApplication, QMainWindow, QActionGroup, QLabel, QProgressBar, QSpinBox, QFontComboBox)
from PyQt5.QtCore import Qt, pyqtSlot
from PyQt5.QtGui import QTextCharFormat, QFont

from ui_mainWindow import Ui_MainWindow

class QmyMainWindow(QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)

        self.__buildUI()

        # 设置斜体
        self.ui.actFont_Italic.triggered.connect(self.do_act_font_italic_triggered)
        # 设置粗体
        self.ui.actFont_Bold.triggered.connect(self.do_act_font_bold_triggered)
        # 设置下划线
        self.ui.actFont_Underline.triggered.connect(self.do_act_underline_triggered)

        # 新建文件
        self.ui.actFile_New.triggered.connect(self.do_act_file_new_triggered)
        # 打开文件
        self.ui.actFile_Open.triggered.connect(self.do_act_file_open_triggered)
        # 保存文件
        self.ui.actFile_Save.triggered.connect(self.do_act_file_save_triggered)

        # 设置字体大小
        self.__spinFontSize.valueChanged[int].connect(self.do_fontsize_changed)
        # 字体选择
        self.__comboFontName.currentIndexChanged[str].connect(self.do_fontname_changed)

        # 文本框内容可复制
        self.ui.plainTextEdit.copyAvailable.connect(self.do_plain_textedit_copyavailable)
        # 文本选择内容发生改变
        self.ui.plainTextEdit.selectionChanged.connect(self.do_plain_textedit_selectionchanged)
        # 标准右键菜单
        self.ui.plainTextEdit.customContextMenuRequested.connect(self.do_plain_textedit_customctmnreq)

        self.setCentralWidget(self.ui.plainTextEdit)

    def __buildUI(self):  # 窗体上动态添加组件
        # 创建状态栏上的组件
        self.__LabFile = QLabel(self)  # QLabel组件显示信息
        self.__LabFile.setMinimumWidth(150)
        self.__LabFile.setText("文件名：")
        self.ui.statusBar.addWidget(self.__LabFile)  # 添加到状态栏

        self.__progressBar1 = QProgressBar(self)
        self.__progressBar1.setMaximumWidth(200)
        self.__progressBar1.setMinimum(5)
        self.__progressBar1.setMaximum(50)
        sz = self.ui.plainTextEdit.font().pointSize()  # 字体大小
        self.__progressBar1.setValue(sz)
        self.ui.statusBar.addWidget(self.__progressBar1)  # 添加到状态栏

        self.__LabInfo = QLabel(self)  # QLabel组件显示字体名称
        self.__LabInfo.setText("选择字体名称：")
        self.ui.statusBar.addPermanentWidget(self.__LabInfo)  # 添加到状态栏

        # 为actLang_CN和actLang_EN创建QActionGroup，互斥型选择
        actionGroup = QActionGroup(self)
        actionGroup.addAction(self.ui.actLang_CN)
        actionGroup.addAction(self.ui.actLang_EN)
        actionGroup.setExclusive(True)  # 互斥型分组
        self.ui.actLang_CN.setChecked(True)

        # 创建工具我是谁，我在哪儿栏上的组件
        self.__spinFontSize = QSpinBox(self)  # 字体大小spinBox
        self.__spinFontSize.setMinimum(5)
        self.__spinFontSize.setMaximum(50)
        sz = self.ui.plainTextEdit.font().pointSize()
        self.__spinFontSize.setValue(sz)
        self.__spinFontSize.setMinimumWidth(50)
        self.ui.toolBar.addWidget(self.__spinFontSize)  # 添加到工具栏

        self.__comboFontName = QFontComboBox(self)  # 字体comboBox
        self.__comboFontName.setMinimumWidth(100)
        self.ui.toolBar.addWidget(self.__comboFontName)  # 添加到工具栏

        self.ui.toolBar.addSeparator()  # 添加一个分隔条
        self.ui.toolBar.addAction(self.ui.actClose)  # 添加一个关闭按钮

    @pyqtSlot(bool)
    def do_act_font_italic_triggered(self, checked):  # 斜体
        fmt = self.ui.plainTextEdit.currentCharFormat()
        fmt.setFontItalic(checked)
        self.ui.plainTextEdit.mergeCurrentCharFormat(fmt)

    @pyqtSlot(bool)
    def do_act_font_bold_triggered(self, checked):  # 粗体
        fmt = self.ui.plainTextEdit.currentCharFormat()
        if checked:
            fmt.setFontWeight(QFont.Bold)
        else:
            fmt.setFontWeight(QFont.Normal)
        self.ui.plainTextEdit.mergeCurrentCharFormat(fmt)

    @pyqtSlot(bool)
    def do_act_underline_triggered(self, checked):  # 下划线
        fmt = self.ui.plainTextEdit.currentCharFormat()
        fmt.setFontUnderline(checked)
        self.ui.plainTextEdit.mergeCurrentCharFormat(fmt)

    def do_act_file_new_triggered(self):  # 新建文件，不实现具体功能
        self.__LabFile.setText(" 新建文件")

    def do_act_file_open_triggered(self):  # 打开文件，不实现具体功能
        self.__LabFile.setText(" 打开的文件")

    def do_act_file_save_triggered(self):  # 保存文件，不实现具体功能
        self.__LabFile.setText(" 文件已保存")

    @pyqtSlot(int)
    def do_fontsize_changed(self, fontSize):  # 设置字体大小
        fmt = self.ui.plainTextEdit.currentCharFormat()
        fmt.setFontPointSize(fontSize)
        self.ui.plainTextEdit.mergeCurrentCharFormat(fmt)
        self.__progressBar1.setValue(fontSize)

    @pyqtSlot(str)
    def do_fontname_changed(self, fontName):  # 设置字体
        fmt = self.ui.plainTextEdit.currentCharFormat()
        fmt.setFontFamily(fontName)
        self.ui.plainTextEdit.mergeCurrentCharFormat(fmt)
        self.__LabInfo.setText("字体名称：%s    " % fontName)

    # 文本内容可复制
    def do_plain_textedit_copyavailable(self, avi):
        self.ui.actEdit_Cut.setEnabled(avi)
        self.ui.actEdit_Copy.setEnabled(avi)
        self.ui.actEdit_Paste.setEnabled(self.ui.plainTextEdit.canPaste())

    # 文本选择内容发生改变时
    def do_plain_textedit_selectionchanged(self):
        fmt = self.ui.plainTextEdit.currentCharFormat()
        self.ui.actFont_Bold.setChecked(fmt.font().bold())
        self.ui.actFont_Italic.setChecked(fmt.fontItalic())
        self.ui.actFont_Underline.setChecked(fmt.fontUnderline())

    # 标准右键菜单
    def do_plain_textedit_customctmnreq(self, pos):
        popMenu = self.ui.plainTextEdit.createStandardContextMenu()
        popMenu.exec(pos)  # 显示快捷菜单

if __name__ == "__main__":
    app = QApplication(sys.argv)  # 创建app，用QApplication类
    form = QmyMainWindow()
    form.show()
    sys.exit(app.exec_())

特别提醒一点的是可以自己在Property里面设置剪切-复制-粘贴等的初始状态disable，只需要去掉Enable那个属性的勾就好了。至于怎么使它Enable，对于PlainTextEdit控件来说，有一个槽函数copyAvailable可以设置他们的使能。另外那个customContextMenuRequested(pos)函数在这个程序里面还没发现什么作用，没有什么特别的功能，如果有人发现了，可以告诉我一下，哈哈哈。