PyQt5_例1（图标、状态栏、菜单栏、工具栏）

#!/usr/bin/env python

from PyQt5.QtCore import (QFile, QFileInfo, QPoint, QRect, QSettings, QSize,
Qt, QTextStream)
from PyQt5.QtGui import QIcon, QKeySequence
from PyQt5.QtWidgets import (QAction, QApplication, QFileDialog, QMainWindow,
QMessageBox, QTextEdit)

class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()

self.curFile = ''
#创建TestEdit，并居中
self.textEdit = QTextEdit()
self.setCentralWidget(self.textEdit)

self.createActions()
self.createMenus()
self.createToolBars()
self.createStatusBar()

self.readSettings()

self.textEdit.document().contentsChanged.connect(self.documentWasModified)

self.setCurrentFile('')

def closeEvent(self, event):
if self.maybeSave():
self.writeSettings()
event.accept()
else:
event.ignore()

def newFile(self):
if self.maybeSave():
self.textEdit.clear()
self.setCurrentFile('')

def open(self):
#检查当前是否做了修改
if self.maybeSave():
fileName, _ = QFileDialog.getOpenFileName(self)
if fileName:
self.loadFile(fileName)
#保存文件
def save(self):
#如果修改的文件已经存在
if self.curFile:
return self.saveFile(self.curFile)
#否则另存为
return self.saveAs()

def saveAs(self):
fileName, _ = QFileDialog.getSaveFileName(self)
if fileName:
return self.saveFile(fileName)

return False

def about(self):
QMessageBox.about(self, "About Application",
"The <b>Application</b> example demonstrates how to write "
"modern GUI applications using Qt, with a menu bar, "
"toolbars, and a status bar.")

def documentWasModified(self):
self.setWindowModified(self.textEdit.document().isModified())
#QAction
def createActions(self):
root = QFileInfo(__file__).absolutePath()

self.newAct = QAction(QIcon(root + '/images/new.png'), "&New", self,
shortcut=QKeySequence.New, statusTip="Create a new file",
triggered=self.newFile)

self.openAct = QAction(QIcon(root + '/images/open.png'), "&Open...",
self, shortcut=QKeySequence.Open,
statusTip="Open an existing file", triggered=self.open)

self.saveAct = QAction(QIcon(root + '/images/save.png'), "&Save", self,
shortcut=QKeySequence.Save,
statusTip="Save the document to disk", triggered=self.save)

self.saveAsAct = QAction("Save &As...", self,
shortcut=QKeySequence.SaveAs,
statusTip="Save the document under a new name",
triggered=self.saveAs)

self.exitAct = QAction("E&xit", self, shortcut="Ctrl+Q",
statusTip="Exit the application", triggered=self.close)

self.cutAct = QAction(QIcon(root + '/images/cut.png'), "&Cut", self,
shortcut=QKeySequence.Cut,
statusTip="Cut the current selection's contents to the clipboard",
triggered=self.textEdit.cut)

self.copyAct = QAction(QIcon(root + '/images/copy.png'), "&Copy", self,
shortcut=QKeySequence.Copy,
statusTip="Copy the current selection's contents to the clipboard",
triggered=self.textEdit.copy)

self.pasteAct = QAction(QIcon(root + '/images/paste.png'), "&Paste",
self, shortcut=QKeySequence.Paste,
statusTip="Paste the clipboard's contents into the current selection",
triggered=self.textEdit.paste)

self.aboutAct = QAction("&About", self,
statusTip="Show the application's About box",
triggered=self.about)

self.aboutQtAct = QAction("About &Qt", self,
statusTip="Show the Qt library's About box",
triggered=QApplication.instance().aboutQt)
#初始状态时将cutAct和copyAct禁止
self.cutAct.setEnabled(False)
self.copyAct.setEnabled(False)
#当文本框里有内容的时候将cutAct和copyAct打开
self.textEdit.copyAvailable.connect(self.cutAct.setEnabled)
self.textEdit.copyAvailable.connect(self.copyAct.setEnabled)
#菜单
def createMenus(self):
self.fileMenu = self.menuBar().addMenu("&File")
self.fileMenu.addAction(self.newAct)
self.fileMenu.addAction(self.openAct)
self.fileMenu.addAction(self.saveAct)
self.fileMenu.addAction(self.saveAsAct)
self.fileMenu.addSeparator();
self.fileMenu.addAction(self.exitAct)

self.editMenu = self.menuBar().addMenu("&Edit")
self.editMenu.addAction(self.cutAct)
self.editMenu.addAction(self.copyAct)
self.editMenu.addAction(self.pasteAct)

self.menuBar().addSeparator()

self.helpMenu = self.menuBar().addMenu("&Help")
self.helpMenu.addAction(self.aboutAct)
self.helpMenu.addAction(self.aboutQtAct)
#工具栏
def createToolBars(self):
self.fileToolBar = self.addToolBar("File")
self.fileToolBar.addAction(self.newAct)
self.fileToolBar.addAction(self.openAct)
self.fileToolBar.addAction(self.saveAct)

self.editToolBar = self.addToolBar("Edit")
self.editToolBar.addAction(self.cutAct)
self.editToolBar.addAction(self.copyAct)
self.editToolBar.addAction(self.pasteAct)
#状态栏显示”ready“
def createStatusBar(self):
self.statusBar().showMessage("Ready")

def readSettings(self):
#创建一个QSettings，第一个参数是公司名，后一个参数可以是项目名
#settings = QSettings("Trolltech", "Application Example")
settings = QSettings("./Qt.ini", QSettings.IniFormat)
#设定窗口位置、大小默认值
pos = settings.value("pos", QPoint(200, 200))
size = settings.value("size", QSize(400, 400))
self.resize(size)
self.move(pos)
"""
QSettings具体参数可以用python查看
from PyQt5.QtCore import QSettings
help(QSettings)
"""
def writeSettings(self):
settings = QSettings("./Qt.ini", QSettings.IniFormat)
settings.setValue("pos", self.pos())
settings.setValue("size", self.size())

def maybeSave(self):
#检查是否做了修改
if self.textEdit.document().isModified():
#进行提示，提供三个选择
ret = QMessageBox.warning(self, "Application",
"The document has been modified.\nDo you want to save "
"your changes?",
QMessageBox.Save | QMessageBox.Discard | QMessageBox.Cancel)

if ret == QMessageBox.Save:
return self.save()

if ret == QMessageBox.Cancel:
return False

return True

def loadFile(self, fileName):
file = QFile(fileName)
if not file.open(QFile.ReadOnly | QFile.Text):
QMessageBox.warning(self, "Application",
"Cannot read file %s:\n%s." % (fileName, file.errorString()))
return

inf = QTextStream(file)
QApplication.setOverrideCursor(Qt.WaitCursor)
self.textEdit.setPlainText(inf.readAll())
QApplication.restoreOverrideCursor()

self.setCurrentFile(fileName)
self.statusBar().showMessage("File loaded", 2000)
#文件进行保存
def saveFile(self, fileName):
#QFile实例化
file = QFile(fileName)
'''参数有：ReadOnly/WriteOnly/ReadWrite/Append/Truncate/
Text/Unbuffered'''
if not file.open(QFile.WriteOnly | QFile.Text):
QMessageBox.warning(self, "Application",
"Cannot write file %s:\n%s." % (fileName, file.errorString()))
return False
#相当于一个数据流buffer
outf = QTextStream(file)
#设置为等待光标
QApplication.setOverrideCursor(Qt.WaitCursor)
#读取textEdit内容，往数据流中写入.
outf << self.textEdit.toPlainText()
file.close()
#恢复为普通光标
QApplication.restoreOverrideCursor()

self.setCurrentFile(fileName);

#5000：显示的时长
self.statusBar().showMessage("File saved", 5000)
return True

def setCurrentFile(self, fileName):
self.curFile = fileName
self.textEdit.document().setModified(False)
self.setWindowModified(False)

if self.curFile:
#移除文件名中的路径字符
shownName = self.strippedName(self.curFile)
else:
shownName = 'untitled.txt'
#设置窗口标题
self.setWindowTitle("%s[*] - Application" % shownName)

def strippedName(self, fullFileName):
#返回文件名
return QFileInfo(fullFileName).fileName()

if __name__ == '__main__':

import sys

app = QApplication(sys.argv)
mainWin = MainWindow()
mainWin.show()
sys.exit(app.exec_())